47th Annual DPS MeetingNational Harbor MD ndash November 2015

Meeting Abstracts

Session Table of Contents100 ndash New Horizons Plenary Session101 ndash Pluto System I--New HorizonsHeadliner102 ndash Pluto System II--Pluto Surface andSatellites103 ndash Ceres Jubilee and Vested Interests104 ndash Planetary Rings105 ndash Pluto System III--PlutosAtmosphere106 ndash The Asteroid Composition ChannelFrom Soft Rock to Heavy Metal107 ndash Mercury and the Moon200 ndash Pluto System IV--Saving the Best forLast201 ndash sup3Venus Asteroid Dynamics202 ndash EPO - Scientists Showcase203 ndash Centaurs Trans-Neptunian Objectsand the Inner Oort Cloud204 ndash Asteroid Radar amp Thermal StudiesMicrowaved and Served Hot205 ndash Titans Atmosphere207 ndash Harold C Urey Prize No Photon LeftBehind How Modern Spectroscopy isTransforming Planetary SciencesGeronimo Villanueva (NASA GoddardSpace Flight Center)208 ndash Changing Perspectives on Mercuryand the Moon Brett Denevi (JohnsHopkins APL)209 ndash Vesta and Ceres by the Light ofDawn Christopher Russell (UC LosAngeles)210 ndash Pluto System211 ndash Centaurs Trans-Neptunian Objectsand the Inner Oort Cloud212 ndash Spiraling in on Ceres and VestaRedux213 ndash Asteroid Surfaces214 ndash Asteroid Dynamics215 ndash Mercury and the Moon

216 ndash Beyond the Moon The LunarCommunity Branches Out217 ndash Venus218 ndash Planetary Rings219 ndash EPO - Scientists ShowcasePrograms and Best Practices300 ndash Titans Atmosphere and Surface301 ndash Asteroid Surveys See and Say302 ndash Formation of Planets Satellites andSmall Bodies304 ndash Gerard P Kuiper Prize Chemistry ofPlanetary Atmospheres Insights andProspects Yuk Yung (Caltech)305 ndash MAVEN Mission to Mars Results onUpper Atmosphere IonosphereSolar-Wind Interactions and Escape toSpace Bruce Jakosky (University ofColorado)306 ndash New Views on Inner Solar Systemsand Extreme Planets Rebekah Dawson(University of California Berkeley)307 ndash Asteroid Spin States308 ndash Asteroid Observational Surveys309 ndash Formation of Planets Satellites andSmall Bodies310 ndash Titans Surface and Atmosphere311 ndash Jovian Planets Atmospheres andInteriors312 ndash Future Missions Instruments andFacilities400 ndash Jovian Planet Atmospheres Stormsand Upper Atmosphere401 ndash Marss Atmosphere and Surface402 ndash Asteroid Spins YORP and InteriorsThe Turning and Turning The CentreCannot Hold403 ndash Jovian Planet Interiors DeepAtmosphere and Structure404 ndash Extrasolar Planets Terrestrial andNeptunian Planets

405 ndash Galilean Satellites406 ndash Harold Masursky Award The CSWASurvey on Workplace Climate andAnti-Harassment Policies Christina Richey(NASA HQ)407 ndash Rosetta at Perihelion The JourneyContinues Paul Weissman (PlanetaryScience Institute)408 ndash 20 Years of Exoplanets FromSurveys Towards Characterization EmilyRauscher (University of Michigan)409 ndash Galilean Satellites410 ndash Enceladus411 ndash Icy Satellites412 ndash Irregular Satellites413 ndash 67PChuryumov-Gerasimenko414 ndash Active Asteroids415 ndash Comets Physical CharacteristicsDynamics and Composition416 ndash Characterization of Extrasolar Planets417 ndash Discoveries and Dynamics ofExtrasolar Planets418 ndash Origins of Planetary Systems419 ndash Marss Atmosphere420 ndash Mars Surface and Interior500 ndash Comet 67PC-G -- Nucleus501 ndash Extrasolar Planets Discovery andDynamics502 ndash Jovian Planet MagnetospheresAurorae and Atmospheres503 ndash Comet 67PC-G -- Coma andEnvironment504 ndash Extrasolar Planets Giant PlanetAtmospheres505 ndash Marss Atmosphere506 ndash Comets Physical CharacteristicsDynamics and Composition507 ndash Origins of Planetary Systems508 ndash Icy Satellites

1

100 ndash New Horizons Plenary Session10001 ndash The Pluto System Initial Results from theExploration by New HorizonsThe Pluto system was recently explored by NASArsquos New Horizonsspacecraft which made closest approach on 14 July 2015 Plutorsquossurface is found to be remarkably diverse in landforms terrainages and albedo color and composition gradients Strongevidence is found for a water-ice crust geologically young surfaceunits ice convection wind streaks and glacial flow Plutorsquosatmosphere is found to be very extended and contains newlydiscovered trace hydrocarbons has an extensive global haze layerand a surprisingly low surface pressure of ~10 microbars Plutorsquoswide range of surface expressions and long term activity raisesfundamental questions about how small planets can have activeprocesses billions of years after their formation The geology ofPlutorsquos large moon Charonrsquos is also surprisingly diverse displayingtectonics and evidence for a heterogeneous crustal compositionthe north pole displays puzzling dark terrain No evidence for aCharon atmosphere is found Plutorsquos small satellites Hydra and Nixare small elongated objects with higher albedos than expectedSurprisingly despite much improved diameter limits no newsatellites are found We will present an overview of the NewHorizons flyby payload and results This work was supported bythe NASA New Horizons project

Author(s) SA Stern Harold Weaver Leslie Young Catherine Olkin Kimberly Ennico Jeff Moore Will Grundy Randall Gladstone Fran BagenalInstitution(s) 1 Johns Hopkins Applied Physics Laboratory 2Lowell Observatory 3 NASA Ames Research Center 4 SwRI 5SwRI 6 University of Colorado

10002 ndash New Horizons Investigations of Charon andPlutos Small MoonsDuring the flyby of the Pluto system in July 2014 the instrumentson the New Horizons spacecraft (Weaver et al 2008 Space SciRev 140 75) acquired spatially resolved measurements of Charonand Plutos small moons (Styx Nix Kerberos and Hydra) Thesunlit hemisphere of Charon was mapped in panchromatic lightwith resolutions as high as 015 kmpix using LORRI and in fourdifferent color bands (400ndash550 nm 540-700 nm 780ndash975 nm860-910 nm the latter is centered on a weak CH4 band) withresolutions as high as 14 kmpix using MVIC Composition mapsof Charon were obtained with the LEISA infrared spectral imager inthe wavelength range 125-250 microns with a spectral resolvingpower of ~250 and with spatial resolutions up to 49 kmpix Solaroccultation observations with the Alice ultraviolet spectrographand radio occultation measurements with REX were used tosearch for an atmosphere around Charon Nix was observed byLORRI in panchromatic light at 030 kmpix by MVIC in color at20 kmpix and by LEISA at 36 kmpix (the latter to bedownlinked later) Hydra was observed by LORRI in panchromaticlight at 11 kmpix in color at 46 kmpix and by LEISA at 149kmpix (the latter to be downlinked later) Limited resolvedmeasurements of Kerberos (20 kmpix panchromatic 80 kmpixcolor) and Styx (32 kmpix panchromatic 80 kmpix color) werealso obtained but have not yet been downlinked An extensiveseries of unresolved photometric measurements of Plutos smallmoons were obtained with LORRI during several monthspreceeding closest approach in mid-July which place tightconstraints on their shapes and rotational statesThe New Horizons data have revealed that Charon has surprisinglydiverse terrain with evidence of tectonics and a heterogeneouscrustal composition Nix and Hydra are highly elongated bodieswith high average albedos (suggesting water-ice dominatedsurfaces) and significant albedo and color variations over theirsurfaces We will present estimates for the densities spin periodsand physical properties of all the small satellites This work wassupported by NASAs New Horizons project

Author(s) Harold A Weaver S A Stern L A Young CB Olkin K Ennico J M Moore W B McKinnon J RSpencer W M Grundy D P Cruikshank G P Gladstone ME Summers F BagenalInstitution(s) 1 George Mason University 2 Johns HopkinsAPL 3 Lowell Observatory 4 NASA Ames Research Center 5Southwest Research Institute 6 University of Colorado 7Washington University

10003 ndash Geology of Pluto and Charon OverviewPlutorsquos surface was found to be remarkably diverse in terms of itsrange of landforms terrain ages and inferred geological processesThere is a latitudinal zonation of albedo The conspicuous brightalbedo heart-shaped feature informally named Tombaugh Regio iscomprised of several terrain types Most striking is Texas-sizedSputnik Planum which is apparently level has no observablecraters and is divided by polygons and ovoids bounded by shallowtroughs Small smooth hills are seen in some of the polygon-bounding troughs These hills could either be extruded or exposedby erosion Sputnik Planum polygonovoid formation hypothesesrange from convection to contraction but convection is currentlyfavored There is evidence of flow of plains material aroundobstacles Mountains especially those seen south of SputnikPlanum exhibit too much relief to be made of CH CO or N andthus are probably composed of H O-ice basement material Thenorth contact of Sputnik Planum abuts a scarp above which isheavily modified cratered terrain Plutorsquos large moon Charon isgenerally heavily to moderately cratered There is a mysteriousstructure in the arctic Charonrsquos surface is crossed by an extensivesystem of rift faults and graben Some regions are smoother andless cratered reminiscent of lunar maria On such a plain are largeisolated block mountains surrounded by moats At this conferencewe will present highlights of the latest observations and analysisThis work was supported by NASAs New Horizons project

Author(s) Jeffrey M Moore S A Stern H A Weaver Leslie A Young Kimberly Ennico Cathy B OlkinInstitution(s) 1 Johns Hopkins University Applied PhysicsLaboratory 2 NASA Ames Research Center 3 SouthwestResearch Institute

10004 ndash Pluto System Surface Composition ResultsThis talk will present an overview of surface compositiondiscoveries from New Horizons exploration of the Pluto systemThe emphasis will be on results that could only have been obtainedthanks to the uniquely high spatial resolution provided by aspacecraft visit The Ralph instrument is New Horizons primarytool for investigating surface compositions in the Pluto systemRalph consists of a near-infrared spectral imager sharing a 75 mmaperture telescope assembly with a color CCD camera system TheLinear Etalon Imaging Spectral Array (LEISA) component of Ralphprovides spectral coverage from 125 ndash 25 microm at a resolving power(λΔλ) of 240 Ices such as CH N CO CO C H NH andH O have uniquely diagnostic absorption bands in this wavelengthregion The Multi-spectral Visible Imaging Camera (MVIC) has 7CCD arrays of which 4 have interference filters affixed directly onthe focal plane The filters pass wavelengths ranging from 400through 975 nm sensitive to coloration by tholin-type materials aswell as a weak CH4 ice absorption band at 890 nm Both Ralphcomponents are usually operated in a scanning mode rotating thespacecraft about its Z axis to sweep Ralphs field of view across thescene such that each point in the scene is eventually imaged at eachwavelength The width of the scanned region is 09 degrees dividedinto 256 spatial pixels for LEISA and 57 degrees spanned by 5000pixels for MVIC Over the course of the summer 2015 flybynumerous Ralph observations targeted the various bodies in thePluto system As of late 2015 transmission of the data to Earthcontinues but already a number of spectacular data sets areavailable for analysis including LEISA scans of Pluto at 6 to 7kmpixel and of Charon at 3 kmpixel as well as MVIC scans ofPluto at 700 mpixel and of Charon at 5 kmpixel This work wassupported by the NASA New Horizons Project

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Author(s) William M Grundy R P Binzel J C Cook D PCruikshank C M Dalle Ore A M Earle K Ennico D EJennings C JA Howett I R Linscott A W Lunsford C BOlkin A H Parker J Wm Parker S Protopapa D C Reuter KN Singer J R Spencer S A Stern C CC Tsang A J Verbiscer H A Weaver L A YoungInstitution(s) 1 Johns Hopkins University Applied PhysicsLaboratory 2 Lowell Obs 3 MIT 4 NASA Ames ResearchCenter 5 NASA Goddard Space Flight Center 6 StanfordUniversity 7 SwRI 8 University of Maryland 9 University ofVirginia

10005 ndash New Horizons Observations of theAtmospheres of Pluto and CharonMajor goals of the New Horizons (NH) mission are to explore andcharacterize the structure and composition of Plutorsquos atmosphereand to establish whether Charon has a measurable atmosphere ofits own The primary instruments onboard NH which contribute tothese goals are the REX instrument through uplink X-band radiooccultations the Alice instrument through extreme- andfar-ultraviolet solar occultations and the LORRI panchromaticimager through high-phase-angle imaging The associateddatasets were obtained following closest approach of NH to PlutoPressure and temperature profiles of the lower atmosphere arederived from the REX data the composition and structure of theextended atmosphere are derived from the Alice data (supported byapproach observations of reflected ultraviolet sunlight) and thedistribution and properties of Plutorsquos hazes are derived from theLORRI data In this talk an overview of the early atmospherescience results will be presentedThis work was supported by NASAs New Horizons project

Author(s) G R Gladstone S A Stern H A Weaver L AYoung K A Ennico C B Olkin A F Cheng T KGreathouse D P Hinson J A Kammer I R Linscott A HParker J Wm Parker K D Retherford E Schindhelm K NSinger A J Steffl D F Strobel M E Summers C C CTsang G L Tyler M H Versteeg W W Woods NCunningham W CurdtInstitution(s) 1 George Mason University 2 Max PlanckInstitute for Solar System Research 3 NASA Ames ResearchCenter 4 Nebraska Wesleyan University 5 SETI Institute 6Southwest Research Inst 7 The Johns Hopkins University 8 TheJohns Hopkins University Applied Physics Laboratory

10006 ndash Solar wind interaction with Plutorsquos escapingatmosphereNASArsquos New Horizons spacecraft carries two instruments SWAPand PEPSSI that measure low and high energy particlesrespectively These particle instruments have been measuring theconditions in the solar wind for most of the trajectory from Earth toPluto The Venetia Burney Student Dust Counter measuredimpacts from micron-sixed dust particles These particleinstruments also made observations during the flyby of Pluto onJuly 14 2015 We report on New Horizons measurements of theinteraction of the solar wind interaction with Plutorsquos extendedatmosphere and discuss comparisons with theoretical expectations

Author(s) Fran Bagenal S A Stern H A Weaver L AYoung K Ennico C Olkin D J McComas R L McNutt MHoranyi H A Elliott M E Hill E Zernstein P Kollman S MKrimigis C M Lisse D F Strobel J SzalAy M PiquetteInstitution(s) 1 JHU-APL 2 NASA Ames Research Center 3Southwest Research Institute 4 Southwest Research Institute 5The Johns Hopkins University 6 Univ of Colorado

101 ndash Pluto System I--New HorizonsHeadliner10101 ndash Color Variations on Pluto Charon amp AmongPlutorsquos Small SatellitesThis summerrsquos flyby of NASArsquos New Horizons spacecraft past Pluto

provided the first high spatial resolution imaging of the systemUsing the Ralph instrument (Reuter et al 2008 Space Sci Rev140 129) color images were obtained in 3 broadband filters andone narrow band filter blue (400 ndash 550 nm) red (540-700 nm)NIR (780 ndash 975 nm) and methane (860 ndash 910 nm) These datarevealed details about Plutorsquos variegated surface including distinctcolor boundaries in two halves of the region informally namedTombaugh Regio and intriguing color variations in Plutorsquos northpole This talk will discuss the color variations on Pluto CharonNix and Hydra Color observations of Kerberos and Styx weretaken but will not be downlinked in time for inclusion in this talkThis work was supported by NASArsquos New Horizons project

Author(s) Catherine B Olkin D C Reuter S A Stern CJ A Howett A H Parker K Ennico K N Singer W MGrundy H A Weaver L A Young R P Binzel M W Buie J C Cook D P Cruikshank C M Dalle Ore A M Earle DE Jennings I R Linscott A W Lunsford J Wm Parker SProtopapa J R Spencer CCC Tsang A J VerbiscerInstitution(s) 1 Johns Hopkins University Applied PhysicsLaboratory 2 Lowell Observatory 3 MIT 4 NASA AmesResearch Center 5 NASA Goddard Space Flight Center 6Stanford University 7 SWRI 8 University of Maryland 9University of Virginia

10102 ndash Pluto Distribution of ices and coloringagents from New Horizons LEISA observationsPluto was observed at high spatial resolution (maximum ~3kmpx) by the New Horizons LEISA imaging spectrometer LEISAis a component of the Ralph instrument (Reuter DC Stern SAScherrer J et al 2008 Space Sci Rev 140 129) and affords aspectral resolving power of 240 in the wavelength range 125-25microm and 560 in the range 21-225 microm Spatially resolved spectrawith LEISA are used to map the distributions of the known ices onPluto (N CH CO) and to search for other surface componentsThe spatial distribution of volatile ices is compared with thedistribution of the coloring agent(s) on Plutos surface Thecorrelation of ice abundance and the degree of color (ranging fromyellow to orange to dark red) is consistent with the presence oftholins which are refractory organic solids of complex structureand high molecular weight with colors consistent with thoseobserved on Pluto Tholins are readily synthesized in the laboratoryby energetic processing of mixtures of the ices (N CH CO)known on Plutos surface We present results returned from thespacecraft to date obtained from the analysis of the high spatialresolution dataset obtained near the time of closest approach to theplanet Supported by NASArsquos New Horizons project

Author(s) Dale P Cruikshank William M Grundy S AlanStern Catherine B Olkin Jason C Cook Cristina M DalleOre Richard P Binzel Alissa M Earle Kimberly Ennico Donald E Jennings Carly JA Howett Ivan R Linscott AllenW Lunsford Alex H Parker Joel W Parker SilviaProtopapa Dennis C Reuter Kelsi N Singer John RSpencer Constantine C C Tsang Anne J Verbiscer HaroldA Weaver Leslie A YoungInstitution(s) 1 Applied Phys Lab 2 Lowell Observatory 3MIT 4 NASA Ames Research Center 5 NASA Goddard SpaceFlight Center 6 SETI Institute 7 Stanford Univ 8 SWRI 9Univ Maryland 10 Univ Virginia

10103 ndash First Results from The New Horizons RadioScience Experiment Measurements of PlutosAtmospheric Structure Surface Pressure andMicrowave Brightness TemperatureThe Radio Science Experiment (REX) on board the New Horizonsspacecraft measured key characteristics of Pluto and Charonduring the July 14 2015 flyby The REX flight instrument isintegrated into the NH X-band radio transceiver and provides highprecision narrow band recording of powerful uplink transmissionsfrom Earth stations as well as a record of broadband radiometricpower This presentation reviews the performance and initialresults of the radio occultation of Pluto the radiometrictemperature profiles and gravity measurements during the

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encounter REX received two pair of 20-kW uplink signals onepair per polarization transmitted from the DSN at 42- cmwavelength during a diametric radio occultation of Pluto The REXrecording of the uplinks affords a precise measurement of thesurface pressure the temperature structure of the loweratmosphere and the surface radius of Pluto The ingress portion ofone polarization was played back from the spacecraft in July whilethe egress portion of the same polarization was played back inAugust Both ingress and egress segments of the occultation havebeen processed to obtain the pressure and temperature structure ofPlutorsquos atmosphere In addition REX measured the thermalemission from Pluto at 42- cm wavelength during two linear scansacross the disk at close range when both the dayside and the nightside were visible Both scans extend from limb to limb with aresolution of one-tenth Plutorsquos disk and temperature resolution of01 K A third radiometric scan was obtained during the dark sidetransit of the occultation This work was supported by NASArsquos NewHorizons project

Author(s) Ivan Linscott Alan Stern Hal Weaver LeslieYoung Cathy Olkin Kim EnnicoInstitution(s) 1 JHUAPL 2 NASA AMES 3 StanfordUniversity 4 SWRI

10104 ndash Volatile Transport Implications from the NewHorizons Flyby of PlutoThe New Horizons flyby of Pluto has revealed a striking range ofterrains from the very bright region informally named SputnikPlanum to very dark regions such as the informally namedCthulhu Regio Such a variety was beyond the scope of recentmodels of Plutos seasonal volatile cycle (Young 2013 ApJL 766L22 Hansen Paige and Young 2015 Icarus 246 183) whichassumed globally uniform substrate albedos The Exchange withPressure Plateau (EPP) class of models in Young (2013) and thefavored runs from Hansen et al (2015) had long periods ofexchange of volatiles between northern and southern hemispheresIn these models the equators were largely devoid of volatiles eventhough the equatorial latitudes received less insolation than thepoles over a Pluto year they were never the coldest place on the icyworld New models that include a variety of substrate albedos caninvestigate questions such as whether Sputnik Planum has analbedo that is high enough to act as a local cold trap for much ofPlutos year We will present the implications of this and otherassumption-busting revelations from the New Horizons flyby Thiswork was supported by NASArsquos New Horizons project

Author(s) Leslie Young William M Grundy RIchard PBinzel Alissa M Earle Ivan R Linscott David P Hinson Amanda M Zangari William B McKinnon S Alan Stern Harold A Weaver Catherine B Olkin Kimberly Ennico GRandall Gladstone Michael E Summers Jeffrey M Moore John R SpencerInstitution(s) 1 George Mason University 2 Johns HopkinsUniversity Applied Physics Laboratory 3 Lowell Observatory 4MIT 5 NASA Ames Research Center 6 Southwest Research Inst7 Stanford University 8 Washington Univ in St Louis

10105 ndash Small Satellites and Dust in the Pluto SystemUpper Limits and ImplicationsTo help ensure safe passage of the New Horizons (NH) spacecraftas it flew through the Pluto system we took a series of deep imageswith the Long Range Reconnaissance Imager (LORRI) to searchfor previously undetected satellites or rings We obtained a total of1100 10-second exposures spread over 20 epochs between May 11and July 1 2015 HST observations had previously set an upperlimit to the brightness of undetected moons of about half Styxsbrightness (ie a diameter of ~5 km for an a Charon-like albedo of038) The final NH observations in early July could have detectedobjects down to ~15 km in diameter in the Charon - Hydra regionand ~2 km between Charons orbit and ~5000 km above Plutossurface Despite the sensitivity of the searches no additionalmoons were found The lower limit on the brightness ratio betweenStyx and any undiscovered fainter satellites ~20 is comparable tothe brightness ratio between Nix and Kerberos (~16) and a

power-law satellite size distribution analogous to that seen in theSaturn system cannot be ruled out Implications of the satellitesize distribution for the origin of the satellite system will bediscussed The data also place an upper limit of ~1 x 10 on the IFof any dust rings in the vicinity of the known small satellites afactor of several improvement over previous HST limits This workwas supported by NASArsquos New Horizons project

Author(s) John R Spencer Mark R Showalter S AlanStern Marina Brozovic Marc W Buie Douglas P Hamilton Robert A Jacobson David E Kaufmann Tod R Lauer Alex HParker Simon B Porter Henry B Throop Anne J Verbiscer Harold A Weaver Leslie A Young Kimberly Ennico CatherineB OlkinInstitution(s) 1 Applied Physics Laboratory 2 Jet PropulsionLaboratory 3 NASA Ames Research Center 4 National OpticalAstronomy Observatory 5 Planetary Science Institute 6 SETIInstitute 7 Southwest Research Institute 8 University ofMaryland 9 University of Virginia

10106 ndash What We Know Now Synthesis forUnderstanding the Origin of the Pluto SystemThe July 2015 New Horizons flyby has removed a long-standingobstacle to understanding the cosmogony of the Pluto-Charonsystem the uncertain radius of Pluto Combined with preciseastrometric fits to the barycenter of the Pluto-Charon binary fromHST observations of the more distant small satellites (Brozovic etal Icarus 246 317ndash329 2015) the densities of both Pluto andCharon are now known At the 10 level these densities are rathersimilar as opposed to the more divergent density estimates of yearspast in which Charon was thought to be substantially icier In thecontext of a ldquogiant impactrdquo origin a rock-rich Charon implies thatthe precursor impacting bodies were at most only partiallydifferentiated mdash possessing relatively thin ice shells (CanupAstron J 141 35 2011) This suggests some combination ofrelatively slow andor late accretion in the ancestral Kuiper beltNew Horizons has also shown that Nix and Hydra possess highalbedos consistent with ice-dominated compositions Suchcompositions are consistent with a giant impact origin in which oneor both precursor impacting bodies were partially differentiated sothat the small satellites ultimately formed from material ejectedfrom ice-dominated surface layers (Peale and Canup Treatise onGeophysics 2 Ed chapter 1017 2015) We examine whetherPluto and Charon could actually possess the same bulk rockiceratio and whether this would allow for an alternate non-giant-impact origin for the Pluto systemThis work was supported by NASAs New Horizons project

Author(s) William B McKinnon S A Stern H AWeaver J R Spencer F Nimmo C M Lisse O MUmurhan J M Moore M W Buie S B Porter C B Olkin L A Young K EnnicoInstitution(s) 1 APL 2 NASA Ames 3 SETI 4 SwRI 5 UCSC6 Washington Univ

102 ndash Pluto System II--Pluto Surface andSatellites10201D ndash Vigorous Convection Underlies PlutorsquosSurface ActivityAgainst many expectations New Horizonsrsquo images of the surface ofPluto and Charon show seemingly young surfaces On Plutoimages of an equatorial region south of the Tombaugh Regio reveala mountain range with peaks jutting as high as 3500 meters Thelow concentration of craters for these mountains suggests an age of100 million years indicating that Pluto is geologically active Otherevidence for geologic activity includes a fault cross-cutting ridgessmooth lightly cratered plains with flow fronts and a pair ofapparent stratovolcanoes Charon similarly possesses very fewcraters and a spectacular system of troughs Both observationssuggest the possible presence of active cryogeysers andcryovolcanoes The underlying cause of modern tectonic andvolcanic activity on any object is likely a vigorous mantle

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convection regime We are thus led to consider what determinesplanetary vigor While Pluto and Charon seem to be quite activeCeres and the much larger Callisto seem to lack modern endogenicactivity even though all of these bodies are likely to possess waterice mantlesWe coupled a parameterized convection model with a temperaturedependent rheology for pure water ice deducing a barely criticalRayleigh number of ~1600 for Plutorsquos mantle and lt1000 forCharon suggesting that a water ice mantle alone may beinsufficient to support vigorous convection in these bodiesHowever in the outer solar system other volatiles may havecondensed Ammonium hydrate has been reported on the surfaceof Charon At temperatures above the eutectic (176 K) Durham etal (1993) showed that NH lowers the viscosity of water ice by 4orders of magnitude Our model indicates that with NH themean temperature of the mantle of Pluto is at the eutectic and itsRa ~ 10^4 The presence of NH dramatically increases the vigor ofconvection for the two bodies and suggests that ammonia-waterslurries are the basis for Plutorsquos volcanism We propose that thepresence or absence of active mantle convection may offer auniversal criterion for endogenic planetary vigor

Author(s) Alexander J Trowbridge Henry Jay Melosh Andy M FreedInstitution(s) 1 Purdue University

10202 ndash Craters on Pluto and Charon Characteristicsand Impactor PopulationAlthough both Pluto and Charon have a surprising number ofyoung-looking surfaces there are still plenty of craters for impact-phenomenon enthusiasts We will present size morphologyejecta and albedo pattern statistics in addition to correlations withcolorcomposition where possible We use images and topographyfrom the Long Range Reconnaissance Imager (LORRI Cheng etal 2008 SSR 140 189-215) and data from the Ralph (Reuter etal 2008 SSR 140 129-154) colorcomposition instrumentsImpactor sizes will be estimated from relevant scaling laws for coldwater ice (see details in Singer and Stern 2015 ApJL 808 L50)For Pluto an image strip at 125 m px includes some crateredterrains and much of the encounter hemisphere (the anti-Charonhemisphere) will be covered at ~400 m px The ~smallest cratersobservable at these pixel scales (using a 5 pixel limit) would be~063 km and ~2 km in diameter respectively with impactordiameters estimated at ~50 m and ~200 m However it is likelythat degradation processes may obscure small craters thus thislower observation limit will depend on terrain type Additionallylighting and observation geometries vary across the disk whichmay make crater detection difficult in some areas All of theilluminated portions of Pluto (during its 64 day rotation period)were imaged at ~20 km px or better during the encounter Thehighest resolution images of Pluto (at ~80 m px ) occur in anarrow strip and are not scheduled for downlink before the DPSThe highest resolution Charon coverage (a strip at ~160 m px ) abroader swath at 400 m px and the entire encounter hemisphere(the sub-Pluto hemisphere) at ~890 m px may yield craters assmall as 08 2 and 45 km in diameter respectively The inferredimpactor sizes for these craters would be ~50 m 160 m and 440 mAlthough the dataset is limited we will discuss what constraintscan be put on the impactor population This work was supported bythe NASA New Horizons project

Author(s) Kelsi N Singer Paul M Schenk Stuart JRobbins Veronica J Bray William B McKinnon Jeffrey MMoore John R Spencer S A Stern W M Grundy Carly JAHowett Cristina M Dalle Ore Ross Beyer Alex H Parker Simon B Porter Amanda M Zangari Leslie A Young Cathy BOlkin Kimberly EnnicoInstitution(s) 1 Lowell Observatory 2 Lunar and PlanetaryInstitute 3 Lunar and Planetary Laboratory University ofArizona 4 NASA Ames Research Institute 5 SETI Institute 6Southwest Research Institute 7 Washington University in StLouis

10203 ndash Processes Modifying Cratered Terrains on

PlutoThe July encounter with Pluto by the New Horizons spacecraftpermitted imaging of its cratered terrains with scales as high as~100 mpixel and in stereo In the initial download of imagesacquired at 22 kmpixel widely distributed impact craters up to260 km diameter are seen in the near-encounter hemisphereMany of the craters appear to be significantly degraded or infilledSome craters appear partially destroyed perhaps by erosion such asassociated with the retreat of scarps Bright ice-rich depositshighlight some crater rims andor floors While the crateredterrains identified in the initial downloaded images are generallyseen on high-to-intermediate albedo surfaces the dark equatorialterrain informally known as Cthulhu Regio is also densely crateredWe will explore the range of possible processes that might haveoperated (or still be operating) to modify the landscape from that ofan ancient pristinely cratered state to the present terrains revealedin New Horizons images The sequence intensity and type ofprocesses that have modified ancient landscapes are among otherthings the record of climate and volatile evolution throughoutmuch of the Plutorsquos existence The deciphering of this record will bediscussed This work was supported by NASAs New Horizonsproject

Author(s) Jeffrey M Moore Alan D Howard Oliver LWhite Orkan M Umurhan Paul M Schenk Ross A Beyer William B McKinnon Kelsi N Singer John Spencer S AStern H A Weaver Leslie A Young Kimberly Ennico CathyB OlkinInstitution(s) 1 Johns Hopkins University Applied PhysicsLaboratory 2 Lunar and Planetary Institute 3 NASA AmesResearch Center 4 Southwest Research Institute 5 University ofVirginia 6 Washington University

10204 ndash In Charons Shadow Analysis of the UV SolarOccultation from New HorizonsObservations of Charon Plutos largest moon have so far yieldedno evidence for a substantial atmosphere However during theflyby of New Horizons through the Pluto-Charon system the Aliceultraviolet spectrograph successfully acquired the most sensitivemeasurements to date during an occultation of the sun as NewHorizons passed through Charons shadow These observationsinclude wavelength coverage in the extreme- and far-ultraviolet(EUV and FUV) from 52 nm to 187 nm We will present theseresults from Alice and discuss their implications for an atmosphereon CharonThis work was supported by NASAs New Horizons project

Author(s) Joshua A Kammer S A Stern H A Weaver L A Young K A Ennico C B Olkin G R Gladstone M ESummers T K Greathouse K D Retherford M H Versteeg J W Parker A J Steffl E Schindhelm D F Strobel I RLinscott D P Hinson G L Tyler W W WoodsInstitution(s) 1 George Mason University 2 JHU AppliedPhysics Laboratory 3 Johns Hopkins University 4 NASA AmesResearch Center 5 Southwest Research Institute 6 SouthwestResearch Institute 7 Stanford University

10205 ndash Charonrsquos Color A view from New HorizonRalphMultispectral Visible Imaging CamerThe Multispectral Visible Imaging Camera (MVIC Reuter et al2008) is part of Ralph an instrument on NASArsquos New Horizonsspacecraft MVIC is the color lsquoeyesrsquo of New Horizons observingobjects using four bands from blue to infrared wavelengthsMVICrsquos images of Charon show it to be an intriguing place a far cryfrom the grey heavily cratered world once postulated RatherCharon is observed to have large surface areas free of craters and anorthern polar region that is much redder than its surroundingsThis talk will describe these initial results in more detail forexample is Charonrsquos redder pole caused by molecules that haveescaped Plutorsquos atmosphere only to be captured and frozen ontothe surface of Charonrsquos cold polar region where they haveundergone photolysis Charonrsquos global geological color variationswill also be discussed to put these results into their wider contextThis work was supported by NASArsquos New Horizons project

33

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4

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1 6 6 65 5 5 3

7 7 7 7

5

Author(s) Carly Jacqueline Amy Howett Cathy B Olkin William M Grundy Alex H Parker Kimberly Ennico Sol AlanStern Richard P Binzel Jason C Cook Dale P Cruikshank Cristina M Dalle Ore Alissa Earle Don E Jennings IvanLinscott Allen W Lunsford Joel Wm Parker SilviaProtopapa Dennis C Reuter Kelsi N Singer John R Spencer Con CC Tsang Anne J Verbiscer Hal A Weaver Leslie AYoungInstitution(s) 1 Applied Physics Laboratory 2 LowellObservatory 3 Massachusetts Institute of Technology 4 NASAAmes 5 NASA Goddard Space Flight Center 6 SouthwestResearch Institute 7 Stanford University 8 University ofMaryland 9 University of Virigina

10206 ndash The Chasmata and Montes of CharonThe New Horizons spacecraft made the first-ever high-resolutionobservations of Plutos largest moon Charon on 14 July 2015Those observations returned views of complicated topography onthis icy world in the outer solar system Charon posseses a series ofchasmata and fossae that appear to form an organized tectonic beltthat spans across the disk of the Pluto-facing hemisphere and mayextend beyond In addition there are enigmatic isolatedmountains visible that are surrounded by depressions These inturn are surrounded by a relatively smooth plain broken byoccaisional rilles that stretches from these montes northward up tothe chasmata region We will discuss these features and more Thiswork was supported by NASAs New Horizons project

Author(s) Ross A Beyer Olivier Barnouin KimberlyEnnico Jeff Moore Francis Nimmo Cathy B Olkin PaulSchenk John Spencer S Alan Stern Hal A Weaver Leslie AYoungInstitution(s) 1 Applied Physics Laboratory Johns HopkinsUniversity 2 Lunar and Planetary Institute 3 NASA AmesResearch Center 4 SETI Institute 5 Southwest Research Institute6 University of California Santa Cruz

10207 ndash Investigating Surface Features on Nix andHydraThe LORRI (Cheng et al 2008Space Sci Rev 140 189) and MVIC(Reuter et al 2008Space Sci Rev 140 129) imagers on the NewHorizons (NH) spacecraft obtained spatially resolvedmeasurements of Nix and Hydra two of Plutos four small moonsNix was observed by LORRI in panchromatic light (350-850 nm) atresolutions up to 030 kmpix and by MVIC in color (400ndash550nm 540-700 nm 780ndash975 nm 860-910 nm the latter is centeredon a weak CH4 band) at resolutions up to 20 kmpix Hydra wasobserved by LORRI in panchromatic light at 11 kmpix and byMVIC in color at 46 kmpix The lossless versions of the imageswhich we will employ in our analysis are scheduled for downlink inSeptember and October 2015 After image deconvolutions whichtypically double the spatial resolution the NH images providehundreds to thousands of pixels across the surfaces of Nix andHydra We will present results on our searches for craterslineaments and other features on the surfaces of Nix and HydraWe will also present results on any correlations betweenmorphological features and color and albedo variations on thesurface This work was supported by NASAs New Horizons project

Author(s) Harold A Weaver O S Barnouin A F Cheng C M Ernst T R Lauer S A Stern C B Olkin K Ennico L A YoungInstitution(s) 1 Johns Hopkins APL 2 NASA Ames ResearchCenter 3 National Optical Astronomy Observatories 4 SouthwestResearch Institute

10208 ndash The Orbits and Masses of Plutos Satellitesafter New HorizonsBrozović et al (2015 Icarus 246 317) reported on Plutos mass andthe masses and numerically integrated orbits of Plutos satellitesCharon Nix Hydra Kerberos and Styx These were determinedvia a fit to an extensive set of astrometric mutual event and stellaroccultation observations over the time interval April 1965 to July2012 The data set contained the Hubble Space Telescope (HST)

observations of Charon relative to Pluto that were corrected for thePluto center-of-figure center-of-light offset due to the Pluto albedovariations (Buie et al 2012 AJ 144 15) Also included were all ofthe available HST observations of Nix Hydra Kerberos and StyxFor the New Horizons encounter with the Pluto system the initialsatellite ephemerides (PLU043) and the initial planet and satellitemasses were taken from the Brozović et al analysis During theNew Horizons approach the ephemerides and masses wereperiodically updated along with the spacecraft trajectory by the NewHorizons navigation team using imaging of the planet and satellitesagainst the stellar background In this work we report on ourpost-flyby analysis of the masses and satellite orbits derived from acombination of the original PLU043 data set the New Horizionsimaging data and HST observations acquired after 2012

Author(s) Robert A Jacobson Marina Brozovic MarcBuie Simon Porter Mark Showalter John Spencer S AlanStern Harold Weaver Leslie Young Kimberly Ennico CathyOlkinInstitution(s) 1 Johns Hopkins APL 2 JPL 3 NASA AmesResearch Center 4 SETI Institute 5 Southwest Research Institute

10209 ndash Orbital and Rotational Dynamics of PlutosSmall MoonsFour small moons Styx Nix Kerberos and Hydra orbit the centralbinary planet comprising Pluto and Charon Showalter andHamilton (Nature 522 45-49 2015) analyzed Hubble SpaceTelescope (HST) data from 2010-2012 to explore some of thedynamical consequences of orbiting a binary planet They notedevidence for a chaotic rotation of Nix and Hydra and identified apossible three-body resonance between Styx Nix and Hydra Werevisit the dynamics of the outer moons based on the latest datafrom the New Horizons flyby As the spacecraft approached Plutothe LORRI camera regularly imaged the moons over a period of~100 days This data set will make it possible to derive light curvesand rotation rates unambiguously something that has not beenpossible from the sparsely sampled HST data It also extends thetime baseline of the orbit determinations by several yearsproviding a more precise test of the proposed orbital resonancesWe will discuss the latest measurements and their dynamicalimplications for the evolution of the Pluto system This work wassupported by NASAs New Horizons project

Author(s) Mark R Showalter John R Spencer Simon BPorter Douglas P Hamilton Richard P Binzel S Alan Stern Harold A Weaver Cathy B Olkin Leslie A Young KimberlyEnnicoInstitution(s) 1 Applied Physics Lab 2 MIT 3 NASA AmesResearch Center 4 SETI Institute 5 Southwest Research Institute6 University of Maryland

10210 ndash Shapes and Poles of the Small Satellites ofPlutoPluto-Charon is a binary dwarf planet surrounded by four muchsmaller satellites Styx Nix Kerberos and Hydra (in order ofincreasing distance from the barycenter) These satellites werediscovered with the Hubble Space Telescope which also showedthat their orbits are nearly circular around the system barycenterand coplanar to the central binary NASAs New Horizonsspacecraft flew through the Pluto system on July 14 2015 andobtained the first resolved images of all four small satellites Wewill present initial models for the shapes and densities of the smallsatellites determined from both those resolved images and earlierunresolved images as well as measurements of the rotational polesof small satellites at the time of the Pluto encounter This work wassupported by the NASA New Horizons Project

6 62 6 4

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5

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1 5 53

6

Author(s) Simon B Porter Mark R Showalter John RSpencer H A Weaver Richard P Binzel Douglas P Hamilton S A Stern Catherine B Olkin Leslie A Young KimberlyEnnicoInstitution(s) 1 Johns Hopkins University Applied PhysicsLaboratory 2 Massachusetts Institute of Technology 3 NASAAmes Research Center 4 SETI Institute 5 Southwest ResearchInstitute 6 University of Maryland

10211D ndash Stability of coorbital objects around thePluto-Charon binaryThe Pluto-Charon binary system is dynamical interesting with itsunusual retinue of four small moons The system is relatively fullwith few remaining stable locations for additional moons onuninclined circular orbits most of these are Trojan(TadpoleHorseshoe) orbits (Pires et al 2011 Porter and Stern2015)In this work we study the coorbital region of each moon with longtime integrations taking into account the gravitational effects of thesatellites Charon Styx Nix Kerberos and Hydra We numericallysimulate a sample of 10000 test particles initially located randomlyaround each moons orbit All test particles start on nearly circularand uninclined orbits and are followed for 5000 years The resultsof our numerical simulations show stable coorbital objects ndash bothTadpoles and Horseshoes ndash for each of the small moonsHorseshoe orbits are most common at all moons although Hydraalso has a sizeable population of Tadpole orbits We also findinteresting cases where the orbits switch from L Tadpoles toHorseshoes and even to L Tadpoles These transitioning orbitscomprise less than 1 of coorbital objects at all moons and aremost common at Styx We have also tested two different models forthe system i) Pluto and Charon as independent bodies ii) A singlecentral body with the combined mass of Pluto-Charon and aneffective J coefficient Preliminary results show only minordifferences between the two models indicating that the binary doesnot have a strong effect on coorbital motion We have alsoinvestigated eccentric and inclined orbits and will report on ourfindings

Author(s) Andre Amarante Luiz Douglas P HamiltonInstitution(s) 1 University of Maryland

103 ndash Ceres Jubilee and Vested Interests10301 ndash Interior Evolution of Ceres Revealed by DawnDawnrsquos exploration of Ceres has revealed its geophysicalcharacteristics informing the processes that have shaped it Dawnhas determined the average diameter of Ceres to be 940 kmsmaller than the previously estimated 975 km [1] This implies adensity of 2160 kgm indicating that Ceres is less differentiatedthan predicted [2] The low-degree gravity field is consistent withthe body being in hydrostatic equilibrium and the magnitude of Jimplies some central condensation Ceresrsquo entire surface iscratered implying the lack of a thick (10rsquos of km) water ice layer atthe surface Variability in Ceresrsquo crater morphology indicates thatthe near-surface layer has variable strength and rheology likelydue to heterogeneity in the near-surface mixture of rock ice andsalt The lack of a number of expected large impact basins on Cerescan be interpreted to be the result of viscous relaxation resurfacingor a combination of both These data provide insights into Ceresrsquothermal evolution and mechanical properties which appear to beunique to this warm icy body[1] Thomas P C et al Differentiation of the asteroid Ceres asrevealed by its shape Nature 437 224ndash226 2005 [2] McCord etal Ceres Its Origin Evolution and Structure and Dawnrsquos PotentialContribution Space Sci RevDOI 101007s11214-010-9729-9 2011

Author(s) Carol A Raymond Ryan S Park Alex SKonopliv Michael T Bland Simone Marchi Julie C Castillo-Rogez Thomas B McCord Ralf Jaumann Christopher TRussell Thomas H PrettymanInstitution(s) 1 Bear Fight Institute 2 DLR 3 IGPPUCLA 4Jet Propulsion Laboratory California Institute of Technology 5Planetary Science Institute 6 SwRI 7 USGS Astrogeology ScienceCenter

10302 ndash Dawn at Ceres reveals an ammoniatedsurfaceThe Visible and Infrared Mapping Spectrometer (VIR) on board theDawn spacecraft has observed Ceresrsquo surface and acquired spectra(05 to 5 microm) since January 2015 Here we report the average Ceresspectrum including the important spectral range (26-29 microm)previously precluded from (telescopic) measurements due totelluric atmospheric absorptions The VIR data confirm that thesurface is very dark with an average albedo of 0090 plusmn0006 at 055microm consistent with Hubble Space Telescope data (Li et al Icarus2006) and contains no prominent absorption features in the visibleand near-Infrared at wavelengths less than 25 microm Ceresrsquo averagespectrum however is characterized by a prominent diagnosticabsorption band at 27 microm along with weaker absorption bandsobserved between 305-31 33-34 and 39-4 microm We modeled thenew VIR spectra of Ceres with various ices meteorites silicatescarbonates and hydrates using Hapke theory Results of thespectral modeling indicate that extensive water ice is not present inspectra representing the typical surface acquired to date atrelatively low spatial resolution (lt11 kmpixel) The best fit isobtained with a mixture of ammoniated phyllosilicates mixed withother clays Mg-carbonates serpentine and a strongly absorbingmaterial such as magnetite (De Sanctis et al Nature 2015 inreview) The presence of ammonia-bearing materials in the crustacross much of the surface has implications for the origin of Ceresand its internal structure and evolution At the time of thispresentation the Dawn spacecraft will have also completed its highaltitude mapping orbit to look for anticipated small-scalemineralogy variations across this remarkable dwarf planetAcknowledgements VIR is funded by the Italian SpaceAgencyndashASI and was developed under the leadership of INAFRome-Italy The instrument was built by Selex-Galileo Florence-Italy The analyses are supported by ASI NASA and the GermanSpace Agency Enabling contributions from the Dawn InstrumentOperations and Science Teams are gratefully acknowledged

Author(s) Carle M Pieters Maria Cristina De Sanctis Eleonora Ammannito Andrea Raponi Jean-Philippe Combe Thomas B McCord Harry McSween Lucy A McFadden Simone Marchi Fabrizio Capaccioni Maria Teresa Capria Giacomo Carrozzo Mauro Ciarniello Andrea Longobardo Sergio Fonte Michelangelo Formisano Alessandro Frigeri Marco Giardino Gianfranco Magni Enersto Palomba FedericoTosi Diego Turrini Francesca Zambon Ralf Jaumann William Feldman Thomas Prettyman Michael Toplis Carol ARaymond Christopher T RussellInstitution(s) 1 Bear Fight Institute 2 Brown Univ 3 DLR 4IAPS INAF 5 JPLCalTech 6 NASA Goddard 7 ObservatoireMidi Pyreacuteneacutees 8 PSI 9 UCLA 10 Univ Tenn

10303 ndash The Origin of Dwarf Planet CeresConstrained by DawnThe Dawn spacecraft has acquired important clues regarding theorigin of dwarf planet Ceres The surface composition ischaracterized by a prominent absorption band at 27 micron that isbest explained by the presence of ammoniated phyllosilicates (DeSanctis et al 2015) while the average density indicates a bulk watercontent of 30-40 The occurrence of widespread smooth terrainsmarked by a flat topography and few superposed craters associatedwith a large 290-km crater is best explained by the present of lowviscosity material mobilized by the impact energy (Marchi 2015)Such low viscosity material is compatible with an ice-rich outershell whose melting temperature is reduced by the presence of saltsandor ammonia hydrates Such inferred internal structure couldalso explain the lack of impact structures larger than about 400 km

5 45 1 2 6

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which may have relaxed leaving no obvious signatures in imagingdataThe presence of ammoniated phyllosilicates points toward thepresence of ammonia available in Ceres makeup Ammonia isrelatively rare among meteorites due to its high volatility at typicalmain belt temperatures thus indicating a potential contribution ofmaterial from the colder outer solar systemTwo main scenarios emerge Either Ceres formed in the trans-neptunian disk and subsequently was captured in the main belt orit formed close to its current position with a late addition ofmaterial drifting from the outer solar system The two scenariosimply rather different collisional evolution therefore Cerescratering record can potentially help to discriminate the more likelyevolution As craters are susceptible to degradation due to internalheat flow terrain properties and superposed cratering here we willevaluate the evidence for and against these formation scenarios bytaking into account the latest digital terrain models and gravity dataacquired by DawnDe Sanctis et al submitted July 2015Marchi S IAU General Assembly August 2015

Author(s) Simone Marchi Cristina De Sanctis DavidOBrien Eleonora Ammannito Julie Castillo-Rogez RalfJaumann Paul Schenk Carol Raymond Christopher Russell Ryan ParkInstitution(s) 1 DLR 2 INAF 3 JPL 4 LPI 5 PSI 6Southwest Research Institute 7 UCLA

10304 ndash Photometric Properties of Ceres and theOccator Bright SpotsDawn discovered several extremely bright spots on Ceres the mostprominent of which is located inside the Occator crater that is atleast 4-5 times brighter than the average Ceres Interestingly thesebright spots are located in relatively young craters that are at thelongitudes corresponding to the maximum water vapor observed bythe Herschel Space Observatory suggesting possible correlationwith water sublimation on Ceres We used the multi-color imagingdata collected by the Dawn Framing Camera to analyze the globalphotometric properties of Ceres and the bright spots especiallythose located inside the Occator crater Our objectives are todetermine the albedo and other light scattering properties of thebright spots on Ceres in the visible wavelengths in order tocharacterize their physical properties and find clues about theircomposition and possible formation mechanisms and thecorrelation with water sublimation The overall geometric albedo ofCeresrsquo global surface is 009-010 consistent with previous studiesThe Hapke roughness parameter is about 20deg close to many otherasteroids rather than 44deg as reported earlier Correspondingly thephase function of Ceres is less backscattering than previouslymodeled In contrast the geometric albedo of the bright spotsinside the Occator crater is 04-05 and the single scattering albedois 07-08 brighter than Vestarsquos global albedo but much darkerthan many icy satellites in the outer solar system The Hapkeroughness of the bright spots is much higher than Ceres averagesuggesting relatively loose deposit of materials rather than morecoherent or tightly packed materials The phase function of brightspots material is relatively more forward scattering than averageCeres possibly correlated to stronger multiple scattering due tohigh albedo resulting from more transparent materials The highestresolution images as of late-August 2015 show fine structureswithin the Occator bright spots We will also report the results fromthe albedo distribution within the bright spots

Author(s) Jian-Yang Li Lucille Le Corre Vishnu Reddy Mark V Sykes Andreas Nathues Carle M Pieters MauroCiarniello Diego Turrini Lucy A McFadden Carol ARaymond Christopher T RussellInstitution(s) 1 Brown University 2 Institute of Geophysicsand Planetary Physics University of California at Los Angeles 3Instituto di Astrofisica e Planetologia Spaziali INAF 4 JetPropulsion Laboratory California Institute of Technology 5 MaxPlanck Institute for Solar System Research 6 NASA GoddardSpace Flight Center 7 Planetary Science Institute

10305 ndash Spectrophotometry of the Ceres surfaceThe Dawn spacecraft is in orbit around dwarf planet Ceres Theonboard Framing Camera (FC) is mapping the surface through aclear filter and 7 narrow-band filters at various observationalgeometries and image resolutions Generally Ceres appearance inthese images is affected by shadows and shading effects whichobscure the intrinsic reflective properties of the surface By meansof photometric modeling we remove these effects and reconstructthe surface reflectance for each of the FC filters creating albedoand color maps in the process Considering these maps in unisonprovides clues to the physical nature and composition of thesurface and the dominant geologic processes that shape thesurface We assess the nature of color variations in the visiblewavelength range for Ceres globally We identify which terrainsexpress the dominant colors and investigate why some areas areexceptions to the rule By correlating the color over the surface withgeologic units we find an relatively strong enhancement of thereflectance towards the blue end of the visible spectrum for recentimpacts and their ejecta

Author(s) Stefan Schroumlder Stefano Mottola Uri Carsenty Ralf Jaumann Uwe Keller Katrin Krohn Jian-Yang Li Klaus-Dieter Matz Lucy McFadden Katharina Otto Frank Preusker Thomas Roatsch Frank Scholten Katrin Stephan RolandWagner Carol Raymond Chris RussellInstitution(s) 1 DLR 2 Goddard Space Flight Center 3 JPL 4PSI 5 Technische Universitaumlt Braunschweig 6 UCLA

10306 ndash First Spectral Coverage of two regions onCeres in the far-UVWe present the first spectral observations of Ceres in thefar-ultraviolet along with new measurements in the near-UV andvisible as measured by HSTSTIS as part of Cycle 22 in August-September 2015 The observations are motivated by earlybroad-band UV observations [1][2][3] suggesting a UV absorptioncentered near 260 nm along with a very strong increase in UVreflectance into the far-UV (~160 nm) We have observed twocentral longitudes of Ceres ndash near 0degW and 120degW (this latter areaone of the regions in which Herschel detected water vapor) ndash usingthe G140L (~120-172 nm) G230L (~170-310 nm) and G430L(~300-570 nm) detectors We use the data to test a prediction ofgraphitized carbon on the surface and we look for signatures ofwater ice andor water vapor[1] Parker J W S A Stern P C Thomas M C Festou W JMerline E F Young R P Binzel L A Lebofsky (2002) Astron J123 549[2] Li et al (2006) Icarus 182 143-160[3] Rivkin A S J-Y Li R E Milliken L F Lim A J Lovell BE Schmidt L A McFadden B A Cohen (2011) Space Sci Rev 16395

Author(s) Amanda R Hendrix Faith Vilas Jian-Yang LiInstitution(s) 1 Planetary Science Institute

10307 ndash Ceresrsquo impact craters probes of near-surfaceinternal structure and compositionDawn Framing Camera images of Ceres have revealed the existenceof a heavily cratered surface Shape models derived from theseimages indicate that most (though not all) large craters are quitedeep up to 6 km for craters larger than 100 km in diameter Theretention of deep craters is not consistent with a simpledifferentiated internal structure consisting of an outer layercomposed solely of pure water ice (covered with a rocky lag)overlying a rocky core Here we use finite element simulations toshow that for Ceresrsquo relatively warm surface temperatures thetimescale required to completely flatten a crater 60-km in diameter(or greater) is less than 100 Myr assuming a relatively pure outerice layer (for ice grain sizes le 1 cm) Preserving substantialtopography requires that the viscosity of Ceresrsquo outer-most layer(25-50 km thick) is substantially greater than that of pure waterice A factor of ten increase in viscosity can be achieved byassuming the layer is a 5050 ice-rock mixture by volumehowever our simulations show that such an increase is insufficientto prevent substantial relaxation over timescales of 1 Gyr Only

6 25 7 3

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particulate volume fractions greater than 50 provide an increasein viscosity sufficient to prevent large-scale rapid relaxation Suchvolume fractions suggest an outer layer composed of frozensoilregolith (ie more rock than ice by volume) a very salt-richlayer or both Notably while most basins appear quite deep a fewrelatively shallow basins have been observed (eg Coniraya)suggesting that relaxation may be occurring over very longtimescales (eg 4 Ga) that Ceresrsquo interior is compositionally andspatial heterogeneous andor that temporal evolution of theinterior structure and composition has occurred If these shallowbasins are in fact the result of relaxation it places an upper limit onthe viscosity of Ceresrsquo outer-most interior layer implying at leastsome low-viscosity material is present and likely eliminating thepossibility of a purely rocky (homogeneous low density highporosity) interior

Author(s) Michael T Bland Carol Raymond Ryan Park Paul Schenk Tom McCord Vishnu Reddy Scott King MarkSykes Chris RussellInstitution(s) 1 Bear Fight Institute 2 Department ofGeoscience Virginia Tech 3 Lunar and Planetary Institute 4NASA JPL 5 Planetary Science Institute 6 University ofCalifornia Los Angeles IGPPEPSS 7 USGS Astrogeology

10308 ndash Geomorphological evidence for pervasiveground ice on Ceres from Dawn dataFive decades of observations of Ceres have explored the likelihoodthat the innermost dwarf planet boasts an ice rich bulkcomposition We report geomorphological evidence from DawnFraming Camera data suggesting that its surface has likely beenshaped by surface andor shallow subsurface ice includingpossible evaporative and flow processes within silicate-icemixtures Here we highlight three classes of features that possessstrong evidence for ground ice First ubiquitous craters withscallop-shaped rims in some cases ldquobreachedrdquo are characterized bymass wasting processes and by the recession of crater walls inasymmetric patterns these could be influenced by processesanalogous to those in sublimating ice-rich terrain on Mars andthose formed by mass wasting in terrestrial glaciated regions Thedegradation of crater walls appears to be responsible for the nearlycomplete removal of some craters particularly at low latitudesSecond several high latitude high elevation craters feature lobedflows that emanate from cirque-shaped head walls and bearstrikingly similar morphology to flows on other ice-rich planetarysurfaces Possible similarities to terrestrial rock glaciers includelobate toes and indications of furrows and ridges consistent withflow of ice-cored or ice-cemented material Other lobed flowspersist at the base of crater walls and mass wasting features Manyflow features evidently terminate at ramparts Third there arefrequent irregular domes peaks and mounds within crater floorsthat depart from traditional crater central peaks or peak complexesIn some cases the irregular domes show evidence for high albedoor activity One possible formation scenario could include extrusionand refreezing of subsurface water forming domes in similarprocesses to ice lens formation in pingos The distribution of theseclasses of features including latitudinal variation in theirabundance andor appearance suggests that ground ice is a keycontroller of geology on Ceres and that ice content within thesurface and subsurface is spatially varied andor activated byenergetic events

Author(s) Britney E Schmidt Jennifer Scully Heather TChilton Kynan Hughson Hanna Sizemore Michael Bland Paul Schenk Andreas Nathues Thomas Platz David POBrien Shane Byrne Norbert Schorghofer EleonoraAmmanito Christopher T Russell Carol A Raymond MariaCristina DeSanctis Simone Marchi Jian-Yang Li LucilleLeCorre Vishnu Reddy Harald Hiesinger Ralf Jaumann Mark Sykes Thomas McCordInstitution(s) 1 Bear Fight Institute 2 DLR 3 GeorgiaInstitute of Technology 4 IFA University of Hawaii 5 INAF 6JPL 7 LPI 8 MPS 9 PSI 10 SWRI 11 UCLA 12 University ofArizona 13 University of Muenster 14 USGS

10309 ndash Thermal Stability of Ice on Ceres with Rough

TopographyThe dwarf planet Ceres may have an ice-rich crust and subsurfaceice exposed by impacts or endogenic activity would be subject tosublimation The ldquobright spotsrdquo recently discovered by the Dawnmission on the illuminated surface of Ceres have promptedspeculation regarding their possible icy composition and theyouthful age this might imply Furthermore sublimation of ice atthe surface or in the interior of Ceres could explain water vaporobserved on more than one occasion in the exosphere Weinvestigated the possible distribution and lifetimes of water ice andother volatiles on Ceres using detailed thermal models includingrealistic thermophysical properties and surface roughnessTopographic shadowing creates polar cold traps where a small butnon-negligible fraction (~04) of Ceres surface is perenniallybelow the ~110 K criterion for 1 Gyr of H O ice stability Theseareas are found above 60deg latitude Other molecules (CH OHNH SO CO ) may be cold-trapped in smaller abundances Amodel for the transport gravitational escape and photoionizationof H O molecules suggests net accumulation in the cold traps Atlatitudes 0deg - 30deg ice is stable under solar illumination only briefly(~10-100 yr) unless it has high albedo and thermal inertia inwhich case lifetimes of gt 10 yr are possibleBuried ice is stable within a meter for gt 1 Gyr at latitudes higherthan ~50deg An illuminated polar cap of water ice would be stablewithin a few degrees of the poles only if it maintained a high albedo(gt 05) at present obliquity If the obliquity exceeded 5deg in thegeologically recent past then a putative polar cap would have beenerased Finally a small hemispheric asymmetry exists due to thetiming of Ceres perihelion passage which would lead to adetectable enhancement of ice in the northern hemisphere if theorbital elements vary slowly relative to the ice accumulation rateOur model results are potentially testable during the Dawn sciencemission

Author(s) Paul O Hayne Oded AharonsonInstitution(s) 1 Jet Propulsion Laboratory 2 WeizmannInstitute of Science

10310D ndash Geophysics and geochemistry intertwinedModeling the internal evolution of Ceres Pluto andCharonLiquid water likely shaped dwarf planet evolution observations[12] and models [3-5] suggest aqueous alteration of silicates orvolatiles accreted by these worlds Driven by thermo-physicalsettings aqueous alteration also feeds back on dwarf planetevolution in unconstrained ways Can rocky dwarf planet corescrack increasing the water-rock interface Might radionuclides beleached into fluids changing the distribution of this chief heatsource What is the fate of antifreezes on which may hingelong-term liquid persistence Is volcanism favored or impededWhat are predicted cryomagma compositionsWe have modeled silicate core fracturing [6] geochemicalequilibria between chondritic rock and aqueous fluids [7] andprerequisites for cryovolcanism [8] These models coupled to anevolution code [3] allow us to study geophysicschemistryfeedbacks inside dwarf planetsIce-rock differentiation even partial [910] yields a rocky brittlecore cracked by thermal stresses liquid circulation through corecracks transports heat into the ice mantle yielding runawaymelting that quickly ceases once convection cools the mantle to itsfreezing point [6] Hot fluids can leach radionuclides at highwaterrock ratios (WR) NH antifreeze can turn intoNH -minerals at low WR [7] Volatile (chiefly CO) exsolutionenables explosive cryovolcanism [8] this may explain Plutorsquosyoung CO-rich Tombaugh RegioApplied to Ceres such models are consistent with pre-Dawn andDawn data [11] provided Ceres partially differentiated into a rockycore and muddy mantle [10] They suggest Ceresrsquo hydrated surface[2] was emplaced during a Al-fueled active phase and predict itsbright spots result from cryovolcanic fluids squeezed by mantlerefreezing and effusing through pre-existing subsurface cracks [11][1] Cook et al 2007 ApJ 6631406[2] Milliken amp Rivkin 2009 Nat Geosc 2258[3] Desch et al 2009 Icarus 202694

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[4] Castillo-Rogez et al 2010 Icarus 205443[5] Robuchon amp Nimmo 2011 Icarus 216426[6] Neveu et al 2015 JGR 120123[7] Neveu et al in prep[8] Neveu et al 2015 Icarus 24648[9] Rubin et al 2014 Icarus 236122[10] Travis et al 2015 46th LPSC abstr 2360[11] Neveu amp Desch in review

Author(s) Marc Neveu Steven J Desch Julie C Castillo-RogezInstitution(s) 1 Arizona State University 2 Jet PropulsionLaboratory

10311D ndash The geological evolution of asteroid Vestafrom Dawn orbital observations and meteoriteanalogsAsteroid Vesta is a survivor protoplanet and the knowledge it yieldsis essential to understand the early stages of planet formation Tosupport mineralogical characterization of its surface mineralogicaland near-IR (07-25 microm) analyses of 24 howardite-eucrite-diogenite meteorites were performed (Ruesch et al 2015) Therange of observation geometries within which the compositionalvariations can be distinguished from geometry effects weredetermined and empirical calibrations relating the position ofabsorption bands to average pyroxene compositions wereestablished Next the empirical calibrations were applied toreflectance spectra of Vesta from the Dawns near-IR spectrometer(VIR) revealing that Vestaacutes iron-poor terrains have a Fs Wopyroxene whereas iron-rich terrains have an average Fs Wo(Ruesch et al 2015) This confirms that despite a homogeneousregolith different terrains are preserved and formed during anearly magmatic period To further characterize Vestarsquos igneousprocesses a search for olivines near-IR signature was performedConcentrations of olivine-enriched areas were found in thenorthern hemisphere (Ruesch et al 2014a) corroborating otherstudies As such location was unexpected the geology of thenorthern was characterized with the Dawn Framing Cameraobservations (Ruesch et al 2014b) The hemisphere is composedof an ancient (pre-Veneneian epoch) densely cratered terrainpartly disrupted by a subdued tectonic system (Veneneian epoch)Olivine-enriched materials are exposed recently (Marcian epoch)by impacts and mass wasting but most of their parent lithologiesare probably the result of shallow magmatic activity during thepre-Veneneian The presence of olivine-enriched material in thiscontext and not as exposure of an olivine-rich mantle partlycontradicts many pre-Dawn concepts of Vestan differentiation Asan alternative to the HED parent body model few scenarios existfor Vestas early evolution and none provide consistentexplanation for the entire range of observations reported in thiscomprehensive mineralogical and geological study This revealsthat protoplanets experienced a complex differentiation processwhich is only partly understood

Author(s) Ottaviano RueschInstitution(s) 1 NASA Goddard Space Flight CenterORAU

104 ndash Planetary Rings10401 ndash Constraints on Chariklos rings from HST andVLT observationsIn June 2013 a stellar occultation revealed for the first time everthe presence of two dense and narrow rings around a small objectof the solar system the Centaur (10199) Chariklo (Braga-Ribas etal Nature 508 72 2014) This body follows an eccentric orbitbetween Saturn and Uranus with perihelion and apheliondistances of 131 and 185 AU Due to Uranus perturbations itsorbit is unstable on the very short time scale of ~10 Myr (Horner atal MNRAS 354 798 2004) The two rings (C1R and C2Rrespectively) have orbital radii a = 3906plusmn33 km and a =4048plusmn33 km and typical widths W ~65 km and W ~2km optical depths τ ~ 04 and τ ~ 006 with a gap of ~9km between the two Chariklos radius R ~ 120 km (Duffard et al

AA 568 A79 2014 Fornasier et al AA 518 L11 2014) implies thatthe ring system lies at 33-34 R farther away than the classicalRoche limit of 24 R that would be obtained for spherical ringparticles with the same density as CharikloTo better understand Chariklos surroundings and thus the originof the rings direct imaging of Chariklo has been performed usingHST and VLT with respectively 3 visits and 2 runs performedbetween April and August 2015 The HST images were obtainedwith the WFC3UVIS camera with filters F300X (250-350 nm)F475X (400-650 nm) and F350LP (300-1000 nm) and typical PSFsize of 30 milli-arcsec (mas) corresponding to about 300~km atChariklo Conversely the SPHERE high contrast instrument atESO VLT provided images in the near IR (Y J and H bands) withtypical expected PSF sizes of 30-40 mas (300-400~km atChariklo) The main goals of those observations were (1) obtaindirect images of the rings confirming their geometry and theirorientation (2) derive multi-wavelength photometry thusconstraining their composition (concerning in particular thepresence of water ice) (3) perform a deep search of small satellites(down to a few km in diameter) (4) faint dusty rings aroundChariklo (down to about τ ~10 -10 ) and (5) search possiblecometary jets or coma akin to what is observed around anotherCentaur Chiron (Ortiz et al AA 576 A8 2015) Premiminaryresults obtained from those observations will be presented

Author(s) Bruno Sicardy Marc W Buie Gustavo Benedetti-Rossi Felipe Braga-Ribas Julio I Bueno de Camargo ReneDuffard Jose Luis Ortiz Damien Gratadour ChristopheDumasInstitution(s) 1 Federal University of Technology(UTFPRDAFIS) - Paranaacute 2 Instituto de Astrofiacutesica de AndaluciacuteaCSIC 3 Observatoire de ParisLESIA and Univ Paris 6 4Observatorio Nacional 5 SWRI 6 Thirty-Meter-TelescopeInternational Observatory

10402 ndash Chariklos size shape and orientation fromstellar occultationsChariklo is the largest Centaur object known to date and it issurrounded by dense and narrow rings (Braga-Ribas et al Nature508 72 2014) The size shape and orientation of the central bodyare important parameters to better understand the dynamics of theringsIn that context we have analyzed three stellar occultations byChariklo and its main ring observed on June 3 2013 April 29 2014and June 28 2014 Elliptical limb fitting to Chariklorsquos main bodyoccultation chords has been performed where we denote a (respb) the semi-major (resp semi-minor) axis of the limb Preliminaryresults indicate that Chariklorsquos limb is elliptical with axes ratioba~089 We obtain a~133 km and b~119 km providing anequivalent radius of R =radic(ab)~126 km The rms dispersion ofthe fit about 4 km is compatible with local topographic features ona small icy body For comparison an equivalent radius of R =119plusmn5 km based on thermal data is given by Fornasier et al AA518 L11 2014 while Duffard et al AA 568 A79 2014 estimate a=122 km and b= 117 kmOur results are obtained under the simplifying assumption that themain ring is circular and that its center coincides with that ofChariklo Caveats and error bars will be discussed and dynamicalimplications will be presented In particular rough estimations ofthe ring apsidal precession rates will be given as well as constraintson Chariklos density

1 12

30 547 14

1

C1R C2RC1R C2R

C1R C1RC

CC

-5 -6

3 54 1 4

2 2 36

equiv

equiv

10

Author(s) Diane Beacuterard Bruno Sicardy Marcelo Assafin Felipe Braga-Ribas Julio Camargo Roberto Vieira Martins Rene Duffard Jose Luis Ortiz Colin Snodgrass EmmanuelJehin Joe Pollock Franccedilois Colas Jean Luc Dauvergne Jean Lecacheux Lucie Maquet Amanda A Sickafoose KarlLudwig Bath Wolfgang Beisker Rodrigo LeivaInstitution(s) 1 Ciel amp Espace 2 Federal University ofTechnology (UTFPRDAFIS) - Paranaacute 3 Institut dAstrophysiquede lUniversiteacute de Liegravege 4 Instituto de Astrofiacutesica de Andaluciacutea -CSIC 5 International Occultation Timing Association 6Observatoire de Paris - LESIA amp UPMC 7 Observatoire de ParisIMCCE UPMC CNRS 8 Observatoacuterio do Valongo - UFRJ 9Observatorio Nacional 10 Physics and Astronomy DepartmentAppalachian State University 11 South African AstronomicalObservatory amp MIT 12 The Open University

10403D ndashParticle Sizes in Saturnrsquos Rings from DiffractionSignals in Cassini UVIS Occultation DataSince its arrival at Saturn in 2004 the Cassini spacecraft hasilluminated many aspects of the planetrsquos extensive ring systemincluding its vast range of particle sizes Constraints on the particlesize distribution are critical for understanding the evolution of thering system Our investigation focuses on modeling diffractionsignals in occultation data from the Cassini Ultraviolet ImagingSpectrograph (UVIS) to measure the population of the smallestparticles in Saturnrsquos ringsOccultation data from Cassinirsquos Radio Science Subsystem and theVisual and Infrared Mapping Spectrometer also providemeasurements of the size distribution The amount of lightdiffracted by the occulting particles is a reflection of the ratio of thewavelength of light and the radius of the particles We can utilizethe diffraction signals at different wavelengths measured bydifferent instruments to describe the particle size distribution ofSaturnrsquos ringsThe UVIS wavelength bandpass 512-180 nm is the shortest ofthese instruments making it most sensitive to the smallestparticles We model the diffraction signals detected in stellaroccultation data at ring edges and find that Saturnrsquos outer A ringlacks any significant population of sub-mm particles but theaverage size of the smallest particles decreases from ~15 cm at theEncke Gap to ~4 mm at the outer edge of the A ring Diffractionspikes have also been identified at the edge of the B ring and atsharp edges of ringlets in the C ring and Cassini Divisionsuggestive of mm-sized particles throughout the rings We analyzesolar occultations by the F ring and sporadically detect diffractedlight indicating the population of sub-mm particles responsible forthe diffraction is transient or spatially variable Comparisons withimages from the Cassini Imaging Science Subsystem suggest thatthese diffraction signals coincide with nearby collisional events inthe F ring core This may indicate that such events release dustparticles producing a diffraction signature in the UVIS dataWe will present an overview of the concerted efforts to measure theparticle size distribution of Saturnrsquos rings and the recent resultsfrom our investigation of UVIS occultation data

Author(s) Tracy M Becker Joshua E Colwell Larry WEsposito Nicholas O Attree Carl D MurrayInstitution(s) 1 LASP University of Colorado Boulder 2Queen Mary University of London 3 University of Central Florida

10404 ndash A traveling feature in Janus spiral densitywavesEvery 40 years on 21 January the Saturnian co-orbital satellitesJanus and Epimetheus move radially and switch relative positionsThis swap also alters the locations of the resonances within therings corresponding to these moons In stellar occultations by the Aand B rings observed by the Cassini Ultraviolet ImagingSpectrographrsquos High Speed Photometer between 2005 and 2015we report the detection of many density-wave interferencestructures as a result of these orbital swapsMost prominent in the Janus 21 43 54 and 65 resonanceregions is a soliton-like traveling wave which propagates throughthe rings This wave moves at approximately twice the group

velocity of the A-ring spiral density waves and at a similar velocityto that of the Janus 21 density wave in the B ring The opticaldepth of the B ring near the Janus 32 spiral density wave is toogreat for it to be visible and no similar traveling features weredetected within three Mimas and Prometheus density waves

Author(s) Morgan Rehnberg Larry W Esposito Zarah LBrown Miodrag Sremčević Nicole AlbersInstitution(s) 1 CULASP

10405 ndash An analysis of the A rings outer edge probesSaturns interiorWe present a study of the behavior of the outer edge of Saturns Aring using images and occultation data obtained by the Cassinispacecraft over a period of 8 years from 2006 to 2014 More than5000 images and 150 occultations of the A ring outer edge areanalyzed Our fits confirm the expected response to the Janus 76Inner Lindblad resonance (ILR) between 2006 and 2010 whenJanus was on the inner leg of its regular orbit swap withEpimetheus During this period the edge exhibits a regular 7-lobedpattern with an amplitude of 128 km and one minimum alignedwith the orbital longitude of Janus as has been found by previousinvestigators However between 2010 and 2014 theJanusEpimetheus orbit swap moves the Janus 76 LR away fromthe A rings outer edge and the 7-lobed pattern disappearsIn addition to the perturbation forced by Janus we have identifieda variety of normal modes at the edge of the A ring with values ofm ranging from 3 to 18 and appropriate pattern speeds Thesemodes may represent waves trapped in resonant cavities at theedge (Spitale and Porco 2010 Nicholson et al 2014)We further identified some other signatures consistent withtesseral resonances that might be associated with inhomogeneitiesin Saturns interior This result is consistent with previous studies(Hedman et al 2009 2014) These signatures may provideinformation about differential rotation in Saturns interior

Author(s) Maryame El Moutamid Philip Nicholson PeterGierasch Richard French Joseph Burns Matthew Tiscareno Matthew Hedman Carl MurrayInstitution(s) 1 Cornell University 2 Queen Mary Universityof London 3 SETI Institue 4 University of Idaho 5 WellesleyCollege

10406 ndash Analysis and Dynamics of a SaturnianSatellite at the A Ring EdgeAn object found (Murray et al 2014) at the edge of Saturns A ringpresents a unique opportunity to investigate Charnoz et al (2010)ssuggestion that moonlets form in the rings as well as to conductdynamical studies near the ring edge We track this object inCassini images to learn its connection if any to Janus co-rotationand Lindblad resonances before and after the 2014 orbital shift ofJanus and Epimetheus We find that it may have undergone anabrupt eight-kilometer shift in semi-major axis in 2013 which isunexplained by resonant effects but may be due to a collision withsomething in or outside of the rings Furthermore we propose thepotential existence of another object near the ring edge whichwould obviate any change in the semi-major axis of Murraysobject Such an object may have been captured in co-rotationresonance with Janus between 2010 and 2014

Author(s) Christie J Trimble Maryame El Moutamid Philip D Nicholson Joseph A Burns Carl D Murray NicholasJ CooperInstitution(s) 1 Arizona State University 2 Cornell University3 Queen Mary University of London

10407 ndash Wisps in the outer edge of the Keeler GapSuperposed upon the relatively smooth outer edge of the KeelerGap are a system of wisps which appear to be ring materialprotruding inward into the gap usually with a sharp trailing edgeand a smooth gradation back to the background edge location onthe leading side (Porco et al 2005 Science) The radial amplitudeof wisps is usually 05 to 1 km and their azimuthal extent isapproximately a degree of longitude (~2400 km) Wisps are likely

6 6 82 9 9

4 4 123 10 7 1

6 7 115 5 6

3 31 2 2

1 11 1 1

1 11 5 1 3

4 2

1 22 2 3

3

11

caused by an interplay between Daphnis (and perhaps othermoons) and embedded moonlets within the ring though thedetails remain unclearAside from the wisps the Keeler Gap outer edge is the only one ofthe five sharp edges in the outer part of Saturns A ring that isreasonably smooth in appearance (Tiscareno et al 2005 DPS)with occultations indicating residuals less than 1 km upon apossibly non-zero eccentricity (RG French personalcommunication 2014) The other four (the inner and outer edgesof the Encke Gap the inner edge of the Keeler Gap and the outeredge of the A ring itself) are characterized by wavy structure atmoderate to high spatial frequencies with amplitudes ranging from2 to 30 km (Tiscareno et al 2005 DPS)We will present a catalogue of wisp detections in Cassini imagesWe carry out repeated gaussian fits of the radial edge location inorder to characterize edge structure and visually scan those fittededges in order to detect wisps With extensive coverage in longitudeand in time we will report on how wisps evolve and move bothwithin an orbit period and on longer timescales We will also reporton the frequency and interpretation of wisps that deviate from thestandard morphology We will discuss the implications of ourresults for the origin and nature of wisps and for the larger pictureof how masses interact within Saturns rings

Author(s) Matthew S Tiscareno Ethan G ArnaultInstitution(s) 1 Cornell University 2 SETI Institute

10408 ndash Strong orbital expansion of Saturnrsquos innerice-rich moons through ring torques and mutualresonances during their accretion from a massive ringSaturn has a diversity of moons with possibly diverse origins Titanlikely formed in Saturnrsquos sub-nebula (eg Canup amp Ward 2006)The small moons interior to Mimas are likely recent aggregates ofringrsquos material spreading through the Roche limit (Charnoz et al2010) The origin of the mid-size moons Mimas through Rhea isdebated Charnoz et al (2011) considered a massive ice-rock ringand strong tidal dissipation in Saturn (Q ~ 10 ) and found thatmoons out to Rhea could be spawned from such a ring Howeversuch a small value for Q for Saturn is debated In addition captureinto mutual Mean Motion Resonances (MMR) and resultingeccentricity growth (not included in the Charnoz et al (2011)model) could lead to orbital destabilization as the moons tidallyexpand over such large distances (Peale amp Canup 2015)Here we consider weak planetary tides (Q ge 10 ) and investigatewhether Mimas Enceladus and Tethys could have been spawnedfrom a massive ice ring (Canup 2010) In this scenario the rock inthese moons would be delivered by material from outside the ringseg by heliocentric impactors during the LHB (Canup 2013) Wehave expanded a numerical model developed to study the Moonrsquosaccretion (Salmon and Canup 2012 2014) which couples ananalytic Roche-interior disk model to the N-body code SyMBA(Duncan et al 1998) for satellites so that we can directly track theiraccretion and mutual interactions (including MMRs) as well astheir tidal interaction with the planet We consider an initially largeSaturn (Fortney et al 2007) and its progressive contraction whichimpacts the strength of tides and the location of the corotationresonance We perform simulations with and without Dione andRhea and study the influence of tidal dissipation into the moonsWe find that recoil of the moons due to ring torques together withcapture of moons into MMRs can produce a distribution similar tothat observed If tidal dissipation in the moons was weak we showthat even if the final moons have low eccentricity and inclinationthey experience a phase of high values that is subsequentlydamped by mutual collisions The latter seem to typically preservethe overall stability of the system

Author(s) Julien Salmon Robin M CanupInstitution(s) 1 Southwest Research Institute

10409 ndash Non-Linear Dynamics of Saturnrsquos RingsNon-linear processes can explain why Saturnrsquos rings are so activeand dynamic Ring systems differ from simple linear systems in twosignificant ways 1 They are systems of granular material whereparticle-to-particle collisions dominate thus a kinetic not a fluid

description needed We find that stresses are strikinglyinhomogeneous and fluctuations are large compared toequilibrium 2 They are strongly forced by resonances which drivea non-linear response pushing the system across thresholds thatlead to persistent statesSome of this non-linearity is captured in a simple Predator-PreyModel Periodic forcing from the moon causes streamlinecrowding This damps the relative velocity and allows aggregates togrow About a quarter phase later the aggregates stir the system tohigher relative velocity and the limit cycle repeats each orbitSummary of Halo Results A predator-prey model for ringdynamics produces transient structures like lsquostrawrsquo that can explainthe halo structure and spectroscopy This requires energeticcollisions (v asymp 10msec with throw distances about 200kmimplying objects of scale R asymp 20km)Transform to Duffing Eqn With the coordinate transformation z= M the Predator-Prey equations can be combined to form asingle second-order differential equation with harmonic resonanceforcingRing dynamics and history implications Moon-triggered clumpingat perturbed regions in Saturnrsquos rings creates both high velocitydispersion and large aggregates at these distances explaining bothsmall and large particles observed there We calculate thestationary size distribution using a cell-to-cell mapping procedurethat converts the phase-plane trajectories to a Markov chainApproximating the Markov chain as an asymmetric random walkwith reflecting boundaries allows us to determine the power lawindex from results of numerical simulations in the tidalenvironment surrounding Saturn Aggregates can explain manydynamic aspects of the rings and can renew rings by shielding andrecycling the material within them depending on how long themass is sequestered We can ask Are Saturnrsquos rings a chaoticnon-linear driven system

Author(s) Larry W EspositoInstitution(s) 1 Univ of Colorado

10410 ndash NanoRocks Experimental Study ofCollisional Damping and Aggregation at LowVelocitiesThe NanoRocks experiment on the International Space Stationconsists of 8 separate sample trays of particles from ~01 mm ndash 20mm in diameter that undergo collisional evolution Themicrogravity environment of the ISS allows collision speeds of lessthan 1 mms to be studied At these speeds the experimentreproduces the velocity dispersion found in unperturbed regions ofSaturnrsquos rings Observations of the rings from Cassini instrumentshint at aggregation and fragmentation of clumps depending on thelocal surface mass density particle size distribution and velocitydispersionThe eight NanoRocks samples include plastic beads copper glassand JSC-1 lunar regolith simulant The samples are shaken at 1minute intervals to provide initial collision velocities of a few cmsand video is recorded of the collisional evolution of the particlesamples We derive mean coefficients of restitution for thedifferent samples based on the damping of the mean velocitydispersion as well as tracking of individual particle trajectories Theevolution of the velocity distribution is consistent with a uniformrandom distribution of the coefficient of restitution independentof collision velocity This is consistent with results of Heiszligelmannet al (Icarus Vol 206 pp 424-430 2010) using larger icy particlesWe also find the onset of cluster formation at speeds of a fewmms We will present our results and discuss applications tomodels of the collisional evolution of Saturnrsquos rings

Author(s) Joshua E Colwell Julie Brisset Adrienne RDove Jessica Metzger Allison RasconInstitution(s) 1 University of Central Florida

10411 ndash Impact of Saturn Main Ring Mass oninterpretation of Pioneer 11 and Cassini SOI RadiationMeasurements Across the RingsThe Pioneer 11 (1979) and Cassini Orbiter (2004) missionsmeasured the energetic particle and gamma ray flux environments

2 1

3

4

1 1

23

1

1 11 1 1

12

across the A B and outer C rings of Saturn This radiationoriginates as secondary proton neutron electron and gamma rayemissions from the interaction of high-energy (gt 20 GeV) galacticcosmic ray protons and other ions with bulk ice material in therings and is sensitive to the surface mass density of the rings ThePioneer 11 analysis from the University of Chicago High EnergyTelescope published in 1985 was consistent with a average surfacedensity of about 50 gcm assuming pure water ice and a totalring mass of 27x10 Saturn masses (M ) This independently-derived value confirmed the post-Voyager result of 3x10 Mfrom radio and stellar occultations and from observed damping ofdensity waves in the rings Although some later ring models in theCassini mission era (2004 - present) allow for a greater mass by anorder of magnitude the latest density wave analysis from Cassiniindicates that the Pioneer-Voyager value may be correct GEANTradiation transport simulations have been performed to update thering radiation model and enable ongoing assessments of thePioneer 11 HET and Cassini MIMILEMMS responses to thisradiation The O gas production by radiation chemistry within thering material is also estimated as a function of ring mass forcomparison to Cassini and earlier measurements of the ringatmosphere and ionosphere More massive rings would producemore O

Author(s) John F Cooper Steven J Sturner Edward CSittler Jr Peter Kollmann Elias Roussos Robert E JohnsonInstitution(s) 1 Applied Physics Laboratory Johns HopkinsUniversity 2 Max Planck Institute for Solar System Research 3NASA Goddard Space Flight Center 4 University of Virginia

105 ndash Pluto System III--Plutos Atmosphere10501 ndash Radio Occultation Measurements of PlutorsquosAtmosphere with New HorizonsThe reconnaissance of the Pluto System by New Horizons includedradio occultations at both Pluto and Charon This talk will presentthe latest results from the Pluto occultation The REX instrumentonboard New Horizons received and recorded uplink signals fromtwo 70-m antennas and two 34-m antennas of the NASA DeepSpace Network - each transmitting 20 kW at 42-cm wavelength -during a diametric occultation by Pluto At the time this was writtenonly a short segment of data at occultation entry (193degE 17degS) wasavailable for analysis The REX measurements extendunequivocally to the surface providing the first direct measure ofthe surface pressure and the temperature structure in Plutorsquos loweratmosphere Data from occultation exit (16degE 15degN) are scheduledto arrive on the ground in late August 2015 Those observationswill yield an improved estimate of the surface pressure a secondtemperature profile and a measure of the diameter of Pluto with aprecision of a few hundred meters This work is supported by theNASA New Horizons Mission

Author(s) David P Hinson Ivan Linscott Len Tyler MikeBird Martin Paetzold Darrell Strobel Mike Summers WillWoods Alan Stern Hal Weaver Cathy Olkin Leslie Young Kimberly Ennico Randy Gladstone Tommy Greathouse JoshKammer Alex Parker Joel Parker Kurt Retherford EricSchindhelm Kelsi Singer Andrew Steffl Con Tsang MaartenVersteegInstitution(s) 1 Applied Physics Laboratory 2 George MasonUniversity 3 Johns Hopkins University 4 NASA Ames ResearchCenter 5 SETI Institute 6 Southwest Research Institute 7Stanford University 8 SwRI 9 University of Bonn 10University of Cologne

10502 ndash Discovery of Hazes in Plutos AtmosphereThe New Horizons spacecraft made the first reconnaissance of thePluto-Charon system on Jul 14 2015 The Long RangeReconnaissance Imager (LORRI) on New Horizons obtainedimages of Pluto and Charon on approach near closest approachand on departure The departure images obtained at high solarphase angles unexpectedly revealed that Plutorsquos atmosphere ishazy The haze in Plutorsquos atmosphere was detected in each of five

images obtained in two separate observations on Jul 14 and on Jul26 at solar phase angles of 167deg and 165deg respectively The hazeextends to altitudes of at least 150 km above Plutorsquos surface withevidence for layering andor gravity waves We will present thehaze observations and discuss derived physical properties andimplications for the atmosphere and its interactions with thesurface including estimates for the rate of deposition of hazeparticles on the surface of PlutoThis work was supported byNASAs New Horizons Project

Author(s) Andrew F Cheng Randy Gladstone MichaelSummers Alex Parker John Spencer Leslie Young HalWeaver Kim Ennico Cathy Olkin Alan SternInstitution(s) 1 George Mason 2 Johns Hopkins APL 3Southwest Research

10503 ndash Haze in Plutos atmosphere Results fromSOFIA and ground-based observations of the 2015June 29 Pluto occultationWe observed the 29 June 2015 occultation by Pluto from SOFIAand several ground-based sites in New Zealand Pre-eventastrometry (described in Zuluaga et al this conference) allowed usto navigate SOFIA into Plutos central flash (Person et al thisconference) Fortuitously the central flash also fell over the MtJohn University Observatory (Pasachoff et al this conference) Wecombine all of our airborne and ground-based data to produce ageometric solution for the occultation and to investigate the state ofPlutos atmosphere just two weeks before the New Horizonsspacecrafts close encounter with Pluto We find that theatmosphere parameters at half-light are unchanged from ourobservations in 2011 (Person et al 2013) and 2013 (Bosh et al2015) By combining our light-curve inversion with recent radiusmeasurements from New Horizons we find strong evidence for anextended haze layer in Plutos atmosphere See also Sickafoose etal (this conference) for an evaluation of the particle sizes andpropertiesSOFIA is jointly operated by the Universities Space ResearchAssociation Inc (USRA) under NASA contract NAS2-97001 andthe Deutsches SOFIA Institut (DSI) under DLR contract 50 OK0901 to the University of Stuttgart Support for this work wasprovided by NASA SSO grants NNX15AJ82G (Lowell Observatory)NNX10AB27G (MIT) and NNX12AJ29G (Williams College) andby the National Research Foundation of South Africa

Author(s) A S Bosh M J Person C A Zuluaga A ASickafoose S E Levine J M Pasachoff B A Babcock EW Dunham I McLean J Wolf F Abe E Becklin T ABida L P Bright T Brothers G Christie P L Collins R FDurst A C Gilmore R Hamilton H C Harris CJohnson P M Kilmartin M R Kosiarek K Leppik S ELogsdon R Lucas S Mathers C J K Morley P Nelson H Ngan E Pfuumlller T Natusch H-P Roumlser S Sallum M Savage C H Seeger H Siu C Stockdale D Suzuki T Thanathibodee T Tilleman P J Tristram J Van Cleve C Varughese L W Weisenbach E Widen M WiedemannInstitution(s) 1 AAVSO 2 Auckland Observatory 3 Earth ampSky Limited 4 Hazelwood Observatory 5 Lowell Observatory 6MIT 7 Mt John University Observatory 8 Nagoya University 9Sandy Ridge Observatory 10 South African AstronomicalObservatory 11 Southern Cross Observatory 12 StewardObservatory 13 Sydney University 14 US Naval Observatory15 UCLA 16 United States Antarctic Program 17 UniversitaumltStuttgart 18 University of Canterbury 19 University of NotreDame 20 USRA 21 Williams College

10504 ndash Investigation of particle sizes in Plutosatmosphere from the 29 June 2015 occultationThe 29 June 2015 observations of a stellar occultation by Plutofrom SOFIA and ground-based sites in New Zealand indicate thathaze was present in the lower atmosphere (Bosh et al thisconference) Previously slope changes in the occultation lightcurve profile of Plutorsquos lower atmosphere have been attributed tohaze a steep thermal gradient andor a combination of the twoThe most useful diagnostic for differentiating between these effects

2-8 S

-8 S

2

2

3 33 1 2 4

5 7 79 10 3 2

7 6 1 6 64 8 8

6 6 6 86 6 6 6

8

2 31 3 3 3

2 3 3 3

6 6 610 5 21 21

5 15 17 8 205 5 6 2 5

21 18 20 1415 18 6 2015 13 11 9 12 17 2 17 12

20 21 6 4 196 14 7 20

3 6 16 17

13

has been observing occultations over a range of wavelengths hazescattering and absorption are functions of particle size and arewavelength dependent whereas effects due to a temperaturegradient should be largely independent of observationalwavelength The SOFIA and Mt John data from this event exhibitobvious central flashes from multiple telescopes observing over arange of wavelengths at each site (Person et al and Pasachoff et althis conference) SOFIA data include Red and Blue observationsfrom the High-speed Imaging Photometer for Occultations (HIPOat ~ 500 and 850 nm) First Light Infrared Test Camera(FLITECAM at ~1800 nm) and the Focal Plan Imager (FPI+ at ~600 nm) Mt John data include open filter g r i and nearinfrared Here we analyze the flux at the bottom of the light curvesversus observed wavelength We find that there is a distinct trendin flux versus wavelength and we discuss applicable Mie scatteringmodels for different particle size distributions and compositions (aswere used to characterize haze in Plutos lower atmosphere inGulbis et al 2015)SOFIA is jointly operated by the Universities Space ResearchAssociation Inc (USRA) under NASA contract NAS2-97001 andthe Deutsches SOFIA Institut (DSI) under DLR contract 50 OK0901 to the University of Stuttgart Support for this work wasprovided by the National Research Foundation of South AfricaNASA SSO grants NNX15AJ82G (Lowell Observatory) PANNX10AB27G (MIT) and PA NNX12AJ29G (Williams College)and the NASA SOFIA Cycle 3 grant NAS2-97001 issued by USRA

Author(s) Amanda A Sickafoose A S Bosh M JPerson C A Zuluaga S E Levine J M Pasachoff B ABabcock E W Dunham I McLean J Wolf F Abe T ABida L P Bright T Brothers G Christie P L Collins R FDurst A C Gilmore R Hamilton H C Harris CJohnson P M Kilmartin M R Kosiarek K Leppik SLogsdon R Lucas S Mathers C J K Morley TNatusch P Nelson H Ngan E Pfuumlller H-Proeserirsuni-stuttgartde S Sallum M Savage C HSeeger H Siu C Stockdale D Suzuki T Thanathibodee T Tilleman P J Tristam J Van Cleve C Varughese L WWeisenbach E Widen M WiedemannInstitution(s) 1 Astronomical Society of Victoria 2 AucklandObservatory 3 Earth amp Sky Limited 4 Hazelwood Observatory5 Lowell Observatory 6 MIT 7 Mt John UniversityObservatory 8 Nagoya University 9 Sandy Ridge Observatory10 South African Astronomical Observatory 11 Southern CrossObservatory 12 Steward Obs 13 Sydney University 14 USNaval Observatory 15 UCLA 16 United States AntarcticProgram 17 Universitaumlt Stuttgart 18 University of Canterbury19 University of Notre Dame 20 USRA 21 Williams College

10505 ndash Central Flash Analysis of the 29 June 2015OccultationAfter an extensive prediction effort the 29 June 2015 occultationby Pluto was observed from both airborne (StratosphericObservatory for Infrared Astronomy - SOFIA) and numerousground-based telescopes (Bosh et al - this meeting) Real-timeprediction updates allowed placement of the SOFIA telescope withits four detectors deep within the central-flash region of theatmospheric occultation Fortuitously the Mount John UniversityObservatory (Lake Tekapo New Zealand) was also within thecentral-flash region (Pasachoff et al ndash this meeting) Thishappenstance resulted in multiple central-flash detections inseveral colors from each facility allowing direct comparison ofdifferent areas of the central-flash evoluteHere we examine and discuss the central-flash signatures from thehighest signal-to-noise light curves from each facility The relativeorientations and asymmetries in the central flashes allow us to usethem to tightly constrain the lower atmospheric ellipticity andorientation of likely winds with respect to Plutorsquos figure The ratioof the two separate central flashes is also a strong constraint on thegeometric solution for the full occultation data set and theabsolute height of the central flashes with respect to those expectedfor a clear isothermal atmosphere places constraints on hazedensities and thermal gradients in Plutorsquos lower atmosphere Wecan also compare the central-flash signatures in several colors(similar to Sickafoose et al ndash this meeting) to establish bounds on

haze-particle sizes in the lower atmosphereSOFIA is jointly operated by the Universities Space ResearchAssociation Inc (USRA) under NASA contract NAS2-97001 andthe Deutsches SOFIA Institut (DSI) under DLR contract 50 OK0901 to the University of Stuttgart Support for this work wasprovided in part by NASA grants SSO NNX15AJ82G (LowellObservatory) PA NNX10AB27G (MIT) and PA NNX12AJ29G(Williams College) as well as the National Research Foundation ofSouth Africa and the NASA SOFIA Cycle 3 grant NAS2-97001issued by USRA

Author(s) Michael J Person A S Bosh A A Sickafoose CA Zuluaga S E Levine J M Pasachoff B A Babcock E WDunham I McLean J Wolf F Abe E Becklin T A Bida L P Bright T C Brothers G Christie P L Collins R F Durst A C Gilmore R Hamilton H C Harris C Johnson P MKilmartin M R Kosiarek K Leppik S E Logsdon RLucas S Mathers C J K Morley T Natusch P Nelson HNgan E Pfueller H-P Roeser S Sallum M Savage C HSeeger H Siu C Stockdale D Suzuki T Thanathibodee TTilleman P J Tristram J Van Cleeve C Varughese L WWeisenbach E Widen M WiedemannInstitution(s) 1 AAVSO 2 Auckland Observatory 3 Earth ampSky Limited 4 Hazelwood Observatory 5 Lowell Observatory 6MIT 7 Mt John University Observatory 8 Nagoya University 9Sandy Ridge Observatory 10 Southern Cross Observatory 11Steward Observatory 12 Sydney University 13 UCLA 14 UnitedStates Antarctic Program 15 Universitaumlt Stuttgart 16 Universityof Canterbury 17 University of Notre Dame 18 USNO 19 USRA20 Williams College

10506 ndash Detection of Atmospheric CO on Pluto withALMAWe observed Pluto and Charon using the Atacama LargeMillimetersubmillimeter Array (ALMA) interferometer inNorthern Chile on June 122 and June 1315 2015 just one monthprior to the New Horizons flyby of the system The configuration ofALMA at the time provided ~03 resolution allowing separation ofemission from Pluto and Charon This project targeted multiplescience goals including a search for HCN in Plutos atmosphere [1]and high precision measurements of the individual brightnesstemperatures of Pluto and Charon [2] also presented at thismeeting Here we report the high SNR detection of carbonmonoxide in the atmosphere of Pluto The CO(3-2) rotational lineat 345796 GHz (867 μm) was observed with 117 kHz spectralresolution for 45 min (on-source) on each date providing~35mJychannel RMS CO emission was clearly detected on bothdays with a contrast of ~65 mJy above the Pluto continuum and~18 MHz FWHM linewidth with the combined integrated lineSNR gt50 The presence of CO in Plutos atmosphere is expecteddue to its presence as ice on the surface in vapor pressureequilibrium with the atmosphere (eg [3][4]) and it waspreviously detected at modest SNR in the near-IR using the VLT[5] A preliminary assessment based upon the CO line wings showsthe fractional abundance of CO is 500-750 ppm consistent withthat found in [5] Further the shape of the line core emission(assuming a constant CO mixing ratio) suggests that theatmospheric temperature rises quickly from the surface to~100-110 K in the altitude range 20-70 km but decreases abovethat falling to about 70 K by 200 km altitude A detailed lineinversion analysis will be performed and results presented[1] Lellouch et al this meeting [2] Butler et al this meeting [3]Owen et al (1993) Science 261 pp 745ndash748 [4] Spencer et al(1993) In Pluto and Charon pp 435ndash473 Univ of Arizona PressTucson [5] Lellouch et al (2011) AampA 530 L4

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Author(s) Mark Gurwell Emmanuel Lellouch BryanButler Arielle Moullet Raphael Moreno Dominique Bockeleacutee-Morvan Nicolas Biver Thierry Fouchet Darek Lis AlanStern Leslie Young Eliot Young Hal Weaver JeremieBoissier John StansberryInstitution(s) 1 Harvard-Smithsonian Center For Astrophysics2 Institut de Radio-Astronomie Millimeacutetrique 3 Johns HopkinsUniversity Applied Physics Laboratory 4 National RadioAstronomy Observatory - Charlottesville 5 National RadioAstronomy Observatory - Socorro 6 Observatoire de Paris 7Southwest Research Institute 8 Space Telescope Science Institute

10507 ndash Detection of HCN in Plutos atmosphereWe report on the first detection of hydrogen cyanide in Plutosatmosphere obtained with the ALMA interferometer ALMAobservations of the HCN(4-3) line at 354505 GHz were conductedon June 122 and June 1315 2015 at ~03 spatial resolutionseparating Pluto from Charon with a 234 kHz spectral samplingThe HCN line was detected on both dates with a ~100 mJycontrast and a ~075 MHz FWHM linewidth The narrow linewidthand the absence of Lorentzian wings indicate that most of the HCNresides in Plutos upper atmosphere As on Titan HCN is anexpected photochemical product in a N2-CH4 atmosphere Datainterpretation in terms of the HCN abundancevertical distributionand comparison with photochemical models will be presented

Author(s) Emmanuel Lellouch Mark Gurwell BryanButler Arielle Moullet Raphael Moreno Dominique Bockeleacutee-Morvan Nicolas Biver Thierry Fouchet Darek Lis AlanStern Leslie Young Eliot Young Hal Weaver JeremieBoissier John StansberryInstitution(s) 1 Harvard-Smithsonian Center For Astrophysics2 Institut de Radio-Astronomie Millimeacutetrique 3 Johns HopkinsUniversity Applied Physics Laboratory 4 National RadioAstronomy Observatory - Charlottesville 5 National RadioAstronomy Observatory - Socorro 6 Observatoire de Paris 7Southwest Research Institute 8 Space Telescope Science Institute

10508 ndash Plutos Extended Atmosphere New HorizonsAlice Lyman-α ImagingPlutos upper atmosphere is expected to extend several planetaryradii proportionally more so than for any planet in our solarsystem Atomic hydrogen is readily produced at lower altitudes dueto photolysis of methane and transported upward to become animportant constituent The Interplanetary Medium (IPM) providesa natural light source with which to study Plutos atomic hydrogenatmosphere While direct solar Lyman-α emissions dominate thesignal at 1216 nm at classical solar system distances thecontribution of diffuse illumination by IPM Lyman-α sky-glow isroughly on par at Pluto (Gladstone et al Icarus 2015) Hydrogenatoms in Plutos upper atmosphere scatter these bright Lyαemission lines and detailed simulations of the radiative transfer forthese photons indicate that Pluto would appear dark against theIPM Lyα background The Pluto-Alice UV imaging spectrograph onNew Horizons conducted several observations of Pluto during theencounter to search for airglow emissions characterize its UVreflectance spectra and to measure the radial distribution of IPMLyα near the disk Our early results suggest that these modelpredictions for the darkening of IPM Lyα with decreasing altitudebeing measureable by Pluto-Alice were correct Well report ourprogress toward extracting H and CH density profiles in Plutosupper atmosphere through comparisons of these data with detailedradiative transfer modeling These New Horizons findings will haveimportant implications for determining the extent of Plutosatmosphere and related constraints to high-altitude verticaltemperature structure and atmospheric escapeThis work was supported by NASAs New Horizons project

Author(s) Kurt D Retherford G Randall Gladstone SAlan Stern Harold A Weaver Leslie A Young Kimberly AEnnico Cathy B Olkin Andy F Cheng Thomas KGreathouse David P Hinson Joshua A Kammer Ivan RLinscott Alex H Parker Joel Wm Parker Wayne R Pryor Eric Schindhelm Kelsi N Singer Andrew J Steffl Darrell FStrobel Michael E Summers Constantine C C Tsang G LenTyler Maarten H Versteeg William W Woods Nathaniel JCunningham Werner CurdtInstitution(s) 1 Central Arizona College 2 George MasonUniversity 3 JHU Applied Physics Laboratory 4 Max PlanckInstitute for Solar System Research 5 NASA Ames ResearchCenter 6 Nebraska Wesleyan University 7 Southwest ResearchInst 8 Stanford University 9 The Johns Hopkins University

10509 ndash Escape of Plutos Atmosphere In SituMeasurements from the Pluto Energetic ParticleSpectrometer Science Investigation (PEPSSI)instrument on New Horizons and RemoteObservations from the Chandra X-ray observatoryThe escape rate of Plutos atmosphere is of significant scientificinterest The Pluto Energetic Particle Spectrometer ScienceInvestigation (PEPSSI) is a compact energy by time-of-flight(TOF) instrument developed to help address this science goalPluto is known to have an atmosphere and pre-encounter modelshave postulated a majority N composition with free escape of upto ~10 moleculessec The expected major ionization productnear Pluto is singly ionized N molecules with pickup energiessufficient to be measured with PEPSSI In the process of measuringthe local energetic particle environment such measurements canalso provide constraints on the local density of Plutos extendedatmosphere which along with plasma measurements from theSolar Wind Around Pluto (SWAP) instrument also on NewHorizons could allow the inference of the strengh and extent ofmass-loading of the solar wind due to Plutos atmosphere Plutosneutral atmosphere also provides a source population for chargeexchange of highly ionized minor ions in the solar wind such as OC and N This process allows these ions to capture one electronand be left in an excited state That state in turn decays with theemission of a low-energy (100 eV to 1 keV) X-ray Observations ofsuch solar wind charge exchange (SWCX) X-rays have been madein the past of the Earths geocorona and Marss extendedatmosphere The award of almost 40 hours of DirectorsDiscretionary Time (DDT) for observing Pluto with the ChandraX-ray observatory near the period of closest approach of NewHorizons to Pluto potentially enabled a remote determination ofPlutos global outgassing rate using the local solar wind flux asmeasured by the SWAP instrument Preliminary anaysis of datareturned from these observations reveal a definite interaction ofPluto with the solar wind but at a lower strength than had beenpredicted This work was supported by NASAs New Horizonsproject

Author(s) Ralph L McNutt Matthew E Hill Carey MLisse Peter Kollmann Fran Bagenal Stamatios M Krimigis David J McComas Heather A Elliott Scott J Wolk Darrell FStrobel Xun Zhu S A Stern H A Weaver L A Young KEnnico C B OlkinInstitution(s) 1 Harvard-Smithsonian Center for Astrophysics2 Johns Hopkins University 3 Johns Hopkins University AppliedPhysics Laboratory 4 Laboratory for Atmospheric and SpacePhysics University of Colorado 5 NASA Ames Research Center 6Southwest Research Institute 7 Southwest Research InstituteBoulder

10510 ndash First Results on Plutos Energetic ParticleEnvironment from the PEPSSI InstrumentThe New Horizons spacecraft flew by Pluto in July 2015 and passedthrough the wakes of Pluto and its largest moon Charon Plutointeracts with the solar wind via the magnetic fields created bycurrents in its ionosphere and the pick-up of charge-exchange ionsescaping from its atmosphere The PEPSSI instrument (PlutoEnergetic Particle Spectrometer Science Investigation) passedthrough this interaction region Closest approach distance to Pluto

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228

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was 11 Pluto radii inside the orbit of Charon PEPSSI measuresintensities of keV to MeV ions and can distinguish ions in the solarwind from ions originating from Pluto Plutorsquos energetic particleenvironment clearly stands out compared to the surrounding solarwind at these heliospheric distances Electrons in the same energyrange as the ions do not show a distinct signature throughout theflyby There is no indication in the particle observations for anintrinsic magnetic field of Pluto We will present an analysis of thedata that is downlinked throughout August and set them intocontext with measurements taken by PEPSSI in Jupiterrsquosmagnetotail in 2007 This work was supported by NASAs NewHorizons project

Author(s) Peter Kollmann M E Hill R McNutt H TSmith J Vandegriff M Kusterer L Brown D K Haggerty C M Lisse H A Elliott D Strobel F Bagenal E Sidrow DJ McComas M Horanyi E Zirnstein S M Krimigis KEnnico L A Young H A Weaver C B Olkin S A SternInstitution(s) 1 Johns Hopkins University 2 Johns HopkinsUniversity Applied Physics Laboratory 3 NASA Ames 4Southwest Research Institute 5 Southwest Research Institute 6University of Colorado Boulder

10511 ndash Photochemistry Ion Chemistry and HazeFormation in Plutorsquos AtmosphereThe detection of ethylene (C H ) and acetylene (C H ) in Plutorsquosatmosphere provides important ground-truth observations forvalidating photochemical models of Plutorsquos atmosphere Theirdetection also confirms the production of precursor chemicalcompounds involved in the formation of tholins which are thoughtto give Plutorsquos surface its reddish color Photochemical modelspredict many other hydrocarbon and nitrile products currentlyundetected which may also be participants in tholin production onPlutorsquos surface or on atmospheric haze particles The observedatmospheric haze layer extending to altitudes of ~140 km abovePlutorsquos surface suggests a global and very robust process ofatmospheric particle nucleation growth and sedimentation ontoPlutorsquos surface The high altitude extent of the haze layer suggeststhat the nucleation process begins above the expected altituderange where hydrocarbons become supersaturated (below ~30 kmaltitude) This situation may be analogous to that in Titanrsquosatmosphere wherein nucleation and aerosol growth is directlyrelated to large negative ion production In the case of Pluto thismeans that nucleation may occur at altitudes as high as 1200 kmaltitude where ionization in Plutorsquos atmosphere peaks In thispaper we discuss these processes and their implications for hazeformation in Plutorsquos atmosphere and its deposition onto Plutorsquossurface This work was supported by NASAs New Horizons project

Author(s) Michael E Summers S A Stern G RandalGladstone Leslie A Young C B Olkin H A Weaver A FCheng D F Strobel K A Ennico J A Kammer A HParker K D Retherford E Schindhelm K N Singer A JSteffl C C Tsang M H Versteeg T K Greathouse I RLinscott L G Tyler W W Woods D P Hinson J WParker J P Renaud M Ewell Cary M LisseInstitution(s) 1 Applied Physics Laboratory 2 George MasonUniv 3 NASA Ames Research Center 4 Southwest ResearchInstitute 5 Stanford University 6 The Johns Hopkins University7 The SETI Institute

10512 ndash A 3D Global climate model of the Plutoatmosphere to interpret New Horizons observationsincluding the N CH and CO cycles and theformation of organic hazesTo interpret New Horizons observations and simulate the Plutoclimate system we have developed a Global Climate Model (GCM)of Plutos atmosphere In addition to a 3D dynamical core whichsolves the equations of meteorology the model takes into accountthe N condensation and sublimation and its thermal anddynamical effects the vertical turbulent mixing the radiativetransfer through methane and carbon monoxide molecularthermal conduction and a detailed surface thermal model withdifferent thermal inertia for various timescales (diurnal seasonal)

The GCM also includes a detailed model of the CH and CO cyclestaking into account their transport by the atmospheric circulationand turbulence as well as their condensation and sublimation onthe surface and in the atmosphere possibly forming methane iceclouds The GCM consistently predicts the 3D methane abundancein the atmosphere which is used as an input for our radiativetransfer calculationBecause of the radiative timescales the surface thermal inertia andthe slow evolution of the methane cycle the model takes morethan 20 years to become insensitive to the assumed atmosphericinitial states We typically start our simulations in 1975 to simulate2015 but remain sensitive to the assumed initial ices distributionand seasonal thermal inertia map The simulated thermal structureand waves can be compared to the New Horizons occultationsmeasurements As observed the longitudinal variability is verylimited for fundamental reasonsIn addition we have developed a 3D model of the formation oforganic hazes within the GCM It includes the different steps ofaerosols formation as understood on Titan photolysis of CH inthe upper atmosphere by the Lyman-alpha radiation production ofvarious gaseous precursor species conversion into solid particlesthrough chemistry and aggregation processes and gravitationalsedimentation Significant amount of haze particles are found to bepresent at all latitudes up to 100 km However if N ice is alreadycondensing in the polar night most of the haze tend to accumulatein the winterfall hemisphere because of the transport of the hazeprecursors and aerosols by the condensation flow

Author(s) Francois Forget Tanguy Bertrand MelanieVangvichith Jeremy LeconteInstitution(s) 1 LMD IPSL CNRS Universiteacute P et M Curie

106 ndash The Asteroid Composition ChannelFrom Soft Rock to Heavy Metal10601 ndash NIR spectral and mineralogic studies of nineVp-type asteroids 7 likely Vestoids and 2 likely newouter belt basaltic asteroid candidatesNine additional Vp-type asteroids as candidate basaltic asteroidswere observed at the NASA Infrared Telescope Facility (IRTF) fromJanuary 15-19 2015 UT as part of a continuing NASA PlanetaryAstronomy Program grant to better characterize the abundance anddistribution of basaltic asteroids in the main asteroid belt TheVp-type asteroids which are classified based on Sloan ugriz colorsand the subsequent coarse visible-wavelength spectra that resultsincludes (2168) Swope (3715) Stohl (3849) Incidentia (5754)1999 FR2 (10666) Feldberg (19165) 1991 CD (34698) 2001 OD22and (36118) 1999 RE135 The first seven of these Vp-type asteroidseither reside near (4) Vesta dynamical space or are located withinthe 31 mean-motion resonance The latter two Vp-type asteroidsare located beyond the 31 mean-motion resonance NIR spectrawere obtained using SpeX in prism mode (07 to 25 microns) at theparallactic angle using the 08 arsec slit Seven of the Vp-typeasteroids were observed on two nights while (2168) Swope wasobserved on three nights and (19165) 1991 CD was observed on asingle night Average near-infrared (NIR) reflectance spectra of theasteroids were analyzed using MATLAB-based (Reddy et al 2011)and IDL-based SARA (Lindsay et al 2013) routines to isolateabsorption features and measure band centers band areas andband depths Temperature corrections were applied to band centersto allow comparison with HED meteorite band parameters Initialresults indicate that all nine asteroids exhibit similar spectral bandcenters and Band Area Ratios (BAR) across different nights withlittle or no significant variation The MATLAB and SARA analysisroutines also produce similar results for all nine asteroids All nineasteroids exhibit BAR values consistent with basaltic achondrites orexhibit larger values beyond the BAR zone as found in Gaffey et al(1993) WISE-derived albedos for these asteroids range from24-50 Initial analysis indicates that the seven inner-belt Vp-typeasteroids are likely Vestoids and are associated with (4) Vesta while(34698) and (36118) are new candidates for outer-belt basalticasteroids

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Author(s) Paul S Hardersen Vishnu Reddy MattNowinski Maggie DievendorfInstitution(s) 1 Planetary Science Institute 2 Univ of NorthDakota

10602 ndash Are near-Earth Vestoids volatile-richasteroidsAsteroids that are linked to carbonaceous chondrite meteoritesexhibit an absorption feature at ~3 microm which is generallyattributed to hydroxyl- andor water-bearing materials Howeverrelatively weaker 3-microm features have been detected on some bodiesthat are not linked to carbonaceous chondrites For these bodiesthe 3-microm feature could be due to surficial OH implanted from solarwind or from emplacement of exogenically sourced carbonaceous(low albedo) material Such emplacement has been seen onasteroid (4) Vesta which was visited by NASArsquos Dawn spacecraftCarbonaceous chondrite impactors have been suggested as thesource of the exogenic low-albedo material on Vesta and the sourceof the event that created the older Veneneia basin on Vestarsquos southpole If the low-albedo material delivered to Vesta during theVeneneia-forming event were mixed with howarditic material toform Vestoids some of which were later transported to Earth-crossing orbits we would expect to detect this carbonaceousmaterial on these near-Earth Vestoids HED meteorites also showcarbonaceous chondrite clasts To test this hypothesis we haveobserved Vestoids in the 3-microm region using the long-wavelengthcross-dispersed (LXD 19ndash42-microm) mode of the SpeXspectrographimager at the NASA Infrared Telescope Facility(IRTF) Here we present high-quality 3-microm spectra of twoNear-Earth Vestoids (357439) 2004 BL which was observedduring close flyby of Earth January 2015 and (4055) Magellanwhich was observed in August 2015 This work has implications forboth the understanding of the origin of Vestoids and thecharacterization of the 3-microm region in spectra of near-EarthasteroidsThis research is supported by the USGS Shoemaker Fellowship andNASArsquos Near-Earth Object Observations Program Parts of thisresearch work was supported by the NASA Near-Earth ObjectObservations Program grant NNX14AL06G (PIReddy) NASAIRTF is operated by the University of Hawaii under CooperativeAgreement No NCC 5-538 with NASA Office of Space SciencePlanetary Astronomy Program

Author(s) Driss Takir Vishnu Reddy Juan A Sanchez Lucille Le Corre Paul S HardersenInstitution(s) 1 Planetary Science Institute 2 US GeologicalSurvey 3 University of North Dakota

10603 ndash Early Evolution of the Main Belt Informed bythe Compositional Diversity of Basaltic AsteroidsWe present near-infrared (078-245 micron) reflectance spectrafor eight outer main belt (a gt 25 AU) asteroids that have beentaxonomically classified as V-types based on visible wavelengthdata Three of these objects are spectrally distinct from allclassifications in the Bus-DeMeo spectral catalogue and thus couldrepresent either spectral end members of the V-type taxonomicclass or a small population of a new spectral type The remainder ofthe sample are classified as V- or R-type All of these asteroids aredynamically distinct from the Vestoid family implying that theyoriginated from differentiated planetesimals which have since beendestroyed or ejected from the solar system The 1- and 2-μm bandcenters of all objects determined using Modified Gaussian Modelfits were compared to those of 47 Vestoids and fifteen HEDmeteorites of known composition Formulas relating Band 1 andBand 2 centers to the pyroxene mineralogies of these asteroidswere derived from the sample of HED meteorites and used todetermine the Fs numbers of all asteroids The Fs numbers of thefive outer belt V- and R-type asteroids are on average between fiveand ten molar percent lower than those of the Vestoids implyingthat these objects formed in a more reducing environment thanVesta Given the complex evolution of oxygen fugacity in the solarnebula these compositional results suggest that these outer beltbasaltic asteroids formed either interior to Vesta and were laterscattered to the outer belt or formed at a later epoch than Vesta

Author(s) Thomas Leith Nicholas Moskovitz RhiannonMayne Francesca DeMeo Driss TakirInstitution(s) 1 Astrogeology Science Center United StatesGeological Survey 2 Lowell Observatory 3 MassachusettsInstitute of Technology 4 Monnig Meteorite Collection TexasChristian University

10604 ndash Finding metal-rich asteroids ndash aNEOShield-2 StudyThe 12 km diameter Barringer Crater in Arizona was produced byan impact of a metallic asteroid whereas the impact of a similarsized stony asteroid in 1908 over Tunguska Russia resulted in alarge airburst but no craterStudies of the metal content of asteroids are relevant not only toestimations of their potential to wreak devastation on impactingthe Earth but also for theories of their origins and nature andpossibly in the future for endeavors in the field of planetaryresourcesHowever the reflection spectra of metallic asteroids are largelyfeatureless which makes it difficult to identify them and relativelyfew are therefore known With reference to radar albedos andtaxonomic classifications we showed (Harris and Drube 2014)that data from the WISENEOWISE thermal-infrared survey(Wright et al 2010 Mainzer et al 2011a) fitted with a simplethermal model (NEATM Harris 1998) can reveal asteroids likelyto be metal rich based on the NEATM fitting parameter η whichcarries information on thermal inertiaTo further explore the dependence of η and thermal inertia ontaxonomic type we are continuing analyses of WISENEOWISEdata and expanding them to include IRAS data (Tedesco et al2002) We are calculating the angle between the spin vector andthe solar direction θ for different sightings of asteroids havingknown spin vectors The η values of objects with high thermalinertia and moderate to high spin rates should depend strongly onθ whereas those with low thermal inertia andor low spin ratesshould not We will present the latest results of our work andprovide a demonstration of its potentialReferencesHarris A W and Drube L 2014 Ap J Letters 785 L4Harris A W 1998 Icarus 131 291Mainzer A et al 2011a ApJ 743156Tedesco E F et al 2002 Astron J 123 1056Wright E L et al 2010 AJ 140 1868AcknowledgementsThe research leading to these results has received funding from theEUs Seventh Framework Programme (FP72007-2013) undergrant agreement no 282703 (NEOShield Project) and the EUrsquosHorizon 2020 Programme under grant agreement no 640351(NEOShield-2 Project)

Author(s) Line Drube Alan W HarrisInstitution(s) 1 German Aerospace Center

10605 ndash Near Earth Asteroid (4015) Wilson-Harrington a Possible Source of Meteorites from thePolana or the Themis FamilyNear-Earth asteroid (4015) Wilson-Harrington is particularlyinteresting for a number of reasons It has displayed cometaryactivity hence its designation as comet 107P and since Wilson-Harrington likely originated in the main asteroid belt (Bottke at al2002a) it could also be called a Main-belt Comet This object hasbeen linked to fireballs capable of producing recoverable meteorites(Campins and Swindle 1998) and it is a potential target ofspacecraft missions We have carried out spectroscopic anddynamical studies of Wilson-Harrington and we narrow its likelyorigin to either the Polana or the Themis asteroid families Wepresent new visible and near-infrared spectra of Wilson-Harrington that show significant similarities with members of theThemis and Polana families These spectral parallels are consistentwith dynamical arguments that connect the current orbit ofWilson-Harrington with each of these two families However it isnot clear at this time which of the families is the more likely originfor Wilson-Harrington Our work also has implications on sourcesof primitive meteorites

2 12 2

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Author(s) Humberto Campins Javier Licandro Julia deLeoacuten Noemiacute Pinilla-Alonso Vania Lorenzi Victor Ali-Lagoa Alessandro MorbidelliInstitution(s) 1 Fundacioacuten Galileo Galilei ndash INAF 2 Institutode Astrofiacutesica de Canarias ndash IAC 3 Laboratoire LagrangeObservatoire de la Cocircte drsquoAzur 4 Univ of Central Florida 5University of Tennessee

10606 ndash 3-microm spectroscopy of Near-Earth AsteroidsSearching for OHH O on small planetary bodiesNear-Earth asteroids (NEAs) are not expected to have OH andorH O ice on their surfaces because a) most accreted dry in theinner Solar System and therefore never contained hydratedmaterials and b) their relatively high surface temperatures shouldquickly drive OHH O off their surface However OHH O hasbeen detected on other anhydrous inner solar system objectsincluding the Moon and Vesta Possible mechanisms to explainOHH O on surfaces in the inner Solar System include productionvia solar wind interactions carbonaceous chondrite or cometaryimpact delivery or native OHH O molecules bound tophyllosilicates As these processes are active in near-Earth spacewe hypothesize that detectable levels of OHH O are present onNEAsThe OHH O feature can be comprised of an OH absorptionfeature centered near 27 μm and H O features near 29 and 31μm or a blend of both producing a relatively wide featurespanning 27 ndash 31 μm Analysis of the shape of the 3-microm featurecoupled with the observed NEA orbital parameters and albedoscan help distinguish between the possible sources of OHH OHere we present results of an ongoing observational program tomeasure spectra of NEAs in the 3-μm region We are using theSpeX instrument on NASArsquos IRTF to measure spectra from ~2 to42 μm So far we have 12 observations of 8 NEAs Of theseobjects three exhibit a 3-μm feature both of our observations of(443) Eros three observations of (1036) Ganymed and (3122)Florence exhibit The NEAs (54789) 2001 MZ7 (96590) 1998 XB(285944) 2001 RZ11 (214088) 2004 JN13 (357439) 2004 BL86do not exhibit a feature Rivkin et al (2013 LPSC) has alsoreported detections of the 3-μm feature on Ganymed and Eros withdata taken in the same year as ours (2012) Band shape albedoand orbital analysis of the NEAs exhibiting the 3-microm featureindicate that the primary production mechanism of OHH O onEros and Ganymed is solar wind interactions For Florence on theother hand it appears that in-fall of carbonaceous material mightbe the primary mechanism We will discuss the implications ofthese results for potential sources of OHH O on the surfaces ofNEAs in general and prospects for future observations

Author(s) Nathanael Wigton Joshua Emery CristinaThomas Andy RivkinInstitution(s) 1 JHUAPL 2 Planetary Science Institute 3University of Tennessee

10607 ndash Euphrosyne As An NEO Source SpectralProperties and Inferences from MeteoritesThe Euphrosyne family is interpreted as ejecta from an impact into31 Euphrosyne a large C-class asteroid in the outer part of themain belt Recent work by Masiero et al suggests that Euphrosynefamily members may preferentially find their way into the NEOpopulation and presumably from there into the meteoritecollections of the worldInterestingly observations of Euphrosyne in the 3-microm spectralregion by Takir et al and Rivkin et al show it to have a roundedband shape and a band center near 31 microm Such a band shape hasnever been seen in any meteorite spectra collected to date butthese characteristics are reminiscent of 24 Themis and 65 Cybelewhose spectra have been interpreted as having bands due to icefrost and organic materials The spectra of Euphrosyne familyobjects and those NEOs thought to have originated in that familytherefore may show how icy objects evolve as they move from theasteroid belt to orbits near 1 AU and how they may (or may not) berepresented in the meteorite record Alternately they may give riseto new interpretations of the absorptions that have not yet beenconsidered

We will discuss the combined implications of Euphrosynersquosspectrum and family dynamics and the opportunities for betterunderstanding the nature of outer belt asteroids that observationsof the Euphrosyne family provide

Author(s) Andrew S Rivkin Lucy F Lim Joshua PEmeryInstitution(s) 1 JHUAPL 2 NASA GSFC 3 University ofTennessee

10608 ndash SOFIA observations of dark asteroidsEvidence for hydrated minerals on asteroidalsurfacesWe present results from recent SOFIA+FORCAST observations ofthree primitive asteroids and compare these to archived SpitzerSpace Telescope (Spitzer) observations of similar objects Threeasteroids from a total of 12 have been observed withSOFIA+FORCAST in our Cycle-3 campaign Currently we haveobserved asteroids 38 Leda 194 Prokne with both G111 and G227grisms and asteroid 266 Aline with G227 Both wavelength regions(G111 85-135-μm and G227 176-277) have recently been shownto contain spectral features directly related degree of alteration ofprimitive meteorites including unaltered CO and CV meteorites(McAdam et al 2015a b) Spectral features in the 176-277-μmregion can be indicative of olivine (195-μm) hydrated minerals(21-μm) and silica glass (22-μm) Spitzer observed eight largeprimitive main-belt asteroids using both low-resolution modes(short-low SL and long-low LL) of the Infrared Spectrograph(IRS) covering 85-38-μm Additionally Spitzer observed 22 darkprimitive asteroids in the 85-135-μm region Asteroids observedwith Spitzer fall into three categories asteroids with a 12-μmfeature of 1-5 depth interpreted as ~60-70 hydrated minerals(McAdam et al 2015a) asteroids with a broader 12-13-μm featurewith strengths ranging from 4-6 with potential features between19-22-μm (where observed) and asteroids with a strong 13-μmfeature (5-10) 15-μm and potentially 19-22-μm features (whereobserved) interpreted as olivine-rich However the uncertaincalibration at the edges of the LL spectral orders complicatesfeature identification 194 Prokne has a feature ~12-13-μm featureand potentially a broad feature between 20-22-μm This isconsistent with primitive asteroids observed with Spitzer that areinterpreted as hydrated mineral-bearing 38 Leda is largelyfeatureless at the noise limit of the spectrum with a potentialfeature at 25-μm unlike asteroids observed by Spitzer 266 Alinehas a weak feature at 225-μm and is potentially similar to thoseasteroids observed with both modes that are hydrated-mineralbearingMcAdam et al (2015a) Icarus 245 320-332McAdam et al (2015b) LPSC abstract 2540

Author(s) Margaret McAdam Jessica M Sunshine MichaelS P T KelleyInstitution(s) 1 University of Maryland

10609 ndash PRIMitive Asteroids Spectroscopic Survey ndashPRIMASS First ResultsNASA OSIRIS-REx and JAXA Hayabusa 2 sample-return missionshave targeted two near-Earth asteroids (101955) Bennu and(162173) 1999 JU3 respectively These are primitive asteroids thatare believed to originate in the inner belt where five distinctsources have been identified four primitive collisional families(Polana Erigone Sulamitis and Clarissa) and a population oflow-albedo and low-inclination background asteroids Identifyingand characterizing the populations from which these two NEAsmight originate will enchance the science return of the twomissionsWith this main objective in mind we initiated in 2010 aspectroscopic survey in the visible and the near-infrared tocharacterize the primitive collisional families in the inner belt andthe low-albedo background population This is the PRIMitiveAsteroids Spectroscopic Survey ndash PRIMASS So far we haveobtained more than 200 spectra using telescopes located atdifferent observatories PRIMASS uses a variety of ground basedfacilities Most of the spectra have been obtained using the 104m

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Gran Telescopio Canarias (GTC) and the 36m TelescopioNazionale Galileo (TNG) both located at the El Roque de losMuchachos Observatory (La Palma Spain) and the 30m NASAInfrared Telescope Facility on Mauna Kea (Hawai USA)We present the first results from our on-going survey (de Leon etal 2015 Pinilla-Alonso et al 2015 Morate et al 2015) focused onthe Polana and the Erigone primitive families with visible andnear-infrared spectra of more than 200 objects most of them withno previous spectroscopic data Our survey is already the largestdatabase of primitive asteroids spectra and we keep obtaining dataon the Sulamitis and the Clarissa families as well as on thebackground low-albedo population

Author(s) Julia de Leon Noemi Pinilla-Alonso HumbertoCampins Vania Lorenzi Javier Licandro David Morate PaoloTanga Alberto Cellino Marco DelboInstitution(s) 1 Fundacion Galileo Galilei - INAF 2 INAFOsservatorio Astrofisico di Torino 3 Instituto de Astrofisica deCanarias 4 Laboratoire Lagrange Observatoire de la Cocircte drsquoAzur5 University of Central Florida Physics Department 6 Universityof Tennessee Department of Earth and Planetary Sciences

10610 ndash 5 ndash 14 μm Spitzer spectra of primitiveasteroid familiesCompositional studies of primitive asteroid families provideconstraints on the physical and chemical environment of the solarnebula and the evolution of the asteroid belt Spectroscopic studiesin the visible and near-infrared have shown spectral diversitybetween primitive families Our goal is to better constrain thecomposition of two primitive families with very different agesThemis (~25 Gyr) and Veritas (~8 Myr) We analyzed 5 ndash 14 μmSpitzer Space Telescope spectra of a total of 18 asteroids nine fromeach family We report the presence of a broad 10-μm emissionfeature attributed to a layer of fine-grained silicates in the spectraof all nine Themis asteroids and six of nine Veritas asteroids in oursample Spectral contrast in statistically significant detections of the10-μm feature ranges from 1 plusmn 01 to 85 plusmn 09 Comparisonwith the spectra of primitive meteorites (McAdam et al 2015Icarus 245 320) suggests asteroids in both families are similar tometeorites with lower abundances of phyllosilicates We used theNear-Earth Asteroid Thermal Model to derive diameters beamingparameters and albedos for our sample Asteroids in both familieshave beaming parameters near unity and geometric albedos in therange 006 plusmn 001 to 014 plusmn 002 We find that contrast of thesilicate emission feature is not correlated with asteroid diameterhowever higher 10-μm contrast may be associated with flatterspectral slopes in the near-infrared The spectra of both familiessuggest icy bodies with some amount of fine-grained silicates butwith coarser grains or denser surface structure than Trojanasteroids and comets

Author(s) Zoe A Landsman Javier Licandro HumbertoCampins Julie Ziffer Maacuterio de PraacuteInstitution(s) 1 Instituto de Astrofiacutesica de Canarias 2Observatoacuterio Nacional 3 University of Central Florida 4University of Southern Maine

10611 ndash Compositional study of the Themis familyThemis is an outer main-belt family comprising more than 4000dynamically well-established members (Nesvorny 2012) mainly B-and C-type asteroids (Florczak et al 1999 Motheacute-Diniz et al 2005Ziffer et al 2011) This family is rather unique for a number ofreasons- It is believed to be the only main-belt family formed from thecatastrophic disruption of a large (Dgt200 km) B-C-type body(Brož et al 2013) As such it offers a unique view on the internalcomposition of a primitive asteroid- Elst-Pizarro one of the family member was one of the first mainbelt comets to be discovered (Hsieh amp Jewitt 2006)- 24 Themis is the first main belt asteroid for which water ice wasdetected at its surface (Campins et al 2010 Rivkin amp Emery 2010)- The low density values recorded for two family members (lt13gcm3 Descamps et al 2007 Marchis et al 2008) likely implyhigh fractions of ice(s) in the interior of these bodies

The last three features all point towards an ice-rich composition forthe Themis parent body while showing little compatibility with athermally metamorphosed body that has been heated throughoutat temperatures exceeding 300 K The latter interpretation waspreviously suggested on the basis of a similarity between thenear-infrared spectral properties of heated CICM chondrites andthose of the family membersrsquo surfaces (Clark et al 2010 Ziffer etal 2011) In brief the Themis family members appear unsampledby our meteorite collections Recently Vernazza et al (2015)instead proposed that Interplanetary Dust Particles (IDPs) may bemore appropriate extraterrestrial analogs for these objectsrsquosurfacesIn the light of Vernazza et al (2015)rsquos recent work we investigatedthe surface mineralogy of a sample of Themis family membersusing a combined dataset of spectra covering the visible (Bus ampBinzel 2002 Lazzaro et al 2004) near-infrared (this work) andmid-infrared (Licandro et al 2012 Hargrove et al 2015) spectralrangesAssuming particle sizes (typically sub- to micrometer sizes) andend-members composition similar to those found in chondriticporous IDPs we modeled the spectral properties of the Themisfamily members The results of this study will be presented indetails

Author(s) Michael Marsset Pierre Vernazza Mirel Birlan Francesca DeMeo Richard P Binzel Christophe Dumas JulienMilli Marcel PopescuInstitution(s) 1 Astronomical Institute of the RomanianAcademy 2 European Southern Observatory 3 Institut deMeacutecanique Ceacuteleste et de Calcul des Epheacutemeacuterides 4 LaboratoiredAstrophysique de Marseille 5 Massachusetts Institute ofTechnology

10612 ndash Interplanetary Dust Particles As Samples ofIcy AsteroidsMeteorites have long been considered as reflections of thecompositional diversity of main belt asteroids and consequentlythey have been used to decipher their origin formation andevolution However while some meteorites are known to samplethe surfaces of metallic rocky and hydrated asteroids (aboutone-third of the mass of the belt) the low-density icy asteroids (C-P- and D-types) representing the rest of the main belt appear tobe unsampled in our meteorite collections Here we provideconclusive evidence that the surface compositions of these icybodies are compatible with those of the most commonextraterrestrial materials (by mass) namely anhydrousinterplanetary dust particles (IDPs) Given that these particles arequite different from known meteorites it follows that thecomposition of the asteroid belt consists largely of more friablematerial not well represented by the cohesive meteorites in ourcollections In the light of our current understanding of the earlydynamical evolution of the solar system meteorites likely samplebodies formed in the inner region of the solar system (05ndash4 AU)whereas chondritic porous IDPs sample bodies that formed in theouter region (gt5 AU)

Author(s) Pierre Vernazza Michael Marsset Pierre Beck Richard Binzel Mirel Birlan Rosario Brunetto FrancescaDeMeo Zahia Djouadi Christophe Dumas Sihane Merouane Olivier Mousis Brigitte ZandaInstitution(s) 1 ESO 2 IAS 3 IMCCE 4 IPAG 5 LaboratoiredAstrophysique de Marseille 6 MIT 7 MNHN 8 MPS

107 ndash Mercury and the Moon10701 ndash Mercuryrsquos exosphere New detectionsdiscoveries and insightsFor over 16 Mercury years the MESSENGER spacecraft orbited theplanet Mercury and conducted a variety of observations of theexosphere Part of the overall observing plan was a search forexospheric species that are less abundant andor more weaklyemitting than the more easily observed Na Ca and Mg For mostof the orbital phase this search has resulted in nothing more than

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2 1

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6 2 1 85 7

19

increasingly refined upper limits However in the last few Mercuryyears three species that had eluded this programmatic search wereobserved Emission from multiple lines of Ca was detectedvalidating the observation of a single line of Ca during the thirdMESSENGER Mercury flyby Multiple lines of Al were alsodetected providing definitive evidence for a species that has beensuggested from ground-based observations Finally emission fromMn has been discovered adding another member to the pantheonof exospheric species All these detections were somewhat localizedabout the planet and during the Mercury year Equally interestingas these observations is absence of detectable emission from otherspecies such as O We will report on both the detections andnon-detections provide altitude profiles where possible anddiscuss the insights gained from these species in the context of theoverall exosphere The NASA MESSENGER Participating ScientistProgram supported this work

Author(s) Ronald J Vervack Jr William E McClintock Rosemary M Killen Aimee W Merkel Matthew H Burger Menelaos Sarantos Timothy A CassidyInstitution(s) 1 GSFC 2 JHUApplied Physics Laboratory 3Morgan State UniversityGESTAR 4 UMBC 5 University ofColorado

10702 ndash A seasonal feature in Mercuryrsquos exospherecaused by meteoroids from comet EnckeThe planet Mercury is enveloped in a tenuous atmosphere theresult of a delicate balance between poorly understood sources andsinks (Killen et al 2007) Meteoroid impacts are a contributingsource process (eg Wurz et al 2010) but their importancecompared to other production mechanisms is uncertainKillen and Hahn (2015) found that seasonal variations inMercurys calcium exosphere as observed by Mercury Atmosphericand Surface Composition Spectrometer (MASCS) onboard theMErcury Surface Space ENvironment GEochemistry andRanging (MESSENGER) spacecraft (Burger et al 2014) may beattributed to impact vaporization of surface material by the infall ofinterplanetary dust However an additional dust source wasrequired to explain a Ca excess at a True Anomaly Angle (TAA) of25plusmn5 deg Killen and Hahn suggested that dust from comet2PEncke crossing Mercurys orbital plane at TAA=45 deg may bethe culpritWe have simulated numerically the stream of meteoroids ejectedfrom Encke in order to identify those particles that impact Mercuryat the present epoch and test the Killen and Hahn conjecture Wefind that Encke particles evolving solely under the gravity of themajor planets and the Sun encounter Mercury at TAA=50-60 degwell after the peak of the Ca excess emission This result isindependent of the time of ejection However the addition ofPoynting-Robertson (P-R) drag in our model couples the age andsize of the meteoroids to the TAA at encounter causing smallerolder particles to encounter Mercury progressively earlier in theHermean year In particular mm-sized grains ejected between 10and 20 kyr ago impact on the nightside hemisphere of Mercury atTAA = 350minus30 deg near the observed peak time of the exosphericfeatureDuring this presentation we will describe our model results anddiscuss their implications for the physical mechanism that injectsimpact-liberated Ca into sunlight as well as the origin and evolutionof the Encke stream of meteoroidsAstronomical Research at Armagh Observatory is funded by theNorthern Ireland Department of Culture Arts and Leisure (DCAL)

Author(s) Apostolos Christou Rosemary M Killen Matthew H BurgerInstitution(s) 1 Armagh Obs 2 Goddard Earth SciencesTechnology and Research Morgan State University 3 NASAGoddard Space Flight Center

10703 ndash Solar Wind Charge Exchange X-ray emissionfrom Mercuryrsquos exosphere Detectability with BepiColomborsquos MIXS spectrometerWe have conducted preliminary hybrid simulations to calculate theSolar Wind Charge Exchange (SWCX) X-ray emission in Mercuryrsquos

exosphere Our results imply that the OVII triplet emissionintensity for standard slow solar wind conditions is of the sameorder as the one predicted by simulations for Mars and measuredby Chandra in past observations of Mars Using an oversimplifieddetector and observation geometry we explore the detectability ofMercurys SWCX emission by the MIXS spectrometer on boardBepi Colomborsquos planetary orbiter (MPO)

Author(s) Dimitra Koutroumpa Konrad Dennerl FranccediloisLeblanc Ronan ModoloInstitution(s) 1 LATMOS-CNRS 2 MPE

10704 ndash Mercuryrsquos EUV Reflectance Spectrum FromMariner 10 RevisitedCarbon as graphite has emerged from recent analyses ofMESSENGER spectrophotometry and theoretical modeling as apossible source for the darkening component in the LowReflectance Material (LRM) pervasive across Mercuryrsquos surfaceMurchie et al (Icarus 254 287 2015) propose graphite inamounts consistent with results from MESSENGERrsquos elementalexperiments for the presence of C as the most likely darkeningcomponent in LRM Vander Kaaden and McCubbin (JGR Planets120 195 2015) report that graphite would be the only buoyantphase in an early magma ocean and any primary flotation crustwould have retained C in the form of graphite AlternativelyGillis-Davis et al (Abstract P1 1A-07 AGU 2013) suggest thatnanophase and microphase iron produced by impacts intoMercuryrsquos crust before and during the late heavy bombardmentcould darken the LRM Carbon in the forms of graphite andanthracite has distinctive far-UV spectral reflectance features TheMESSENGER MASCS UVVS spectrometer does not extend towavelengths short enough to observe these features The Mariner10 EUV airglow spectrometer observed broad swaths of Mercury in10 filters at wavelengths ranging from 304Aring to 1657Aring each having20Aring passbands We now re-analyze these data in a search for thisdistinctive UV signature of graphite across large areas of Mercuryrsquossurface and will report on the results

Author(s) Faith Vilas Amanda R Hendrix Elizabeth AJensenInstitution(s) 1 Planetary Science Institute

10705 ndash Mercuryrsquos gravity field tidal Love number k2and spin axis orientation revealed with MESSENGERradio tracking dataWe are conducting an independent analysis of two-way Dopplerand two-way range radio tracking data from the MESSENGERspacecraft in orbit around Mercury from 2011 to 2015 Our goalsare to estimate Mercuryrsquos gravity field and to obtain independentestimates of the tidal Love number k2 and spin axis orientationOur gravity field solution reproduces existing values with highfidelity and prospects for recovery of the other quantities areexcellentThe tidal Love number k2 provides powerful constraints on interiormodels of Mercury including the mechanical properties of themantle and the possibility of a solid FeS layer at the top of the coreCurrent gravity analyses cannot rule out a wide range of values(k2=43ndash050) and a variety of plausible interior models We areseeking an independent estimate of tidal Love number k2 withimproved errors to further constrain these modelsExisting gravity-based solutions for Mercurys spin axis orientationdiffer from those of Earth-based radar and topography-basedsolutions This difference may indicate an error in one of thedeterminations or a real difference between the orientations aboutwhich the gravity field and the crust rotate which can exist in avariety of plausible configuration Securing an independentestimate of the spin axis orientation is vital because this quantityhas a profound impact on the determination of the moment ofinertia and interior modelsWe have derived a spherical harmonic solution of the gravity fieldto degree and order 40 as well as estimates of the tidal Lovenumber k2 and spin axis orientation

++

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Author(s) Ashok Kumar Verma Jean-Luc MargotInstitution(s) 1 UCLA

10706 ndash Perpetual long libration of terrestrial planetsin tidal resonancesOn the example of Mercury I show that firm planets of terrestrialcomposition locked in the 32 or higher spin-orbit resonancesundergo long-period perpetual libration in longitude without anyinfluence of third bodies This non-damped libration at the naturalfrequency is driven by a secular tidal torque which is increasingwith frequency within a narrow interval around the resonance Thespectrum of regular forced eccentricity-driven libration definesthe conditions for the perpetual long libration The possibility ofvalidating the tidal theory from the observable amplitude ofperpetual libration is discussed

Author(s) Valeri MakarovInstitution(s) 1 US Naval Observatory

10707 ndash The Lunar Profile and Bailys Beads at SolarEclipsesThe lunar mapping from NASAs Lunar Reconaissance Orbiter andJAXAs Kaguya has provided information that allows calculation ofthe lunar limb profile whose low points at total solar eclipsesprovides the Bailys Beads Preparations for the forthcomingAugust 21 2017 total solar eclipse (lunar occultation) whosetotality crosses the continental United States from northwest tosoutheast (httpeclipsesinfo for the International AstronomicalUnion Working Group on Solar Eclipses) has led to newcalculations of the Bailys Beads and of comparisons of the totalityduration between predictions and observations for historicaleventsJMPs research on the annular and total solar eclipses of 2012 wassupported in part by the SolarndashTerrestrial Program of theAtmospheric and Geospace Sciences Division of the NationalScience Foundation through grant AGSndash1047726 His observationsof the 2013 and 2015 total solar eclipses were supported by grants9327-13 and 9616-14 respectively from the Committee forResearch and Exploration of the National Geographic Society withadditional support from Williams College

Author(s) Jay M Pasachoff Ernest T WrightInstitution(s) 1 NASAs GSFC 2 Williams College

10708 ndash Transitional lava flows as potentialanalogues for lunar impact meltsLunar impact melt deposits are among the roughest surfacematerials on the Moon at the decimeter scale even though theyappear smooth at the meter scale These characteristics distinguishthem from well-studied terrestrial analogues such as Hawaiianpāhoehoe and ʻaʻā lava flows The morphology of impact meltdeposits can be related to their emplacement conditions sounderstanding the origin of these unique surface properties willinform us as to the circumstances under which they were formedAlthough there is no perfect archetype for lunar impact melts onEarth certain terrestrial environments lend themselves asfunctional analogues Specifically a variety of transitional lava flowtypes develop if the surface of a pāhoehoe-like flow is disruptedproducing lsquoslabbyrsquo or lsquorubblyrsquo flows that are extremely rough at thedecimeter scale We investigated the surface roughness oftransitional lava flows at Craters of the Moon (COTM) NationalMonument comparing radar imagery and high-resolutiontopographic profiles to similar data sets acquired by the LunarReconnaissance Orbiter for impact melt deposits on the MoonResults suggest that the lava flows at COTM have similar radarproperties to lunar impact melt deposits but the terrestrial flowsare considerably rougher at the meter scale It may be that lunarimpact melts represent a unique lava type not observed on Earthwhose surface texture is influenced by their high emplacementtemperatures andor cooling in a vacuum Information about thesurface properties of lunar impact melt deposits will be critical forfuture landed missions that wish to sample these materials

Author(s) Catherine Neish Scott Hughes ChristopherHamilton Shannon Kobs Nawotniak William Brent Garry John Roma Skok Richard Elphic Lynn Carter JoshuaBandfield Gordon Osinski Darlene Lim Jennifer HeldmannInstitution(s) 1 Idaho State University 2 NASA Ames ResearchCenter 3 NASA GSFC 4 SETI Institute 5 Space Science Institute6 The University of Arizona 7 The University of Western Ontario

10709 ndash The Effect of Pre-Impact Porosity andVertical Density Gradients on the Gravity Signature ofLunar CratersAs a result of NASArsquos dual spacecraft Gravity Recovery And InteriorLaboratory (GRAIL) mission [Zuber et al 2013doi101126science1231507] we now know that the lunar crust ishighly porous and that the porosity varies laterally [Wieczorek etal 2013 doi101126science1231530] and vertically [Besserer etal 2014 doi1010022014GL060240] Analysis of complexcraters located within the lunar highlands reveals that 1) craterslarger than diameter D~210 have positive Bouguer Anomalies(BAs) 2) craters with D ≲ 100 km have both positive and negativeBAs that vary about the (near 0) mean by approximately plusmn 25mGal and 3) D and BA are anticorrelated for craters with D ≲ 100km [Soderblom et al 2015 doi1010022015GL065022]Numerical modeling by Milbury et al [2015 LPSC] shows thatpre-impact porosity is the dominant influence on the gravitysignature of complex craters with D ≲ 100 km and mantle upliftdominates the gravity for those with D gt 140 km Phillips et al[2015 LPSC] showed that complex craters located in the SouthPole-Aitken (SPA) basin tend to have more-negative BAs thansimilar craters in the highlands We use the iSALE hydrocodeincluding pore space compaction [Wuumlnnemann et al 2006doi101016jicarus200510013] and dilatant bulking [Collins2014 doi1010022014JE004708] to understand how the gravitysignature of impact craters develop In this study we vary crustalporosity with depth We find that simulations that have constantporosity with depth have a lower BA for a given crater diameterthan those with the same mean porosity but that vary with depthWe used two different mean porosities (7 and 14) and foundthat the BA increases with increasing porosity similar tosimulations with constant porosity We reproduce the observedanticorrelation between BA and D for D ≲ 100 km only forsimulations where the pre-impact porosity is zero or low Ourresults support the observation that SPA has lower overall porositybut higher vertical gradients giving craters within SPAmore-negative BAs than those within the highlands crust Thesesimulations demonstrate that the BA and porosities reported hereare valid for determining general trends only

Author(s) Colleen Milbury Brandon C Johnson H JayMelosh Gareth S Collins David M Blair Jason MSoderblom Francis Nimmo Roger J Phillips Carver JBierson Maria T ZuberInstitution(s) 1 Imperial College London 2 MassachusettsInstitute of Technology 3 Purdue University 4 SouthwestResearch Institude 5 UC Santa Cruz

10710 ndash Simulated Water Delivery to LunarPermanently Shadowed RegionsA set of Monte Carlo simulations was run to examine waterdiffusion across the lunar surface and specifically to thePermanently Shadowed Regions (PSRs) This work extends theresults of Schorghofer (2014) to latitudes above 5ordm from the poleand to specific PSRs and is accomplished using a separately derivedmodel to independently test Schorghoferrsquos (2014) results Themodel was validated using the results of Schorghofer (2014) at the5ordm latitude line replicating all of the behaviors of that model butwith slightly different values for the total number of tracer particlesarriving and their fractionation25 times fewer particles were able to survive to arrive within 1ordm ofthe pole as compared to those that were able to arrive within 5ordm ofthe pole For the PSRs themselves 187 of particles wereeventually sequestered within the PSRs by the end of oursimulations Examining the amount of water which could betransported over geological time reveals that sufficient water moves

1 1

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via migration to (1) supply the hydrogen signals observed by LEND(Mitrofanov et al 2012) (2) the frost at Haworth Crater(Gladstone et al 2012) as well as to explain (3) the high level ofwater seen in the soils of Cabeus Crater in the LCROSS experiment(Colaprete et al 2010) without the need to invoke another watersupply mechanismIn all cases the average time required for migration was small withaverage arrival times of less than a lunar day following an impactSubstantial differences were observed in the amount of wateraccreted by the different PSRs with Cabeus Crater accreting by farthe most water per square meter Faustini and the HaworthLowlands have the next highest delivery receiving ~60 each asmuch water as Cabeus per square meter Shackleton has the lowestwater delivery receiving only ~5 as much water per square meteras Cabeus The simulated results show a clear latitudinal trend withmore water emplaced at lower latitudes Yet the data show verylittle difference between the PSRs in terms of the amount offractionation taking place and low levels of fractionation overallconsidering 1001 distillation between the impactor and the PSRs

Author(s) John MooresInstitution(s) 1 York University

10711 ndash The Influence of Surface Roughness onVolatile Transport on the MoonThe Moon and other virtually airless bodies provide distinctiveenvironments for the transport and sequestration of water andother volatiles delivered to their surfaces by various sources Herewe conduct numerical simulations to investigate the delivery ofwater to the Moon through comet impacts focusing on the role ofsmall-scale topography (ie surface roughness unresolved byorbital measurements) in the migration and cold-trapping ofimpact-delivered water The simulated comet impact generates atransient collisonally thick water vapor atmosphere that surroundsthe Moon for at least several lunar days During this time somewater is captured by permanently shadowed craters (cold traps)near the lunar poles where temperatures are sufficiently low thatvolatiles can remain sequestered over geological time scalesSurface temperature is a critical parameter that determines theresidence time of a migrating water molecule on the lunar surfacethereby affecting the rapidity of volatile transport though pressure-driven winds the susceptibility of migrating molecules to photo-destruction and the large-scale structure of the impact-generatedatmosphere - all of which ultimately affect the rate and magnitudeof cold-trapping The roughness of the lunar surface at smallscales the insulating nature of the lunar regolith and the absenceof strong convective heat transport lead to sharp surfacetemperature gradients surfaces separated by only a fewmillimeters can have dramatically different temperaturesSignificantly small-scale roughness gives rise to cold temporaryand permanent shadows that may affect the rate at which watermigrates to permanent cold traps near the lunar poles and to thetemporary shelter of the cold lunar night side Here we develop asurface roughnesstemperature model consistent with observedbolometric brightness temperature at larger scales suitable forsimulations of volatile transport on a global scale We will present acomparison of results from impact-generated atmospheresimulations with and without the surface roughness model in orderto understand how small-scale roughness influences transientdeposition patterns and the rate and magnitude of cold trapcapture

Author(s) Parvathy Prem Natalia A Artemieva David BGoldstein Philip L Varghese Laurence M TraftonInstitution(s) 1 Planetary Science Institute 2 The University ofTexas at Austin

10712 ndash LRO-LAMP Observations of Lunar ExosphericHeliumWe present results from Lunar Reconnaissance Orbiterrsquos (LRO)UV spectrograph LAMP (Lyman-Alpha Mapping Project) campaignto study the lunar atmosphere Two kinds of off-nadir maneuvers(lateral rolls and pitches towards and opposite the direction ofmotion of LRO) were performed to search for resonantly scattering

species increasing the illuminated line-of-sight (and hence thesignal from atoms resonantly scattering the solar photons)compared to previously reported LAMP ldquotwilight observationsrdquo[Cook amp Stern 2014] Helium was the only elementdistinguishable on a daily basis and we present latitudinal profilesof its line-of-sight column density in December 2013 Wecompared the helium line-of-sight column densities with solarwind alpha particle fluxes measured from the ARTEMIS(Acceleration Reconnection Turbulence amp Electrodynamics ofMoonrsquos Interaction with the Sun) twin spacecraft Our data show acorrelation with the solar wind alpha particle flux confirming thatthe solar wind is the main source of the lunar helium but not witha 11 relationship Assuming that the lunar soil is saturated withhelium atoms our results suggest that not all of the incident alphaparticles are converted to thermalized helium allowing for anon-negligible fraction (~50 ) to escape as suprathermal heliumor simply backscattered from the lunar surface We also supportthe finding by Benna et al [2015] and Hurley et al [2015] that anon-zero contribution from endogenic helium coming fromradioactive decay of Th and U within the mantle is presentand is estimated to be (45plusmn12) x 10 He atoms cm s Finallywe compare LAMP-derived helium surface density with the onerecorded by the mass spectrometer LACE (Lunar AtmosphericComposition Experiment) deployed on the lunar surface during theApollo 17 mission finding good agreement between the twomeasurements These LRO off-nadir maneuvers allow LAMP toprovide unique coverage of local solar time and latitude of the lunarexospheric helium allowing for a better understanding of thetemporal and spatial structure of the lunar exosphere

Author(s) Cesare Grava Kurt D Retherford Dana MHurley Paul D Feldman Randy Gladstone Thomas KGreathouse Jason C Cook Alan Stern Wayne R Pryor Jasper S Halekas David E KaufmannInstitution(s) 1 Central Arizona College 2 Johns HopkinsUniversity 3 Johns Hopkins University - Applied PhysicsLaboratory 4 Southwest Research Institute 5 University of Iowa

200 ndash Pluto System IV--Saving the Best forLast20001 ndash Configuration of Plutos Volatile IcesWe report on near-infrared remote sensing by New HorizonsRalph instrument (Reuter et al 2008 Space Sci Rev 140129-154) of Plutos N CO and CH ices These especially volatileices are mobile even at Plutos cryogenic surface temperaturesSunlight reflected from these ices becomes imprinted with theircharacteristic spectral absorption bands The detailed appearanceof these absorption features depends on many aspects of localcomposition thermodynamic state and texture Multiple-scattering radiative transfer models are used to retrievequantitative information about these properties and to map howthey vary across Plutos surface Using parameter maps derivedfrom New Horizons observations we investigate the strikingregional differences in the abundances and scattering properties ofPlutos volatile ices Comparing these spatial patterns with theunderlying geology provides valuable constraints on processesactively modifying the planets surface over a variety of spatialscales ranging from global latitudinal patterns to more regional andlocal processes within and around the feature informally known asSputnik Planum This work was supported by the NASA NewHorizons Project

1

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232 2386 -2 -1

4 43 2 4

4 4 4 15 4

2 4

22

Author(s) William M Grundy R P Binzel J C Cook D PCruikshank C M Dalle Ore A M Earle K Ennico D EJennings C JA Howett I R Linscott A W Lunsford C BOlkin A H Parker J Wm Parker S Protopapa D C Reuter KN Singer J R Spencer S A Stern C CC Tsang A JVerbiscer H A Weaver L A Young K Berry M W Buie J AStansberryInstitution(s) 1 Johns Hopkins University Applied PhysicsLaboratory 2 Lowell Obs 3 Massachusetts Institute ofTechnology 4 NASA Ames Research Center 5 NASA GoddardSpace Flight Center 6 Southwest Research Institute 7 SpaceTelescope Science Institute 8 Stanford University 9 University ofMaryland 10 University of Virginia 11 USGS Astrogeology

20002 ndash The Search for Pluto WaterOn July 14 2015 the New Horizons spacecraft made its closestapproach to Pluto at about ~12000 km from Plutos surface TheLEISA (Linear Etalon Imaging Spectral Array) component of theRalph instrument (Reuter DC Stern SA Scherrer J et al2008 Space Sci Rev 140 129) obtained spatially resolved nearinfrared spectra at scales as small as 3 kmpix LEISA covers thewavelength range 125 to 25 μm at a spectral resolution (λΔλ) of240 and the 21 to 225 μm range at a resolution of 560 Theobservations from this instrument are being used to map thedistribution of Plutos known ices such as N CH CO and C Has well as search for H O-ice To date H O-ice has evadeddetection from Earth bound observatories Observations based onLORRI the LOng Range Reconnaissance Imager suggest H O-iceis a major component of several mountain ranges around thewestern perimeter of the landmass informally named TombaughRegio If true H O-ice may be found in small isolated regionsaround Pluto We will present our analysis of all LESIA data ofPluto in hand to search for and understand the distribution ofH O-ice If found we will also discuss limits on crystalline vsamorphous H O-ice and temperature measurements based on the165 microm crystalline H O-ice feature This work was supported byNASAs New Horizons project

Author(s) Jason C Cook Dale P Cruikshank Cristina MDalle Ore Kimberly Ennico William M Grundy Cathy BOlkin Silvia Protopapa S Alan Stern Harold A Weaver Leslie A YoungInstitution(s) 1 John Hopkins University Applied PhysicsLaboratory 2 Lowell Observatory 3 NASA Ames ResearchCenter 4 SETI Institute 5 Southwest Research Institute 6University of Maryland

20003 ndash New Horizons data in the context of priorobservationsThe New Horizons encounter data have revealed a diverse andcomplicated surface and atmosphere for Pluto showing strongcorrelations between geologic features and the albedo andcompositional units known from ground- and HST-basedobservations over the decades prior This presentation makedetailed comparisons between the long time base and low spatialresolution data and the new high resolution stanpshot of Plutofrom the flyby Special emphasis will be placed on the albedoevolution over time with some attention paid to near-infraredspectral signatures We will compare the albedo maps from mutualevent data and two epochs of HST observations against the NewHorizons images after correcting for viewing geometry Alsoincluded will be a discussion of the evolutionary trends in thehemispherically averaged spectral properties from LowellObservatory and IRTF data against the resolved compositional andspectral maps from New Horizons The combination of these datasets now permits an unprecedented ability to constraintime-variability on the surface from apparent changes due toviewing geometry and surface inhomogeneities This work requiresa reconcilliation of surface scattering properties that are enabled bythe firm determination of the size of Pluto and this will bediscussed as well This work was supported by the NASA NewHorizons project

Author(s) Marc W Buie S Alan Stern Leslie A Young Harold A Weaver Catherine B Olkin Kimberly Ennico JeffreyM Moore William M GrundyInstitution(s) 1 JHUApplied Physics Laboratory 2 LowellObservatory 3 NASA Ames Research Center 4 SouthwestResearch Institute

20004 ndash Migration of Frosts from High-AlbedoRegions of Pluto what New Horizons RevealsWith its high eccentricity and obliquity Pluto should exhibitseasonal volatile transport on its surface Several lines of evidencesupport this transport doubling of Plutorsquos atmospheric pressureover the past two decades (Young et al 2013 Ap J 766 L22Olkin et al 2015 Icarus 246 230) changes in its historicalrotational light curve once all variations due to viewing geometryhave been modelled (Buratti et al 2015 Ap J 804 L6) andchanges in HST albedo maps (Buie et al 2010 Astron J 1391128) New Horizons LORRI images reveal that the region ofgreatest albedo change is not the polar cap(s) of Pluto but thefeature informally named Tombaugh Regio (TR) This feature hasa normal reflectance as high as ~08 in some places and it issuperposed on older lower-albedo pre-existing terrain with analbedo of only ~010 This contrast is larger than any other body inthe Solar System except for Iapetus This albedo dichotomy leadsto a complicated system of cold-trapping and thermal segregationbeyond the simple picture of seasonal volatile transport Whateverthe origin of TR it initially acted as a cold trap as the temperaturedifferential between the high and low albedo regions could beenormous possibly approaching 20K based on their albedodifferences and assuming their normalized phase curves aresimilar This latter assumption will be refined as the full NewHorizons data set is returnedOver six decades of ground-based photometry suggest that TR hasbeen decreasing in albedo over the last 25 years Possible causesinclude changing insolation angles or sublimation from the edgeswhere the high-albedo material impinges on a much warmersubstrateFunding by the NASA New Horizons Project acknowledged

Author(s) Bonnie J Buratti S A Stern Hal A Weaver Leslie A Young Cathy B Olkin Kimberly Ennico Richard PBinzel Amanda Zangari Alissa M EarleInstitution(s) 1 JHU Applied Physics Lab 2 JPL 3 MIT 4NASA Ames 5 SWRI

20005 ndash Correlating Plutos Albedo Distribution toLong Term Insolation PatternsNASAs New Horizons reconnaissance of the Pluto system hasrevealed striking albedo contrasts from polar to equatorial latitudeson Pluto as well as sharp boundaries for longitudinal variationsThese contrasts suggest Pluto undergoes dynamic evolution thatdrives the redistribution of volatiles Using the New Horizonsresults as a template in this talk we will explore the volatilemigration process driven seasonally on Pluto considering multipletimescales These timescales include the current orbit (248 years)as well as the timescales for obliquity precession (amplitude of 23degrees over 3 Myrs) and regression of the orbital longitude ofperihelion (37 Myrs) We will build upon the long-term insolationhistory model described by Earle and Binzel (2015 Icarus 250405-412) with the goal of identifying the most critical timescalesthat drive the features observed in Plutorsquos current post-perihelionepoch This work was supported by the NASA New HorizonsProject

Author(s) Alissa M Earle Richard P Binzel S AlanStern Leslie A Young Bonnie J Buratti Kimberly Ennico Will M Grundy Catherine B Olkin John R Spencer Hal AWeaverInstitution(s) 1 Jet Propulsion Laboratory 2 Johns HopkinsUniversity Applied Physics Lab 3 Lowell Observatory 4Massachusetts Institute of Technology 5 NASA Ames ResearchCenter 6 Southwest Research Institute

20006 ndash A Large Impact Origin for Sputnik Planum

2 3 64 4 3 4

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6 6 6 610 1 6 11 6

7

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22

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5 34 3 2

5 6 5 15

4 4 41 4 3

3 2

2 5 15 5 4

3 5 3

4 46 6 1 5

3 6 62

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and Surrounding Terrains PlutoOne of the most prominent features on Pluto discovered by NewHorizons is the oval-shaped bright deposit within westernTombaugh Regio (all names used herein are informal) Thissmooth bright deposit provisionally identified with frozen nitrogenand methane and informally referred to as Sputnik Planum isbounded on the northeast by an arcuate scarp (Cousteau Rupes)The smooth bright material there embays what appears to be aneroded plateau 1-2 km high The arcuate scarp leads to speculationthat the deposits formed in an ancient impact basin but detailedmapping at 2 km pixel scales suggests that this large structure ismore complex than any simple impact basin To the southwest area series of high peaks and massifs (also embayed by brightmaterial) but these broken massifs have a different morphologyfrom Cousteau Rupes being both higher and more disrupted Thesouthern section of this putative 800-km-wide circular structure iscompletely missing as smooth material extends well to the south ofthe nominal rim location A possible analog occurs at the ldquootherEnd of the Solar Systemrdquo on Mercury in Caloris Basin This1400-km-wide impact basin is also irregular in shape with largedeviations form circularity and occasional large massifs alongsome rim segments Post-impact smooth plains embay the rimscarp in some areas though these are likely to be volcanic plains onMercury The relief of the rim scarps to the NE and SW andputative evidence for convection within Sputnik Planum suggeststhat the floor of the deposits lies 1-3 km below the mean surface(pending stereo mapping) This depth is consistent with the fillingof an ancient impact basin with ices deposited either volcanicallyor atmospherically although other explanations are also possibleThis work was supported by NASAs New Horizons project

Author(s) Paul M Schenk William McKinnon JeffreyMoore Francis Nimmo S Alan Stern Hal Weaver KimberlyEnnico Cathy Olkin Leslie YoungInstitution(s) 1 Applied Physics Lab 2 Lunar and PlanetaryInst 3 NASA Ames Res Ctr 4 Southwest Research Institute 5UC Santa Cruz 6 Washington University

20007 ndash The Icy Cold Heart of PlutoThe locations of large deposits of frozen volatiles on planetarysurfaces are largely coincident with areas receiving the minimumannual influx of solar energy familiar examples include the polarcaps of Earth and Mars For planets tilted by more than 45 degreeshowever the poles actually receive more energy than some otherlatitudes Pluto with its current obliquity of 119 degrees hasminima in its average annual insolation at +- 27 degrees latitudewith ~15 more energy flux going to the equator and ~15 moreto the poles Remarkably the fraction of annual solar energyincident on different latitudes depends only on the obliquity of theplanet and not on any of its orbital parametersOver millions of years Plutos obliquity varies sinusoidally from102-126 degrees significantly affecting the latitudinal profile ofsolar energy deposition Roughly 1Myr ago the poles received 15more energy that today while the equator received 13 less Theenergy flux to latitudes between 25-35 degrees is far more stableremaining low over the presumably billions of years since Plutoacquired its current spin properties Like the poles at Earth thesemid latitudes on Pluto should be favored for the long-termdeposition of volatile ices This is indeed the location of the brighticy heart of Pluto Sputnik PlanumReflected light and emitted thermal radiation from Charonincreases annual insolation to one side of Pluto by of order 002Although small the bulk of the energy is delivered at night toPlutos cold equatorial regions Furthermore Charons thermalinfrared radiation is easily absorbed by icy deposits on Plutoslowing deposition and facilitating sublimation of volatiles Weargue that the slight but persistent preference for ices to form andsurvive in the anti-Charon Plutos heart

Author(s) Douglas P HamiltonInstitution(s) 1 Univ of Maryland

20008 ndash Pluto and Charon Color Light Curves fromNew Horizons on Approach

On approach to the Pluto system New Horizonsrsquo RalphInstrumentrsquos Multicolor Visible Imaging Camera (MVIC) observedPluto and Charon spatially separated between April 9 and June23 2015 In this period Pluto and Charon were observed totransition from unresolved objects to resolved and their integrateddisk intensities were measured in four MVIC filters blue (400-550nm) red (540-700 nm) near-infrared (780ndash975 nm) andmethane (860ndash910 nm) The measurement suite sampled thebodies over all longitudes We will present the color rotational lightcurves for Pluto and Charon and compare them to previous (BuieM et al 2010 AJ 139 1117 Buratti BJ et al 2015 ApJ 804 L6) andconcurrent ground-based BVR monitoring We will also comparethese data to color images of the encounter hemisphere takenduring New Horizonsrsquo July 14 2015 Pluto and Charon flyby as thisdata set provides a unique bridge between Pluto amp Charon asviewed as astronomical targets versus the complex worlds that earlydata from New Horizons has revealed them to be This work wassupported by NASArsquos New Horizons project

Author(s) Kimberly Ennico C JA Howett C B Olkin D C Reuter B J Buratti M W Buie W M Grundy A HParker A M Zangari R P Binzel J C Cook D PCruikshank C M Dalle Ore A M Earle D E Jennings I RLinscott J Wm Parker S Protopapa K N Singer J RSpencer S A Stern C CC Tsang A J Verbiscer H AWeaver L A YoungInstitution(s) 1 Jet Propulsion Laboratory 2 Johns HopkinsUniversity Applied Physics Laboratory 3 Lowell Observatory 4Massachusetts Institute of Technology 5 NASA Ames ResearchCenter 6 NASA Goddard Space Flight Center 7 SETI Institute 8Southwest Research Institute 9 Stanford University 10University of Maryland 11 University of Virginia

20009D ndash Plutos atmosphere from stellaroccultations in 2012 and 2013We present results from two Pluto stellar occultations observed on18 July 2012 and 04 May 2013 and monitored respectively fromfive and six sites in South America Both campaigns involved largetelescopes (including the 82-m VLT at ESOParanal) The highSNR ratios and multi-chord coverage provide amoung the bestPluto atmospheric profiles ever obtained from the groundWe show that a spherically symmetric clear (no-haze) and pure N2atmosphere with a unique temperature profile satisfactorily fits thetwelve lightcurves provided by the two events We find however asmall but significant increase of pressure of 6 (6-sigma level)between the two dates with values of 216 plusmn 02 and 230 plusmn 001μbar at the reference radius 1275 km respectivelyWe provide atmospheric constrains between 1190 km and 1450 kmfrom Plutos center and we determine the temperature profile withaccuracy of a few km in vertical scale Our model shows astratosphere with strong positive gradient between 1190 km (at 36K 11 μbar) and r =1215 km (60 μbar) where a temperaturemaximum of 110 K is reached Above it is a mesosphere withnegative thermal gradient of -02 Kkm up to 1390 km (025 μbar)at which point the mesosphere connects itself to a moreisothermal upper branch at 81 K This profile provides (assumingno troposphere) a Pluto surface radius of 1190 plusmn 5 km consistentwith preliminary values obtained by New Horizons Currentlymeasured CO abundances are too low to explain the negativemesospheric thermal gradient We explore the possibility of anHCN (recently detected by ALMA) cooling This model howeverrequires largely supersaturated HCN Zonal winds and verticalcompositional variations of the atmosphere are also unable toexplain the observed mesospheric trendThese events are the last useful ground-based occultationsrecorded before the 29 June 2015 occultation observed fromAustralia and New Zealand and before the NASAs New Horizonsflyby of July 2015 This work can serve as a benchmark in the NewHorizons context enabling comparisons between ground-basedand space results concerning Plutos atmospheric structure andtemporal evolution

2 63 5 4 13 4 4

1

5 8 86 1 8 3

8 8 4 85 7 4 6

9 8 10 88 8 8 112 8

24

Author(s) Alex Dias-Oliveira Bruno Sicardy EmmanuelLellouch Roberto Vieira-Martins Marcelo Assafin JuacutelioIgnaacutecio Bueno Camargo Felipe Braga-Ribas Altair Gomes-Juacutenior Gustavo Bendetti-Rossi Franccedilois Colas AliceDecock Alain Doressoundiram Christophe Dumas MarceloEmiacutelio Joaquin Fabrega Polleri Ricardo Gil-Hutton MichaelGillon Julien Girard George Hau Valentin Ivanov Emmanuel Jehin Jean Lecacheux Rodrigo Leiva CeciacuteliaLopez-Sisterna Luigi Mancini Jean Manfroid AlainMaury Erick Meza Nicolas Morales Leslie Nagy CyrielleOpitom Joseacute Luiz Ortiz Joe Pollock Franccediloise Roques Colin Snodgrass Jean Franccedilois Soulier Audrey Thirouin Leonardo Vanzi Thomas Widemann Daniel Reichart AaronLaCluyze Joshua B Haislip Kevin Ivarsen MartinDominik Uffe Joslashrgensen Jesper SkottfeltInstitution(s) 1 Appalachian State University 2 AssociationDes Etoiles pour Tous 3 CASLEO-CONICET 4 ESO 5 ESO 6Instituto de Astrofiacutesica de Andaluciacutea 7 Lowell Observatory 8Max Planck Institute for Astronomy 9 Observatoire deParisIMCCE 10 Observatoire de ParisLESIA 11 Observatoacuteriodo ValongoUFRJ 12 Observatoacuterio Nacional 13 ObservatoacuterioPanemntildeo 14 PUC 15 SPACE 16 The Open University 17UEPG 18 Universidade Nacional de San Juan 19 Universiteacute deLiege 20 University of Copenhagen 21 University of NorthCarolina 22 University of St Andrews 23 UTFPR

201 ndash sup3Venus Asteroid Dynamics20101D ndash The effect of solar flares coronal massejections and co-rotating interaction regions on theVenusian 5577 nm oxygen green lineThe Venusian 5577nm OI (1S - 1D) (oxygen green line) nightglowemission is known to be highly temporally variable The reason forthis variability is unknown We propose that the emission is due toelectron precipitation from intense solar storms For mydissertation I observed the Venusian green line after solar flarescoronal mass ejections (CMEs) and co-rotating interaction regionsfrom December 2010 to April 2015 using the high resolutionAstrophysical Research Consortium Echelle Spectrograph on theApache Point Observatory 35-m telescope Combining theseobservation with all other published observations we find that thestrongest detections occur after CME impacts and we concludeelectron precipitation is required to produce green line emissionWe do not detect emission from the 6300nm OI (1D - 3P) oxygenred line for any observationIn an effort to determine the emitting altitude therebyconstraining the possible emission processes responsible for greenline emission and quantify the electron energy and flux enteringthe Venusian nightside we conducted analyses of space-basedobservations of the Venusian nightglow and ionosphere collectedby the Venus Express (VEX) spacecraft We were unable to detectthe green line but confirmed that electron energy and fluxincreases after CME impactsIn order to determine the effect of storm condition electronprecipitation on the Venusian green line we modeled the Venusianionosphere using the TRANSCAR model (a 1-Dmagnetohydrodynamic ionospheric model that simulates auroralemission from electron precipitation) by applying observedelectron energies and fluxes We found that electron energy plays aprimary role in producing increased green line emission in theVenusian ionosphereBased on observation and modeling results we conclude that theVenusian green line is an auroral-type emission that occurs aftersolar storms with the largest intensities observed after CMEsPost-CME electron fluxes and energies are sufficient to producethe observed green line intensity with the lack of red line emissionWe find that O + e is the greatest contributor to the OI (1S) stateand is responsible for the observed green line emission

Author(s) Candace L Gray Nancy Chanover TomSlanger Karan Molaverdikhani Kerstin Peter Bernd Haumlusler Silvia Tellmann Martin Paumltzold Olivier Witasse Pierre-LouisBlelly Glyn CollinsonInstitution(s) 1 European Space Research and TechnologyCentre 2 Institut de Recherche en Astrophysique et Planeacutetologie 3 Laboratory for Atmospheric and Space Physics 4 NASAGoddard Space Flight Center 5 New Mexico State University 6SRI International 7 Universitaumlt der Bundeswehr Muumlnchen 8University of Koln

20102 ndash Variability of the Venus condensationalclouds from analysis of VIRTIS-M-IR observations ofthe near-infrared spectral windowsThe Medium Resolution Infrared wavelength channel of theVisible and Infrared Thermal Imaging Spectrometer(VIRTIS-M-IR) on the Venus Express spacecraft observed theatmosphere and surface of Venus for 921 orbits following orbitinsertion in April 2006 until the failure of the cooling unit inOctober 2008 The clouds of Venus were long thought to be auniform sort of perpetual stratocumulus but near infraredobservations by fly-by spacecraft such as Galileo (Near InfraredMapping Spectrometer) and Cassini (Visible and Infrared MappingSpectrometer) as well as ground-based observations indicated agreat deal of temporal and spatial inhomogeneity The nearlythree-year lifetime of the VIRTIS-M-IR instrument on VenusExpress presents an unprecedented opportunity to quantify thesespatial and temporal variations of the Venus clouds Here wepresent the results of an initial quantification of the overalltendencies of the Venus clouds as measured by variations in thenear infrared spectral windows located between wavelengths of 10microm and 26 microm In a companion submission we also investigatethe variations of carbon monoxide and other trace speciesquantifiable in these data (Tsang and McGouldrick 2015) Thiswork is supported by the Planetary Mission Data Analysis ProgramGrant Number NNX14AP94G

Author(s) Kevin McGouldrick Constantine C C TsangInstitution(s) 1 Southwest Research Institute 2 University ofColorado

20103 ndash Thermal structure and minor speciesdistribution of Venus mesosphere by ALMA submmobservationsVenus upper atmosphere (70ndash150 km altitude) is a transitionregion characterized by a complex dynamics strong retrogradezonal winds dominate the lower mesosphere while a solar-to-antisolar circulation is observed in the upper mesospherelowerthermosphere In addition photochemical processes play animportant role at these altitudes and affect the thermal structureand chemical stability of the entire atmosphere Sulfur dioxide andwater vapor are key species in the photochemical cycles takingplace in the troposphere and mesosphere of Venus They arecarried by convective transport together with the Hadleycirculation up to about 60 km where SO is photodissociated andoxydated leading to the formation of H SO which condenses inthe clouds enshrouding the planet Previous observations obtainedby several instruments on board Venus Express and duringground-based campaigns have shown evidence of strong temporalvariations both on day-to-day as well as longer timescales ofdensity temperature and SO abundance Such strong variability isstill not well understoodSubmillimeter observations obtained with the Atacama LargeMillimeter Array (ALMA) offer the possibility of probing Venusupper mesosphere and of monitoring minor species winds and thethermal structure A first set of observations was obtained onNovember 14 15 26 and 27 2011 during the first ALMA EarlyScience observation cycle These observations targeted SO SOHDO and CO transitions around 345 GHz during four sequences of30 minutes each The Venusrsquo disk was about 11rdquo with anillumination factor of 90 so that mostly the dayside of the planetwas mappedAssuming nominal night-time and dayside CO abundance profilesfrom Clancy et al 2013 we retrieved vertical temperature profiles

12 1010 12 11

12 2311 12 910 10 5

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2

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over the entire disk as a function of latitude and local time for thefour days of observation Temperature profiles were later used toderive the abundances of minor species (HDO SO SO ) in eachpixel of the disk in order to study their spatial and temporalvariability

Author(s) Arianna Piccialli Raphael Moreno ThereseEncrenaz Thierry Fouchet Emmanuel Lellouch ArielleMoullet Thomas WidemannInstitution(s) 1 LESIA Observatoire de Paris 2 NationalRadio Astronomy Observatory (NRAO)

20104 ndash Observations of Altitude Dependence andTemporal Variation of ClO in the Venus MesosphereAnalysis of the first observations of ClO in the Venus mesosphereindicate ClO is present above 85 +-3 km altitude and not belowThe retrieved nightside mean abundances show a factor of 2decrease between observation dates Oct 23 and Nov 11 2015 withchange between the two dates evident at more than two sigmaconfidence Abundances and altitude distributions are retrievedfrom submm spectroscopic observations of the 35288 GHz line of

ClO (made with the James Clerk Maxwell Telescope - JCMT -located an Mauna Kea Hawaii)Detection of ClO in the Venus atmosphere confirms a theory putforward by Yung and DeMore (1982) that the Venus atmosphere isstabilized as CO due to chlorine catalytic recombination of CO andO (Without some form of catalysis the Venus atmosphere wouldhave 10s of percent CO and O but it is in fact 97 CO and 3N with only trace amounts of CO and O ) Detailed retrieval ofClO abundances and altitude distributions (the focus of this talk)provides greater insight to the catalytic process and to otheraspects of Venus atmospheric chlorine chemistry We comparefindings of our quantitave retrieval with predictions ofphotochemical models and discuss the implications for chlorinephotochemisty of the Venus atmosphere We also discuss retrievedClO temporal variation with that of upper mesospheric HCl(Sandor and Clancy 2012)[We acknowledge funding of this project by NASA grantsNNX10AB33G NNX12AI32G and NNX14AK05G as well as NSFgrant AST-1312985]

Author(s) Brad J Sandor R Todd ClancyInstitution(s) 1 Space Science Institute

20105 ndash A refined orbit for the satellite of asteroid(107) CamillaThe satellite of the Cybele asteroid (107) Camilla was discovered inMarch 2001 using the Hubble Space Telescope (Storrs et al 2001IAUC 7599) From a set of 23 positions derived from adaptiveoptics observations obtained over three years with the ESO VLTKeck-II and Gemini-North telescopes Marchis et al (2008 Icarus196) determined its orbit to be nearly circularIn the new work reported here we compiled reduced and analyzedobservations at 39 epochs (including the 23 positions previouslyanalyzed) by adding additional observations taken from dataarchives HST in 2001 Keck in 2002 2003 and 2009 Gemini in2010 and VLT in 2011 The present dataset hence contains twice asmany epochs as the prior analysis and covers a time span that isthree times longer (more than a decade)We use our orbit determination algorithm Genoid (GENetic OrbitIDentification) a genetic based algorithm that relies on ametaheuristic method and a dynamical model of the Solar System(Vachier et al 2012 AampA 543) The method uses two models asimple Keplerian model to minimize the search-time for an orbitalsolution exploring a wide space of solutions and a full N-bodyproblem that includes the gravitational field of the primary asteroidup to 4th orderThe orbit we derive fits all 39 observed positions of the satellitewith an RMS residual of only milli-arcseconds which correspondsto sub-pixel accuracy We found the orbit of the satellite to becircular and roughly aligned with the equatorial plane of CamillaThe refined mass of the system is (12 plusmn 1) x 10^18 kg for an orbitalperiod of 371 daysWe will present this improved orbital solution of the satellite of

Camilla as well as predictions for upcoming stellar occultationevents

Author(s) Myriam Virginia Pajuelo Benoit Carry Frederic Vachier Jerome Berthier Pascal Descamp William JMerline Peter M Tamblyn Al Conrad Alex Storrs Jean-LucMargot Frank Marchis Pierre Kervella Julien H GirardInstitution(s) 1 ESO 2 IMCCE Observatoire de Paris 3 LargeBinocular Telescope Observatory 4 LESIA Observatoire de Paris5 SETI Institute 6 Southwest Research Institute 7 TowsonUniversity 8 UCLA

20106 ndash On the oldest asteroid families in the mainbeltAsteroid families are group of minor bodies produced by collisionsOnce the parent body is disrupted by a collision and fragments arelaunched into space their orbits evolve because of severalgravitational and non-gravitational effects such as diffusion inmean-motion resonances Yarkovsky and YORP effects collisionalevolution etc The subsequent dynamical evolution of asteroidfamily members may cause some of the original fragments to travelbeyond the recognizable limits of the asteroid family Eventuallythe whole family will dynamically disperse and no longer berecognizable Dynamical erosion of asteroid families has been thesubject of a few recent studies mostly focused on smaller asteroidgroupsA natural question that may arise concerns the timescales fordispersion of large families In particular what is the oldest stillrecognizable family in the main belt Are there any families thatmay date from the late stages of the Late Heavy Bombardment andthat could provide clues on our understanding of the primitiveSolar System In this work we investigate the dynamical stability ofseven of the allegedly oldest families in the asteroid main beltwhen resonant dynamics Yarkovsky and stochastic YORP effectsand past changes in the solar luminosity are considered None ofthe studied families is estimated to be older than 30 Gyr Resultsof our numerical simulations show that some of the members ofthe largest families studied could have survived since 42 Gyr butwith a significant depletion in the number of the smallest (D lt 5km) family members

Author(s) Valerio Carruba David Nesvornyacute SafwanAljbaae Rita C DomingosInstitution(s) 1 SouthWest Research Institute 2 UNESP

20107 ndash Asteroid Impacts Crater Scaling Laws and aProposed Younger Age for Venuss SurfaceA fascinating on-going debate concerns the asteroid sizes needed toform certain large craters For example numerical hydrocodemodels predict that ~12-14 km and ~8 km diameter asteroids areneeded to produce craters like Chicxulub (~180 km) and Popigai(~100 km) respectively The abundance of extraterrestrial IrOsmeasured at well-characterized impact boundaries on land and inoceanic cores however predict far smaller projectiles 4-6 km and25-4 km respectively (eg Paquay et al 2014 F Kyte perscomm) To test who might be right by proxy we transformed thenear-Earth object (NEO) size distribution (Harris amp DAbramo2015) where gt 90 of the D gt 1 km asteroids are known into amodel crater size distribution and compared it to the distribution ofD gt 20 km craters formed on the Moon Mars and Venus over thelast ~1-3 Gyr Here we kept things simple and assumed that fdescribed the ratio between all crater and asteroid diameters ofinterest (ie f = D_crater D_proj)To our surprise we found f ~ 23-26 produced excellent matches forthe crater size distributions on the Moon Mars and Venus despitetheir differences in gravity surface properties impact velocitiesetc These same values work well for the Earth as well Considerthat terrestrial crater production rates derived by Shoemaker(1998) indicate 340 +- 170 D gt 20 km craters formed over the last120 Myr Using f = 25 we get the same value a D gt 08 km asteroidmakes a D gt 20 km crater and they hit Earth every 035 Myr onaverage (eg Bottke et al 2002) for a total of ~340 over 120 MyrAccordingly we predict Chicxulub and Popigai were made by D ~ 7and D ~ 4 km asteroids respectively values close to their predicted

2

1 11 1 1

2 1

35

2

2 22 2

1 1

2 22 2 2

6 6 3 78 5 4 1

1 12 2

26

sizes from IrOs measurements This result also potentiallyexplains why Chicxulub formed ~65 Myr ago the interval betweenD ~ 7 km impacts on Earth is close to this rateThe NEO model by Bottke et al (2002) also suggests asteroids hitVenus at roughly the same rate as Earth Fitting model craters toobservations we estimate Venusrsquo average surface age as ~130 Myra lower value than previous predictions This result if true hasinteresting implications for Venusrsquos evolutionary history

Author(s) William Bottke Rebecca Ghent Sara Mazrouei Stuart Robbins David VokrouhlickyInstitution(s) 1 Charles U 2 Southwest Research Inst 3 UToronto

20108 ndash Sesquinary catanae on Phobos fromreaccretion of ejected materialImpact ejecta from a planetary satellite can reimpact the targetbody or nearby companions after an extended period creating adistinct type of lsquosesquinaryrsquo impact morphology We presentresults of a comprehensive survey of sesquinary ejecta releasedfrom the Martian satellite Phobos ranging from ejecta from theStickney impact (outcomes of SPH simulations) to just-escapingejecta particles (Z-model formulation) released from locations atwhich Phobos both overflows its Roche lobe and is inside that lobe(sub and anti-Mars points) Third body solar perturbations andhigh-order harmonics terms are implemented in a highly accurateephemerides formulation to model the dynamical evolution ofejecta in the Mars gravity system and chart locations of eventualreaccretions for comparison with Phobos crater morphologyThe slowest ejecta is found to reaccrete in multiple low-velocitychain-like clusters similar to catanae observed on Ganymede Callisto and Mars on characteristic timescales of 1-10 yearsThe morphological similarity to linear pitted chains on Phobossuggests that this formation mechanism may constrain families ofgrooves that do not fit well to a tidal model for groove origin Ejecta released from a primordial Phobos orbit about Mars donot result in catanae implying that these are geologically recentand no older than Phobosrsquos modern orbit Work is ongoing toconstruct a more detailed correlation between sesquinary catenaeand pitted grooves on Phobos and possible source cratersLongitudinal and latitudinal variations in the location of theprimary cratering event velocity distributions from 1-10 kmcraters orbital position with relation to Mars and conjunctions withDeimos are all treated as free parameters catanae-like clusters arefound in all cases This persistence suggests that the creation oflow-velocity clustered impact structures from sesquinary ejecta is arelatively frequent process on Phobos its effect on surface geologyhas implications for theories surrounding the origin of the familiesof grooves[1] Zahnle et al 2008 Icarus [2] Melosh amp Schenk 1993 Nature[3] Ferrill et al 2004 GSA Today [4] Asphaug et al 2015 EPSC[5] Yoder 1982 Icarus

Author(s) Michael Nayak Erik AsphaugInstitution(s) 1 Arizona State University 2 University ofCalifornia Santa Cruz

20109 ndash Surface Evolution from Orbital Decay onPhobosPhobos the innermost satellite of Mars displays an extensivesystem of grooves that are mostly symmetric about its sub-Marspoint Phobos is steadily spiraling inward due to the tides it raisesand will suffer tidal disruption before colliding with Mars Wecalculate the surface stress field of the de-orbiting satellite andshow that the first signs of tidal disruption are already present onits surface Most of Phobosrsquo prominent grooves have an excellentcorrelation with computed stress orientations The model predictsan interior that has very low strength on the tidal evolutiontimescale overlain by a ~10-100 m exterior shell that has elasticproperties similar to lunar regolithShortly after the Viking spacecraft obtained the first geomorphicimages of Phobos it was proposed that stresses from orbital decaycause grooves But assuming a homogeneous Phobos it provedimpossible to account for the build-up of failure stress in the

exterior regardless of the value assumed for Phobosrsquo rigidityHence the tidal model languished Here we revisit the tidal originof surface fractures with a more detailed treatment that shows theproduction of significant stress in a surface layer with a very strongcorrelation to the geometry of groovesOur model results applied to surface observations imply thatPhobos has a rubble pile interior that is nearly strengthless Alunar-like cohesive regolith outer layer overlays the rubble pileinterior This outer layer behaves elastically and can experiencesignificant tidal stress at levels able to drive tensile failure Fissurescan develop as the global body deforms due to increasing tidesrelated to orbital decay Phobos may have an active and evolvingsurface an exciting target for further exploration The interiorpredictions of this model can be evaluated by future detailedstudies performed by an orbiter or lander

Author(s) Terry Hurford Erik Asphaug Joseph Spitale Douglas Hemingway Alyssa Rhoden Wade Henning BruceBills Simon Kattenhorn Matthew WalkerInstitution(s) 1 Arizona State University 2 ConocoPhillipsCompany 3 JPL 4 NASA GSFC 5 Planetary Science Institute 6University of California Los Angeles 7 University of CaliforniaSanta Cruz

202 ndash EPO - Scientists Showcase20201 ndash Science Communication at NASAScientists usually excel in a particular discipline but generally havea difficult time informing and engaging the public about what wedo From climate science to natural hazards risks our science doesaffect peoples lives Within NASA we have started sciencecommunications training focusing on how to tell a clear storyabout not just what we do but why we do it This not only will helpus better communicate to our stakeholders and the public but alsohopefully make for better communications within our diverseteams

Author(s) Ellen R StofanInstitution(s) 1 NASA

20202 ndash Confessions of an Accidental EPOnomerfrom in Front of the Camera and Behind the PixelsThe various techniques styles and venues for popularizing theresearch outputs from our planetary science community reflect thediversity of the community itself While some are eloquent publicspeakers or gifted writers other colleagues are regularly sought fortelevision appearances or for artwork to illustrate press releasesWhatever the method or medium the collection of experiences wehave had in lsquogetting the word outrsquo represents a valuable resourcepool of ideas and lessons learned from which we can all learn andimprove I will share some of my experiences from working with anumber of television productions and magazine editors with somethoughts on contemporary television production styles I will alsodiscuss life as both a planetary scientist and digital artist and sharesome resources that are ready willing and quite able to help tellthe visual story of your research

Author(s) Daniel D DurdaInstitution(s) 1 Southwest Research Inst

20203 ndash Hazardous Asteroids Cloaking STEM SkillsTraining within an Attention-Grabbing ScienceMathCourseA graduate-level course was designed and taught during thesummer months from 2009 ndash 2015 in order to contribute to thetraining and professional development of K-12 teachers residing inthe Southwest The teachers were seeking Masterrsquos degrees via theNew Mexico Institute of Mining and Technologyrsquos (NMTrsquos)Masters of Science Teaching (MST) program and the coursesatisfied a science or math requirement The MST programprovides opportunities for in-service teachers to enhance theircontent backgrounds in science mathematics engineering andtechnology (SMET) The ultimate goal is to assist teachers in

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[1]

[2][2] [3]

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gaining knowledge that has direct application in the classroomThe engaging topic area of near-Earth object (NEO)characterization studies was used to create a fun and excitingframework for mastering basic skills and concepts in physics andastronomy The objective was to offer a class that had theappropriate science rigor (with an emphasis on mathematics)within a non-threatening format The course entitled ldquoHazardousAsteroidsrdquo incorporates a basic planetary physics curriculum withchallenging laboratories that include a heavy emphasis on mathand technology Since the authors run a NASA-funded NEOresearch and follow-up program also folded into the course is theuse of the Magdalena Ridge Observatoryrsquos 24-meter telescope soparticipants can take and reduce their own data on a near-EarthasteroidIn exit assessments the participants have given the courseexcellent ratings for design and implementation and the overalldegree of satisfaction was high This validates that awell-constructed (and rigorous) course can be effective inreceptively reaching teachers in need of basic skills refreshmentMany of the teachers taking the course were employed in schooldistricts serving at-risk or under-prepared students and the coursehelped provide them with the confidence vital to developing newstrategies for successful teaching

Author(s) Eileen V Ryan William H RyanInstitution(s) 1 NM TechMRO

20204 ndash Blending Entertainment Education andScience in a Modern Digital PlanetariumStudents at the University of Arizona have a relatively rareopportunity to learn in a state-of-the-art planetarium Originallyopened as a campus planetarium in 1975 the Flandrau ScienceCenter recently expanded into the digital realm In 2014 Flandraursquosantique Minolta star projector was joined by a full-dome 4K digitalprojection system powered by a high performance computercluster Currently three science courses are taught in theplanetarium for non-science majors mdash stellar astronomyastrobiology and planetary science (taught by SJK)The new digital system allows us to take our classes off the surfaceof Earth on a journey into the cosmos Databases from dozens ofspacecraft missions and deep-space telescopic surveys are tappedby the software to generate a realistic immersive 3D perspective ofthe universe from local planets satellites and rings to distant starsand galaxies all the way out to the limit of the visible universeSimple clicks of a mouse allow us to change the orientationtrajectory and speed of the virtual spacecraft giving our studentsdiverse views of different phenomenaThe challenge with this system is harnessing the entertainmentaspect for educational purposes The visualization capabilities allowus to artificially enhance certain features and time scales Forexample the sizes of Earth and the moon can be enlargedon-the-fly to help demonstrate phases and eclipses Polar axes andlatitude lines can be added to Earth as it orbits the sun to helpconvey the reasons for seasons Orbital paths can be highlighted toallow students to more accurately comprehend the population ofnear-Earth asteroidsThese new immersive computer-generated visualizationtechniques have the potential to enhance comprehension inscience education especially for concepts involving 3D spatial andtemporal relationships Whether or not this potential is beingrealized will require studies to gauge student learning and retentionbeyond the short-term semester-long course This work is justbeginning

Author(s) Stephen J KortenkampInstitution(s) 1 Planetary Science Institute

20205 ndash Going Above amp Beyond Astronomy as thePublicrsquos Gateway to ScienceMany of the worldrsquos most pressing scientific issues fall outside thepurview of astronomy Climate change vaccination geneticmodification and other similar topics are embroiled in the trenchesof an ideological war in the public sphere which creates asometimes-insurmountable obstacle to discussion This talk will

describe a show series developed at Fiske Planetarium that uses thepublicrsquos remarkable appetite for space content as a means forengaging indirectly with these contentious topics It also promotesthe planetarium as a place for interdisciplinary learning and offersthe opportunity for the broader population to engage with youngscientists in a different light

Author(s) Morgan RehnbergInstitution(s) 1 CULASP

20206 ndash Investigating Changes in Studentsrsquo AttitudesTowards Science During an Adaptive OnlineAstrobiology CourseOnline education is an emergent sector of formal education andArizona State University (ASU) is a leader in offering onlinecourses One that garners very strong positive feedback on studentsurveys is Habitable Worlds which is an interdisciplinary onlinescience course offered every semester since Fall 2011 Primarygoals of this course are to teach understanding of scientificreasoning and practices by using principles from trans-disciplinaryresearch in astrobiology To examine course outcomes weadministered the Classroom Undergraduate Research Experience(CURE) survey which has been previously developed to measurestudent experiences Here we use the survey for the first time foran online course The survey was taken before and after completingthe course during the Fall 2014 and Spring 2015 semesters (N =544) Here we present studentsrsquo views of science represented by 22questions on the survey For the questions students respondedeither not applicable strongly disagree disagree neutralagree or strongly agree In order to interpret the data wedivided the questions into three broader categories for analysisstudentsrsquo understanding of the scientific process studentsrsquoscientific self-efficacy and studentsrsquo views on science teaching Westudy how the sample of students changed their responses to eachof the questions as a group by using a paired-samples sign test togauge the statistical significance of the difference between pre andpost responses We further analyze how individual studentschanged their responses For example we designated a changefrom ldquostrongly disagreerdquo to ldquodisagreerdquo differently than a changefrom ldquoagreerdquo to ldquodisagreerdquo since the latter indicated a notablechange in the studentrsquos opinion We found statistically significantchanges on 12 of the 22 questions These early results indicate thatthere are measurable changes on several identified courseobjectives By measuring changes that occurred to the whole groupof students as well as identifying in detail what type of changesoccurred from student to student for each question we will be ableto improve future offerings of the course as well as to make broaderconclusions about online science education

Author(s) Viranga Perera Sanlyn R Buxner LevHorodyskyj Ariel Anbar Steven Semken Chris Mead DavidLopattoInstitution(s) 1 Arizona State University 2 Grinnell College 3University of Arizona

20207 ndash The Arecibo Observatory Space AcademyThe Arecibo Observatory Space Academy (AOSA) is a ten (10) weekpre-college research program for students in grades 9-12 Ourmission is to prepare students for academic and professionalcareers by allowing them to receive an independent andcollaborative research experience on topics related to space andaide in their individual academic and social development Ourobjectives are to (1) Supplement the studentrsquos STEM education viainquiry-based learning and indirect teaching methods (2) Immersestudents in an ESL environment further developing their verbaland written presentation skills and (3) To foster in every studentan interest in science by exploiting their natural curiosity andknowledge in order to further develop their critical thinking andinvestigation skills AOSA provides students with the opportunityto share lectures with Arecibo Observatory staff who haveexpertise in various STEM fields Each Fall and Spring semesterselected high school students or Cadets from all over Puerto Ricoparticipate in this Saturday academy where they receive experiencedesigning proposing and carrying out research projects related to

1 1

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space exploration focusing on four fields PhysicsAstronomyBiology Engineering and Sociology Cadets get the opportunity toexplore their topic of choice while practicing many of thefoundations of scientific research with the goal of designing a spacesettlement which they present at the NSS-NASA Ames SpaceSettlement Design Contest At the end of each semester studentspresent their research to their peers program mentors and AreciboObservatory staff Funding for this program is provided by NASASSERVI-LPI Center for Lunar Science and Exploration with partialsupport from the Angel Ramos Visitor Center through UMET andmanagement by USRA

Author(s) Linda A Rodriguez-Ford Luisa Zambrano-Marin Bryan M Petty Elizabeth Sternke Andrew M Ortiz Edgard G Rivera-ValentinInstitution(s) 1 Arecibo Observatory

20208 ndash Promoting Diversity in STEM through ActiveRecruiting and Mentoring The Pre-Major inAstronomy Program (Pre-MAP) at the University ofWashingtonThe Pre-Major in Astronomy Program (Pre-MAP) is a research andmentoring program for underclassmen and transfer studentsoffered by the University of Washington Astronomy Departmentsince 2005 The primary goal of Pre-MAP is to recruit and retainstudents from groups traditionally underrepresented in sciencetechnology engineering and mathematics (STEM) through earlyexposure to research The Pre-MAP seminar is the core componentof the program and offers instruction in computing skills datamanipulation science writing statistical analysis and scientificspeaking and presentation skills Students choose research projectsproposed by faculty post-docs and graduate students in areasrelated to astrophysics planetary science and astrobiologyPre-MAP has been successful in retaining underrepresentedstudents in STEM fields relative to the broader UW population andweve found these students are more likely to graduate and excelacademically than their peers As of spring 2015 more than onehundred students have taken the Pre-MAP seminar and bothinternal and external evaluations have shown that all groups ofparticipating students report an increased interest in astronomyand science careers at the end of the seminar Several formerPre-MAP students have obtained or are pursuing doctoral andmasterrsquos degrees in STEM fields many more work at NASAcenters teaching colleges or as engineers or data analysts Pre-MAP student research has produced dozens of publications inpeer-reviewed research journals This talk will provide an overviewof the program the structure of the seminar examples of projectscompleted by students cohort-building activities outside theseminar funding sources recruitment strategies and the aggregatedemographic and achievement data of our students It is our hopethat similar programs may be adopted successfully at otherinstitutions

Author(s) Edward Schwieterman Breanna Binder Michael Tremmel Kristen Garofali Eric Agol VictoriaMeadowsInstitution(s) 1 University of Washington

20209 ndash Scientist-Educator Partnerships theCornerstone of Astrophysics EPOFor nearly two decades NASA has partnered scientists andeducators by embedding Education and Public Outreach (EPO)programs and funding in its science missions and researchactivities This enables scientist and educators to work side-by-sidein translating cutting-edge NASA science and technology forclassrooms museums and public venues

The Office of Public Outreach at the Space Telescope ScienceInstitute (STScI) is uniquely poised to foster collaboration betweenscientists with content expertise and educators with pedagogyexpertise As home to both Hubble Space Telescope and the futureJames Webb Space Telescope STScI leverages the expertise of itsscientists to create partnerships with its collocated Education Teamto translate cutting-edge NASA science into new and effective

learning tools In addition STScI is home of the NASA ScienceMission Directorate (SMD) Astrophysics Science EPO Forumwhich facilitates connections both within the SMD EPOcommunity and beyond to scientists and educators across all NASAAstrophysics missions These collaborations strengthenpartnerships build best practices and enhance coherence forNASA SMD-funded EPO missions and programs

We will present examples of astronomersrsquo engagement in our EPOefforts such as NASA Science4Girls

Author(s) Bonnie K Meinke Denise A Smith BrandonLawton Bonnie Eisenhamer Hussein JirdehInstitution(s) 1 STScI

203 ndash Centaurs Trans-Neptunian Objectsand the Inner Oort Cloud20301 ndash Rotational properties of the Haumea familymembers and candidates Short-term variabilityHaumea is one of the largest known Trans-Neptunian Objects(TNOs) with several anomalous characteristics It is a fast rotatorwith a double-peak period of 392 h Its spectrum is dominated bywater ice features and the high albedo suggests nearly pure waterice on the surface It has two known satellites and a family of atleast ten TNOs with very similar proper orbital parameters andspectral properties The formation of this peculiar family (Haumeaits two moons and dynamically related bodies) is not wellunderstood despite various models that have been proposed duringthe past few yearsIn order to improve our understanding of the formation of thisfamily we have examined the rotational properties of the familymembers and candidates (ie objects with similar proper orbitalelements to the family members but without water ice on theirsurface or without observations to detect surface water) We reportnew short-term variability for 5 family members and 7 candidatesfrom data collected over the past five years using multipleground-based facilities Thanks to our study all the Haumea familymembers have a short-term variability studyFrom rotational data assuming fluid-like rubble-pile structure weconstrain ellipsoidal axis ratios for individual objects and set alower limit to densities We also compared lightcurve amplitudeand rotational frequency distributions for the family memberscandidates and unrelated TNOs to search for additional clues tothe progenitor and the formation of this family

Author(s) Audrey Thirouin Scott S Sheppard Keith SNoll Nicholas A Moskovitz Alain Doressoundiram Institution(s) 1 DTM Carnegie Institution for Science 2 LESIA- Observatory of Paris 3 Lowell Observatory 4 NASA-GoddardSpace Flight Center

20302 ndash Near-Infrared and Optical colors of Trans-Neptunian Objects and Centaurs from Ground-BasedObservations in Support of Spitzer ObservationsTrans-Neptunian objects and Centaurs are small icy bodies locatedbeyond the orbit of Neptune and between the orbits of Neptuneand Jupiter respectively These objects are composed of organicmaterial of silicate minerals and of different ices including H OCH N and CH OH Determining the composition of such objectusually requires spectroscopic measurements on large telescopesHowever we can constrain the compositions of these objects bymeasuring their near-infrared colors that -- in combination withexisting data from the Spitzer Space Telescope -- can indicatesurface composition We will present near-infrared magnitudesand colors of at least 24 trans-Neptunian objects and 3 Centaursobtained in ground-based observations We observed with GeminiUKIRT and the 90 Bok Telescope on Kitt Peak between 2011 and2015 The combination of our data with existing Spitzer SpaceTelescope data enables us to identify spectral slope up to 45 μmand provides rough information on spectral bands which areimportant clues on the surface composition of our targets We willpresent preliminary results on the compositional analysis for select

11 1 1 1

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3 14 3 2

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targets This work was supported by the Spitzer Science Center andNASAs Planetary Astronomy program

Author(s) Cassandra Lejoly Michael Mommert DavidTrilling Noemi Pinilla-Alonso Josh Emery Chad Melton Don McCarthy Craig KulesaInstitution(s) 1 Department of Astronomy - University ofArizona 2 Department of Earth and Planetary Science -University of Tennessee 3 Department of Physics and Astronomy- Northern Arizona University

20303 ndash The color-magnitude distribution of smallKuiper Belt objectsOccupying a vast region beyond the ice giants is an extensiveswarm of minor bodies known as the Kuiper Belt Enigmatic intheir formation composition and evolution these Kuiper Beltobjects (KBOs) lie at the intersection of many of the mostimportant topics in planetary science Improved instruments andlarge-scale surveys have revealed a complex dynamical picture ofthe Kuiper Belt Meanwhile photometric studies have indicatedthat small KBOs display a wide range of colors which may reflect achemically diverse initial accretion environment and provideimportant clues to constraining the surface compositions of theseobjects Notably some recent work has shown evidence forbimodality in the colors of non-cold classical KBOs which wouldhave major implications for the formation and subsequentevolution of the entire KBO population However these previouscolor measurements are few and mostly come from targetedobservations of known objects As a consequence the effect ofobservational biases cannot be readily removed preventing onefrom obtaining an accurate picture of the true color distribution ofthe KBOs as a wholeWe carried out a survey of KBOs using the Hyper Suprime-Caminstrument on the 82-meter Subaru telescope Our observingfields targeted regions away from the ecliptic plane so as to avoidcontamination from cold classical KBOs Each field was imaged inboth the grsquo and irsquo filters which allowed us to calculate the grsquo-irsquo colorof each detected object We detected more than 500 KBOs over twonights of observation with absolute magnitudes from H=6 toH=11 Our survey increases the number of KBOs fainter than H=8with known colors by more than an order of magnitude We findthat the distribution of colors demonstrates a robust bimodalityacross the entire observed range of KBO sizes from which we cancategorize individual objects into two color sub-populations -- thered and very-red KBOs We present the very first analysis of themagnitude distributions of the two color sub-populations

Author(s) Ian Wong Michael E BrownInstitution(s) 1 CALTECH

20304 ndash The Outer Solar System Origins Survey coldclassicals beyond the 21 resonanceWith the 85 characterised discoveries from the first quarter of theongoing Outer Solar System Origins Survey (OSSOS) withMegaPrime on the Canada-France-Hawaii Telescope we find thatthe CFEPS L7 model of Petit et al 2011 remains an accurateparameterization of the classical Kuiper belts orbital structure andthe population estimate for the main belt remains unchanged (for39 AU lt a lt 47 AU) We independently confirm the existence ofsubstructure within the main classical Kuiper belt The semi-majoraxis distribution of the stirred component of the cold classicalsmust contain a clumped lsquokernelrsquoWe detect an extension of the cold classical Kuiper belt thatcontinues at least several AU beyond the 21 mean motionresonance with Neptune This extension would have strongcosmogonic implications for the origin of the classical belts orbitalsubstructureWe will discuss how the 140 new objects we discovered in thesecond quarter of OSSOS place further constraints on coldclassicals beyond the 21 resonance Our 16-18 monthobservational arcs and improved astrometric technique continue toachieve extremely high-quality measurements of TNO orbitsfractional semimajor axis uncertainties of our discoveries areconsistently in the range 001-01 allowing rapid orbital

classification

Author(s) Michele T Bannister J J Kavelaars BrettGladman Jean- Marc Petit Stephen Gwyn Kathryn Volk Ying- Tung Chen Mike AlexandersenInstitution(s) 1 ASIAA 2 Institut UTINAM - UMR CNRS 3NRC Herzberg 4 University of Arizona 5 University of BritishColumbia 6 University of Victoria

20305 ndash Resonant Trans-Neptunian PopulationsConstraints from the first quarter of the Outer SolarSystem Origins SurveyThe first two observational sky blocks of the Outer Solar SystemOrigins Survey (OSSOS) have nearly doubled the set ofwell-characterized observed trans-Neptunian objects (TNOs) thatoccupy mean motion resonances with Neptune We describe the 31securely (plus 8 insecurely) resonant TNOs detected by OSSOS sofar and use them to independently verify the resonant populationmodels from the Canada France Ecliptic Plane Survey with whichwe find broad agreement One of the OSSOS blocks described hereis well-suited to detecting objects trapped at very low librationamplitudes in Neptunes 32 mean motion resonance a dynamicalpopulation of interest in testing the origins of resonant TNOs Wehave detected three plutinos (32 objects) with libration amplitudesless than 20 degrees which requires that plutino librationamplitude distribution be extended to lower values Using theOSSOS detections of 52 objects we confirm that this resonance ismore populated than predicted by models of the outer SolarSystems early dynamical history our minimum populationestimate shows that just the high eccentricity (egt035) portion ofthe resonance are at least as populous as the 21 resonance andpossibly as populated as the 32 resonance The OSSOS 21detections confirm that the 21 resonance has a dynamically colderinclination distribution than either the 32 or 52 resonancesUsing the combination of OSSOS and CFEPS detections of 21objects we constrain the fraction of 21 objects in the symmetricmode of libration to be 02--085 (the rest being asymmetric) wealso constrain the ratio of leading to trailing asymmetric librators (aratio that has been theoretically predicted to vary depending onNeptunes migration history) to be 005--08 at 95 confidenceThese constraints will be improved by future OSSOS blocks

Author(s) Kathryn Volk Ruth Murray-Clay BrettGladman Samantha Lawler Michele Bannister JJKavelaars Jean-Marc Petit Stephen Gwyn MikeAlexandersen Ying-Tung Chen Patryk Sofia Lykawka WingIp Hsing Wen LinInstitution(s) 1 Academia Sinica 2 Kinki University 3National Central University 4 NRC-Herzberg 5 Observatoire deBesancon Universite de Franche Comte 6 The University ofArizona 7 University of British Columbia 8 University ofCalifornia Santa Barbara 9 University of Victoria

20306D ndash Exploring the Outer Neptune ResonancesConstraints on Solar System EvolutionThe long-term evolution of objects in the outer n1 resonances withNeptune provide clues to the evolutionary history of the SolarSystem Based on 4 objects with semi-major axes near the 51resonance we estimate a substantial and previously unrecognizedpopulation of objects perhaps more significant than the populationin the 32 (Plutino) resonance These external resonances arelargely unexplored in both observations and dynamicalsimulations However understanding the characteristics andtrapping history for objects in these populations is critical forconstraining the dynamical history of the solar system The 4objects detected in the Canada-France Ecliptic Plane Survey(CFEPS) were classified using dynamical integrations Three areresonant and the fourth appears to be a resonance diffusionobject part of a population which exited the resonance throughchaotic diffusion The 3 resonant objects are taken to berepresentative of the resonant population so by using thesedetections and the CFEPS characterization (pointings anddetection limits) we calculate a population estimate for thisresonance at ~1900(+3300 -1400) objects with Hglt8 [Pike et al

3 33 2 2 3

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6 65 2 3 4

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6 87 9 99 5 4

7 1 23 3

30

2015] This is at least as large as the Plutinos (32 resonance) at90 confidence The small number of detected objects results insuch a large population estimate due to the numerous biasesagainst detecting objects with semimajor axes at ~88AU Thedynamical behavior of the known objects suggests that thetrapping mechanism for the 51 resonance is resonance stickingfrom the scattering objects Based on our results from the 51resonance we have begun a project to examine the long termevolution of the other n1 resonances to determine the importanceof resonance diffusion and transfer between libration islandsamong the scattering-captured members of those populations

Author(s) Rosemary E Pike JJ Kavelaars Cory JShankman Jean-Marc Petit Gladman Brett Kat Volk MikeAlexandersenInstitution(s) 1 Institut UTINAM 2 Institute of Astronomy ampAstrophysics Academia Sinica 3 NRC Herzberg 4 University ofArizona 5 University of British Columbia 6 University ofVictoria

20307 ndash Searching for Extreme Kuiper Belt Objectsand Inner Oort Cloud ObjectsSince late 2012 we have been performing the largest and deepestsurvey for distant solar system objects In the nearly one thousandsquare degrees we have covered so far we have discovered theobject with the most distant perihelion known (2012 VP113)several extreme Kuiper Belt objects with moderate perihelia andlarge eccentricities one of the top ten intrinsically brightest Trans-Neptunian objects an ultra-wide Kuiper Belt binary one of themost distant known active comets and two active asteroids in themain belt of asteroids The Kuiper Belt population has an outeredge at about 50 AU Sedna and our recent discovery 2012 VP113are the only known objects with perihelia significantly beyond thisedge at about 80 AU These inner Oort cloud objects obtained theirorbits when the solar system was vastly different from now Thusthe dynamical and physical properties of objects in this region offerkey constraints on the formation and evolution of our solar systemWe will discuss the most recent results of our survey

Author(s) Scott S Sheppard Chad Trujillo Dave TholenInstitution(s) 1 Carnegie Inst of Washington 2 GeminiObservatory 3 University of Hawaii

20308 ndash Three steps toward understanding thedynamical structure of the Kuiper belt (and what itmeans for Neptunes migration)Much of the dynamical structure of the Kuiper belt can beexplained if Neptune migrated over several AU andor if Neptunewas scattered to an eccentric orbit during planetary instabilityStep 1 An outstanding problem with the previousmigrationinstability models is that the distribution of orbitalinclinations they predict is narrower than the one inferred fromobservations Here we perform numerical simulations of theKuiper belt formation starting from an initial state with Neptune at20lta_Nlt30 AU and a dynamically cold outer disk extending frombeyond a_N to 30 AU Neptunes orbit is migrated into the disk onan e-folding timescale 1 lt tau lt 100 Myr A small fraction of thedisk planetesimals become implanted into the Kuiper belt in thesimulations We find that the inclination constraint implies thatNeptunes migration was slow (tau gt 10 Myr) and long range (a_Nlt 25 AU)Step 2 A particularly puzzling and up-to-now unexplained featureof the Kuiper belt is the so-called `kernel a concentration of orbitswith semimajor axes a=44 AU eccentricities e=005 andinclinations ilt5 deg Here we show that the Kuiper belt kernel canbe explained if Neptunes migration was interrupted by adiscontinuous change of Neptunes semimajor axis when Neptunereached 28 AU (jumping-Neptune model)Step 3 The existing migrationinstability models invariably predictan excessively large resonant population while observations showthat the non-resonant orbits are in fact more common (egPlutinos in the 32 resonance represent only ~13 of the main beltpopulation) Here we show that the observed population statisticimplies that Neptunes migration was grainy as expected from

scattering encounters of Neptune with massive planetesimals Ourpreferred fit to observations suggests that the outer planetesimaldisk below 30 AU contained ~2000 bodies with mass comparableto that of PlutoTogether these results imply that Neptunes migration was slowlong-range and grainy and that Neptune radially jumped by ~05AU when it reached 28 AU This is consistent with Neptunesorbital evolution obtained in the recently developed models ofplanetary instabilitymigration (Nesvorny amp Morbidelli 2012 AJ144)

Author(s) David NesvornyInstitution(s) 1 SWRI

20309 ndash Into the Kuiper Belt New HorizonsPost-PlutoNew Horizons is now beyond Pluto and flying deeper into theKuiper Belt In the summer of 2014 a Hubble Space TelescopeLarge Program identified two candidate Cold Classical Kuiper BeltObjects (KBOs) that were within reach of New Horizons remainingfuel budget Here we present the selection of the Kuiper Belt flybytarget for New Horizons post-Pluto mission our state ofknowledge regarding this target and the potential 2019 flyby thestatus of New Horizons targeting maneuver and prospects fornear-future long-range observations of other KBOs

Author(s) Alex Harrison Parker John Spencer SusanBenecchi Richard Binzel David Borncamp Marc Buie Cesar Fuentes Stephen Gwyn JJ Kavelaars Keith Noll Jean-Marc Petit Simon Porter Mark Showalter S AlanStern Ray Sterner David Tholen Anne Verbiscer HalWeaver Amanda ZangariInstitution(s) 1 GSFC 2 IfA 3 JHU-APL 4 MIT 5 NAU 6NRC 7 Observatoire de Besancon 8 PSI 9 SETI Institute 10Southwest Research Institute 11 STScI 12 University of Virginia

204 ndash Asteroid Radar amp Thermal StudiesMicrowaved and Served Hot20401 ndash Thermal inertia of eclipsing binary asteroidsthe role of component shapeThermal inertia controls the temperature distribution on asteroidsurfaces This is of crucial importance to the Yarkovsky effect andfor the planning of spacecraft operations on or near the surfaceAdditionally thermal inertia is a sensitive indicator for regolithstructureA uniquely direct way of measuring thermal inertia is throughobservations of the thermal response to an eclipse in a binarysystem when one component shadows the other This method waspioneered by Mueller et al (2010) who observed eclipses in (617)Patroclus using Spitzer IRS Buie et al (2015) report observationsof a stellar occultation by Patroclus Their estimate for the systemsprojected size agrees well with the Spitzer result However theoccultation revealed that the components are much more oblatelyshaped than was assumed by Mueller et alThis prompted us to study the role of component shape in theanalysis of thermal eclipse data Conceivably the global shape canhave a significant impact on the shape and size of the eclipsed areaand therefore on its thermal emission So far this has not beenstudied in a systematic way Using Patroclus and the existingSpitzer data as our test case we vary the ellipsoidal componentshape and determine the resulting best-fit thermal inertia This willlead to an updated estimate of Patroclus thermal inertia alongwith a potentially more realistic estimate of its uncertainty Beyondthat our results will inform ongoing and future thermal studies ofother eclipsing binary asteroids

Author(s) Michael Mueller Marlies van de WeijgaertInstitution(s) 1 Kapteyn Astronomical Institute U Groningen

20402 ndash Modeling the thermal emission fromasteroid 3 Juno using ALMA observations and theKRC thermal model

6 36 1 5 4

2

1 2 3

1

10 108 4 11 10

5 6 6 17 10 9

10 3 2 123 10

1 1

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Asteroid 3 Juno (hereafter referred to as Juno) discovered 1September 1804 is the 11th largest asteroid in the Main AsteroidBelt (MAB) Containing approximately 1 of the mass in the MAB[1] Juno is the second largest S-type [2]As part of the observations acquired from Atacama LargeMillimetersubmillimeter Array (ALMA) [3] 10 reconstructedimages at ~60kmpixel resolution were acquired of Juno [4] thatshowed significant deviations from the Standard Thermal Model(STM) [5] These deviations could be a result of surfacetopography albedo variations emissivity variations thermalinertia variations or any combinationThe KRC thermal model [6 7] which has been extensively used forMars [eg 8 9] and has been applied to Vesta [10] and Ceres [11]will be used to compare model thermal emission to that observedby ALMA at a wavelength of 133 mm [4] The 10 images acquiredover a four hour period captured ~55 of Junorsquos 721 hourrotation Variations in temperature as a function of local time willbe used to constrain the source of the thermal emission deviationsfrom the STMThis work is supported by the NASA Solar System ObservationsProgramReferences[1] Pitjeva E V (2005) Solar System Research 39(3) 176 [2] BaerJ and S R Chesley (2008) Celestial Mechanics and DynamicalAstronomy 100 27ndash42 [3] Wootten A et al (2015) IAU GeneralAssembly Meeting 29 2237199 [4] arXiv150302650 [astro-phEP] doi 1010882041-82058081L2 [5] Lebofsky LA etaal (1986) Icarus 68 239ndash251 [6] Kieffer H H et al (1977) JGeophys Res 82 4249ndash4291 [7] Kieffer Hugh H (2013)Journal of Geophysical Research Planets Volume 118 Issue 3 pp451-470 [8] Titus T N H H Kieffer and P N Christensen(2003) Science 299 1048ndash1051 [9] Fergason R L et al (2012)Space Sci Rev 170 739ndash773 doi101007s11214-012-9891-3 [10]Titus T N et al (2012) 43rd LPSC held March 19-23 2012 at TheWoodlands Texas LPI Contribution No 1659 id2851 [11] TitusT N (2015) Geophysical Research Letters 42(7) 2130-2136

Author(s) Timothy N Titus Jian-Yang Li Arielle Moullet Mark V SykesInstitution(s) 1 National Radio Astronomy Observatory 2Planetary Science Institute 3 US Geological Survey

20403 ndash Characterizing Asteroid Thermal Propertiesthrough the Laboratory Study of MeteoritesAsteroid thermal diffusivity is critical to understanding its thermalevolution and thermal inertia determines its behavior underYarkovsky effects These properties are both functions of thermalconductivity heat capacity and density Thermal conductivity andheat capacity both vary with temperature while thermalconductivity and density are strongly influenced by microporosityOur survey of low-temperature (175K) heat capacities includesmore than 130 meteorites supplemented by precisiontemperature-sensitive heat capacities for 6 individual samplesHeat capacities (175K) range from 350 JkgK for unweathered ironmeteorites to 530 JkgK with most chondrites between 480 and520 JkgK Heat capacities for unweathered ordinary chondritefalls are within 5 of theoretical models and as a function oftemperature fit a theoretical curve of C =A+BT+CT +DTbetween 77 and 300 K and are consistent with mineral databetween 20 and 300 K (Values for ABCD vary by meteoritetype)Thermal conductivities are strong functions of porosity and below90 K strong functions of temperature Laboratory measurementsof several meteorites indicate that between 90 and 300 K mostthermal conductivities vary little with temperature Below 90 Kthermal conductivity drops off strongly as temperature decreasesAbove 2 porosity and 90 K thermal conductivities correlatelinearly with the inverse of porosity Pore geometry and orientationalso affects thermal conductivity thermal conductivity differsnoticeably for the same meteorite sample depending on thedirection of heat flowGiven these relations and meteorite data thermal diffusivity andthermal inertia can be derived over a range of porosities andtemperatures for most asteroids We see that porosity greatlyinfluences both thermal diffusivity and thermal inertia Even as

little as 20 porosity can reduce thermal diffusivity by two ordersof magnitude from the nonporous case

Author(s) Robert J Macke Guy J Consolmagno Cyril POpeil Daniel T BrittInstitution(s) 1 Boston College 2 University of CentralFlorida 3 Vatican Observatory

20404 ndash The Spherical Brazil Nut Effect and itsSignificance to AsteroidsAsteroids are intriguing remnant objects from the early solarsystem They can inform us on how planets formed they couldpossibly impact the earth in the future and they likely containprecious metals for those reasons there will be future explorationand mining space missions to them Telescopic observations andspacecraft data have helped us understand basic properties such astheir size mass spin rate orbital elements and their surfaceproperties However their interior structures have remainedelusive In order to fully characterize the interiors of these bodiesseismic data will be necessary However we can infer their interiorstructures by combining several key factors that we know aboutthem 1) Past work has shown that asteroids between 150 m to 10km in size are rubble-piles that are a collection of particles heldtogether by gravity and possibly cohesion 2) Asteroid surfacesshow cratering that suggests that past impacts would haveseismically shaken these bodies 3) Spacecraft images show thatsome asteroids have large protruding boulders on their surfaces Arubble-pile object made of particles of different sizes and thatundergoes seismic shaking will experience granular flowSpecifically a size sorting effect known as the Brazil Nut Effect willlead larger particles to move towards the surface while smallerparticles will move downwards Previous work has suggested thatthis effect could possibly explain not only why there are largeboulders on the surfaces of some asteroids but also might suggestthat the interior particles of these bodies would be organized bysize Previous works have conducted computer simulations and labexperiments however all the particle configurations used havebeen either cylindrical or rectangular boxes In this work wepresent a spherical configuration of self-gravitating particles that isa better representation of asteroids Our results indicate that whilefriction is not necessary for the Brazil Nut Effect to take place itaids the sorting process after a certain energy threshold is metEven though we find that the outer layers of asteroids couldpossibly be size sorted the inner regions are likely mixed

Author(s) Viranga Perera Alan P Jackson Erik Asphaug Ronald-Louis BallouzInstitution(s) 1 Arizona State University 2 University ofMaryland

20405 ndash An Investigation of 2D Electrostatic DustLevitation about BennuElectrostatic dust levitation has been hypothesized to occur nearthe surface of asteroids due to the interaction of the solar windplasma and UV radiation with the asteroidsrsquo surfaces and theirnear-zero surficial gravity Dust levitation could provide amechanism to move regolith across the surface of an asteroid Ourpreliminary investigations have identified grains sizes and thealtitudes at which grains may levitate considering a semi-analytical1D plasma model However our initial semi-analytical plasmamodel was not well-suited to the complex terminator region wherethe surface transitions between positive (dominated byphotoemission) and negative (in the plasma wake) potentials Inthis analysis we use a new 2D treecode-based plasma simulation tomore accurately model the plasma environment about a simplifiedcircular cross-section of the asteroid Bennu We investigate thealtitudes and grain sizes where electrostatic levitation could occurat Bennu The improved plasma model will allow more accuratepredictions of dust levitation and deposition particularly in theterminator and wake regions that could not be characterized beearlier plasma models

3 2 12

p (-2) (-05)

3 31 2

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Author(s) Christine Hartzell Michael ZimmermanInstitution(s) 1 Johns Hopkins University Applied PhysicsLaboratory 2 University of Maryland

20406D ndash On physical properties of planetarysurfaces studied by modeling radar scatteringAfter decades of post-discovery characterization and orbitalrefinement of near-Earth objects using planetary radars extensiveliterature describing the radar scattering properties of variousobjects of the Solar System has become available At the same timethere is a shortage of work on what the observed values implyabout the physical properties of the planetary surfaces Our goal isto fill part of this gapWe investigate which physical properties of a planetary surface orsmall body affect the radar echo and how All of the work will becarried out by modeling electromagnetic scattering with theprimary focus in the backscattering direction As all models areonly simplifications of the real world it is necessary to study whichmodels are the best analogies to observations Moreover thenumber of scattering scenarios is near infinite but numericalresources are limited Due to the limitations of specific codesseveral different codes are usedThe simulations reveal in the backscattering direction polarizationenhancement at certain bands of sizes and refractive indices Bystudying spherical inhomogeneous particles we found that theelectric permittivity defines the phase shift caused by the scattererand hence the depolarizing capability of the scatterer By usinglarge irregular particles as the scatterers a systematic effect of theabsorption on the radar observables can be seen which leads to asemi-analytic novel form of the radar scattering laws By usingsmall (wavelength-scale) irregular particles as internal or externaldiffuse medium inside or on the surface of a very large particleradar scattering can be simulated very realistically The resultsmainly support the current understanding of the effects of thesurface geometry the electric permittivity and multiple scatteringWe also explain how the electric permittivity can affect the radaralbedo and circular-polarization ratio by phase shift andabsorption In addition we show that as the polarization is verysensitive to the scatterer geometry simplifications made in thechoice of the geometry can have unprecedented effects

Author(s) Anne Virkki Karri MuinonenInstitution(s) 1 University of Helsinki

20407 ndash Radar imaging of binary near-Earth asteroid(357439) 2004 BL86We report radar imaging of near-Earth asteroid 2004 BL86obtained at Goldstone Arecibo Green Bank and elements of theVery Long Baseline Array between 2015 January 26-31 2004 BL86approached within 00080 au on January 26 the closest knownapproach by any object with an absolute magnitude brighter than~19 until 2027 Prior to the encounter virtually nothing wasknown about its physical properties other than its absolutemagnitude of 19 which suggested a diameter within a factor of twoof 500 m 2004 BL86 was a very strong radar target that providedan outstanding opportunity for radar imaging and physicalcharacterization Delay-Doppler images with range resolutions asfine as 375 m placed thousands of pixels on the object andconfirmed photometric results reported by Pravec et al (2015CBET 4063) that 2004 BL86 is a binary system During theobservations the asteroid moved more than 90 deg and provided arange of viewing geometries The bandwidth was relatively narrowon Jan 26 reached a maximum on Jan 27 and then narrowed onJan 28 a progression indicating that the subradar latitude movedacross the equator during those days The images reveal a roundedprimary with an equatorial diameter of ~350 m evidence forridges possible boulders and a pronounced angular feature ~100m in diameter near one of the poles Images from Jan 26 show arcsof radar-bright pixels on the approaching and receding limbs thatextend well behind the trailing edge in the middle of the echo Thisis the delay-Doppler signature of an oblate shape seen at least a fewtens of degrees off the equator A rough estimate for the diameterof the secondary is ~70 m and its narrow bandwidth is consistentwith the 14-h orbital period reported by Pravec et al (2015) The

images are suitable for 3D shape pole orbit and mass estimationThe observations utilized new data taking equipment at GreenBank to receive X-band (8560 MHz 35 cm) transmissions fromthe 70 m DSS-14 facility and for the first time transmissions usinga new C-band (7190 MHz 42 cm) radar at the 34 m DSS-13antenna at the Goldstone complex

Author(s) Lance A M Benner Marina Brozovic Jon DGiorgini Patrick A Taylor Ellen S Howell Michael W Busch Michael C Nolan Joseph S Jao Clement G Lee H AlysonFord Frank D GhigoInstitution(s) 1 Arecibo Observatory 2 JPL 3 NRAO 4 SETIInstitute

20408 ndash Radar observations of near-Earth asteroid(436724) 2011 UW158 using the Arecibo Goldstoneand Green Bank TelescopesNear-Earth asteroid (436724) 2011 UW158 made a close approachto the Earth on 2015 July 19 at a distance of 0016 au (64 lunardistances) We observed it between July 13-26 using the AreciboS-band (2380 MHz 125 cm) radar the Goldstone X-band (8560MHz 35 cm) radar and the Green Bank Telescope (GBT) Arecibodelay-Doppler observations achieved range resolutions as fine as75 m At the GBT we used a newly installed radar backend torecord the radar echoes which improved signal-to-noise ratios(SNRs) two-fold relative to monostatic reception at the 70-mDSS-14 antenna at Goldstone The higher SNRs allowed us toobtain images with range resolutions comparable to those atArecibo that reveal the asteroidrsquos surface topography with greatdetail The visible extents of the asteroid in the radar imagessuggest an elongated object with dimensions of about 600 x 300 mThe shape of the object is angular with a facet on one side thatspans the entire length of the asteroid Three parallel radar-brightfeatures are visible when the asteroid is oriented broadside andmay represent ridges These features cause unusually largebrightness variations in the echo as the asteroid rotates There areother radar-bright regions that suggest small-scale (tens of meters)topography Repetition of the leading edge profiles in the imagesindicates a spin period of ~37 minutes which is consistent with theperiod that was previously reported using lightcurves (B Gary TLister H K Moon P Pravec and B D Warner pers comm)This spin period is unusually fast among asteroids its size andsuggests that the object has relatively high cohesive strength 2011UW158 has a relatively low delta-V for spacecraft missions and ison NASArsquos Near-Earth Object Human Accessible Targets Study list

Author(s) Shantanu P Naidu Lance A M Benner MarinaBrozovic Jon D Giorgini Joseph S Jao Michael W Busch Patrick A Taylor James E Richardson Edgard G Rivera-Valentin Linda A Ford Frank D Ghigo Adam Kobelski

Institution(s) 1 Arecibo Observatory 2 Jet PropulsionLaboratory California Institute of Technology 3 NRAO 4 SETIInstitute

20409 ndash Potentially Hazardous Asteroid (85989) 1999JD6 Radar Infrared and Lightcurve Observationsand a Preliminary Shape ModelWe report observations of potentially hazardous asteroid (85989)1999 JD6 which passed 0048 AU from Earth (19 lunar distances)during its close approach on July 25 2015 During eleven daysbetween July 15 and August 4 2015 we observed 1999 JD6 withthe Goldstone Solar System Radar and with Arecibo Observatorysplanetary radar including bistatic reception of some Goldstoneechoes at Green Bank We obtained delay-Doppler radar images ata wide range of latitudes with range resolutions varying from 75 to150 meters per pixel depending on the observing conditions Weacquired near-infrared spectra from the NASA InfraRed TelescopeFacility (IRTF) on two nights in July 2015 at wavelengths from075 to 50 microns showing JD6s thermal emission We alsoobtained optical lightcurves from Ondrejov Observatory (in 1999)Table Mountain Observatory (in 2000) and Palmer Divide Station(in 2015) Previous observers had suggested that 1999 JD6 wasmost likely an elongated object based on its large lightcurveamplitude of 12 magnitudes (Szabo et al 2001 Polishook and

2 1

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Brosch 2008 Warner 2014) The radar images reveal an elongatedpeanut-shaped object with two lobes separated by a sharpconcavity JD6s maximum diameter is about two kilometers andits larger lobe is approximately 50 longer than its smaller lobeThe larger lobe has a concavity on its end We will present moredetails on the shape and rotation state of 1999 JD6 as well as itssurface properties from optical and infrared data and thermalmodeling

Author(s) Sean E Marshall Ellen S Howell MarinaBrozović Patrick A Taylor Donald B Campbell Lance A MBenner Shantanu P Naidu Jon D Giorgini Joseph S Jao Clement G Lee James E Richardson Linda A Rodriguez-Ford Edgard G Rivera-Valentin Frank Ghigo AdamKobelski Michael W Busch Petr Pravec Brian D Warner Vishnu Reddy Michael D Hicks Jenna L Crowell Yanga RFernandez Ronald J Vervack Michael C Nolan ChristopherMagri Benjamin Sharkey Brandon BozekInstitution(s) 1 Arecibo Observatory 2 Astronomical InstituteAcademy of Sciences of the Czech Republic 3 Center for SolarSystem Studies 4 Cornell University 5 Jet PropulsionLaboratory 6 Johns Hopkins University Applied PhysicsLaboratory 7 Lunar and Planetary Laboratory University ofArizona 8 National Radio Astronomy Observatory 9 PlanetaryScience Institute 10 SETI Institute 11 University of CentralFlorida 12 University of Maine at Farmington 13 University ofMinnesota 14 University of Texas

205 ndash Titans Atmosphere20501 ndash Seasonal variations in Titanrsquos stratosphereobserved with CassiniCIRS after the northern springequinoxSince 2004 Cassini has made more than 110 Titan flybysobserving its atmosphere with instruments including the CassiniComposite InfraRed Spectrometer (CIRS) We know from CIRSobservations that the global dynamics drastically changed after thenorthern spring equinox that occurred in August 2009 ([1] [2][3] [4]) The pole-to-pole middle atmosphere dynamics (above100 km) experienced a global reversal in less than 2 years after theequinox [4] while the northern hemisphere was entering springThis new pattern with downwelling at the south pole resulted inenrichment of almost all molecules inside the southern polarvortex while a persistent enhancement due to the former northernwinter subsidence is still seen in the north pole region Accordingto General Circulation Model calculations this single circulationcell pattern should remain until 2025We will present new 2015 CIRS limb observations analysis We willshow that many species (C H HCN HC N C H C H CH CCH C H ) are now highly enriched near the south pole byfactors ~100 at 500 km compared to just a few years ago Suchlarge middle atmospheric enrichments were never observed beforeand are similar to in situ results from INMS at 1000 km [5]We will also show that the north pole displays for the first timesince the beginning of the Cassini mission a depletion of moleculargas mixing ratios at altitudes higher than 300 km while deeperlevels remains enriched compared to mid-latitude regionsReferences[1] Teanby N et al Nature 491 pp 733-735 2012[2] Achterberg et al DPS 46 abstract 10207Tucson 2014[3] Coustenis et al DPS 46 abstract 10246 Tucson 2014[4] Vinatier et al Icarus 250 95-115 2015[5] Cui et al Icarus 200 581-615 2009

Author(s) Sandrine Vinatier Bruno Beacutezard Nick Teanby Seacutebastien Lebonnois Richard Achterberg Nicolas Gorius Andrei Mamoutkine F Michael FlasarInstitution(s) 1 Laboratoire de Meacuteteacuteorologie Dynamique 2LESIA Obs de Paris-Meudon 3 NASA Goddard Space FlightCenter 4 School of Earth Science University of Bristol 5 TheCatholic University of America 6 University of Maryland

20502 ndash Post-equinox evolution of Titans

south-polar stratosphereSince northern spring equinox in mid-2009 Titans atmospherehas demonstrated dramatic changes in temperature (Achterberg etal 2014) composition (Teanby et al 2012 Vinatier et al 2015Coustenis et al 2015) and aerosolice distribution (de Kok et al2014 Jennings et al 2015 West et al 2015) Changes have beengreatest at the southern winter pole which continues to enterdeeper into Titans shadow following the 2009 equinoxObservational highlights include development of a south polarhot-spot nitrile ice clouds dense condensate clouds and extremetrace gas concentrationsHere we use recent infrared spectral limb observations byCassiniCIRS to determine the evolution of temperature andcomposition of the south polar region since equinox Ourobservations show that the south polar hot-spot initially observedfollowing equinox has now disappeared and been replaced byextremely low temperatures throughout the stratospheresuspected to be due to enhanced radiative cooling There alsoappears to be an unusual distribution of nitrile species whichsuggests trace gases are now escaping the newly formed wintervortex Thus providing clues to the underlying circulation The newobservations will be presented and implications for Titans polaratmospheric dynamics discussedAchterberg et al (2014) DPS46 10207 TucsonCoustenis et al (2015) Icarus (in press)de Kok et al (2014) Nature 514 65-67Jennings et al (2015) ApJL 804 L34Teanby et al (2012) Nature 491 732-735Vinatier et al (2015) Icarus 250 95-115West et al (2015) Icarus (in press)

Author(s) Nicholas A Teanby Sandrine Vinatier Remco deKok Conor A Nixon Patrick GJ IrwinInstitution(s) 1 AOPP Oxford University 2 LESIA-Observatoire de Paris 3 NASA Goddard Space Flight Center 4SRON Netherlands Institute for Space Research 5 University ofBristol

20503 ndash ALMA Spectroscopy of Titans AtmosphereFirst Detections of Vinyl Cyanide and AcetonitrileIsotopologuesStudies of Titans atmospheric chemistry provide a uniqueopportunity to explore the origin and evolution of complex organicmatter in primitive planetary atmospheres The Atacama LargeMillimetersubmillimeter Array (ALMA) is a powerful newtelescope well suited to the study of molecular emission fromTitans stratosphere and mesosphere Here we present early resultsfrom our ongoing study to exploit the large volume of Titan datataken using ALMA in Early Science Mode (during the period2012-2014) Combining data from multiple ALMA Band 6observations we obtained high-resolution mm-wave spectra withunprecedented sensitivity enabling the first detection of vinylcyanide (C H CN) in Titans atmosphere Initial estimates indicatea mesospheric abundance ratio with respect to ethyl cyanide(C H CN) of [C H CN][C H CN] = 031 In addition we reportthe first detections on Titan of the C and N-substitutedisotopologues of acetonitrile ( CH CN and CH C N) Radiativetransfer models and possible chemical formation pathways forthese molecules will be discussed

Author(s) Martin Cordiner Maureen Y Palmer Conor ANixon Steven B Charnley Michael J Mumma Pat G J Irwin Nick A Teanby Zbigniew Kisiel Joseph SeriganoInstitution(s) 1 NASA Goddard Space Flight Center 2 PolishAcademy of Sciences 3 St Olaf College 4 University of Bristol 5University of Oxford

20504 ndash Observations of CO in Titans AtmosphereUsing ALMAThe advent of the Atacama Large Millimetersubmillimeter Array(ALMA) has provided a powerful facility for probing theatmospheres of solar system targets at long wavelengths (84-720GHz) where the rotational lines of small polar molecules areprominent In the dense nitrogen-dominated atmosphere of Titan

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photodissociation of molecular nitrogen and methane leads to awealth of complex hydrocarbons and nitriles in small abundancesPast millimetersubmillimeter observations includingground-based observations as well as those by the CompositeInfrared Spectrometer (CIRS) aboard the Cassini spacecraft haveproven the significance of this wavelength region for the derivationof vertical mixing profiles latitudinal and seasonal variations andmolecular detections Previous ALMA studies of Titan havepresented mapping and vertical column densities of hydrogenisocyanide (HNC) and cyanoacetylene (HC N) (Cordiner et al2014) as well as the first spectroscopic detection of ethyl cyanide(C H CN) in Titanrsquos atmosphere (Cordiner et al 2015)Here we report several submillimetric observations of carbonmonoxide (CO) and its isotopologues CO C O and C O inTitanrsquos atmosphere obtained with flux calibration data from theALMA Science Archive We employ NEMESIS a line-by-lineradiative transfer code to determine the stratospheric abundancesof these molecules The abundance of CO in Titans atmosphere isdetermined to be approximately 50plusmn1 ppm constant with altitudeand isotopic ratios are determined to be approximately C C =90 O O = 470 and O O = 2800 This report presents thefirst spectroscopic detection of C O in the outer solar systemdetected at gt11σ confidence This talk will focus on isotopic ratiosin CO in Titans atmosphere and will compare our results topreviously measured values for Titan and other bodies in the SolarSystem General implications for the history of Titan frommeasurements of CO and its isotopologues will be discussed

Author(s) Joseph Serigano Conor A Nixon MartinCordiner Patrick G J Irwin Nicholas Teanby Steven BCharnley Johan E Lindberg Anthony J RemijanInstitution(s) 1 Johns Hopkins University 2 NASA GoddardSpace Flight Center 3 National Radio Astronomy Observatory 4Oxford University 5 University of Bristol

20505 ndash Search for methane isotope fractionation dueto Rayleigh distillation on TitanKinetic fractionation of methane isotopes on Titan may bediagnostic of the temperatures where methane is evaporating fromthe surface and condensing in the atmosphere We describe theequilibrium fractionation that is expected to result in a depletion ofCH D in the gas and speculate about the magnitude of thisdepletion We search for spatial variation in CH D using near-IRspectra obtained with Keck NIRSPAO (Aacutedaacutemkovics et al 2015)and describe some limitations of the current methane lineassignments near 155μm in HITRAN2012 After performing arudimentary empirical correction to our radiative transfer modelwe perform retrievals of the CH D abundance Preliminary resultsfrom this work suggest that CH DCH is globally uniform towithin ~10 that is variation in CH D abundance of more than10 of the nominal value would be detectable in our existingobservations Improvements to both the observations and modelsare suggested and we discuss the limitations of our methodology

Author(s) Mate Adamkovics Jonathan L MitchellInstitution(s) 1 University of California 2 University ofCalifornia

20506 ndash Titan Aerosol Formation as a Sink for StableCarbon and Nitrogen IsotopesStable isotope ratios of major elements can be used to infer muchabout local- and global-scale processes on a planet On Titanaerosol production is a significant sink of carbon and nitrogen inthe atmosphere and isotopic fractionation of these elements maybe introduced during the advanced organic chemistry that leads tothe condensed phase products Several stable isotope pairsincluding C C and N N have been measured in situ orprobed spectroscopically by Cassini-borne instruments spacetelescopes or through ground-based observations However theeffect of a potentially critical pathway for isotopic fractionation ndashorganic aerosol formation and subsequent deposition onto thesurface of Titan ndash has not been considered due to insufficient dataregarding fractionation during aerosol formation To betterunderstand the nature of this process we have measured the

isotopic fractionation associated with the formation of Titanaerosol analogs via far-UV irradiation of several methane (CH )and nitrogen (N ) mixturesOur initial results probed the fractionation of the aerosol productrelative to the reactant gases as a function of CH abundance [1]Our results show that the direction of carbon isotope fractionationduring aerosol formation is in contrast to the expected result if thesource of the fractionation is a kinetic isotope effect The resultantfractionation in nitrogen favored the light ( N) isotope in theaerosol with NC ratios varying from 013 ndash 031 Ongoing workincludes probing the effects of pressure and temperature on thedirection and magnitude of the stable isotope fractionation We willpresent results alongside interpretation of the driving processes aswell as implications for Titan if similar fractionation occurredduring aerosol formation in the atmosphere[1] Sebree JA Stern JC Mandt KE Domagal-Goldman SDand Trainer MG C and N Fractionation of CH N Mixturesduring Photochemical Aerosol Formation Relevance to TitanIcarus in press 2015 doi101016jicarus201504016

Author(s) Melissa G Trainer Jennifer C Stern Joshua ASebree Thomas J Gautier Javier A Fuentes Shawn DDomagal-Goldman Kathleen E MandtInstitution(s) 1 NASA Goddard Space Flight Center 2Southwest Research Institute 3 University of Northern Iowa

20507 ndash New results from the analyses of the solidphase of the NASA Ames Titan Haze Simulation (THS)experimentIn Titanrsquos atmosphere a complex chemistry occurs at lowtemperature between N and CH that leads to the production ofheavy organic molecules and subsequently solid aerosols TheTitan Haze Simulation (THS) experiment was developed at theNASA Ames COSmIC facility to study Titanrsquos atmosphericchemistry at low temperature In the THS the chemistry issimulated by plasma in the stream of a supersonic expansion Withthis unique design the gas is cooled to Titan-like temperature(~150K) before inducing the chemistry by plasma and remains atlow temperature in the plasma (~200K) Different N -CH -basedgas mixtures can be injected in the plasma with or without theaddition of heavier molecules in order to monitor the evolution ofthe chemical growthFollowing a recent in situ mass spectrometry study of the gas phasethat demonstrated that the THS is a unique tool to probe the firstand intermediate steps of Titanrsquos atmospheric chemistry at lowtemperature (Sciamma-OrsquoBrien et al Icarus 243 325 (2014)) wehave performed a complementary study of the solid phase Thefindings are consistent with the chemical growth evolutionobserved in the gas phase Grains and aggregates form in the gasphase and can be jet deposited onto various substrates for ex situanalyses Scanning Electron Microscopy images show that morecomplex mixtures produce larger aggregates and that differentgrowth mechanisms seem to occur depending on the gas mixtureThey also allow the determination of the size distribution of theTHS solid grains A Direct Analysis in Real Time mass spectrometryanalysis coupled with Collision Induced Dissociation has detectedthe presence of aminoacetonitrile a precursor of glycine in theTHS aerosols X-ray Absorption Near Edge Structure (XANES)measurements also show the presence of imine and nitrilefunctional groups showing evidence of nitrogen chemistryInfrared and microIR spectra of samples deposited on KBr and Sisubstrates show the presence of more aromatic functional groupsfor more complex gas mixtures and allowed the determination ofthe samplesrsquo thickness These complementary studies show thepotential of THS to better understand Titanrsquos chemistry and theorigin of aerosol formation

Author(s) Ella Sciamma-OBrien Kathleen T Upton Jesse L Beauchamp Farid SalamaInstitution(s) 1 NASA Ames Research Center 2 NoyesLaboratory of Chemical Physics and the Beckman Institute -Caltech

20508 ndash Aerosol properties in Titans upper

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atmosphere from UVIS airglow observationsMultiple Cassini observations reveal that the abundant aerosolparticles in Titans atmosphere are formed at high altitudesparticularly in the thermosphere [1] They subsequently falltowards the lower atmosphere and in their path their size shapeand population change in reflection to the variable atmosphericconditionsAlthough multiple observations can help us retrieve informationfor the aerosol properties in the lower atmosphere [2] we havelimited knowledge for their properties in the altitude range betweentheir formation region in the thermosphere and the upper regionof the main haze layer UVIS is one of a few instruments that canprobe this part of the atmosphere and allow for the retrieval of theaerosol propertiesHere we analyze observations of atmospheric airglow thatdemonstrate the signature of N emissions and light scatteringfrom aerosol particles at different altitudes above 500 km [3] Wefit these observations with a combined model of N airglow [4] andatmospheric scattering by gases and aerosols that allows us toseparate the pure scattering component and retrieve the aerosolsize (distribution) and density We particularly focus onobservations from the T32 flyby that probed high southernlatitudes in 2007 and combine good altitude resolution with highsignal to noise ratio We combine these with observations atdifferent phase angles and observing geometry conditions (nadirvs limb) in order to set better constraints on the aerosol propertiesOur preliminary results demonstrate an increase in the averageparticle size with decreasing altitude in the atmosphere from about10 nm at 800 km to ~50 nm at 500 km and an extinction profile at185 nm wavelength similar to the profile derive from UVISoccultation measurements at lower latitudes [5][1] Lavvas et al 2013 PNAS doi101073pnas1217059110 andreferences therein[2] Tomasko et al 2008 PSS 56 p669 Bellucci et al 2009 Icarus201 p198[3] Ajello et al 2008 GRL 35 L06102[4] Lavvas et al 2015 Icarus 260 p29[5] Koskinen et al 2011 Icarus 216 p507

Author(s) Panayotis Lavvas Tommi Koskinen EmilieRoyer Pascal Rannou Robert A WestInstitution(s) 1 GSMA 2 GSMACNRS 3 JPL 4 LASP 5University of Arizona

20509 ndash Retrievals of Aerosol and HydrocarbonAbundances in the Atmosphere of Titan from CassiniUVIS Stellar Occultation MeasurementsWe present retrievals of haze optical properties and hydrocarbonabundances in the atmosphere of Titan from Cassini UVIS stellaroccultation observations of the upper atmosphere above 300 kmThese measurements focus on the extinction in the far ultraviolet(FUV) wavelengths between 140 and 190 nm and include data frommultiple Titan flybys across several latitudes and longitudesCoherent structures in the optical depth profile are seen to vary bytens of kilometers in altitude across different latitudes while alsovarying temporally on time scales of months and yearsComparisons of these extinction estimates with the results of ouraerosol microphysics model suggest that processes aside fromsedimentation diffusional transport and Brownian coagulation aretaking place The UVIS spectrographs also provide measurement ofthe scattered solar spectrum which can be used to calculate thereal part of the aerosol index of refraction At the same time thephase angle distribution and absolute flux of the scatteredspectrum in combination with the extinction can be used toestimate other physical properties of the scattering particles Thusour results provide valuable constraints for models of Titanphotochemistry and haze formation throughout this region of theupper atmosphere

Author(s) Siteng Fan Joshua A Kammer Peter Gao Mao-Chang Liang Donald E Shemansky Yuk L YungInstitution(s) 1 Division of Geological and Planetary SciencesCalifornia Institute of Technology 2 Planetary and Space ScienceDivision Space Environment Technologies 3 Research Center forEnvironmental Changes Academia Sinica 4 Southwest ResearchInstitute

207 ndash Harold C Urey Prize No Photon LeftBehind How Modern Spectroscopy isTransforming Planetary Sciences GeronimoVillanueva (NASA Goddard Space FlightCenter)20701 ndash No photon left behind How modernspectroscopy is transforming planetary sciencesThe advent of sensitive high-resolution spectrometers and modernanalytical spectroscopic tools is opening new windows in theexploration of planetary atmospheres High-resolution infraredspectrometers with broad spectral coverage at ground-basedobservatories (eg Keck IRTF VLT) and arrays of radio telescopeswith state of the art receivers (eg ALMA) now permit theexploration of the kinematics composition and thermal structureof a broad range of planetary sources with unprecedentedprecision These combined with the advent of comprehensivespectroscopic databases containing billions of lines robustradiative transfer models and unprecedented availablecomputational power are transforming the way we investigateplanetary atmospheresSuch advances have allowed us to obtain the first mapping of waterDH on Mars (Villanueva et al 2015) to obtain one of the mostcomprehensive searches for organics in the Martian atmosphere(Villanueva et al 2013) and to obtain the first measurement ofwater DH of a periodic comet (Villanueva et al 2009)In this talk I will present the current frontiers in the exploration ofplanetary atmospheres and how the synergies between futurespace (eg ExoMars 2016 JWST) and ground astronomical assets(eg TMT E-ELT) will transform our understanding of thecomposition stability and evolution of the atmospheres in theSolar System and beyondVillanueva GL et al 2009 Astrophys J Lett 690 (1) pp L5ndashL9Villanueva GL et al 2013 Icarus 223 (1) pp 11ndash27Villanueva GL et al 2015 Science 348 (6) pp 218ndash221

Author(s) Geronimo Luis VillanuevaInstitution(s) 1 NASA - Goddard Space Flight Center

208 ndash Changing Perspectives on Mercuryand the Moon Brett Denevi (Johns HopkinsAPL)20801 ndash Changing Perspectives on Mercury and theMoonAirless cratered and not so different in size the Moon andMercury form a natural pair in the inner Solar System For decadesafter the 1974 and 1975 Mariner 10 flybys of Mercury with littlecompositional information no concrete evidence for volcanismand images of less than half of the planet it was thought thatMercuryrsquos surface may be similar to the lunar highlands an ancientanorthositic flotation crust subsequently shaped mainly by impactcratering However observations from the recently completedMESSENGER mission to Mercury have upended our view of theinnermost planet revealing for example a crust that may be richin graphite and that has been extensively resurfaced by volcanicactivity and geologic activity that may continue today to produceenigmatic ldquohollowsrdquo ndash a crust very different from that of the MoonMeanwhile the Moon has undergone its own revolution as datafrom recent spacecraft such as the Lunar Reconnaissance Orbiterreveal sites of silicic volcanism indicative of complex differentiation

2

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1 4 13 2 1

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36

in the mantle tectonic activity that may be ongoing recent volcanicactivity that alters the paradigm that volcanism died on the Moonover a billion years ago and evidence that the early chronology ofthe inner Solar System may not be as well known as once thoughtAs our views of these two bodies evolve a new understanding oftheir differences informs our knowledge of the variety of processesand styles of planetary evolution and their similarities point tocommonalities among all airless bodies

Author(s) Brett W DeneviInstitution(s) 1 Johns Hopkins University Applied PhysicsLaboratory

209 ndash Vesta and Ceres by the Light of DawnChristopher Russell (UC Los Angeles)20901 ndash Vesta and Ceres by the light of DawnCeres and Vesta are the most massive bodies in the main asteroidbelt They both appear to be intact protoplanets whose growth mayhave been drastically altered by the concomitant formation ofJupiter These two bodies have witnessed 46 Ga of solar systemhistory much but not all of which has been recorded in theirsurfaces Dawnrsquos objective is to interview these two witnesses tolearn as much as possible about the early epoch These bodies areprotoplanets our best archetypes of the early building blocks of theterrestrial planets In particular siderophile elements in the Earthrsquoscore were probably first segregated in Vesta-like bodies and itswater was likely first condensed in Ceres-like bodiesMany of the basaltic achondrites originated from a common parentbody Dawn verified that Vesta was consistent with that parentbody hence strengthening geochemical inferences from thesesamples on the formation and evolution of the solar system andsupporting hypotheses for their delivery from Vesta to Earth Cereshas not revealed itself with a meteoritic record While the surface isscarred with craters it is probable that the ejecta from the crater-forming event created little competent material from the icy crustand any such ejected projectiles that reached Earth might havedisintegrated upon entry into the Earthrsquos atmosphereCeresrsquo surface differs greatly from Vestarsquos Plastic or fluidized masswasting is apparent as are many irregularly shaped cratersincluding many polygonal crater forms There are many central-pitcraters possibly caused by volatilization of the crust in the center ofthe impact There are also many central-peak craters which weremade by rebound or pingo-like formation processes Brightdeposits dot the landscape which are possibly salt-rich suggestingfluvial activity beneath the crust Observations of the brightestspots on Ceres could suggest sublimation from the surface of thebright area which may be water vapor driven as Herschelobservations suggest Ceres is not only the most massive body inthe asteroid belt but also possibly the most active

Author(s) Christopher T RussellInstitution(s) 1 UC Los Angeles

210 ndash Pluto System21001 ndash New Horizons disk-integrated approachphotometry of Pluto and CharonApproach and cruise observations of Pluto and Charon by NASAsNew Horizons LOng Range Reconnaissance Imager (LORRI)allow monitoring of Pluto not only at phase angles beyond Earths2 degree limit but present a near constant sub-observer latitude of43 degrees However the creation of light curves and solar phasecurves of the pair prove to be an interesting challenge Early imagesof the pair from July 2013 are barely resolved and have low signalwhile later images show the pair clearly resolved and at sufficientresolution Just at the Pluto approaches the signal level and imagequality of prior HST images surface features become resolvedrendering disk integrated photometry increasingly difficult andinaccurate with the largest discrepancies found at longitudeswhich show the intersection of features informally namedTombaugh Regio (the heart) and Cthulhu Macula (the whale)

Now post flyby accurate knowledge of the radius and the shapesof surface features and their patterns of dark and light allow for thecreation of custom PSFs created from flyby maps Using thesemaps we present disk-integrated approach photometry a solarphase curve and estimate Hapke parameters taking into accountthe sub-observer positionThis work was supported by the NASA New Horizons Project

Author(s) Amanda M Zangari Marc W Buie Bonnie JBuratti Anne J Verbiscer C J A Howett H A Weaver Catherine B Olkin Kimberly Ennico Leslie A Young S ASternInstitution(s) 1 Jet Propulsion Laboratory California Inst ofTechnology 2 Johns Hopkins University Applied PhysicsLaboratory 3 NASA Ames Research Center 4 SwRI 5University of Virginia

21002 ndash On the Departure from Isothermality ofPlutos Volatile Ice due to Local Insolation andTopographyPlutorsquos atmosphere is known to be supported by the vapor pressureof ices that are volatile at low temperature primarily N andsecondarily CH and CO The atmospheric bulk is regulated by theglobally average temperature of the ice which is determined by aradiative balance between the diurnally average insolationabsorbed globally by the volatile ice and the global volatile icethermal radiation This bulk is sufficient that Plutorsquos atmosphere isclose to hydrostatic equilibrium though this may not remain so asPluto continues to move towards aphelion With the weight of theatmosphere currently distributed evenly around the body the icetemperature is expected to be globally isothermal in absence oftopographic variations due to the transport of latent heat fromregions of high insolation to low insolation through sublimationand condensation Images returned from the New Horizonsspacecraft show topographical features including mountain rangesthat extend above 35 km with albedo variations that suggest atopographical dimension or dependence of the volatile ice depositsIn general the conditions often applied to a volatile atmosphere ofhydrostatic equilibrium and vapor-solid phase equilibrium areapproximations that may not always both be appropriate This isparticularly the case in the presence of topography when theatmospheric lapse rate differs from the wet adiabat We present ourresults of an investigation of the effect of variable insolation andtopography on Plutorsquos local ice temperature assuming anatmosphere close to hydrostatic equilibrium

Author(s) Laurence M Trafton John A StansberryInstitution(s) 1 Space Telescope Science Institute 2 Univ ofTexas at Austin

21003 ndash New Horizons and Hubble Space TelescopePhotometry of Nix and HydraNew Horizons has provided the first spatially-resolved images ofPlutorsquos small satellites enabling the characterization of albedo andscattering properties across their surface Application ofphotometric models to yield the physical properties of airlessplanetary surfaces requires observations spanning the broadestpossible range of viewing and illumination geometries from fulldisk to thin crescent While New Horizons observed the Plutosystem at phase angles no smaller than 15deg full-disk Hubble SpaceTelescope images (HST Program 13367 M Buie PI) at phaseangles between 006deg and 17deg constrain the phase function nearopposition Together with New Horizons disk-resolved images weuse the near-opposition phase function to test whether ejectaexchange (Stern 2009 Icarus 199 571) affects photometricproperties With direct measurements of small satellite sizes fromNew Horizons we can determine the disk-integrated geometricalbedo by extrapolating the HST observations to zero phase NewHorizons observations at larger phase angles reveal surfaceroughness and directional scattering properties Finally we placethe photometric properties of Plutorsquos small satellites in context withthose of similar size in other planetary systems This work wassupported in part by the NASA New Horizons Project

1

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37

Author(s) Anne J Verbiscer Marc W Buie Richard PBinzel Marina Brozovic Kimberly Ennico William MGrundy Robert Jacobson Cathy B Olkin Mark R Showalter John R Spencer Sol Alan Stern Hal A Weaver Leslie AYoungInstitution(s) 1 Jet Propulsion Laboratory 2 Johns HopkinsUniversity Applied Physics Laboratory 3 Lowell Observatory 4Massachusetts Institute of Technology 5 NASA Ames ResearchCenter 6 SETI Institute 7 Southwest Research Institute 8University of Virginia

21004 ndash Long Wavelength Observations of ThermalEmission from Pluto and Charon with ALMALong wavelength observations of Pluto can determine atmospherictemperatures abundances and vertical distributions for thosemolecules that have transitions at these wavelengths In additionobservations of both Pluto and Charon can elucidate their surfaceand subsurface temperatures and surface compositions (anddistribution with enough resolution) We have used the AtacamaLarge Millimeter Array (ALMA) to observe the CO and HCN in theatmosphere of Pluto and to observe thermal emission from thetwo bodies where the resolution is enough to separate them (butnot enough to resolve each individually) We report here on thethermal emission observations and separately at this meeting onthe CO [1] and HCN [2] observations We observed thePlutoCharon system with ALMA on June 12 and 13 2015 at awavelength of ~086 mm Both days provide separate observationsof the thermal emission from Pluto and Charon We find apreliminary value of the brightness temperature of the two bodiesof 35 K and 46 K with variation of less than 1 K between the twodays and SNR of gt 300 for Pluto and gt 100 for Charon This issimilar to previous observations of the separate thermal emissionof the two bodies with the Submillimeter Array (SMA) [3] and VeryLarge Array (VLA) [4] We will discuss the implications of thesemeasured brightness temperatures and the apparent lack ofsignificant variation between the two days (longitudes)[1] Gurwell et al this meeting [2] Lellouch et al this meeting [3]Gurwell amp Butler BAAS 37 2005 [4] Butler et al BAAS 43 2010

Author(s) Bryan J Butler Mark Gurwell EmmanuelLellouch Arielle Moullet Raphael Moreno DominiqueBockelee-Morvan Nicolas Biver Thierry Fouchet Darek Lis Alan Stern Leslie Young Eliot Young Hal Weaver JeremieBoissier John StansberryInstitution(s) 1 Institut de Radio-Astronomie Millimeacutetrique 2Caltech 3 Harvard-Smithsonian Center For Astrophysics 4 JHUAPL 5 NRAO 6 Observatoire de Paris 7 STScI 8 SWRI

21005 ndash The Radii and Oblateness of Pluto andCharon Preliminary Results from the 2015 NewHorizons FlybyWe present preliminary results for the radii and oblateness of Plutoand Charon Accurate determinations of the mean radii of Plutoand Charon are important for establishing their densities and bulkcomposition A fossil bulge if present would place constraints onthe thermal and orbital evolution of these bodies [12] The NewHorizons LORRI imaging system [3] has provided global images ofPluto and Charon with best resolutions of 38 and 23 kmpixrespectively Three separate approaches have been used todetermine mean radii and oblateness from the images two using athreshold DN value [45] and one using a maximum gradientmethod These approaches were validated using synthetic imageshaving a range of photometric functions Tradeoffs between thelimb center location and the derived shape in individual images canbe reduced by combining limb pixel locations obtained fromdifferent imaged rotational phasesThis work was supported by NASAs New Horizons project[1] Robuchon amp Nimmo Icarus 216 426 2011 [2] McKinnon ampSinger DPS 46 abs no 41907 2014 [3] Cheng et al SSR 140189 2008 [4] Dermott amp Thomas Icarus 73 25 1988 [5]Thomason amp Nimmo LPSC 46 abs no 1462 2015

Author(s) Carey M Lisse Francis Nimmo William BMcKinnon Orkan M Umurhan Marc W Buie Tod R Lauer James H Roberts S Alan Stern Hal A Weaver Leslie AYoung Kimberly Ennico-Smith Cathy B OlkinInstitution(s) 1 Johns Hopkins Univ Applied Physics Lab 2NASA ARC 3 NOAO 4 SwRI 5 UCSC 6 WashingtonUniversity St Louis

21006 ndash Geomorphological Mapping of SputnikPlanum and Surrounding Terrain on PlutoThe New Horizons flyby of Pluto in July 2015 has provided the firstfew close-up images of the Kuiper belt object which reveal it tohave a highly diverse range of terrains implying a complexgeological history The highest resolution images that have yetbeen returned are seven lossy 400 mpixel frames that cover themajority of the prominent Plutonian feature informally namedSputnik Planum (all feature names are currently informal) and itssurroundings This resolution is sufficient to allow detailedgeomorphological mapping of this area to commence Losslessversions of all 15 frames that make up the mosaic will be returnedin September 2015 and the map presented at DPS will incorporatethe total area covered by these framesSputnik Planum with an area of ~650000 km is notable for itssmooth appearance and apparent total lack of impact craters at 400mpixel resolution The Planum actually displays a wide variety oftextures across its expanse which includes smooth and pittedplains to the south polygonal terrain at its center (the polygons canreach tens of kilometers in size and are bounded by troughs thatsometimes feature central ridges) and to the north darkerpolygonal terrain displaying patterns indicative of glacial flowWithin these plains there exist several well-defined outcrops of amottled lightdark unit that reach from several to tens ofkilometers across Separating Sputnik Planum from the darkcratered equatorial terrain of Cthulhu Regio on its south-westernmargin is a unit of chaotically arranged mountains (HillaryMontes) similar mountainous units exist on the south andwestern margins The northern margin is bounded by rugged hillycratered terrain (Cousteau Rupes) into which ice of SputnikPlanum appears to be intruding in places Terrain of similar reliefexists to the east but is much brighter than that to the north Thesouthernmost extent of the mosaic features a unit of roughundulating terrain (Pandemonium Dorsa) that displays very fewimpact craters at 400 mpixel resolutionThis work was supported by the NASA New Horizons project

Author(s) Oliver White Alan Stern Hal Weaver CathyOlkin Kimberly Ennico Leslie Young Jeff MooreInstitution(s) 1 NASA Ames Research Center 2 SouthwestResearch Institute 3 The Johns Hopkins University AppliedPhysics Laboratory

21007 ndash Probing Plutos Underworld Predicted IceTemperatures from Microwave RadiometryDecoupled from Surface ConditionsThe Pluto dwarf planet has been successfully observed in July 2015by the New Horizons spacecraft (NASA) during a close-targetedflyby which reavealed surprising and fascinating landscapes Whiledata are still being downlinked on the ground we propose topresent a prediction of the observation of the Radio ScienceExperiment experiment (REX) that occured on July 14 2015 andaimed at measuring the microwave brightness temperature ofPlutorsquos night sidePresent models admit a wide range of 2015 surface conditions atPluto and Charon where the atmospheric pressure may undergodramatic seasonal variation and for which measurements havebeen performed by the New Horizons mission One anticipatedobservation is the microwave brightness temperature heretoforeanticipated as indicating surface conditions relevant to surface-atmosphere equilibrium However drawing on recent experiencewith Cassini observations at Iapetus and Titan we call attention tothe large electrical skin depth of outer solar system materials suchas methane nitrogen or water ice such that this observation mayindicate temperatures averaged over depths of several or tens ofmeters beneath the surface

8 74 1 5

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Using a seasonally-forced thermal model to determine microwaveemission we predict that the southern hemisphere observations (inthe polar night in July 2015) of New Horizons should displayrelatively warm effective temperatures of about 40 K This wouldreflect the deep heat buried over the last century of summer evenif the atmospheric pressure suggests that the surface nitrogen frostpoint may be much lower We will present our predictions anddiscuss their impact for the interpretation of the REXmeasurements

Author(s) Alice Le Gall Ralph Lorenz Cedric LeyratInstitution(s) 1 APL 2 LATMOS 3 LESIA

21008 ndash The visible spectrum of Pluto secular andlongitudinal variationContinuous near-infrared spectroscopic observations during thelast 30 years enabled the characterization of the Plutos surface andthe study of its variability Nevertheless only few data are availablein the visible range where the nature of the complex-organics canbe studiedFor this reason we started an observational campaign to obtain thePlutos relative reflectance in the visible range with the aim ofcharacterizing the different components of its surface andproviding ground based observations in support of the NewHorizons mission We observed Pluto on six nights in 2014 withthe imagerspectrograph ACAMWHT (La Palma Spain) Weobtained six spectra in the 040 ndash 093 microm range that covered awhole Plutos rotational period (64 days)To study longitudinal variations we computed for all the spectrathe spectral slope and the position and the depth of the methaneice absorption bands Also to search for secular or seasonalvariations we compared our data with previously published resultsAll the spectra present a red slope indicating the presence ofcomplex organics on Plutos surface and show the methane iceabsorption bands between 073 and 090 μm We also report thedetection of the CH absorption band at 062 μm already detectedin the spectra of Makemake and Eris The measurement of theband depth at 062 μm in the new spectra of Pluto and in thespectra of Makemake and Eris permits us to estimate the Lambertcoefficient not measured yet at this wavelength at a temperatureof 30 K and 40 KWe find that all the CH bands present a blue shift This shift isminimum at the Charon-facing hemisphere where the CH is alsomore abundant indicating a higher degree of saturation of CH inthe CH N dilution at this hemisphereComparing with data in the literature we found that thelongitudinal and secular variations of the parameters measured inour spectra are in accordance with previous results and with thedistribution of the dark and bright material as showed by thePlutos albedo maps from New HorizonsIn 2015 new observations were run quasi-simultaneously with theNew Horizons flyby at 10 different Pluto longitudes (July 3 to 14) The data are currently being reduced

Author(s) Vania Lorenzi Noemiacute Pinilla-Alonso Joshua PEmery Javier Licandro Dale P Cruikshank Will Grundy Richard P BinzelInstitution(s) 1 Department of Earth amp Planetary SciencesUniversity of Tennesse 2 Fundacioacuten Galileo Galilei - INAF 3Instituto Astrofiacutesico de Canarias IAC 4 Lowell Observatory 5Massachusetts Institute of Technology 6 NASA Ames ResearchCenter

21009 ndash New rotationally resolved spectra of Pluto-Charon from 350 - 900 nmWe are using the 11-meter Southern African Large Telescope(SALT) to acquire high-resolution rotationally resolved visiblespectra of Pluto-Charon We use the Robert Stobie Spectrograph(RSS) to observe Pluto-Charon from 350 nm to 900 nm At 500nm resolution is 005 nm (R ~ 100000) and SNR per spectralresolution element is ~ 500We planned observations for 13 dates during June-September2014 and 13 more dates during June-September 2015 Theobservations for each season were spaced so as to equally sample

Plutos 65-day rotational period As of the abstract submission wehave data from 11 nights (2014) and 9 nights (2015) in hand Mostof the observations were taken with observations of solar-type starHD 146233 to determine the surface reflectivityOur results will provide constraint on the composition and spatialdistribution of material on Plutos surface enabling comparison toprevious epochs and near-infrared results and giving aground-truth for New Horizons July 2015 flyby In addition ourdata will allow us to search for new spectral features in the range350 nm to 600 nm at a sensitivity substantially higher thanpreviously published searches

Author(s) Henry B Throop Will Grundy Cathy B Olkin Leslie A Young Amanda A SickafooseInstitution(s) 1 Lowell Observatory 2 PSI 3 South AfricanAstronomical Observatory 4 Southwest Research Institute

21010 ndash Spectroscopy of Plutos Surface from 28 - 36microm during the New Horizons FlybySpectroscopy of Pluto in the 1 - 25 microm range has produced keyresults over the past two decades identification of nitrogen COmethane and ethane ices longitudinal variability in theconcentrations of these ices evidence of dissolved vs puremethane and nitrogen ices and the surface temperature andcrystalline state of nitrogen ice (eg Douteacute et al 1999 Holler etal 2014) Only a few spectra have been published at wavelengthsfrom 25 - 5 microm (eg Protopapa et al 2008 Olkin et al 2007)but these few L- and M-band spectra changed our interpretation ofPlutos surface the depth of the 33 microm methane band precludessignificant regions of pure of nitrogen ice the slope of the methaneband at 31-32 microm is sensitive to the fraction of pure methane vsmethane that is diluted in nitrogen frost and an absorption featureat 467 microm needs an identified source (but could be due to COCH3D or other constituent) The LEISA instrument on NewHorizons obtained spectra of Plutos surface at wavelengthsbetween 125 - 25 microm To complement the spacecraftinstrumentation we observed Plutos disk-integrated spectra from28 - 36 microm on two half-nights (12-JUL-2015 and 14-JUL-2015(UT)) using the NIRSPEC spectrograph at the WM KeckObservatory Conditions were excellent throughout most of theobserving run with seeing under 05 at K We will compare ourresults to observations obtained in 2001 with the same instrumentand report on evidence for surface constituents that have beenfound at shorter wavelengthsReferencesDouteacute et al Evidence for methane segregation at the surface ofPluto Icarus 142 421-444 (1999)Holler BJ et al Evidence for longitudinal variability of ethaneice on the surface of Pluto Icarus 243 104-110 (2014)

Author(s) Eliot F Young Leslie A Young Henry Roe Bryan J HollerInstitution(s) 1 Lowell Observatory 2 Southwest ResearchInst 3 University of Colorado

21011 ndash Glacial Flow on and onto Sputnik PlanumSputnik Planum (SP) is the high albedo apparently crater-freewestern portion of Tombaugh Regio imaged in July by the NewHorizons LORRI instrument The relatively high resolution (400mpix) LORRI mosaics of the northern portions of the planumbordered by the Cousteau Rupes (CR) scarp reveal surface patternshighly suggestive of viscous flow dynamics Spectroscopicmeasurements of SP taken by the New Horizons LEISA instrumentalso indicate that SP is a region containing a significant amount ofCO It has also been long known that CO and N are associatedwith one another on SP Taken together these observationssuggest the possibility that the high albedo material on SP is avolatile ice mix possibly flowing atop a bedrock-like substrate Theapparent notable lack of craters on SP strongly suggests that theflow processes act on relatively fast geologic timescales Using theknown properties of various volatile ice mixtures in thetemperature range of interest we formulate and implement anumerical landform evolution model in order to examine a numberof hypothetical evolutionary scenarios for SP and its environs This

2 1 3

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[12]

[2] 2[3-4]

39

work was supported by NASAs New Horizons project All place names on Pluto and Charon are informally known as

such as of the writing of this abstract Stern S A et al 2015Science Grundy amp Buie 2001 Icarus 153 248 Grundy et al2013 Icarus 223 710

Author(s) O M Umurhan J M Moore W B McKinnon A D Howard F Nimmo W Grundy S A Stern H Weaver C Olkin K Ennico L A YoungInstitution(s) 1 Johns Hopkins University Applied PhysicsLaboratory 2 Lowell Observatory 3 NASA-Ames ResearchCenter 4 Southwest Research Institute 5 University ofCalifornia Santa Cruz 6 University of Virginia 7 WashingtonUniversity St Louis

21012 ndash A Central Flash at an Occultation of a BrightStar by Pluto Soon Before New Horizons FlybyFrom the Mt John Observatory New Zealand we were so close tothe center of the occultation path on 29 June 2015 UTC that weobserved a modest central flash from the focusing of starlight froma 12th-magnitude star The star was one of the brightest ever in ouryears of continual monitoring that started in 2002 At the time ofPlutos perihelion in 1989 it was feared from models that Plutosatmosphere might collapse by now a motivation for the timelylaunch of New Horizons some models now allow Pluto to retain itsatmosphere throughout its orbitWe used our frame-transfer CCD at 10 Hz with GPS timing on the1-m McLellan telescope of Canterbury U We also observed with aLowell Obs infrared camera on the AAVSO 06-m OpticalCraftsman telescope and obtained 3-color photometry at a slowercadence on a second 06-m telescope We coordinated with theoverflight of SOFIA and its 25-m telescope which benefited fromlast-minute astrometry and the Auckland Observatorys and otherground-based telescopesOur light curves show a modest central flash our tentativegeometrical solution shows that we were only about 50 km fromthe occultation paths centerline The flash is from rays lower thanotherwise accessible in Plutos atmosphere Our light curves atsuch high cadence that we see spikes caused by atmospheric effectsthat we had not seen so well since our 2002 Mauna Kea occultationobservations show that Plutos atmosphere had not changeddrastically since our previous years observations Our data providea long-term context for New Horizons highly-detailed observationsof Plutos atmosphere in addition to providing a chord for thegeometrical solution that includes SOFIAs observationsOur observations were supported by NASA Planetary Astronomygrants NNX12AJ29G to Williams College NNX15AJ82G to LowellObservatory and NNX10AB27G to MIT and by the NationalResearch Foundation of South Africa We are grateful to AlanGilmore Pam Kilmartin Robert Lucas and Carolle Varughese forassistance at Mt John We thank the AAVSO for use of theAAVSOnet 06-m telescope and Arne Henden for assistance

Author(s) Jay M Pasachoff Bryce A Babcock Rebecca FDurst Christina H Seeger Stephen E Levine Amanda SBosh Amanda A Sickafoose Michael J Person Fumio Abe Daisuke Suzuki Masayuki Nagakane Paul J TristamInstitution(s) 1 Lowell Obs 2 MIT 3 Mt John U Obs 4Nagoya U 5 Notre Dame 6 Osaka U 7 Williams College

21013 ndash Placing SOFIA in the central flash for the 29June 2015 Pluto OccultationWe report on the astrometry prediction process carried out for the29 June 2015 occultation of an 119 magnitude star by Pluto Theoccultation star UCAC2 139-209445 was first identified in 2013 asa good candidate for an occultation to be observed withStratospheric Observatory for Infrared Astronomy (SOFIA) due tothe circumstances of the event In addition the events proximity tothe New Horizons encounter with Pluto made the event even moretimely We were awarded time on SOFIA for the Pluto occultationin 2014 From mid-2014 up through the night of the occultationwe tracked Plutos position We collected astrometric data fromfour telescopes the SARA-CT telescope located in Cerro TololoInternational Observatory Chile the Lowell Observatory 42-inch

Hall telescope the Lowell Observatory 43-m Discover ChannelTelescope both in Flagstaff AZ and the USNO 155-m Kaj Strandtelescope in Flagstaff AZ The objective of the astrometricobservations was to improve the prediction enough to place theaircraft within the central flash zone (approximately plusmn75 km 5masfrom the center line of the Pluto shadow)The prediction uncertainties included those of the star position andproper motion Pluto ephemeris offset potential zone-dependentoffsets in the reference catalog unknown stellar duplicity andcenter-of-mass to center-of-light offsets Over the two years sincewe identified this event as promising we worked to steadilydecrease each of the sources of uncertaintyWe communicated prediction updates to the SOFIA flight planningteam We provided a pre-take-off update which was then followedby a later in-flight update that necessitated a change in the flightplan of 320 km The crew were able to implement this change andSOFIA was able to capture the central flash of this event (Bosh etal and Person et al this conference)

Author(s) Carlos A Zuluaga Amanda S Bosh Michael JPerson Stephen E Levine Len P Bright Hugh C Harris Trudy Tilleman Thanawuth Thanathibodee Luke WWeisenbachInstitution(s) 1 Lowell Observatory 2 Massachusetts Instituteof Technology 3 US Naval Observatory

21014 ndash Constraints on Plutos Hazes from 2-ColorOccultation LightcurvesThe controversial question of aerosols in Plutos atmosphere firstarose in 1988 when features in a Pluto occultation lightcurve werealternately attributed to haze opacity (Elliot et al 1989) or athermal inversion (Eshleman 1989) A stellar occultation by Plutoin 2002 was observed from several telescopes on Mauna Kea inwavelengths ranging from R- to K-bands (Elliot et al 2003) Thisevent provided compelling evidence for haze on Pluto since themid-event baseline levels were systematically higher at longerwavelengths (as expected if there were an opacity source thatscattered more effectively at shorter wavelengths) Howeversubsequent occultations in 2007 and 2011 showed no significantdifferences between visible and IR lightcurves (Young et al 2011)The question of haze on Pluto was definitively answered by directimaging of forward-scattering aerosols by the New Horizonsspacecraft on 14-JUL-2015 We report on results of a bright stellaroccultation which we observed on 29-JUN-2015 in B- and H-bandsfrom both grazing and central sites As in 2007 and 2011 we see noevidence for wavelength-dependent extinction We will present ananalysis of haze parameters (particle sizes number density profilesand fractal aggregations) constraining models of haze distributionto those consistent with and to those ruled out by the occultationlightcurves and the New Horizons imagingReferencesElliot JL et al Plutos Atmosphere Icarus 77 148-170 (1989)Eshleman VR Plutos Atmosphere Models based on refractioninversion and vapor pressure equilibrium Icarus 80 439-443(1989)Elliot JL et al The recent expansion of Plutos atmosphereNature 424 165-168 (2003)Young EF et al Search for Plutos aerosols simultaneous IRand visible stellar occultation observations EPSC-DPS JointMeeting 2011 held 2-7 October 2011 in Nantes France (2011)

Author(s) Kara Hartig T Barry C Y Carriazo A Cole D Gault B Giles D Giles K M Hill R R Howell GHudson B Loader J A Mackie C B Olkin P Rannou JRegester A Resnick T Rodgers B Sicardy M FSkrutskie A J Verbiscer L H Wasserman C R Watson E F Young L A Young M W Buie M NelsonInstitution(s) 1 Amherst College 2 Brown University 3Greensboro Day School 4 Kuriwa Observatory 5 LowellObservatory 6 Paris Observatory 7 Pomona College 8Princeton Instruments 9 Royal Astronomical Society of NewZealand 10 Southwest Research Inst 11 Universiteacute ReimsChampagne-Ardenne 12 University of Tasmania 13 Universityof Virginia 14 University of Wyoming 15 Western SydneyAmateur Astronomy Group

[1][2]

[3] [4]

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40

21015 ndash The State of Plutos Bulk Atmosphere at theTime of the New Horizons EncounterOn 29-JUL-2015 our team - plus many critical amateurastronomers - observed a stellar occultation by Pluto from sites inAustralia and New Zealand This event was remarkable for tworeasons it preceded the New Horizons flyby of Pluto by just twoweeks and the occulted star was about 10x brighter than Plutoitself by far the brightest Pluto occultation event observed to dateThe separation of ground sites spanned nearly 900 km with respectto the central chord allowing a good geometric solution for theshadow path The lightcurves show some inflection points andbroad fangs that are characteristic of perturbations in thetemperature profile Preliminary fits show that the temperatureprofile derived from a 2006 occultation (Young et al 2008)reproduces the 29-JUN-2015 lightcurves well Assuming a surfaceradius of 1187 km for Pluto we find that the surface pressure is 18+- 3 microbar This pressure indicates that Plutos surface has not yetstarted to cool down despite a decrease in absorbed solar flux ofmore than 17 since perihelion in 1988 A surface pressure of 18microbar would correspond to a nitrogen ice surface temperature of380 KReferencesYoung EF et al Vertical Structure in Plutos Atmosphere fromthe 2006 June 12 Stellar Occultation AJ 136 1757-1769 (2008)

Author(s) Aaron C Resnick T Barry MW Buie CYCarriazo A Cole D Gault B Giles D Giles K Hartig K Hill RR Howell G Hudson B Loader J Mackie MNelson C Olkin J Register T Rodgers B Sicardy MSkrutskie A Verbiscer L Wasserman C Watson EYoung L Young A ZaluchaInstitution(s) 1 Amherst College 2 Brown University 3Greensboro Day School 4 Kuriwa Observatory 5 LowellObersvatory 6 Paris Observatory 7 Pomona College 8Princeton Instruments 9 Royal Astronomical Society of NewZealand 10 SETI 11 SwRI 12 University Of Tasmania 13University of Virginia 14 University of Wyoming 15 WesternSydney Amateur Astronomy Group

21016 ndash Predictions for the escape of CH from PlutoObservations of Plutorsquos extended atmosphere by the NewHorizonsALICE instrument have the potential to constrainmodels of energy-limited escape from planetary atmospheres Suchmodels have wide applicability ranging from dwarf planets in thesolar system to giant extrasolar planets but the opportunities totest them in actual atmospheres are limited We adapted a multi-species escape model from close-in extrasolar planets to calculatethe escape rates of CH and N from Pluto In the absence ofescape CH should overtake N as the dominant species below theexobase Theory suggests however that Plutorsquos atmosphereundergoes rapid escape that leads to a nearly constant CH mixingratio of about 1 below the exobase with CH escaping at a ratethat is only 5-10 of the N escape rate Simultaneousobservations of the N and CH profiles in the upper atmospheretogether with our model can be used to test if this is the case andinfer an estimate of the mass loss rate

Author(s) Tommi Koskinen Justin T Erwin Roger V YelleInstitution(s) 1 Lunar and Planetary Laboratory

21017 ndash Radiative equilibrium and escape of PlutosatmosphereObservations of Plutorsquos extend atmosphere by the New Horizonsspacecraft motivate an update to our modeling effort on Plutorsquosatmosphere New Horizons observations have already improvedour constraints on planet radius and surface pressure which arekey to modeling the atmospheric structure We model the radiativeconductive equilibrium in the lower atmosphere combined with theUV driven escape model of the upper atmosphere The non-LTEradiative transfer model in the lower atmosphere include heatingand cooling by CH CO and HCN The escape model of the upperatmosphere is updated to include diffusion and escape of eachmolecular component These results will be used to aid in theanalysis and better understanding of the full atmospheric

structure

Author(s) Justin Erwin Tommi T Koskinen Roger V YelleInstitution(s) 1 Lunar and Planetary Lab UA

21018 ndash Plutos atmosphere in 2015 fromhigh-resolution spectroscopyPlutos thin N2CH4 atmosphere is in vapor-pressure equilibriumwith ices on its surface The atmosphere evolves seasonally withthe varying insolation pattern on Plutos heterogenous surfaceperhaps even largely freezing out to the surface during the coldestportion of Plutos year We use high-resolution(Rasymp25000-50000) near-infrared spectroscopy to resolveatmospheric methane absorption lines from Plutos continuumspectra as well as separate Plutos atmospheric lines from thetelluric spectrum In addition to measuring the abundance andtemperature of Plutos atmospheric CH4 with broad wavelengthcoverage we are able to search for the inevitable products ofN2CH4 photochemistry In 2015 we are undertaking an intensivecampaign using NIRSPEC at Keck Observatory and IGRINS(Immersion Grating INfrared Spectrometer) at McDonaldObservatory to coincide with the New Horizons Pluto encounterWe will report initial results from this 2015 campaign and comparethe state of Plutos atmosphere at the time of the New Horizonsencounter with earlier years

Author(s) Henry G Roe Jason C Cook Gregory N Mace Bryan J Holler Leslie A Young Jacob N McLane Daniel TJaffeInstitution(s) 1 Lowell Obs 2 SwRI 3 University ofColorado Boulder 4 University of Texas at Austin

21019 ndash 12 years of Pluto surfaces evolutioninvestigated with radiative transfer modelingThe evolution of Plutorsquos surface through time due to surface -atmosphere interactions remains unknown New Horizons willprovide very high spatial resolution data of its surface state but onlyas a snapshot Furthermore this evolution during the last decadesis supposed to be fast due to the recent passage of Pluto through itsperihelion (1989) Ground based survey data over a long period oftime are thus crucial to understand the long-term evolution of thedwarf planet surfaceIRTFSpeX reflectance spectra of Pluto have been acquired during13 years (2001-2013) between 08-24 μm (Grundy et al 2013Grundy et al 2014) This set of data present the opportunity tomonitor possible changes of the surface in terms of geographicaldistribution and segregation between different chemical speciesthat are known to be present at the surface in an icy state (N CHand CO Owen et al 1993 Douteacute et al 1999) These variations arerecorded through changes in the infrared absorption bands of thedifferent ices A study based on band criteria variation (Grundy etal 2013) showed that CH absorption bands are increasingthrough time whereas N and CO absorptions bands aredecreasing (Grundy et al 2014) However quantitativeinterpretation of these data needs further investigation anddetailed radiative transfer modelingWe used the bidirectional reflectance model of Douteacute amp Schmitt(1998) to fit the IRTFSpeX spectral data This model takes intoaccount a possible stratification of chemical species aphenomenon that is likely to occur on Pluto where CH issupposed to accumulate on a sublimating molecular mixture ofN -CH -CO (Douteacute et al 1999) Different modelings take intoaccount pure CH ice a molecular mixture of N -CH -CO tholinsand water ice We modeled the grand average spectra and thenallowed the parameters to vary around the average values to modelindividual spectra and get quantitative variations of the differentspeciesPreliminary results of these modelings will be presented in terms oflongitudinal and temporal variations This study could provide auseful precursor for the analysis of the spatially resolved NewHorizon hyper spectral data acquired by the RALPHLeisainstrument

1 15 111 12 4 12 15 2

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13 13 5 711 11 10

4

4 24 2

44

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4

1 1 1

1 2 43 2 4

4

2 4

42

4

2 44 2 4

41

Author(s) Sylvain Philippe Bernard Schmitt WilliamGrundy Silvia Protopapa Cathy OlkinInstitution(s) 1 Institut de Planeacutetologie et dAstrophysique deGrenoble 2 Lowell Observatory 3 Southwest Research Institute 4 University of Maryland

21020 ndash Modeling the seasonal evolution of thesurface distribution of N2 CH4 and CO ices on Plutoto interpret New Horizons observationsThe distribution of nitrogen methane and carbon monoxide iceson Pluto as observed by New Horizons is controlled by the intenseseasonal cycle and possibly by some internal sources To betterunderstand the seasonal processes we have developed a detailedmodel of the ices cycles derived from a full Global Climate Model(GCM see Forget et al this issue) but in which the transport bythe atmosphere is parametrized based on reference GCMsimulations This allows to simulate the seasonal ices cycles onPluto for thousands of yearsThe resulting distribution primarily depends on the seasonalthermal inertia used for the different ices and is affected by theassumed topography as well As observed it is possible to formpermanent deposits in the equatorial regions with possiblelongitudinal variations depending on the topography In particularwe will discuss how the elevation of the anti-Charon point which isnot random since its location is the output of the Pluto-Charontidal locking process may explain the formation of the TombaughRegio ice deposits

Author(s) Tanguy Bertrand Franccedilois ForgetInstitution(s) 1 Laboratoire de Meacuteteacuteorologie Dynamique UPMC

21021 ndash Pluto Photochemical Models for the NewHorizons FlybyWe have designed a state-of-the-art 1-D chemistry-transport modelfor Plutorsquos atmosphere as a prelude to New Horizonsrsquo flyby on July14 2015 and as a tool with which to analyze and understand thedata gathered by the New Horizons spacecraft Prior to the closeencounter many atmospheric properties remain unknown Ourmodel demonstrates the sensitivity of hydrocarbon and HCNprofiles to the eddy mixing strength in the lower atmosphereWhen the New Horizons data arrive this model stands primed toaid the characterization of Plutorsquos atmospheric chemistry anddynamics If atmsopheric measurements have beenobtainedreleased by the time of this presentation we will show acomparison between our model and the data

Author(s) Michael L Wong Randy Gladstone Michael ESummers Yuk L YungInstitution(s) 1 California Institute of Technology 2 GeorgeMason University 3 Southwest Research Institute

21022 ndash Pluto Modeling of 3-D Atmosphere-SurfaceInteractionsAtmosphere-surface interactions on Pluto are of great importanceto creating and maintaining the atmospheric variations andheterogeneous surface that have been observed by New Horizonsand two decades prior work Publicly released imagesdata fromNew Horizons contain numerous fascinating surface features andconstrasts Insights into their origin maintenance andorevolution may be gleaned through multidisciplinary climatemodeling Some results from such modeling will be presented withan emphasis on shorter-timescale interactions

Author(s) Timothy I MichaelsInstitution(s) 1 SETI Institute

21023 ndash Mass loss from the atmosphere of PlutoMolecules can escape readily from the atmosphere of PlutoHydrodynamic escape is a process that drives large scale escapeThe process was generally believed to produce rather small isotopicfractionation Here we show that the escape highly fractionates theisotopic composition of nitrogen The process preferentially selectslighter species with an escape probability ~30 higher for the

lighter isotopologue This fractionation factor is higher than thefractionations occurring in most of known processes in modifyingthe distributions of molecules in the planetary atmospheres Thevalidity of the model can be tested against the upcoming datamainly nitrogen abundance in the outer atmosphere of Pluto fromthe New Horizons The property of the selection can significantlymodify the isotopic composition of the atmosphere leaving thepresent-day atmosphere isotopically heavier than the ancient oneThis also impacts the current view of the evolution of planetaryatmospheres Venus for example may not need that much massloss in order to explain the current DH ratio

Author(s) Mao-Chang Liang Chien-Chang Yen RonaldTaamInstitution(s) 1 Academia Sinica

21024 ndash Long-term Simulations of PlutosAtmosphere and Surface as a Coupled SystemPrevious work has modeled either Plutos atmosphere orsurfacesubsurface as separate entities In reality these tworegions should be coupled energetically and physically because ofthe accumulation sublimation and transport of volatiles (hereN2) Simulation results over multi-Pluto years are presented froma general circulation model that has both detailed atmospheric andsurfacesubsurface modules As the initial model conditions thatwill ultimately reproduce the observed surface pressures from NewHorizons stellar occultation data and spectroscopic observationsare not known by trial and error the model is initialized withdifferent surface pressures and amounts of surface ice (collectivelyknown as the volatile inventory) This ldquobrute forcerdquo method is nowa viable strategy given the ongoing development of the Plutogeneral circulation model (based on the MIT general circulationmodel dynamical core Zalucha amp Michaels 2013) and modernsupercomputing power The coupled atmosphere andsurfacesubsurface model is run until a yearly repeatable frost cycleoccurs (if at all) Surface coverage of volatiles and surface pressurewill be presented from the various scenarios Ancillary variablessuch temperature (of both the atmosphere andsurfacesubsurface) and wind direction and magnitude will also beshown for cases of particular interest

Author(s) Angela M ZaluchaInstitution(s) 1 SETI Institute

21025 ndash Extended Neutral Cloud around Plutorsquos OrbitRecent studies estimate the approximate escape rate of molecularnitrogen from Pluto as well as its ionization rate In this study wefocus on the implications of this escaping nitrogen and theresulting extended neutral cloud around Plutorsquos orbit by simulatingthe escaping nitrogen with a numerical model Several unknownparameters are varied including the dependence of Plutorsquosproduction rate on orbital distance and the distribution of speeds atwhich nitrogen is escaping Pluto

Author(s) Evan Sidrow F BagenalInstitution(s) 1 University of Colorado - Boulder

21026 ndash Pluto Near and Far PEPSSI Measurementsof Energetic Particles During the New Horizons Flybyand Investigating a Pluto Torus of CircumsolarNeutral GasThe energetic particle environment at Pluto has been unknownand little modeled until this yearrsquos historic encounter by the NewHorizon (NH) spacecraft on 14 July 2015 The first energeticparticle observations made with the Pluto Energetic ParticleSpectrometer Science Investigation (PEPSSI) instrument weredownlinked in August 2015 There are variations in the intensitiesof suprathermal (~3-30 keVnucleon) ions that are associated witha combination of the position of the spacecraft relative to Pluto thelook direction of PEPSSI and (potentially) temporal evolution inthe system We present the results of the near encounter withPluto to as close as ~116 R (1 R = 1187 km) which earlyanalysis shows include large intensity variations associated withPluto We also present the concept of a neutral gas torus

1 12 4 3

1 1

1 32 1

1

1 11

1

1 1

p p

42

surrounding the Sun aligned with Plutorsquos orbit and placeobservational constraints on it based primarily on comparison ofNH measurements with a 3-D Monte Carlo model adapted fromanalogous satellite tori surrounding Saturn and Jupiter Such atorus or perhaps partial torus could result from neutral Nescaping from Plutorsquos exosphere Unlike other more massiveplanets gaseous neutrals escape Pluto readily via Jeans escape(ie owing to the high thermal speed relative to the escapevelocity) These neutrals are not directly observable by NH butonce ionized to N or N via photolysis or charge exchange arepicked up by the solar wind ultimately reaching ~50 keV or moremaking these pickup ions detectable by PEPSSI This work wassupported by NASAs New Horizons project

Author(s) Matthew Eric Hill Peter Kollmann Ralph LMcNutt H Todd Smith Fran Bagenal Lawrence E Brown Heather A Elliott Dennis K Haggerty Mihaly Horanyi Stamatios M Krimigis Martha Kusterer Carey M Lisse David JMcComas Marcus Piquette Darrell Strobel Jamey Szalay Jon Vandegriff Eric Zirnstein Kimberly Ennico Cathy BOlkin Harold A Weaver Leslie A Young S A SternInstitution(s) 1 Johns Hopkins University 2 Johns HopkinsUniversity Applied Physics Laboratory 3 NASA Ames ResearchCenter 4 Southwest Research Institute 5 Southwest ResearchInstitute 6 University of Colorado

21027 ndash Crystalline and amorphous H O on CharonCharon the largest satellite of Pluto is a gray-colored icy worldcovered mostly in H O ice with spectral evidence for NH aspreviously reported (Cook et al 2007 Astrophys J 6631406ndash1419 Merlin et al 2010 Icarus 210 930 Cook et al 2014AASDivision for Planetary Sciences Meeting Abstracts 4640104) Images from the New Horizons spacecraft reveal asurface with terrains of widely different ages and a moderate degreeof localized coloration The presence of H O ice in its crystallineform (Brown amp Calvin 2000 Science 287 107-109 Buie amp Grundy2000 Icarus 148 324-339 Merlin et al 2010) along with NH isconsistent with a fresh surfaceThe phase of H O ice is a key tracer of variations in temperatureand physical conditions on the surface of outer Solar Systemobjects At Charonrsquos surface temperature H O is expected to beamorphous but ground-based observations (eg Merlin et al2010) show a clearly crystalline signature From laboratoryexperiments it is known that amorphous H O ice becomescrystalline at temperatures of ~130 K Other mechanisms that canchange the phase of the ice from amorphous to crystalline includemicro-meteoritic bombardment (Porter et al 2010 Icarus 208492) or resurfacing processes such as cryovolcanismNew Horizons observed Charon with the LEISA imagingspectrometer part of the Ralph instrument (Reuter DC SternSA Scherrer J et al 2008 Space Science Reviews 140 129)Making use of high spatial resolution (better than 10 kmpx) andspectral resolving power of 240 in the wavelength range 125-25microm and 560 in the range 21-225 microm we report on an analysis ofthe phase of H O ice on parts of Charonrsquos surface with a view toinvestigate the recent history and evolution of this small butintriguing objectThis work was supported by NASArsquos New Horizons project

Author(s) Cristina M Dalle Ore Dale P Cruikshank WillM Grundy Kimberly Ennico Catherine B Olkin S AlanStern Leslie A Young Harold A WeaverInstitution(s) 1 Johns Hopkins University Applied PhysicsLaboratory 2 Lowell Observatory 3 NASA Ames Reseach Center4 SETI Institute 5 Southwest Research Institute

21028 ndash Charon QuandariesRecent data from New Horizons have revealed Charon as adynamic world with an apparently young surface experiencinggeological processes Tectonic features include a chasm seen onCharonrsquos terminator and cliffs or troughs that belt the moon Thelsquomountain-in-a-moatrsquo seen in LORRI images appears emplaced in adepression also suggesting an active process These raise thequestions How hot is Charonrsquos interior Are temperatures

sufficient for liquid (ie gt 176 K the water-ammonia eutectic)How close to the surface are these temperatures reached Howthick is Charonrsquos crust We will report our calculations of thesequantitiesFollowing [12] we hypothesize that Charon formed from acircumplutonian disk after a giant impact Unlike in the lsquointactmoonrsquo scenario a Charon accreted from a disk is everywhere gt 100K and its outermost surface is gt 250 K possibly leading to fulldifferentiation into rocky core and ice mantle [2] We suggest thatcontraction of Charon due to its cooling from this hot initial state toits present-day surface temperature asymp 50 K might lead to tectonicfeatures like those seen on Mercury [3] We calculate the thermalhistory of Charon using our published codes [45] We findtemperatures today at the base of the ice mantle are cold (lt 100 K)but that ice at sufficient depth in the core should melt producingliquid It is unclear whether this liquid could reach the surface fromthe core but it may do so via processes described by [6] This wouldhave implications for cryovolcanism resurfacing and thelsquomountain-in-a-moatrsquo We will discuss the results of our modelingand our interpretation of New Horizons data at the meetingReferences [1] Canup R (2005) Science 207 546-550 [2]Desch SJ (2015) Icarus 246 37-47 [3] Byrne P Klimczak C CelalSengor AM Solomon SC Watters TR amp Hauck SA (2014) NatureGeosci 7 301-307[4] Desch SJ Cook JC Doggett TC amp PorterSB (2009) Icarus 202 694-714 [5] Neveu M Desch SJ ampCastillo-Rogez JC (2015) J Geophys Res E 120 123-154 [6]Neveu M Desch SJ Shock EL amp Glein CR (2015) Icarus 24648-64

Author(s) Steven Desch Marc NeveuInstitution(s) 1 Arizona State Univ

21029 ndash Determination of the System Mass and theIndividual Masses of the Pluto System from NewHorizons Radio TrackingOne objective of the New Horizons Radio Science Experiment REXis the determination of the system mass and the individual massesof Pluto and Charon About four weeks of two-way radio trackingcentered around the closest approach of New Horizons to the Plutosystem were processed Major problems during the processing werecaused by the small net forces of the spacecraft thruster activitywhich produce extra Δv on the spacecraft motion superposed ontothe continuously perturbed motion caused by the attracting forcesof the Pluto system The times of spacecraft thruster activity areknown but the applied Δv needs to be specifically adjusted Notwo-way tracking was available for the day of the flyby but slots ofREX one-way uplink tracking are used to cover the most importanttimes near closest approach eg during occultation entries andexits This will help to separate the individual masses of Pluto andCharon from the system mass

Author(s) Matthias Hahn Martin Paumltzold Tom Andert Michael K Bird Leonard G Tyler Ivan Linscott Dave PHinson Alan Stern Hal Weaver Cathrin Olkin LeslieYoung Kimberly EnnicoInstitution(s) 1 Department of Electrical Engineering StanfordUniversity 2 Institut fuumlr Satellitentechnik und WeltraumnutzungUniversitaumlt der Bundeswehr Muumlnchen 3 Applied PhysicsLaboratory Johns Hopkins University 4 NASA Ames ResearchCenter 5 Rheinisches Institut fuumlr Umweltforschung an derUniversitaumlt zu Koumlln Abt Planetenforschung 6 SouthwestResearch Institute

21030 ndash The Infrared Spectra and AbsorptionIntensities of Amorphous Ices Methane and CarbonDioxideOur research group is carrying out new IR measurements of icysolids relevant to the outer solar system and the interstellarmedium with an emphasis on amorphous and crystalline icesbelow ~70 K Our goal is to add to the relatively meager literatureon this subject and to provide electronic versions of state-of-the-artdata since the abundances of such molecules cannot be deducedwithout accurate reference spectra and IR band strengths In thepast year we have focused on two of the simplest and most

2

2+ +

2 22 2 6 2

5 2 62 2 2

5 6 1 62 5 3

4 2 4 4

2

2 3

2

3

2

2

2

2

4 32 3 5

5 5 1

1 1

5 5 25 1 1

1 6 3 66 4

43

abundant components of icy bodies in the solar system - methane(CH ) and carbon dioxide (CO ) Infrared spectra from sim 4500 to500 cm have been measured for each of these molecules inμm-thick films at temperatures from 10 to 70 K All knownamorphous and crystalline phases have been reproduced and forsome presented for the first time We also report measurements ofthe index of refraction at 670 nm and the mass densities for eachice phase Comparisons are made to earlier work where possibleElectronic versions of our new results are available athttpsciencegsfcnasagov691cosmicice constantshtml

Author(s) Perry A Gerakines Reggie L Hudson Mark JLoefflerInstitution(s) 1 NASA GSFC

21031 ndash Revisiting the 1988 Pluto OccultationIn 1988 Plutos atmosphere was surmised to exist because of thesurface ices that had been detected through spectroscopy but ithad not yet been directly detected in a definitive manner The keyto making such a detection was the stellar occultation methodused so successfully for the discovery of the Uranian rings in 1977(Elliot et al 1989 Millis et al 1993) and before that for studies ofthe atmospheres of other planetsOn 9 June 1988 Pluto occulted a star with its shadow falling overthe South Pacific Ocean region One team of observers recordedthis event from the Kuiper Airborne Observatory while otherteams captured the event from various locations in Australia andNew Zealand Preceding this event extensive astrometricobservations of Pluto and the star were collected in order to refinethe predictionWe will recount the investigations that led up to this importantPluto occultation discuss the unexpected atmospheric results andcompare the 1988 event to the recent 2015 event whose shadowfollowed a similar track through New Zealand and Australia

Author(s) Amanda S Bosh Edward W Dunham Leslie AYoung Steve Slivan Linda L Barba neacutee Cordella Robert LMillis Lawrence H Wasserman Ralph NyeInstitution(s) 1 Lowell Observatory 2 MIT 3 SouthwestResearch Institute 4 Wellesley College

21032 ndash Voyager IRIS Measurements of TritonsThermal Emission Impllications for PlutoThe New Horizons Pluto encounter data set includes uniqueobservations obtained using the Radio Science experiment tomeasure the night-side thermal emission at centimeterwavelengths well beyond the emission peak (in the 70 to 100micron range) 26 years ago the Voyager 2 Infrared InterferometerSpectrometer (IRIS) obtained spectra in the 30 - 50 micronwavelength range to try and detect thermal emission from Plutossibling Triton Conrath etal (1989) analyzed 16 of the IRIS spectraof Tritons dayside and derived a weak limit of 36 K - 41 K We haveanalysed those and an additional 75 spectra to refine the limits onthe temperature of Tritons surface and to explore diurnaldifferences in the thermal emission Triton results from otherVoyager instruments provide important constraints on ourinterpretation of the IRIS data as do Spitzer measurements ofPlutos thermal emissionFor unit-emissivity average temperature is 34 K inconsistent withthe pressure of Tritons atmosphere (13 - 19 microbar) thepresence of beta-phase nitrogen ice on the surface and the likelypresence ofwarm regions on the surface The atmospheric pressurerequires nitrogen ice temperatures of 374 K - 381 K which in turnrequires emissivity of 031--053 Such a low emissivity in thisspectral region might be expected if the surface is dominated bynitrogen or methane ice Averages of data subsets show evidencefor brightness temperature variations across Tritons surfaceSurprisingly the data seem to indicate that Tritons nightsideequatorial region was warmer than on the daysideThese Voyager results for Triton provide a useful context forinterpreting New Horizons and ALMA observations of emissionfrom Pluto in the sub-millimeter and centimeter region JWST willbe capable of detecting Tritons and Plutos 10 - 28 micron thermalemission although scattered light from Neptune may be an issue

for the Triton Combined with new capabilities of ALMA tomeasure the sub-millimeter emission (and even resolve the disksof Pluto and Triton) it seems possible that we may gain significantnew insights into the thermal properties of these bodies in thecoming decade

Author(s) John A Stansberry John Spencer IvanLinscottInstitution(s) 1 Southwest Research Institute 2 SpaceTelescope Science Institute 3 Stanford University

21033 ndash Exploring potential Pluto-generated neutraltoriThe NASA New Horizons mission to Pluto is providingunprecedented insight into this mysterious outer solar systembody Escaping molecular nitrogen is of particular interest andpossibly analogous to similar features observed at moons of Saturnand Jupiter Such escaping N has the potential of creatingmolecular nitrogen and N (as a result of molecular dissociation)tori or partial toroidal extended particle distributions The presenceof these features would present the first confirmation of anextended toroidal neutral feature on a planetary scale in our solarsystem While escape velocities are anticipated to be lower thanthose at Enceladus Io or even Europa particle lifetimes are muchlonger in Plutorsquos orbit because as a result of much weaker solarinteraction processes along Plutorsquos orbit (on the order of tens ofyears) Thus with a ~248 year orbit Pluto may in fact begenerating an extended toroidal feature along it orbitFor this work we modify and apply our 3-D Monte Carlo neutraltorus model (previously used at Saturn Jupiter and Mercury) tostudyanalyze the theoretical possibility and scope of potentialPluto-generated neutral tori Our model injects weighted particlesand tracks their trajectories under the influence of all gravitationalfields with interactions with other particles solar photons andPluto collisions We present anticipated N and N tori based oncurrent estimates of source characterization and environmentalconditions We also present an analysis of sensitivity to assumedinitial conditions Such results can provide insight into the Plutosystem as well as valuable interpretation of New Horizonrsquosobservational data

Author(s) Howard T Smith Matthew Hill PeterKollMann Ralph McHuttInstitution(s) 1 Johns Hopkins Applied Physics Lab

21034 ndash Visible-band (390-940nm) monitoring of thePluto absorption spectrum during the New HorizonsencounterWhilst Earth-based observations obviously cannot compete withNew Horizonsrsquo on-board instrumentation in most regards the NewHorizons data set is essentially a snapshot of Pluto in July 2015The New Horizons project team therefore coordinated a broadinternational observing campaign to provide temporal context andto take advantage of the once-in-a-lifetime opportunity to directlylink our Earth-based view of Pluto with ldquoground truthrdquo provided byin situ measurements This both adds value to existing archivaldata sets and forms the basis of long term monitoring as we watchPluto recede from the Sun over the coming years We presentvisible-band (390-940nm) monitoring of the Pluto absorptionspectrum over the period July - October 2015 from the LiverpoolTelescope (LT) In particular we wished to understand thewell-known 6-day fluctuation in the methane ice absorptionspectrum which is observable from Earth in relation to the never-before-available high resolution maps of the Pluto surface The LTis a fully robotic 20m optical telescope that automatically anddynamically schedules observations across 30+ observingprogrammes with a broad instrument suite It is ideal for bothreactive response to dynamic events (such as the fly-by) and longterm stable monitoring with timing constraints individuallyoptimised to the science requirements of each programme Forexample past studies of the observed CH4 absorption variabilityhave yielded ambiguity of whether they were caused by realphysical changes or geometric observation constraints in large partbecause of the uneven time sampling imposed by traditional

4 2‑1

1 11

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2

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44

telescope scheduling

Author(s) Robert J Smith Jonathan M MarchantInstitution(s) 1 Astrophysics Research Institute Liverpool JohnMoores University

21035 ndash Photos from Inside Pluto Historic Imagesfrom the New Horizons Encounter with PlutoNASAs New Horizons mission flew past Pluto on July 14 2015 Inthe months and weeks leading up to the encounter over 200mission personnel were located at JHU APL and directly involvedin the planning and operations of the flyby Several members of theteam were given special permission to document photographicallythis historic event These photos have been collected into a publicarchive which allows the general public to see the intimate andnormally hidden behind the scenes views of an operatingspacecraft team through times of elation times of stress publiccelebrations and private momentsWe present here a variety of these photos spanning May (thebeginning of detailed hazards searches) through the end of JulyThe entire archive will be available online and accessible to thepublicWe thank JHU-APL for arranging special permission for thephotographers (HBT CSS JS SJR DC) All photos are usedcourtesy NASASwRIJHUAPL and the individual photographers

Author(s) Henry B Throop John Spencer Stuart JRobbins Constantine Tsang Dale Cruikshank S Alan Stern Harold Weaver Peter Bedini Andrew CallowayInstitution(s) 1 JHU-APL 2 NASA Ames 3 PSI 4 SwRI

211 ndash Centaurs Trans-Neptunian Objectsand the Inner Oort Cloud21101 ndash Search for Binary TrojansWe have reexamined 41 Trojan asteroids observed with the HubbleSpace Telescope (HST) to search for unresolved binaries We haveidentified one candidate binary with a separation of 53 milliarcsecabout the width of the diffraction limited point-spread function(PSF) Sub-resolution-element detection of binaries is possiblewith HST because of the high signal-to-noise ratio of theobservations and the stability of the PSF Identification andconfirmation of binary Trojans is important because a Trojan Touris one of five possible New Frontiers missions A binary couldconstitute a potentially high value target because of theopportunity to study two objects and to test models of theprimordial nature of binaries The potential to derive mass-basedphysical information from the binary orbit could yield more cluesto the origin of Trojans

Author(s) Keith S Noll W M Grundy E L Ryan S DBenecchiInstitution(s) 1 Lowell Obs 2 NASA GSFC 3 PSI 4 U MD

21102 ndash A long term study of Centaur 174PEcheclusCentaur 174PEcheclus was discovered by the Spacewatch programon March 3 2000 and initially labelled (60558) 2000 EC 98 OnDecember 30 2005 a surprising cometary outburst was discoveredwith the 5-m Mount Palomar Observatory telescope This outburstcorresponded to a change in the overall visual magnitude fromabout 21 to about 14 At that time (60558) 2000 EC 98 was locatedat 1307 au to the Sun and was subsequently renamed with acometary designation This outburst lasted a few months and oneyear later no coma could be detected Another secondary outbursthappened in 2011 and lasted also a few months This target was atits perihelion (582 au) on April 22 2015We present new observational data obtained with the 25-m NordicOptical Telescope during the 2011 outburst and in July 2013 andwith the robotic 2-m Liverpool telescope on April 27 2014 August13 2014 and June 1 2015 We also found archive observationaldata obtained on December 22 2005These archive images point out the extremely high level of the174PEcheclus activity during the first outburst The R-magnitude

and Afrho parameter of the target were estimated to 148 and56000plusmn3000 cm respectively During the second outburst in 2011the activity level of the Centaur was lower the R-Afrho parameterswere 1200plusmn100 cm and 480plusmn70 cm in June and July respectivelyThe dust production rates needed to produce the observed comaewere approximately 700 kgs in 2005 and between 10 and 20kgs in 2011 assuming the average grain geometric albedo of 01and low outflow velocities of the dust less than 10 ms A possiblescenario of the dust coma formation for the first outburst will alsobe proposed using a Monte Carlo modelingBefore the outburst the lightcurve amplitude was 024 magnitudein the R-band with a rotation period of 2680 h (if a double-peakedlightcurve is assumed) The observational data obtained after theoutburst with the NOT do not permit to detect any clear variation inthe apparent magnitude at the level of about 01 magnitude Thedifferent possible explanations for this change will be discussed aswell as an analysis of the outbursts themselves

Author(s) Philippe Rousselot Pavlo Korsun Irina Kulyk Jean-Marc Petit Aureacutelie Guilbert-LepoutreInstitution(s) 1 Institut UTINAM 2 Main AstronomicalObservatory of NAS

21103 ndash Variability and Lightcurves Studies in theOuter Solar System Origins SurveyLightcurves provide a powerful mechanism for learning about thehistory of the collisional andor gravitational processes acting onsmall bodies since the formation and subsequent migration of oursolar nebula At the extremes they can provide constraints on thematerial properties (and interior structure) of individual objectsand perhaps in quantity can provide information about their sourcepopulations Our project consists of two datasets (1) the OuterSolar System Origins Survey (OSSOS) discovery and recoverymagnitudes and (2) observations from a 6-hour pilot study on asubset of (17) OSSOS objects using the Subaru and HyperSuprime-Cam (HSC) instrument The OSSOS objects span a fullrange of sizes from as large as several hundreds of km to as smallas a few tens of km in diameter Because of the telescope diameterand the wide field of view of HSC we are able to obtainmeasurements on multiple objects covering a range of magnitudeswith a single telescope pointing within the first two years followingobject discovery The OSSOS survey is well calibratedphotometrically and as such we use the very sparce sampling in thediscovery and recovery magnitudes to identify which objects mighthave the largest amplitude lightcruves indicating that they arelikely elongated or in potentially interesting spin states We thenselect the HSC fields containing these objects and the highestdensity of surrounding objects to obtain more densely sampledlightcurves In this way we optimize the telescope time and thepotential scientific return We will present our analysis of theOSSOS dataset and some preliminary results from HSC

Author(s) Susan D Benecchi Ying-Tung Chen MegSchwamb Shiang-Yu Wang Matthew Lehner MikeAlexandersenInstitution(s) 1 Institute of Astronomy amp Astrophysics atAcademia Sinica 2 Planetary Science Institute

21104 ndash Photometry of Scattered Disk Objects at 36μm and 45 μmScattered disk objects (SDO) are some of the most interesting of theestimated 100000 icy bodies located in the outer Solar SystemSDOs have been gravitationally disturbed and scattered by theorbital migration of Neptune The surface compositions of theseobjects provide a window into formation conditions and dynamicsof the outer Solar System Characterization of volatiles and organicmaterials in particular provide important constraints on formationconditions and subsequent surface processing of these objects Wemeasured fluxes of 36 SDOs at 36 μm and 45 μm using theInfrared Array Camera (IRAC) aboard the NASA Spitzer SpaceTelescope in order to characterize volatiles and organics on theirsurfaces Albedos calculated from these fluxes are combined withbroadband albedos from ground-based observations at shorterwavelengths (V R I J H K bands spanning 055 ndash 222 μm) to

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-1-1

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2 11 1 1

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45

provide spectrophotometry from 05 to 45 μm Much of thoseground-based data are from previously published literatureHowever we have also conducted new ground-based Y J H Kobservations of several of the targets Sizes and visible geometricalbedos which are required to convert IRAC fluxes to geometricalbedos were extracted from published literature when availableand computed from absolute magnitudes otherwise The resultingspectrophotometry of these 36 SDOs shows a wide range of surfacecompositions Several of the SDOs we observed show red visibleand near-infrared spectral slopes and strong absorptions at 36 μmand 45 μm These absorption features suggest the presence ofcomplex organics Other SDOs appear red as well but show onlymoderate absorptions at 36 μm and 45 μm Moderate absorptionfeatures at these wavelengths may indicate a mixture of H O iceand refractory material on the surface Finally some objects showno absorption at 36 and 45 μm most likely characteristic ofsilicate dust We will discuss implications of these findings in termsof surface composition and possible origins

Author(s) Chad Mellton Joshua P Emery Noemi Pinilla-Alonso Michael Mommert Cassandra Lejoly David E TrillingInstitution(s) 1 Northern Arizona University 2 University ofTennessee Knoxville

21105 ndash A Chemical and Dynamical Link Between RedCentaur Objects and the Cold Classical Kuiper BeltWe present new B-V V-R and B-R colors for 32 Centaurs objectsusing the 43-meter Discovery Channel Telescope (DCT) nearHappy Jack AZ and the 18-meter Vatican Advanced TechnologyTelescope on Mt Graham AZ Combining these new colors withour previously reported colors we now have optical broad-bandcolors for 58 Centaur objectsApplication of the non-parametric Dip Test to our previous sampleof only 26 objects showed Centaurs split into gray and red groups atthe 995 confidence level and application of the Wilcoxon RankSum Test to the same sample showed that red Centaurs have ahigher median albedo than gray Centaurs at the 99 confidencelevel (Tegler et al 2008 Solar System Beyond Neptune U ArizonaPress pp 105-114)Here we report application of the Wilcoxon Rank Sum Test to oursample of 58 Centaurs We confirm red Centaurs have a highermedian albedo than gray Centaurs at the 997 level In additionwe find that red Centaurs have a lower median inclination anglethan gray Centaurs at the 995 confidence level Because of theirred colors and lower inclination angles we suggest red Centaursoriginate in the cold classical Kuiper belt We thank the NASA SolarSystem Observations Program for its support

Author(s) Stephen C Tegler William Romanishin GuyConsolmagnoInstitution(s) 1 Northern Arizona University 2 University ofOklahona 3 Vatican Observatory

21106 ndash Constraints to the Cold Classical KBOpopulation from HST observations of faint objectsThe size distribution of the known Kuiper Belt Objects has beendescribed by a double power law with a break at R magnitude 25There are two leading interpretations to this break 1) It is theresult of the collisional evolution among these KBOs with theobjects smaller than the break being the population most affectedby collisional erosion 2) The size distribution break is primordialset during the Kuiper Belt formationThe low inclination Kuiper Belt Objects the Cold Classicalpopulation is thought to have been dynamically isolated since theformation of the Solar System and thus only collisions betweenCold Classicals would have affected their size distribution If thesize distribution is collisional it probes parameters of the KuiperBelt history strengths of the bodies impact energies andfrequency and the the number of objects If the distribution isprimordial it reveals parameters of the Kuiper Belt accretion aswell as limits on its subsequent collisional historyIn this work we obtained new HST observations of 5 faint ColdClassicals which we combine with previous HST observations toexamine the distribution of two properties of the smallest KBOs

colors and binary fraction These two properties can differentiatebetween a primordial and a collisional origin of the size distributionbreak If the smaller bodies have been through extensive collisionalevolution they will have exposed materials from their interiorswhich has not been exposed to weathering and thus should bebluer than the old surfaces of the larger bodies An independentconstraint can be derived from the fraction of binary objects theangular momentum of the observed binaries is typically too high toresult from collisions thus a collisionally-evolved populationwould have a lower binary fraction due to the easier separation ofbinaries compared to the disruption of similar-sized bodies andthe easier disruption of the binary components due to the smallersizeWe will present the constraints to the color and binary fractiondistributions we are measuring from these observations whichprobe the smallest KBOs currently observable

Author(s) Paulo F Penteado David Trilling WilliamGrundyInstitution(s) 1 Lowell Observatory 2 Northern ArizonaUniversity

21107 ndash Quantifying the Infrared Spectra of IcyMethanol - A New Investigation for Solar SystemObjectsThe presence and abundances of organic molecules inextraterrestrial settings such as on TNOs can be determined usinginfrared (IR) spectroscopy but significant challenges existAlthough reference IR spectra for organics under relevantconditions are vital for such work for many molecules the dataneeded either do not exist or exist only in fragmentary form In thispresentation we describe new laboratory results for a three-element molecule methanol (CH OH) which has been reported tobe present in planetary and interstellar ices Near- and mid-IRspectra at various ice thicknesses and temperatures are presentedband strengths are calculated and optical constants are derivedResults are compared to those of earlier workers the influence ofassumptions found in the literature is explored and possiblerevisions to the literature are described Although IR spectra ofsolid CH OH has been reported by many low-temperaturelaboratory-astrochemistry groups over the past 25 - 30 years ourwork appears to be the first that aims to determine the densitiesrefractive indices and resulting mid-IR band strengths and opticalconstants of both the amorphous and crystalline phases ofmethanol The majority of the laboratory work in this project wasdone by Tatiana Tway who was supported by a summer internshipthrough the DREAM2 program which in turn is supported by agrant from NASArsquos SSERVI program

Author(s) Reggie L Hudson Tatiana Tway PerryGerakinesInstitution(s) 1 Delaware Valley University 2 NASA GoddardSpace Flight Center

21108 ndash Trans-Neptunian Objects Transiently Stuckin Neptunes Mean Motion Resonances numericalsimulations of the current populationInferring from observational data it is well known that a largepopulation of objects orbits the Sun in mean motion resonancewith Neptune with semi-major axes in the range a=30-100AUMany of these objects were likely caught into resonances byplanetary migration---either smooth or stochastic---approximately4 billion years ago Some however scattered off Neptune andbecome transiently stuck in more recent events The goal of thisproject is to form a testable model of the transient stickingpopulation through numerical simulation We calculate the relativelikelihood of resonance sticking from the current scattering diskinto a range of resonances We confirm that transiently stuckobjects are most prevalent in n1 resonances followed by n2 n3and so on The integrated time that objects spend stuck inresonance increases for resonances with longer orbital periods Wecalculate the expected distribution of libration amplitudes forresonance angles of stuck objects and comment on implications forthe origins of distant resonance populations

2

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Author(s) Tze Yeung Mathew Yu Ruth Murray-Clay Kathryn VolkInstitution(s) 1 The University of Arizona 2 University ofCalifornia Santa Barbara

21109 ndash Dynamical Constraints on the Existence of a9th Planet Residing in the Inner Oort CloudThe discovery of Sedna a decade ago on a highly eccentric orbitbeyond the Kuiper belt challenged our understanding of the SolarSystem With a perihelion of 76 AU Sedna is well beyond the reachof the gas-giants and could not be scattered onto its highlyeccentric orbit from interactions with Neptune alone Sednarsquosaphelion at ~1000 AU is too far from the edge of the Solar Systemto feel the perturbing effects of passing stars or galactic tides in thepresent-day solar neighborhood Some other mechanism likely nolonger active in the Solar System today is required to emplaceSedna on its orbit Sednas presence predicts a population of icybodies on similar orbits residing past the Kuiper belt in what hasbeen called the Inner Oort CloudThe recent discovery of 2012 VP113 on a similar orbit to Sednaconfirmed the presence of the Inner Oort Cloud and identified apossible alignment of the argument of perihelion for objects withorbits detached from Neptune Based on the expected precessionfrequency the arguments of perihelion should be randomlydistributed The existence of a planet beyond 200 AU has beensuggested as a possible mechanism to actively control and lock theargument of perihelion of these orbits We use new dynamicalmodeling to further investigate this hypothesis and explore thepossible orbital configurations and physical properties of such abody residing beyond Neptune We will also discuss theimplications of the presence of a ninth planet for the Solar Systemsformation and for the current Inner Oort Cloud

Author(s) Megan E Schwamb Ramon Brasser Zhi-WeiZhang Institution(s) 1 Earth-Life Science Institute (ELSI) TokyoInstitute of Technology 2 Institute of Astronomy amp AstrophysicsAcademia Sinica (ASIAA)

21110 ndash Property of Kozai Dynamics of Inner OortCloud Objects with a Hypothetical Planet BeyondNeptuneThe origin of a number of Trans-Neptunian objects (TNOs) withlarge perihelion and semi-major axis are difficult to explain bycurrent models In addition to Sedna these include 2010 GB174(Chen et al 2013) and 2012 VP113 (Trujillo and Sheppard 2014)which might represent members of the Inner Oort Cloud objects(IOCOs) One thing of particular interest has to do with theclustering of the argument of perihelion (ω) of the discoveredIOCSs near 340 Trujillo and Sheppard (2014) suggested that thiseffect could be caused by the Kozai mechanism induced by adistant planet We have performed parametric studies of the orbitalmotion of hypothetical IOCOs under the influence of this distantplanet Our preliminary results indicate that this distant planet witha perihelion distance of about 150 AU if exists should have a masslarger than 2 Earth masses The observed clustering in theargument of perihelion at around 340 can not be reproduced byour simulations Instead the distribution of ω of the test particlesin the inner Oort cloud is characterized by concentration around 0

or 180 and on the other hand 90 or 270 (for smallerperihelion and lower inclination)

Author(s) Zong-Fu Sie Hsing-Wen Lin Wing-Huen IpInstitution(s) 1 Institute of AstronomyNCU

21111 ndash Deep Surveys for Inner Oort Cloud ObjectsWe are undertaking two deep wide-field surveys to discoverextremely distant solar system objects While our target solarsystem population is the Inner Oort Cloud objects such as 2012VP113 and Sedna we are also sensitive to other populations withhigh perihelia such as the Scattered Kuiper Belt Objects and thehighest perihelion Kuiper Belt Objects which have similararguments of perihelion to the Inner Oort Cloud Objects Theseunusual populations are thought to consist primarily of highly

eccentric objects which spend most of their orbits hundreds orthousands of AU from the sun Large aperture telescopes areneeded to reach the faintness limits red magnitudes of 235 to 25required for detection of even the large members of the populationIn addition wide fields of view are also needed since the skydensity of the detectable members of the populations approach 1 in100 square degrees even with large telescopesOur primary discovery instruments are the Dark Energy Camera(DECam) on the 4 meter Blanco Telescope at the Cerro TololoInter-American Observatory and Hyper Suprime-Cam (HSC) onSubaru Telescope at Maunakea Each of these instruments has atremendously wide field of view considering the size of thetelescope they are mounted on DECam has a field of view of about3 square degrees and HSC has a field of view of about 175 squaredegrees We will present our survey progress in terms of sky areacovered and new objects discovered and highlight some of ourmore interesting findings

Author(s) Chadwick A Trujillo David J Tholen Scott SSheppardInstitution(s) 1 Carnegie Inst 2 Gemini Obs 3 Univ Hawaii

21112 ndash Results from the Pan-STARRS-1 Outer SolarSystem Key ProjectAs part of the Pan-STARRS-1 Outer Solar System Key Project wehave completed two searches of the full data set obtained by thePan-STARRS-1 Science Consortium The data set spans more thanthree years and covers the full sky north of -30 degrees declinationOur two searches employ different algorithms and between themare sensitive to slow-moving objects with magnitudes brighter thanapproximately r=225 and heliocentric distances of 25-250 AU Wepresent the details of our search pipeline the results of oursurveys and plans for future surveys with the ongoingPan-STARRS-1+Pan-STARRS-2 system

Author(s) Matthew J Holman Ying-Tung Chen Hsing-Wen Lin Michael Lackner Matthew J Payne CharlesAlcockInstitution(s) 1 Harvard University 2 Harvard-SmithsonianCfA 3 IAA Academia Sinica 4 National Central University

21113 ndash The IMACS Occultation SurveyWe report the results of our extended campaign to search foroccultations of background stars by small (sub-km) Kuiper beltobjects (KBOs) using the IMACS instrument on the MagellanTelescopeWe implemented a novel shutterless continuous readout mode onthe IMACS instrument with custom-made aperture maskspermitting simultaneous high-speed (~40 Hz) photometry fornumerous stars while minimizing the effects of stellar crowdingand sky background Observing in the southern hemisphere allowsus to target the intersection of the ecliptic and galactic planeswhere hundreds of stars can be monitored with a single field ofviewWe observed for a total of ~28 hours spread over eight nightsobtaining over 10000 star-hours of light curves with per-pointSNR gt 10 This represents an order of magnitude increase in starhours compared to the previous best ground-based survey byBianco et al (2009) Our results allow us to place strongconstraints on the surface density of sub-km objects in theKuiper-Belt as well as to complement the HST FGS results ofSchlichting et al (2009 2012)

Author(s) Matthew John Payne Matthew Holman Charles Alcock David Osip Hilke SchlichtingInstitution(s) 1 Carnegie 2 Harvard-Smithsonian 3 MIT

21114 ndash The Outer Solar System Origins Survey(OSSOS) a status updateOSSOS is a 560 hour imaging survey using MegaPrime on theCFHT designed to produce a well characterized sample of Kuiperbelt objects whose orbital and physical properties will provideuseful constraints on the evolutionary history of the outer solarsystem Started in 2013 this 4 year project has now entered the

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finally year of survey operation With 12 (84 square degrees) ofthe observation fully analyzed OSOSS has detected and tracked 219TNOs brighter than our typical flux limit of r ~ 245 This is 30more detections than the entire Canada-France Ecliptic PlaneSurvey (CFEPS) a precursor projectBased on the first quarter of the survey the OSSOS project confirmsthe CFEPS-L7 orbital model of the orbital structure of the TNOpopulation (Petit et al 2011) and has provided additional evidenceof complex structure in the size distribution of scatterin TNOs(Shankman et al 2015) A number of the OSSOS science teams arepresenting results at this meeting Bannister et al Benecchi et alFraser et al Volk et al on a variety of aspects of the orbital andphysical properties the OSSOS detected samples Here we present asummary of the current status of the survey field locations basiccharacterization detection rates and some global detectionstatisticsMore details on the OSSOS project are available from our web sitewwwossos-surveyorg

Author(s) J J Kavelaars Michele T Bannister BrettGladman Jean-Marc Petit S Gwyn Ying-Tung Charles Chen Mike Alexandersen Kat VolkInstitution(s) 1 IAA Academia Sinica 2 National ResearchCouncil of Canada 3 Observatoire de Besancon 4 University ofArizona 5 University of British Columbia

21115 ndash Col-OSSOS Colours of the Outer Solar SystemOrigins SurveyThe surfaces of trans-Neptunian objects (TNOs) are poorlyunderstood Other than the large objects which exhibit signaturesof various ices very little has been discerned about thecompositions of most TNOs In recent years some concreteknowledge about the distribution of surface colours of small TNOshas come to light It is now generally accepted that small TNOs fallinto at least three classes of object based on their surface coloursand albedo TNO surface type is also correlated with dynamicalclass with certain types of TNO being found primarily in certainregions of the outer Solar System This correlation presents theintriguing idea that the surfaces of TNOs contain information onmore than composition but as well hold the key to understandingthe dynamical processes that lead to the giant planets violentlydispersing the protoplanetesimal disk and populating the KuiperBelt region It is around this idea that the Col-OSSOS survey ispredicated This 4 year program which started in 2014B issimultaneously using the Gemini-North and Canada-France-Hawaii telescopes to gather near simultaneous u g r and Jspectral photometry of all targets in the Outer Solar System OriginsSurvey (OSSOS) brighter than rrsquo=235 (~140 expected) The focusof Col-OSSOS is completeness and consistency with the sameSNR=25 being reached in all bands for all targets brighter than ourdepth limitCol-OSSOS will provide a combined compositional-dynamical mapfrom which key hypotheses about the Solar Systems cosmogonycan be tested For example by mapping the fraction of TNOs withcold-classical like surface colours we will be able to determine howmuch of the belt was populated by dynamical scattering versussweep-up from Neptune Further we will be able to constrain thecompositional homogeneity of the protoplanetesimal disk Thesurfaces of TNOs must reflect that homogeneity a heterogeneousdisk will result in a clumpy colour distribution with many uniquetypes while a homogeneous disk will result in a smoothdistribution of colours with only a few distinct types Here we willpresent preliminary results and report on the initial progress of thesurvey

Author(s) Wesley Cristopher Fraser Michele Bannister Rosemary Pike Megan Schwamb Michael Marrset JJKavelaars Susan Benecchi Audrey Delsanti Audrey Guilbert-Lepoutre Alex Parker Nuno Peixinho Peirre Vernazza Shiang-Yu WangInstitution(s) 1 CNRS - Laboratoire drsquoAstrophysique deMarseille 2 Institute of Astronomy amp Astrophysics at AcademiaSinica 3 NRC - Herzberg 4 Observatoire de Besancon 5Planetary Science Institute 6 Queens University Belfast 7Southwest Research Institute 8 University of Antofogasta 9University of Victoria

21116 ndash Status of the Transneptunian AutomatedOccultation Survey (TAOS II)The Transneptunian Automated Occultation Survey (TAOS II) willaim to detect occultations of stars by small (~1 km diameter)objects in the Kuiper Belt and beyond Such events are very rare(lt10 events per star per year) and short in duration (~200 ms)so many stars must be monitored at a high readout cadence TAOSII will operate three 13 meter telescopes at the ObservatorioAstronoacutemico Nacional at San Pedro Maacutertir in Baja CaliforniaMeacutexico With a 23 square degree field of view and a high speedcamera comprising CMOS imagers the survey will monitor 10000stars simultaneously with all three telescopes at a nominal readoutcadence of 20 Hz Construction of the site began in the fall of 2013We present here an update on the status of the TAOS II surveyincluding the site development camera fabrication and projectschedule

Author(s) Matthew J Lehner Shiang Yu Wang MauricioReyes-Ruiz You Hua Chu William Lee Zhi Wei Zhang KemH Cook Timothy Norton Andrew Szentgyorgyi CharlesAlcockInstitution(s) 1 Academia Sinica Institute of Astronomy andAstrophysics 2 Harvard-Smithsonian Center for Astrophysics 3Instituto de Astronomia Universidad Nacional Autonoma deMexico 4 Instituto de Astronomia Universidad NacionalAutonoma de Mexico

21117 ndash Pan-STARRS 1 discoveries of new NeptuneTrojans Preliminary resultsNeptune Trojans are a well-known probe of the dynamicalenvironment of the outer solar system However given the smallnumber of known Neptune Trojans many questions remain thetotal number the size distribution and the orbital distribution ofNeptune Trojans are all still unclearPan-STARRS 1 (PS1) survey provides a chance to comprehensivelyinvestigate the properties of Neptune Trojan population In thisstudy we present our preliminary results of a PS1 search for newNeptune Trojans We report several candidates At least oneunstable L5 trojan has been confirmed The preliminary orbitaldistribution of Neptune Trojan populations shows a possible L4L5distribution asymmetry from the combination of our newcandidates and the known Neptune Trojans

Author(s) Hsing-Wen Lin Yin Tung Chen Matthew JHolman Wing-Huen IpInstitution(s) 1 Harvard-Smithsonian Center for Astrophysics2 Institute of Astronomy and Astrophysics Academia Sinica 3Institute of Astronomy National Central University

212 ndash Spiraling in on Ceres and Vesta Redux21201 ndash Spikes in High-Energy Electrons at CeresEvidence for a Bow ShockStrong regular spikes in counts suggestive of electrons weremeasured by by the Dawnrsquos Gamma Ray and Neutron Detector(GRaND) when Dawn was in Survey orbit about Ceres in June2015 The source of the spikes was tentatively identified asenergetic electrons (up to 100 keV) Individual spikes lasted up toan hour and were superimposed on more gradual variationsattributed to energetic ion interactions The spikes occurred duringa period of intense solar activity associated with sunspot AR2371

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The fact that they were seen at the same location on threesuccessive orbits over a 10 day period suggests that the events areassociated with Ceres Fermi-acceleration of the solar windelectrons could explain the dramatic increase in the electroncounts If a bow shock were present at Ceres electrons could bereflected back into the solar wind and travel along the magneticfield line tangent to the shock and encounter the spacecraft If abow shock is confirmed this would have considerable implicationsfor the existence of an exosphere at Ceres its characteristics andpossible origins The observations to date allow such anatmosphere to be transitory

Author(s) Michaela Villarreal Christopher T Russell Thomas Prettyman Naoyuki Yamashita William FeldmanInstitution(s) 1 Planetary Science Institute 2 UCLA

21202 ndash Spectral modeling of Ceres VIR data fromDawn Method and ResultThe Dawn spacecraft [1] is at Ceres the closest of the IAU-defineddwarf planets to the Sun This work focuses on the interpretation ofCeresrsquo surface composition based on the data from the VIRinstrument [2] onboard Dawn The Visible InfraRed (VIR)mapping spectrometer combines high spectral and spatialresolution in the VIS (025-1mm) and IR (1-5mm) spectral rangesVIR will provide a very good coverage of the surface during itsorbital mission at CeresIn order to model the measured spectra we have utilized Hapkesradiative transfer model [3] which allows estimation of the mineralcomposition the relative abundances of the spectral end-membersand the grain size Optical constants of the spectral end-membersare approximated by applying the methodology described in [4] toIR spectra reflectance obtained from the RELAB databaseThe observed spectra of Ceres surface are affected by a thermalemission component that prevents direct comparison withlaboratory data at longer wavelengths Thus to model the wholewavelength range measured by VIR the thermal emission ismodeled together with the reflectance Calibrated spectra are firstcleaned by removing artefacts A best fit is obtained with a leastsquare optimization algorithm For further details on the methodsee reference [5]The range 25 - 29 μm is severely hindered by Earths atmospherebut it contains a strong absorption band that dominates the IRCeresrsquo spectrum Thanks to the VIR instrument we can obtain acompositional model for the whole IR range [6] We used severaldifferent combinations of materials hypothesized to berepresentative of the Ceresrsquo surface including phyllosilicates icescarbonaceous chondrites and salts The results will be discussedAcknowledgements This work is supported by the Italian SpaceAgencies and NASA Enabling contributions from the DawnInstrument Operations and Science Teams are gratefullyacknowledgedReference[1] Russell et al Space Sci Rev 163 3-23 2011[2] De Sanctis et al Space Sci Rev 163 329-369 2011[3] Hapke Cambridge Univ Press 1993 2012[4] Carli et al Icarus 235 207-219 2014[5] Raponi PhD Thesis arXiv150308172 2015[6] De Sanctis et al Nature submitted 2015

Author(s) Andrea Raponi MC De Sanctis M Ciarniello FG Carrozzo E Ammannito F Capaccioni MT Capria AFrigeri S Fonte M Giardino A Longobardo G Magni SMarchi E Palomba CM Pieters F Tosi D Turrini FZambon CA Raymond CT RussellInstitution(s) 1 Department of Earth Environmental andPlanetary Sciences Brown University 2 IAPS - INAF 3 JetPropulsion Laboratory California Institute of Technology 4University of California Los Angeles Earth Planetary and SpaceSciences

21203 ndash First Geological Mapping Investigation of theKerwan Hemisphere of Ceres (0-180degE) from NASArsquosDawn MissionThe Dawn Science team divided the surface of Ceres into

quadrangles in order to facilitate systematic geological mappingwhich is a tool used to methodically observe and interpret thesurfaces of planetary bodies Here we present a geological map ofthe Kerwan hemisphere of Ceres (0-180degE) which we assemblefrom a combination of quadrangle-scale geological maps CeresrsquoKerwan hemisphere is dominated by smooth plains whichsurround the 284-km-diameter Kerwan crater The smoothmaterial has a lower abundance of craters than other parts of theKerwan hemisphere and may suggest that regional resurfacing hasoccurred The current topography data also indicates that broadpositive topography features are present within Kerwan crater Inaddition there are ejecta deposits surrounding Haulani and Dantucraters which are distinctive in photometrically corrected mosaicsand color composite mosaics These ejecta deposits may contributeto the 1 and 2 bright albedo regions observed by Li et al (2006)with the Hubble Space Telescope In the northern region there arehomogeneously distributed impact craters most of which arecircular shallow flat-floored and contain central moundsPolygonal craters are also observed which may provide inferencesabout the target materials in which they formed In the southernregion there are numerous craters containing central mounds andsmooth material in their interiors For example the 129-km-diameter Zadeni crater contains a broad central mound Moreoverlobate deposits are found in numerous craters in the Kerwanhemisphere which are likely formed by mass wasting Ongoingwork will include the development of a detailed geological historyand the use of crater morphologies to infer the composition andphysical properties of the sub-surface Currently our geologicalmapping is based on Approach (~13 kmpixel) and Survey (~400mpixel) mosaics of clear and color filter data from the Dawnspacecraftrsquos Framing Camera In addition shape models derivedfrom Framing Camera data are used as a mapping aid Dawn willbegin the High Altitude Mapping Orbit (HAMO) in mid-Augustand our geological mapping will then incorporate the higherresolution HAMO mosaics (~140 mpixel)

Author(s) Jennifer E C Scully David A Williams Scott CMest Debra L Buczkowski Ralf Jaumann Carol ARaymond Christopher T Russell Thomas Roatsch FrankPreusker Ryan Park Andreas Natheus Martin Hoffmann Michael Schafer Thomas Platz Paul M Schenk SimoneMarchi David P OBrien Maria C De SanctisInstitution(s) 1 Arizona State University 2 German AerospaceCenter (DLR) 3 Institute of Astrophysics and Space Planetology4 Jet Propulsion Laboratory California Institute of Technology 5Lunar and Planetary Institute 6 Max Planck Institute for SolarSystem Research 7 Planetary Science Institute 8 SouthwestResearch Institute 9 The Johns Hopkins University AppliedPhysics Laboratory 10 University of California Los Angeles

21204 ndash First Geological Mapping Investigation of theOccator Hemisphere of Ceres (180deg-360degE) fromNASArsquos Dawn MissionThe Dawn Science team divided the surface of Ceres intoquadrangles in order to facilitate systematic geological mappingwhich is a tool used to methodically observe and interpret thesurfaces of planetary bodies Here we present a geological mapfrom 180deg - 360degE longitude of Ceres which we assemble from acombination of quadrangle-scale geological maps Geologic unitsare characterized based on physical attributes such as albedomorphology structure color and topography and are related togeologic processes such as volcanism tectonism impact crateringdeposition and weathering This hemisphere is dominated by aheavily cratered terrain with both fresh-looking and putatively-relaxed craters evident Also evident is Occator crater and thefeature known as Spot 5 the brightest of the ldquobright spotsrdquo onCeres Linear structures are prevalent but whether they are formeddue to impact stresses or by internal activity has not yet beendetermined However the numerous polygonal craters suggestsignificant sub-surface fracturing Color data indicates considerablecompositional diversity specifically around Spot 5 as well asaround some of the other craters and associated with some of thelinear structures Variations in crater abundance in different partsof this hemisphere suggest that some type of resurfacing might

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have occurred Domical positive relief features are present in someof the craters a 5 km high feature informally known as ldquothepyramidrdquo is also identified Determining the processes by whichthese topographically high features formed is of major interest inthis mapping effort Ongoing work will include the development ofa detailed geological history and the use of crater morphologies toinfer the composition and physical properties of the sub-surfaceCurrently our geological mapping is based on Approach (~13kmp) and Survey (~400 mp) mosaics of clear and color filter datafrom the Dawn spacecraftrsquos Framing Camera In addition shapemodels derived from Framing Camera data are used as a mappingaid Dawn will begin the High Altitude Mapping Orbit (HAMO) inmid-August and our geological mapping will then incorporate thehigher resolution HAMO mosaics (~140 mp)

Author(s) Debra Buczkowski David Williams Scott Mest Jennifer E C Scully Ralf Jaumann Chris T Russell CarolRaymond Thomas Roatsch Frank Preusker Ryan Park Andreas Nathues Martin Hoffmann Michael Schaumlfer ThomasPlatz Paul M Schenk Simone Marchi David P OBrien MCristina De SanctisInstitution(s) 1 Arizona State University 2 DLR 3 JetPropulsion Laboratory Calitfonia Institute of Technology 4Johns Hopkins University Applied Physics Laboratory 5 Lunarand Planetary Institute 6 MPI for Solar System Research 7National Institute of Astrophysics 8 Planetary Science Institute 9Southwest Research Institute 10 UCLA

21205 ndash Origin Hypotheses for Kilometer-ScaleMounds on Dwarf Planet CeresThe Dawn Framing Camera has revealed numerous domical toconical features on Ceres which may have relevance to thepresence and history of near-surface ice These features fall intotwo broad classes large domes 10s to gt100 km in diameterexhibiting 1-5 km of positive relief and small mounds lt10 km indiameter exhibiting sub-kilometer relief Here we propose threehypotheses for the origin of the ~150 small mounds identified thusfar and discuss morphological observations that could supporteach hypothesis as higher resolution data becomes availableHypothesis 1 Kilometer-scale mounds are produced by localizederuption of cryomagma or hydrothermal material Observationaltests Kilometer and sub-kilometer scale albedo variationssub-kilometer flow features on individual mounds localized ventsconical or domical shape Challenge Features are smaller thanconvective plumes expected from thermal evolution modelingHypothesis 2 Kilometer-scale mounds are analogous toterrestrial and martian pingos which grow by drawing liquid waterthrough a silicate matrix as a freezing front propagates downwardObservational tests Mounds occurring on smooth material thatfloods or embays large-scale features little or no local albedovariation no small flows associated with individual moundsdomical or ring-shape concentric or radial fractures on dome orcentral depression Challenge Small Cerean mounds observedthus far are an order of magnitude larger than terrestrial or martianpingosHypothesis 3 Kilometer-scale mounds are rootless conesanalogous to features observed on the surface of volcanic flows involatile-rich regions of Earth and Mars Rootless cones areproduced when layers of fluid material inundate a region localizeddevolatilization of a layer mobilizes clasts to form cone-shapeddeposits Observational tests Mounds on smooth material thatfloods or embays large-scale features conical not domical profilelarge central depressions cones in organized spatial patterns nosmall-scale flows Challenge Low gravity environment andorcryolava composition may be incompatible with this processIn addition to morphological observations VIR data will helpdistinguish between these hypotheses

Author(s) Hanna G Sizemore Thomas Platz Britney ESchmidt Jennifer E C Scully Christopher T Russell Scott CMest David A Crown Mark V Sykes Kynan H G Hughson Heather T Chilton David A Williams Carle M Pieters SimoneMarchi Bryan Travis Carol A RaymondInstitution(s) 1 Arizona State University 2 Brown University3 Georgia Institute of Technology 4 Jet Propulsion Laboratory 5Planetary Science Institute 6 Southwest Research Institute 7University of California Los Angeles

21206 ndash Common Mountain-Building Processes onCeres and PlutoThe Dawn Framing Camera has revealed a unique feature on thesurface of Ceres popularly referred to as the ldquopyramidrdquo It is aroughly conical and flat-topped feature with an elevation of ~5 kmand base diameter of ~20 km The side slopes are roughlyconsistent with an angle of repose one expects of particulatematerial on Earth (which may change with gravity) The pyramid isalso notable for its striations down its side over half of itscircumference These striations sharply terminate at the base of thecone without a distinctive talus deposit including an adjacentcrater Recently released images of Norgay Montes and a secondmountain chain in Tombaugh Regio on Pluto by the New Horizonsmission reveal mountains with strikingly similar morphologieswith the Ceres pyramid They are of similar size to within a factor ofa few We investigate the hypothesis that there may be a commonmechanism giving rise to these features on the two dwarf planetsGiven their significantly different heliocentric distances theremarkable ongoing widespread processing of the surface of Plutoand increasing evidence of relatively recent activity in some areas ofCeres interior processes such as plume activity or tectonics may beresponsible A comparative study of uplift morphology on the twodwarf planets may also lend insights into heat production andretention on such bodies throughout the solar system

Author(s) Mark V Sykes Michael Bland Debra LBuczkowski William Feldman Martin Hoffmann KynanHughson Ralf Jaumann Scott King Lucille LeCorre Jian-Yang Li Scott Mest Andreas Natheus David OBrien Thomas Platz Thomas Prettyman Carol Raymond VishnuReddy Ottaviano Reusch Christopher T Russell PaulSchenk Hanna Sizemore Britney Schmidt Bryan TravisInstitution(s) 1 Deutsches Zentrum fuumlr Luft- und Raumfahrt 2Georgia Institute of Technology 3 Jet Propulsion Laboratory CalTech 4 JHUAPL 5 Lunar and Planetary Institute 6 Max PlanckInstitute for Solar System Research 7 NASA GSFC 8 PlanetaryScience Institute 9 UCLA 10 USGS 11 Virginia Tech

21207 ndash The fate of Ceres original crustThe bulk density of Ceres implies that water ice comprises asubstantial fraction of Ceresrsquo interior However water ice is notstable at Ceres orbital distance and if exposed would have a lossrate of 1 km Myr or more The near-hydrostatic shape of Ceresand relatively low melting point of ice suggests that the interior is atleast partly differentiated Because Ceresrsquo surface remains exposedto space it radiates very effectively and models predictingdifferentiation retain an undifferentiated crust This would bedenser than the ice shell beneath it resulting in an unstablestratification This has led to expectations that the crust wouldfounder and the surface of Ceres might be very smooth andrelaxed But could the crust have remained to the present dayHere we model global-scale overturn on Ceres using bothanalytical two-layer linear stability analyses and numerical modelsto predict the most unstable wavelength and growth timescales forRayleigh-Taylor instabilities We find that for a 10 km-thick crustabove a 75 km-thick ice layer instabilities grow fastest at sphericalharmonic degree l=4 The growth timescale is a function of theviscosity of the upper layer This timescale is less than the age ofthe solar system unless the effective viscosity of the crust is gt 10Pa s We conclude that the crust of Ceres could remain at thesurface if it either has some finite elastic strength over a ~800 kmlength scale or is an unconsolidated regolith with a large (gt 50)macro-porosity such that the regolith is buoyant relative to waterice

4 1 83 2 10

3 2 2 36 6 6

6 5 9 87

5 53 4 7

5 5 5 73 1 2

6 5 4

8 104 8 6

9 1 11 88 8 6 86 8 3

8 7 95 8 2 8

-1

24

50

Neither end-member for the crustal strength precludes convectiveactivity in the underlying ice layer However we note that a thickporous regolith is a fantastic insulator and may promote heating ofthe interior and potential foundering of the regolith if the top of theice becomes too warm This possibility can be evaluated by modelsof thermal evolution (eg Castillo-Rogez et al 2010) An episodeof global overturn may have been preserved as spatially correlatedlong-wavelength (l=3-5) variations in albedo composition andtopography which could be measured by Dawn

Author(s) James H Roberts Andrew S RivkinInstitution(s) 1 Johns Hopkins University Applied PhysicsLaboratory

21208 ndash Post-Impact Cryovolcanism and the BrightSpots on CeresThe bright spots on Ceres recently found by NASArsquos Dawn missionhave defied easy explanation The spots are young because the 90km diameter crater in which they are found generally lackssuperposed craters but the composition is equivocal The very highalbedo contrasting on Ceresrsquo dark surface suggests ice but thespots could be salt deposits In either case formation via watervolcanism is plausible either as ice or a salty sublimate Theseobservations pose the problem How can there be recentcryovolcanic processes on a relatively low mass and density bodythat thus has a small complement of long lived radiogenic isotopes(the only plausible heat source) Here we suggest the spots are aconsequence of the impact process Ceresrsquo low bulk densityindicates abundant water ice yet spectra indicate a non-volatilesurface Various interior models predict full or partialdifferentiation which means that the near surface is structured as alargely icy layer covered by a non-volatile layer of unknownthickness For a sufficiently thick layer (gt 5-10 km) the formationof a 90 km crater will not penetrate this layer however the flowfield associated with transient crater collapse may extend into theunderlying icy material to give final crater morphologicalcharacteristics consistent with an icy surface Deposition of impactheat would primarily be in this non-volatile layer which wouldthen diffuse away including some downwards We have performedfinite element simulations of this diffusion finding that for anon-volatile layer ~10 km thick this downward diffusion can leadto supra-melting temperatures in the underlying icy material from01 to 10 Myr after the impact leading to the deposits Thisphenomenon might explain why bright spots are not abundant thecrater needs to be the right size relative to layer thickness theimpact would likely need to occur at a high strike angle (for thedeepest deposition of impact heat) and any resultant depositscould be ephemeral consistent with the craterrsquos apparent veryyoung age Additionally no special conditions are needed for theevolution of Ceres instead these bright spots result from the mostcommon geological process in the solar system impact

Author(s) Andrew J Dombard Saman Karimi Paul MSchenkInstitution(s) 1 Lunar and Planetary Institute 2 Univ ofIllinois at Chicago

21209 ndash Dawn Missionrsquos Search for satellites at CeresUpper limits on size of orbital objectsHundreds of asteroids have small secondary satellites or aredouble or even multiple body systems yet dwarf planet Ceresdoesnrsquot and isnrsquot Ground-based and space-based telescopicsearches have placed upper limits on the size of any secondarybodies gravitationally bound to Ceres of 1-2 km (Gehrels et al 1987Bieryla et al 2011) The Dawn projectrsquos satellite working groupdesigned and conducted a search during approach to Ceres andduring high orbit concentrating its search close to Ceresrsquo limbwhere previous searches could not reach Over 2000 images forboth science and optical navigation were searched In addition adedicated satellite search was conducted during two commandedoff-nadir pointings The acquired images extend 55deg x 55deg oneither side of Ceres at a range of ~ 145000 km and solar phaseangle at Ceres of 18deg No moving objects associated with Ceres weredetected The search extended down to Ceresrsquo limb (previous

searches went to 500 km above the limb) and extended the upperlimit for the non-detection to 30 +- 6 and 45 +-9 meter radius foreffective exposure times of 114s and 19s respectively An additionalsmall search was conducted using the spacecrafts star tracker fromwhich no objects were found The Dawn missionrsquos search reducedthe previous detection limit from Hubble Space Telescope imagesby two orders of magnitude Why some asteroids have satellitesand others donrsquot is a matter for dynamical speculation

Author(s) Lucy-Ann A McFadden David R Skillman Nargess Memarsadeghi Uri Carsenty Stefan E Schroeder Jian-Yang Y Li Marc D RaymanInstitution(s) 1 DLR 2 JPL 3 NASAGSFC 4 PSI

21210 ndash Physical Properties of Ceres from the DawnMissionThe physical parameters of Ceres are determined from processingthe images and radio tracking data acquired during the Approachand Survey phases of the Dawn mission The images with spatialresolution ranging from 8 km to 400 meters were processed usinga stereophotoclinometry method The radiometric tracking datawere processed through precision orbit determination togetherwith landmarks derived from the stereophotoclinometry shapereconstruction Combining the mass and volume values gives thebulk density of 2161 kgm which implies a mixture of silicateswith lighter materials Analyzing the second degree gravity fieldshows that the rotation of Ceres is very nearly about a principalaxis the degree 2 gravity field is consistent with hydrostaticequilibrium and the magnitude of J2 combined with thehydrostatic assumption implies some degree of centralcondensation

Author(s) Ryan Park Alexander Konopliv Bruce Bills Andrew Vaughan Carol Raymond Chris RussellInstitution(s) 1 Jet Propulsion Laboratory 2 UCLA

21211 ndash Ceres Evolution From ThermodynamicModeling and Telescope to Dawn OrbitalObservationsThermodynamic modeling indicated that Ceres has experiencedplanetary processes including extensive melting of its ~25 waterand differentiation (McCord and Sotin JGR 2005 Castillo andMcCord Icarus 2009) Early telescopic studies showed Ceresrsquosurface to be spectrally similar to carboneous-chondrite-likematerial ie aqueously altered silicates darkened by carbon with awater-OH-related absorption near 306 microm Later observationsimproved the spectra and suggested more specific interpretationsStructural water in clay minerals phyllosilicates perhapsammoniated iron-rich clays carbonates brucite all implyingextensive aqueous alteration perhaps in the presence of CO Telescopic observations and thermodynamic models predictedDawn would find a very different body compared to Vesta (egMcCord et al SSR 2011) as current Dawn observations areconfirming Ceresrsquo original water ice should have melted early in itsevolution with the resulting differentiation and mineralizationstrongly affecting Ceresrsquo composition size and shape over timeThe ocean should have become very salty and perhaps may still beliquid in places The surface composition from telescopes seems toreflect this complex history The mineralization with repeatedmixing of the crust with the early liquid interior and with in-fallfrom space would create a complex surface that will present aninterpretation challenge for Dawn The Dawn spacecraft iscurrently collecting observations of Ceresrsquo landforms elementaland mineralogicalmolecular composition and gravity field fromorbit Early results suggest a heavily cratered but distorted andlumpy body with features and composition consistent with internalactivity perhaps recent or current associated with water andperhaps other volatiles We will present and interpret the latestDawn Ceres findings and how they affect our earlier understandingof Ceres evolution from modeling and telescope observations

1 1

2 21

3 33 1 1

4 2

3

1 1 11 1 2

2

51

Author(s) Thomas B McCord Jean Philippe Combe JulieC Castillo-Rogez Carol A Raymond Maria Cristina De Sanctis Ralf Jaumann Eleonora Ammannito Christopher RussellInstitution(s) 1 1 Istituto di Astrofisica e Planetologia Spaziali ndashINAF 2 DLR Institute of Planetary Research 3 Jet PropulsionLaboratory 4 The Bear Fight Institute 5 University of Californiaat Los Angeles

21212 ndash Arruntia Crater A Rare Window into VestarsquosNorthern HemisphereOne of the intriguing results of the Dawn mission to Vesta was thediscovery that the only deposits containing significant olivine a keymineralogic indicator of primitive materials occur in two shallowcraters in the northern hemisphere Numerous investigations intothese exposures using either the Framing Camera (FC) or the VIRspectrometer typically find similarities between the olivineoutcropping in Belliciarsquos wall and in the Arruntia ejecta Our owninvestigations ndash using a hybrid VIR-FC approach ndashsuggest animportant distinction between the exposures at the two cratersSpecifically we find that the proximal Arruntia ejecta aredominated not by an olivine-rich component (although isolatedexamples occur) but instead by a more evolved eucriticcomponent These interspersed eucritic materials are similar toolivine-rich materials in FC data because both components pull the1 um band to longer wavelengths Ultimately however they aredistinguished by the position and strength of the 2 um band whichis not covered by FC wavelengths The Arruntia ejecta also appearolivine-like in some parameterizations of VIR spectra for the areabut closer examination of the full spectra at a fine spatial scaleclearly suggests the presence of two different materialsInterestingly the approach used here also reveals a separatediogenitic component in the distal Arruntia ejecta as well as inisolated locations within Arruntiarsquos wall Initial evaluation ofstratigraphic relationships in the Arruntia ejecta suggest apre-impact sequence of eucrite ndashgt olivine-rich -gt diogenite gradingfrom depth to the shallowest subsurface (although the small size ofArruntia means that this entire assemblage was excavated from nomore than a few of kilometers below the surface) These resultsillustrate two main points first that pyroxene-bearing materialsrich in olivine are difficult to distinguish from evolved pyroxenes inthe absence of full resolution spectroscopy at a fine spatial scaleSecond we find that Arruntia crater is likely a unique location onVesta where pervasive mechanical gardening has not yet maskedthe stratigraphic relationships between endmember diogenitic andeucritic components nor olivine-enhancements

Author(s) Jessica Sunshine Leah CheekInstitution(s) 1 University of Maryland

21213 ndash DAWN observations of Vesta versuslunar-type space weatheringThe major reason for spectral changes in lunar-type spaceweathering is production of nanophase iron (npFe ) in the lunarregolith The spectral changes include attenuation of silicateabsorption bands darkening and slope change (reddening)Spectral observations of the asteroid Vesta by DAWN missionrevealed a different pattern The darkening and the absorptionband attenuation occur in similar way as on the Moon Thereddening however is not apparent Thus is space weathering onVesta different from that we see on the MoonIn order to study effects of npFe on thereflectance spectrapyroxene (En 90) and howardite (NWA 1929) powder sampleswere subjected to the space weathering experiments Both enstatiteand howardite show progressive changes in their spectra as afunction of the increasing npFe amount An interesting feature isobserved in the comparison of the slope over the 1 and 2 microm bandsin both pyroxene and howardite While the slope over 2 microm bandshow progressive reddening with increasing npFe amount(similarly to olivine) the situation is reversed in the 1 microm bandregion The relative reduction in the spectral slope is observed inthis regionThis is due to the fact that the decrease in reflectance when addingnpFe is a nonlinear process where higher reflectance values willdecrease more than lower values If the original slope is positive as

the slope over the 1 microm band in pyroxene and howardite the slopewill flatten with increasing npFe (relative bluing)This finding can potentially explain some of the space weatheringobservations for Vesta The majority of the DAWN observationswere done in the 1 microm region where the lack of reddening isobserved similar to our pyroxene and howardite results Thus thelack of reddening over the 1 microm region as observed on Vesta doesnot contradict the space weathering mechanism driven by thepresence of npFe In order to confirm this more NIR data fromVesta are needed over the 2 microm region where our experimentspredict progressive reddening

Author(s) Tomas Kohout Ondrej Malina Antti Penttila Anni Kroger Daniel Britt Jan Fillip Karri Muinonen RadekZborilInstitution(s) 1 Department of Physics University of CentralFlorida 2 Department of Physics University of Helsinki 3Regional Centre of Advanced Technologies and MaterialsDepartments of Physical Chemistry and Experimental PhysicsPalacky University Olomouc

213 ndash Asteroid Surfaces21301 ndash Investigating Hydroxyl at Asteroid 951GaspraRecent investigations [Granahan 2011 2014] of Galileo NearInfrared Mapping Spectrometer (NIMS) observations of asteroid951 Gaspra have detected an infrared absorption feature near 28micrometers These were detected in NIMS data acquired by theGalileo spacecraft on October 29 1991 at wavelengths ranging from07 ndash 52 micrometers [Carlson et al 1992] This abstract presentsa summary of the investigation to identify the material creating the28 micrometer spectral absorption feature The current best matchfor the observed 951 Gaspra feature is the phyllosilicate boundhydroxyl signature present in a thermally desiccated QUE 99038carbonaceous chondrite as measured by Takir et al [2013]The 951 Gaspra absorption feature has been compared to a varietyof hydroxyl bearing signatures Many phyllosilicates hydroxylbearing minerals have absorption minima at different positions(27 or 285 micrometers) It also differs from similar absorptionsin a potential R chondrite analog LAP 04840 The spectra LAP04840 has a 27 micrometer feature due to biotite and a 29micrometer feature due to adsorbed water [Klima et al 2007] 28micrometer absorption minima have been found for adsorbedhydroxyl on the Moon [McCord et al 2011] and variouscarbonaceous chondrites [Calvin and King 1997 Takir et al2013] The best match with a minimum Euclidean distancedifference to the 951 Gaspra feature is found in the spectrum ofQUE 99038 [Takir et al 2013] This spectrum is the product of aninfrared measurement of a sample that had its adsorbed waterbaked off and removed in a vacuum chamber The remaininghydroxyl in the sample belongs to a mixture of phyllosilicatesdominated by the presence of cronstedtiteReferences Calvin W M and T V King (1997) Met Planet Sci32 693-702 Carlson R W et al (1992) Bull American AstroSoc 24 932 Granahan J C (2011) Icarus 213 265-272Granahan J C (2014) 45th LPSC 1092 Klima R C et al(2007) 38th LPSC 1710 McCord T B et al (2011) JGR 116E00G05 Takir D et al (2013) Met Planet Sci 48 1618ndash1637

Author(s) James C GranahanInstitution(s) 1 Leidos

21302 ndash Potentially hazardous asteroid (214869) 2007PA8 The missing link between H chondrites and theouter asteroid beltWe report near-infrared spectra (07-255 μm) of potentiallyhazardous asteroid (PHA) (214869) 2007 PA8 obtained with theNASA Infrared Telescope Facility during its close approach to Earthon November 2012 A detailed mineralogical analysis of this objectwas performed using the measured band parameters along withlaboratory spectral calibrations We found that 2007 PA8 is aQ-type asteroid with an H chondrite-like composition The olivine-

4 43 3 1

2 5 5

1 1

0

0

0

0

0

0

0

2 3 22 1 3 2

3

1

52

pyroxene abundance ratio was estimated to be 47 Wedetermined that the olivine and pyroxene chemistries of thisasteroid are Fa (Fo ) and Fs respectively The low olivineabundance and the location of the band parameters close to theH4 and H5 chondrites suggest that this object originated in theupper middle layers of a larger body that experienced certain degreeof thermal metamorphism The orbit of 2007 PA8 places the sourceregion of this asteroid in the outer part of the main belt Due to itsproximity to the J52 resonance low orbital inclination andcompositional affinity we determined that 2007 PA8 originated inthe Koronis family

Author(s) Juan Andres Sanchez Vishnu Reddy MelissaDykhuis Sean Lindsay Lucille Le CorreInstitution(s) 1 Atmospheric Oceanic and Planetary PhysicsUniversity of Oxford 2 Lunar and Planetary LaboratoryUniversity of Arizona 3 Planetary Science Institute

21303 ndash The Shape of Near-Earth Asteroid 275677(2000 RS11) From Inversion of Arecibo and GoldstoneRadar ImagesWe observed near-Earth asteroid 2000 RS11 with the Arecibo andGoldstone planetary radars during a 0035 au approach in March2014 obtaining delay-Doppler images between March 13 andMarch 17 The finest-resolution images have range resolution of75 mpixel and show that RS11 is a contact binary with complextopography We used the SHAPE software package (Magri et alIcarus 186 156ndash160 2007) to create a physical model of RS11 andits spin state from these delay-Doppler imagesThe rotation period of RS11 is well constrained from opticallightcurves P = 4444 plusmn 0001 h (Warner et al Minor PlanetBulletin 41 160 2014 and Benishek Minor Planet Bulletin 41 2572014) We found two possible pole directions and correspondingshape models mirror images of one another which provide equallygood fits to the radar data RS11rsquos pole direction is either (λ β) =(155deg 30deg) plusmn 10deg or (335deg -30deg) plusmn 10deg in J2000 eclipticcoordinates The most likely pole directions of RS11 are not alignedwith the heliocentric orbit normal and instead have an obliquitywithin 10deg of 56deg or 124degOur best-fit shape models are 1400-vertex polyhedra comprisingtwo lobes in contact The lengths of RS11rsquos principal axes are 698 plusmn71 m 578 plusmn 59 m and 758 plusmn 77 m RS11 has a volume of 0086 plusmn0026 km^3 The long axis of RS11rsquos larger lobe is 751 plusmn 77 m andthe long axis of the smaller lobe is 398 plusmn 41 m the volume ratiobetween these lobes is roughly 27 plusmn 10 Spectral data informs usthat RS11 is an S-class object (Lazzarin et al Icarus 169 3792004)RS11s shape is unusual compared with those of other contactbinary NEAs imaged by radar Its larger lobe is flattenedAdditionally while the neck between the smaller and larger lobes ofmost contact binaries is located near the larger lobes longestprincipal axis (such as in the cases of 25143 Itokawa and 4179Toutatis) RS11s neck is near its larger lobes shortest principalaxis RS11 is the first asteroid of this type for which we have a shapemodel

Author(s) Kaley Brauer Michael W Busch Lance AMBenner Marina Brozovic Ellen S Howell Michael C Nolan Alessondra Springmann Jon D Giorgini Patrick A Taylor Joseph S JaoInstitution(s) 1 Arecibo Observatory 2 Brown University 3Jet Propulsion Laboratory California Institute of Technology 4Lunar amp Planetary Laboratory University of Arizona 5 SETIInstitute

21304 ndash Thermophysical Model of S-complex NEAs1627 IvarWe present updates to the thermophysical model of asteroid 1627Ivar Ivar is an Amor class near Earth asteroid (NEA) with ataxonomic type of Sqw [1] and a rotation rate of 4795162 plusmn 54 10 hours [2] In 2013 our group observed Ivar in radar in CCDlightcurves and in the near-IRrsquos reflected and thermal regimes (08ndash 41 microm) using the Arecibo Observatoryrsquos 2380 MHz radar thePalmer Divide Stationrsquos 035m telescope and the SpeX instrument

at the NASA IRTF respectively Using these radar and lightcurvedata we generated a detailed shape model of Ivar using thesoftware SHAPE [34] Our shape model reveals more surfacedetail compared to earlier models [5] and we found Ivar to be anelongated asteroid with the maximum extended length along thethree body-fixed coordinates being 12 x 1176 x 6 km For ourthermophysical modeling we have used SHERMAN [67] withinput parameters such as the asteroidrsquos IR emissivity opticalscattering law and thermal inertia in order to complete thermalcomputations based on our shape model and the known spin stateWe then create synthetic near-IR spectra that can be compared toour observed spectra which cover a wide range of Ivarrsquos rotationallongitudes and viewing geometries As has been noted [68] theuse of an accurate shape model is often crucial for correctlyinterpreting multi-epoch thermal emission observations We willpresent what SHERMAN has let us determine about the reflectivethermal and surface properties for Ivar that best reproduce ourspectra From our derived best-fit thermal parameters we will learnmore about the regolith surface properties and heterogeneity ofIvar and how those properties compare to those of other S-complexasteroids References [1] DeMeo et al 2009 Icarus 202 160-180[2] Crowell J et al 2015 LPSC 46 [3] Magri C et al 2007 Icarus186 152-177 [4] Crowell J et al 2014 AASDPS 46 [5]Kaasalainen M et al 2004 Icarus 167 178-196 [6] Crowell J etal 2015 TherMoPS II [7] Howell E et al 2012 AASDPS 44 [8]Howell E et al 2015 TherMoPS II This work is partiallysupported by NSF (AST-1109855) NASA (NNX13AQ46G) CLASS(NNA14AB05A) and USRA (06810-05)

Author(s) Jenna L Crowell Ellen S Howell ChristopherMagri Yan R Fernandez Sean E Marshall Brian D Warner Ronald J VervackInstitution(s) 1 Center for Solar System Studies - Palmer DivideStation 2 Cornell University 3 LPLUniversity of Arizona 4The Johns Hopkins University Applied Physics Laboratory 5University of Central Florida 6 University of Maine atFarmington

21305 ndash Using Simple Shapes to Constrain AsteroidThermal InertiaWith the use of remote thermal infrared observations and athermophysical model (TPM) the thermal inertia of an asteroidsurface can be determined The thermal inertia in turn can beused to infer physical properties of the surface specifically toestimate the average regolith grain size Since asteroids are oftennon-spherical techniques for incorporating modeled(non-spherical) shapes into calculating thermal inertia have beenestablished However using a sphere as input for TPM is beneficialin reducing running time and shape models are not generallyavailable for all (or most) objects that are observed in thethermal-IR This is particularly true as the pace of infraredobservations has recently dramatically increased notably due tothe WISE mission while the time to acquire sufficient light curvesfor accurate shape inversion remains relatively long Here weinvestigate the accuracy of using both a spherical and ellipsoidalTPM with infrared observations obtained at pre- andpost-opposition (hereafter multi-epoch) geometries to constrainthe thermal inertias of a large number of asteroidsWe test whether using multi-epoch observations combined with aspherical and ellipsoidal shape TPM can constrain the thermalinertia of an object without a priori knowledge of its shape or spinstate The effectiveness of this technique is tested for 16 objectswith shape models from DAMIT and WISE multi-epochobservations For each object the shape model is used as input forthe TPM to generate synthetic fluxes for different values of thermalinertia The input spherical and ellipsoidal shapes are then steppedthrough different spin vectors as the TPM is used to generatebest-fit thermal inertia and diameter to the synthetically generatedfluxes allowing for a direct test of the approachrsquos effectiveness Wewill discuss whether the precision of the thermal inertia constraintsfrom the spherical TPM analysis of multi- epoch observations iscomparable to works that use non-spherical shapes The findingspresented at the conference will be discussed in relation to worksthat also use different shape models (ie sphere lightcurve andradar-derived shapes) to perform TPM analyses on asteroid

18 82 16

3 32 1 3

2 53 3 4 4

4 3 13

-6

5 36 5 2 1

4

53

thermal data

Author(s) Eric M MacLennan Joshua P EmeryInstitution(s) 1 The University of Tennessee

21306 ndash Near-Infrared Spectroscopy of TrojanAsteroids Assessing Compositional Bimodality atSmall SizesThe Trojan asteroids orbit the sun within Jupiterrsquos gravitationallystable Lagrange points (L4 and L5) Their unique orbits make themprime targets for study by which to further our understanding ofthe evolution of the Solar System The formation scenario that bestfits their orbital properties comes from the Nice model whichpredicts that the Trojan asteroids originally formed in the KuiperBelt and were trapped in Jupiterrsquos Lagrange regions during theperiod of giant-planet-migration-induced instability Compositionsof Trojans offer a test of this prediction Although the featurelessspectra observed previously in the near-infrared (NIR 07ndash25 μm)preclude compositional determination further analysis of thespectral slopes for these data revealed two distinct spectral groupsThe bimodality of Trojans is defined by the degree of spectralreddening in which two-thirds of Trojans exhibit redder spectrawith the remaining one-third exhibiting less-red spectra PreviousNIR observations of the Trojan asteroids to assess compositionalgroups focused on the largest objects Those observations includedall Trojans with diameter (gt75 km but an incomplete census atsmaller sizes) This study aims to determine whether thebimodality observed in large Trojans is also present for smallTrojans (lt75 km) We have observed 17 small Trojans residingwithin Jupiterrsquos L5 Lagrange point (ranging in diameter from ~ 39km to ~ 75 km) using the SpeX spectrograph at NASArsquos InfraredTelescope Facility We have reduced these data and extracted theircorresponding spectra We will analyze the spectral slopes of theseobjects in the context of previous results on Trojan spectral groupsSuch analysis will help further our understanding of the origins ofTrojan asteroids from where they may have originated andpossibly provide a unique perspective into the evolution of theSolar System

Author(s) Nicholas C Stamper Joshua P Emery MichaelP Lucas Richard J CartwrightInstitution(s) 1 University of Tennessee

21307 ndash Explaining Space-Weathering Effects onUV-Vis-NIR Spectra with Light-Scattering MethodsSpace-weathering (SW) introduces changes to the asteroidreflectance spectra In silicate minerals SW is known to darken thespectra and reduce the silicate absorption band depths In olivinethe neutral slope in Vis and NIR wavelengths is becoming positive[1] In pyroxene the positive slope over the 1 microm absorption bandis decreasing and the negative slope over the 2 microm band isincreasing towards positive values with increasing SW [2]The SW process generates small nanophase iron (npFe )inclusions in the surface layers of mineral grains The inclusionsare some tens of nm in size This mechanism has been linked to theMoon and to a certain extent also to the silicate-rich S-complexasteroidsWe offer two simple explanations from light-scattering theory toexplain the SW effects on the spectral slope First the npFe willintroduce a posititive general slope (reddening) to the spectra ThenpFe inclusions (~10 nm) are in the Rayleigh domain with thewavelength λ in the UV-Vis-NIR range Their absorption cross-section follows approximately the 1λ-relation from the Rayleightheory Absorption is more efficient in the UV than in the NIRwavelengths therefore the spectra are reddeningSecond the effect of npFe absorption is more efficient fororiginally brighter reflectance values Explanation combines theeffective medium theory and the exponential attenuation in themedium When adding a small amount of highly absorbing npFe the effective absorption coefficient k will increase approximatelythe same Δk for the typical values of silicates This change willincrease more effectively the exponential attenuation if the originalk was very small and thus the reflectance high Therefore bothpositive and negative spectral slopes will approach zero with SW

We conclude that the SW will introduce a general reddening andneutralize local slopes This is verified using the SIRIS code [3]which combines geometric optics with small internal diffusescatterers in the radiative transfer domain[1] Kohout T et al (2014) Icarus 237(15) 75ndash83[2] Kohout T et al (2015) Workshop on Space Weathering ofAirless Bodies Abstract[3] Muinonen K et al (2009) JQSRT 110 1628ndash1639

Author(s) Antti Penttilauml Timo Vaumlisaumlnen JuliaMartikainen Tomas Kohout Karri MuinonenInstitution(s) 1 University of Helsinki

21308 ndash Comparing the Data-reduction Methods forPhotometric ModelingPhotometric models describe the light scattering properties of theasteroidrsquos surface providing clues for the physical properties of thesurface and photometric correction for comparisons betweendifferent area on asteroids and laboratory measurements Differenttechniques have been widely used to reduce the photometric datafor modeling purposes including different sampling methods suchas average of each image or keep only four-corners or center areaof each image The purpose of this work is to compare thesetechniques analyzing their different effect on photometricmodeling and photometric corrections to spectrophotometric dataOur goal is to identify which data-reduction method is the bestapproach to retrieve the true photometric properties of planetarysurface and generate the most credible photometric correctionsUsing a set of image data from the Near Earth Asteroid Rendezvous(NEAR) Spacecraftrsquos Multi-Spectral Imager (MSI) we find that thedifferent approaches produce similar results but they tend toperform differently when the data set is with different quality

Author(s) Xiaoduan Zou Jian-Yang Li Beth Ellen ClarkInstitution(s) 1 Ithaca College 2 Planetary Science Institute

21309 ndash Shape and topography corrections forplanetary nuclear spectroscopyThe elemental composition of planetary surfaces can bedetermined using gamma ray and neutron spectroscopy Mostplanetary bodies for which nuclear spectroscopy data have beenacquired are round and simple analytic corrections formeasurement geometry can be applied however recentmeasurements of the irregular asteroid 4 Vesta by Dawn requiredmore detailed corrections using a shape model (Prettyman et alScience 2012) In addition subtle artifacts of topography have beenobserved in low altitude measurements of lunar craters withpotential implications for polar hydrogen content (Eke et al JGR2015) To explore shape and topography effects we have updatedthe general-purpose Monte Carlo radiation transport code MCNPXto include a polygonal shape model (Prettyman and HendricksLPSC 2015) The shape model is fully integrated with the codersquos 3Dcombinatorial geometry modules A voxel-based accelerationalgorithm enables fast ray-intersection calculations needed forMonte Carlo As modified MCNPX can model neutron and gammaray transport within natural surfaces using global andor regionalshapetopography data (eg from photogrammetry and laseraltimetry) We are using MCNPX to explore the effect ofsmall-scale roughness regional- and global-topography forasteroids comets and close-up measurements of high-relieffeatures on larger bodies such as the lunar surface MCNPX cancharacterize basic effects on measurements by an orbitingspectrometer such as 1) the angular distribution of emittedparticles 2) shielding of galactic cosmic rays by surrounding terrainand 3) re-entrant scattering In some cases re-entrant scatteringcan be ignored leading to a fast ray-tracing model that treats effects1 and 2 The algorithm is applied to forward modeling and spatialdeconvolution of epithermal neutron data acquired at VestaAnalyses of shapetopography effects and correction strategies arepresented for Vesta selected small bodies and cratered planetarysurfaces

Author(s) Thomas H Prettyman John S HendricksInstitution(s) 1 Planetary Science Institute 2 Techsource Inc

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54

21310 ndash Spectral bluing on 101955 Bennu andimplications for dynamics of sub micron regolithgrains on asteroidsC and B class asteroids (including 101955 Bennu the destination ofthe OSIRIS REx mission) display spectral bluing in the visible(Lantz et al 2013) This spectral bluing effect has been found to betemporally variable on Bennu (Binzel et al 2015) Binzel et alsuggested this is due to a fining of the ~45 micron grain sizefraction which causes spectral reddening This finer grain size ofthe ~45 micron fraction may be associated with regolith migrationduring formation of Bennus equatorial ridgeIn Brown (2014) the effect of grain size and optical index on thealbedo of small conservative and absorbing particles as a functionof wavelength was examined The conditions necessary formaximization of spectral bluing effects in real-world situationswere identifiedThe spectral bluing to be discussed in this presentation was presentin the Lantz et al spectra but not the Binzel et al spectrasuggesting that in addition to finer grain ~45 micron material adecrease in the sub micron grain sized fraction has taken place asBennus sub-Earth latitude changed between these observationsObservations of this effect may provide the strongest test yet forcohesive regolith models (eg Rositis et al 2014)In this presentation I will discuss 1) the evidence for spectralbluing on 101955 Bennu (in particular) and other bodies in oursolar system and 2) the implications of how the OVIRS instrumenton OSIRIS-REx may be used to determine the spatial variability ofthis spectral feature on Bennu and 3) the potential for OVIRS toaugment our understanding of the dynamics of sub micronmaterial on asteroidsRefsBinzel R P et al Spectral slope variations for OSIRIS-REx targetAsteroid (101955) Bennu Possible evidence for a fine-grainedregolith equatorial ridge Icarus 256 (2015) 22-29Brown Adrian J ldquoSpectral Bluing Induced by Small Particles underthe Mie and Rayleigh Regimesrdquo Icarus 239 (2014) 85ndash95Lantz C et al ldquoEvidence for the Effects of Space WeatheringSpectral Signatures on Low Albedo Asteroidsrdquo AampA 554 (2013)138Rositis B et al Cohesive forces prevent the rotational breakup ofrubble-pile asteroid (29075) 1950 DA Nature (2014) 174-176

Author(s) Adrian J BrownInstitution(s) 1 SETI Institute

21311 ndash SHERMAN A Shape-based ThermophysicalModel for Near-Earth AsteroidsWe have developed a thermophysical model SHERMAN whichcan produce temperature distributions and thermal fluxes forairless bodies Although intended for near-Earth asteroids (NEAs)it has applications to the Moon and may be adapted for othersituations SHERMAN is based on the asteroid shape modelingcode developed by Hudson (1993) and enhanced by Magri et al(2007 2011) The input model asteroid can have an arbitrary shapedescribed as a polyhedral solid with triangular facets The userspecifies a spin state which can include non-principal axis rotationThe asteroid orbit and positions of the Sun and Earth are input sothat the proper heating and viewing geometry of the object areused The user specifies the optical scattering law IR emissivitythermal inertia specific heat density and conductivity all of whichare permitted to vary across the surface if desired We have appliedthis model to relative reflectance observations of NEAs with a widerange of compositions sizes and shapes in order to determine howmuch these properties can affect the thermal emission We haveselected objects that are also observed with radar so that the shapeand spin state is known at least to some extent We find thatirregular shapes can significantly affect the surface temperaturedistribution Observations at several different viewing geometriescan rarely be fit by a single set of thermal parameters unless thedetailed shape spin and surface properties are included Wepresent results using this model and discuss future applications tobetter understand the nature of asteroid surfaces

Author(s) Ellen S Howell Christopher Magri Ronald JVervack Yanga R Fernandez Michael C Nolan Patrick ATaylor Sean E Marshall Jenna L CrowellInstitution(s) 1 Arecibo ObservatoryUSRA 2 CornellUniversity 3 JHUAPL 4 LPLU Arizona 5 U Central Florida6 U Maine at Farmington

21312 ndash Spectrophotometric Properties of GasprarsquosSurfaceUsing the shape-model derived for Gaspra [1] we calculate the localincidence emission and phase angles on a pixel-by-pixel basis forthe color image sets (164 mpx spatial resolution) acquired by theGalileo Solid State Imager (SSI) [2] Using these geometric valueswe derive a disk-resolved photometric correction for application tothe to the spectral data set for more accurate regional examinationof mineralogy and weathering across the surface We use regionalvariations in color ratios of Gasprarsquos surface to examine the degreeof space weathering incurred upon the surface and find subtlevariations across its surface Using mixing modeling methods thataccount for submicroscopic components we examine evidence forspace weathering variations correlated to composition and grainsize We note evidence of a young surface with only moderatemodification by space weathering processes SSI radiometrically-calibrated data combined with shape-model derived incidenceemission and phase angle backplanes have been archived in thePlanetary Data System for broader use by the community [3 4][1] P Thomas et al 1994 Icarus 107 23 ndash 36 [2] M Belton et al1992 Science 257 1647 ndash 1652 [3] D Domingue 2015 GalileoSSIGaspra Radiometrically Calibrated Images V10 NASA PDS[4] D Domingue 2015 Galileo SSIGaspra Color and GeometryImage Cubes V10 NASA PDS submitted

Author(s) Deborah L Domingue Faith Vilas KarenStockstill-Cahill Joshua Cahill Amanda HendrixInstitution(s) 1 Johns Hopkins UniversityApplied PhysicsLaboratory 2 Planetary Science Institute

21313 ndash Methodology of Space Weathering Simulationand Its Application on Olivine and Pyroxene SamplesHere we reported a two-step thermal treatment method [1] for thespace weathering simulation and the differences in the formationof metallic iron nanoparticles (npFe ) on the surface of olivine andpyroxene samples are discussedIn general the main goal is in controlled size of npFe formed onthe surface of olivine and pyroxene and in quantification of therelated spectral changes The transmission electron microscopy(TEM) after double-heating method revealed two significantfeatures First different sizes and concentration of npFe areobserved and secondly due to more resistance of pyroxene (eg[2]) higher temperatures are needed to produce the same amountof npFe as in the olivine case [1]Results from TEM are fully consistent with reflectance spectrawhich show progressive changes as a function of the increasingnpFe amount The reason for the observed differences inreflectance spectra can be found in the crystal structure and localenvironment at each crystallographic position of both samples It isvery similar as in the case of laser heating experiments (eg [2])where the surface of orthopyroxene is significantly more resistantto reduction than olivine due to mobility of oxygen and cationdiffusions from the bulk to surface of the samplesReferences[1] Kohout T et al (2014) Icarus 237 75-83[2] Quadery A et al (2015) JGR-Planets 120 1-19

Author(s) Ondrej Malina Tomas Kohout Jiri Tucek JanFilip Daniel Britt Radek ZborilInstitution(s) 1 Department of Physics University of CentralFlorida 2 Palacky University 3 University of HelsinkyDepartment of Physics

21314 ndash Visible Wavelength Reflectance Spectra andTaxonomies of Near-Earth Objects from Apache PointObservatoryNear-Earth Objects (NEOs) are interesting to scientists and the

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1 2 5

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0

0

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55

general public for diverse reasons their impacts pose a threat to lifeand property they present important albeit biased records of theformation and evolution of the Solar System and their materialsmay provide in situ resources for future space exploration andhabitationIn January 2015 we began a program of NEO astrometric follow-upand physical characterization using a 17 share of time on theAstrophysical Research Consortium (ARC) 35-meter telescope atApache Point Observatory (APO) Our 500 hours of annualobserving time are split into frequent short astrometric runs (seeposter by K A Nault et al) and half-night runs devoted to physicalcharacterization (see poster by M J Brucker et al for preliminaryrotational lightcurve results) NEO surface compositions areinvestigated with 036-10 μm reflectance spectroscopy using theDual Imaging Spectrograph (DIS) instrument As of August 252015 including testing runs during fourth quarter 2014 we haveobtained reflectance spectra of 68 unique NEOs ranging indiameter from approximately 5m to 8kmIn addition to investigating the compositions of individual NEOs toinform impact hazard and space resource evaluations we mayexamine the distribution of taxonomic types and potential trendswith other physical and orbital properties For example theYarkovsky effect which is dependent on asteroid shape massrotation and thermal characteristics is believed to dominate otherdynamical effects in driving the delivery of small NEOs from themain asteroid belt Studies of the taxonomic distribution of a largesample of NEOs of a wide range of sizes will test this hypothesisWe present a preliminary analysis of the reflectance spectraobtained in our survey to date including taxonomic classificationsand potential trends with sizeAcknowledgements Based on observations obtained with theApache Point Observatory 35-meter telescope which is owned andoperated by the Astrophysical Research Consortium We gratefullyacknowledge support from NASA NEOO award NNX14AL17G andthank the University of Chicago Department of Astronomy andAstrophysics for observing time in 2014

Author(s) Mark Hammergren Melissa J Brucker KristieA Nault Geza Gyuk Michael R SolontoiInstitution(s) 1 Adler Planetarium 2 Lynchburg College

21315 ndash A 3 mircon spectral survey of Jupiter trojansThe surface compositions of Jupiter trojans remain mysteriousWhile the red colors have often been taken to be indicative of thepresence of organic materials no distinct spectral features havebeen found in reflectance spectroscopy spanning 04 - 25 micronswhile thermal emission spectroscopy has shown only the signatureof fine-grained silicates Many materials which may reside on thesurfaces of Jupiter trojans have their strongest fundamental bandsin the 3-4 micron region making this spectral region a prime targetfor understanding composition of otherwise featureless objectsWe have obtained 2-4 micron spectra of 16 large Jupiter trojansusing the NIRSPEC instrument at the Keck Observatory We findsignificant variability in the spectral behavior across this rangeWhile some of the Jupiter trojan asteroids remain featurelessothers have a deep absorption at 3 microns The depth of this 3micron absorption feature is strongly correlated with the opticalcolor of the individual asteroid We will discuss possible spectralidentifications of this spectral feature the implications of the color-absorption correlation and conclusions to be drawn on the sourceof the Jupiter trojans

Author(s) Michael E BrownInstitution(s) 1 Caltech

21316 ndash A Near-Infrared Spectral Survey of HungariaRegion Asteroids Compositionally Diverse Neighborsof the Terrestrial PlanetsThe surface compositions of Hungaria region asteroids are poorlyunderstood These neighbors to the terrestrial planets are uniqueas they are found interior to the Main-belt and have resided in theircurrent location since early in solar system history Mars-crossingand near-Earth asteroids make closer approaches to the terrestrialplanets but they are dynamically short-lived (~10 Myr) escapees

from the Main-belt Original planetesimals within the terrestrialplanet region were either accreted or scattered out early in solarsystem history leaving the Hungarias as the closest remainingldquosurvivorsrdquo of the asteroidal material from which the terrestrialplanets accretedWe have undertaken an observational campaign to record thenear-infrared reflectance spectra of 42 (36 background 6 family)Hungaria asteroids with absolute magnitudes H lt16 tocharacterize their surface mineralogy through spectral bandparameter measurements By comparing these telescopic data withspectral and geochemical data obtained in the laboratory fromldquofreerdquo asteroid samples that arrive to Earth as meteorites we canestablish connections between Hungaria asteroids and analogousmeteorite groupsWe find evidence of three main meteorite-groups represented inthe Hungaria region 1) enstatite achondrites (ie aubrites) 2)ordinary chondrites (ie H L and LL) and 3) primitiveachondrites (ie acapulcoites and lodranites) Five of the sixHungaria family members are spectrally consistent with the largestcollisional fragment (434) Hungaria which is widely considered tobe related to fully-melted aubrite meteorites Analyses of spectralband centers and band area ratios for 25 of 36 Hungariabackground objects reveal evidence for two other meteorite groupsPublished laboratory data for ordinary chondrites compared withour asteroid spectra point to the existence of unmelted L and LLchondrites in the region Preliminary results from the laboratoryanalyses of our suite of 12 primitive achondrites indicate theexistence of partially-melted primitive achondrites in the region aswell These asteroid-meteorite connections suggest thatplanetesimals in the Hungaria region have experienced varyingdegrees of petrologic evolution

Author(s) Michael P Lucas Joshua P Emery NoemiPinilla-Alonso Sean S Lindsay Vania LorenziInstitution(s) 1 Department of Earth amp Planetary SciencesUniversity of Tennessee 2 Department of Physics amp AstronomyUniversity of Tennessee 3 Fundacioacuten Galileo Galilei - IstitutoNazionale di Astrofisica

21317 ndash Error Analysis of Stereophotoclinometry inSupport of the OSIRIS-REx MissionStereophotoclinometry has been used on numerous planetarybodies to derive the shape model most recently 67P-Churyumov-Gerasimenko (Jorda et al 2014) the Earth (Palmer et al 2014)and Vesta (Gaskell 2012) SPC is planned to create the ultra-highresolution topography for the upcoming mission OSIRIS-REx thatwill sample the asteroid Bennu arriving in 2018 This shape modelwill be used both for scientific analysis as well as operationalnavigation to include providing the topography that will ensure asafe collection of the surfaceWe present the initial results of error analysis of SPC with specificfocus on how both systematic and non-systematic error propagatethrough SPC into the shape model For this testing we havecreated a notional global truth model at 5cm and a single region at25mm ground sample distance These truth models were used tocreate images using GSFCs software Freespace Then these imageswere used by SPC to form a derived shape model with a groundsample distance of 5cmWe will report on both the absolute and relative error that thederived shape model has compared to the original truth model aswell as other empirical and theoretical measurement of errorswithin SPCJorda L et al (2014) The Shape of Comet 67PChuryumov-Gerasimenko from RosettaOsiris Images AGU Fall MeetingP41C-3943 Gaskell R (2012) SPC Shape and Topography ofVesta from DAWN Imaging Data DSP Meeting 44 20903Palmer L Sykes M V Gaskll RW (2014) Mercator mdashAutonomous Navigation Using Panoramas LPCS 45 1777

Author(s) Eric Palmer Robert W Gaskell John R WeirichInstitution(s) 1 Planetary Science Institute

21318 ndash From microscope to telescope Usinglaboratory spectroscopic measurements to constrain

1 11 1 2

1

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1 11 2 3

1 1 1

56

the thermal evolution of silicate bodies in the solarsystemSpectral measurements of planets and asteroids have long beenused to inventory the composition of their surfaces If laboratorytechniques can be extrapolated to the larger spatial scales of remoteobservations infrared spectroscopic measurements offer thepotential to delve even deeper into the thermal evolution of thesebodies However the scattering of light and mixing from themicroscopic through macroscopic scales greatly complicates theanalysis of components present even when surfaces are viewed atcomparably high spatial resolution (lt10-100 mpixel) For thisproject we have prepared and measured a set of meteorites andterrestrial analog rocks to perform coordinated spectroscopicstudies from microscopic spectral measurements across individualgrains through measurement of bulk mineral and rock samples inultra-high vacuum (UHV) to investigate two questions (1) canmicroscopic mineral textures related to cation ordering andexsolution be reliably distinguished from physical mixtures asoccur in regoliths and (2) can internally bound water in minerals bedistinguished from water that has adsorbed from the environmentIn each case we explore how well the laboratory techniquesaddress these questions and through spectral modeling what thelimitations and challenges are for extrapolating thesemeasurements to remote observations

Author(s) Rachel L Klima Brianna C Young Andy SRivkinInstitution(s) 1 Johns Hopkins University Applied PhysicsLaboratory

21319 ndash New insights into asteroid 3200 Phaethonsmeteor complexIn this work we study the meteor complex originating fromasteroid 3200 Phaethon Using a modeling of variety of meteoroidstreams and following their dynamical evolution we confirm thepresence of two filaments crossing the Earth observed as Geminidand Daytime Sextantid meteor showers We use numericalintegrations of modeled particles performed for several pastperihelion passages of the asteroid considering (i) only the gravityof planets and (2) gravity of planets and the Poynting-Robertsoneffect We present the results of comparing our models (predictedshowers) with observed showers We also point out discrepanciestheir possible solutions andor new hypothesis concerning theexamined meteor complex

Author(s) Marian Jakubik Lubos NeslusanInstitution(s) 1 Astronomical Institute of the Slovak Academyof Sciences

21320 ndash Scale-Dependent Measurements of MeteoriteStrength and Fragmentation Tamdakht (H5) andAllende (CV3)Meteorites are pieces of natural space debris which have survivedejection from their parent bodies and passage through the Earthrsquosatmosphere As such they provide a unique opportunity to studythe fundamental physical and mechanical properties of early SolarSystem materials But to date few direct studies of physicalproperties have been conducted on meteoritic materials in contrastto extensive chemical and isotopic analyses It is important todetermine these properties as they are related to disruption andfragmentation of bolides and asteroids and activities related tosample return and hazardous asteroid mitigation Here we presentresults from an ongoing suite of scale-dependent studies ofmeteorite strength and fragmentation The meteorites studied areTamdakht (H5) an ordinary chondrite that exhibits aheterogeneous structure criss-crossed with shock veins andcentimeter-sized regions of white and light grey and thecarbonaceous chondrite Allende (CV3) which suitable pieces arelight grey with abundant chondrules and CAIs Uniaxialcompression tests are performed on meteorite cubes ranging from05 to 4 centimeters using an Instron 5985 frame with a 250 kNload cell and compression fixtures with 145mm diameter radialplatens All tests are conducted at room temperature and indisplacement control with a displacement rate of 025 mm per

minute to ensure quasi-static conditions A three-dimensionaldigital image correlation (DIC) system that enables noncontactmeasurement of displacement and strain fields is also usedAnalysis of the strength and failure process of the two meteoritetypes is conducted and compared to terrestrial materials

Author(s) Desireeacute Cotto-Figueroa Erik Asphaug LaurenceGarvie Melissa Morris Ashwin Rai Aditi Chattopadhyay Nikhilesh ChawlaInstitution(s) 1 Arizona State University 2 State University ofNew York at Cortland

21321 ndash Compositional study of asteroids in theErigone collisional family using visible spectroscopyat the 104m GTCAsteroid families are formed by the fragments produced by thedisruption of a common parent body (Bendjoya amp Zappalagrave 2002)Primitive asteroids in the solar system are believed to haveundergone less thermal processing than the S-complex asteroidsThus study of primitive asteroid families provides informationabout the solar system formation period The Erigone collisionalfamily together with other three families (Polana Clarissa andSulamitis) are believed to be the origin of the two primitiveNear-Earth asteroids that are the main targets of the NASArsquosOSIRIS-REx ((101955) Bennu) and JAXArsquos Hayabusa 2 ((162173)1999 JU3) missions (Campins et al 2010 Campins et al 2013Lauretta et al 2010 Tsuda et al 2013) These spacecrafts will visitthe asteroids and a sample of their surface material will bereturned to Earth Understanding of the families that areconsidered potential sources will enhance the scientific return ofthe missions The main goal of the work presented here is tocharacterize the Erigone collisional family Asteroid (163) Erigonehas been classified as a primitive object (Bus 1999 Bus amp Binzel2002) and we expect the members of this family to be consistentwith the spectral type of the parent body We have obtained visiblespectra (05-09 μm) for 101 members of the Erigone family usingthe OSIRIS instrument at the 104m Gran Telescopio Canarias Weperformed a taxonomical classification of these asteroids findingthat the number of primitive objects in our sample is in agreementwith the hypothesis of a common parent body In addition we havefound a significant fraction of asteroids in our sample that presentevidences of aqueous alteration Study of aqueous alterations isimportant as it can give information on the heating processes ofthe early Solar System and for the associated astrobiologicalimplications (it has been suggested that the Earthrsquos present watersupply was brought here by asteroids instead of comets inopposition to previous explanations (Morbidelli et al 2000)

Author(s) David Morate Julia de Leoacuten Maacuterio De Praacute Javier Licandro Antonio Cabrera-Lavers Humberto Campins Noemiacute Pinilla-Alonso Viacutector Aliacute-LagoaInstitution(s) 1 GTC Project Office 2 Instituto de Astrofisica deCanarias 3 Lagrange Boulevard de lrsquoObservatoire 4Observatoacuterio Nacional 5 University of Central Florida 6University of Tennessee

214 ndash Asteroid Dynamics21401 ndash On the dynamical dispersal of primordialasteroid familiesMany asteroid families are identified and well characterized all overthe main belt asteroid Interestingly however none of them areolder than ~4 Gyr Many mechanisms have been proposed todisperse such old primordial asteroid families that presumablyhave existed but none have really worked Here we present aplausible mechanism for dispersing primordial asteroid familiesthat is based on the 5-planet instability model known as jumpingJupiter Using two different evolutions for the jumping-Jupitermodel we have numerically integrated orbits of eight primordialfamilies Our results show that the most important effect on theasteroid families eccentricity and inclination dispersal is that of thesecular resonances in some cases associated with the mean motionresonances As for the semimajoraxes spreading we find that the

1 11

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6 3

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principal effect is that of close encounters with the fifth giant planetwhose orbit briefly overlaps with (part of) the main belt Thereforethe existence of a fifth giant planet with the mass comparable withthat of Uranus or Neptunes could contribute in important ways todispersal of the primordial asteroid families To have that effect theinterloper planet should penetrate and considerably interact withthe asteroids during the instability phase

Author(s) Pedro Ivo de Oliveira Brasil Fernando Roig David Nesvornyacute Valerio Carruba Safwan Aljbaae MarielaEspinoza HaumanInstitution(s) 1 Observatoacuterio Nacional 2 SwRI 3 UNESP

21402 ndash Modeling Asteroid Dynamics using AMUSEFirst Test CasesWe are creating a dynamic model of the current asteroidpopulation The goal is to reproduce measured impact rates in thecurrent Solar System from which well derive delivery rates ofwater and organic material by tracing low-albedo C-class asteroids(using the measured albedo distribution from WISE catalog) theparent bodies of carbonaceous chondrite meteorites Ultimatelywe aim at studying the role of exo-asteroids in the delivery ofwater to exoplanetsOur model is set up using the Astrophysical Multipurpose SoftwareEnvironment (AMUSE amusecodeorg) AMUSE provides acommon Python wrapper around numerous astrophysical codesincluding N-body gravity codes such as Mercury and HuaynoWe report first results towards a validation of our model long-termintegrations of the planets alone as well as studies of the depletionof the Kirkwood gaps in the asteroid belt Further modeldevelopments will be discussed

Author(s) Kateryna Frantseva Michael Mueller Floris vander Tak Frank P HelmichInstitution(s) 1 Kapteyn Astronomical Institute (University ofGroningen) 2 Netherlands Institute for Space Research

21403 ndash Stability of the Slivan statesThe past decade has seen an increase in the number of asteroids forwhich observations allowed resolving the rotation pole orientationThis data led to new studies of asteroids and their populations Oneof the early examples was a discovery of Slivan states in the Koronisfamily (Slivan 2002) The group of prograde-rotating asteroids hadspin axes nearly parallel in inertial space and similar rotationperiods (later dubbed the Slivan states) Vokrouhlicky et al (2003)proposed model based on the idea that the spin axis is confined in aresonance between its precession rate by solar torques and aparticular mode of these asteroidsrsquo orbit precession in the inertialspace (in this case the s mode) The theoretical frameworkdescribing such situation is called Cassini dynamicsSince the past decade the importance of the Cassini dynamics indescription of asteroid rotation has significantly increased we aimto present an efficient tool for its descriptionWe combined two symplectic integration tools into a singlesoftware First we use the widespread and well-tested swiftintegrator for orbital dynamics of the asteroid (Levison amp Duncan1994) Second we included the spin propagator formulated byBreiter et al (2005) into the swift architecture This enables tosimultaneously integrate orbital and rotational dynamics in a singlerunWe show tests that reproduce Slivan states in the Koronis zone Wealso analyse stability of the Slivan states in the inner main beltspecifically in the Flora family region We find Massalia family to bea more suitable inner main-belt location of the classical Slivanstates because of a separation between the s and s nodalfrequencies We also demonstrate that the Slivan states mayassociated with other than the s frequency Under well-tunedconditions the Slivan states may also exists for the s planetaryfrequency For the outer main-belt body 184 Dejopeja we find itspole location near a stable s -associated Slivan state Because theforced inclination of the s term is significantly smaller than that ofthe s term the obliquity range of the s Cassini state is very smallTherefore the new s -related Slivan states are perhaps of only anacademic interest

Author(s) Jan Vrastil David VokrouhlickyInstitution(s) 1 Charles University in Prague

21404 ndash The Orbit and Size of (87) Sylvias Romulusfrom the 2015 ApparitionUsing the US Air Forces Starfire Optical Range 35 meter telescopewith adaptive optics and a laser guidestar we obtained 68 images ofasteroid (87) Sylvia and its satellite Romulus over 10 nights inMarch and May of 2015 Adding an additional 3 images from earlierobservations on one night in November 2012 we are able to derivea circular (but not an eccentric) orbit for Romulus leading to adensity for Sylvia of 137plusmn004 gmcm Extending the time base to14 years by combining our data with previous observations fromKeck HST and the VLT reported in the literature we can fit for anew circular orbit and improve the density estimate to 135plusmn003gmcm By fitting a Fourier series to the measured magnitudedifference between Sylvia (V=125) and Romulus which rangedfrom 41 to 51 in the J-band (λ=12microm) and modeling both astriaxial ellipsoids we are able to derive equatorial ellipsoiddiameters for Romulus of 39x29 both plusmn1 km (All errors here areformal fitting errors) As far as we know our 35 m telescope is thesmallest ground-based telescope to ever image any asteroidsmoon

Author(s) Jack D Drummond Odell Reynolds MilesBuckmanInstitution(s) 1 Starfire Optical Range

21405 ndash The evolution of asteroids in the jumping-Jupiter migration modelIn this work we investigate the evolution of a primordial belt ofasteroids represented by a large number of massless test particlesunder the gravitational effect of migrating Jovian planets in theframework of the jumping-Jupiter model We perform severalsimulations considering test particles distributed in the Main Beltas well as in the Hilda and Trojan groups The simulations startwith Jupiter and Saturn locked in the mutual 32 mean motionresonance plus 3 Neptune-mass planets in a compact orbitalconfiguration Mutual planetary interactions during migration ledone of the Neptunes to be ejected in less than 10 Myr of evolutioncausing Jupiter to jump by about 03 au in semi-major axis Thisintroduces a large scale instability in the studied populations ofsmall bodies After the migration phase the simulations areextended over 4 Gyr and we compare the final orbital structure ofthe simulated test particles to the current Main Belt of asteroidswith absolute magnitude H lt 97 The results indicate that in orderto reproduce the present Main Belt the primordial belt should havehad a distribution peaked at sim10 in inclination and at sim01 ineccentricity We discuss the implications of this for the Grand Tackmodel The results also indicate that neither primordial Hildas norTrojans survive the instability confirming the idea that suchpopulations must have been implanted from other sources Inparticular we address the possibility of implantation of Hildas andTrojans from the Main Belt population but find that thiscontribution should be minor

Author(s) Fernando Virgilio Roig David NesvornyacuteInstitution(s) 1 Observatorio Nacional 2 Southwest ResearchInstitute

21406 ndash Predicting close encounters betweenasteroids with the STB softwareWe have developed a method that can quickly and efficientlycalculate close encounters between all known asteroids both in thepast and the future Only several hundred asteroids out of morethan 690000 have their masses currently known The mostaccurate values are from direct measurements by in situ visits (egDawn at Ceres and Vesta (Russell et al 2012 Science 336 6082pp 684) Hayabusa at Itokawa (Abe et al 2006 Science 312 5778pp 1344-1349)) followed by measurements of binary systems andalso from mutual orbit perturbations during close encountersbetween a handful of the largest MBAsWe used software called ldquoSpace Time Boxrdquo (STB) invented by IBMcapable of efficiently determine co-located entities in 3D space and

1 12 3 3

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6

6

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time Orbits from the MPCORBDAT database were placed intoselected STB granularity with 1 day and 005 AU-wide bins Bydetermining and only tracking asteroids co-located within aselected minimal distance the computational requirements weresignificantly reduced Selected instances of co-location were thenprovided as an input for a numerical integrator SWIFT with 8planets as perturbers and were integrated until desired epoch witha 05 and 1 day timestep We then used interpolation for thespecified time window to check if the positions of asteroidsintersect or are within a certain distance parameterUsing the STB optimization we calculated close encountersbetween years 2014 and 2039 These events offer the opportunityto search in the survey archives for potential collisions andcarefully select the events for mass determination based on theirminimal approach distance angle and mass ratio of participatingobjects A follow-up astrometric campaign would ensureimprovement of the mass determination precision Predictedfuture events can also be directly observed in the real time withoptical and IR telescopes in search for collisions or mass lossAs an example we present one close encounter event observed withthe University of Hawaii 22 m telescope on June 9th 2015

Author(s) Eva Lilly (Schunova) Jeff Jonas MudhakarSrivatsa Raghu Ganti Dakshi Agrawal Larry Denneau Martin Kratky Richard J WainscoatInstitution(s) 1 Comenius University Bratislava 2 IBM 3Institute for Astronomy University of Hawaii

21407 ndash Thermally-driven destruction of asteroids atsmall perihelion distancesState-of-the-art models describing the orbits and absolutemagnitudes of near-Earth objects (NEOs) predict that numerousNEOs should have been found on orbits with small periheliondistances but few actual discoveries have been made In additioneven though the NEO population in general is an even mix oflow-albedo and high-albedo asteroids the characterized NEOs nearthe Sun show a strong preference for high albedos We have foundvia a quantitative comparison of actual NEO detections and a newNEO model accounting for observational selection effects that thedeficit is produced by the super-catastrophic disruption of asubstantial fraction of NEOs when they achieve periheliondistances of a few tens of solar radii The destruction distanceincreases for small asteroids and their temperatures duringperihelion passages do not reach levels where evaporation couldexplain their disappearance Although both bright and darkasteroids eventually disrupt our work shows a preference for theelimination of low-albedo NEOs farther from the Sun whichexplains the apparent excess of high-albedo NEOs and suggeststhat low-albedo asteroids break more easily as a result of thermaleffects

Author(s) Mikael Granvik Alessandro Morbidelli RobertJedicke Bryce Bolin William F Bottke Ed Beshore DavidVokrouhlicky Marco Delbo Patrick MichelInstitution(s) 1 Institute for Astronomy University of Hawaii2 Institute of Astronomy Charles University 3 OCA 4Southwest Research Institute 5 University of Arizona 6University of Helsinki

21408 ndash Monitoring NEO discoveries for imminentimpactorsWe are setting up an automated service that will regularly computeasteroid-Earth collision probabilities for objects on the MinorPlanet Centers Near-Earth-Object Confirmation Page (NEOCP)Our goal is to identify objects similar to 2008 TC and 2014 AA andprovide enough warning time to allow for eg detailed follow-upobservations prior to a collision Our system downloads all the newdata on the NEOCP every 30 minutes and for each object with newdata solves the orbital inverse problem which results in a sample oforbits that describes the typically highly-nonlinear orbital-elementprobability-density function (PDF) We then propagate the orbital-element PDF forward in time for 7 days and compute the collisionprobability as the weighted fraction of the sample orbits that impactthe Earth Our tests have shown that the system correctly predicts

the collisions of 2008 TC and 2014 AA based on the very firstastrometry batches available (collision probabilities greater than70) Using the same configuration we find that the collisionprobabilities for objects typically on the NEOCP based on 4 weeksof continuous operations are always less than 1 in 10 million

Author(s) Otto Solin Mikael Granvik Karri MuinonenInstitution(s) 1 University of Helsinki

21409 ndash Overview of the JPL Center for NEO Studies(CNEOS)Concurrent with the reformulation of NASArsquos Near-Earth Object(NEO) program at NASA Headquarters the Jet PropulsionLaboratory has formed the Center for NEO Studies (CNEOS)which will continue the technical work on NEOs that JPL hasperformed in the past and expand on that work The poster willprovide a brief history of NEO activities at JPL including theestablishment of the original NEO Program Office at JPL in 1998 toprovide a central node of critical expertise in the area of trajectorydynamics of Near-Earth Objects (NEOs) With the reformulation ofthe NEO program at NASA HQ that office has become the Centerfor NEO Studies The poster will review some of the Centerrsquos keyactivities such as the computation of high precision orbits forNEOs tabulation of their close approaches and calculation ofimpact probabilities by all known NEOs over the next century viathe Sentry and Scout impact monitoring systems The Center willcontinue to host the website for NASArsquos NEO Program providingdetailed information on the orbits and physical characteristics of allknown NEOs Other technical activities of the Center will also beoutlined including the Horizons on-line ephemeris service thedevelopment of hypothetical impact scenarios and online kinetic-impactor deflection analysis tools and the detection and mappingof keyholes

Author(s) Paul ChodasInstitution(s) 1 Jet Propulsion Laboratory

21410 ndash Gravitational Influence of a Large CapturedBody on the Stability of Jupiterrsquos Trojan AsteroidsThe Trojan asteroids orbit the Sun about the L4 and L5 Lagrangianpoints of Jupiter These objects have a wide range of eccentricitiesand inclinations and are thought to be captured planetesimalsSince the origin of the Trojan asteroids is expected to provide cluesto the dynamical evolution of the planets and small bodies in theSolar System various models have been proposed eg capturedue to gas drag from the solar nebula capture during Jupiterrsquosmass growth or capture during smooth migration of JupiterHowever such models failed to reproduce some importantcharacteristics of the present Trojan asteroids such as the totalmass of the Trojans the distribution of orbital elements or thedistribution of the libration amplitudes On the other hand recentmodels for the formation of the Solar System suggest that the giantplanets likely experienced significant radial migration and orbitalinstability after their formation Studies of capture of Trojanasteroids based on such models of giant planet migration show thaticy planetesimals originally in the outer Solar System can becaptured into Jupiterrsquos Trojan regions and the present total massas well as the observed orbital characteristics of the Trojanasteroids can be explained in such models However in suchstudies of capture of the Trojan asteroids asteroids were treated astest particles thus gravitational interactions between planetesimalsare not taken into account Although effects of gravitationalinteractions between sufficiently small asteroids may reasonably beneglected there may have been significantly large objects in theoriginal swam of Trojan asteroids immediately after their captureIn the present study we assume that a large body was captured intoJupiterrsquos Trojan region and examine its dynamical influence onother Trojan asteroids using orbital integration From the results ofour calculations we will discuss constraints on the mass of bodiesexisted in the Trojan swarm in the past

Author(s) Keiji Ohtsuki Hiroaki OkayamaInstitution(s) 1 Kobe University

3 22 2 2 3

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2 3 3

3

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215 ndash Mercury and the Moon21501 ndash Observations of the minor species Al Fe andCa in Mercuryrsquos exosphereWe report here on the first observational evidence of Al and Fe inthe exosphere of Mercury based on measurements of 4-5-σresolved emission lines of these metals with Keck-1HIRES AlIemission was observed on two separate runs in 2008 and 2013with tangent column densities of 24 and 3 x 10 Al atoms cm ataltitudes of 1300 and 1850 km (11 and 15 R ) respectively FeIemission has been observed once yielding a tangent column of 62x 10 cm at an altitude of 950 km (14 R ) in 2009 We alsopresent observations of 35-σ Ca emission features nearMercuryrsquos equatorial anti-solar limb in 2011 from which astringent tangent column abundance of 40 x 10 cm is derivedfor the Ca ionA simple model for zenith column abundances of the neutralspecies yields 20 x 10 Al cm and 82 x 10 Fe cm Theobservations appear to be consistent with production of thesespecies by impact vaporization with a large fraction of the Al ejectain molecular form and that for Fe in mixed atomic and molecularforms The scale height of the Al gas is consistent with a kinetictemperature of 4800-8200 K while that of Fe is 5000-13000 KThe apparent high temperature and low density of the Al gas wouldsuggest that it may be produced by dissociation of molecules Alarge fraction of both Al and Fe appear to condense in a vapor cloudat low altitudes

Author(s) Rosemary M Killen Thomas A BidaInstitution(s) 1 Lowell Observatory 2 NASA Goddard SpaceFlight Center

21502 ndash Dissociation of Ca-bearing Molecules as aSource of Mercurys Ca ExosphereObservations of Mercurys calcium exosphere by MESSENGERhave revealed three key features (1) The Ca is extremely energeticwith a temperature ~70000 K if the source is thermal (2) thesource region is located in the dawn hemisphere and (3) there is astrong annual variation in the Ca source rate (Burger et al 2014)Killen and Hahn (2015) have shown that the source rate isconsistent with impact vaporization by interplanetary dust and theintersection of Mercury with a cometary dust stream (likelyassociated with Comet Encke Christou et al submitted)Killen et al (2005) suggested that energetic calcium could beproduced by the dissociation of Ca-bearing molecules produced inimpact vaporization plumes We test this hypothesis with a MonteCarlo model that follows the evolution of atomic and molecularcalcium produced in impact plumes Ca-bearing molecules such asCaO CaOH and Ca(OH) are more likely to be are produced invapor plumes than atomic Ca (Berezhnoy and Klumov 2008)these molecules quickly break apart either through vibrationaldissociation or photodissociation The excess energy associatedwith dissociation gives the atomic Ca an extra energy boost abovethe temperature of the impact plumes (~5000 K) We determineimpact vaporization rates and excess energies required by thedissociation process to reproduce the scale height and spatialmorphology of the Ca exosphere as observed by the MESSENGERUltraviolet and Visible Spectrometer (UVVS)ReferencesBerezhnoy AA and Klumov BA Impacts as sources of theexosphere on Mercury Icarus 195 511-522 2008doi101016jicarus200801005Burger MH et al Seasonal variations in Mercurys daysidecalcium exosphere Icarus 238 51-58 2014doi101016jicarus201404049Killen RM et al The calcium exosphere of Mercury Icarus 173300-311 2005 doi101016jicarus200408022Killen RM and Hahn JM Impact vaporization as a possiblesource ofMercurys calcium exosphere Icarus 250 230-237 2015doi101016jicarus201411035

Author(s) Matthew H Burger Rosemary M KillenInstitution(s) 1 GSFC 2 Morgan State University

21503 ndash Comparing Different Exospheric Species atMercury to Constrain Source Loss and TransportProcessesMercuryrsquos exosphere is maintained by processes that eject atoms ormolecules from the surface of the planet The atoms are initially apart of the regolith or are possibly delivered to the planet viameteorites In either case spatial and temporal variations in sourceprocesses dynamical transport processes such as radiationpressure and ion recycling and the surface chemistry associatedwith exospheric atoms impacting the regolith affect the distributionof species in the exosphere Each of these processes acts differentlydepending on the particular atom due in part to the atomic masssurface sticking coefficient and thermal accommodationcoefficient of the atom A comparison between the differences andsimilarities in the spatial distribution and temporal variations ofmore than one atomic species helps to unravel the physicalprocesses driving the exosphere and ultimately helps to understandsurface-exosphere interactions The Mercury Atmospheric andSurface Composition Spectrometer (MASCS) on the MESSENGERspacecraft obtained profiles of Mercuryrsquos exosphere during threeMercury flybys and during the orbital phase of the mission fromMarch 2011 through April 2015 Specifically MASCS a scanning-grating monochromator observed resonantly scattered emissionsat discrete wavelengths from atoms in the exosphere A strategywas employed where several exospheric species were observedsequentially with integration times short enough that theobservations for a particular set of exospheric atoms were almostsimultaneous These measurements are useful for comparing thedistributions of different atoms since the geometry associated withthe observation of each species is approximately the same I willpresent results from an analysis of MASCS data comparing thedifferences and similarities of the spatial distributions andtemporal variations of different exospheric species

Author(s) Eric Todd BradleyInstitution(s) 1 Univ of Central Florida

21505 ndash Characterizing Water and Hydroxyl onAirless Bodies from Vacuum UV and IR MeasurementsWater exists in the surfaces of airless bodies as ice and potentiallyas adsorbed species [1] either as molecular water or dissociatedinto hydroxyl when bulk water (ice) is not stable [2] All physicalstates of water have a strong spectral signatures in the infraredfrom 27 to 3-um because of a fundamental OH-cation or H-O-Hstretch vibration But the IR is not always definitive of physicalstate Although a band at 307 um is associated with water ice analmost identical band exists in some hydrated minerals Brucite analteration product of olivine possesses this band [6] as doesgoethite another alteration mineral of basalts [7] In fact the305-um band on Ceres which was initially attributed to water icehas more recently been attributed to brucite [6] Spectralobservations in the UV can potentially resolve this degeneracy Inthe UV water ice possesses a very strong band near 180 nm [8]but adsorbed molecular water does not induce a band Because ofthis a combination of UV measurements at wavelengths from ~150 nm to ~200 nm and IR measurements near 3 um candiscriminate ice from adsorbed water The UV region however isalso sensitive to silicate composition with iron bearing mineralshaving a strong OMCT absorption feature near 300 nm and againshortward of 200 nm that can potentially be a source of confusionbetween the identification of iron-poor minerals and water ice Inconclusion the IR can sense all three forms of water (ice adsorbedmolecular water and hydroxyl) and the UV being sensitive to icemay potentially be used either alone or with the IR to identify waterice separately from other phases of hydrationReferences [1] Hibbitts et al Icarus 213 64-72 2011 [2]Schorghofer N and GJ Taylor JGR 112 E02010doi1010292007 [3] Poston et al JGR 118 105-115 2013 [4] Dyar et alIcarus 208425-437 2010 [5] Zeller et al JGR 71 4855-48601966[6] Milliken RE and AS Rivkin Nature Geosci DOI101038 2009 [7] Beck P et al 42 LPSC 2047 2011 [8]Hendrix AR and CJ Hansen Icarus 193 323-333 2008

+

7 -2

M

8 -2 M+

6 -2

7 -2 8 -2

2 1

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1

nd

60

Author(s) Charles A HibbittsInstitution(s) 1 JHU-APL

21506 ndash Revised Age Constraints on Absolute AgeLimits for Mercurys Kuiperian and MansurianSystemsOn the basis of morphologically distinct basin and crater depositsMercuryrsquos surface units have been subdivided into fivetime-stratigraphic systems (youngest to oldest) KuiperianMansurian Calorian Tolstojan and pre-Tolstojan Approximateage limits were initially suggested for these systems on the basis ofthe lunar-derived impact-flux history High-resolution andmulti-band image data obtained by the MErcury Surface SpaceENviroment GEochemistry and Ranging (MESSENGER)spacecraft were used to catalogue fresh impact craters interpretedto have formed during the Mansurian and Kuiperian systemsMansurian and Kuiperian craters are characterized asmorphologically fresh with crisp morphologies well-preservedrims few or no superposed craters continuous ejecta with radiallineaments and well-defined secondary craters Kuiperian cratershave bright ray systems while Mansurian craters maintain freshmorphologies but no longer have discernable ray systemsThe density of fresh craters in these datasets along with the recentproduction and chronology function of Marchi et al [2009] areused to estimate new limits for the boundaries of the two mostrecent of Mercuryrsquos systems Given the effects of strength andother parameters (such as density) we estimate a model age for thepopulation of craters that have formed since the onset of theMansurian of ~19 plusmn03 Gyr Likewise we estimate a model age forthe population of craters that have formed since the onset of theKuiperian of ~300 plusmn40 Myr A particularly good fit for theMansurian crater size frequency distribution (SFD) was found forthe NEO-derived crater distribution The same is true for theKuiperian SFD although the fit is not as robust as for theMansurian SFD

Author(s) Maria E Banks Xiao Zhiyong Sarah E Braden Simone S Marchi Nadine G Barlow Clark R Chapman CalebI FassettInstitution(s) 1 Arizona State University 2 Department ofSpace Studies Southwest Research Institute 3 Dept ofAstronomy Mount Holyoke College 4 NASA Lunar ScienceInstitute Southwest Research Institute 5 Northern ArizonaUniversity 6 Planetary Science Institute 7 School of EarthSciences China University of Geosciences (Wuhan)

21507 ndash The Lunar Reconnaissance Orbiter - SixYears of Science and Exploration at the MoonThe LRO mission currently in an extended mission phase isproducing a remotely sensed dataset that is unrivaled in planetaryscience With an ever-increasing baseline of measurements theLRO data has revealed the Moonrsquos surface and environment to bedynamic with new craters and distal ejecta variations in volatiles atand near the surface a variable exosphere and a surface thatresponds to variations in the flux of radiation from the Sun Takentogether the LRO dataset has significant value in forming how weunderstand airless bodies work in the Solar System and howplanets evolve We will discuss recent observations from themission including geologically recent volcanism contemparayimpacts and polar volatilesWe will also discuss the missions support of future exploration ofthe Moon As initially conceived one of the primary objectives forthe Lunar Reconnaissance Orbiter (LRO) was to identify safelanding sites for future human and robotic exploration and LROmission remains capable of targeted high resolution observationsto support the planning of future robotic missions to the MoonThe LRO team seeks to engage with mission planners to discussLROs enabaling capabilities

Author(s) John W Keller Noah E Petro Timothy PMcClanahan Richard R VondrakInstitution(s) 1 NASAGoddard Space Flight Center

21508 ndash Secondary electron emission from lunar soil

by solar wind type ion impact LaboratorymeasurementsIntroduction The lunar surface potential is determined bytime-varying fluxes of electrons and ions from the solar windphotoelectrons ejected by UV photons cosmic rays andmicrometeorite impacts Solar wind ions have a dual role in thecharging process adding positive charge to the lunar regolith uponimpact and ejecting negative secondary electrons (SE) Electronemission occurs when the energy from the impacting ion istransferred to the solid ionizing and damaging the materialelectrons with kinetic energy greater than the ionization potential(band gap + electron affinity) are ejected from the solid[1]Experiment We investigate the energy distribution of secondaryelectrons ejected from Apollo soils of varying maturity and lunaranalogs by 4 keV He Soils are placed into a shallow Al cup andcompressed In-situ low-energy oxygen plasma is used to cleanatmospheric contaminants from the soil before analysis[2] X-rayphotoelectron spectroscopy ascertains that the sample surface isclean Experiments are conducted in a PHI 560 system (lt10Torr) equipped with a double-pass cylindrical-mirror electronenergy analyzer (CMA) and μ-metal shield The spectrometer isused to measure SE distributions as well as for in situ surfacecharacterization A small negative bias (~5V) with respect to thegrounded entrance grid of the CMA may be placed on the sampleholder in order to expose the low energy cutoffTo measure SEenergy distributions primary ions rastered over a ~6 x 6 mm areaare incident on the sample at ~40deg relative to the surface normalwhile SE emitted with an angle of 423degplusmn 35deg in a cone areanalyzedResults The energy distribution of SE ejected from 4 keV He ionirradiation of albite with no bias applied shows positive charging ofthe surface The general shape and distribution peak (~4 eV) areconsistent with spectra for low energy ions on insulatingmaterial[1]Acknowledgements We thank the NASA LASER program forsupportReferences [1]P Riccardi R Baragiola et al (2004) SurfScience 57 L305-L310 [2]CA Dukes amp RA Baragiola (2010)Surface Interface Anal 42 40-44

Author(s) Catherine Dukes Caixia Bu Raul A BaragiolaInstitution(s) 1 Univ Of Virginia

21509 ndash Comparison of Computational Techniquesfor Estimating Solar Wind Ion Sputtering Yields onSilicatesBodies in space containing silicates and oxides continuouslyexperience ion collisions that result in surface sputteringKnowledge of sputter yields allows for the estimation of destructionrates of small grains in protoplanetary clouds and predictions ofexosphere densities around small bodies to be carried outHowever sputter yields for astrophysical type materials are poorlyconstrained and there has been little work to comparecomputational models to experimental results Theoretical modelsusing sputtering yields commonly use the software SRIM tosimulate ion implantation into solids However the program hasbeen shown to give results that are in poor agreement withexperimental data for low energy (lt10 keV) incident ions typical ofthe solar windHere we compare predicted sputtering yields from SRIM and aprogram based on the TRIMSp algorithm called SDTrimSP Bothprograms were designed to simulate atomic collisions inamorphous targets with predefined stoichiometric compositionsand atomic binding energies During the simulation a onedimensional target is exposed to an incident beam of particles witha composition and energy determined by the user The binarycollision approximation is used to handle the collisions and theenergy loss of the incident particle and energy gain of the recoil isthen calculated This process is repeated for resulting collisionsuntil all particle energies fall below a preset value or have left thetarget However SDTrimSP can account for changing surfacecomposition with increasing irradiation fluence and also providesthe option to use several different surface binding energy modelsSimulations of H and He irradiation of simple oxides were run

1

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using both programs at energies in the 01-10 keV range andcompared to published experimental data SDTrimSP was seen todisplay a better agreement with this data than SRIM making it amore reliable method of estimating sputtering yields The modelwas then expanded to simulate more complex meteoritecompositions in order to determine the timescale at whichequilibrium is achieved

Author(s) Adam Hutcherson Micah Schaible RobertJohnsonInstitution(s) 1 University of Virginia

216 ndash Beyond the Moon The LunarCommunity Branches Out21601 ndash NASAs Solar System Exploration ResearchVirtual Institute (SSERVI)NASAs Solar System Exploration Research Virtual Institute(SSERVI) represents a close collaboration between sciencetechnology and exploration and was created to enable a deeperunderstanding of the Moon and other airless bodies SSERVI issupported jointly by NASArsquos Science Mission Directorate andHuman Exploration and Operations Mission Directorate Theinstitute currently focuses on the scientific aspects of explorationas they pertain to the Moon Near Earth Asteroids (NEAs) and themoons of Mars but the institute goals may expand depending onNASAs needs in the future The 9 initial teams selected in late2013 and funded from 2014-2019 have expertise across the broadspectrum of lunar NEA and Martian moon sciences Theirresearch includes various aspects of the surface interiorexosphere near-space environments and dynamics of thesebodiesNASA anticipates a small number of additional teams to be selectedwithin the next two years with a Cooperative Agreement Notice(CAN) likely to be released in 2016 Calls for proposals are issuedevery 2-3 years to allow overlap between generations of instituteteams but the intent for each team is to provide a stable base offunding for a five year period SSERVIs mission includes acting asa bridge between several groups joining together researchers from1) scientific and exploration communities 2) multiple disciplinesacross a wide range of planetary sciences and 3) domestic andinternational communities and partnershipsThe SSERVI central office is located at NASA Ames ResearchCenter in Mountain View CA The administrative staff at thecentral office forms the organizational hub for the domestic andinternational teams and enables the virtual collaborativeenvironment Interactions with geographically dispersed teamsacross the US and global partners occur easily and frequently ina collaborative virtual environment This poster will provide anoverview of the 9 current US teams and international partners aswell as information about outreach efforts and future opportunitiesto participate in SSERVI

Author(s) Yvonne J PendletonInstitution(s) 1 NASA Ames Research Center

21602 ndash Extending the Lunar Mapping and ModelingPortal ndash New Capabilities and New WorldsNASArsquos Lunar Mapping and Modeling Portal (LMMP) provides aweb-based Portal and a suite of interactive visualization andanalysis tools to enable mission planners lunar scientists andengineers to access mapped lunar data products from past andcurrent lunar missions (httplmmpnasagov) During the pastyear the capabilities and data served by LMMP have beensignificantly expanded New interfaces are providing improvedways to access and visualize data Many of the recentenhancements to LMMP have been specifically in response to therequirements of NASAs proposed Resource Prospector lunarrover and as such provide an excellent example of the applicationof LMMP to mission planningAt the request of NASArsquos Science Mission Directorate LMMPrsquostechnology and capabilities are now being extended to additionalplanetary bodies New portals for Vesta and Mars are the first of

these new products to be releasedOn March 31 2015 the LMMP team released Vesta Trek(httpvestatrekjplnasagov) a web-based application applyingLMMP technology to visualize the asteroid Vesta Data gatheredfrom multiple instruments aboard Dawn have been compiled intoVesta Trekrsquos user-friendly set of tools enabling users to study theasteroidrsquos featuresReleased on July 1 2015 Mars Trek replicates the functionality ofVesta Trek for the surface of Mars While the entire surface of Marsis covered higher levels of resolution and greater numbers of dataproducts are provided for special areas of interest Early releasesfocus on past current and future robotic sites of operation Futurereleases will add many new data products and analysis tools asMars Trek has been selected for use in site selection for the Mars2020 rover and in identifying potential human landing sites onMarsOther destinations will follow soon The Solar Sytem ExplorationResearch Virtual Institute which manages the project invites theuser community to provide suggestions and requests as thedevelopment team continues to expand the capabilities of theseportalsThis presentation will provide an overview of all three portalsdemonstrate their uses and capabilities highlight new featuresand preview coming enhancements

Author(s) Brian Day Emily LawInstitution(s) 1 NASA AMES Research Center 2 NASA Jetpropulsion Laboratory

217 ndash Venus21701 ndash Ionospheric Modulation of Venus ExpressLightning Detection RatesVenus Express completed its nearly 9 year campaign at Earthrsquossister planet in late 2014 During this period the onboard fluxgatemagnetometer collected data up to 64 Hz in frequency while nearperiapsis This is the expected frequency range for lightning-generated whistler-mode waves at Venus between the localelectron and ion gyrofrequencies These waves are right-handcircularly polarized and are guided by the local magnetic fieldWhen the Venusian ionopause is low enough in altitude to residein the collisional region the interplanetary magnetic field can getcarried down with the ions and magnetize the lower ionosphere Asthe field travels towards the terminator it gains a radial componentenabling whistlers to reach higher altitudes and be detected by thespacecraftThe mission covered almost an entire solar cycle and frequentlyobserved a magnetized ionosphere during the solar minimumphase when the ionosphere was weak due to reduced incidentEUV Detection was most common at 250 km altitude where thewaves travel more slowly due to reduced ionospheric density Inresponse they increase in amplitude in order to conserve magneticenergy flux Here we examine the changes in the ionosphericproperties associated with the evolution of the solar cycle and therate of detection of these lightning-generated signals

Author(s) Richard A Hart Christopher T Russell TielongZhangInstitution(s) 1 Austrian Academy of Science 2 University ofCalifornia Los Angeles

21702 ndash Chemistry in the Venus clouds Sulfuric acidreactions and freezing behavior of aqueous liquiddropletsVenus has a thick cloud deck at 40-70 km altitude consisting ofliquid droplets and solid particles surrounded by atmosphericgases The liquid droplets are highly concentrated aqueoussolutions of sulfuric acid ranging in concentration from 70-99 wtWeight percent drops off with altitude (Imamura and Hashimoto2001) There will be uptake of atmospheric gases into the dropletsolutions and the ratios of gas-phase to liquid-phase species willdepend on the Henryrsquos Law constant for those solutions Reactionsof sulfuric acid with these gases will form products with differing

1 11

1

1 2

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62

solubilities For example uptake of HCl by H SO H O dropletsyields chlorosulfonic acid ClSO H (Robinson et al 1998) insolution This may eventually decompose to thionyl- or sulfurylchlorides which have UV absorbances HF will also uptakecreating fluorosulfonic acid FSO H which has a greater solubilitythan the chloro- acid As uptake continues there will be manydissolved species in the cloudwaters Baines and Delitsky (2013)showed that uptake will have a maximum at ~62 km and this isvery close to the reported altitude for the mystery UV absorber inthe Venus atmosphere In addition at very strong concentrationsin lower altitude clouds sulfuric acid will form hydrates such asH SO H O and H SO 4H O which will have very differentfreezing behavior than sulfuric acid with much higher freezingtemperatures (Carslaw et al 1997) Using temperature data fromVenus Express from Tellmann et al (2009) and changes in H SOconcentrations as a function of altitude (James et al 1997) wecalculate that freezing out of sulfuric acid hydrates can besignificant down to as low as 56 km altitude As a result balloonsaircraft or other probes in the Venus atmosphere may be limited toflying below certain altitudes Any craft flying at altitudes above~55 km may suffer icing on the wings propellers balloons andinstruments which could cause possible detrimental effects(thermal changes reduced buoyancy effects on control surfacesplugging of sample inlets etc) Therefore de-icing equipmentshould be considered when designing aircraft expected to fly athigh altitudes in the Venus clouds

Author(s) M L Delitsky K H BainesInstitution(s) 1 California Specialty Engineering 2 Universityof Wisconsin

21703 ndash Venus Atmospheric Maneuverable PlatformScience MissionOver the past several years we have explored a possible newapproach to Venus upper atmosphere exploration by applyingrecent Northrop (non-NASA) development programs and havecome up with a new class of exploration vehicle an atmosphericrover We will discuss a possible suite of instruments andmeasurements to study the current climate through detailedcharacterization of cloud level atmosphere and to understand theprocesses that control climate on Earth-like planetsOur Venus atmospheric rover concept the Venus AtmosphericManeuverable Platform (VAMP) is a hypersonic entry vehicle withan ultra-low ballistic coefficient that transitions to a semi-buoyantair vehicle (AV) after entering the Venus atmosphere Prior toentry the AV fully deploys to enable lifting entry and eliminates theneed for an aeroshell The mass savings realized by eliminating theaeroshell allows VAMP to accommodate significantly moreinstruments compared to previous Venus in situ explorationmissions VAMP targets the global Venus atmosphere between50ndash65 km altitudes and would be an ideal stable platform foratmospheric and surface interaction measurements We willpresent a straw man concept of VAMP including its scienceinstrument accommodation capability and platformrsquos physicalcharacteristics (mass power wingspan etc) We will discuss thevarious instrument optionsVAMPrsquos subsonic flight regime starts at ~94 km and after lt1 hourthe AV will reach its cruise altitude of ~65 km During this phase offlight the VAMP sensor suite will acquire a pre-defined set ofupper atmosphere measurements The nominal VAMP lifetime atcruise altitude is several months to a year providing numerouscircumnavigation cycles of Venus at mid-latitude The stability ofthe AV and its extended residence time provide the very longintegration times required for isotopic mass analysis VAMPcommunicates with the orbiter which provides data relay andpossibly additional science measurements complementing the insitu measurements from the AV We will specifically focus uponkey factors impacting the design and performance of VAMPscience

Author(s) Ronald S Polidan Gregory Lee Floyd Ross Daniel Sokol Linden BolisayInstitution(s) 1 L-Garde 2 Northrop Grumman AerospaceSystems

21704 ndash Some questions about the Venus atmospherefrom past measurementsThe many missions undertaken in the past half a century to exploreVenus with fly-by spacecraft orbiters descending probes landersand floating balloons have provided us with a wealth of data Thesedata have been supplemented by many ground based observationsat reflected solar wavelengths short and long wave infrared to radiowaves Inter-comparison of the results from such measurementsprovide a good general idea of the global atmosphere Howeverre-visiting these observations also raises some questions about theatmosphere that have not received much attention lately butdeserve to be explored and considered for future measurementsThese questions are about the precise atmospheric composition inthe deep atmosphere the atmospheric state in the loweratmosphere the static stability of the lower atmosphere the cloudsand hazes the nature of the ultraviolet absorber and wind speedand direction near the surface from equator to the pole Theanswers to these questions are important for a betterunderstanding of Venus its weather and climate Themeasurements required to answer these questions require carefuland sustained observations within the atmosphere and fromsurface based stations Some of these measurements should andcan be made by large missions such as Venera-D (Russia) VenusClimate Mission (Visions and Voyages ndash Planetary Science DecadalSurvey 2013-2022 or the Venus Flagship Design ReferenceMission (NASA) which have been studied in recent years but somehave not been addressed in such studies For example the fact thatthe two primary constituents of the Venus atmosphere ndash CarbonDioxide and Nitrogen are supercritical has not been considered sofar It is only recently that properties of binary supercritical fluidsare being studied theoretically and laboratory validation is neededWith the end of monitoring of Venus by Venus Express orbiter inNovember 2014 after nearly a decade of observations and theimminent insertion of JAXArsquos Akatsuki spacecraft into orbitaround Venus it is a good moment to consider the unanswered orunexplored questions about Venus

Author(s) Sanjay LimayeInstitution(s) 1 University of Wisconsin

21705 ndash Long-term variations of carbon monoxideand trace species in the Venus troposphere fromVenus ExpressVIRTIS between 2006-2009The understanding of spatial and temporal variations intropospheric abundances of trace gases such as carbon monoxide iskey to understanding the deep atmosphere of Venus These gasesare entrained in the global circulation as well as being keyingredients to creating the sulfuric acid clouds Long-termtemporal variations of these species across Venusrsquos disc would beprovide key insights into the large-scale circulation and cloudforming processes in the troposphereThe Venus Express spacecraft orbited Venus from April 2006 toDecember 2014 The VIRTIS instrument is a near-infrared imagingspectrometer that covers 03 to 50 microm Nightside thermalemissions at 232 microm is sensitive to CO at 35 km We present longterm abundances of CO and other trace abundances as observed byVIRTIS from April 2006 through October 2008 when the MIRchannel ceased operations We compare the methods of Tsang etal (2009) and Barstow et al (2012) of deriving CO from bandratios We will also provide long-term variations of cloud particlesizes This work is done in conjunction with a study of long-termvariations of 173 microm thermal emission brightnesses a proxy ofcloud optical depth in the lower atmosphere with the same data(McGouldrick and Tsang 2015) This work is supported by NASArsquosPlanetary Mission Data Analysis Program grant numberNNX14AP94G

Author(s) Constantine Tsang Kevin McGouldrickInstitution(s) 1 Southwest Research Institute 2 University ofColorado

21706 ndash Ground-Based Venusian Thermal Structureand Dynamics Observations in August 2010We measured equatorial winds above the cloud tops of Venus and

2 4 23

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63

in the lower thermosphere over 19-23 Aug 2010 (UT) a componentof a Venus measurement program that extends over ~30+ yearsusing ground-based Infrared Heterodyne Spectroscopy (IRHS)IRHS obtains sub-Doppler resolution on molecular transitions ofatmospheric species We used the Heterodyne Instrument forPlanetary Winds and Composition (HIPWAC NASA GoddardSpace Flight Center) at the NASA Infrared Telescope Facility toacquire high-resolution spectra on pressure-broadened COabsorption featuresprobing the lower mesosphere (70 km altitude)with non-LTE core emission that probes the lower thermosphere(110 km) The two features probe the transition from zonal windflow near the cloud tops to subsolar-to-antisolar flow in thethermosphere Fully resolved carbon dioxide transitions weremeasured near the 9528808 cm (10494 microm) rest frequency atresolving power λΔλ = 25times10 on the equator on positionsdistributed about the central meridian and across the terminator at~15deg intervals in longitude The non-LTE emission is solar-pumped and appears only on the daylight side probing subsolar-to-antisolar wind velocity flowing radially from the subsolar pointthrough the terminator which was near the central meridian inthese observations with maximum tangential velocity but zeroline-of-sight projection at the terminator and zero tangentialvelocity but maximum projection at the limb The maximummeasurable Doppler shift thus appears within the disc betweencentral meridian and limb The velocity of the zonal flow isapproximately uniform with constant tangential velocity andmaximum line-of-sight projection at the limb and can bemeasured by the frequency of the absorption line on both thedaylight and dark side Variations in Doppler shift between theobservable features and the differing angular dependence of thecontributing wind phenomena thus provide independentmechanisms to distinguish dynamical processes at the altitude ofeach observed spectral feature Winds up to gt100 ms weredetermined in previous investigations with uncertainties of order10 ms or less This work was supported by the NASA PlanetaryAstronomy Program

Author(s) Tilak Hewagama Theodor Kostiuk TimothyLivengood Tobias Stangier Kelly Fast John Annen ManuelaSornig Pia KrauseInstitution(s) 1 DLR and Univ of Cologne 2 NASA 3NASAGoddard Space Flight Center 4 NASAGoddard SpaceFlight Center (Retired) 5 Univ of Maryland 6 University ofCologne

21707 ndash The Role of Rheological Weakening in theFormation of Narrow Rifts on VenusThe rift zones on Venus are remarkably similar to those seen onEarth despite Venusrsquo current lack of plate tectonics The DevanaChasma rift on Beta Regio accommodates extension in a narrowzone and is associated with volcanism As a result it has often beencompared to the East African Rift (Burov and Gerya 2014 Fosterand Nimmo 1996) It has been suggested that plate boundariesdevelop on Earth because an interconnected network of localizedshear zones (areas of concentrated weakening) can form throughthe lithosphere (Regenauer-Lieb and Yuen 2001) If Venusianrifts such as Devana Chasma are similar to terrestrial plateboundaries then it is possible that shear zones should form inthose locationsMontesi (2013) showed that water-bearing minerals such asmicas which are probably not present on Venus largely dominateweakening in the Earthrsquos crust On Venus melts are likely to playthe role of the weak phase that allows for localization due to its lowviscosity relative to host rocks Weakening due to grain sizereduction is also possible if a dislocation-accommodated grainboundary sliding mechanism is active on Venus (Montesi 2013)Rift stability for Venus-like conditions has been analyzed using themodel of Buck (1991) This model links the evolution oflithospheric strength with the style of rifting (wide narrow ormetamorphic core complex) The crust and mantle are assumed tobe dry diabase and dry olivine respectively (diabase rheologicalparameters are from Mackwell et al (1998) olivine rheologicalparameters are from Hirth and Kohlstedt (2003)) The crustalthickness and surface heat flux are varied based on estimatedvalues from the literature (Nimmo and McKenzie 1998 Buck

2002) Without the inclusion of a weakening mechanism the largemajority of model runs predict wide rifts developing Adding asimplistic exponential decay to the lithospheric yield strengthallows for more narrow rift formation to occur Including explicitweakening processes which may be associated with grain sizereduction or development of a foliation appears necessary toexplain the presence of narrow rifts on Venus

Author(s) Alexis Martone Laurent MontesiInstitution(s) 1 University of Maryland College Park

21708 ndash Reflection and Emission Spectra of Fe-OxidesUnder Venus-Like ConditionsThe Solar Systemrsquos last solid planet for which we have nomineralogy data is Venus Soviet landers acquired images andelemental abundances at six locations on the surface of Venusγ-ray and XRF spectroscopy performed by the landers showed thatthe plains are made of mafic basalts Very large concentrations of Kat the Venera 8 and 13 landing sites indicated the presence ofalkaline basaltsNear-IR and thermal IR remote sensing of Mars both from orbitand at the surface have revealed the layered mineralogicalcomplexity of that planet Dominated by basalts and a wide-varietyof fluid-altered phases the mineralogy of Mars tells a complexstory of wet and dry epochs in a history of dramatic climate changeAt the surface of Venus optical pathlengths are small and there islittle scattering due to hazes The environment around a lander orrover on Venus can be mapped from 04 to 3 μm just as well as ithas been on Mars Laboratory spectra show that the ferric edge at055 μm that makes Mars red shifts to 1 μm at Venus surfacetemperatures (Pieters et al 1986) This spectral feature is causedby strong charge transfer transitions in the UV betweenoverlapping orbitals of iron and oxygen and crystal-field electronictransition bands of ferric Fe (Pieters and Englert 1993) Pressureand temperature will alter and broaden crystal-field electronictransition bands Johnson and Fegley (2000) showed that ahalogenatedhydrated amphibole (tremolite) is metastable onVenus thus metamorphic remnants of an ancient hydrospherecould still exist In future work the reflectance and emission spectraof this phase will also be studied at high temperaturesWe will present reflection and emission spectra of severalFe-oxides up to 450degC and 100 bars These environmentalconditions are programmable in a small off-the-shelf 1 cc chamberthat sits in the optical path of a Nicolet FTIR spectrometer Ourwork will show that ambient pressure and temperature havesignificant effects on Fe-oxide spectra and that both must beunderstood to use near-IR spectroscopy to diagnose themineralogy near a Venus lander

Author(s) Mark A Bullock Con CC Tsang Dan D Durda Jeffrey S KargelInstitution(s) 1 Southwest Research Inst 2 University ofArizona

21709 ndash An Induced Venusian Magnetosphere Modelfor Investigating Venusrsquos InteriorThe deep layers of Venus are usually considered to be similar tothose of the Earth but the parameters of these layers including thesize of the Venusian core remain unknown If Venus has a metalliccore the magnetic field that enters the planet cannot diffuse intothe core within the time scales when the external magnetic field canremain steady The bending of magnetic field lines by the corecould be measured at low altitudes providing information to inferthe core size This method of magnetic sounding has successfullyestimated the size of the lunar core helped by the fact that theEarthrsquos magnetotail can provide a uniform background magneticfield for the Moon At Venus the magnetic field is much morecomplicated as the solar wind interaction with the planet developsan induced magnetosphere Estimating the magnetic induction bythe core in this non-uniform non-axisymmetric magnetic fieldenvironment also requires numerical computationThis study develops an induced Venusian magnetosphere modelthat is suitable for understanding Venusrsquos interior Different fromthe global plasma models this model includes the planetary

2

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1 1

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64

interior in the model domain A tradeoff is the use of magnetostaticequations which enables faster computation in return Thisapproach is similar to that adopted by popular empirical models forthe terrestrial magnetosphere Improved from our previous 2-Dmodel the new 3-D model consists of a conducting core the Venuscounterpart of the Chapman-Ferraro current and the tail currentsheet In a separate scenario a global dipole moment is alsoconsidered The finite element method is used to compute themagnetic field vectors within the induced Venusian magnetopauseWe will present model results as well as their comparisons with themagnetic field measurements by PVO and by the more recent VEXmission

Author(s) Peter J Chi Christopher T Russell Michaela NVillarreal Janet G Luhmann T L ZhangInstitution(s) 1 Department of Earth Planetary and SpaceSciences UCLA 2 Space Research Institute Austrian Academy ofSciences 3 Space Sciences Laboratory University of CaliforniaBerkeley

218 ndash Planetary Rings21801 ndash Investigations of Saturnrsquos Main Rings overBroad Range of WavelengthsAn abundance of information about the characteristics of Saturnrsquosring particles and their regolith can be obtained by comparing thechanges in their brightness color and temperature with changingviewing geometry over a wide range of wavelengths from ultravioletthrough the thermal infrared Data from Cassinirsquos CompositeInfrared Spectrometer (CIRS) Visual and Infrared MappingSpectrometer (VIMS) Imaging Science Subsystem (ISS) andUltraviolet Imaging Spectrograph (UVIS) are jointly studied usingdata from the lit and unlit main rings at multiple geometries andsolar elevations over 11 years of the Cassini mission Using multi-wavelength data sets allows us to test different thermal models bycombining the effects of particle albedo regolith grain size andsurface roughness with thermal emissivity and inertia particle spinrate and spin axis orientationCIRS temperatures ISS colors and UVIS brightness appear to varynoticeably with phase angle but are not a strong function ofspacecraft elevation angle Color temperature and brightnessdependence on solar elevation angle are also observed VIMSobservations show that the infrared ice absorption band depthschange with the solar phase angle in particular between 0-20deg andat high phase This trend indicates that single scatteringapproximation is correct only at low phases (lt20deg) while at highphase multiple scattering must be taken into accountThese results imply that the individual properties of the ringparticles may play a larger role than the collective properties of therings in particular at visible wavelengths The temperature andcolor variation with phase angle may be a result of scattering withinthe regolith as well as scattering between individual particles orclumps in a many-particle-thick layer Initial results from our jointstudies will be presentedThis research was carried out in part at the Jet PropulsionLaboratory California Institute of Technology under contract withNASA Copyright 2015 California Institute of TechnologyGovernment sponsorship is acknowledged

Author(s) Linda J Spilker Estelle Deau RyujiMorishima Gianrico Filacchione Matt Hedman PhilNicholson Josh Colwell Todd Bradley Mark Showalter StuPilorz Shawn Brooks Mauro Ciarniello Institution(s) 1 Cornell University 2 Idaho University 3INAF-IAPS 4 JPL 5 SETI Institute 6 UCLA 7 University ofCentral Florida

21802 ndash Multi-frequency VLA Observations ofSaturnrsquos RingsWe will present the calibration and analysis of recent VLAobservations on Saturn and its rings at Q K Ku and X band (07 ndash36 cm) These observations were collected in January 2015 using8-hr tracks in the CnB array configurations to map the system at

high spatial resolution (comparable to the resolution of availablemicrowave Cassini datasets) while remaining sensitive to largescale structure These data complement and extend Cassiniobservations obtained with its 22-cm radiometer The significantreduction in the emissivity of water-ice at 36 cm relative to that at07 cm results in a strong differential response to the fractionalabundance of non-icy material in the rings which is observablewith VLA The VLA data will confirm and extend our previousnon-icy material distributions derived from Cassini data Increasednon-icy material contamination and changes in the particle sizedistribution affect the brightness temperatures noticeablydifferently at shorter wavelengths (07 - 2 cm) Therefore themulti-wavelength nature of the VLA dataset will enable us todisentangle brightness temperature variations from changes in theparticle size distribution and non-icy material abundance We willpresent an update on the analysis of both the VLA dataset as well asthe ongoing analysis of the Cassini observations

Author(s) Zhimeng Zhang Alexander Hayes Imke dePater Phillip Nicholson Michael Janssen Jeffrey Cuzzi David Dunn Bryan ButlerInstitution(s) 1 Ames Research Center 2 Cornell University 3Jet Propulsion Laboratory 4 National Radio AstronomyObservatory 5 Sierra College 6 University of California atBerkeley

21803 ndash Heating Saturns Clumpy RingsWe model Cassini CIRS data using a Monte Carlo radiative transfer-- thermal balance technique first developed for protostellar diskswith the goals of1 Exploring whether the A- and B-ring temperatures variationwith viewing angle is consistent with the wake structures suggestedby the observed azimuthal asymmetry in optical depth by analyticarguments and by numerical N-body modeling2 Better constraining the shape size spacing and optical depths ofsubstructure in the A-ring using the unexpectedly hightemperatures observed at equinox If the wake features have highenough contrast Saturn-shine may penetrate the gaps between thewakes and heat thering particles both top and bottom3 Determining how much of the heating of the A- and B-ringsunlit sides is due to radiative transport and how much is due toparticle motions especially vertical motions This will help inconstraining the rings surface densities and masses

Author(s) Neal J Turner Ryuji Morishima Linda JSpilkerInstitution(s) 1 JPLCaltech 2 UCLA IGPP

21804 ndash Detections of Propellers in Saturns Ringsusing Machine Learning Preliminary ResultsWe report on the initial analysis of the output of a tool designed toidentify persistent non-axisymmetric features in the rings ofSaturn This project introduces a new paradigm for scientificsoftware development The preliminary results include what appearto be new detections of propellers in the rings of SaturnThe Planetary Data System (PDS) working with the NASATournament Lab (NTL) Crowd Innovation Lab at HarvardUniversity and the Topcoder community at Appirio Inc underthe umbrella ldquoCassini Rings Challengerdquo sponsored a set ofcompetitions employing crowd sourcing and machine learning todevelop a tool which could be made available to the community atlarge The Challenge was tackled by running a series of separatecontests to solve individual tasks prior to the major machinelearning challenge Each contest was comprised of a set ofrequirements a timeline one or more prizes and other incentivesand was posted by Appirio to the Topcoder Community In the caseof the machine learning challenge (a ldquoMarathon Challengerdquo on theTopcoder platform) members competed against each other bysubmitting solutions that were scored in real time and posted to apublic leader-board by a scoring algorithm developed by Appirio forthis contestThe current version of the algorithm was run against ~30000 ofthe highest resolution Cassini ISS images That set included 668

1 11 3 2

4 56 3 2

1 7 7 55 4 3

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5 4

1 21

65

images with a total of 786 features previously identified aspropellers in the main rings The tool identified 81 of thosepreviously identified propellers In a preliminary closeexamination of 130 detections identified by the tool we determinedthat of the 130 detections 11 were previously identified propellerdetections 5 appear to be new detections of known propellers and4 appear to be detections of propellers which have not been seenpreviously A total of 20 valid detections from 130 candidatesimplies a relatively high false positive rate which we hope to reduceby further algorithm development The machine learning aspect ofthe algorithm means that as our set of verified detections increasesso does the pool of ldquoground-truthrdquo data used to train the algorithmfor future use

Author(s) Mitchell K Gordon Mark R Showalter Jennifer Odess Ambi Del Villar Andy LaMora Jin Paik Karim Lakhani Rinat Sergeev Kristen Erickson Carol Galica

Edwin Grayzeck Thomas Morgan William Knopf Institution(s) 1 Appirio Inc 2 Carl Sagan Center SETIInstitute 3 Crowd Innovation LabNASA Tournament Lab atHarvard University 4 Goddard Space Flight Center 5 NASAHeadquarters

21805 ndash Characteristics of Small Scale WaveStructure Near Strong Janus Inner LindbladResonancesRegions of compression and rarefaction within Saturnrsquos ringsinclude Inner Lindblad Resonances (ILR) at spiral density wavesand spiral bending waves at vertical resonances along withsmaller-scale self-gravity and overstability waves However fewinvestigations have searched for structure at scales under 100metersWe investigate Cassini UVIS HSP stellar occultation profilescollected between May 19 2005 and June 2 2013 (Cassinirevolutions 8 - 191) within and near strong A ring and B ring spiraldensity waves We report an unexpected number of statistically-significant gaps in ring optical depth within the density wavesgenerated at strong resonances While the frequency of gaps differsacross resonance locations size distribution power laws at similarregions have similar indices We compare the frequency of gapsbetween the peaks troughs and intermediate regions of the ILRspiral density waves

Author(s) Zarah Brown Morgan Rehnberg LarryEsposito Nicole Albers Miodrag SremčevićInstitution(s) 1 University of Colorado BoulderLASP

21806 ndash Direct numerical modeling of Saturns denserings at high optical depthSaturns B ring exhibits complex optical depth structure ofuncertain origin We are investigating the extent to which viscousoverstability andor gravitational wakes can give rise to thisstructure via discrete particle numerical simulations We use theparallelized N-body tree code pkdgrav with a soft-sphere collisionmodel for detailed treatment of particle collisional physicsincluding multi-point persistent contact with static sliding rollingand twisting friction forces This enables us to perform localsimulations with millions of particles realistic sizes andconfigurable material properties in high-optical-depth ring patcheswith near-linear scaling across multiple processors Recent codeimprovements to the collision search algorithm provide a furtherroughly factor of 2 speedup We present results from the first yearof this study in which a library of simulations with different opticaldepths was constructed Parameters explored include normal(dynamical) optical depths between 05 (approximately 100000particles) and 40 (approximately 83 million particles) in ringpatches of dimension 6 by 6 critical Toomre wavelengths usingmaterial parameters ranging from highly elastic smooth spheres torough gravel-like particles We also vary the particle internaldensities to enhance (low density)suppress (high density) viscousoverstability in order to compare against gravitational instability inthese different regimes These libraries will be used to carry outsimulated observations for comparison with Cassini CIRStemperature measurements and UVIS occulation data of Saturns

dense rings

Author(s) Derek C Richardson Ronald-Louis Ballouz Ryuji MorishimaInstitution(s) 1 Univ of California 2 Univ of Maryland

21807 ndash A survey of the Saturnian ring edges Resultsfrom double star occultationsThe Cassini Ultraviolet Imaging Spectrograph (UVIS) High SpeedPhotometer (HSP) has recorded more than 150 stellar occultationsof Saturns rings About one third are observations involvingdouble stars where each star contributes its own independentlight curve For each light curve its footprint as projected into thering plane and depending on observation geometry samples adifferent region in the ring Here we focus on ring edges Eachoccultation then yields two independent edge measurements at twodifferent times and longitudes We infer relative changes in opticaldepth and radial position over an azimuthal distance as short as 20meters These relative measurements require neither photometricnor geometric calibration and inform on the small-scale variabilityof structurefeatures with relative resolutions an order ofmagnitude higher than typically achievedThe Encke and Keeler gap edges as well as the outer B and A ringedges show radial excursions on the order of tens of meters Theseradial variations are in comparison to the common multi-modeanalysis of edge kinematics high-frequency components withcorresponding m numbers of mgt5000000 We note that spatialdimensions inferred here are 10-100 times smaller than those offeatures Region A and B at the B ring edge or Peggy-type objectsat the A ring edge and are comparable to individual self-gravitywakes or clumpsparticles The Titan and Huygens ringlets innerand outer edges on the other hand are in comparison highlyregular and smooth with radial variations of only a few metersNevertheless they show changes in normal optical depth on theorder of 04 well above the expected margin due to intrinsic stellarvariability We also identified three features in the C ring that showlittle radial variability and can thus be considered smoothInterestingly this irregularity or raggedness of the edges -manifestation of intrinsic small-scale structure of the ring - isstronger with increasing radial distance from Saturn This isconsistent with the current understanding that larger structuresform in regions of weaker tidal forces or perturbed regions such asthe A and B ring edgesThis work is supported by the Cassini project

Author(s) Nicole AlbersInstitution(s) 1 LASPUniversity of Colorado

21808 ndash Modeling Cassini Occultations for HighResolution Simulations of Saturnrsquos RingsWe present the preliminary results of attempts to accurately modelCassini occultations numerically with high-resolution patchsimulations of Saturnrsquos rings The simulations use particledistributions that match measurements of surface densities fromdensity waves and particle sizes distributions that extend down toradii of a decimeter or smaller Synthetic occultationmeasurements are produced using ray tracing techniques withgeometries that match those of various Cassini observations forcomparison

Author(s) Mark C Lewis Josh E ColwellInstitution(s) 1 Trinity Univ 2 University of Central Florida

21809 ndash Simulating ldquoStrawrdquo in the Keeler Gap RegionPrevious simulations by Lewis and Stewart (2005) indicated thatgravity wakes at the edge of the Encke Gap region could grow tokilometers in length through the systematic motion of the ringmaterial produced by the interaction with Pan Recent simulationsof the Keeler gap region indicate that this same process can occurthere as well if there is sufficient surface density to sustain theclustering of particles These simulations use a single large fixedcell and include the eccentricity and inclination of Daphnis Thesefactors lead to time variability that is not seen at the Encke gap Weshow where and how these form at the Keeler Gap and how they

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might appear in occultation and imaging observations

Author(s) Alexander K Hansen Mark C LewisInstitution(s) 1 Trinity University

21810 ndash Physics of Tidal Disruption of Big Objects atthe Close Encounter to SaturnThe origin of Saturns main rings is still debated According to theNice model of Late Heavy Bombardment planets couldexperience significant amount of close encounters with bodiesscattered from primordial Kuiper belt that surrounded the giantplanets Such primordial belt could have been significantly massiveand may have contained a larger number of big objects thancurrently observed in the Kuiper Belt In this work we revisit thephysical processes of tidal disruption of such big object passinginside the Saturns Roche limit and discuss the possibility of themass implantation around Saturn as a result of the tidal disruption[Charnoz et al 2009 Icarus 199 413-428] utilized an analyticalformula that is derived from simply assuming uniform distributionof energy within a body [Dones 1991 Icarus 92 194-203] to obtainmasses that are captured onto bound orbits around planet afterclose encounter However the physical processes of tidaldisruption remained unclear and thus we might need to re-assessthe captured mass In this work we perform SPH simulations ofclose encounters of homogeneous and differentiated bodiesaround Saturn in order to investigate how such objects could betidally destructed and how much mass could be captured aroundSaturn as a result of the destruction We find that our numericalresults are not always consistent with Dones (1991) formula thatin general significantly overestimates or underestimates thecaptured mass as the pericenter distance of the passing objectbecomes larger depending on the mass of objects Effects ofrotation and self-gravity within the body will be also investigatedWe show that there is a wide range of outcomes for tidal disruptionand that the implantation of rings is possible

Author(s) Ryuki Hyodo Seacutebastien Charnoz Keiji Ohtsuki Hidenori GendaInstitution(s) 1 Earth-Life Science Institute Tokyo Institute ofTechnology 2 Institut de Physique du Globe de Paris 3 KobeUniversity

21811 ndash Orbit Averaging in Perturbed Planetary RingsThe orbital period is typically much shorter than the time scale fordynamical evolution of large-scale structures in planetary ringsThis large separation in time scales motivates the derivation ofreduced models by averaging the equations of motion over the localorbit period (Borderies et al 1985 Shu et al 1985) A moresystematic procedure for carrying out the orbit averaging is to useLie transform perturbation theory to remove the dependence onthe fast angle variable from the problem order-by-order in epsilonwhere the small parameter epsilon is proportional to the fractionalradial distance from exact resonance This powerful technique hasbeen developed and refined over the past thirty years in the contextof gyrokinetic theory in plasma physics (Brizard and Hahm RevMod Phys 79 2007) When the Lie transform method is appliedto resonantly forced rings near a mean motion resonance with asatellite the resulting orbit-averaged equations contain thenonlinear terms found previously but also contain additionalnonlinear self-gravity terms of the same order that were missed byBorderies et al and by Shu et al The additional terms result fromthe fact that the self-consistent gravitational potential of theperturbed rings modifies the orbit-averaging transformation atnonlinear order These additional terms are the gravitationalanalog of electrostatic ponderomotive forces caused by largeamplitude waves in plasma physics The revised orbit-averagedequations are shown to modify the behavior of nonlinear densitywaves in planetary rings compared to the previously publishedtheory This reserach was supported by NASAs Outer PlanetsReserach program

Author(s) Glen R StewartInstitution(s) 1 Univ of Colorado

21812 ndash A new look back at the structure of Uranusnarrow ringsWith the Cassini mission to Saturn providing new insights into howrings work a new examination of the available Uranus ring datawill provide further insights into the ringsrsquo structure and dynamicsas well as the planetary interior We investigate the fine-scalequasiperiodic optical depth variations within the Uranian ringsobserved in the Voyager 2 radio and stellar occultations Previousinvestigations of these patterns within the ε δ and γ ringssuggested that some of these may be density waves at locations ofeccentric Lindblad resonances with the satellites Cordelia andOphelia (Porco and Goldreich 1987 AJ) as well as possibleunidentified satellites (Horn et al 1988 Icarus Gresh et al 1989Icarus and Yanamandra-Fisher 1992 ASR) We revisit thesestructures as well as others in the α β 4 5 and 6 rings usingmodern analytical techniques in order to better constrain theirorigins The α and β rings exhibit highly periodic patterns whichhave very different wavelengths in the different occultation cuts(even after accounting for the ringletsrsquo width variations) Weexplore the possibility that these structures could be moonletwakes similar to those found in Saturnrsquos rings near the smallmoons Pan and Daphnis

Author(s) Robert O Chancia Matthew M Hedman RichardG FrenchInstitution(s) 1 University of Idaho 2 Wellesley College

21813 ndash Evolution of regolith depth and fractionalpollution of Saturnrsquos ringsWe model the evolution of the fractional pollution of Saturnrsquosrings by calculating the ratio of exogenous meteoritic material toendogenous icy material native to the ring system Comparison toring spectra can constrain the age of the planetrsquos ring system Weupdate our Markov-chain based model (Elliott and Esposito 2011)to numerically calculate the regolith depth and fractional pollutionof a simulated system of ring particles for a given input meteoriticmass flux distribution into the system over long time scales Weuse new mass flux values recently reported by Kempf et al (EPSC2015) derived from the Cassini Cosmic Dust Analyzer (CDA) tocalculate new fractional pollution values and calculate thebidirectional reflectance spectra using reflectance data of comet67PChuryumovndashGerasimenko obtained by the Alice UVspectrometer onboard the Rosetta spacecraft as the pollutant aswell as several other pollutant species for comparison to CassiniUVIS spectra

Author(s) Joshua Peter Elliott Larry W EspositoInstitution(s) 1 Laboratory for Atmospheric and Space PhysicsUniversity of Colorado 2 National Ecological ObservatoryNetwork

219 ndash EPO - Scientists Showcase Programsand Best Practices21901 ndash Discoveries in the Solar System Spreadingthe Good WordSolar system exploration in recent years has completely capturedthe interest of the public worldwide and we as scientists can play aunique role in disseminating this information The public wants tohear from us about the latest results from the Pluto flyby to see thenewest Titan image to hear stories of the plucky Philae cometlander and to hear our thoughts on the Earth-like exoplanet evenif we are not directly involved in these missions or discoveriesThey trust us because they know our background makes us viablejudges of the value of these endeavors The public relies on us todistill the material which is typically science-jargon-rich intosomething inspiring and digestible by them in the time they haveavailable The best way to start reaching out is to find and distributewhat most excites us because it is clearly obvious when wersquore trulyexcited about something as opposed to just regurgitating the latestand greatest If you like the latest picture from MSL because itlooks like your back yard show a picture of the two next to each

1 1

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2 1

67

other We should be familiar with and even solicit the differentoutreach platforms such as such as social media of various kindspublic talks in all shapes and forms news venues including radioand TV and popular articles Finally we need to know ouraudience prepare and practice I have never given the exact sameoutreach talk twice because the audience is always slightlydifferent The last two public talks I gave were carefully wordedpracticed and even partly memorized which gave me an edge ofpreparedness that allowed me to be more dynamic Being involvedin outreach in the best way for you will make you happier andbetter focused in your research will ensure the public supportsNASA and will make a positive impact in the lives of many people

Author(s) Jani RadebaughInstitution(s) 1 Brigham Young University

21902 ndash Exoplanet Science in the National ScienceOlympiadThe National Science Olympiad is one of the United States largestscience competitions reaching over 6000 schools in 48 states TheOlympiad includes a wide variety of events stretching a full rangeof potential future STEM careers from biological sciences toengineering to earth and space sciences The Astronomy event hasbeen a mainstay at the high school level for well over a decade andnominally focuses on aspects of stellar evolution For the2014-2015 competition season the event focus was aligned toinclude exoplanet discovery and characterization along with starformation Teams studied both the qualitative features ofexoplanets and exoplanetary systems and the quantitative aspectsbehind their discovery and characterization including basiccalculations with the transit and radial velocity methods Studentswere also expected to have a qualitative understanding of stellarevolution and understand the differences between classes of youngstars including T Tauri and FU Orionis variables and Herbig AeBestars Based on the successes of this event topic we are continuingthis event into the 2015-2016 academic year The key modificationis the selection of new exoplanetary systems for students toresearch We welcome feedback from the community on how toimprove the event and the related educational resources that arecreated for Science Olympiad students and coaches We alsoencourage any interested community members to contact yourregional or state Science Olympiad tournament directors andvolunteer to organize competitions and supervise events locally

Author(s) Thaddeus D Komacek Donna YoungInstitution(s) 1 NASA Astrophysics Divison 2 University ofArizona

21903 ndash PACA_Rosetta67P Global AmateurObserving Support for ESARosetta MissionThe PACA (Professional - Amateur Collaborative Astronomy)Project is an ecosystem of several social media platforms(Facebook Pinterest Twitter Flickr Vimeo) that takes advantageof the global and immediate connectivity amongst amateurastronomers worldwide that can be galvanized to participate in agiven observing campaign The PACA Project has participated inorganized campaigns such as Comet Observing Campaign(CIOC_ISON) in 2013 and Comet Siding Spring(CIOC_SidingSpring)in 2014 Currently the PACA Project issupporting ESARosetta mission with ground-based observationsof the comet 67PChuryumov-Gerasimenko (CG) through itsperihelion in August 2015 and beyond providing baselineobservations of magnitude and evolution from locations aroundthe globe Comet 67PCG will reach its brightest post-perihelionand pass closest to Earth in November 2015 We will present thevarious benefits of our professional - amateur collaborationdeveloping and building a core astronomer community defining anobserving campaign from basic information of the comet from itsprevious apparitions coordinating with professionals and themission to acquire observations albeit low-resolution but on along timeline while addressing the creation of several scienceproducts such as the variation of its magnitude over time and thechanging morphology We will present some of our results to dateand compare with observations from professionals and previous

apparations of the comet We shall also highlight the challengesfaced in building a successful collaborative partnership between theprofessional and amateur observers and their resolution With thepopularity of mobile platforms and instant connections with peersglobally the multi-faceted social universe has become a vital part ofengagement of multiple communities for collaborative scientificpartnerships and outreach We shall also highlight other cometaryobserving campaigns that The PACA Project has initiated to evolvethis model of collaborative partnerships

Author(s) Padma A Yanamandra-Fisher ClaudiaAlexander Efrain Morales Christiana Feliciano-RiveraInstitution(s) 1 CITJet Propulsion Laboratory 2 JaicoaObservatory 3 Sloohcom 4 Space Science Institute

21904 ndash STEM education for teachers in the RioGrande ValleyWe have worked with elementary and middle school teachers in theRio Grande Valley for the last 10 years bringing Earth and SpaceScience themed workshops to underserved areas of Texas TheTexas curriculum was also changed to include Astronomy andSpace Science requirement in the tests students need to take toprove their academic preparedness The teachers worked through avariety of inquiry-based hands-on activities after a shortpresentation on the background science In order to evaluate oureffectiveness we have asked the teachers to take pre- andpost-workshop tests and we asked them to fill out a self-reflectivesurvey We will report on our experiences what works best with theteachers and in what areas we still have a long way to goThis work was supported by various NASA education grants andCooperative agreements as well as grants provided by the TexasSpace Grant Consortium

Author(s) Judit Gyorgyey Ries Margaret R BaguioInstitution(s) 1 Univ of Texas Austin

21905 ndash Were mass communicating podcasting asoutreachThe New York Times (July 18th 2015) called podcasting thatrarest thing in the technology industry a subset of media showingsustained growth That same article quotes an Edison Researchreport that found that roughly 15 Americans have listened to apodcast in the last month The most popular podcasts receive amillion downloads per episode and over all podcasts the mediannumber of downloads per episode is ~150 (Libsyn statistics) Thepopularity and easy accessibility of podcasts make them an idealvehicle for outreachThere are several excellent podcasts covering planetary scienceincluding Planetary Radio produced by the Planetary SocietyStarTalk Radio several official NASA podcasts and individualefforts such as Al Grauers Travelers in the Night and Jane JonesWhats upSpacepod is a weekly podcast on space exploration that launched inAugust 2015 Episodes feature an expert guest discussing aninteresting aspect of their job for a general audience Episodes havean intimate conversational feel letting the audience hang outwith space scientists and engineers Spacepod has shown stronggrowth since launch and was featured in iTunes New andNoteworthy section Episodes can be found atwwwlistentospacepodcom and the show tweetslisten2spacepod

Author(s) Carolyn R NugentInstitution(s) 1 CaltechIPAC

21906 ndash The Crossroads of Science and FaithWe have recently completed a 4-year project to produce a textbookfor students that uniquely addresses the needs of the Christianhomeschool community It is also relevant for students of otherfaith and non-faith backgrounds Two elements are at workparents want their kids to become mature adults adhering to thefaith of their upbringing and students are challenged when theydont understand how to rationally discuss their beliefs in relationto many current scientific discoveries To add to the polarization a

1

2 1

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1 1

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68

few scientists have spread an atheistic naturalistic worldviewtogether with their teaching of science as if it was part of scienceitself As a result many parents avoid materials they considercontroversial and students later come to believe they must choosebetween science and their faith The key to bridging this gap areprofessional astronomers who hold to a Christian worldview andwho can speak both languages understanding the complexities ofboth communities The role of science educators is to teachscience not to impose worldviews Science is well received byChristians when it is presented not as a threat to faith but rather asa complementary way to understand God leading to a moreintegrated view of reality Our textbook boasts four hallmarksproviding students with 1) An understanding of the relationshipbetween faith and science with the goal of helping students toidentify and integrate their own worldview 2) Scientificallyreviewed and accurate astronomical information 3) Examples ofscientists who have wrestled with sciencefaith issues and come toa coherent relationship between the two And 4) exercises for thestudents to interact with the material in both faith and scientificareas We hope this will be a resource to help parents who holdtightly to particular ideologies to be less closed to current scientificdiscovery and more excited about how new discoveries can bolsterand enable their faith We will present an overview of ourmaterials the positive experience we have had so far in testing ourmaterials and our goals for future training within the homeschooland church communities For more information about thetextbook see httpwwwglimpseofhissplendorcom

Author(s) Susan D Benecchi Gladys Kober PaulaGossardInstitution(s) 1 Carin University 2 GSFCNASA 3 PlanetaryScience Institute

21907 ndash NASA SMD and DPS Resources for HigherEducation FacultyThe NASA Education and Public Outreach Forums have developedand provided resources for higher education for the past six yearsthrough a cooperative agreement with NASArsquos Science MissionDirectorate Collaborations with science organizations includingAASrsquos Division of Planetary Sciences have resulted in more toolsprofessional training opportunities and dissemination of resourcesfor teaching in the undergraduate classroom Resources have beendeveloped through needs assessments of the community and withinput from scientists and undergraduate instructors All resourcesare freely availableNASA Wavelength (nasawavelengthorg) is a collection of digitalpeer reviewed Earth and space science resources for formal andinformal educators of all levels All resources were developedthrough funding of the NASA Science Mission Directorate and haveundergone a peer-review process through which educators andscientists ensure the content is accurate and useful in aneducational setting Within NASA Wavelength are specific lists ofactivities and resources for higher education faculty Additionallyseveral resources have been developed for introductory collegeclassrooms The DPS Discovery slide sets are 3-slide presentationsthat can be incorporated into college lectures to keep classesapprised of the fast moving field of planetary science(httpdpsaasorgeducationdpsdisc) The ldquoAstro 101 slide setsrdquodeveloped by the Astro Forum are presentations 5-7 slides inlength on a new development or discovery from a NASAAstrophysics mission relevant to topics in introductory astronomycourses of discoveries not yet in textbooks Additional resourcesguides are available for Astro 101 courses and include cosmologyand exoplanets (httpswwwastrosocietyorgeducationresources-for-the-higher-education-audience)Professional development opportunities are available to faculty toincrease content knowledge and pedagogical tools These includeworkshops at scientific meetings and online webinars that arearchived for later viewing For more information visit the SMDEPO community workspace at httpsmdepoorg

Author(s) Sanlyn Buxner Jennifer Grier Bonnie Meinke Nick Schneider Rusty Low Greg Schultz James Manning Andrew Fraknoi Nicholas GrossInstitution(s) 1 Astronomical Society of the Pacific 2 BostonUniversity 3 Foothill College 4 IGES 5 NASA SMD AstroForum 6 Planetary Science Institute 7 Space Telescope ScienceInstitute 8 University of Colorado

21908 ndash Space Scientists in Education and PublicOutreach A Summary of NASA Resources for EffectiveEngagementThe NASA Education and Public Outreach (EPO) Forumsdeveloped and provided resources for scientists through a five-yearcooperative agreement Through this work the Fourms havesupported scientists who are involved in EPO and who wish tobecome involved Forums have conducted interviews facilitatededucation oral and poster sessions provided lsquoHelp Desksrsquo for moreinformation curated activities as well as produced guidespamphlets and tips sheets Our interviews with over 30 planetaryscientists allowed us to identify needs and target gaps in resourcesensuring we could provide scientists with effective support andproducts Interviews were conducted in collaboration with the AASDivision of Planetary Sciences with the goal of betterunderstanding scientistsrsquo requirements barriers attitudes andperception of education and outreach work We collectedinformation about how scientists were engaged in EPO activities(or not) what support they did or did not have what resources theyused in their efforts and what resources they would like to have tosupport and improve their EPO engagement The Forums haveconvened andor supported EPO oral and poster sessions at avariety of annual meetings These sessions allowed scientists tonetwork share lessons learned and become aware of newresources and products These meetings included the DPS AASLPSC AGU ASP IAU and more lsquoHelp Desksrsquo were offered toallow scientists the chance to have extended one-on-oneconversations with EPO providers in order to share theirprograms and learn how to become involved These have beenparticularly popular with early career scientists looking to extendtheir EPO efforts A host of education activities developed by thespace science community have been archived at the NASA siteldquoWavelengthrdquo (nasawavelengthorg) Special lists have beencurated to allow scientists to easily target those activities that fittheir particular needs from engineering to higher education tooutreach at public events Guides information sheets and ldquoHowTorsquosrdquo have been developed to answer specific questions and needsthat scientists have specifically expressed These resources areopenly available at the NASA SMD community site (smdepoorg)

Author(s) Jennifer A Grier Sanlyn Buxner NickSchneider Bonnie Meinke Stephanie ShippInstitution(s) 1 LASPUniversity of Colorado 2 Lunar andPlanetary Institute 3 Planetary Science Institute 4 SpaceTelescope Science Institute

21909 ndash Best Practices in Pulic Outreach EventsIntroductionEach year the National Aeronautics and Space Administration(NASA) sponsors public outreach events designed to increasestudent educator and general public engagement in its missionsand goals NASA SMD Educationrsquos review of large-scale eventsldquoBest Practices in Outreach Eventsrdquo highlighted planning andimplementation best practices which were used by the Dawnmission to strategize and implement its Ceres arrival celebrationevent i C CeresBackgroundThe literature review focused on best identifying practices risingfrom evaluations of large-scale public outreach events Thefollowing criteria guided the study Public science-related events open to adults and children Events that occurred during the last 5 years Evaluations that included information on data collected fromvisitors andor volunteers Evaluations that specified the type of data collectedmethodology and associated results

3 21

6 6 78 4 1 53 2

3 31 4 2

69

Best Practices Planning and ImplementationThe literature review revealed key considerations for planningimplement large-scale events Best practices included can bepertinent for all event organizers and evaluators regardless of eventsize A summary of related best practices is presented below1) Advertise the event2) Use and advertise access to scientists Attendees who reported an interaction with a science professionalwere 15 to 19 more likely to report positive learning impacts(SFA 2012 p 24)3) Recruit scientists using findings such as High percentages of scientists (85 to 96) from most eventswere interested in participating again (SFA 2012)4) Ensure that the event is group and particularly child friendly5) Target specific event outcomesBest Practices Informing Real-world Planning Implementationand EvaluationDawn missionrsquos collaborative design of a series of events i C Ceresincluding in-person interactive events geared to families and livepresentations will be shared with focus on the family event andthe evidence that scientist participation was a particular driver forthe eventrsquos impact and successScience Festival Alliance (SFA) (2012) Get inspired A first look atscience festivals Retrieved from httpsciencefestivalsorgnews_itemget-inspired

Author(s) Whitney Cobb Sanlyn Buxner Stephanie ShippInstitution(s) 1 Lunar and Planetary Institute 2 McRELInternational 3 Planetary Science Institute

21910 ndash Lessons from a Train-the-TrainerProfessional Development Program The SustainableTrainer Engagement Program (STEP)The Sustainable Trainer Engagement Program (STEP) is amodified train-the-trainer professional development programbeing conducted by the Lunar and Planetary Institute (LPI) STEPhas provided two cohorts of 6-8th grade science specialists and leadteachers in the Houston region with in-depth Earth and SpaceScience (ESS) content activities and pedagogy over 15 days eachaligned with Texas science standards This project has twoover-arching goals to improve middle school ESS instruction andto create and test an innovative model for Train-the-TrainerThis poster will share details regarding STEPrsquos activities andresources program achievements and its main findings to dateSTEP is being evaluated by external evaluators at the ResearchInstitute of Texas part of the Harris County Department ofEducation External evaluation shows an increase after one year inSTEP participantsrsquo knowledge (cohort 1 showed a 10 increasecohort 2 showed a 20 increase) confidence in teaching Earth andSpace Science effectively (cohort 1 demonstrated a 10 increasecohort 2 showed a 20 increase) and confidence in preparingother teachers (cohort 1 demonstrated a 12 increase cohort 2showed a 20 increase) By September 2015 STEP participants led(or assisted in leading) approximately 40 workshops for about1800 science teachers in Texas Surveys of teachers attendingprofessional development conducted by STEP participants showvery positive responses with averages for conference workshopevaluations ranging from 36 on a 4 point scale and otherevaluations averaging from 41 to 50 on a 5 point scaleMain lessons for the team on the train-the-trainer model include alack of confidence by leaders in K-12 science education inpresenting ESS professional development difficulties in arrangingfor school or district content-specific professional development theminimal duration of most school and district professionaldevelopment sessions and uncertainties in partnerships betweenscientists and educators

Author(s) Christine Shupla Alicia Gladney HeatherDalton Keliann LaConte Jeannette Truxillo Stephanie ShippInstitution(s) 1 Harris County Department of Education 2Lunar and Planetary Institute

21911 ndash Inexpensive DAQ based physics labsQuality Data Acquisition (DAQ) based physics labs can be designed

using microcontrollers and very low cost sensors with minimal labequipment A prototype device with several sensors anddocumentation for a number of DAQ-based labs is showcased Thedevice connects to a computer through Bluetooth and uses asimple interface to control the DAQ and display real time graphsstoring the data in txt and xls formats A full device including alarger number of sensors combined with software interface anddetailed documentation would provide a high quality physics labeducation for minimal cost for instance in high schools lacking labequipment or students taking online classes An entire semesterrsquoslab course could be conducted using a single device with amanufacturing cost of under $20

Author(s) Benjamin Lewis Shane ClarkInstitution(s) 1 Mississippi State University

21912 ndash Assessment of Impact on Students andTeachers of Student-led inquiry-based planetaryscience instruction in Grades 3-8The University of Houston is in the process of developing a flexibleprogram that offers children an in-depth educational experienceculminating in the design and construction of their own modelMars rover The program is called the Mars Rover ModelCelebration (MRC) It focuses on students teachers and parents ingrades 3-8 Students design and build a model of a Mars rover tocarry out a student selected science mission on the surface of MarsA total of 195 Mars Rover teachers from the 2012-2013 2013-2014and 2014-2015 cohorts were invited to complete the Mars RoverTeacher Evaluation Survey The survey was administered onlineand could be taken at the convenience of the participant So far ~90teachers have participated with responses still coming in A total of1300 students from the 2013-2014 and 2014-2015 cohort wereinvited to submit brief self-assessments of their participation in theprogram Teachers were asked to rate their current level ofconfidence in their ability to teach specific topics within the Earthand Life Science realms as well as their confidence in their abilityto implement teaching strategies with their students The moststriking increase in this area was the reported 48 of teachers whofelt their confidence in teaching ldquoEarth and the solar system anduniverserdquo increased ldquoQuite a bitrdquo as a result of their participation inthe MRC program The vast majority of teachers (86-100) feltsomewhat to very confident in their ability to effectively implementall of the listed teaching strategies The most striking increaseswere the percentage of teachers who felt their confidence increasedldquoQuite a bitrdquo as a result of their participation in the MRC program inthe following areas ldquoGetting students interested in and curiousabout sciencerdquo (63) ldquoTeaching science as a co-inquirer withstudentsrdquo (56) and ldquoContinually find better ways to teachsciencerdquo (59) Student outcome analysis is pending correlationwith final progress reports for the participating students A keyfinding is that 354365 responding students in the 2014-2015cohort report substantial increase in science excitement owing toparticipation in the program

Author(s) Edgar Andrew Bering Coleen Carlson KennethNieser Elana SlagleInstitution(s) 1 Starfish Education 2 University of Houston

21913 ndash PUMAS The On-line journal of Math andScience Examples for Pre-College EducationPUMAS ndash ldquoPractical Uses of Math And Sciencerdquo ndash is an on-linecollection of brief examples showing how math and science topicstaught in K-12 classes can be used in interesting settings includingevery day life The examples are written primarily by scientistsengineers and other content experts having practical experiencewith the material They are aimed mainly at classroom teachers toenrich their presentation of math and science topics The goal ofPUMAS is to capture for the benefit of pre-college education theflavor of the vast experience that working scientists have withinteresting and practical uses of math and science There arecurrently over 80 examples in the PUMAS collection and they areorganized by curriculum topics and tagged with relevant gradelevels and curriculum topic benchmarks The published examplescover a wide range of subject matter from demonstrating why

2 3 1

2 12 2 1 2

1 1

2 22 1

70

summer is hot to describing the fluid dynamics of a lava lamp tocalculating the best age to collect Social Security Benefits Theexamples are available to all interested parties via the PUMAS website httppumasnasagovWe invite the community to participate in the PUMAS collectionWe seek scientists and scientific thinkers to provide innovativeexamples of practical uses for teachers to use to enrich theclassroom experience and content experts to participate inpeer-review We also seek teachers to review examples fororiginality accuracy of content clarity of presentation andgrade-level appropriateness Finally we encourage teachers tomine this rich repository for real-world examples to demonstratethe value of math in science in everyday life

Author(s) Melissa G Trainer Ralph A KahnInstitution(s) 1 NASA Goddard Space Flight Center

21914 ndash DPS Planetary Science Graduate ProgramsListing A Resource for Students and AdvisorsWe began a web page on the DPS Education site in 2013 listing allthe graduate programs we could find that can lead to a PhD with aplanetary science focus Since then the static page has evolved intoa database-driven filtered-search site It is intended to be a usefulresource for both undergraduate students and undergraduateadvisers allowing them to find and compare programs across abasic set of search criteria From the filtered list users can click onlinks to get a quick look at the database information and followlinks to the program main siteThe reason for such a list is because planetary science is a headingthat covers an extremely diverse set of disciplines The usual case isthat planetary scientists are housed in a discipline-placeddepartment so that finding them is typically noteasymdashundergraduates cannot look for a Planetary Sciencedepartment but must (somehow) know to search for them in alltheir possible places This can overwhelm even determinedundergraduate student and even many advisersWe present here the updated site and a walk-through of the basicfeatures In addition we ask for community feedback on additionalfeatures to make the system more usable for them Finally we callupon those mentoring and advising undergraduates to use thisresource and program admission chairs to continue to review theirentry and provide us with the most up-to-date informationThe URL for our site is httpdpsaasorgeducationgraduate-schools

Author(s) David R Klassen Anthony Roman BonnieMeinkeInstitution(s) 1 Rowan Univ 2 Space Telescope ScienceInstitute

21915 ndash A Guide for Scientists Interested inResearching Student OutcomesScientists spend years training in their scientific discipline and arewell versed the literature methods and innovations in their ownfield Many scientists also take on teaching responsibilities withlittle formal training in how to implement their courses or assesstheir students There is a growing body of literature of whatstudents know in space science courses and the types ofinnovations that can work to increase student learning butscientists rarely have exposure to this body of literature Forscientists who are interested in more effectively understandingwhat their students know or investigating the impact their courseshave on students there is little guidance Undertaking a moreformal study of students poses more complexities including findingrobust instruments and employing appropriate data analysisAdditionally formal research with students involves issues ofprivacy and human subjects concerns both regulated by federallawsThis poster details the important decisions and issues to considerfor both course evaluation and more formal research using acourse developed facilitated evaluated and researched by a hybridteam of scientists and science education researchers HabWorldsdesigned and implemented by a team of scientists and faculty atArizona State University has been using student data to

continually improve the course as well as conduct formal researchon studentsrsquo knowledge and attitudes in science This ongoingproject has had external funding sources to allow robustassessment not available to most instructors This is a case studyfor discussing issues that are applicable to designing and assessingall science courses Over the course of several years instructorshave refined course outcomes and learning objectives that areshared with students as a roadmap of instruction The team hassearched for appropriate tools for assessing student learning andattitudes tested them and decided which have worked or not forassessment in the course Data from this assessment has led tomany changes in the course to better meet the course goals Wewill share challenges and lessons learned in our project to assistother instructors interested in doing research on studentoutcomes

Author(s) Sanlyn R Buxner Ariel Anbar Steve Semken Chris Mead Lev Horodyskyj Viranga Perera Geoffrey Bruce David SchoumlnsteinInstitution(s) 1 Arizona State University 2 Smart Sparrow 3University of Arizona

21916 ndash Small Worlds Week An online celebration ofplanetary science using social media to reach millionsIn celebration of the many recent discoveries from New HorizonsDawn Rosetta and Cassini NASA launched Small Worlds Weekan online social media driven outreach program leveraging theinfrastructure of Sun-Earth Days that included a robust webdesign exemplary education materials hands-on fun activitiesmultimedia resources science and career highlights and aculminating social media event Each day from July 6-9 a newclass of solar system small worlds was featured on the websiteMonday-comets Tuesday-asteroids Wednesday-icy moons andThursday-dwarf planets Then on Friday July 10 nine scientistsfrom Goddard Space Flight Center Jet Propulsion LaboratoryNaval Research Laboratory and Lunar and Planetary Institutegathered online for four hours to answer questions from the publicvia Facebook and Twitter Throughout the afternoon the scientistsworked closely with a social media expert and several summerinterns to reply to inquirers and to archive their chats By allaccounts Small Worlds Week was a huge success with 37 millionpotential views of the social media QampA posts The group plans toimprove and replicate the program during the school year with amore classroom focus and then to build and extend the program tobe held every year For more information visit httpsunearthdaynasagov or catch us on Twitter nasasww

Author(s) Louis MayoInstitution(s) 1 NASAs GSFC

21917 ndash Travelers In The Night in the Old and NewMediaTravelers in the Night is a series of 2 minute audio programsbased on current research in astronomy and the space sciencesAfter more than a year of submitting ldquoTravelers In The Nightrdquo 2minute audio pieces to NPR and Community Radio stations withlimited success a parallel effort was initiated by posting the piecesas audio podcasts on Spreakercom and iTunesThe classic media dispenses programming whose content andschedule is determined by editors and station managers Riding thewave of new technology people from every demographic groupacross the globe are selecting what when and how they receiveinformation and entertainment This change is significant with thePew Research Center reporting that currently more than 60 ofFacebook and Twitter users now get their news andor links tostories from these sources What remains constant is the publicrsquosinterest in astronomy and spaceThis poster presents relevant statistics and a discussion of theinitial results of these two parallel efforts

Author(s) Albert D GrauerInstitution(s) 1 University of Arizona

21918 ndash Helping students understand planet

1 1

1 22

3 1 11 1 1 1

2

1

1

71

categories using sensing personification Jupiter aswant-to-be star Earth as want-to-be Jupiter etcStudents often in learning about the classification of planetsconsider the planets to be in strict categories (such as gas giantsand terrestrial planets) and assume that these categories aredrastically different in nature This is not the case Small objectssuch as asteroids have a weak gravitational pull such that theycannot hold an atmosphere while terrestrial planets are capable ofholding a gaseous (often transparent) atmosphere according totheir larger mass However asteroids and terrestrial planets arevery similar in composition (though not necessarily inhomogeneity due to varying presence of collisional heating duringformation) Meanwhile gas giant planets (also often referred to asJovian planets) such as Jupiter have been theorized to containsuper-sized rocky terrestrial-like planets interior to their densecloud covering Hence due then to their similar natures thecategorization of the terrestrial and gas giant planets is made notdue to fundamental differences in the nature of the planets aconcept often ill-understood by students Examining this furtherthe gas giants are planets whose masses and hence gravitationalability to condense their gases especially those close to their coreis less than those of stars wherein thermonuclear fusion initiatesThis implies that stars also have terrestrial cores (albeit likelyextremely densely packed) but the gaseous environments ofhydrogen are dense enough to start and sustain this process ofthermonuclear fusion It is proposed here that seeing planets asfundamentally related to each other in composition thoughdiffering in size allows students to better understand the variety ofplanet types AND describing these as want-to-be (or wanna-be) interms of ranking and according to a ldquosensingrdquo personification thateschews anthropomorphism animism or teleology [see A ETabor-Morris ldquoThinking in terms of sensors personification of selfas an object in physics problem solvingrdquo Physics Education 502(Feb 2015) 203-209] to assist in putting this into perspective forstudents

Author(s) Anne Tabor-MorrisInstitution(s) 1 Georgian Court University

21919 ndash New Horizons at Pluto An Overview ofEducational Activities Outreach at Fernbank ScienceCenter Atlanta Georgia (USA)We report on educational activities and associated outreach atFernbank Science Center (Atlanta GA) in conjunction with theJuly 2015 New Horizons spacecraft encounter at Pluto Onencounter day a public lecture about the dwarf planet waspresented by Georgiarsquos NASA Solar System ambassador to kick offthe arrival of the space probe at Pluto In the months following theflyby we presented a program called ldquoExploring New Horizonsrdquo inthe Science Centerrsquos Zeiss planetarium This program is a digitalfull-dome presentation about the discovery of Pluto and itssubsequent exploration ndash including an overview of the NewHorizons mission Since NASA continues to receive data from theprobe a brief update (tribute) is included at the end of eachplanetarium program that features the latest imagery and data fromthe dwarf planet We anticipate running the planetarium programthroughout the fall semester of 2015 With Pluto visible in the earlyevening autumn sky observations are possible with Centerrsquos 09 mtelescope which is open for public viewing on clear Thursday andFriday nights following the planetarium program Although Pluto issomewhat faint through the telescopes eyepiece it is visible andclearly identified within the surrounding starfield Intermittentpost-encounter lectures (Messages from the Outer Solar System)have been given on Friday evenings as well Finally due to thecontinued interest in Pluto we have developed a new outreachprogram about dwarf planets in general geared towards 4 ndash 6students

Author(s) Edward F Albin R Scott HarrisInstitution(s) 1 Fernbank Science Center

21920 ndash Partnering to Enhance Planetary ScienceEducation and Public Outreach ProgramThe Lunar and Planetary Institute (LPI) in Houston Texas utilizes

many partners to support its multi-faceted Education and PublicOutreach (EPO) program The poster will share what we havelearned about successful partnerships One portion of the programis focused on providing training and NASA content and resourcesto K-12 educators Teacher workshops are performed in severallocations per year including LPI and the Harris CountyDepartment of Education as well as across the country incooperation with other programs and NASA Planetary SciencemissionsTo serve the public LPI holds several public events per year calledSky Fest featuring activities for children telescopes for night skyviewing and a short scientist lecture For Sky Fest LPI partnerswith the NASA Johnson Space Center Astronomical Society theyprovide the telescopes and interact with members of the public asthey are viewing celestial objects International Observe the MoonNight (InOMN) is held annually and involves the same aspects asSky Fest but also includes partners from Johnson Space CenterrsquosAstromaterials Research and Exploration Science group whoprovide Apollo samples for the eventAnother audience that LPI EPO serves is the NASA PlanetaryScience EPO community Partnering efforts for the EPOcommunity include providing subject matter experts forprofessional development workshops and webinars connections togroups that work with diverse and underserved audiences andavenues to collaborate with groups such as the National ParkService and the Afterschool AllianceAdditional information about LPIrsquos EPO programs can be found athttpwwwlpiusraedueducation View a list of LPI EPOrsquospartners here httpwwwlpiusraedueducationpartners

Author(s) Heather Dalton Stephanie Shipp ChristineShupla Andrew Shaner Keliann LaConteInstitution(s) 1 Lunar and Planetary Institute

21921 ndash Contextual Student Learning throughAuthentic Asteroid Research Projects using a RoboticTelescope NetworkSkynet is a worldwide robotic telescope network operated by theUniversity of North Carolina at Chapel Hill with active observingsites on 3 continents The queue-based observation request systemis simple enough to be used by middle school students butpowerful enough to supply data for research scientists The SkynetJunior Scholars program funded by the NSF has teamed up withprofessional astronomers to engage students from middle school toundergraduates in authentic research projects from targetselection through image analysis and publication of resultsAsteroid research is a particularly fruitful area for youthcollaboration that reinforces STEM education standards and canallow students to make real contributions to scientific knowledgeeg orbit refinement through astrometric submissions to theMinor Planet Center We have created a set of projects for youth to1 Image an asteroid make a movie and post it to a gallery 2Measure the asteroidrsquos apparent motion using the Afterglow onlineimage processor and 3 Image asteroids from two or moretelescopes simultaneously to demonstrate parallax The apparentmotion and parallax projects allow students to estimate thedistance to their asteroid as if they were the discoverer of a brandnew object in the solar system Older students may take onadvanced projects such as analyzing uncertainties in asteroidorbital parameters studying impact probabilities of known objectsobserving time-sensitive targets such as Near Earth Asteroids andeven discovering brand new objects in the solar systemImages are acquired from among seven Skynet telescopes in NorthCarolina California Wisconsin Canada Australia and Chile aswell as collaborating observatories such as WestRock in ColumbusGeorgia Stone Edge in El Verano California and AstronomicalResearch Institute in Westfield Illinois

1

th th

1 1

1 11 1 1

72

Author(s) Vivian L Hoette Andrew W Puckett Tyler RLinder Sue Ann Heatherly Travis A Rector Joshua BHaislip Kate Meredith Austin L Caughey Johnny E Brown Cameron B McCarty Kevin T WhitmoreInstitution(s) 1 Astronomical Research Institute 2 ColumbusState University 3 National Radio Astronomy Observatory 4University of Alaska Anchorage 5 University of Chicago 6University of North Carolina at Chapel Hill

21922 ndash Spatial Reasoning Training Through LightCurves Of Model AsteroidsRecent research has demonstrated that spatial reasoning skillslong known to be crucial to math and science success areteachable Even short stints of training can improve spatialreasoning skills among students who lack them (Sorby et al2006) Teaching spatial reasoning is particularly valuable towomen and minorities who through societal pressure often doubttheir spatial reasoning skill (Hill et al 2010) We have designed ahands on asteroid rotation lab that provides practice in spatialreasoning tasks while building the studentrsquos understanding ofphotometry For our tool we mount a model asteroid with anyshape of our choosing on a slowly rotating motor shaft whosespeed is controlled by the experimenter To mimic an asteroid lightcurve we place the model asteroid in a dark box shine a movablelight source upon our asteroid and record the light reflected onto amoveable camera Students may then observe changes in the lightcurve that result from varying a) the speed of rotation b) the modelasteroidrsquos orientation with respect to the motor axis c) the modelasteroidrsquos shape or albedo and d) the phase angle After practicingwith our tool students are asked to pair new objects to theircorresponding light curves To correctly pair objects to their lightcurves students must imagine how light scattering off of a threedimensional rotating object is imaged on a ccd sensor plane andthen reduced to a series of points on a light curve plot Through theuse of our model asteroid the student develops confidence inspatial reasoning skills

Author(s) Julie Ziffer Paul A Nakroshis Benjamin TRudnick Maxwell J Brautigam Tyler W NelsonInstitution(s) 1 Falmouth High School 2 University ofSouthern Maine

21923 ndash 3-D Printed Asteroids for OutreachAstronomy Education3-D printed asteroids provide new opportunities for outreachastronomy education due to their low cost interactive potentialand high interest value Telescopes are expensive bulky fragileand cannot be used effectively during the day 3-D printing ofasteroids combines exciting new technology with astronomyappealing to a broader audience The printed models arescientifically accurate as their shapes have been modeled usinglight-curve inversion techniques using and occultation data toprovide a jumping off point for discussions of these advanced andexciting topics

Author(s) April RussellInstitution(s) 1 Siena College

21924 ndash An Update on the NASA Planetary ScienceDivision Research and Analysis ProgramIntroduction NASArsquos Planetary Science Division (PSD) solicitsits research and analysis (RampA) programs each year in ResearchOpportunities in Space and Earth Sciences (ROSES) Beginningwith the 2014 ROSES solicitation PSD changed the structure of theprogram elements under which the majority of planetary scienceRampA is done Major changes included the creation of five coreresearch program elements aligned with PSDrsquos strategic sciencequestions the introduction of several new RampA opportunities newsubmission requirements and a new timeline for proposalsubmissionROSES and NSPIRES ROSES contains the researchannouncements for all of SMD Submission of ROSES proposals isdone electronically via NSPIRES httpnspiresnasaprscom Wewill present further details on the proposal submission process to

help guide younger scientists Statistical trends including theaverage award size within the PSD programs selections rates andlessons learned will be presented Information on new programswill also be presented if availableReview Process and Volunteering The SARA website(httpsaranasagov) contains information on all ROSESsolicitations There is an email address (SARAnasagov) forinquiries and an area for volunteer reviewers to sign up The peerreview process is based on ScientificTechnical Merit Relevanceand Level of Effort and will be detailed within this presentationROSES 2015 submission changes All PSD programs willcontinue to use a two-step proposal submission process A Step-1proposal is required and must be submitted electronically by theStep-1 due date The Step-1 proposal should include a descriptionof the science goals and objectives to be addressed by the proposala brief description of the methodology to be used to address thescience goals and objectives and the relevance of the proposedresearch to the call submitted to

Author(s) Max Bernstein Christina Richey Jonathan RallInstitution(s) 1 NASA HQ

21925 ndash Astronomy Education amp Outreach in SouthAfricaAlthough South Africa has evolved greatly in the 20 years since theend of apartheid it remains a very divided country The highest-performing students are comparable in ability to those in the USand Europe but nearly all of these students are from privelegedAfrikaaner (European) backgrounds The vast majority of studentsin the country are native African and school standards remain verylow across the country It is common that students have notextbooks teachers have only a high school education and schoolshave no telephones and no toilets By high school graduation themajority of students have never used a web browser -- evenstudents in the capital of Johannesburg And while a few studentsare inspired by home-grown world-class projects such as theSquare Kilometer Array (SKA) and Southern African LargeTelescope (SALT) most remain unaware of their existenceDespite the poor state of education in the country students workhard are curious and desire information from the outside worldAstronomy is one subject in which students in rural Africa oftenshow exceptional interest Perhaps astronomy serves as a gatewayscience linking the physically observable world with the exotic andunknownHere I report on many visits I have made to both rural and urbanschools in South Africa during the 2013-2015 period I haveinteracted with thousands of grade 7-12 students at dozens ofschools as well as taught students who graduated from this systemand enrolled in local universities I will present an assessment ofthe state of science education in South Africa as well as a fewbroader suggestions for how scientists and educators in developedcountries can best make an impact in Southern Africa

Author(s) Henry B ThroopInstitution(s) 1 PSI

300 ndash Titans Atmosphere and Surface30001 ndash Monstrous Ice Cloud System in TitansPresent South Polar StratosphereDuring southern autumn when sunlight was still availableCassinis Imaging Science Subsystem discovered a cloud around300 km near Titans south pole (West R A et al AASDPSAbstracts 45 30503 2013) the cloud was later determined byCassinis Visible and InfraRed Mapping Spectrometer to containHCN ice (de Kok et al Nature 514 pp 65-67 2014) This cloudhas proven to be only the tip of an extensive ice cloud systemcontained in Titans south polar stratosphere as seen through thenight-vision goggles of Cassinis Composite InfraRed Spectrometer(CIRS) As the sun sets and the gloom of southern winterapproaches evidence is beginning to accumulate from CIRS far-IRspectra that a massive system of nitrile ice clouds is developing inTitans south polar stratosphere Even during the depths of

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northern winter nothing like the strength of this southern systemwas evident in corresponding north polar regionsFrom the long slant paths that are available from limb-viewingCIRS far-IR spectra we have the first definitive detection of the νband of cyanoacetylene (HC N) ice in Titanrsquos south polarstratosphere In addition we also see a strong blend of nitrile icelattice vibration features around 160 cm From these data we areable to derive ice abundances The most prominent (and stillchemically unidentified) ice emission feature the Haystack (at220 cm ) is also observed We establish the vertical distributionsof the ice cloud systems associated with both the 160 cm featureand the Haystack The ultimate aim is to refine the physical andpossibly the chemical relationships between the twoTransmittance thin film spectra of nitrile ice mixtures obtained inour Spectroscopy for Planetary ICes Environments (SPICE)laboratory are used to support these analyses

Author(s) Carrie Anderson Robert Samuelson JasonMcLain Richard Achterberg F Michael Flasar Stefanie MilamInstitution(s) 1 NASA GSFC 2 University of Maryland

30002 ndash Condensation of trace species to form icelayers in Titans stratosphereIn addition to the organic haze particles produced photochemicallyin Titans upper atmosphere a number of trace gases are alsocreated These hydrocarbon and nitrile species include C H C H C H HCN HC N C H CN and many more While bothVoyager and Cassini observations have found evidence for ices (egC N HCN) in the atmosphere above Titans poles these speciesare also likely to condense at other latitudes forming optically thinice layers in the stratosphere A series of simulations have beenconducted using Titan CARMA a 1-D microphysics and radiativetransfer model to explore cloud particle formation with ~20 ofTitans trace hydrocarbon and nitrile gases These species reachtheir condensation temperatures between 60 and 110 km Mostcondense solely as ices however C H will condense first near 70km as a liquid and then freeze as the droplets descend toward thesurface C H and C H join CH as a liquid at Titans surfaceMany ices have long condensation timescales resulting in particleradii ~1 μm or less Several (including HCN C H C H ) willgrow 10-50 times larger Expected condensation altitudes andparticle sizes will be presented as well as the implications for theoptical properties of Titans stratospheric aerosol particlesThis work was supported by the NASA Outer Planets Researchprogram

Author(s) Erika L BarthInstitution(s) 1 Southwest Research Inst

30003 ndash Wind Shear May Produce Long-Lived Stormsand Squall Lines on TitanThe impact of CAPE and wind shear on storms in a Titan-likeenvironment are explored through numerical simulationNumerical modeling indicates that both large-scale shear andCAPE environment control the dynamics of the clouds Thisresponse to the large-scale environment is analogous to thebehavior of deep convective clouds on Earth The balance betweenshear and CAPE as expressed through the bulk RichardsonNumber (N ) is a good indicator of the response of a storm to itsenvironment Large N results in short-lived single cell storms(Figure 1) As shear increases for a given CAPE and N decreasesthe storms transition to a multicellular regime Multicellularstorms are longer-lived and are characterized by a downdraftgenerated cold pool that interacts with the background shearvorticity to initiate cells along the leading edge of the storm gustfront (Figure 2) Very long-lived storms (gt24 hours) propagatingfor 1000 km or more might be possible The most intensemulticellular systems simulated in this study behave similar toterrestrial squall lines and very long-lived storms (gt24 hours)propagating for 1000 km or more might be possible Cloudoutbursts and linear cloud features observed from ground andCassini may be the result of these organized storm systemsVarying amounts of shear in the Titan environment might explainthe variety of convective cloud expressions identified in Cassini

orbiter and ground-based observations The resulting distributionand magnitude of precipitation as well as surface winds associatedwith storms have implications on the formation of fluvial andaeolian features including dunes and on the exchange of methanewith the surface and lakes

Author(s) Scot CR Rafkin Erika BarthInstitution(s) 1 SWRI

30004 ndash Asymmetric lake distribution on Titanmediated by methane transport due to atmosphericeddiesThe observed north-south asymmetry in the distribution of Titansseas and lakes has been proposed to be a consequence of orbitalforcing affecting Titans hydrologic cycle as in the present thenorthern summer is longer but milder than its southerncounterpart Though recent general circulation models havesimulated asymmetrical surface liquid distributions themechanism that generates this asymmetry has not been explainedIn this work we compare axisymmetric and three-dimensionalsimulations of Titans atmospheric circulation with the TitanAtmospheric Model (TAM) [Lora et al 2015 Icarus 250] toinvestigate the transport of moisture by the atmosphere Asignificant hemispheric asymmetry only develops in the latter caseand we demonstrate that equatorward transport by high-latitudebaroclinic eddies is responsible Eddies transport moisture fromthe high latitudes into the low and midlatitude cross-equatorialmean meridional circulation producing an atmospheric bucketbrigade The moisture transport by eddies is more intense in thesouth than in the north as a consequence of the orbital forcing andtherefore the result is net northward transport of methaneexplaining the surface buildup in the north

Author(s) Juan M Lora Jonathan L MitchellInstitution(s) 1 University of California

30005 ndash Seasonal Surface Temperature Changes onTitanThe Composite Infrared Spectrometer (CIRS) on Cassini has beenmeasuring surface brightness temperatures on Titan since 2004(Jennings et al 2011 Cottini et al 2012 Tan et al 2015) Radiationfrom the surface reaches space through a window of minimumopacity in Titanrsquos atmosphere near 19 microns wavelength Wemapped surface temperatures in five time periods each about 2years centered on solar longitudes Ls = 313deg 335deg 0deg 28deg and 53degdegrees Using zonally-averaged spectra binned in 10-degreelatitude intervals we clearly see the seasonal progression of thepole-to-pole temperature distribution Whereas peak temperaturesin the vicinity of the Equator have been close to 94 K throughoutthe Cassini mission early in the mission temperatures at the NorthPole were as low as 90 K and at the South Pole were 92 K Late inthe mission the pattern has reversed 92 K in the north and 90 K inthe south Over 2005 to 2014 the peak temperature moved inlatitude from about 15 S to 15 N We estimate a seasonal lag of 02Titan month In 2010 the temperature distribution wasapproximately symmetric north and south agreeing with Voyager 1from one Titan year earlier The surface temperatures followclosely the predictions of Tokano (2005) Our measurements mayindicate a lower thermal inertia in the south than in the northJennings DE et al ApJ Lett 737 L15 (2011)Cottini V et al 2012 Planet Space Sci 60 62 (2012)Tan S P et al Icarus 250 64 (2015)Tokano T Icarus 204 619 (2005)

Author(s) Donald E Jennings Valeria Cottini Conor ANixon Athena Coustenis Tetsuya TokanoInstitution(s) 1 Department of Astronomy University ofMaryland 2 LESIA Paris Obs PSL-Research Univ CNRS UnivParis 06 Sorbonne Univ Univ Paris-Diderot 3 NASA GoddardSpace Flight Center 4 Universitaumlt zu Koumlln

30006 ndash Titanrsquos mid-latitude surface regions withCassini VIMS and RADARThe Cassini-Huygens mission instruments have revealed Titan to

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have a complex and dynamic atmosphere and surface Data fromthe remote sensing instruments have shown the presence ofdiverse surface terrains in terms of morphology and compositionsuggesting both exogenic and endogenic processes [1] We defineboth the surface and atmospheric contributions in the VIMSspectro-imaging data by use of a radiative transfer code in thenear-IR range [2] To complement this dataset the Cassini RADARinstrument provides additional information on the surfacemorphology from which valuable geological interpretations can beobtained [3] We examine the origin of key Titan terrains coveringthe mid-latitude zones extending from 50ordmN to 50ordmS The differentgeological terrains we investigate include mountains plainslabyrinths craters dune fields and possible cryovolcanic andorevaporite features We have found that the labyrinth terrains andthe undifferentiated plains seem to consist of a very similar if notthe same material while the different types of plains showcompositional variations [3] The processes most likely linked totheir formation are aeolian fluvial sedimentary lacustrine inaddition to the deposition of atmospheric products though theprocess of photolysis and sedimentation of organics We show thattemporal variations of surface albedo exist for two of the candidatecryovolcanic regions The surface albedo variations together withthe presence of volcanic-like morphological features suggest thatthe active regions are possibly related to the deep interior possiblyvia cryovolcanism processes (with important implications for thesatellitersquos astrobiological potential) as also indicated by new interiorstructure models of Titan and corresponding calculations of thespatial pattern of maximum tidal stresses [4] However anexplanation attributed to exogenic processes is also possible [5]We will report on results from our most recent research on thesurface properties of Titan[1] Solomonidou et al Icarus accepted [2] Solomonidou et al JGR119 1729ndash1747 2014 [3] Lopes et al Icarus in rev [4] Sohl et alJGR 119 1013-1036 2014 [5] Moore amp Pappalardo Icarus 212790-806 2011

Author(s) Anezina Solomonidou Rosaly MC Lopes Athena Coustenis Michael Malaska Sebastien Rodriguez Luca Maltagliati Pierre Drossart Michael Janssen KennethLawrence Ralf Jaumann Frank Sohl Katrin Stephan RobertH Brown Emmanuel Bratsolis Christos MatsoukasInstitution(s) 1 Department of Physics National andKapodistrian University of Athens 2 DLR Institute of PlanetaryResearch 3 Laboratoire AIM Universiteacute Paris Diderot Paris7CNRSCEA-Saclay DSMIRFUSAp 4 LESIA - Observatoire deParis CNRS UPMC Univ Paris 06 Univ Paris-Diderot 5 Lunarand Planetary Laboratory University of Arizona 6 NASA JetPropulsion Laboratory California Institute of Technology

30007 ndash Using the VIMS Dataset to UnderstandTitanrsquos Hydrologic Cycle Through CloudCharacterizationAlong with Earth Titan is the only body in our Solar System topossess an active hydrologic cycle Monitoring how Titanrsquosmethane-based hydrologic cycle varies with season over Saturnrsquos297-year orbital period is essential for understanding its climatesystemUsing a newly developed radiative transfer pipeline with updatedHITRAN methane line parameters we will present an ongoinganalysis of the known cloud observations in the VIMS datasetAlthough much work has gone into finding clouds in this datasetlittle work has been done on understanding the characteristics ofthese clouds barring a handful of individual analyses Our pipelineallows for fast determination of these cloud characteristicsincluding optical depth altitude and mean drop size VIMS offerstwo advantages providing consecutive observations of individualcloud systems to help diagnose formation mechanism andproviding a decade long dataset to track seasonal variations likethose observed in cloud frequency and location Characterizingclouds allows for an understanding of seasonally varying formationmechanisms traces Titanrsquos atmospheric methane content acrossseasonal timescales and can indicate clouds that could potentiallyhave precipitated to provide context for interpreting observedsurface features

We will also present an update on an ongoing ground based- cloudmonitoring campaign This campaign begun in April 2014 has(nearly) continually monitored Titan on a variety of telescopes forthe past 15 years To date no cloud activity has been observeddespite the variety in observation techniques that multipletelescopes allow This is interesting because large cloud outburstswere observed during the equivalent point in southern summerand suggest a dichotomy in the seasonal dynamics of Titanrsquosatmosphere Understanding when and with what frequency cloudsbegin to form in the north is crucial to understanding Titanrsquoshydrologic cycle on seasonal time scales

Author(s) Paul Corlies Alexander G Hayes SebastienRodriguez Mate Adamkovics Patricio Rojo Elizabeth PTurtleInstitution(s) 1 Cornell University 2 John Hopkins UnivApplied Physics Laboratory 3 Universidad de Chile 4 UniversiteParis Diderot - Paris 7 5 University of California Berkeley

30008 ndash Hydrology-based understanding of OntarioLacus in Titans south poleOntario Lacus is the largest presently filled lake at the south pole ofTitan Many other large basins in south pole exist at lowerelevations than Ontario Lacus but are currently empty To find outwhat sets Ontario apart from those empty basins we have carried adetailed hydrological assessment of Ontario Lacus Topography ofthe region as derived from Cassini RADAR altimetry was used todetermine the catchment area of Ontario Lacus We could map theareal extent of catchments as far as southern mid-latitudes Cloudsin southern mid and high latitudes have been observed by CassiniVIMS which indicate possible precipitation in those regionsPrecipitation in southern mid-latitudes coupled with the largecatchment areas of Ontario Lacus could be the reason behind itbeing filled Our mass conservation calculations indicate that ifrunoff was the only contributor to the lake volume then the lakemight be filled within one Titan year (295 Earth years) in entiretyWe also observe a non-linear relationship between the longestidentifiable stream and the catchment area (Hacks Law) which isconsistent with terrestrial hydrological systems and may help infurther interpretation of the hydrology of Ontario Lacus

Author(s) Rajani D Dhingra Jason W Barnes Brian JYanites Randolph L KirkInstitution(s) 1 Astrogeology Science Center United StatesGeological Survey 2 University of Idaho

30009 ndash Near Infrared Spectroscopy of LiquidHydrocarbon Mixtures for Understanding theComposition of Titanrsquos LakesThe presence of ethane and methane lakes on Titan was confirmedby the Cassini Visible and Infrared Mapping Spectrometer (VIMS)data in 2008 and has been investigated in further detail by theCassini radar instrument (Brown et al 2008 Pailloue et al 2008)Modeled compositions suggest that the lakes are predominantlyliquid ethane with liquid methane propane and butane howeverpure liquid methane lakes (such as Ligeia Mare) may also bepresent (Cordier et al 2009 Mastrogiuseppe et al 2014) Wepresent a proof-of-concept instrument consisting of a nearinfrared (NIR) spectrometer with a fiber optic probe in order toconduct non-invasive analyses of cryogenic fluids on planetarybodies To determine the utility of spectroscopy for in-situ studieswe collected transmission spectra of hydrocarbon mixtures puremethane and ethane endmembers and nitrogen-saturatedhydrocarbons in the NIR region between 900 to 2500 nm liquidhydrocarbons were measured in a dewar filled with liquid nitrogencontained within a glove bag pumped with gaseous nitrogen at atotal oxygen concentration of lt 01 The resultant spectracontained key absorption features that allowed us to determine therelative abundances of each endmember and the effectstemperature and dissolved nitrogen based on the changes in peakintensity Peak intensity as well as integrated absorbancefull-width half-maximum and peak location were calculated usinga multi-peak fitting algorithm we also adopted a simple linearmixing model which used pure ethane and methane spectra as well

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as the measured mixtures to calculate the linear coefficients ofeach endmember within the mixture Resultant plots of changes inpeak intensity with temperature (for methane) peak intensity withmole fraction of methane (or ethane) and comparisons of themodeled linear coefficients with the mole fraction of methane (orethane) added will yield useful data on how methane ethane anddissolved nitrogen mix Ideally this information can also be used tobetter validate theoretical models on hydrocarbon mixing andnitrogen solubility providing insight on the loss tangentmeasurements of Titanrsquos lakes obtained by Mastrogiuseppe fromradar altimetry data

Author(s) Bryne Hadnott Robert Hodyss Morgan Cable Tuan Vu Alexander HayesInstitution(s) 1 Cornell University 2 Jet PropulsionLaboratory

301 ndash Asteroid Surveys See and Say30101 ndash NEOWISE Reactivation Mission Year OnePreliminary Asteroid Diameters and AlbedosThe infrared NEOWISE project (Mainzer et al 2011a) hasmeasured diameters and albedos for sim20 of the known asteroidpopulation the majority of these measurements to date (Mainzeret al 2011b 2012 2015 Masiero et al 2011 2012 Grav et al 20112012a Bauer et al 2013) Here we expand the number of asteroidscharacterized by NEOWISE deriving diameters and albedos for7959 asteroids detected between December 13 2013 andDecember 13 2014 during the first year of the Reactivationmission 7758 are Main Belt or Mars-crossing asteroids 17 ofthese objects have not been previously characterized using WISEor NEOWISE thermal measurements Diameters are determined toan accuracy of ~20 or better If good-quality H magnitudes areavailable albedos can be determined to within ~40 or better

Author(s) Carolyn Nugent A Mainzer J R Masiero JBauer R M Cutri T Grav E Kramer S Sonnett RStevenson E WrightInstitution(s) 1 CaltechIPAC 2 JPL 3 Planetary ScienceInstitute 4 Self 5 UCLA

30102 ndash NEOSurvey An Spitzer Exploration ScienceSurvey of Near Earth Object PropertiesWe are carrying out a Spitzer Cycle 11 (2015-2016) ExplorationScience program entitled NEOSurvey in which we are observing597 known Near Earth Objects (NEOs) in 710 hours of observingtime Each object is observed at 45 microns The primary goal ofour program is to use a thermal model to create a catalog of NEOdiameters and albedos that can be used for a wide range of sciencegoals From this catalog we will derive the size distribution of NEOsdown to 100 meters and measure the compositional distribution ofNEOs as a function of size We include in our target list only objectsthat are too faint to be detected by NEOWISE This catalog istherefore highly complementary to existing and forthcomingsamples and will complete a database of diameters and albedos fornearly 2000 NEOs (including results from our previous Spitzerprogram ExploreNEOs as well as objects observed by NEOWISE)We will present the status of the program and results to date somenine months into the execution of the program All observationaland model results are published immediately online atnearearthobjectsnauedu Support for this work is provided by theSpitzer Science Center

Author(s) David E Trilling Michael Mommert JosephHora Steve Chesley Joshua Emery Giovanni Fazio AlanHarris Michael Mueller Howard SmithInstitution(s) 1 German Aerospace Centre (DLR) 2 Harvard-Smithsonian Center for Astrophysics 3 NASAJPL 4 NetherlandsInstitute for Space Research 5 Northern Arizona University 6 UTennessee Knoxville

30103 ndash Main-Belt Source Regions for PotentiallyHazardous Near-Earth Asteroids and Sample Return

TargetsSpectroscopic and taxonomic information is now available for morethan 1000 near-Earth objects (NEOs) thanks in large measure tothe NASA IRTF long-term NEO spectral reconnaissance programwe call the MIT-Hawaii Near-Earth Object Spectroscopic Survey(MITHNEOS) [1] This sample comprises about 10 of the totalNEO population including Potentially Hazardous Asteroids(PHAs) and finds that all defined main-belt asteroid classes arealso present within the near-Earth population Using this largestavailable NEO dataset and dynamic source region models (such as[2]) we will present new results on the provenance of PHAs sourceregions for each of the asteroid taxonomic classes and pinpointsources for major meteorite classes such as H L and LL ordinarychondrites In finding these correlations we find that source regionsignatures for B- C- and Cg-type NEOs include Jupiter familycomets further adding interest to the sampling of these classes byimpending missions [3 4] This work is supported by the NationalScience Foundation Grant 0907766 and NASA GrantNNX10AG27G[1] Tokunaga A et al (2006) BAAS 38 5907 [2] Bottke WF etal (2002) Icarus 156 399 [3] Lauretta D S et al (2015) MAPS50 834 [4] Abe M et al (2012) 39th COSPAR AbstractH02-7-12

Author(s) Richard P Binzel F E DeMeo B J Burt DPolishook T H Burbine N Moskovitz S J Bus ATokunaga M BirlanInstitution(s) 1 Lowell Observatory 2 MIT 3 ParisObservatory 4 University Hawaii

30104 ndash The Bias-Corrected Taxonomic Distributionof Mission-Accessible Small Near-Earth ObjectsAlthough they are thought to compose the majority of theNear-Earth object (NEO) population the small (d lt 1 km)near-Earth asteroids (NEAs) have not yet been studied asthoroughly as their larger cousins Sub-kilometer objects areamongst the most abundant newly discovered NEOs and are oftentargets of opportunity observable for only a few days to weeks aftertheir discovery Even at their brightest (V ~ 18) these asteroids arefaint enough that they must be observed with large ground-basedtelescopesThe Mission Accessible Near-Earth Object Survey (MANOS) beganin August 2013 as a multi-year physical characterization surveythat was awarded survey status by NOAO MANOS will targetseveral hundred mission-accessible NEOs across visible andnear-infrared wavelengths ultimately providing a comprehensivecatalog of physical properties (astrometry light curves spectra)Fifty-seven small mission-accessible NEAs were observed betweenmid 2013 and mid 2015 using GMOS at Gemini North amp Southobservatories as well as the DeVeny spectrograph at LowellObservatorys Discovery Channel Telescope Archival data of 43objects from the MIT-UH-IRTF Joint Campaign for NEO SpectralReconnaissance (PI R Binzel) were also used Taxonomicclassifications were obtained by fitting our spectra to the meanreflectance spectra of the Bus asteroid taxonomy (Bus amp Binzel2002) Small NEAs are the likely progenitors of meteorites animproved understanding of the abundance of meteorite parentbody types in the NEO population improves understanding of howthe two populations are related as well as the biases Earthsatmosphere imposes upon the meteorite collectionWe present classifications for these objects as well as results for thedebiased distribution of taxa(as a proxy for composition) as a function of object size andcompare to the observed fractions of ordinary chondritemeteorites and asteroids with d gt 1 km Amongst the smallestNEOs we find an unexpected distribution of taxonomic types thatdiffers from both large NEOs and meteoritesWe acknowledge funding support from NASA NEOO grant numberNNX14AN82G

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Author(s) Mary L Hinkle Nicholas Moskovitz DavidTrilling Richard P Binzel Cristina Thomas Eric Christensen Francesca DeMeo Michael J Person David Polishook MarkWillmanInstitution(s) 1 Catalina Sky Survey 2 Harvard-SmithsonianCenter for Astrophysics 3 Institute for Astronomy - U Hawaii 4Lowell Observatory 5 MIT 6 Northern Arizona University 7PSI 8 Weizmann Institute of Science

30105 ndash Constraining the shape distribution andbinary fractions of asteroids observed by NEOWISEKnowing the shape distribution of an asteroid population givesclues to its collisional and dynamical history Constraining lightcurve amplitudes (brightness variations) offers a first-orderapproximation to the shape distribution provided all asteroids inthe distribution were subject to the same observing biasesAsteroids observed by the NEOWISE space mission at roughly thesame heliocentric distances have essentially the same observingbiases and can therefore be inter-compared We used the archivalNEOWISE photometry of a statistically significant sample of JovianTrojans Hildas and Main belt asteroids to compare the amplitude(and by proxy shape) distributions of L4 vs L5 Trojans Trojans vsHildas of the same size range and several subpopulations of Mainbelt asteroidsFor asteroids with near-fluid rubble pile structures very large lightcurve amplitudes can only be explained by close or contact binarysystems offering the potential to catalog and characterize binarieswithin a population and gleaning more information on itsdynamical evolution Because the structure of most asteroids is notknown to a high confidence level objects with very high light curveamplitudes can only be considered candidate binaries In Sonnettet al (2015) we identified several binary candidates in the JovianTrojan and Hilda populations We have since been conducting afollow-up campaign to obtain densely sampled light curves of thebinary candidates to allow detailed shape and binary modelinghelping identify true binaries Here we present preliminary resultsfrom the follow-up campaign including rotation propertiesThis research was carried out at the Jet Propulsion Laboratory(JPL) California Institute of Technology (CalTech) under acontract with the National Aeronautics and Space Administration(NASA) and was supported by the NASA Postdoctoral Program atJPL We make use of data products from the Wide-field InfraredSurvey Explorer which is a joint project of the University ofCalifornia Los Angeles and JPLCalTech funded by NASA Thispublication also makes use of data products from NEOWISEwhich is a project of JPLCalTech funded by the Planetary ScienceDivision of NASA

Author(s) Sarah M Sonnett Amy Mainzer Tommy Grav Joseph Masiero James Bauer Pierre Vernazza Judit GyorgyeyRies Emily KramerInstitution(s) 1 Jet Propulsion Laboratory 2 LaboratoiredAstrophysique de Marseille 3 Planetary Science Institute 4University of Texas at Austin

30106 ndash Hilda Asteroid Compositions as anObservational Test of Giant Planet Migration ModelsMultiple lines of evidence indicate that planetary migration is a keypart of the evolution of planetary systems Planetary migrationmodels of the solar system suggest that the Jupiter Trojan andHilda stable resonances were repopulated during giant planetmigration We have completed a 4-year multi-epoch photomtericmulti-color survey of Hilda asteroids in order to determineindividual object composition The colors of ~500 Hildas are nowknown a factor of 3 increase in objects with determinedcompositions compared to the start of our observations We reportthe results of our survey in the context of the predictions fromcurrent dynamical migration models identify the modelinconsistent with the compositional results and address futureobservational data that is required in addition to Hilda asteroidcompositions to validate the Nice and Grand Tack modelsThis work supported by the University of MinnesotaUndergraduate Research Scholarship Program and NASAPlanetary Astronomy Grant NNX13AJ11G

Author(s) Erin L Ryan Charles E Woodward BenjaminSharkey Keith S NollInstitution(s) 1 Minnesota Institute for AstrophysicsUniversity of Minnesota 2 NASA GSFC 3 University ofMaryland

30107 ndash The Pan-STARRS search for Near EarthObjectsThe two Pan-STARRS telescopes located on Haleakala Hawaii are18-meter diameter telescopes equipped with 14 Gigapixel camerasthat deliver 7 square degree fields of view The first telescopePan-STARRS1 (PS1) has been conducting a survey for Near-EarthObjects The second telescope Pan-STARRS2 (PS2) is nearingcompletion The telescope was commissioned using an incompletefocal plane with only 18 good detectors (60 required) The camerais presently being upgraded and will be operated from October2015 with 60 detectors (some engineering grade) A final upgradeto the camera in early 2016 will make the telescope fullyoperationalThe two telescopes survey much of the sky accessible fromHaleakala multiple times each lunation The area surveyed rangesfrom +90 degrees in the north down to -475 degrees declination inthe south The ldquosweet spotsrdquo close to the Sun have been productivein discovery of large objectsThe PS1 survey is becoming more mature and productive havingdiscovered more than half of all NEOs in 2015 to date and morethan 60 of the larger NEOs and PHAs discovered in 2015 BothPS1 and PS2 deliver excellent astrometry and photometry PS1continues to discover a significant number of large (gt 1km) NEOsPS1 has become the leading discover of comets discovering morethan half of the new comets in both 2014 and 2015In good weather conditions the discovery rate of NEO candidatesby PS1 overwhelms the external NEO followup resourcesparticularly for fainter NEOs As a result we needed to repeat fieldsto recover NEO candidates As PS2 matures with a complete focalplane and when the G96 camera upgrade is complete thecombination of these three telescopes will facilitate a higher NEOdiscovery rate a better census of the NEOs in the sky and betterorbits for NEOs This will in turn lead to a better understanding ofthe size and orbit distribution of NEOs The Pan-STARRS NEOsurvey is also likely to discover asteroids suitable for the NASAasteroid retrieval missionSome early science highlights from the Pan-STARRS survey will bediscussed

Author(s) Richard J Wainscoat Kenneth Chambers EvaLilly Robert Weryk Serge Chastel Larry Denneau MarcoMicheliInstitution(s) 1 ESA NEO Coordination Centre 2 Univ ofHawaii

30108 ndash Olivine-rich asteroids in the main asteroidbeltOlivine-dominated asteroids classified as A-types withnear-infrared spectral measurements are largely thought to be themantle remnants of disrupted differentiated small bodies TheseA-type asteroids hold clues to asteroid differentiation and to thecollisional history of those differentiated bodies Preliminarystudies of the abundance and distribution of A-type asteroids wereperformed by Carvano et al (2010) and DeMeo amp Carry (20132014) using the Sloan Digital Sky Survey (SDSS) To confidentlyidentify these olivine-dominated A-type asteroids howevernear-infrared spectral measurements are needed to identify thedistinct broad and deep 1-micron olivine absorption feature Usingthe Sloan Digital Sky Survey Moving Object Catalog to select A-typeasteroid candidates we have performed a near-infrared spectralsurvey of over 70 asteroids with SpeX on the IRTF We present theabundance and distribution of A-type asteroids throughout themain asteroid belt and compare these results with similar surveysfor basalt-rich V-type asteroids (eg Moskovitz et al 2008) Thiswork is supported by NASA under grant number NNX12AL26Gissued through the Planetary Astronomy Program

6 46 5 7 1

2 5 83

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4 1

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77

Author(s) Francesca E DeMeo David Polishook BenoitCarry Nick Moskovitz Brian Burt Rick BinzelInstitution(s) 1 Lowell Observatory 2 Massachusetts Instituteof Technology 3 Nice Observatory

30109 ndash Revealing Secrets of Triple Asteroid Systemswith SPHEREA multiple-asteroid system provides otherwise unattainableinformation about the intrinsic properties of the system itself aswell as its formation and evolution Comparative spectroscopy andimaging of two large multiple main-belt asteroids (93) Minervaand (130) Elektra were performed using the newly commissionedSpectro-Polarimetric High-contrast Exoplanet Researchinstrument (SPHERE) on ESOs 82-m VLT A new moon (S2014(130) 1) of the known binary asteroid (130) Elektra wasdiscovered based on the SPHERE observations making (130)Elektra the sixth triple system detected in the asteroid belt We willpresent the component-resolved near infrared spectra from 09 to16 micron of the Minerva and the Elektra triple systems We willalso present the orbital solution and the dynamical simulations onthe two moons of (130) Elektra

Author(s) Bin Yang Zahed Wahhaj Laurene Beauvalet Franck Marchis Christophe Dumas Michaeumll MarssetInstitution(s) 1 Carl Sagan Center of the SETI Institute 2European Southern Observatory 3 Observatoacuterio Nacional Rio deJaneiro 4 TMT International Observatory

302 ndash Formation of Planets Satellites andSmall Bodies30201 ndash The collisional evolution of chondritic parentbodiesMost meteorites are fragments form recent collisions in theasteroid belt The collision speed between two objects of theasteroid belt is given by the eccentricity and inclination of theirrespective Keplerian orbits Typical values are on the order of a fewkm s In such a hyper-velocity collision the smaller collisionpartner (projectile) is destroyed whereas depending on the massratio of the colliding objects a crater on the larger body (target) isformed or the target is entirely destroyed too The present sizedistribution of the asteroid belt suggests that an asteroid with 100km radius is encountered ~10 times during the lifetime of theSolar System by objects larger than 10 cm in radius the formedcraters cover the surface of the asteroid about 100 timesWe will present a numerical study that simulates the statisticalbombardment on an asteroidal surface and tracks the resultingmorphological changes of the parent body due to the formation ofcraters the compaction of the material beneath the craters as wellas the formation of a regolith layer The crater ejecta from recentimpacts on a consolidated asteroid are then compared to the knownmeteorites particularly concerning the distribution of shock stagesComparing the compaction of ejected material from the simulatedcollisions that occurred during the last 20 Myrs which is the meancosmic ray exposure age of meteorites with shock stages ofmeteorites we find that meteorites most likely stem from smallerparent bodies that do not have a significant regolith layer Forlarger objects that inevitably accrete regolith layers a prediction ofthe thickness depending on the largest visible crater can be madeAdditionally we compare the crater distribution of an initially 100km (radius) large object with a shape model of asteroid (21)Lutetia assuming it to be initially formed spherical with a radiusthat is equal to its longest present ellipsoid length and find areasonable agreement Following our study predictions of theporosity of the surface and the interior of the asteroid as well as theshock stages of ejected material can be made

Author(s) Juumlrgen Blum Eike Beitz Mirta Gabriela ParisiInstitution(s) 1 Instituto Argentino de Radioastronomia 2 TUBraunschweig

30202D ndash Planetesimal Formation - Collisions ofDecimeter Ice and Dust

The early stages (from microm to mm) as well as the late stages (fromkm to planet size) of planet formation are quite well understoodThe intermediate stage of planetesimal formation is notunderstood in detail yet Several processes such as bouncing orradial drift can potentially stall growth beyond the millimeter orcentimeter size rangeThe collision dynamics of decimeter bodies are important inplanetesimal formation models They are interesting forcoagulation models as radial drift towards the central star becomessevere at sizes of decimeter to meter But they are also crucial forgravitational instability models because concentrationmechanisms are believed to be strongest for decimeter bodiesWe performed various collision experiments with decimeter as wellas centimeter bodies made up of both silicate dust and water iceWe investigated threshold conditions such as the threshold tofragmentation which are especially interesting for the coagulationmodelsThough mutual collisions might lead to bouncing or evenfragmentation already at velocities that are much lower thanrelative velocities expected in PPDs growth beyond decimeter sizesis still possible Decimeter bodies start to decouple from to thesurrounding gas which results in relative velocities to smallerbodies of several ms In such collisions of bodies of different sizesthe bigger body can gain mass This can be by direct mass transferfrom the smaller body Here the accretion efficiency is a crucialparameter Mass can also be transferred through gas-drivenre-accretion of fragments of the smaller body which are producedin the collision The velocity and size distribution of the ejectedfragments are significant for re-accretion

Author(s) Johannes Deckers Jens Teiser Gerhard WurmInstitution(s) 1 Universitaumlt Duisburg-Essen

30203 ndash Icy Collisions ndash Planet Building beyond thesnowlineCollisions of small icy and dust particles beyond the ldquosnow-linerdquo area key step in planet formation Whilst the physical forces thatunderpin the aggregation of the smallest grains (van der Waals)and the largest planetessimals (gravity) are well understood theprocesses involving mm ndash cm sized particles remain a mysteryIn a unique set of experiments we investigated low velocitycollisions of dust and icy particles in this size range undermicrogravity conditions ndash utilizing parabolic flight (eg Salter2009 Hill 2015 (a) amp (b)) Experiments were performed atcryogenic temperatures (below 140 K) for icy aggregates andambient as well as cryogenic temperatures (80 ndash 220 K) for dustaggregatesThe kinetic analysis of the observed collisions of different aggregatetypes in different shapes and sizes revealed astonishing results ndash asthe collisional properties of all investigated particles differ stronglyfrom the usual assumptions in models of planet formationHere we present a summary of the results on the collisions of icyparticles as well as first results on the collisions of dust aggregatesFocus will be on the coefficient of restitution which measures theloss of translational energy in bouncing collisions and is a keyparameter in models of planet formation

Author(s) Sabrina Gaertner Catherine Hill DanielHeisselmann Juergen Blum Helen FraserInstitution(s) 1 Technische Universitaet Braunschweig 2 TheOpen University

30204 ndash Forming the Terrestrial Planets from anAnnulusWe present results from the growth of planets directly fromplanetsimals initially constrained to a narrow annulus between07-10 AU The simulations examine the idea that the EarthMarsmass ratio can be explained when the planets form from atruncated disk with an outer edge at 10 AU Using the Lagrangiancode known as LIPAD we present results on the role offragmentation and the effects of interactions with the gas-disk onthe evolution of a large number of planetesimals as they grow toplanetsIn particular we report on simulations where initially the solids in

2 23 1 2 2

2 2 31 4 2

-1

14

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78

the disk are planetesimals with the same initial radii (varied fromrun to run between 3 and 300 km) with and withoutfragmentation and with and without the effects of a gas-disk Thepresence of a gas disk strongly changes the outcomes of the firstfew million years of growth keeping accretion rates high throughlow relative velocity collisions Meanwhile fragmention processescan produce small particles that by way of dynamical friction canprovide some of the same dynamical affects as the gas-disk -though with the side effect of mass loss due to the grind of particlesto small sizes and subsequent drift out of the annulusIn sum the final planetary systems sometimes produceMars-analogs with appropriately small mass but due to dodiffusive spreading rather than violent scattering However theyrarely produce objects as massive as Earth and Venus do to thesame effect

Author(s) Harold F Levison Kevin WalshInstitution(s) 1 Southwest Research Inst

30205 ndash Planetsimals to Planets - RevisitingTerrestrial Planet FormationNearly all previous models of terrestrial planet formation focus oneither a short span of time or a narrow sliver of the disk tounderstand a specific mode of growth The final stages of growththe giant impact stage are typically picked up after the growth ofMoon- to Mars-sized embryos have grown and are spreadthroughout the diskHere by way of simulations starting with 30 km planetesimals thatspan the entire inner region of the Solar System from 07 to 30 auwe examine the growth throughout the entire disk We find thatthe growth is strongly inside-out with Mars-sized embryos formedinside of 1 au before any embryos are formed beyond 2 auFurthermore we test various effects owing to the existence ortimescale of dispersal of the gaseous solar nebula on the stages ofgrowth and timing of instabilities

Author(s) Kevin J Walsh Harold F LevisonInstitution(s) 1 Southwest Research Institute

30206 ndash Moon formation coupled with the protolulardiskIt is thought that the Moon accreted from the protolunar disk thatwas assembled after the last giant impact on Earth Due to its hightemperature the protolunar disk may act as a thermochemicalreactor in which the material is processed before beingincorporated into the Moon Outstanding issues likedevolatilisation and istotopic evolution are tied to the diskevolution however its lifetime dynamics and thermodynamics areunknown Here we numerically explore the long term viscousevolution of the protolunar disk using a one dimensional modelwhere the different phases (vapor and condensed) are verticallystratifiedOur major innovation is that we compute at the same time theproto-moon growth along with the disk evolution and calculate thethermodynamical equilibrium of the proto-lunar seed as it growsWe will discuss the long term dynamics thermodynamics coolingtimescale and possibility for volatile depletion We will show thatdue to different effective viscosities substantial fractionation ofvolatiles and refractory material is possibleFinally we will compare different scenarios of moon impacts(standard sub-earths fast spinning Earth) and their differentadvantages for explaining todayrsquos moon material content

Author(s) Sebastien Charnoz Lisa Bugnet Chloeacute MichautInstitution(s) 1 Universiteacute Paris Diderot

30207 ndash Lunar volatile depletion due to incompleteaccretion within an impact-generated diskThe Moon likely formed from a disk produced by a giant impactwith the Earth The Moon and the bulk silicate Earth (BSE) sharemany compositional similarities (eg Ringwood 1979 Dauphas etal 2014) However compared with the BSE the Moon is moredepleted in volatile elements including moderately volatile K andNa as well as more highly volatile elements eg Zn (eg OrsquoNeill

1991 Taylor amp Wieczorek 2014) The origin of this depletion ispoorly understood Prior results suggest escape (eg Paniello et al2012) but at least hydrodynamic escape appears minimal forexpected disk conditions (Nakajima amp Stevenson 2014)In the limit of no escape and a closed system a depletion couldinstead result if disk volatiles were preferentially accreted by theEarth rather than by the Moon Taylor et al (2006) advocated thatthe lunar depletion pattern is most consistent with incompletecondensation from an initially high temperature vapor with theaccretion of condensates by the Moon ldquocut-offrdquo at a temperatureallowing incorporation of a small component of alkalis (eg K andNa) but only a tiny fraction of more volatile elements (eg Zn)Neither the mechanism that would produce the cut-off nor whatthe relevant cut-off temperature would be in an oxygen-richprotolunar disk (eg Visscher amp Fegley 2013) were knownWe identify a mechanism wherein a depletion results because diskvolatiles are preferentially accreted by the Earth rather than by theMoon The Moon may acquire the final tens to 60 of its massfrom melt originating from the inner portions of the disk (Salmonamp Canup 2012) Initially the inner disk melt is hot andvolatile-poor but as the disk cools volatiles condense We combinedynamical thermal and chemical models to show that delivery ofinner disk material to the Moon effectively ends as gravitationalinteractions cause the Moonrsquos orbit to expand away from the diskwith this cut-off occurring prior to condensation of key depletedelements The portion of the Moon derived from the inner disk isthen volatile depleted even without escape This mechanism couldproduce part or all of the observed depletion pattern dependingprimarily on the degree of mixing within the Moon

Author(s) Robin M Canup Channon Visscher JulienSalmon Bruce FegleyInstitution(s) 1 Dordt College 2 Southwest Research Inst 3Washington University

30208 ndash Formation of Phobos and Deimos in anextended circum-Martian accretion diskRecent exploration of Phobos by Mars Express has renewed theinterest in the origin of the Martian moons which remains an openissue New studies have recently focused on accretion of debris in acircum-Martian disk Craddock (Icarus 2011) has proposed ascenario of formation of such a disk (about 10 to 10 the massof Mars) from a giant collision occurred early in Mars historyRosenblatt and Charnoz (Icarus 2012) have shown that moonletscan be formed with Phobos and Deimos masses in a compact diskclose to the planet Nevertheless the orbit of these moonletsrapidly recedes back to Mars and the moonlet system vanishes inmuch less than 1 GyCitron at al (Icarus 2015) have modeled the formation of a disk ofdebris resulting from a giant collision but with a larger mass (01 of Mars mass) than in Craddock (2011) They have shown thatmost of the disk mass is concentrated close to the planet but asmall part can extend beyond the synchronous limit (6 Mars radii)We study here the accretion of debris in an extended disk focusingin the edge of this disk where surface density of material is thelowest However we take into account the gravitational influenceof the more massive bodies formed in the denser part of the diskOur results highlight the driven mechanisms of accretion in acircum-Martian disk of debris

Author(s) Pascal Rosenblatt Seacutebastien Charnoz MarikoDunseath-Terao Kevin Dunseath Antony TrinhInstitution(s) 1 Laboratoire AIM Universiteacute Paris DiderotCEACNRS 2 Royal Observatory of Belgium 3 Universiteacute deRennes-I

30209 ndash Testing Migration of the Jupiter TrojanAsteroids in the LabTodayrsquos Jupiter Trojan asteroids may have orininated in the KuiperBelt (eg Morbidelli et al Nature 2005 Nesvorny et al ApJ 2013)and migrated to capture at their present locations If this is thecase it is expected that their surfaces will contain chemical traces ofthis history No distinct spectral bands have been conclusivelyidentified in the literature however visible and near-infrared

1 1

1 1

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79

spectra of Kuiper Belt Centaur and Trojan populations each showtwo sub-populations distinguished by their spectral slopes (Brownet al ApJL 2011 Emery et al AJ 2011) The slopes are all positive(or ldquoredrdquo) steepest in the Kuiper Belt and least steep in the Trojanpopulation Here we test the hypothesis that the asteroids formedspanning a stability line for a critical substance in this case we testsulfur as H S The hypothesis is that irradiating mixed icescontaining H S will result in a refractory residue of steeper slopethan the same composition without the H S We have simulatedthis history in the Minos chamber at the Icy Worlds SimulationLaboratory at NASArsquos Jet Propulsion Laboratory Ices that will bediscussed include a 3331 mixture of H S NH CH OH H Oand a 331 mixture of NH CH OH H O After deposition at 50K the ices were irradiated with a beam of 10 keV electrons to formthe refractory crust The ices were then warmed (while continuingirradiation) to 120 K and observed for several days Reflectancespectra were collected throughout the experiment in the visible andinfrared The spectral slope increased dramatically after irradiationof the mixture containing H S while the spectral slope for themixture without any sulfur changed very little This is consistentwith sulfur being the critical component determining which of thespectral populations an object belongs to in the present inventoryof outer solar system objects Quantitative analysis is underwayThis work has been supported by the Keck Institute for SpaceStudies (KISS) The research described here was carried out at theJet Propulsion Laboratory Caltech under a contract with theNational Aeronautics and Space Administration (NASA) and at theCaltech Division of Geological and Planetary Sciences

Author(s) Michael Poston Jordana Blacksberg MikeBrown Elizabeth Carey Robert Carlson Bethany Ehlmann John Eiler Kevin Hand Robert Hodyss Ahmed Mahjoub IanWongInstitution(s) 1 California Institute of Technology 2 JetPropulsion Laboratory

304 ndash Gerard P Kuiper Prize Chemistry ofPlanetary Atmospheres Insights andProspects Yuk Yung (Caltech)30401 ndash Chemistry of Planetary AtmospheresInsights and ProspectsUsing observations from the Mariners Pioneers VikingsVoyagers Pioneer Venus Galileo Venus Express CuriosityCassini New Horizons and numerous observatories both in orbitof Earth and on the ground I will give a survey of the majorchemical processes that control the composition of planetaryatmospheres For the first time since the beginning of the spaceage we understand the chemistry of planetary atmospheresranging from the primitive atmospheres of the giant planets to thehighly evolved atmospheres of terrestrial planets and small bodiesOur understanding can be distilled into three important ideas (1)The stability of planetary atmospheres against escape of theirconstituents to space (2) the role of equilibrium chemistry indetermining the partitioning of chemical species and (3) the role ofdisequilibrium chemistry which produces drastic departures fromequilibrium chemistry To these three ideas we must also add afourth the role of biochemistry at Earths surface which makes itsatmospheric chemistry unique in the cosmochemical environmentOnly in the Earths atmosphere do strong reducing and oxidizingspecies coexist to such a degree For example nitrogen species inthe Earths atmosphere span eight oxidation states from ammoniato nitric acid Much of the Earths atmospheric chemistry consistsof reactions initiated by the degradation of biologically producedmolecules Life uses solar energy to drive chemical reactions thatwould otherwise not occur it represents a kind of photochemistrythat is special to Earth at least within the Solar System It remainsto be seen how many worlds like Earth there are beyond the SolarSystem especially as we are now exploring the exoplanets usingKepler TESS HST Spitzer soon to be launched missions such asJWST and WFIRST and ground-based telescopes Theatmospheres of the Solar System provide a benchmark for studyingexoplanets which in turn serve to test and extend our current

understanding of planetary atmospheres Ultimately we may beable to answer these profound questions Are we alone in theuniverse What makes a planet habitable How does life originateAnd what is the destiny for life on our own planet

Author(s) Yuk YungInstitution(s) 1 Caltech

305 ndash MAVEN Mission to Mars Results onUpper Atmosphere Ionosphere Solar-WindInteractions and Escape to Space BruceJakosky (University of Colorado)30501 ndash MAVEN Mission to Mars Results on UpperAtmosphere Ionosphere Solar-Wind Interactionsand Escape to SpaceThe Mars Atmosphere and Volatile Evolution (MAVEN) spacecrafthas been orbiting Mars since 21 September 2014 and collecting datain science mode since 16 November 2014 The science objectives ofthe MAVEN mission are to characterize the upper atmosphere andionospheric structure and composition the interactions of the sunand the solar wind with the planet and the processes driving loss ofgas from the atmosphere to space Our goal is to understand thechain of processes leading to escape today learn how to extrapolateback in time and determine the integrated loss of atmosphere overMartian history Measurements are being collected from all of thescience instruments in our normal mapping orbit and throughmultiple ldquodeep diprdquo campaigns Results are providing a first-timecomprehensive look at the upper-atmospheric system surroundingMars and are elucidating the key processes and history of theatmosphere Results will be integrated into a coherent view of theprocesses controlling the upper-atmosphere system and the escapeto space

Author(s) Bruce M JakoskyInstitution(s) 1 Univ of Colorado

306 ndash New Views on Inner Solar Systemsand Extreme Planets Rebekah Dawson(University of California Berkeley)30601 ndash New Views on Inner Solar Systems andExtreme PlanetsAn abundance of exoplanets have been discovered with orbitalperiods shorter than Mercuryrsquos including thousands of planets andplanet candidates found by the Kepler Mission and over a hundredby radial velocity surveys The abundance and properties of theseshort-period planets have inspired new views on planet formationand evolution in the inner regions of solar systems I will reviewresults that have caused major shifts or debates in theories ofplanet formation including where and when planets (and theirbuilding blocks) form I will highlight problems that constraintsfrom the large observed population of exoplanets are particularlywell-suited to address despite our limited knowledge of mostindividual exoplanets I will also argue for the power of the mostextreme exoplanets to serve as exceptions that prove the rulerdquo fortheories of how planets form and evolve Ongoing statistical andtheoretical studies as well as complementary exoplanetobservations from upcoming missions will help addressoutstanding questions in planet formation

Author(s) Rebekah Ilene DawsonInstitution(s) 1 University of California Berkeley

307 ndash Asteroid Spin States30701 ndash A path to asteroid bulk densitiesSimultaneous size and shape optimization fromoptical lightcurves and Keck disk-resolved data

22

2

2 3 3 23 3 2

2

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A reliable bulk density of an asteroid can be determined from theknowledge of its volume and mass This quantity provides hints onthe internal structure of asteroids and their origin We computevolume of several asteroids by scaling sizes of their 3D shapemodels to fit the disk-resolved images which are available in theKeck Observatory Archive (KOA) and the Virtual ObservatoryBinary Asteroids Database (VOBAD) The size of an asteroid isoptimized together with its shape by the All-Data AsteroidModelling inversion algorithm (ADAM Viikinkoski et al 2015AampA 576 A8) while the spin state of the original convex shapemodel from the DAMIT database is only used as an initial guess forthe modeling Updated sets of optical lightcurves are usuallyemployed Thereafter we combine obtained volume with massestimates available in the literature and derive bulk densities fortens of asteroids with a typical accuracy of 20-50On top of that we also provide a list of asteroids for which (i) thereare already mass estimates with reported uncertainties better than20 or their masses will be most likely determined in the futurefrom Gaia astrometric observations and (ii) their 3D shape modelsare currently unknown Additional optical lightcurves are necessaryin order to determine convex shape models of these asteroids Ourweb page (httpsasteroid-obsocaeufoswikibinviewMainPhotometry) contains additional information about thisobservation campaign

Author(s) Josef Hanus Matti Viikinkoski Franck Marchis Josef DurechInstitution(s) 1 Astronomical Institute Faculty of Mathematicsand Physics Charles University in Prague V Holesovickach 218000 Prague Czech Republic 2 Department of MathematicsTampere University of Technology PO Box 553 33101 TampereFinland 3 Laboratoire Lagrange UMR7293 Universite de la CotedAzur CNRS Observatoire de la Cote dAzur Blvd delObservatoire CS 34229 06304 Nice cedex 4 France 4 SETIInstitute Mountain View Mountain View CA United States

30702 ndash A Review of Asteroid Rotation Statistics withand without the Results from Wide-field SurveysSeveral recent wide-field surveys eg Waszczak et al (2015) andChang et al (2015) have added more than 10000 asteroid rotationrates to the asteroid lightcurve database (LCDB) Warner et al(2009) In previous works Harris et al (2012) Warner et al(2011) we explored the possible effects on asteroid rotationalstatistics with the large infusion of results from such surveysespecially if using ldquosparserdquo data sets eg those with fewer than 60data points from a short span of 2-4 nightsNow that such data sets exist we examine asteroid rotationstatistics with and without the results from the surveys looking attwo specific points 1) the possible biases introduced when usingsurvey data and 2) assuming that the stated results are statisticallyuseful what the larger data set now tells us about asteroid rotationratesFor point 1 there appears to be the expected substantial biasesagainst low amplitude and very short or long period lightcurveswith the period problems stemming from the observing cadenceand limited number of observations Furthermore the two latestsurveys found periods for only about 20 of all observed objectsmeaning that only the ldquoeasierrdquo results were found While the twosurveys tended to go deeper and therefore work smaller objectsthat raises yet another bias success in finding a period depends onbrightness As a result we would urge caution when interpretingspin properties versus sizeFor point 2 we first note that the vast majority of objectsobserved by the two surveys were in the broad regions of the inneror outer main-belt Significantly less than 10 NEAs were observedFor this reason it makes it difficult to compare the effects of YORPas seen by rotation rate distribution on small asteroids at differentdistances When considering main-belt objects with 10 lt D lt 40km the difference between plots with and without survey datashow essentially the same Mawellian-like distribution

Author(s) Brian D Warner Alan W Harris Robert DStephensInstitution(s) 1 Center for Solar System Studies - Palmer DivideStation 2 Center for Solar System Studies - Trojan Station 3MoreData

30703 ndash Rotational Properties of Jupiter Trojan 1173AnchisesAnchises (1173) is a large Trojan asteroid librating about JupiterrsquosL5 Lagrange point Here we examine its rotational and lightcurveproperties by way of data collected over a 35 year observingcampaign The length of the campaign means that data weregathered for more than a quarter of Anchises full orbital revolutionwhich allows for accurate determinations of pole orientation andbulk shape properties for the asteroid that can then be compared toresults of previous work (ie French 1987 Horner et al 2012) Inaddition to light curves photometric data taken during thiscampaign could potentially detect color differences betweenhemispheres as the viewing geometry changes over timeUnderstanding these details about a prominent member of theJupiter Trojans may help us better understand the history of thisfascinating and important group of asteroids

Author(s) Joseph Chatelain Todd Henry Linda French David TrillingInstitution(s) 1 Georgia State University 2 Illinois WesleyanUniversity 3 Northern Arizona University 4 RECONS Institute

30704 ndash Improved Algorithms for Radar-BasedReconstruction of Asteroid Spin States and ShapesEarth-based radar is a powerful tool for gathering informationabout bodies in the Solar System Radar observations candramatically improve the determination of the physical propertiesand orbital elements of small bodies (such as asteroids andcomets) An important development in the past two decades hasbeen the formulation and implementation of algorithms forasteroid shape reconstruction based on radar dataBecause of the nature of radar data recovery of the spin statedepends on knowledge of the shape and vice versa Even withperfect spin state information certain peculiarities of radar images(such as the two-to-one or several-to-one mapping betweensurface elements on the object and pixels within the radar image)make recovery of the physical shape challenging This is acomputationally intensive problem potentially involving hundredsto thousands of free parameters and millions of data pointsThe method by which radar-based shape and spin state modellingis currently accomplished a Sequential Parameter Fit (SPF) isrelatively slow and incapable of determining the spin state of anasteroid from radar images without substantial user interventionWe implemented a global-parameter optimizer and Square RootInformation Filter (SRIF) into the asteroid-modelling softwareshape This optimizer can find shapes more quickly than thecurrent method and can determine the asteroidrsquos spin stateWe ran our new algorithm along with the existing SPF throughseveral tests composed of both real and simulated data Thesimulated data were composed of noisy images of procedurallygenerated shapes as well as noisy images of existing shape modelsThe real data included recent observations of both 2000 ET70 and1566 IcarusThese tests indicate that SRIF is faster and more accurate thanSPF In addition SRIF can autonomously determine the spin stateof an asteroid from a variety of starting conditions a considerableadvance over the existing algorithm We will present the results ofthese comparisons along with several visualizations of the shapeand spin state fitting process

Author(s) Adam Greenberg Jean-Luc MargotInstitution(s) 1 University of California Los Angeles

30705 ndash Rotation Frequencies of Small Jovian TrojanAsteroids An Excess of Slow RotatorsSeveral lines of evidence support a common origin for and possiblehereditary link between cometary nuclei and jovian Trojanasteroids Due to their distance and low albedos few comet-sized

3 2 41

1 32

1 4 23

1 1

81

Trojans have been studied We discuss the rotation properties ofJovian Trojan asteroids less than 30 km in diameterApproximately half the 131 objects discussed here were studiedusing densely sampled lightcurves (French et al 2015a b)Stephens et al 2015) and the other half were sparse lightcurvesobtained by the Palomar Transient Factory (PTF Waszcazk et al2015)A significant fraction (~40) of the objects in the ground-basedsample rotate slowly (P gt 24h) with measured periods as long as375 h (Warner and Stephens 2011) The PTF data show a similarexcess of slow rotators Only 5 objects in the combined data sethave rotation periods of less than six hours Three of these fastrotators were contained in the data set of French et al these threehad a geometric mean rotation period of 529 hours A prolatespheroid held together by gravity rotating with this period wouldhave a critical density of 043 gmcm a density similar to that ofcomets (Lamy et al 2004)Harris et al (2012) and Warner et al (2011) have explored thepossible effects on asteroid rotational statistics with the resultsfrom wide-field surveys We will examine Trojan rotation statisticswith and without the results from the PTF

Author(s) Linda M French Robert D Stephens David JJames Daniel Coley Kyle ConnourInstitution(s) 1 Center for Solar System Studies 2 Cerro TololoInteramerican Observatory 3 Illinois Wesleyan Univ

30706 ndash Internal turmoil of small primitive bodiesrock-water-organic processing as context for Bennuand JUThe OSIRIX-REx (NASA 101955 Bennu) and Hayabusa 2 (JAXA1999 JU3) missions are set to explore small porous and primitiveasteroids (C and B type) Such bodies should contain organiccompounds and hydrated minerals Thus it is of great interest todecipher the internal structure and composition how it evolvedand how representative is the surface of the bulk interior For thiswe need to understand the physical conditions which drive thechemical evolution of water and organic-rich material through aporous medium as even main-belt asteroids of various sizes couldhave incorporated water ice upon formation Indeed the meteoriticrecord reveals such evidence in the form of hydrated mineralsmostly in the CI CM and CR carbonaceous chondrites which alsoindicate that more complex physical-chemical interactions undervarious conditions must have happened early on and set thecompositions and lithologies we observe today The precursorbodies may have also undergone early evolution and internalprocessing of mineral and organic reservoirs If conditions are metand sustained exothermic reactions (eg serpentinization andFischer-Tropsch) can contribute greatly to the overall heatingbalance and compositional variationOur thermal evolution code can deal with mixtures of water silicateminerals and organic compounds with relevant transitions andinteractions as a function of the thermodynamic variables We willutilize the robustness of the code to examine different origin andearly evolution scenarios such as parent-body evolution increasedcollision input early on orbital evolution at furthercloserperihelia varied initial composition and buried reservoirs ofvolatile compounds We will further examine the boundaryconditions in surface and near-surface layers by calculating heattransfer effects in granular material including conductionradiation and advection between particles and pores The granularmaterial can further react to vapor flows and small impactseffectively changing the diffusivity and conductivity of surfacelayersWe will present preliminary integrative models for internalevolution from formation to current state as a reactive rock-water-organic porous system

Author(s) Gal SaridInstitution(s) 1 Florida Space Institute U of Central Florida

30707 ndash Preliminary Light Curve Results of NEOsfrom the Characterization and Astrometric Follow-UpProgram at Adler Planetarium

We are nearing the halfway mark of a two-year program fornear-Earth object (NEO) astrometric follow-up andcharacterization utilizing 500 hours of observing time per year withthe Astrophysical Research Consortium (ARC) 35-meter telescopeat Apache Point Observatory (APO) Our observing is divided intotwo-hour blocks approximately every other night for astrometry(see poster by K A Nault et al) and several half-nights per monthfor spectroscopy (see poster by M Hammergren et al) and lightcurve studiesWe present preliminary results from variable photometryobservations as part of the characterization portion of the AdlerPlanetariumrsquos NEO program The frequent scheduling of half-nightobserving time allows us to capture data for small NEOs near thetime when they are closest to Earth before their apparentmagnitudes rapidly diminish beyond the range of detectability Wesearched for variability in newly discovered NEOs that had closeapproaches to Earth near the time of observation These include2014 RQ17 2014 SB145 2014 SF304 2014 WO4 2014 WY119 and2015 BC In addition we observed 2340 Hathor and 2007 EC whenthey each made a close approach to Earth to compare with lightcurves and magnitude variation constraints from previousapparitions We will construct light curves for all of the objectslisted above and determine rotational periods for those withsufficient temporal coverageThe targets were selected from candidates in the JPL NEO EarthClose Approaches table Arecibo planetary radar targets and theGoldstone asteroid radar schedule Due to the sensitivity of AGILEwe restricted our targets to those with apparent magnitudes in Vless than 19 magnitudesObservations were made using the frame transfer CCD cameraAGILE on the ARC 35-meter telescope AGILE has a field-of-viewof 22x22 and a plate scale of 0258rdquopixel with 2x2 binningThis work is based on observations obtained with the Apache PointObservatory 35-meter telescope which is owned and operated bythe Astrophysical Research Consortium We gratefullyacknowledge support from NASA NEOO award NNX14AL17G andthank the University of Chicago Department of Astronomy andAstrophysics for observing time in 2014

Author(s) Melissa J Brucker Kristie A Nault MarkHammergren Jennifer Sieben Geza Gyuk Michael RSolontoiInstitution(s) 1 Adler Planetarium 2 Illinois WesleyanUniversity 3 Lynchburg College

30708 ndash Spin-Spin Coupling in Asteroidal BinariesGravitationally bound binaries constitute a substantial fraction ofthe small body population of the solar system and characterizationof their rotational states is instrumental to understanding theirformation and dynamical evolution Unlike planets numeroussmall bodies can maintain a perpetual aspheroidal shape givingrise to a richer array of non-trivial gravitational dynamics In thiswork we explore the rotational evolution of triaxial satellites thatorbit permanently deformed central objects with specific emphasison quadrupole-quadrupole interactions Our analysis shows that inaddition to conventional spin-orbit resonances both prograde andretrograde spin-spin resonances naturally arise for closely orbitinghighly deformed bodies Application of our results to theillustrative examples of (87) Sylvia and (216) Kleopatra multi-asteroid systems implies capture probabilities slightly below ~10for leading-order spin-spin resonances Cumulatively our resultssuggest that spin-spin coupling may be consequential for highlyelongated tightly orbiting binary objects

Author(s) Konstantin Batygin Alessandro MorbidelliInstitution(s) 1 California Institute of Technology 2Observatoire de la Cocircte dAzur

30709 ndash Surprise The oft-ignored Moon mightactually be important for changing the spins ofasteroids during Earth flybysAnalysis near-Earth asteroid archival data has revealed thatasteroids with Earth MOIDs (minimum orbit intersection distancea proxy for flyby distance) smaller than 10-15 lunar distances have

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a systematically larger dispersion in spin rate than more distantflybys (Siu et al 2015 DPS) While tidal torques during closeencounters are expected to alter the spin states of asteroids (egScheeres et al 2000 Icarus) there is no intrinsic reason to expectthe observed sharp transition in spin rate distribution at 10-15lunar distances as tidal forces drop off smoothly with distanceWhile the Moon itself is too diminutive to directly alter thespin-states of asteroids we show that its presence is enough tosignificantly affect asteroid encounter trajectories Asteroidsentering the Earth-Moon system are subject to three-bodydynamics (due to the combined gravitational effects of the Earthand Moon) Depending on the flyby geometry the Moon can act asa temporary sink for the asteroids geocentric orbital energy Thisallows some fraction of asteroids to have closer approaches withthe Earth than expected when considering the Earth-Moonbarycenter alone In rare cases (~01) this process enables thecapture of temporary moons around the Earth (Granvik et al 2012Icarus) Asteroids that undergo these enhanced flybys can haveboth closer-than-expected encounter distances (resulting in moresignificant tidal perturbations) and repeated encounters with theEarth and Moon before leaving the system (resulting in theaccumulation of multiple tidal interactions) By numerically solvingthe circular restricted three-body problem we show that thisprocess naturally produces a sharp transition in the asteroidpopulation asteroids with MOIDs less than 15 lunar distances canundergo these enhanced close approaches possibly explaining thesharp transition in the dispersion of asteroid spin rates at thisdistance Future work will investigate the efficiency of this processand the relationship between the physical response of the asteroidto tidal perturbations and the statistical distribution of asteroid spinrates

Author(s) James Tuttle Keane Hosea C Siu Nicholas AMoskovitz Richard P BinzelInstitution(s) 1 Lowell Observatory 2 Massachusetts Instituteof Technology 3 University of Arizona

30710 ndash Distributions of spin axes and shapes ofasteroidsWe developed a new simplified model for the determination ofshapes and spin states of asteroids to fully exploit photometric datasparse in time (few measurements per night) which are producedby all-sky surveys and were re-calibrated into the Lowellphotometric database by Bowell et al (2014) We model asteroidsas geometrically scattering triaxial ellipsoids The model comparesobserved values of mean brightness and the dispersion ofbrightness with computed values obtained from the parameters ofthe model ndash ecliptical longitude λ and latitude β of the pole and theratio ab of axes of the ellipsoid These parameters are optimized toget the best agreement with the observation We revealed that thedistribution of λ for the main-belt asteroids is anisotropic (inagreement with findings of Bowell et al (2014)) and dependent onthe inclination of orbit (for sin i lt 004 there is an excess of λ ~ 70deg+- 180deg) We are looking for a physical or observationalmechanism that would explain this distribution From the analysisof the distribution of ab we found that larger asteroids (D gt 25km) are more often spherical (ab ~ 1) than the smaller

Author(s) Helena Cibulkova Josef Durech MikkoKaasalainen Edward Bowell Dagmara OszkiewiczInstitution(s) 1 Astronomical Institute of the CharlesUniversity 2 Astronomical Observatory Institute A MickiewiczUniversity 3 Department of Mathematics Tampere University ofTechnology 4 Lowell Observatory

30711 ndash Looking for Kilometer-Sized Super-Fast-Rotators Using PTFWe have carried out three 6-field (~40 square deg each) asteroidrotation surveys using PTF with 10 min cadence to searh forkilometer-sized super-fast rotators (SRF) in 2014 Nov 2015 Janand 2015 Feb From these surveys we found several SFRcandidates showing reasonable folded lightcurves With thesecandidates we estimate that the population of SFR is ~01 ofrubble-pile asteroid

Author(s) Chan-Kao Chang Hsing-Wen Lin Wing-HuenIpInstitution(s) 1 Institute of Astronomy National CentralUniversity Taiwan

30712 ndash Nutation damping in viscoelastic tumblingrotatorsPresently 138 asteroids show signs of being in non-principal spinstates (Warner et al 2009 updated September 2015) Such spin isoften called `tumble or `wobble The instantaneous rotation axisof a wobbling body performs nutation about the direction of the(conserved) angular-momentum vector Incited by collisions andYORP wobble is mitigated by internal dissipation due to thenutation-caused alternating stresses inside the asteroidThe knowledge of the timescale related to the damping of thenutation angle is complementary to the knowledge of thetimescales associated with collisions and YORP Previousevaluations of the nutation relaxation rate were based on aninherently inconsistent approach that may be called Q-modelFirst the elastic energy in a periodically deforming rotator wascalculated in assumption of the deformation being elasticTherefrom the energy dissipation rate was determined byintroducing an ad hoc quality factor Q This ignored the fact thatfriction (and the ensuing existence of Q) is due to deviation fromelasticityWe use the viscoelastic Maxwell model which naturally impliesdissipation (as any other viscoelastic model would) In thisapproach we compute the power and damping time for an oblateellipsoid and a prism Now the viscosity assumes the role of theproduct μQ in the empirical Q-model with μ being the rigidityContrarily to the Q-model our model naturally gives a nulldissipation for a shape tending to a sphere We also explore whenthe constant part of the stress can be ignored in the derivation ofthe damping time The neglect of prestressing turns out to belegitimate for the mean viscosity exceeding a certain thresholdvalue

Author(s) Julien Frouard Michael EfroimskyInstitution(s) 1 US Naval Observatory

30713 ndash Photometric Follow-up of Asteroid 4660Nereus and Reanalysis of its YORP EffectWe carried out new photometric observations of small near-Earthasteroid 4660 Nereus in 2013 and reanalyzed the secular change inthe asteroid rotation period due to the YORP effect The shape andpole orientation of Nereus have been derived from the radarobservations which predicts that a detectable change could occurin a few years (Brozovic et al 2009) Since the YORP-inducedlinear change of rotation period leads to a phase lag that isquadratic in time we examined it by comparing 22 lightcurvesobserved in 1997-2013 with the modeled ones The new dataset oflightcurves enabled us to further constrain the solutions of theasteroid rotational state and we found that it would be difficult toreproduce the observed lightcruves with a constant-period model

Author(s) Kohei Kitazato Shinsuke Abe MasateruIshiguro Yukihiro Ishibashi Yuhei Takagi Masanao AbeInstitution(s) 1 Japan Aerospace Exploration Agency 2 NihonUniversity 3 Seoul National University 4 University of Aizu 5University of Hyogo

308 ndash Asteroid Observational Surveys30801 ndash The Near-Earth Object Camera ANext-Generation Minor Planet SurveyThe Near-Earth Object Camera (NEOCam) is a next-generationasteroid and comet survey designed to discover characterize andtrack large numbers of minor planets using a 50 cm infraredtelescope located at the Sun-Earth L1 Lagrange point Proposed toNASAs Discovery program NEOCam is designed to carry out acomprehensive inventory of the small bodies in the inner regionsof our solar system It address three themes 1) quantify thepotential hazard that near-Earth objects may pose to Earth 2)

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study the origins and evolution of our solar system as revealed byits small body populations and 3) identify the best destinations forfuture robotic and human exploration With a dual channelinfrared imager that observes at 4-5 and 6-10 micron bandssimultaneously through the use of a beamsplitter NEOCamenables measurements of asteroid diameters and thermal inertiaNEOCam complements existing and planned visible light surveysin terms of orbital element phase space and wavelengths sincealbedos can be determined for objects with both visible andinfrared flux measurements NEOCam was awarded technologydevelopment funding in 2011 to mature the necessary megapixelinfrared detectors

Author(s) Amy K Mainzer Edward L Wright JamesBauer Tommy Grav Roc M Cutri Joseph Masiero Carolyn RNugentInstitution(s) 1 IPACCaltech 2 JPL 3 PSI 4 UCLA

30802 ndash Asteroid Detection Results Using the SpaceSurveillance TelescopeFrom 1998-2013 MIT Lincoln Laboratory operated a highlysuccessful near-Earth asteroid search program using two 1-moptical telescopes located at the MIT Lincoln LaboratoryExperimental Test Site (ETS) in Socorro NM In 2014 the LincolnNear-Earth Asteroid Research (LINEAR) program successfullytransitioned operations from the two 1-m telescopes to the 35-mSpace Surveillance Telescope (SST) located at Atom Site on WhiteSands Missile Range NM This paper provides a summary offirst-year performance and results for the LINEAR program withSST and provides an update on recent improvements to themoving-object pipeline architecture that increase utility of SST datafor NEO discovery and improve sensitivity to fast-moving objectsRuprecht et al (2014) made predictions for SST NEO searchproductivity as a function of population model This paper assessesthe NEO search performance of SST in the first 15 years ofoperation and compares results to model predictionsThis work is sponsored by the Defense Advanced Research ProjectsAgency and the National Aeronautics and Space Administrationunder Air Force Contract FA8721-05-C-0002 The viewsopinions andor findings contained in this articlepresentation arethose of the authors presenters and should not be interpreted asrepresenting the official views or policies of the Department ofDefense or the US Government Distribution Statement AApproved for public release distribution unlimited

Author(s) Jessica D Ruprecht Gregory Ushomirsky Deborah F Woods Herbert E M Viggh Jacob Varey Mark ECornell Grant StokesInstitution(s) 1 MIT Lincoln Laboratory 2 MITLL ETS FieldSite

30803 ndash Absolute magnitudes and slope parametersfor 250000 asteroids observed by Pan-STARRS1Absolute magnitude (H) of an asteroid is used for thedetermination of its diameter and apparent brightness Theobserved brightness changes as a function of asteroids geometrywith respect to the Sun and Earth and surface properties of theasteroid which is described by a phase function depending on theslope parameter (G) H and G parameters are derived from mostlyoptical observations of asteroids Nowadays databases of asteroidobservations contain millions of entries coming from multipletelescopic surveys employing different photometric calibrationsand standards They usually lack information on photometricerrors and photometric precision is truncated above thephotometric accuracy of current major surveys We derived H andG of almost 250000 asteroids observed by a single survey ndashPan-STARRS1 - during its first 15 months of operation 1250000detections in our sample were filtered by morphological parametersand photometric quality and achieved photometric errors less than004 mag Our method was based on Monte Carlo technique and asparse Bayesian marginalization over taxonomic classification lightcurve amplitude and period and both Bowells (1989) andMuinonens (2010) phase functions Resulting H and G valueswere derived with statistical and systematic uncertainties and

errors The method was tested by comparison with accurate resultsfor about 500 asteroids provided by Pravec et al (2012) and resultsagree with Oszkiewicz et al (2012) work Our results confirm thatthe bias discovered by Juric et al (2002) and confirmed by Parkeret al (2008) and Pravec et al (2012) is still present in Minor PlanetCenter photometry The trend of G depending on semi-major axiswas confirmed as well Derived table of H and G and other relevantparameters is publicly available at httpwwwifahawaiieduNEO This work was supported by NASA grant NoNNX12AR65G

Author(s) Peter Veres Robert Jedicke Alan Fitzsimmons Larry Denneau Mikael Granvik Bryce Bolin Serge Chastel Richard WainscoatInstitution(s) 1 Institute for Astronomy University of Hawaii2 Jet Propulsion Laboratory California Institute of Technology 3Queenrsquos University 4 University of Helsinki 5 UNS-CNRS-Observatoire de la Cote dlsquoAzur

30804 ndash Dormant Comets in the Near-Earth AsteroidPopulationThe population of near-Earth objects comprises active comets andasteroids covering a wide range of dynamical parameters andphysical properties Dormant (or extinct) comets masquerading asasteroids have long been suspected of supplementing thenear-Earth asteroid (NEA) population We present a search forasteroidal objects of cometary origin based on dynamical andphysical considerations Our study is based on albedos derivedwithin the ExploreNEOs program and is extended by adding datafrom NEOWISE and the Akari asteroid catalog We use a statisticalapproach to identify asteroids on orbits that resemble those ofshort-period near-Earth comets using the Tisserand parameterwith respect to Jupiter the aphelion distance and the minimumorbital intersection distance with respect to Jupiter We identify atotal of 23 near-Earth asteroids from our sample that are likely tobe dormant short-period near-Earth comets and based on ade-biasing procedure applied to the cryogenic NEOWISE surveyestimate both magnitude-limited and size-limited fractions of theNEA population that are dormant short-period comets We findthat 03-33 of the NEA population with H lt= 21 and 9(+2-5)of the population with diameters d gt= 1 km are dormant short-period near-Earth comets We also present an observation programthat utilizes the 18m Vatican Advanced Technology Telescope(VATT) on Mt Graham AZ to identify dormant comet candidatesand search for activity in these objects Our targets are NEAs oncomet-like orbits based on the dynamical criteria derived in theabove study that are accessible with the VATT (V lt= 22) Weidentify dormant comets based on their optical spectral sloperepresented by V-R color measurements as albedo measurementsfor most of these objects are not available For each target wemeasure and monitor its V magnitude in order to reveal activityoutbreaks We also search for extended emission around ourtargets using deep imaging and a point-spread-function subtractiontechnique that allows us to obtain an upper limit on the dustproduction rate in each target We present preliminary results fromthis program This work is supported in part by funding from theSpitzer Science Center

Author(s) Michael Mommert Alan W Harris MichaelMueller Joseph L Hora David E Trilling Matthew Knight William F Bottke Cristina Thomas Marco Delbo Josh PEmery Giovanni Fazio Howard A SmithInstitution(s) 1 Deutsches Zentrum fuer Luft- und Raumfahrt2 Harvard-Smithsonian CfA 3 Lowell Observatory 4 NorthernArizona University 5 Observatoire de la Cote dAzur 6 PSI 7SRON 8 SWRI 9 University of Tennessee

30805 ndash The Asteroid 2015 KA122The Asteroid ldquo2015 KA122rdquo was discovered on May 252015 by theCatalina Sky Survey This object is not well known Its absolutemagnitude of 232 indicates a diameter of about 70 meters Theasteroid was at aproximately 33 lunar distances from the Earth onJune 62015 It has an orbital period of 211 years From ourObservatory located in Pasto-Colombia we captured several

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pictures videos and astrometry data during three days Our datawas published by the Minor Planet Center (MPC) and also appearsat the web page of NEODyS Our observatoryrsquos code at the MPC isldquoH78rdquo Pictures of the asteroid were captured with the followingequipment 14rdquo LX200 GPS MEADE (f10 Schmidt-CassegrainTelescope) and STL-1001 SBIG camera Astrometry was carriedout and we calculated the orbital elements We obtained thefollowing orbital parameters eccentricity = 04089630 +-000189 semi-major axis = 164254884 +- 000505 AU orbitalinclination = 1268490 +- 0039 deg longitude of the ascendingnode = 7314715 +- 00013 deg argument of perihelion =21482393 +- 0007 deg orbital period = 211 years (76890 days)mean motion = 046819485 +- 000216 degd perihelion distance= 097080706 +- 0000119 AU aphelion distance = 231429061+- 00103 AU The parameters were calculated based on 81observations (2015 June 3-5) with mean residual = 0343arcseconds Our videos appear in the following linkshttpspaceweathergallerycomindiv_uploadphpupload_id=113197httpspaceweathergallerycomindiv_uploadphpupload_id=113238ampPHPSESSID=f2lkigjogsfgcmi1rscc9jil36httpspaceweathergallerycomindiv_uploadphpupload_id=113257

Author(s) Alberto Quijano Vodniza Mario Rojas PereiraInstitution(s) 1 University of Narino Observatory

30806 ndash Target-of-Opportunity Characterization of100-Meter Class Near-Earth AsteroidsIt is generally believed that minor planet rotation periods smallerthan ~2 hours are indicative of non-negligible tensile strength forthese objects [1] This would put limits on the degree of fracture oreven suggest a monolithic structure for fast rotating asteroidsCombining rotations rates with spectral information for 100-meterclass Near-Earth asteroids (NEAs) can provide an even betterunderstanding of the physical properties and collisional history ofthe smaller members of the asteroid population which are alsothose that will impact the Earth with the most frequencyRobust characterization of 100-meter class asteroids is usuallylimited to when these objects make close approaches to the EarthThe observing window for such studies is usually weeks days orfor the smallest members of this population just a single day ortwo bracketing their closest approach to Earth For many the onlyoptimal occasions for investigation for the foreseeable future occurimmediately after discovery Therefore these are truly targets-of-opportunityAs part of an effort to obtain astrometric data on newly discoverednear-Earth asteroids using the Magdalena Ridge Observatoryrsquos(MRO) 24-meter telescope a program has been implemented toobtain rotation rate and spectral information on 100-meter classand smaller NEAs [2] Prioritized are recently discovered objectsthat have limited observing prospects Results thus far have shownthat although slow rotators do exists in this size regime about 70of our targets with absolute magnitude Hgt22 have rotation periodsless than 2 hours In addition approximately 20 of our targetshave indicated tumbling behavior with primary periods rangingfrom hours to minutes Therefore any origin model must beconsistent with the observed rotation rate distribution allow forthe existence of a significant fraction of tumblers and be consistentwith the evolving spectral class distribution For this effort wequantify the observing window that exists for various objects in thissize regime using the MRO 24-meter telescope We then present asample of recent lightcurve and spectral results from this program[1] Pravec et al Asteroids III 2002[2] Ryan and Ryan DPS 2014

Author(s) William Ryan Eileen V RyanInstitution(s) 1 NM TechMRO

30807 ndash Radar Observations of Near-Earth Asteroid(52760) 1998 ML14 Constraints from the 1998 and2013 ApparitionsOstro et al (Meteoritics amp Planetary Science 36 1225-1236 2001)

produced a shape model of the approximately 1-km diameternear-Earth asteroid (52760) 1998 ML14 using radar images takenwith the Arecibo and Goldstone planetary radar systems in 1998However the spin state (pole orientation and rotation period) wasnot well determined in their modelling The published shape modelwas produced using a 1483 h sidereal rotation period consistentwith the synodic period of 1498 plusmn 006 h found by opticalobservations in 1998 (Hicks amp Weissman IAU Circular 6987 11998) Optical observations in 2013 found a faster period of 1428 plusmn001 h (Warner The Minor Planet Bulletin 41 2 113-124 2014)Further radar observations at Arecibo in 2013 are inconsistent withthe 1483 h sidereal period Use of Arecibo radar images from bothapparitions with resolution as fine as 15 m per pixel are best fit bya sidereal period within 1 of 1428 h and constrain the poleorientation to within approximately ten degrees An updated shapemodel will be presented using this new information Theseimproved constraints illustrate the power of multiple apparitionsfor better determining the true shapes and spin states ofnear-Earth asteroids

Author(s) Benjamin N L Sharkey Patrick A Taylor Michael C Nolan Ellen S HowellInstitution(s) 1 Arecibo Observatory 2 LPLU Arizona 3University of Minnesota - Twin Cities

30808 ndash Arecibo and Goldstone Radar Observationsof the First-Recognized Binary Near-Earth Asteroid(385186) 1994 AW1Near-Earth asteroid (385186) 1994 AW1 was discovered at PalomarObservatory on 11 January 1994 Subsequent observations of thisAmor family Sa-class asteroid also identified it as the firstcandidate binary NEA as indicated by multiple periodicities andpossible mutual eclipsingocculting events in the objectrsquoslightcurve On 15 July 2015 this asteroid made its closest approachto Earth since its discovery coming within 0065 AU (25 lunardistances) and prompting an extended observation campaignusing both the JPL-Goldstone and Arecibo Observatory planetaryradars Goldstone observations covered the 14-19 July period ofclosest approach (0066-0070 AU) while the object remainedbelow Areciborsquos observing horizon with Arecibo picking up theobservations between 20-30 July as the object moved from 0075to 0126 AU distance At Goldstone we were able to observe thisobject with range resolutions of 150 m using a Goldstone (DSS-14)to Green Bank Telescope (GBT) bistatic configuration while atArecibo we conducted monostatic observations of 1994 AW1 usingthe 2380 MHz (126 cm) radar at resolutions of 30 m and 75 mAs a result and twenty years after its discovery these observationshave confirmed the binary nature of 1994 AW1 showing theprimary body to be about 600 m in diameter the secondary body tobe about half the diameter of the primary with the two orbiting acommon center of mass at a distance of about 12 km apart Delay-Doppler image comparisons of the primary over the course of sixnights (at 30 m resolution) confirm a lightcurve-derived rotationperiod of 2518 +- 0002 hr as gt90 longitude coverage wasachieved revealing a slightly elongated irregular surfacemorphology Delay-Doppler images of the secondary reveal anelongated irregular body which appears to be tidally locked withits long axis pointed towards the primary as it orbits with a period ofabout 22 hr (also consistent with the lightcurve analysis) Thesevery early results point to a total system mass of (16 +- 05) x10^11 kg and a crude mean system density estimate of 1400 +-500 kgm^3 Additional analysis and shape-modeling will bepresented

Author(s) James E Richardson Patrick A Taylor EdgardG Rivera-Valentin Linda A Rodriguez-Ford Lance AMBenner Shantanu P Naidu Jon D Giorgini Michael WBusch Frank d Ghigo Adam Kobelski Brian D Warner Alessondra Springmann Sean E Marshall Jordan K Steckloff Benjamin SharkeyInstitution(s) 1 Arecibo Observatory (USRA) 2 Center forSolar System Studies 3 Cornell University 4 Jet PropulsionLaboratory 5 National Radio Astronomy Observatory 6 PurdueUniversity 7 SETI Institute 8 University of Arizona 9University of Minnesota Twin Cities

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30809 ndash LSSTrsquos Projected Near-Earth AsteroidDiscovery PerformanceThe Large Synoptic Survey Telescope (LSST) is an ambitiousproject that has the potential to make major advances inNear-Earth Asteroid search efforts With construction alreadyunderway and major optical elements complete first light is set for2020 followed by two years of commissioning Once regular surveyoperations begin in 2022 LSST will systematically survey theobservable sky over a ten-year period from its site on CerroPachon Chile With an 84 m aperture (65 m effective) 96 squaredegree field of view and a 32-Gigapixel camera LSST representsthe most capable asteroid survey instrument ever builtLSST will be able cover over 6000 square degrees of sky per clearnight with single visit exposures of 30 s reaching a faint limit of245 mag in the r band However the cadence of survey operationsis a critical factor for the near-Earth asteroid search performanceand there are multiple science drivers with different cadenceobjectives that are competing to shape the final survey strategy Weexamine the NEA search performance of various LSST searchstrategies paying particular attention to the challenges of linkinglarge numbers asteroid detections in the presence of noiseOur approach is to derive lists of synthetic detections for a giveninstantiation of the LSST survey based on an assumed model forthe populations of solar system objects from the main asteroid beltinwards to the near-Earth population These detection lists arecombined with false detection lists that model both random noiseand non-random artifacts resulting from image differencingalgorithms These large detection lists are fed to the Moving ObjectProcessing System (MOPS) which attempts to link the syntheticdetections correctly without becoming confused or overwhelmedby the false detectionsThe LSST baseline survey cadence relies primarily on single nightpairs of detections with roughly 30-60 min separating elements ofthe pair The strategy of using pairs is an aggressive and potentiallyfragile approach but theoretically represents the most productiveNEA search with the minimum impact on other LSST sciencedrivers

Author(s) Steven R Chesley Peter VerešInstitution(s) 1 JPL

30810 ndash The Mission Accessible Near-Earth ObjectSurvey (MANOS) mdash First ResultsThe Mission Accessible Near-Earth Object Survey (MANOS) beganin August 2013 as a multi-year physical characterization surveythat was awarded survey status by NOAO and has since expandedoperations to include facilities at Lowell Observatory and theUniversity of Hawaii MANOS will target several hundred mission-accessible NEOs across visible and near-infrared wavelengthsproviding a comprehensive catalog of physical properties(astrometry light curves spectra) Particular focus is paid tosub-km NEOs where little data currently exists These small bodiesare essential to understanding the link between meteorites andasteroids pose the most immediate impact hazard to the Earth andare highly relevant to a variety of planetary mission scenariosObserving these targets is enabled through a combination ofclassical queue and target-of-opportunity observations carried outat 1- to 8-meter class facilities in both the northern and southernhemispheres The MANOS observing strategy enables thecharacterization of roughly 10 of newly discovered NEOs beforethey fade beyond observational limitsTo date MANOS has obtained data on over 200 sub-km NEOs andwill ultimately provide major advances in our understanding of theNEO population as a whole and for specific objects of interest Herewe present first results from the survey including (1) the de-biasedtaxonomic distribution of spectral types for NEOs smaller than~100 meters (2) the distribution of rotational properties for smallobjects with high Earth-encounter probabilities (3) progress indeveloping a new set of online tools at asteroidlowelledu that willhelp to facilitate observational planning for the small body observercommunity and (4) physical properties derived from rotationallight curvesMANOS is supported through telescope allocations from NOAOLowell Observatory and the University of Hawaii We acknowledge

funding support from NASA NEOO grant number NNX14AN82Gand an NSF Astronomy and Astrophysics Postdoctoral Fellowshipto N Moskovitz

Author(s) Nicholas Moskovitz Louis Avner RichardBinzel Brian Burt Eric Christensen Francesca DeMeo MaryHinkle Michael Mommert Michael Person David Polishook Robert Schottland Hosea Siu Audrey Thirouin CristinaThomas David Trilling Lawrence Wasserman Mark WillmanInstitution(s) 1 CSSUA 2 Lowell Observatory 3 MIT 4Northern Arizona University 5 PSI 6 University of Hawaii 7Weizmann Institute of Science

30811 ndash Albedo Size and Taxonomy of the Small BodyPopulations Outside the Main BeltUsing the data from the WISENEOWISE mission we have derivedalbedo and size distributions of ~1200 Cybeles ~1000 Hildas~1700 Jovian Trojans and a dozen irregular satellites of Jupiter andSaturn These data increases by an order of magnitude ourknowledge of the makeup of the small body populations betweenthe Main Belt and Saturn We find that all these populations aredominated by low albedo objects with only the Cybeles (with lessthan 10) having any significant fraction of possible interloperobjects with albedo higher than 15 Using the near-infraredalbedos (in the 34 and 46μm bands denoted W1 and W2respectively) we were able to derive the taxonomic classifications ofthe largest objects in each population showing that they aredominated by surfaces that are similar to C- P- and D-typeasteroids The dominance of these dark primitive surfaces indicatetwo possible formation scenarios These small body populationsmay have been formed in situ beyond the snow line potentiallyserving as bodies that can provide significant insight into thecomposition of the early Solar Nebula in the region of the currentGiant Planets Alternatively they may be captured bodies that wereperturbed from the region outside the Giant Planets as the planetsmigrated during the early stages of Solar System formation Thisallows for insight into the composition of the Trans-Neptunianpopulation by study of populations that are significantly closerbrighter and more accessible The low percentages of potentiallyhigher albedo stony objects common in the Main Asteroid Beltindicates that only a few of these objects have embeddedthemselves into these populations potentially imposing significantconstraints on the migration of Jupiter inside its current orbit

Author(s) Tommy Grav Amy Mainzer James Bauer Joseph R Masiero Roc Cutri Carrie Nugent Sarah Sonnett Emily A KramerInstitution(s) 1 Infrared Processing and Analysis Center -California Institute of Technology 2 Jet Propulsion Laboratory 3Planetary Science Institute

30812 ndash Results from the LCOGT Near-Earth ObjectFollow-up NetworkLas Cumbres Observatory Global Telescope Network (LCOGT) hasdeployed a homogeneous telescope network of nine 1-meter andtwo 2-meter telescopes to five locations in the northern andsouthern hemispheres with plans to extend to twelve 1-metertelescopes at 6 locations The versitility and design of this networkallows for rapid response to target of opportunity events as well asthe long-term monitoring of slowly changing astronomicalphenomena The networks global coverage and the apertures oftelescopes available make LCOGT ideal for follow-up andcharacterization of Solar System objects (eg asteroids Kuiper BeltObjects comets Near-Earth Objects (NEOs)) and ultimately forthe discovery of new objectsLCOGT has completed the first phase of the deployment with theinstallation and commissioning of the nine 1-meter telescopes atMcDonald Observatory (Texas) Cerro Tololo (Chile) SAAO (SouthAfrica) and Siding Spring Observatory (Australia) This iscomplimented by the two 2-meter telescopes at Haleakala (Hawaii)and Siding Spring Observatory The telescope network has beenfully operational since May 2014 and observations are beingexecuted remotely and robotically Future expansion to sites in theCanary Islands and Tibet are planned for 2016

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The LCOGT near-Earth object group is using the network toconfirm newly detected NEO candidates produced by the major skysurveys such as Catalina Sky Survey (CSS) PanSTARRS (PS1) andNEOWISE with several hundred targets being followed per yearFollow-up astrometry and photometry of radar-targeted objectsand those on the Near-Earth Object Human Space FlightAccessible Targets Study (NHATS) or Asteroid Retrieval Mission(ARM) lists are improving orbits producing light curves androtation periods and better characterizing these NEOs Recentresults include the first period determinations for several of theGoldstone-targeted NEOs In addition we are in the process ofbuilding a NEO portal that will allow professionals amateurs andCitizen Scientists to plan schedule and analyze NEO imaging andspectroscopy observations and data using the LCOGT Network andto act as a coordination hub for the NEO follow-up efforts

Author(s) Sarah Greenstreet Tim Lister Edward Gomez Eric Christensen Steve LarsonInstitution(s) 1 Catalina Sky Survey 2 Las CumbresObservatory Global Telescope Network

30813 ndash Searching for a Differentiated AsteroidFamily A Spectral Survey of the Massalia Merxia andAgnia FamiliesAsteroid families were formed by catastrophic collisions or largecratering events that caused fragmentation of the parent body andejection of asteroidal fragments with velocities sufficient to preventre-accretion Due to these formation processes asteroid familiesshould provide us with the opportunity to probe the interiors of theformer parent bodies Differentiation of a large initially chondriticparent body is expected to result in an onion shell object with aniron-nickel core a thick olivine-dominated mantle and a thinplagioclasepyroxene crust However most asteroid families tendto show similar spectra (and therefore composition) among themembers Spectroscopic studies have observed a paucity ofmetal-like materials and olivine-dominated assemblages within theMain Belt asteroid familiesThe deficit of olivine-rich mantle material in the meteorite recordand in asteroid observations is known as the Missing Mantleproblem For years the best explanation has been the battered tobits hypothesis that all differentiated parent bodies (aside fromVesta) were disrupted very early in the Solar System and theresulting olivine-rich material was collisionally broken down overtime until the object diameters fell below our observational limitsIn a competing hypothesis Elkins-Tanton et al (2013) havesuggested that previous work has overestimated the amount ofolivine produced by the differentiation of a chondritic parent bodyWe are conducting a visible and near-infrared wavelength spectralsurvey of asteroids in the Massalia Merxia and Agnia S-type MainBelt asteroid families These families were carefully chosen for theproposed spectroscopic survey because they have compositionsmost closely associated with a history of thermal metamorphismand because they represent a range of collisional formationscenarios In addition the relatively young ages (under 400 Myr)of these families permit testing of the ldquobattering to bits timescaleWe will present initial results from our ongoing spectral survey ofthese three Main Belt families and discuss evidence fordifferentiation among the family membersWe acknowledge funding support from the NASA PlanetaryAstronomy program

Author(s) Cristina A Thomas Lucy Lim NicholasMoskovitz David TrillingInstitution(s) 1 Lowell Observatory 2 NASA GSFC 3 NASAGSFCUSRA 4 Northern Arizona University

30814 ndash Public Archiving and Curation of SpacewatchDataImage data from Spacewatchs astrometry of asteroids date back to1985 At this meeting we introduce data from the most voluminousmode of operation of Spacewatch to the web for public access Thesurvey with the Spacewatch 09-meter telescope has goodastrometric and photometric accuracy and revisits the same cohortsof main belt asteroids at 4-day intervals by migrating the telescope

pointings appropriately This pattern has made possiblemulti-night prediscovery detections (precoveries) of Near EarthObjects (NEOs) when they were distant slowly moving andtherefore originally unnoticed and is a similarly unique asset toother researches in the temporal domain Limiting V magnitude is20-215 and sky coverage is 1400 square degrees per lunationthree times per position This survey has been in operationuniformly with the same equipment and procedure from 2003 tothe present (2015) producing some 17 TB of imaging dataProcessing includes documentation of instrumental parametersbias subtraction flat-fielding defringing positional registrationastrometric mapping and indexing relevant image parameters to asearchable database Tools for finding images that contain movingobjects will be demonstrated at the meeting Examples ofapplications of these data are prediscovery observations of NEOsand comets to improve knowledge of the objects orbits Asteroidswhose orbits and albedos suggest that they might be dormantcomets can also be checked for cometary features Beyond the solarsystem the cadence of the Spacewatch mosaic data will providephotometric sampling of variable stars and galaxies on time scalesfrom tens of minutes to 12 years a range rarely available fromdatabases of this typeSupport of Spacewatch wasis from a JPL subcontract (2010-2011)NASANEOO grants the Lunar and Planetary Laboratory StewardObservatory Kitt Peak National Observatory the BrinsonFoundation of Chicago IL the estates of R S Vail and R LWaland and other private donors We are also indebted to theMPC and JPL for their web services

Author(s) Jeffrey A Larsen Robert S McMillan TerrenceH Bressi Ronald A Mastaler James V Scotti Andrew FTubbioloInstitution(s) 1 Lunar and Planetary Laboratory University ofArizona 2 US Naval Academy

30815 ndash Astrometric Results of NEOs from theCharacterization and Astrometric Follow-up Programat Adler PlanetariumWe present astrometric results of near-Earth objects (NEOs)targeted in fourth quarter 2014 and in 2015 This is part of AdlerPlanetariumrsquos NEO characterization and astrometric follow-upprogram which uses the Astrophysical Research Consortium(ARC) 35-m telescope at Apache Point Observatory (APO) Theprogram utilizes a 17 share of telescope time amounting to a totalof 500 hours per year This time is divided up into two hourobserving runs approximately every other night for astrometry andfrequent half-night runs approximately several times a month forspectroscopy (see poster by M Hammergren et al) and light curvestudies (see poster by M J Brucker et al)Observations were made using Seaver Prototype Imaging Camera(SPIcam) a visible-wavelength direct imaging CCD camera with2048 x 2048 pixels and a field of view of 478rsquo x 478rsquo Observationswere made using 2 x 2 binningSpecial emphasis has been made to focus on the smallest NEOsparticularly around 140m in diameter Targets were selected basedon absolute magnitude (prioritizing for those with H gt 25 mag toselect small objects) and a 3σ uncertainty less than 400rdquo to ensurethat the target is in the FOV Targets were drawn from the MinorPlanet Center (MPC) NEA Observing Planning Aid the JPL WhatrsquosObservable tool and the Spaceguard priority list and faint NEO listAs of August 2015 we have detected 670 NEOs for astrometricfollow-up on point with our goal of providing astrometry on athousand NEOs per year Astrometric calculations were done usingthe interactive software tool Astrometrica which is used for datareduction focusing on the minor bodies of the solar system Theprogram includes automatic reference star identification fromnew-generation star catalogs access to the complete MPC databaseof orbital elements and automatic moving object detection andidentificationThis work is based on observations done using the 35-m telescopeat Apache Point Observatory owned and operated by theAstrophysical Research Consortium We acknowledge the supportfrom the NASA NEOO award NNX14AL17G and thank theUniversity of Chicago Astronomy and Astrophysics Department for

2 2 21 1

3 21 4

2 11 1 11

87

observing time in 2014

Author(s) Kristie A Nault Melissa J Brucker MarkHammergren Geza Gyuk Mike R SolontoiInstitution(s) 1 Adler Planetarium 2 Lynchburg College

30816 ndash The Las Cumbres Observatory (LCOGT)Network for NEO and Solar System ScienceLas Cumbres Observatory Global Telescope Network (LCOGT) hasdeployed a homogeneous telescope network of nine 1-metertelescopes to four locations in the northern and southernhemispheres with a planned network size of twelve 1-metertelescopes at 6 locations This 1-meter network is in addition to thetwo 2-meter Faulkes Telescopes that have been operating since2005 This network is very versatile and is designed to respondrapidly to target of opportunity events and also to perform longterm monitoring of slowly changing astronomical phenomena Theglobal coverage of the network and the apertures of telescopeavailable make LCOGT ideal for follow-up and characterization ofSolar System objects eg Near-Earth Objects (NEOs) cometsasteroids and Kuiper Belt Objects and also for the discovery of newobjectsLCOGT has completed the first phase of the deployment with theinstallation and commissioning of the nine 1-meter telescopes atMcDonald Observatory (Texas) Cerro Tololo (Chile) SAAO (SouthAfrica) and Siding Spring Observatory (Australia) The telescopenetwork has been fully operational since 2014 May andobservations are being executed remotely and robotically Futureexpansion to sites in the Canary Islands and Tibet are planned for2016-2017I will describe the Solar System science research that is beingcarried out using the LCOGT Network with highlights from theLCOGT NEO Follow-up Network long-term monitoring of theRosetta spacecraft target comet 67P and comet C2013 A1 (SidingSpring) and work on Kuiper Belt Object occultation targetsincluding Pluto

Author(s) Tim Lister Sarah Greenstreet Edward Gomez Eric Christensen Stephen LarsonInstitution(s) 1 Las Cumbres Observatory 2 University ofArizona

30817 ndash Searching for dormant comets in the NEOregion using data from the Canadian Meteor OrbitRadarDormant comets (DCs) are objects that appear asteroidal but havecometary origins Earth-approaching DCs may produce dust duringtheir final active stages which potentially are detectable as weakmeteor showers at the Earth However identifying DCs is difficultas they are observationally indistinguishable from asteroids Pastasteroid-stream searches have produced some possible linkagesbetween asteroids and meteor showers the most notable being theGeminids and 3200 (Phaethon) and the Quadrantids and (196256)2003 EH1 However a comprehensive survey to look for allpossible weak streams from recent DC activity including dynamicalformation and evolution of early dust trails has yet to beperformed Here we report on the progress of a DC meteoroidstream survey whereby we have identified all DC candidates whoseorbits are such that recent (last several hundred years) dust releasewould be currently detectable at the Earth We have simulated theevolution of dust trails for all candidate DC-stream objects andgenerate predictions for the characteristics of the associated DCshower at Earth We then perform a cued survey for such streamsamong the 15 mega meteoroid orbits measured by CMOR since2002 using a wavelet-based search algorithm with probe sizestuned to the expected shower characteristics The search is focusedon ~300 Earth-approaching asteroids that have dynamicalcharacteristics of comets (or asteroids in cometary orbits ACOs)For some cases we will also discuss the connection between themeteor data and astrophysical observations of the parent bodyitself

Author(s) Quan-Zhi Ye Peter BrownInstitution(s) 1 The University of Western Ontario

30818 ndash Meteor shower forecast improvements froma survey of all-sky network observationsMeteoroid impacts are capable of damaging spacecraft andpotentially ending missions In order to help spacecraft programsmitigate these risks NASArsquos Meteoroid Environment Office (MEO)monitors and predicts meteoroid activity Temporal variations innear-Earth space are described by the MEOrsquos annual meteorshower forecast which is based on both past shower activity andmodel predictionsThe MEO and the University of Western Ontario operate sisternetworks of all-sky meteor cameras These networks have been inoperation for more than 7 years and have computed more than20000 meteor orbits Using these data we conduct a survey ofmeteor shower activity in the ldquofireballrdquo size regime using DBSCANFor each shower detected in our survey we compute the date ofpeak activity and characterize the growth and decay of the showerrsquosactivity before and after the peak These parameters are thenincorporated into the annual forecast for an improved treatment ofannual activity

Author(s) Althea V Moorhead Glenn Sugar Peter GBrown William J CookeInstitution(s) 1 NASA 2 Stanford University 3 University ofWestern Ontario

30819 ndash Status of The Catalina Sky SurveyThe Catalina Sky Survey (CSS) continues to be a key contributor toNASArsquos Near-Earth Object (NEO) survey effort accounting for 42of all new discoveries in the last calendar year (618 of 1478)Recent upgrades and improvements include the routine queue-scheduled remote operation of a 10-m telescope principallydedicated to the follow-up of newly discovered NEOsenhancement of the moving object detection software resulting in a10-15 increase in efficiency reduction in acquisition overheadsresulting in ~10 higher data throughput and changes to the datareduction pipeline which have yielded overall better data quality(flat-fielding astrometry and photometry) Significantinstrumentation upgrades to the 15-m telescope (MPC code G96)and 07-m Schmidt telescope (MPC code 703) are underwaydespite significant delays in procuring science-grade 10k x 10kdetectors The G96 camera has been fully assembled in the lab andon-sky commissioning is imminent When complete these newcameras will increase the fields-of-view of the 15-m and 07-m by40x (to 50 sq deg) and 24x (to 194 sq deg) dramaticallyexpanding the nightly coverage for both telescopesThe Catalina Sky Survey is funded by NASArsquos Near-Earth ObjectObservation program (NNX15AF79G)

Author(s) Eric J Christensen David Carson Fuls Alex RGibbs Albert D Grauer Rik E Hill Jess A Johnson Richard AKowalski Stephen M Larson Rose G Matheny Frank C ShellyInstitution(s) 1 The University of Arizona

30820 ndash A systematic search for undiscoveredcompanions to near-Earth asteroids in radar imagesRadar observations have been paramount to the characterization ofsmall (lt20 km) Near-Earth Objects (NEOs) specifically withregards to asteroid trajectories shapes spins and multi-component systems Binary systems make up a sizable fraction(~16) of the asteroid population in near-Earth space Theirformation process is understood to be rotational fission caused bythe YORP effect Possible outcomes of post-fission dynamicsinclude contact binaries tightly and loosely bound binaries andasteroid pairs Radar images have been used to identify asteroidsatellites that orbit near the primary component but relatively littleattention has been paid to the detection of more distant satellitesWe are conducting a systematic search for faint andor distantsatellites in the Arecibo radar data archive To this end we havedeveloped a software package to identify candidate objects in radarimages and to differentiate these candidates from backgroundnoise using statistical analysis preliminary results of the searchwill be presented at the meeting Possible future applicationsinclude systematic measurements of asteroid radar properties (egDoppler and range extents) that could become part of an

1 11 1 2

1 1 12 2

1 1

1 23 1

1 11 1 1 1

1 1 1 1

88

automated data reduction pipeline

Author(s) M Oliver Bowman Jean-Luc MargotInstitution(s) 1 University of California Los Angeles

30821 ndash Serendipitous Observations of Asteroids bythe K2 MissionThe K2 mission is using the unique assets of the Kepler spacetelescope to perform long-baseline high-cadence high-precisionphotometry of targets selected by the community Unlike theoriginal Kepler mission the loss of two reaction wheels requires K2to point near the ecliptic plane As a result thousands of faintasteroids can be seen to pass through the target pixel masks thatare downlinked to earth after each ~75-day observing campaign Iwill show how these serendipitous observations of asteroids can beused to obtain lightcurves for faint (Vgt18) objects which areotherwise challenging to target from the ground In particular I willdemonstrate that the data are well-suited to identify small asteroidswith rotation periods near or below the ~2 hour spin barrier I willalso highlight the K2 data of other solar system bodies includingthe comets trans-Neptunian objects and Jupiter trojans for whichdedicated pixel masks have been (or will be) downlinked Owing toits ecliptic pointing and 14-meter diameter mirror K2 is offeringunique time-series photometry of small solar system bodies at aprecision which is unlikely to be rivaled by the future smaller-aperture photometric missions such as TESS and PLATO

Author(s) Geert BarentsenInstitution(s) 1 NASA Ames

309 ndash Formation of Planets Satellites andSmall Bodies30901 ndash Tidal Evolution of the Moon from aHigh-Obliquity Fast-Spinning EarthIn the conventional Giant Impact (GI) model of lunar formationthe Moon forms primarily from the debris of the impactor that islaunched into Earth orbit This is in conflict with extremelyEarth-like isotopic composition of the Moon All pre-2012 GImodels relied on the classic picture of lunar tidal evolution (egGoldreich 1965 Touma and Wisdom 1994) in which angularmomentum (AM) of the Earth-Moon system has been conservedsince lunar formation Cuk and Stewart (2012) showed that ahigh-AM Earth-Moon system can lose AM through the evectionresonance between the Moon and the Sun allowing for GIs that aremore conducive to incorporating Earth material into the MoonMore recently Lock et al (2015) show that a very-fast spinningEarth should be heavily coupled to the protolunar disk resulting inthe uniform composition of the Moon and Earths mantle Whilethe geophysical and geochemical benefits of the high-AM GI areclear further confirmation is needed that AM loss is both likely andconsistent with observed lunar orbit Not only does the evectionresonance not explain the current 5-degree lunar inclination butChen and Nimmo (2013) show that the conventional model oflunar spin evolution (Ward 1975) would lead to large-scaledamping of lunar inclination in the past The prospect of a pasthigh-inclination Moon requires complete revision of lunar tidalevolution models We use a numerical integrator that follows boththe orbit and the spin of the Moon and find that the Moon waslikely in non-synchronous rotation for a prolonged period duringCassini state transition implying inclination damping in excess ofthat in synchronous rotation We propose that the Moonscomposition and past large inclination can be explained by Earthspost-GI obliquity of about 70 degrees which led to instability oflunar orbit at the Laplace plane transition (Tremaine et al 2009)causing AM loss Earth obliquity reduction and lunar inclinationexcitation Subsequent secular resonance between Earths spin andthe Moons orbit further reduced Earths obliquity to its presentvalue

Author(s) Matija Cuk Sarah Stewart Simon Lock DouglasHamiltonInstitution(s) 1 Harvard U 2 SETI Institute 3 UC Davis 4University of Maryland

30902 ndash Dynamical Sequestration of theMoon-Forming Impactor in Co-Orbital Resonancewith EarthRecent concerns about the giant impact hypothesis for the origin ofthe moon and an associated ldquoisotope crisisrdquo are assuaged if theimpactor was a local object that formed near Earth and the impactoccurred relatively late We investigated a scenario that may meetthese criteria with the moon-forming impactor originating in 11co-orbital resonance with Earth Using N-body numericalsimulations we explored the dynamical consequences of placingMars-mass companions in various co-orbital configurations with aproto-Earth having 90 of its current mass We modeledconfigurations that include the four terrestrial planets as well asconfigurations that also include the four giant planets In both the4- and 8-planet models we found that a single additionalMars-mass companion typically remains a stable co-orbital ofEarth for the entire 250 million year (Myr) duration of oursimulations (33 of 34 simulations) In an effort to destabilize sucha system we carried out an additional 45 simulations that includeda second Mars-mass co-orbital companion Even with twoMars-mass companions sharing Earthrsquos orbit most of these models(28) also remained stable for the entire 250 Myr duration of thesimulations Of the 17 two-companion models that eventuallybecame unstable 12 impacts were observed between Earth and anescaping co-orbital companion The average delay we observed foran impact of a Mars-mass companion with Earth was 101 Myr andthe longest delay was 221 Myr Several of the stable simulationsinvolved unusual 3-planet co-orbital configurations that couldexhibit interesting observational signatures in plantetary transitsurveys

Author(s) Stephen J Kortenkamp William J HartmannInstitution(s) 1 Planetary Science Institute

30903 ndashThermal History and Volatile Partitioning betweenProto-Atmosphere and Interior of Mars Accreted in aSolar NebulaRecent precise Hf-W chronometry of Martian meteorites revealsthat Mars had likely reached the half of its present mass within 3Myr from the birth of the solar system (Dauphas and Pourmand2011) Hence the accretion is considered to almost proceed withinthe solar nebula associated with the capture of nebula gascomponents At the same time the impact degassing mayinevitably occur because impact velocity increases high enough forsuch degassing when a proto-planet gets larger than around lunarsize Thus we can expect the formation of a hybrid-type proto-atmosphere that consists of nebula gas and degassed oneThis study analyzes the thermal structure of this proto-atmospheresustained by accretional heating by building a 1D radiative-convective equilibrium model Raw materials of Mars are supposedto be volatile-rich on the basis of the geochemical systematics ofMars meteorites (Dreibus and Wanke 1988) The composition ofdegassed component comprised of H H O CH and CO isdetermined by chemical equilibrium with silicate and metal underthe physical condition of locally heated region generated by eachimpact (Kuramoto 1997) Degassed component lies beneath thenebula gas atmosphere at altitudes below the compositionalboundary height that would change depending on the amount ofdegassed component The accretion time is taken to be from 1 to 6MyrOur model predicts that the surface temperature exceeds theliquidus temperature of rock when a proto Mars grows larger than07 times of its present mass for the longest accretion time case Inthis case the magma ocean mass just after the end of accretion is02 times of its present mass if heat transfer and heat sources suchas short-lived radionuclides are neglected in the interior Thecorresponding amount of water dissolved into the magma oceanwould be around 18 times the present Earth ocean mass These

1 1

1

2 3 14

1 1

2 2 4

89

results suggest that the earliest Mars would be hot enough to formdeep magma oceans which promotes the core-mantledifferentiation and wet sufficient to make a deep-water ocean

Author(s) Hiroaki Saito Kiyoshi KuramotoInstitution(s) 1 Hokkaido University

30904 ndash Energy Dissipation in the Full N-BodyProblemWhen accounting for the dissipation of energy systems of finitedensity particles may achieve minimum energy resting states thatare unattainable in the classic point-mass treatment of the N-BodyProblem These aggregates serve as a model for rubble pileasteroids protoplanetary disk grains and planetary ring particlesAnalytical studies have shown all relative equilibria both stableand unstable as functions of angular momentum and energy forfew-N systems of spheres this approach likely applies to larger-Nsystems with mathematical and topological complexity increasingwith N and with the geometrical complexity of the constituentsUsing these studies as a guideline we simulate thousands ofrandomly generated small-N systems in order to determine thelikelihood of achieving one resting configuration over anotherprovided that multiple minimum energy configurations exist for aconstant angular momentum By restricting our aggregates to rigidparticles whose size is small enough to not compromise the rigidityof component bodies our study effectively probes the dynamical-mechanical properties of a wide array of small solar systemaggregates We outline the effects of energy dissipation on suchsystems primarily the effects of the coefficient of restitution whosevalue is the cumulative sum of mechanical deformations due toimpact in order to shed light on the early evolution of rubble-pilebodies

Author(s) Travis SJ Gabriel Daniel J ScheeresInstitution(s) 1 University of Colorado Boulder

30905 ndash Accretion of Cometary Nuclei in the SolarNebula Boulders Not PebblesComets are the most primitive bodies in the solar system Theyretain a largely unprocessed record of conditions in the primordialsolar nebula 456 Gyr ago including the initial accretion of dustand ice particles into macroscopic bodies Current accretion theorysuggests that ice and dust aggregates grew to pebble (cm) sizesbefore streaming instabilities and gravitational collapse broughtthese pebble swarms together as km-sized (or larger) bodiesRecent imaging of the nucleus of comet 67PChuryumov-Gerasimenko by the Rosetta OSIRIS camera team has revealed theexistence of ldquogoose bumprdquo terrain on the nucleus surface and liningthe interior walls of large ~200 m diameter and 180 m deepcylindrical pits These pits are believed to be sinkholes formedwhen near-surface materials collapse into voids within the nucleusrevealing the fresh comet interior on the walls of the pits Thegoose bump terrain consists of 3-4 m diameter ldquobouldersrdquorandomly stacked one on top of another We propose that theseboulders likely with an icy-conglomerate composition are thebasic building blocks of cometary nuclei This is the firstobservational confirmation of current accretion theories with thecaveat that rather than pebbles the preferred size range is 3-4 mboulders for objects formed in the giant planets region of the solarsystem The presence of icy grains beyond the solar nebulasnow-line and the large heliocentric range of the giant planetsregion likely contribute to the formation of these larger bouldersbefore they are incorporated into cometary nuclei This work wassupported by NASA through the US Rosetta Project

Author(s) Paul R Weissman Michael AHearnInstitution(s) 1 Planetary Science Institute 2 University ofMaryland

30906 ndash Formation of giant planetsrsquo cores by classicalplanetesimal accretionIn the core accretion scenario for formation of giant planetssolid-cores each with a roughly ten Earth masses first formfollowed by gravitational capture of massive gaseous envelopes

Although recent models favor solid core growth by accretion ofcentimeter-sized pebbles classical models in which embryos growby accretion of km-sized planetesimals have not been fullyunderstood We perform a suite of simulations for accretion ofsolid cores using a particle-based hybrid code that we have recentlydeveloped (Morishima 2015 Icarus 260 368) The code uses anN-body routine for interactions with planetary embryos while alarge number of small planetesimals are represented by a smallnumber of tracers and tracerndashtracer interactions are handled by astatistical routine The initial surface densities of both solid and gasare assumed to be seven times the minimum mass solar nebulaThe initial planetesimal size r_0 is varied from 100 m to 100 kmCollisions are assumed to result in either merging or hit-and-runbouncing depending on impact velocity (Genda et al 2012) whilefragmentation is ignored We find that embryos cannot usuallygrow to 10 Earth masses within 2 Myr although it can happen insome cases For the case of r_0 = 100 m embryos can grow up to6-7 Earth masses although they are quickly pushed toward thecentral star by planetesimals For r_0 = 100 km embryo massescan reach only two Earth masses within 2 Myr at best as theirgrowth is slow The case of r_0 = 1 km is found to be mostpromising as growth of embryos is fast while their inwardmigration is not very rapid

Author(s) Ryuji MorishimaInstitution(s) 1 University of California Los Angeles

30907 ndash Two- and Three-dimensional simulations ofatmospheric erosion by impactsOne of the key features of Earth-sized planets in this and othersystems is the presence or absence of an atmosphere Amechanism for atmsopheric loss post-formation is erosion byhypervelocity impacts by massive objects We are carrying outsimulations of the effects of hypervelocity impacts with the aim ofassessing the efficiency of the process and disentangling the effectsof impact erosion from other mechanisms such as thermal escapeFor our overall project we consider three types of planetsMars-type Earth-type and a super-Earth (8 M_earth) Surfaceatmospheric pressures are 1 10 and 100 bars Three diameters ofimpactors are considered (46 17 and 368 km) with impactvelocities of 2 4 6 and 8 times the escape velocity of the targetImpact simulations can be divided between local and globalcases depending on the geometry of the impact chiefly theimpactor size relative to the target planet and the depth of theatmosphere compared to the planets radius The calculationsdiscussed here are local the curvature of the planet and the radialdependence of the gravitational field are neglected The impactsimulations are carried out with the CTH code developed at SandiaNational Laboratory CTH is a highly advanced code widely used inthe planetary science community It utilizes adaptive meshrefinement to concentrate computational resources at locations ofphysical interest in the simulation such as shockfronts andmaterial interfaces It makes use of material strength models andadvanced tabular equations of state such as ANEOS and theSESAME library Post-impact analysis yields fluxes of materialmoving at escape speed or faster through the boundaries (chieflythe upper boundary at the exobase) we integrate the flux to get thetotal amount of escaping material Although we track three kinds ofmaterial (impactor target surface atmosphere) here we reportonly on the last (escaping atmosphere) We will present resultsfrom 2D and 3D simulations of impacts primarily for the largestimpactor (368 km diameter) This work was supported by NASAPlanetary Atmospheres Program award NNX14AJ45GComputations were carried out on the NASA Pleiades NAS clusterat NASA Ames

Author(s) D G Korycansky Kevin J Zahnle David CCatlingInstitution(s) 1 NASA Ames Reseatch Center 2 University ofCalifornia Santa Cruz 3 University of Washington

30908 ndash An experimental path to constraining theorigin of Jupiterrsquos Trojan asteroids by identifyingchemical fingerprints

1 1

1 1

1 2

1

2 13

90

We present an experimental study aimed at exploring thehypothesis suggested by recent dynamical models ndash that theJupiter Trojan asteroids originated in the outer solar system werescattered by the same instability responsibility for the radicalrearrangement of the giant planets and were subsequentlycaptured in their current location (eg Morbidelli et al 2005Nesvorny et al 2013) We seek to identify spectroscopic chemicaland isotopic properties that can tie the Trojan populations to theseevolutionary pathways providing experimental support ofdynamical models and providing testable hypotheses that can feedinto the design of experiments that might be performed onpotential future missions to these and other primitive bodiesWe present the results of experiments devised to explore thehypothesis that Kuiper Belt Objects (KBOs) represent the parentpopulations of the Trojan asteroids Numerous thin ice filmscomposed of select solar system volatiles (H O H S CH OHNH ) were grown in various mixtures to simulate compositionalchanges of icy bodies as a function of volatility and radial distanceof formation from the Sun Subsequent processing of these icybodies was simulated using electron irradiation and heating Visiblereflectance spectra show significant reddening when H S ispresent Mid-infrared spectra confirm the formation of non-volatilesulfur-containing molecules in the products of H S-containingices These experiments suggest that the presence of specificsulfur-bearing chemical species may play an important role in thecolors of both the KBOs and Trojans today Finally we discuss therole of the silicate component expected on the surface of the Trojanasteroids (Emery et al 2006) and the implications of a surfacecomposed of silicates in intimate contact with the nonvolatileorganic residues generated by ice irradiationThis work has been supported by the Keck Institute for SpaceStudies (KISS) The research described here was carried out at theJet Propulsion Laboratory Caltech under a contract with theNational Aeronautics and Space Administration (NASA) and at theCaltech Division of Geological and Planetary Sciences

Author(s) Jordana Blacksberg Ahmed Mahjoub MichaelPoston Mike Brown John Eiler Bethany Ehlmann KevinHand Robert W Carlson Robert Hodyss Ian WongInstitution(s) 1 California Institute of Technology 2 JetPropulsion Laboratory

30909 ndash Into coldness Where CO ice collisions ruleplanet formationIn protoplanetary disks CO appears in solid state beyond itssnowline at 10AU Being highly abundant it can affect theproperties of collisional growth in this region of the diskIn this work we carried out laboratory collision experiments with~100μm CO ice particles and a wall covered with a CO ice layer at80K Collision velocities varied between 0 - 25 msWe measured the threshold velocity of 004ms between stickingand bouncing and found onset of fragmentation for velocitiesabove 075ms Furthermore we deduced models for the coefficientof restitution and the fragmentation strength which are consistentwith the experimental dataWe conclude that CO ice shows a similar collisional behavior assilicate dust Compared to H O ice the sticking velocity is an orderof magnitude smaller One consequence is the loss of any bdquostickingadvantageldquo for H O ice particles if they are mantled with CO iceand planetesimal growth might be preferred in the zone betweenthe H O snowline and the CO snowline

Author(s) Grzegorz Musiolik Jens Teiser Tim Jankowski Gerhard WurmInstitution(s) 1 Universitaumlt Duisburg-Essen

30910 ndash Origin of the ices agglomerated by Comet67PChuryumov-GerasimenkoThe nature of the icy material accreted by comets during theirformation in the outer regions of the protosolar nebula is a majoropen question in planetary science Some scenarios of cometformation predict that these bodies agglomerated from clathratescrystallized in the protosolar nebula Concurrently alternativescenarios suggest that comets accreted amorphous ice originating

from the interstellar cloud Here we show that the recent N2COand ArCO ratios measured in the coma of the Jupiter family comet67PChuryumov-Gerasimenko by the ROSINA instrument aboardthe European Space Agencys Rosetta spacecraft can helpdisentangling between these two scenarios

Author(s) Olivier Mousis Jonathan I Lunine AdriennLuspay-Kuti Tristan Guillot Bernard Marty Peter Wurz Mohamad Ali-Dib Kathrin Altwegg Myrtha Haumlssig MartinRubin Pierre Vernazza Jack H WaiteInstitution(s) 1 Cornell University 2 CRPG-CNRS Universiteacutede Lorraine 3 Laboratoire dAstrophysique de Marseille 4Observatoire de la Cocircte dAzur 5 SWRI 6 Universiteacute de Franche-Comteacute 7 University of Bern

30911 ndash Comet missions and what can still be donefrom groundMuch of the knowledge on comet nuclei that has become availablesince the 1PHalley encounters in 1986 is based on spacemissions The nucleus shape and some surface parameters(topography morphology thermal optical behaviourcomposition) can directly be determined through remote-sensingmeasurements at close encounters At present 8 comets have beenvisited The information that became available from these missionsis discussed in view to its relevance for understanding solar systemformation Emphasis is put on comets 81PWild-2 9PTempel103Hartley-3 and 67PChuryumov-Gerasimenko Furthermoreoptions and prospects are discussed on how to benefit moreeffectively from spacecraft data If the knowledge coming fromspacecraft data is properly transferred to other comets it willprovide new means to distinguish whether differences betweencomets observed in the coma reflect differences of the nucleus orare related to different environmental conditions of the comets atthe time of observation This in turn has important implications tothe question of how and where comets were formed in the earlysolar system Some unknowns can only be addressed if data exist ofa statistically relevant number of comets hence may remain openfor a rather long time Options will be discussed on how toapproach these questions in the future

Author(s) Rita SchulzInstitution(s) 1 ESA Scientific Support Office

310 ndash Titans Surface and Atmosphere31001 ndash Geologic Conditions Required for the FluvialErosion of Titanrsquos CratersIn comparison to other icy satellites Titan has a small number ofimpact craters on its surface This suggests that it has a youngsurface andor erosional processes that remove craters from itssurface The set of geological conditions on Titan that would allowcraters to become unrecognizable by orbiting spacecraft such asCassini is unclear Initial results suggest that not all geologicconditions would allow for complete degradation of impact craterson Titan Using a landscape evolution model we explored a largerparameter space to determine the conditions under which arepresentative 40 km crater on Titan would be eroded We focusedon varying the values of parameters such as bedrock and regolitherodibility sediment grain size the weathering rate of the regolithand whether or not the regolith was saturated with liquidhydrocarbons We found that only after changing the saturationstate of the regolith mid-way through the simulation was it possibleto completely erode the crater Since there are few craters on Titanthis suggests that during Titanrsquos geological history there may havebeen varying quantities of liquid on its surface Titan is known tohave a dense atmosphere not unlike that of the Earth that couldallow for surface liquids to vary under a changing climate Theerosion rate could then also vary as a direct result of changingclimatic conditions

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Author(s) Rebeca Kinser Catherine Neish Alan Howard Paul Schenk Veronica BrayInstitution(s) 1 Florida Institute of Technology 2 Lunar andPlanetary Institute 3 University of Arizona 4 University ofVirginia 5 University of Western Ontario

31002 ndash Usefulness and Limitations of EnergyLimited Escape Titan and Other PlanetaryAtmospheresBecause thermal conduction and IR cooling are inefficient heattransfer processes adiabatic expansion leading to molecular escapeis often the dominant cooling process for energy deposited in theupper atmosphere of planetary bodies This led to the use of theenergy-limited escape (EL) approximation in which the loss rate isroughly proportional to the heating rate Q In applying the ELapproximation it was also frequently assumed that the adiabaticexpansion resulted in the gas outflow going sonic Johnson et al(2013) used molecular kinetic simulations of an atmosphere with aheated layer to show this was not necessarily the case andestimated a critical heating rate Q For Q greater than ~Q a sonicpoint formed below the exobase where the gas properties werecollision dominated As Q increased above ~Q sonic escape waseventually limited by the energy and number fluxes from the belowthe heated layer In that case adiabatic cooling did dominate upperatmosphere cooling but the escape rate did not increase withincreasing Q as predicted by the EL model Instead the escape rateremained nearly constant and the energy per molecule carried offincreased nearly monotonically with Q For heating rates fromabout twice Q to more than an order of magnitude lower themolecular escape rate was well approximated by the energy limitedrate but the upper atmospheric structure could not be described bya fluid model with a sonic point and escape was Jeans-like althoughthe Jeans expressions was often a poor approximation That ismolecules escape from well below the nominal exobase andcollisions remained important well above it (Tucker et al 20092013) resulting in enhanced-Jeans-like escape (Volkov et al2011ab Erwin et al 2013) Here we give a new expression for theescape rate produced by adiabatic cooling and expansion of theupper atmosphere and apply it to atmospheric loss from an earlyTitan atmosphere and related atmospheresRef ErwinJT et alIcarus 226375(2013)JohnsonRE etalApJL768 L4(6pp)ErratApJL77490(2013) TuckerOJ et alPSS571889 (2009) TuckerOJ et alIcarus 222149(2013)VolkovAN et alApJLett729L24(5pp)(2011a) ibid Phys Fluids23(2011b)

Author(s) Robert E Johnson Alexey N Volkov Orenthal JTuckerInstitution(s) 1 Univ of Virginia 2 University of Alabama 3University of Michigan

31003 ndash Titans Seasonal Haze Variation fromHST-STIS Image CubesFive STIS image cubes of Titan taken between 1997 and 2004constrain Titans seasonal haze variations during the season beforethe arrival of Cassini Each image cubes contains wavelengths530-1020 nm at 05 nm sampling with up to 005 arc-sec samplingin both spatial dimensions By comparing reflectivities betweendifferent dates stepping from the continuum wavelengths intomethane bands we determined the changing physical parametersand the size and phase of the variation including its altitudeWhile Titans north-south asymmetry is well know to change withTitans seasons HST and VIMS data showed its phasing to bespectrally dependent suggesting that the asymmetry does notchange simultaneously at all altitudesOur principal component analysis of the STIS cubes revealed thatthe north-south asymmetry is separated in two distinctcomponents a larger component describing changes at altitudesbelow 80+-20 km and a smaller component describing changes ataltitudes above 150+-50 km Altitudes in between did not showany change at any latitudeBoth components have a different phasing explaining phase shiftswith wavelengths noted above The high-altitude componentswitched the hemispherical asymmetry in 2001 The low-altitude

component had a rolling asymmetry change in 2002 at lowaltitudes in 2003 at mid latitude and in early 2004 at highaltitudesBoth components are due to variations of the aerosol opacity thatare probably driven by global dynamics The first component mayalso be partially due to a variation in the aerosol phase function andaerosol size which may be due to variable condensation of gasessuch as HCN onto aerosolsEquatorial latitudes have above average haze opacities at highaltitudes but below average at low altitudesA new haze model gives the haze opacity as function of altitudelatitude and time and fits the HST data well and even fits someCassini results obtained after the HST observations fairly well Itpredicts the next hemispherical asymmetry switch to occur in 2016at high altitudes and 2017 through 2018 at low altitudesDeails are currently being published in the Icarus special issue onTitan This research was supported by STScI through programAR12624

Author(s) Erich KarkoschkaInstitution(s) 1 Univ of Arizona

31004 ndash Titans aerosol optical properties with VIMSobservations at the limb of TitanThe study of Titan properties with remote sensing relies on a goodknowledge of the atmosphere properties The in-situ observationsmade by Huygens combined with recent advances in the definitionof methane properties enable to model and interpret observationswith a very good accuracy Thanks to these progresses we cananalyze in this work the observations made at the limb of Titan inorder to retrieve information on the haze properties as its verticalprofiles but also the spectral behaviour between 088 and 52 μmTo study the haze layer and more generally the source of opacitiesin the stratosphere we use som observation made at the limbe ofTitan by the VIMS instrument onboard Cassini We used a modelin spherical geometry and in single scattering and we accountedfor the multiple scattering with a parallel plane model that evaluatethe multiple scattering source function at the plane of the limbOur scope is to retrieve informations about the vertical distributionof the haze its spectral properties but also to obtain details aboutthe shape of the methane windows to disantangle the role of themethane and of the aerosolsWe started our study at the latitude of 55degN with a image taken in2006 with a relatively high spatial resolution (for VIMS) Ourpreliminary results shows the spectral properties of the aerosols arethe same whatever the altitude This is a consequence of the largescale mixing From limb profile between 09 and 52 μm we canprobe the haze layer from about 500 km (at 09 μm) to the ground(at 52 μm) We find that the vertical profile of the haze layer showsthree distinct scale heights with transitions around 250 km and350 km We also clearly a transition around 70-90 km that may bedue to the top of a condensation layer

Author(s) Pascal Rannou Benoit Seignovert PanayotisLavvas Steacutephane Lemouelic Christophe SotinInstitution(s) 1 JPLNASA 2 LPGNUniversiteacute de Nantes 3University of Reims-Champagne Ardenne

31005 ndash Microphysical Modeling of Titans DetachedHaze Layer in a 3D GCMWe investigate the formation and seasonal cycle of the detachedhaze layer in Titanrsquos upper atmosphere using a 3D GCM withcoupled aerosol microphysics The base of the detached haze layeris defined by a local minimum in the vertical extinction profile Thedetached haze is seen at all latitudes including the south pole asseen in Cassini images from 2005ndash2012 The layer merges into thewinter polar haze at high latitudes where the Hadley circulationcarries the particles downward The hemisphere in which the hazemerges with the polar haze varies with season We find that thebase of the detached haze layer occurs where there is a nearbalance between vertical winds and particle fall velocities Generallythe vertical variation of particle concentration in the detached hazeregion is simply controlled by sedimentation so the concentrationand the extinction vary roughly in proportion to air density This

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variation explains why the upper part of the main haze layer andthe bulk of the detached haze layer follow exponential profilesHowever the shape of the profile is modified in regions where thevertical wind velocity is comparable to the particle fall velocity Oursimulations closely match the period when the base of the detachedlayer in the tropics is observed to begin its seasonal drop in altitudeand the total range of the altitude drop However the simulationshave the base of the detached layer about 100 km lower thanobserved and the time for the base to descend is slower in thesimulations than observed These differences may point to themodel having somewhat lower vertical winds than occur on Titanor somewhat too large of particle sizes or some combination ofboth Our model is consistent with a dynamical origin for thedetached haze rather than a chemical or microphysical one Thisbalance between the vertical wind and particle fall velocities occursthroughout the summer hemisphere and tropics The particleconcentration gradients that are established in the summerhemisphere are transported to the winter hemisphere bymeridional winds from the overturning Hadley cell Our model isconsistent with the disappearance of the detached haze layer inearly 2014

Author(s) Erik J Larson Owen B Toon Robert A West AJames FriedsonInstitution(s) 1 Jet Propulsion Laboratory 2 University ofColorado

31006 ndash Comparing the Treatment of Spherical andFractal Particles in Titanrsquos Atmosphere using CARMAThe nature of Titanrsquos optically thick haze is of great interest in thestudy of its atmosphere In an attempt to further understand theparticle distribution and radiative properties of this haze we appliedthe Community Aerosol and Radiation Model for Atmospheres(CARMA) originally designed for Earth to simulate themicrophysical and radiative transfer properties of Titanrsquosatmosphere In the past the model treated the haze particles asspheres however it is more accurate to treat the haze particles asfractals (Lavvas et al 2010) We first simulated spherical particlesto verify the modelrsquos consistency with past studies (ie Toon et al1992) We then ran simulations considering fractal haze particlesIn both instances we considered a 600km atmosphere with aproduction zone centered at 300km from the surface Theseparticles initially 00013 microm in radius are then subject to verticaltransport and coagulation processes affecting the size number anddistribution of the particles Our results for both cases show thatfor wavelengths of 550nm the optical depth and extinction of theatmosphere rapidly decreases above 400km however there is agreater concentration of fractal particles at altitudes above 400kmthan spherical particles by at least two orders of magnitude Initialresults indicate that above 400km there were approximately 2x10fractal particlescm whereas there were only at most 1x10spherical particlescm corresponding with a greater cumulativeoptical depth of Titanrsquos atmosphere for fractal particles thanspherical particles The full effects of these results on thecumulative optical depth of the atmosphere are still being exploredThis work was funded by the NASA Outer Planets researchprogram

Author(s) Alexander Lanzano Erika BarthInstitution(s) 1 Laboratory for Atmospheric and Space Physics2 Southwest Research Institute

31007 ndash Soundings of Titans atmosphere by Cassiniusing the two-way radio occultation techniqueIn December 2011 the Ultra Stable Oscillator aboard Cassini failedand all subsequent radio occultations have been done using thetwo-way technique The two-way technique uses a highly stablefrequency reference on the ground rather than the on board USOA pure X band tone is transmitted to the spacecraft and that uplinksignal as Cassini receives it is used as the frequency reference forthe three returned S X and Ka band tones transmitted by thespacecraft On May 17 and June 18 of 2014 two occultations ofCassini by Titan occured during targeted Titan encounters T101and T102 and were done using the two-way technique for the first

time for Titan occultations We present the four soundings ofTitans atmosphere obtained from the resulting data using the twoway numerical inversion technique described in Schinder et alRadio Science 50 712 The ingress occultation on T101 occured at66 N latitude and egress is at 46 S On T102 ingress occured at 63N and 66 S latitude We will also place these results in context withthe earlier Titan occultations (Schinder et al Icarus 215 460Schinder et al Icarus 221 1020) done in one way mode

Author(s) Paul J Schinder F Michael Flasar EssamMarouf Richard French Aseel Anabtawi Elias BarbinisInstitution(s) 1 Cornell Univ 2 Jet Propulsion Laboratory 3NASA Goddard Space Flight Center 4 San Jose State University5 Wellesley College

31008 ndash Seasonal variations of temperature andcomposition at the Titan polesWe present an analysis of spectra acquired by CassiniCIRS at highresolution from October 2010 until September 2014 in nadir mode([1] amp refs therein) Since 2010 we have observed the appearance atTitanrsquos south pole of several trace species for the first time such asHC N and C H observed only at high northern latitudes beforeequinox We investigate here latitudes poleward of 50degS and 50degNfrom 2010 (after the Southern Autumnal Equinox) until 2014 Forsome of the most abundant and longest-lived hydrocarbons(C H C H and C H ) and CO the evolution in the past 4years at a given latitude is not significant within error bars untilmid-2013 More recently these molecules show a trend forincrease in the south This trend is dramatically more pronouncedfor the other trace species especially in 2013-2014 and at 70degSrelative to 50degS These two regions then demonstrate that they aresubject to different dynamical processes in and out of the polarvortex region For most species we find higher abundances at50degN compared to 50degS with the exception of C H CO C Hand HC N which arrive at similar mixing ratios after mid-2013While the 70degN data show generally no change except a smalldecrease for most species within 2014 the 70degS results indicate astrong enhancement in trace stratospheric gases after 2012 The663 cm HC N and the C H 674 cm emission bands appearedin late 2011early 2012 in the south polar regions and have sincethen exhibited a dramatic increase in their abundances At 70degSHC N HCN and C H have increased by 3 orders of magnitudeover the past 3-4 years while other molecules including C H C H and C H have increased less sharply (by 1-2 orders ofmagnitude) This is a strong indication of the rapid and suddenbuildup of the gaseous inventory in the southern stratosphereduring 2013-2014 as expected as the pole moves deeper intowinter shadow Subsiding gases that accumulate in the absence ofultraviolet sunlight evidently increased quickly since 2012 andsome of them may also be responsible for the reported hazedecrease in the north and its appearance in the south at the sametimeReference [1] Coustenis et al 2015 Icarus doi101016jicarus201508027

Author(s) Athena Coustenis Donald E Jennings RichardK Achterberg Georgios Bampasidis Panayiotis Lavvas ConorA Nixon Nicholas A Teanby Valeria Cottini Carrie MAnderson F Michael FlasarInstitution(s) 1 Faculty of Physics National and KapodistrianUniversity of Athens 2 GSMA Universiteacute Reims Champagne-Ardenne 3 Laboratoire drsquoEtudes Spatiales et drsquoInstrumentation enAstrophysique (LESIA) Observatoire de Paris PSL-ResearchUniv CNRS Univ Pierre et Marie Curie Paris 06 SorbonneUniv Univ Paris-Diderot 4 NASA Goddard Space Flight Center5 School of Earth Sciences University of Bristol

31009 ndash Titans Gas Behavior During the South PoleFallTitanrsquos southern middle atmosphere has been showing severalchanges since the start of fall season in 2009 In 2012 a large cloudappeared [1] [2] [3] temperatures became very low andcondensation and gas concentration at the South Pole increased[3] [4]

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In this work we will show the results of gas abundances retrievalsin the South Pole and their latitudinal variation changes as the coldseason evolved with timeWe analyzed several Cassini Composite InfraRed Spectrometer(CIRS [5]) mid-infrared observations of the South Pole acquiredduring 2013-2014 The data coordinates were converted in order tobe centered on the atmospheric pole and refer to the 1 mbar leveland not to the surface We first determine stratospherictemperatures from the same data and latitudes from the n band ofmethane centered around 1300 cm We retrieve the temperatureprofiles applying a radiative transfer forward model combined witha non-linear optimal estimation inversion method [6] We thenretrieve the main gases abundances and track their variation withlatitude using the same methodLatitudinal changes of the main Titanrsquos gases - HC N C H C H C H C H C H and HCN - show different trends in theSouthern polar regions over 2014 when winter was getting closerWe observe a ring-shape in some of the gas abundancedistributions with a local maximum peak around -75 deg oflatitude We also observe an increase of abundance of most of thegases toward the south pole as seen previously in the North duringthe winter The observed increase of benzene over the South Pole isdefinitely evident and strong References [1] West R A et al(2013) BAAS 45 30503 [2] Jennings D E et al (2012) ApJ 754L3 [3] de Kok R et al (2014) Nature 514 7520 65-67 [4]Vinatier S et al (2015) Icarus Volume 250 p 95-115 [5] Flasar etal (2004) Space Sci Rev 115 169ndash297 [6] Irwin PGJ et al(2008) J Quant Spectrosc Radiat Trans 109 1136ndash1150

Author(s) Valeria Cottini Conor A Nixon Richard KAchterberg Donald E Jennings Nicolas Gorius Patrick G JIrwinInstitution(s) 1 Catholic University of America 2 NASA GSFC3 University of Maryland 4 University of Oxford

31010 ndash Seasonal evolution of tropospheric H onTitan from the Cassini CIRS investigationFar-infrared Titan spectra obtained with the Composite Infra-RedSpectrometer on the Cassini spacecraft have been analyzed to studythe latitude distribution of H in the troposphere as well as itstemporal evolution over the period from March 2007 to August2014 This analysis shows that the previously observeddistribution characterized by a 30-70 enhancement at highNorthern latitudes has become more symmetrical since EquinoxHence the reversed pole-to-pole Hadley cell circulationestablished shortly after Equinox has been effective in equilibratingthe H mole fraction in both polar regions although not effectiveenough to produce a reversal of the polar enhancements probablybecause of a long time constant for the transport of air masses fromthe stratosphere to the troposhere

Author(s) Reacutegis CourtinInstitution(s) 1 LESIA - Observatoire de Paris

31011 ndash The Non-LTE Model of IR Emissions ofMethane in the TitansAtmosphereAbove about 400-450 km in Titans atmosphere the assumption oflocal thermodynamic equilibrium (LTE) breaks down for molecularvibrational levels of methane and various trace gases Above thisaltitude non-LTE significantly impacts the formation of infraredro-vibrational band emissions of these species observed in the limbviewing geometry We present detailed model of the non-LTE inmethane in the Titans atmosphere based on a new extendeddatabase of the CH4 spectroscopic parameters calculated for thisstudy We analyze vibrational temperatures of various 12CH4 and13CH4 levels as well as CH4 limb emissions in the 76 and 33 umspectral regions The impact on these emissions of many weakone-quantum and combinational bands which are missing incurrent databases is studied Implications for the non-LTEdiagnostics of the Cassini CIRS and VIMS measurements arediscussed

Author(s) Alexander Kutepov Ladislav Rezac ArtemFeofilov Michael Rey Andrei Nikitin Vladimir TyuterevInstitution(s) 1 Centre National de la RechercheScientifiqueEacutecole Polytechnique 2 Groupe de SpectromeacutetrieMoleacuteculaire et Atmospheacuterique UMR CNRS 3 Laboratory ofTheoretical Spectroscopy Institute of Atmospheric Optics 4 MaxPlanck Institute for Solar System Study 5 The Catholic Universityof America

31012 ndash Transmission windows in Titans lowertroposphere Implications for IR spectrometersaboard future aerial and surface missionsTitans thick atmosphere contains a 15 - 57 methane molefraction Methanes possession of fundamental overtone andcombination bands across much of the near and mid IR results insignificant absorption in the atmosphere across this spectralregion The consequence is spectral windowing such that Titanssurface can only be observed at a handful of methane transmissionwindows The narrow width of these windows for observationsfrom the top of the atmosphere (ToA) make only multispectralimaging of the surface possible This limits the information thatcan be gleaned about the surface composition which remainslargely unknown From ToA there is effectively zero transmissionat most wavelengths between the windows so that improvementsto the detectors or telescopes of IR spectrometers aboard orbital orflyby missions would not result in any appreciable widening of thewindows Only decreasing the methane column through whichobservations are made with a future mission operating near or onthe surface would result in any widening of the windows Wepresent a new line-by-line radiative transfer model to quantify thewindow widths for an IR spectrometer aboard an aerial or surfacemission to Titan We take spectral line parameters from theHITRAN database (Rothmann et al 2013) for methane and sixtrace gases include N2-N2 and N2-H2 collision-inducedabsorptions as measured by McKellar 1989 and the haze extinctionmeasured in situ by Huygens DISR The number of vertical layersin the model is chosen to correspond with the high cadence ofmeasurements of the physical conditions of Titans atmosphere byHuygens HASI We find that the transmission windows do notwiden appreciably for an aerial mission operating at altitudes onthe order of kilometers above the surface For surface missionsobserving at distances of order 10 m the windows widenconsiderably to encompass regions where absorptions fromhydrated minerals sulfates and pentane and higher order alkanescould be detected with hyperspectral observations We thus suggestthat infrared remote sensing from surface rather than aerialplatforms would be considerably better suited for characterizingTitans surface composition

Author(s) George D McDonald Paul M Corlies James JWray Jason D Hofgartner Sarah M Houmlrst Alexander GHayes Lucas R Liuzzo Jacob J BuffoInstitution(s) 1 Cornell University 2 Georgia Institute ofTechnology 3 Johns Hopkins University

31013 ndash Lifting Entry amp Atmospheric Flight (LEAF)System Concept Applications at Solar System BodiesWith an AtmosphereNorthrop Grumman and LrsquoGarde have continued the developmentof a hypersonic entry semi-buoyant maneuverable platformcapable of performing long-duration (months to a year) in situ andremote measurements at any solar system body that possesses anatmosphereThe Lifting Entry amp Atmospheric Flight (LEAF) family of vehiclesachieves this capability by using a semi-buoyant ultra-low ballisticcoefficient vehicle whose lifting entry allows it to enter theatmosphere without an aeroshell The mass savings realized byeliminating the heavy aeroshell allows significantly more payloadto be accommodated by the platform for additional sciencecollection and returnIn this presentation we discuss the application of the LEAF systemat various solar system bodies Venus Titan Mars and Earth Wepresent the key differences in platform design as well asoperational differences required by the various target

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environments The Venus implementation includes propulsivecapability to reach higher altitudes during the day and achieves fullbuoyancy in the mid-cloud layer of Venusrsquo atmosphere at nightTitan also offers an attractive operating environment allowingLEAF designs that can target low or medium altitude operationsalso with propulsive capabilities to roam within each altituderegime The Mars version is a glider that descends graduallyallowing targeted delivery of payloads to the surface or highresolution surface imaging Finally an Earth version could remainin orbit in a stowed state until activated allowing rapid responsetype deployments to any region of the globe

Author(s) Greg Lee Ronald Polidan Floyd Ross DanielSokol Steve WarwickInstitution(s) 1 Northrop Grumman

31014 ndash Titan Science with the James Webb SpaceTelescopeThe James Webb Space Telescope (JWST) scheduled for launch in2018 is an ambitious next-generation large-aperture (65 m) spaceobservatory focused on pushing the boundaries of infraredastronomy (06-280 μm) This long-wavelength focus gives it verysubstantial potential for solar system science since the thermalemissions from the surfaces and atmospheres of many planetsmoons and small bodies peak in this part of the spectrum Here wereport the findings of a task team convened to examine thepotential for Titan science using JWST These can be divided intofive broad areas (i) the surface especially the rotational lightcurve(ii) clouds in the lower atmosphere from direct imaging andnear-IR spectroscopy (iii) composition of the lower atmosphereespecially methane relative humidity (iv) composition of themiddle atmosphere including thermal and fluorescent emissionsfrom gases (v) hazes in the middle atmosphere including seasonalchanges in hemispheric contrast The capability of the major JWSTinstruments in each area is considered and limitations such aspotential saturation is noted and mitigation strategies (such assub-arraying) discussed Overall we find that JWST can makesignificant contributions to Titan science in many areas not least intemporal monitoring of seasonal change after the end of theCassini mission in 2017 in partnership with other next-generationobserving facilities (TMT GMT EELT ALMA)

Author(s) Conor A Nixon Richard Achterberg MateAdamkovics Bruno Bezard Gordon Bjoraker ThomasCornet Alexander Hayes Emmanuel Lellouch MarkLemmon Manuel Lopez Puertas Sebastien Rodriguez Christophe Sotin Nicholas Teanby Elizabeth Turtle RobertWestInstitution(s) 1 Cornell University 2 ESA ESAC 3 Instituto deAstrofisica de Andalucia 4 JHU APL 5 JPLCaltech 6 NASAGSFC 7 Observatoire de Paris 8 Texas AampM University 9Universite Paris-Diderot 10 University of Bristol 11 University ofCalifornia 12 University of Maryland

31015 ndash Vertical Profiles and Isotopic Ratios in HCNand its Isotopologues from ALMA Observations ofTitanThe photodissociation of methane (CH ) and molecular nitrogen(N ) provides the raw materials to create a suite of nitriles inTitans atmosphere the simplest and most abundant of these ishydrogen cyanide (HCN) The unprecedented sensitivity andspectral resolution of the Atacama Large MillimeterSub-millimeter Array (ALMA) permits the characterization of rotationaltransitions in this molecule and many of its isotopologues In thisstudy we leverage publicly available ALMA calibration observationsof Titan taken between April and July 2014 each lasting around160 seconds We report the detection of a new HCN isotopologueon Titan H C N and use this along with high signal-to-noiseobservations of HCN H CN HC N and DCN to determine theisotopic ratios C C N N and DH Isotopic ratios areknown to diverge throughout the solar system in planetaryatmospheres due to a variety of processes includingmass-dependent escape photochemistry and condensationTherefore accurate knowledge of isotopic ratios can provide

important constraints on models of the origin and evolution ofplanetary atmospheres

Author(s) Edward M Molter Conor A Nixon Martin ACordiner Steven B Charnley Patrick G J Irwin JosephSerigano Nicholas A TeanbyInstitution(s) 1 NASA Goddard Space Flight Center 2 OxfordUniversity 3 University of Bristol

31016 ndash Spectral Maps of Titanrsquos SurfaceTitanrsquos surface can be observed most clearly at 7 spectral regionsthat lie in between the strong methane bands in Titanrsquos spectrumWithin these rdquowindowsrdquo between 08 to 5 microns the surface isnonetheless obscured by methane and haze the latter of which isoptically thick at lower wavelengths Studies of Titanrsquos surface musteliminate the effects of atmospheric extinction which particularlyat high latitudes are not well constrained A more generalchallenge in the study of planetary surfaces is the extraction ofsubtle spectral features from a large quantity of low-resolutiondata which have dominant spectral trends upon which lessertrends reside This characteristic (a dominant spectral trend) isseen in Titanrsquos data images at all 7 wavelengths appear essentiallythe same with the bright terrain relatively bright at all wavelengthsand vise versa The question arises as to how to discern and mapthe smaller and orthogonal spectral trends of Titanrsquos surface inorder to investigate the composition Towards this goal we haveconstructed spectral maps of Titanrsquos surface by minimizing thecovariance matrix of the IF values (and separately the surfacealbedo) at the 7 window wavelengths This application of thePrincipal Components Analyses (PCA) yields the orthogonalspectral trends based on the variance of the IF values andseparately the surface albedos derived from radiative transfermodels Here we will present some of the interesting spectraltrends detected through the application of this method to smallsections of Titanrsquos surface

Author(s) Caitlin Ann Griffith Paulo Penteado Jake DTurner Tymon Khamsi Nicholas J MontielInstitution(s) 1 University of Arizona 2 University of Virginia

31017 ndash Titans Length-of-Day VariationsThe Cassini radar observation of Titan over several years show thatthe rotation period is slightly faster than the synchronous motion(Lorenz et al 2008 Stiles et al 2008 and 2011 Meriggiola 2012)The seasonal variation in the mean and zonal wind speed anddirection in Titanrsquos lower troposphere causes the exchange of asubstantial amount of angular momentum between the surfaceand the atmosphere (Tokano and Neubauer 2005 Richard et al2014) The rotation variation is affected by the influence of theatmosphere when we assume that Titan is a differentiated body andthe atmosphere interacts only with the outer layerIn this work we calculate variations of Titanrsquos length-of-day whenthe body is formed by two independent rotating parts and assumingthat friction occurs at the interface of them The tides areconsidered using the extension of two different theories -- theDarwin tide theory and Ferraz-Mellorsquos creep tide theory -- to thecase of one body formed by two homogeneous parts The resultsare compared and their differences are discussed

Author(s) Hugo Alberto Folonier Sylvio Ferraz-MelloInstitution(s) 1 IAG-USP

31018 ndash FT-IR measurements of mid-IR propene(C H ) cross sections and far-IR ammonia (NH ) lineintensitiesWe present spectroscopy measurements of propene (C H ) in themid-infrared and ammonia (NH ) in the far-infrared from twodifferent laboratory studies [1] For propene (CH -CH-CH aliaspropylene) which was detected in the stratosphere of Titan [Nixonet al 2013] temperature dependent cross sections in the 650 ndash1530 cm (65 ndash 153 μm) have been measured from a series ofhigh-resolution (00022 cm ) spectra of pure and N -mixturesamples of C H recorded at 150 ndash 296 K at Jet PropulsionLaboratory The observed spectral features cover the strongest v

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band with its outstanding Q-branch peak at 912 cm and threeother strong bands of v v and v at 990 1442 and 1459 cm respectively In addition we have generated a HITRAN-formatempirical lsquopseudoline list containing line positions intensities andeffective lower state energies by fitting all the observed spectrasimultaneously The results are compared with early work fromrelatively warm temperatures (278 ndash 323 K) [2] For ammonia(NH ) we obtained multiple sets of high-resolution spectra in theTHz and far-infrared region (50 ndash 650 cm ) at room temperatureusing AILES beamline at Synchrotron SOLEIL France (NH ) Inthis work we have measured line intensities for more than 4500transitions and made quantum assignments for ~2900 linesincluding ~960 very weak ΔK = 3 forbidden lines Final results willbe compared with the current databases (eg HITRAN GEISA)and ab initio calculations [Research described in this paper wasperformed at the Jet Propulsion Laboratory California Institute ofTechnology under contract with the National Aeronautics andSpace Administration Sung and Yu acknowledge the SynchrotronSoleil for the AILES beam line time]

Author(s) Keeyoon Sung Geoffrey C Toon Timothy JCrawford Shanshan Yu John C Pearson Fridolin KwabiaTchana Laurent Manceron Olivier PiraliInstitution(s) 1 CNRS-Univ Paris Est 2 Jet PropulsionLaboratory

311 ndash Jovian Planets Atmospheres andInteriors31101 ndash Uranus Persistent Patterns and Featuresfrom High-SNR Imaging in 2012-2014Since 2012 Uranus has been the subject of an observing campaignutilizing high signal-to-noise imaging techniques at KeckObservatory (Fry et al 2012 Astron J 143 150-161) High qualityobserving conditions on four observing runs of consecutive nightsallowed longitudinally-complete coverage of the atmosphere over aperiod of two years (Sromovsky et al 2015 Icarus 258 192-223)Global mosaic maps made from images acquired on successivenights in August 2012 November 2012 August 2013 and August2014 show persistent patterns and six easily distinguishedlong-lived cloud features which we were able to track for longperiods that ranged from 5 months to over two years Two atsimilar latitudes are associated with dark spots and move with theatmospheric zonal flow close to the location of their associated darkspot instead of following the flow at the latitude of the brightfeatures These features retained their morphologies and drift ratesin spite of several close interactions A second pair of features atsimilar latitudes also survived several close approaches Several ofthe long-lived features also exhibited equatorward drifts andlatitudinal oscillations Also persistent are a remarkablenear-equatorial wave feature and global zonal band structure Wewill present imagery maps and analyses of these phenomenaPMF and LAS acknowledge support from NASA PlanetaryAstronomy Program PMF and LAS acknowledge funding andtechnical support from W M Keck Observatory We thank those ofHawaiian ancestry on whose sacred mountain we are privileged tobe guests Without their generous hospitality none of ourgroundbased observations would have been possible

Author(s) Patrick M Fry Lawrence A Sromovsky Imke dePater Heidi B Hammel Phillip MarcusInstitution(s) 1 AURA 2 Univ of Wisconsin 3 University ofCalifornia

31102 ndash Uranusrsquo Hemispheric Asymmetries in PolarCloud and Circulation StructuresWe report on the north polar region of Uranus in thepost-equinoctial era Near-IR imaging with Keck 2 using NIRC2 in2012-2014 revealed numerous small bright features as well assmall dark features between 50 degrees N and the north poleTracking of these features yielded circulation patterns with theremarkable result that the region from 60 degrees to at least 83degrees rotates about the northern pole as a solid body with a drift

rate of 41 degreeshour westward relative to the interior(Sromovsky et al 2015 Icarus 258 192-223) For the south polethe same latitude region had dramatically different characteristicsas judged by 1986 Voyager and 2003 Keck observations Thesouthern region showed no discrete near-IR features detailedcirculation measurements in that region were based solely onlow-contrast features in re-analyzed Voyager images (Karkoschka2015 Icarus 250 294-307) They revealed a large gradient in driftrates with values reaching twice that seen in the correspondingnorthern regionThe north-south asymmetry in circulation and cloudstructuremorphology is surprising because the distribution ofupper tropospheric methane is relatively symmetric roughlyconstant over a region from 30 S to 30 N and then declining athigher latitudes in both hemispheres The methane distributionsuggests symmetric down-welling motion in both polar regionswhich would inhibit formation of condensation clouds there incontrast to the observed dichotomy Some asymmetry may be aneffect of seasonal forcing since the north versus south polarmeasurements were made during different seasons If so thenmajor changes can be expected in the north polar region as Uranusproceeds toward its 2030 northern summer solstice Hubble STISobservations expected in October of 2015 will further examine thevertical distribution and stability of the polar methane abundancesFuture high-resolution imaging with Earth-based facilities will beable to track circulation changes (unless the developing north polarhaze obscures trackable clouds)This research was supported by grants from NASAs PlanetaryAstronomy program and from the Space Telescope ScienceInstitute

Author(s) Heidi B Hammel Lawrence Sromovsky PatFry Imke de PaterInstitution(s) 1 AURA 2 U Wisconsin 3 UC Berkeley

31103 ndash Meridional trends in Neptunersquos backgroundaerosol structureWe will present retrieval results for Neptunersquos aerosol structure inregions free of discrete cloud features using data from the KeckOSIRIS integral field spectrograph and a two layer model for theaerosols We use a Markov chain Monte Carlo algorithm toperform a thorough search of the parameter space this analysisreveals a substantial decrease in the optical depth of the upperaerosol layer with increasing distance from the equator similar towhat is observed for the ldquoupper hazerdquo of Uranus in a simpletwo-cloud model (eg de Kleer et al 2015) We also tentativelyidentify an increase in the optical depth of the deeper aerosol layerfrom the equator to the south pole opposite to what is observed forUranus but in agreement with the conclusions of Karkoschka ampTomasko (2011) for Neptune from HST-STIS spectroscopy Finallywe will present our constraints on Neptunersquos methane profile andits latitude dependence and discuss the significance of theseresults in terms of Neptunersquos global circulation

Author(s) Statia H Luszcz-Cook Katherine de Kleer Imkede Pater Mate Adamkovics Heidi B HammelInstitution(s) 1 American Museum of Natural History 2AURA 3 University of California Berkeley

31104 ndash Composition of the Upper Atmosphere ofNeptuneIt has been previously asserted that sulfur-bearing species such asCS and SO2 may be present in the upper atmosphere of Neptuneas remnants of cometary impacts (Iino et al 2014) Based on theexample of the SL9 event on Jupiter CS in particular may be one ofthe most abundant tracers of past cometary impactsWe present the results of our search for spectral (sub)mmsignatures of HCN CS and SO in Neptunersquos stratosphereperformed on archival public data from the Atacama LargeMillimetersubmillimeter Array (ALMA) Neither CS or SO2 were detected on Neptune We estimated anupper limit on the SO stratospheric ratio significantly lower thanthe SO ratio in comets suggesting that S and O cannot both solelyoriginate from a cometary impact

-1

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Author(s) Elizabeth NanceInstitution(s) 1 St Marys College of Maryland

31105 ndash Exploring the connections between dark spotdynamics and zonal wind structure on UranusThe past several years have witnessed new observations revealingmore clouds and long-lived features in the atmosphere of UranusEach new set of images provides new cloud-tracking data and theopportunity to assess the structure of the zonal winds on UranusThis has led to a sequence of fits for the Uranian zonal winds withthe latest entries being those proposed in Sromovsky et al (2015)Karkoschka (2015) also provides a new view of the zonal winds butin this case through reanalyzing the Voyager II observations Whileall these profiles have in common features like a retrogradeequatorial jet the details of these profiles differ significantly Thesedifferences can be further accentuated when considering thevorticity profiles derived from these zonal winds As shown inLeBeau and Dowling (1998) and Hammel et al (2009)atmospheric simulations using different zonal vorticity profilessuggest that the vorticity gradient can affect the dynamics of darkspot vortices in the atmosphere Later work (Deng et al 2009) hasindicated that these dynamics may be further complicated by thepresence of cloud companion featuresTo further investigate these interactions some of the most recentzonal profiles are used in simulations of Uranus with the ExplicitPlanetary Isentropic Coordinate (EPIC) atmospheric model Byinducing vortices at different latitudes the effects of different zonalwind profiles on these features can be investigated A methanemicrophysics model is used to generate representative companionclouds The subsequent vortex and companion cloud motions canthen be compared to observations providing another tool in theeffort to understand possible changes in the zonal wind structure ofUranusReferencesLA Sromovsky et al Icarus 258192-223 2015E Karkoschka Icarus 250294-307 2015HB Hammel et al Icarus 201257-271 2009RP LeBeau and TE Dowling Icarus 132239-265 1998X Deng et al 1st AIAA Atmospheric and Space EnvironmentsConference AIAA-2009-3643 2009

Author(s) Raymond P Le Beau Csaba PalotaiInstitution(s) 1 Florida Institute of Technology 2 Saint LouisUniversity

31106 ndash Convection in Uranus and NeptuneIt is a common assumption of interior models that the outerplanets of our solar system are convective and that the internaltemperature distributions are therefore adiabatic If thisassumption is not correct the inferred internal structures of theseplanets can be different than typically thought Thereforeexploring this topic is crucial for planetary characterization Weinvestigate how the internal temperature profiles of Uranus andNeptune depend on the treatment of layered-convection We thenuse a set of possible temperature profiles associated with layered-convection together with density profiles derived from interiormodels that match the measured gravitational fields to derive thecompositions of the planets We find that the inferredcompositions of both Uranus and Neptune are not very sensitive tothe thermal profile In addition we show that calculating thethermal flux is important for understanding the energy transportmechanism in giant planets Finally we suggest that Neptunersquosinterior is just at the boundary between being convective orconductive and both configurations are consistent with its thermalflux while Uranusrsquo interior is mostly conductive This result isconsistent with recent dynamo models and useful forunderstanding the origin of the magnetic fields of the planets

Author(s) Morris Podolak Ravit Helled Gerald SchubertInstitution(s) 1 Tel Aviv University 2 UCLA

31107 ndash Revisiting the Galileo Probe results by astretched atmospheric modeThe Juno spacecraft will arrive at Jupiter in the late 2016 One of its

major scientific target is to measure the deep water abundancethrough its Microwave Radiometer (MWR) Prior to the arrival ofJuno the only observation of the weather layer of Jupiter was theGalileo probe (Niemann et al 1996 Wong et al 2004) whichreturned puzzling results In contrast to the detected 2 ndash 5 timesenrichment of CH NH and H S with respect to the solar valuesthe amount of water was severely subsolar Three dimensionalmodeling (Showman amp Dowling 2000) shows that dynamic drydowndrafts could create a huge trough in the material surface suchthat air flowing through the hot spots undergoes a temporaryincrease in pressure by a factor of 2 though it is still too small toexplain the Galileo probe results Inspired by the 3D modelingresult we constructed a stretched atmospheric model toparameterize the alteration of the thermodynamic state of air parcelby dynamics In our model an air parcel is initially in itsequilibrium condensation state and later has been dynamicallystretched to higher pressure modeled by a multiplicative factor SWhen S=1 the atmosphere is unaltered by dynamics representingthe equilibrium condensation model We found that when S=4the mixing ratios of H O NH and H S match all observationscoming from the Galileo probe site Thus this stretch parameterprovides a continuous representation of dynamic processes fromthe equilibrium condensation model to the Galileo probe resultsWe also show that the strength of stretch (S) can be retrieved fromJunoMWR limb darkening observations

Author(s) Cheng Li Andrew P Ingersoll Michael A JanssenInstitution(s) 1 Caltech 2 Jet Propulsion Laboratory

31108 ndash Updated Measurements of Saturnrsquos ZonalWind between 2004 - 2014 from Cassini ISS ImagesWe present updated zonal wind measurements of Saturn usingCassini ISS images taken between 2004 and 2014 We previouslyreported that there may be small seasonal changes in Saturnrsquoszonal wind profile but measurement uncertainties prevented usfrom making definite statements In our previous report we usedthe zonal standard deviation of the wind vectors as a proxy for themeasurement uncertainty However zonal standard deviationcontains contributions from both real spatial variations in the windspeed as well as uncertainties in the measurements This raised adifficulty in distinguishing small real changes in the wind fieldfrom the uncertainties in the measurement We have developed atechnique which isolates real spatial variations from measurementuncertainties by analyzing the correlation fields produced in thetwo-dimensional Correlation Imaging Velocimetry (CIV) cloud-tracking wind measurement method The CIV algorithm computesa wind vector by calculating the two-dimensional correlationbetween the pair of maps a peak in the correlation is judged to be amatch We determine the size shape and orientation of the peakby fitting an ellipse to the peak and calculating the areaeccentricity and orientation angle of the ellipse Combining thesemetrics provides a measure of the uncertainty associated withindividual wind vectors Vectors with smaller sharper morecircular peaks will have a smaller uncertainty than vectors withlarger flatter more elliptical peaks Using this new technique ournew measurements reveal small temporal changes in the zonalwind profiles Our work has been supported by NASA PATMNNX14AK07G and NSF AAG 1212216

Author(s) John J Blalock Kunio M Sayanagi Andrew PIngersoll Shawn P Ewald Ulyana A DyudinaInstitution(s) 1 California Institute of Technology 2 HamptonUniversity

31109 ndash On the Ammonia Absorption on SaturnThe ammonia absorption bands centered at wavelengths of 645and 787 nm in the visible spectrum of Saturn are very weak andoverlapped with more strong absorption bands of methaneTherefore the allocation of these bands is extremely difficult Infact the NH3 band 787 nm is completely masked by methane TheNH3 645 nm absorption band is superimposed on a relatively weakshortwave wing of CH4 band in which the absorption maximumlies at the wavelength of 667 nm In 2009 during the equinox onSaturn we have obtained the series of zonal spectrograms by

1

2 1

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97

scanning of the planet disk from the southern to the northern polarlimb Besides studies of latitudinal variation of the methaneabsorption bands we have done an attempt to trace the behavior ofthe absorption of ammonia in the band 645 nm Simple selection ofthe pure NH3 profile of the band was not very reliable Thereforeafter normalizing to the ring spectrum and to the level of thecontinuous spectrum for entire band ranging from 630 to 680 nmin the equivalent widths were calculated for shortwave part of thisband (630-652 nm) where the ammonia absorption is present anda portion of the band CH4 652-680 nm In any method ofeliminating the weak part of the methane uptake in the short wingshow an increased ammonia absorption in the northernhemisphere compared to the south This same feature is observedalso in the behavior of weak absorption bands of methane incontrast to the more powerful such as CH4 725 and 787 nm Thisis due to the conditions of absorption bands formation in theclouds at multiple scattering Weak absorption bands of methaneand ammonia are formed on the large effective optical depths andtheir behavior reflects the differences in the degree of uniformity ofthe aerosol component of the atmosphere of Saturn

Author(s) Victor G Tejfel A M Karimov P G Lyssenko GA KharitonovaInstitution(s) 1 Fessenkov Astrophysical Institute

31110 ndash Saturnrsquos fast spin determined from itsgravitational field and oblatenessKnowledge of the rotation period of a giant planet is crucial forconstraining its internal structure and atmosphere dynamicsHowever this physical property is not accurately determined in thecase of Saturn Spacecraft measurements of Saturnrsquos radioemission have revealed an uncertainty of nearly 10 minutes in itsrotation period Theoretical efforts to infer the rotation period haveincreased the uncertainty even more and at present Saturnrsquosrotation period is thought to be between sim 10h 32m and sim10h 47mWe present a new statistical optimization approach to determineSaturnrsquos rotation period We find that by using its measuredgravitational field and without imposing any constraints on theplanetary shape and internal density profile Saturnrsquos rotationperiod can be determined to within several minutes Moreover ifwe include limits based on the observed planetary shape andpossible density profiles the rotation period can be determined tobe 10h 32m 44s plusmn 46s The success of our method is confirmed byapplying it for Jupiter and reproducing exactly its measuredrotation period which is well-known

Author(s) Ravit Helled Eli Galanti Yohai KaspiInstitution(s) 1 Tel-Aviv University 2 The Weizmann Instituteof Science

31111 ndash Waves and eddies simulated byhigh-resolution Global Climate Modeling of Saturnstroposphere and stratosphereThe longevity of the Cassini mission permitted a detailed analysisof Saturns tropospheric storms an exceptional coverage ofSaturns Great White Spot (and subsequent stratosphericwarming) an assessment of the remarkable stability of thehexagonal polar jet and the seasonal monitoring of Saturnsequatorial oscillation Those observations open new questions thatadd to those related to the extent and forcing of Saturns alternatedjets One of the best step forward to progress is to build a GlobalClimate Model (GCM) for giant planets by coupling anhydrodynamical solver (dynamical core) with physical models forexternal forcings on the fluid We built a new GCM for Saturn bothversatile and powerful enough to resolve resolve the eddies arisingfrom hydrodynamical instabilities and forcing the planetary-scalejets extend from the troposphere to the stratosphere with goodenough vertical resolution and use optimized radiative transfer topredict seasonal tendencies over decade-long giant planets yearsTo that end we coupled our seasonal radiative model tailored forSaturn with DYNAMICO the next state-of-the-art dynamical corefor Earth and planetary climate studies in our lab using an originalicosahedral mapping of the planetary sphere which ensuresexcellent conservation and scalability properties in massively

parallel resources Using a new petaflops acquisition by CINES(France) we run our GCM for Saturn down to unprecedentedresolutions of 14deg and 18deg and to run sensitivity tests at 12degresolution Those high-resolution GCM runs show a detailed viewinto a striking variety of eddies and vortices on Saturn as well asthe arising of alternated banded jets the formation of a polarvortex the deformation of the polar jet into polygonal structuresWe will assess the nature and characteristics of both eddies andeddy-driven features in the troposphere and in the stratosphereusing spectral and dynamical analysis We will discuss how closeour simulations are to the observed features by Cassini and otherobservational campaigns and assess which processes are in need tobe improved in our GCM Perspectives for Jupiters atmosphericmodeling will also be described

Author(s) Aymeric Spiga Sandrine Guerlet YannMeurdesoif Mikel Indurain Ehouarn Millour ThomasDubos Meacutelody Sylvestre Jeacutereacutemy Leconte Thierry FouchetInstitution(s) 1 Laboratoire dAstrophysique de BordeauxCentre National de la Recherche Scientifique 2 LaboratoiredEtudes Spatiales et dInstrumentation en AstrophysiqueUniversiteacute Pierre et Marie Curie 3 Laboratoire de MeacuteteacuteorologieDynamique Centre National de la Recherche Scientifique 4Laboratoire de Meacuteteacuteorologie Dynamique Ecole Polytechnique 5Laboratoire de Meacuteteacuteorologie Dynamique Universiteacute Pierre etMarie Curie 6 Laboratoire des Sciences du Climat et delEnvironnement Commissariat agrave lEnergie Atomique

31112 ndash Polar Disturbance Surrounding a Long LivingCyclone in Saturnrsquos AtmosphereIn 2014 and 2015 a large lsquodark spotrsquo about 6000 km in length andlocated at planetocentric latitude +585deg (+63deg N planetographic)was tracked on the best ground-based amateur images of Saturnrevealing a long-lived feature an uncommon phenomenon inSaturnrsquos atmosphere Images captured by the Imaging ScienceSubsystem (ISS) onboard Cassini spacecraft showed the feature asa very contrasted dark spot in the MT3 filter and barely visible inthe deep sounding filters CB2 and CB3 On mid-May 2015ground-based observations obtained by amateur astronomersoperating small telescopes started to show a disturbance aroundthis dark spot Following the onset of this disturbance the drift ofthe dark spot remained unaltered and equal to the motion it hadpreviously but thedisturbance evolved zonally in a complex manner giving hints of akind of large scale phenomena in Saturnrsquos atmosphere of anunprecedented type Unfortunately the orbital path of the Cassinispacecraft was not appropriate to see details of the disturbance atthat time Images by the Hubble Space Telescope (HST) WFC3instrument obtained in directorrsquos time (DDT) allow us to describethe detailed dynamics of the disturbance while the study of itslong-term evolution is possible thanks to the efforts of thecommunity of amateur astronomers In this work we analyze thedynamics of the region before the start of the disturbance and thedynamics and evolution of the disturbance after its onset

Author(s) Teresa Del Rio Gaztelurrutia Agustiacuten Sanchez-Lavega Arrate Antuntildeano Ricardo Hueso Santiago Peacuterez-Hoyos Jose F Rojas Mike H Wong Amy A Simon Imke dePater Josep M Goacutemez-ForrelladInstitution(s) 1 Fundacioacute Observatori Esteve Duran 2 NASAGoddard Space Flight Center 3 University of California 4University of the Basque Country (UPVEHU)

31113 ndash Jupiters auroral-related thermal infraredemission from IRTF-TEXESAuroral processes on Jupiter can be observed at a large range ofwavelengths Charged particles of the solar wind are deflected byJupiterrsquos magnetic field and penetrate the atmosphere at highlatitudes This results in ion andor electron precipitation whichproduces emission at X-ray UV visible near-infrared and evenradio wavelengths These observations indicate three distinctfeatures of the aurora 1) filament-like oval structures fixed at themagnetic poles (~80degW (System III) in the south ~180degW in thenorth) 2) spatially-continuous but transient aurora that fill these

1 1 11

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oval regions and 3) discrete spots associated with the magneticfootprints of Io and other Galilean satellites Howeverobservations in the thermal infrared indicate the aurora alsomodify the neutral atmosphere Enhanced emission of CH isobserved coincident with the auroral ovals and indicatesheightened stratospheric temperatures possibly as a result of jouleheating by the influx of charged particles Stronger emission is alsoobserved of C H C H C H and even C H though previouswork has struggled to determine whether this is a temperature orcompositional effect In order to quantify the auroral effects on theneutral atmosphere and to support the 2016 Juno mission (whichhas no thermal infrared instrument) we have performed a retrievalanalysis of IRTF-TEXES (Texas Echelon Cross EchelleSpectrograph 5- to 25-μm) spectra obtained on Dec 11 2014 nearsolar maximum The instrument slit was scanned east-west acrosshigh latitudes in each hemisphere and Jupiterrsquos rotation was usedto obtain ~360deg longitudinal coverage Spectra of H S(1) CH C H C H and C H emission were measured at a resolvingpower of R = 85000 allowing a large vertical range in theatmosphere (100 ndash 0001 mbar) to be sounded Preliminaryretrievals of the vertical temperature profile from H S(1) and CHmeasurements at 60degN 180degW (on aurora) in comparison to60degN 60degW (quiescent) indicate the majority of auroral heatingoccurs from 10- to 1-μbar We plan on further testing thetemperature retrievals and adopting these results in thesubsequent retrievals of C H C H and C H to determinecompositional contrasts

Author(s) James Sinclair Glenn Orton ThomasGreathouse Leigh Fletcher Patrick IrwinInstitution(s) 1 Atmospheric Oceanic and Planetary PhysicsUniversity of Oxford 2 Jet Propulsion Laboratory 3 SouthwestResearch Institute 4 University of Leicester

31114 ndash Deriving Temperatures from the Homopauseof JupiterRecently Kim et al (Icarus 2015) derived homopausetemperatures from several places on the north and south polarregions of Jupiter by analyzing the 3-μm spectro-images of CH which were obtained using the Gemini Near-Infrared Spectrograph(GNIRS) The spectral resolution of the data was R~18000 whichis enough to resolve the sharp 3-μm emission lines of the P and Qbranches of CH From the next yearrsquos JUNO encounter withJupiter we are expecting low resolution spectra from JUNOrsquos IR2-5 μm spectrograph whose resolution is only R~300 at 3 μm Wewill present a method to derive homopause temperatures fromlow-resolution spectra utilizing the gross envelopes of the P Q Rbranch lines of CH We will discuss possible sciences extractedfrom the constructed maps of homopause temperatures over theauroral or non-auroral regions of Jupiter

Author(s) Sang J KimInstitution(s) 1 Kyunghee Univ

31115 ndash Photochemistry mixing and transport inJupiterrsquos stratosphere constrained by CassiniJupiterrsquos obliquity and eccentricity drive the seasonal forcing on itsatmosphere The seasonal variations on its stratospherictemperature through radiative heating and composition throughphotochemistry are smaller than for Saturn due to a lowerobliquity and eccentricity Although the physical conditions inthese two planets are different the stratospheric photochemistry isinitiated and controlled by the methane photolysis [1] We adapteda 2D (altitude-latitude) seasonal photochemical model of Saturn[2] to Jupiter We compare the seasonal effects on the atmosphericcomposition between these two planets We use previous 1Dphotochemical models for the vertical mixing efficiency [13] andrecent Cassini observations to constrain the meridional mixingefficiency and transport processes [456]Cassinirsquos flyby of Jupiter has allowed mapping its stratospherictemperature as a function of latitude [7] It has also revealed themeridional distribution of hydrocarbons [89] which weresuggested by earlier studies [104] Previous models suggest thatvertical mixing alone is not sufficient to reproduce the observations

of C H and C H [56] and that meridional mixing is needed Weshow that in addition to meridional mixing advective circulation isrequired to reproduce Cassini observations of C H Preliminaryresults from our model suggest an equator-to-pole circulation cellin Jupiterrsquos stratosphere around 30-001 mbarReferences[1] Moses et al 2005 JGR 110 8001[2] Hue et al 2015 Icarus 257 163-184[3] Gladstone et al 1996 Icarus 119 1-52[4] Kunde et al 2004 Science 305 1582-1587[5] Liang et al 2005 ApJ Lett 635 L177-L180[6] Lellouch et al 2006 Icarus 184 (2) 478-497[7] Simon-Miller et al 2006 Icarus 180 (1) 98-112[8] Nixon et al 2007 Icarus 188 47-71[9] Nixon et al 2010 PSS 58 1667-1680[10] Maguire et al 1984 Bulletin of the AAS 16 647-647

Author(s) Vincent Hue Franck Hersant Thibault Cavalieacute Michel DobrijevicInstitution(s) 1 LAB Universiteacute de Bordeaux CNRS UMR5804 2 LESIA Observatoire de Paris CNRS Universiteacute Paris 06Universiteacute Paris-Diderot

31116 ndash Saturns Stratospheric Water VaporDistributionWater is a sought after commodity in the solar system It is used asan indication of life planetary formation timescales and signaturesof past cometary impacts In Saturnrsquos atmosphere there are twosources of water an internal primordial reservoir that is confinedto the troposphere and an external source of unknown origin thatdelivers water to the stratosphere Potential sources ofstratospheric water include Saturnrsquos main rings (via neutral infallandor ions transported along magnetic field lines ndash ldquoRing Rainrdquo)interplanetary dust particles and the E-ring that is supplied withwater from the plumes of Enceladus Measuring the latitudinal andseasonal variation of H O on Saturn will constrain the source ofSaturnrsquos stratospheric waterCassinirsquos Composite InfraRed Spectrometer (CIRS) has detectedemission lines of H O on Saturn at wavelengths of 40 and 50microns CIRS also retrieves the temperature of the stratosphereusing CH lines at 77 microns Using our retrieved temperatureswe derive the mole fraction of H O at the 05-5 mbar level forcomparison with water-source models The latitudinal variation ofstratospheric water vapor will be presented as a first step inunderstanding the external source of water on Saturn Theobserved local maximum near Saturnrsquos equator supports either aneutral infall from the rings or a source in the E-ring We will lookfor secondary maxima at mid-latitudes to determine whether ldquoRingRainrdquo also contributes to the inventory of water in Saturnrsquos upperatmosphere

Author(s) Brigette E Hesman Gordon L Bjoraker RichardK Achterberg Paul N Romani Patrick GJ IrwinInstitution(s) 1 NASA GSFC 2 Oxford University 3 UnivMarylandNASA GSFC

31117 ndash Saturns stratospheric temperature andcomposition in 2015 from CassiniCIRS limbobservationsAs Cassinis solstice mission goes on our understanding ofSaturns atmospheric seasonal evolution continues to build upInfrared spectra acquired by CassiniCIRS in limb viewinggeometry in 2015 (end of spring in the northern hemisphere) areanalysed to retrieve vertical profiles of the stratospherictemperature and hydrocarbon abundances at several latitudesspanning tropical mid and high latitudesThese new measurements reveal how the equatorial oscillationcontinues to propagate downward with time and help bettercharacterize its period At 40N the previously observedtemperature anomaly and enrichment in hydrocarbons associatedwith the 2011 storm have since disappeared Compared to previousmeasurements acquired between 2005 and 2012 (Guerlet et alIcarus 2009 Sylvestre et al Icarus 2015) these new limbmeasurements also allow the study of the warming and cooling

4

2 2 2 4 2 6 6 6

th

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trends at different pressure levels associated with the change ofseasons These trends will be compared to predictions from aradiative climate model (Guerlet et al Icarus 2014)We also report the detection of benzene and aerosols at 77N whichconfirms that these compounds are enhanced in auroral regionscompared to low and mid latitudes as already derived from aprevious measurement at 80S in 2007 (Guerlet et al AampA 2015)The aerosol optical depth is found twice lower at 77N in 2015 (endof spring in N hemisphere) than that derived at 80S in 2007 (endof summer in S hemisphere) However whether this northsouthdifference stems from a permanent asymmetry or from a temporalvariation of the aerosol optical depth cannot be assessed from thesetwo measurements alone We will discuss implications for the roleof aerosols in the radiative forcing of the polar regions

Author(s) Sandrine Guerlet Thierry Fouchet BrigetteHesman Gordon Bjoraker Aymeric Spiga Melody SylvestreInstitution(s) 1 Laboratoire de Meteorologie Dynamique 2LESIA Observatoire de Paris 3 NASAGSFC

31118 ndash Effect of the 77 degree N Jet on SaturnrsquosHexagon Cloud MorphologyWe study how Saturnrsquos 77 degree N jet shapes the sharp edges ofthe hexagon The hexagonal morphology is shaped by ameandering jetstream that encircles the north pole of Saturn ataround 77 degree N planetographic latitude (Antunano et al 2015)Laboratory and numerical models have demonstrated that ajetstream could develop a six-sided shape in two different ways Inthe first which we call the vortex street model alternating pairs ofcyclonic and anticyclonic vortices form through shear instabilitiesand form a hexagonal pattern (Barbosa Aguiar et al 2010 Morales-Juberias et al 2011) In the second which we call the meanderingjet model a jetstream accompanied by a sharp gradient of potentialvorticity develops a meandering path without accompanyingvortices (Morales-Juberias et al 2015) The observed wind field ofSaturnrsquos hexagon is consistent with that of the meandering jetmodelIn the present study we first present Cassini ISS images of thehexagon captured using various filters and show that its cloudband boundary has a sharp contrast gradient along the path of thejetstream at 77 degree N We hypothesize that this sharp boundaryis a consequence of the transport barrier effect of the meanderingjetstream We further hypothesize that such sharp cloudboundaries cannot accompany a hexagonal jet formed through avortex street scenario We test our hypothesis by performingnumerical simulations using the EPIC atmosphere model (Dowlinget al 1998 2004) We use passive tracers to represent clouds in oursimulations to study the mixing across the jetstream in both thevortex street and meandering jet scenarios and test whether sharphexagonal cloud morphology could be reproduced by either of thescenariosOur research is supported by the NASA grants from Outer PlanetResearch (NNX12AR38G) Planetary Atmospheres(NNX14AK07G) Cassini Data Analysis (NNX15AD33G) programsand NSF Astronomy amp Astrophysics Program grant 1212216

Author(s) Kunio M Sayanagi Rauacutel Morales-Juberiacuteas John J Blalock Richard G Cosentino Andrew P Ingersoll Shawn P Ewald Ulyana A DyudinaInstitution(s) 1 California Institute of Technology 2 HamptonUniversity 3 New Mexico Institute of Mining and Technology

31119 ndash The Ongoing Evolution of a Long-LivedAnticyclone in Saturnrsquos Great Storm Region as seen byCassiniVIMSOnce the home of the enigmatic String of Pearls feature on Saturnthe region of 34 N was the scene of a titanic storm system thatswept around the planet in late 20102011 It left two things in itswake - a clear 5-μm bright zone around the planet and a curiousand persistent anticylone both of which remain to this day Wehave observed this anticyclone with CassiniVIMS since 2011 andfind that it seems to oscillate up and down latitudinally in thisstormy region Centered at 359 planetocentric latitude in May2011 it drifted northward to 378 in 2012 hovered near 37

through 2013 then settled southward back down to ~359 in2014 2015 has it once again drifting northward to ~37 It alsoperiodically interacts with the dark band above it exchangingmaterial in August 2013 and May 2015 We measured a progradezonal drift speed of ~22 ms in 2012 increasing as much as 60through 2013 then relaxing back to a more moderate ~15 ms in2014 as the oval sagged southward We expect its current 154 msrate to increase if it continues to drift northward in latitudefollowing the Voyager wind profile The feature has varied in size aswell spanning 49 x 32 in 2011 elongating zonally to 73 x 29by 2013 contracting in 2014 to an average of ~55 x ~29 andgrowing again to ~9 x ~4 in 2015 with an extended tendril ofmaterial streaming off one edge in May By August it wassymmetrically oval again It has varied in terms of cloudiness being~90 5-μm dark (obscured) in 2011 whereas by 2013 it wasmostly bright (clear) with a thin dark edge now returning to ~90dark in 2015 By utilizing night observations to isolate thermal fluxwe find that the mean 5-μm flux coming from the anticyclone hasdiminished steadily by about 50 since 2013 The storm latitude of~34 N itself has remained remarkably 5-μm bright since 2011 buthas begun to dim as well and is now bisected by a thin dark cloudyribbon which appears associated with the anticyclone We arecontinuing to monitor the evolution of the anticyclone and theStorm Region over time with CassiniVIMS

Author(s) Thomas W Momary Kevin H Baines SarahBadman Robert H Brown Bonnie J Buratti Roger N Clark Philip D Nicholson Christophe SotinInstitution(s) 1 Cornell University 2 Lancaster University 3NASAJet Propulsion Laboratory 4 Planetary Science Institute 5SSECUniversity of Wisconsin-Madison 6 University of Arizona

31120 ndash The search for atmospheric waves below theclouds of Jupiter using radio wavelength observationsWe observed Jupiter at 2 cm wavelength with the VLA in earlyFebruary 2015 This particular frequency is mostly sensitive tovariations in ammonia opacity and probes a depth between 1 and 2bars pressure below the visible cloud deck at 07 bars The dataacquired was projected into a cartographic map of the planetfollowing the technique of Sault et al (2004) The horizontalresolution is ~1500 km and we have examined the map foratmospheric waves on these and larger scales The map hasrevealed prominent features near 8N in the North Equatorial Beltwhere the 5 micron hotspot planetary wave feature also residesThe Great Red Spot is also prominent and has a noticeablemeridional asymmetry We will present our analysis of the spatialstructure for the entire map and best fit of its wave featurespectrumOur research is supported by NRAO and NMT

Author(s) Rick Cosentino Bryan Butler Bob Sault RaulMorales-Juberias Amy SimonInstitution(s) 1 New Mexico Institute of Mining andTechnology 2 NRAO 3 Solar System Exploration DivNASAGSFC

31121 ndash Numerical Modeling of Normal-ModeOscillations in Planetary Atmospheres Application toSaturn and TitanWe have developed a numerical model to calculate the frequenciesand eigenfunctions of adiabatic non-radial normal-modeoscillations in the gas giants and Titan The model solves thelinearized momentum energy and continuity equations for theperturbation displacement pressure and density fields and solvesPoissonrsquos equation for the perturbation gravitational potential Theresponse to effects associated with planetary rotation including theCoriolis force centrifugal force and deformation of the equilibriumstructure is calculated numerically This provides the capability toaccurately compute the influence of rotation on the modes even inthe limit where mode frequency approaches the rotation rate whenanalytical estimates based on functional perturbation analysisbecome inaccurate This aspect of the model makes it ideal forstudying the potential role of low-frequency modes for drivingspiral density waves in the C ring that possess relatively low pattern

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speeds (Hedman MM and PD Nicholson MNRAS 4441369-1388) In addition the model can be used to explore theeffect of internal differential rotation on the eigenfrequencies Wewill (1) present examples of applying the model to calculate theproperties of normal modes in Saturn and their relationship toobserved spiral density waves in the C ring and (2) discuss how themodel is used to examine the response of the superrotatingatmosphere of Titan to the gravitational tide exerted by SaturnThis research was supported by a grant from the NASA PlanetaryAtmosphere Program

Author(s) Andrew James Friedson Leon DingInstitution(s) 1 JPL 2 Summer Undergraduate ResearchFellow Caltech

31122 ndash Analysis of Cassini UVIS Extreme and FarUltraviolet Observations of Saturnrsquos AtmosphereThe atmosphere of Saturn is mainly composed of H and neutralatomic helium The study of He 584 Aring and H Lyman-αbrightnesses is interesting as the EUV and FUV (Extreme and FarUltraviolet) planetary airglow have the potential to yield usefulinformation about mixing and other important parameters in itsthermosphere Time variation asymmetries and polarenhancement of the airglow are also possible and analysis alreadyperformed using the public archived Cassini mission data sets haveshown we can solve some of the outstanding problems associatedwith these phenomena for SaturnSpecifically we have (1) examined epochal eddy mixing disparitiesin the Saturnian upper atmosphere and quantify temporal mixingvariations that may have occurred in the upper atmosphere ofSaturn as may be evidenced in Cassini mission data (2) quantifiedany enhanced mixing in the auroral regions of Saturn and (3)performed a robust study of Saturnian H Lyman-α brightness withthe view to discover any longitudinal H Lyman-α planetaryasymmetry or ldquobulgerdquo across the disc such as was discovered byVoyager at Jupiter indicative of the distribution of atomic H andaccounting for the observed flux and any variations from thenormal temperature profileWe have analyzed Cassini UVIS EUV and FUV airglow data fromSaturn using sophisticated photochemical and radiative transfermodels to investigate unexplained differences in the dynamicalprocesses operating within its upper atmosphere Powerful analysistechniques allow us to extract information on atmospheric mixingtemperatures and temporal changes due to the solar and seasonalcycles from the variations in distribution and intensity of airglowemissions that result We report on results of these efforts to date

Author(s) Christopher D Parkinson Tommi Koskinen Guillaume Gronoff Yuk L Yung Larry EspositoInstitution(s) 1 California Institute of Technology 2 LASPUniversity of Colorado 3 LPL 4 SCIENCE SYSTEMS ANDAPPLICATIONS INC 5 Univ of Michigan

31123 ndash Peeking into Saturns atmosphere the HSTlow-phase angle viewRecent Hubble Space Telescope WFC3 observations of Saturn haveprovided a low-phase angle view of the planet that nicelycomplements the higher phase angles and increased spatialresolution view from the Cassini spacecraft HST orbits wereperfectly timed for observing an atmospheric perturbation at polarlatitudes but they serendipitously captured other interestingfeatures at the Equatorial Zone (EZ) In this presentation we willdiscuss how the synergy between the CassiniISS and HSTWFC3observations provides an excellent way for peeking into Saturnsatmosphere and analyze the vertical distribution and properties ofthe particles and aerosols located in the lower stratosphere andupper troposphere of the planet We first discuss how CassiniISSobservations at a variety of phase angles constrain particleproperties and phase function in particular at the Equatorial ZoneThis had not been investigated since the early 1980s (Tomasko ampDoose 1984) more than a Saturnian year before the current workWe will also discuss the sizes and shapes of particles in thetroposphere as constrained by the retrieved phase function Withthis information the HSTWFC3 observations at 10 filters from

near-ultraviolet to the near-infrared provide substantialinformation on the vertical cloud structure and composition thefilters in and out of the intermediate and deep methane bands atthe near infrared give information on particle number densityaround the tropopause level (5-10 partcm ) and down to theammonia condensation level while near-ultraviolet and blue filterscharacterize the absorption of unknown chromophores in Saturnsatmosphere We will further show observations and radiativetransfer models of selected atmospheric features that haveimportant dynamical implications for understanding Saturnsatmospheric dynamics at the EZ and the Northern polaratmosphere In particular fast-moving features in the EZ withVoyager-era speeds seem to be located deeper (ge 2 bar) than thefeatures used for cloud-tracking since the pre-Cassini era (01 -1bar) thus simultaneously sounding for the first time threeseparate levels in the Equatorial region of the planet withsubstantially different wind speeds

Author(s) Santiago Perez-Hoyos JF Sanz-Requena ASanchez-Lavega R Hueso T del Riacuteo-Gaztelurrutia JFRojas AA Simon MH Wong I de Pater PGJ Irwin IIrizarInstitution(s) 1 Goddard Space Flight Center 2 Universidaddel Pais Vasco UPVEHU 3 Universidad Miguel de Cervantes 4University of California 5 University of Oxford

31124 ndash The Colors of SaturnVery little is known about the coloring agents or chromophoresthat color the clouds of Saturnrsquos belts and zones Although theclouds of Saturn are more muted in their coloration and do notexhibit the more striking variations seen among Jupiterrsquos beltszones and cyclonic storm features the physical processes thatrender Saturnrsquos clouds a yellowish hue are likely similar to those atwork on Jupiter Thus a comprehensive color study that includesboth Jupiter and Saturn is warranted to advance our understandingof chromophores in the giant planet atmospheres Here we reporton our efforts to characterize the colors of Saturnrsquos cloudsThis study involves the analysis of two imaging data sets thosefrom Cassinirsquos Imaging Science Subsystem (ISS) and Wide FieldPlanetary Camera 2 images taken with the Hubble Space Telescope(HST) The HST data were acquired in 1994 1998 2002 and 2004using eleven different filters spanning 255-973 nm After theimages were photometrically and geometrically calibrated we usedthem to create low resolution spectra for six different latituderegions the Equatorial Zone the Equatorial Belt the SouthEquatorial Belt the South Temperate Zone the South TemperateBelt and the South South Temperate Belt The Cassini ISS imageswere acquired in 2004 and 2011 using twelve different filtersspanning 258-938 nm and corresponding low resolution spectra ofthe same latitude regions were generated using the ISS images Wecompare these low resolution spectra to Saturnrsquos full-disk spectrum(Karkoschka E 1994 Icarus 111 174) to examine colors of discretelatitudes versus the full-disk spectrum of Saturn The extensivetemporal coverage afforded by the combination of the HST and ISSimages will enable us to explore possible seasonal variations inSaturnrsquos cloud colors Finally we examine the color evolution ofthe major 2011 storm on Saturn using the ISS dataThis work was supported by the Discovery Scholars Program inNMSUrsquos College of Arts and Sciences and NASArsquos Outer PlanetsResearch program through grant NNX12AJ14G

Author(s) Kayla DeVogel Nancy Chanover AlexanderThelenInstitution(s) 1 New Mexico State University

31125 ndash Photochemistry in Saturnrsquos Ring-ShadowedAtmosphere Modulation of Hydrocarbons andAerosolsCassini has been orbiting Saturn for over eleven years now Duringthis epoch the ring shadow has moved from covering much of thenorthern hemisphere (the solar inclination was 24 degrees) tocovering a large swath south of the equator and it continues tomove southward At Saturn Orbit Insertion in 2004 the projectionof the A-ring onto Saturn reached as far as 40N along the central

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meridian (52N at the terminator) At its maximum extent the ringshadow can reach as far as 48NS (58NS at the terminator) Thenet effect is that the intensity of both ultraviolet and visiblesunlight penetrating through the rings to any particular latitudewill vary depending on both Saturnrsquos axis relative to the Sun andthe optical thickness of each ring system In essence the rings actlike semi-transparent venetian blindsOur previous work examined the variation of the solar flux as afunction of solar inclination ie for each 725-year season atSaturn Here we report on the impact of the oscillating ringshadow on the photolysis and production rates of hydrocarbons(acetylene ethane propane and benzene) and phosphine inSaturnrsquos stratosphere and upper troposphere The impact of theseproduction and loss rates on the abundance of long-livedphotochemical products leading to haze formation are exploredSimilarly we assess their impact on phosphine abundance adisequilibrium species whose presence in the upper tropospherecan be used as a tracer of convective processes in the deeperatmosphereWe will also present our ongoing analysis of Cassinirsquos datasets thatprovide an estimate of the evolving haze content of the northernhemisphere and we will begin to assess the implications fordynamical mixing In particular we will examine how the nowfamous hexagonal jet stream acts like a barrier to transportisolating Saturnrsquos north polar region from outside transport ofphotochemically-generated molecules and hazeThe research described in this paper was carried out in part at theJet Propulsion Laboratory California Institute of Technologyunder a contract with the National Aeronautics and SpaceAdministration Copyright 2015 California Institute of TechnologyGovernment sponsorship is acknowledged

Author(s) Scott G Edgington Sushil K Atreya Eric HWilson Kevin H Baines Robert A West Gordon L Bjoraker Leigh N Fletcher Tom MomaryInstitution(s) 1 Goddard Space Flight Center 2 Jet PropulsionLaboratoryCalTech 3 University of Michigan 4 University ofOxford

31126 ndash Comprehensive Optical Coverage of Jupiterfor Spectral Comparison with NH SHThe distinct regions in Jupiters atmosphere ndash comprised of beltszones storms and the Great Red Spot ndash are thought to be coloredby unidentified chemical compounds called chromophores Thesemolecules created through Jupiters complex atmosphericchemistry may be responsible for the spectral slope and lack offeatures in the blue (shortwards of 500 nm) portion of Jupitersoptical spectrum Though many candidate compounds have beenproposed ndash such as ammonium hydrosulfide (NH SH) ndash theidentity of the coloring agent (or agents) remains elusive due to thesparse history of laboratory experiments conducted at appropriatetemperatures and pressures for Jovian conditions To build onprevious ground-based observations of Jupiter in the optical wehave obtained spectra with the Dual Imaging Spectrograph ndashmounted on the Astrophysical Research Consortium 35-metertelescope at Apache Point Observatory ndash over a wide portion of thevisible spectrum (~380-880 nm) by utilizing multiple centralwavelength settings These observations taken during February2013 and April 2015 cover multiple latitudinal regions on Jupiterincluding the Great Red Spot In this study we present the spectralcomparison of various regions in the Jovian atmosphere with datataken at the Cosmic Ice Laboratory at NASArsquos Goddard Space FlightCenter By exposing thin films of NH SH to varying amounts ofionizing radiation at Jovian temperature conditions we can analyzethe color and spectral changes of the ice This enables us toevaluate NH SH as a candidate chromophore throughcomparisons of spectral slope and features found in ground-basedoptical spectra of Jupiter This work was supported by NASArsquosOuter Planets Research Program through grant numberNNX12AJ14G

Author(s) Alexander E Thelen Nancy Chanover MarkLoeffler Reggie Hudson Amy SimonInstitution(s) 1 NASA Goddard Space Flight Center 2 NewMexico State University

31127 ndash Helium Rain and the Thermal Evolution ofthe Jovian PlanetsThe atmospheres of Jupiter and Saturn are observed to be depletedin helium relative to the protosolar nebula Coupled with Saturnsdrastic overluminosity compared to homogeneous thermalevolution models this constitutes strong evidence that HHephase separation is underway within the deep interiors of bothplanets We compute thermal evolution models for Jupiter andSaturn adopting a recent HHe phase diagram based on ab initiosimulations We find that if He settles efficiently despiteconvection then differentiation contributes a significant amount ofluminosity It also establishes a composition gradient that tends tostabilize the fluid against convection between one and a few millionbars A steeper-than-adiabatic temperature gradient is thusrequired to deliver the planets intrinsic flux a feature whichprofoundly affects the thermal history and which has not beenaddressed in previous studies In this quasistable region weconsider two possibilities (i) that overturning convection persistsbut with decreased efficiency due to the added expense of mixingup heavier material and (ii) that overturning convection gives wayto overstable double-diffusive convection We will judge thesuccess of the adopted phase diagram along with these generalizedtheories of heat transport in matching the observed luminositiesand atmospheric He abundances of Jupiter and Saturnsimultaneously The models we develop will be poised toincorporate the upcoming Juno and Cassini gravity fieldmeasurements

Author(s) Christopher Mankovich Jonathan J Fortney Kevin L Moore Nadine NettelmannInstitution(s) 1 University of California Santa Cruz

31128 ndash Measurement Of The DH Abundance OnJupiter And Saturn Using The CIRS Far-IRInterferometerIt is believed that the majority of the hydrogen on Jupiter andSaturn was obtained when the solar system formed about 46 Gyrago Consequently knowing the DH abundance on Jupiter andSaturn is essential to understanding stellar nucleosynthesis in ourgalaxy and subsequently the composition of the primordial nebulaThe Composite Infrared Spectrometer (CIRS) aboard the Cassiniorbiter made observations of Jupiter in 2000-2001 and has beenmaking continuous observations of Saturn since 2004 at a 05 cmspectral resolution and covering all latitudes Utilizing this highspectral resolution we have sought to model the HD rotationaltransitions (S0 S1 S2 S3 at 8923 17784 26525 and 35088cm respectively) to retrieve the DH ratios on Jupiter and Saturnand show preliminary fitting to the far-IR spectral region using theCIRS FP1 far-IR interferometer This work will provide a newmeasurement of DH on the giant planets that will give improvedconstraint on formation and evolution models of the solar systemand other planetary systems

Author(s) J D Roberts-Pierel C A Nixon G L Bjoraker BE Hesman R K Achterberg P GJ Irwin F M FlasarInstitution(s) 1 CRESSTUMBC 2 NASA GSFC 3 OxfordUniversity 4 UMCP

31129 ndash Convective Origin of Long-Lived Spots on theGiant PlanetsIn an earlier paper (Chan and Mayr 2013 Earth and PlanetaryScience Letters 371-372 212-219) we discussed the generation oflong-lived cyclones and anticyclones in fast rotating convectionzones The mechnism was applied to explain phenomenon like theGreat Red Spot on Jupiter In those calculations only singlecompact vortices could be formed and generation of anticyclonescould only be realized in high latitude Similar problems exist incalculations by other authors (eg Kapyla et al 2011 ApJ 74234-41 Julien et al 2012 Geophys Astrophys Fluid Dyn 106392-428 Guervilly et al 2014 JFM 758 407-435) Here wepresent new calculations with higher aspect ratio (widthdepth = 8)showing that (i) anticyclones can be generated in low latitude (225degree N in our case) (ii) multiple cyclonesanticyclones can formin a single computational domain Besides demonstrating the

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prevalence of long-lived vortices in fast rotating convection zonesthe result also shows that aspect ratio of the domain is animportant factor in simulation implying its effect also onlaboratory experiments

Author(s) Kwing Lam Chan Hans G MayrInstitution(s) 1 Applied Physics Laboratory 2 Space ScienceInstitute Macau University of Science amp Technology

31130 ndash Evaluation of Data Used for Modelling theStratosphere of SaturnPlanetary atmospheres are modeled through the use of aphotochemical and kinetic reaction scheme constructed fromexperimentally and theoretically determined rate coefficientsphotoabsorption cross sections and branching ratios for themolecules described within them The KINETICS architecture haspreviously been developed to model planetary atmospheres and isapplied here to Saturnrsquos stratosphere We consider the pathwaysthat comprise the reaction scheme of a current model and updatethe reaction scheme according the to findings in a literatureinvestigation We evaluate contemporary photochemical literaturestudying recent data sets of cross-sections and branching ratios fora number of hydrocarbons used in the photochemical scheme ofModel C of KINETICS In particular evaluation of newphotodissociation branching ratios for CH C H C H C H C H and C H and new cross-sectional data for C H C H C H C H C H C H and C H are considered Byevaluating the techniques used and data sets obtained a newreaction scheme selection was drawn up These data are then usedwithin the preferred reaction scheme of the thesis and applied tothe KINETICS atmospheric model to produce a model of thestratosphere of Saturn in a steady state A total output of thepreferred reaction scheme is presented and the data is comparedboth with the previous reaction scheme and with data from theCassini spacecraft in orbit around SaturnOne of the key findings of this work is that there is significantchange in the modelrsquos output as a result of temperature dependentdata determination Although only shown within the changes tothe photochemical portion of the preferred reaction scheme it issuggested that an equally important temperature dependence willbe exhibited in the kinetic section of the reaction scheme Thephotochemical model output is shown to be highly dependent onthe preferred reaction scheme used within it by this thesis Theimportance of correct and temperature-appropriate photochemicaland kinetic data for the atmosphere under examination isemphasised as a consequence

Author(s) Eleanor Sophie Armstrong Patrick G J Irwin Julianne I MosesInstitution(s) 1 Space Science Institute 2 University of Oxford

31131 ndash Distribution of alkali gases in Ios atmosphereThanks to high-sensitivity (sub)millimeter spectroscopicobservations KCl and NaCl in gas phase have been detected at lowconcentration levels in Ios atmosphere These molecules are likelyto be the main potassium and sodium carriers from the moon to itsenvironment Indeed potassium and sodium are known to bepresent in Ios neutral clouds and plasma torus which are believedto be fed from the moon itselfThe immediate sources of gaseous NaCl and KCl in Iosatmosphere are still unknown Based on thermochemicalarguments both molecules could be present in volcanic plumesTheir lifetime in gaseous form is predicted to be rather low (a fewhours) and a large portion of the emitted gas should quicklycondense on the ground Sputtering of surface condensates byhigh-energy particles may re-inject some of the condensates backin the atmosphere The efficiency of this process is highlydependant on the local atmospheric column densityWe present maps of NaCl and KCl emission distribution obtainedin 2012 and 2015 with the Atacama Large Millimter Array (ALMA)The distribution maps will be compared to the distribution ofvolcanic centers and Ios bulk atmosphere (SO ) in an attempt tocharacterize their immediate sources

Author(s) Arielle Moullet Emmanuel Lellouch MarkGurwell Raphael Moreno John Black Bryan ButlerInstitution(s) 1 Chalmers University of Technology 2 LESIA-Observatoire de Paris 3 NRAO 4 NRAO 5 SAO-Center ForAstrophysics

31132 ndash The effect of large-scale tropospheric stormson the ionospheres of giant planetsIt is well recognized that large-scale storms in the Earthtroposphere can leave observable signatures in the structure of theionosphere in terms of local electron density distributionTerrestrial numerical models indicate that thunderstorms canchange the electron density by more than an order of magnitude(Shao et al 2012) The atmospheres of Jupiter and Saturn areriddled by atmospheric storms of all scales Lightning has beensuccessfully detected in optical images in the tropospheres of bothplanets Our work presents a theoretical study of the dynamical andelectromagnetic effects of large thunderstorms on the verticalplasma distribution in the ionospheres of Jupiter and Saturn andcompares the predicted signatures with the available electrondensity profiles from the Galileo and the Cassini missions

Author(s) Katia MatchevaInstitution(s) 1 University of Florida

31133 ndash Laboratory Measurements and Modeling ofMolecular Photoabsorption Cross Sections in theUltraviolet Diatomic Sulfur (S ) and Sulfur Monoxide(SO)Our research program comprises the measurement and modelingof ultraviolet molecular photoabsorption cross sections with thehighest practical resolution It supports efforts to interpret andmodel observations of planetary atmospheres Measurement andmodeling efforts on diatomic sulfur (S ) and sulfur monoxide (SO)are in progressS Interpretations of atmospheric (Io Jupiter cometary comae)S absorption features are hindered by a complete lack oflaboratory cross section data in the ultraviolet We are working toquantify the photoabsorption spectrum of S from 240 to 300 nmbased on laboratory measurements and theoretical calculationsWe have constructed an experimental apparatus to produce astable column of S vapor at a temperature of 800 KHigh-resolution measurements of the absorption spectrum of thestrong B ndash X system of S were completed using the NISTVUV-FTS at Gaithersburg MD These measurements are beingincorporated into a coupled-channel model of the absorptionspectrum of S to quantify the contributions from individual bandsand to establish the mechanisms responsible for the strongpredissociation signature of the B ndash X system A successful coupledchannels model can then be used to calculate the B ndash X absorptionspectrum at any temperatureSO There has been a long-standing need for high-resolution crosssections of SO radicals in the UV and VUV regions where themolecule strongly predissociates for modeling the atmospheres ofIo and Venus and for understanding sulfur isotope effects in theancient (pre-O ) atmosphere of Earth We have produced ameasurable column of SO in a continuous-flow DC discharge cellusing SO as a parent molecule Photoabsorption measurementswere recently recorded with the high-resolution VUV-FTS on theDESIRS beamline of the SOLEIL synchrotron A number of strongpredissociated SO bands were measured in the 140 to 200 nmregion Weaker features associated with the SO B ndash X system weresimultaneously recorded allowing for an approximatedetermination of the VUV SO band f-values

Author(s) Glenn Stark James Lyons Hannah Herde Gillian Nave Nelson de OliveiraInstitution(s) 1 Arizona State University 2 BrandeisUniversity 3 NIST 4 Synchrotron SOLEIL 5 WellesleyCollege

31134 ndash Measurement and modeling of cold CHspectra from 21 to 27 micromA new study of CH line intensities and positions in the Octad

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region between 3600 and 4800 cm will be reported Nine spectrawere recorded with two Fourier transform spectrometers (theMcMath-Pierce FTS at Kitt Peak Observatory and the Bruker 125HR FTS at the Jet Propulsion Laboratory) using C-enrichedsamples at temperatures from 299 K to 80 K Line positions andintensities were retrieved by non-linear least squares curve-fittingprocedures and analyzed using the effective Hamiltonian and theeffective Dipole moment expressed in terms of irreducible tensoroperators adapted to spherical top molecules Quantumassignments were found for all the 24 sub-vibrational states of theOctad (some as high as J=10) Over 4750 experimental linepositions and 3300 line intensities were fitted with RMS standarddeviations of 0004 cm and 69 respectively A new linelist ofover 9600 measured positions and intensities from 3607 to 4735cm was produced with known quantum assignments given for45 of the features A manuscript and database has beensubmitted to J Quant Spectrosc Radiat Transfer

Part of the research described in this paper was performed at theJet Propulsion Laboratory California Institute of TechnologyNASA Langley Research Center and Connecticut College undercontracts and cooperative agreements with the NationalAeronautics and Space Administration The support of theGroupement de Recherche International SAMIA between CNRS(France) and RFBR (Russia) is acknowledged

Author(s) Linda R Brown Keeyoon Sung Timothy JCrawford Andrei V Nikitin Sergeri A Tashkun Michael Rey Vladimir G Tyuterev Mary Ann H Smith Arlan MantzInstitution(s) 1 Dept of Physics Astronomy andGeophysicsConnecticutt College 2 Groupe de SpectromeacutetrieMoleacuteculaire et Atmospheacuterique Universiteacute de Reims 3 JetPropulsion Laboratory California Institute of Technology 4Laboratory of Theoretical Spectroscopy VE Zuev Institute ofAtmospheric Optics 5 Science Directorate Nasa Langley

31135 ndash Probing the Depths of Jupiter and Saturn atFive-MicronsBoth Jupiter and Saturn exhibit dramatic and dynamic changes atall levels of their atmospheres as probed at various wavelengthsfrom the cloud tops to the deeper atmosphere and through theirstratospheric changes One common thread that is evident is thatmany changes observed in the clouds seem to be initiated in thedeep atmospheres via the five micron spectral window on bothplanets based on the data acquired from the NASAInfraRedTelescope Facility (IRTF) Jupiter exhibits traditional 5-micron hotspots however their inventory varies with time Similar features atother latitudes (eg SEB) may indicate a similar mechanism atplay Another region that underwent global change is recent fade ofthe northern component of the North Equatorial Belt (NEBn) Itwas characterized by visible brown barges along its northernboundary that are partially clear but not as cloudless as 5-micronhot spots On Saturn long-term studies of thermal emission fromits atmospheric window between 51 and 52 microns revealed adetailed cloud structure representing variations of cloud opacityaround Saturnrsquos 2-3 bar pressure region that we have tracked since1995 Since that time the zonal-mean narrow dark bands haveremained constant and are correlated with variations of zonal jetsWe have identified long-term variations in the cloud opacity that doappear to be correlated with seasonal changes with a decrease ofzonal-mean cloud opacity strongly correlated with seasonalchanges in insolation Substantial perturbations to the atmospherein the northern hemisphere from the great storm of 2010-2011have led to significant perturbations of the deep cloud fielddetected at 51 microns The clouding over of the central stormtrack during early 2011 was followed by a central clearing andclouding over of regions to its north and south making the stormlatitude the clearest atmospheric region ever detected We willdiscuss these trends and others over time in particular radiancesdiscrete features for Saturn and present a comparison of thesetrends with high quality images from the amateur community toidentify correlationanitcorrelations of the visible cloud field

Author(s) Padma A Yanamandra-Fisher Sara MGutierrez Anna Payne Glenn S Orton James SinclairInstitution(s) 1 CITJet Propulsion Laboratory 2 SpaceScience Institute 3 University of California Berkeley 4 WelleslyCollege

312 ndash Future Missions Instruments andFacilities31201 ndash Historical trends of participation of womenin robotic spacecraft missionsFor many planetary scientists being involved in a spacecraftmission is the highlight of a career Many young scientists hope toone day be involved in such a mission We will look at the scienceteams of several flagship-class spacecraft missions to look fortrends in the representation of groups that are underrepresented inscience We will start with The Galileo Cassini and Europamissions to the outer solar system as representing missions thatbegan in the 1980s 1990s and 2010s respectively We would alsolike to extend our analysis to smaller missions and those to targetsother than the outer solar system

Author(s) Julie A Rathbun Luke Dones Pamela Gay Barbara Cohen Sarah Horst Emily Lakdawalla JamesSpickard Moses Milazzo Kunio M Sayanagi Joanna SchugInstitution(s) 1 College of William and Mary 2 HamptonUniversity 3 Johns Hopkins 4 NASA Marshall 5 SIUE 6southwest Research Institute 7 The Planetary Society 8 Univ ofRedlands 9 USGS Flagstaff

31202 ndash NASAs Planetary Data System Support forthe Delivery of Derived Data Sets at the AtmospheresNodeNASArsquos Planetary Data System is charged with archiving electronicdata products from NASA planetary missions that are sponsored byNASArsquos Science Mission Directorate This archive currentlyorganized by science disciplines uses standards for describing andstoring data that are designed to enable future scientists who areunfamiliar with the original experiments to analyze the data and todo this using a variety of computer platforms with no additionalsupport These standards address the data structure descriptioncontents and media design The new requirement in the NASAROSES-2015 Research Announcement to include a DataManagement Plan will result in an increase in the number ofderived data sets that are being delivered to the PDS These datasets may come from the Planetary Data Archiving Restoration andTools (PDART) program other Data Analysis Programs (DAPs) orbe volunteered by individuals who are publishing the results oftheir analysis In response to this increase the PDS AtmospheresNode is developing a set of guidelines and user tools to make theprocess of archiving these derived data products more efficientHere we provide a description of Atmospheres Node resourcesincluding a letter of support for the proposal stage acommunication schedule for the planned archive effort productlabel samples and templates in extensible markup language (XML)documentation templates and validation tools necessary forproducing a PDS4-compliant derived data bundle(s) efficiently andaccurately

Author(s) Nancy J Chanover Reta Beebe LynnNeakrase Lyle Huber Shannon Rees Danae HornungInstitution(s) 1 New Mexico State Univ

31203 ndash The Planetary Data System--preparing for aNew DecadeIn order to improve NASArsquos ability to serve the Planetary ScienceCommunity the Planetary Data System (PDS) has beentransformed NASA has used the highly successful virtual institutemodel (eg for NASArsquos Astrobiology Program) to re-compete theScience Nodes within the PDS Structure The new institutestructure will facilitate our efforts within the PDS to improve botharchive searchability and product discoverability We will continue

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the adaption of the new PDS4 Standard and enhance our ability towork with other archivecuration activities within NASA and withthe community of space faring nations (through the IPDA) PDSscience nodes will continue to work with NASA missions from theinitial Announcement of Opportunity through the end of missionto define organize and document the data This process includespeer-review of data sets by members of the science community toensure that the data sets are scientifically useful effectivelyorganized and well documentedThe Science nodes were selected through a Cooperative AgreementNotice (NNH15ZDA006C) which specifically allowed thecommunity to propose specific archive concepts The selectednodes are Cartography and Imaging Sciences Rings-MoonSystems Planetary Geosciences Planetary Plasma InteractionsAtmospheres and Small Bodies Other elements of the PDS includean Engineering Node the Navigation and Ancillary InformationFacility and a small project officeThe prime role of the PDS is unchanged We archive and distributescientific data from NASA planetary missions astronomicalobservations and laboratory measurements NASArsquos ScienceMission Directorate sponsors the PDS Its purpose is to ensure thelong-term usability of NASA data and to stimulate advancedresearchIn this presentation we discuss recent changes in the PDS and ourfuture activities to build on the new Institute Near term effortsinclude developing a PDS Roadmap for the next decade lead by PDSChief Scientist Dr Ralph McNutt We are actively seekingcommunity involvement in this process Please visit our UserSupport Area at the meeting if you have questions accessing ourdata sets or providing data to the PDS or about the new PDSstructure

Author(s) Thomas H Morgan William P Knopf Edwin JGrayzeckInstitution(s) 1 NASA HQ 2 NASAGSFC

31204 ndash Metadata Design in the New PDS4 Standards- Something for EverybodyThe Planetary Data System (PDS) archives supports anddistributes data of diverse targets from diverse sources to diverseusers One of the core problems addressed by the PDS4 datastandard redesign was that of metadata - how to accommodate theincreasingly sophisticated demands of search interfaces analyticalsoftware and observational documentation into label standardswithout imposing limits and constraints that would impinge on thequality or quantity of metadata that any particular observer or teamcould supply And yet as an archive PDS must have detaileddocumentation for the metadata in the labels it supports or theinstitutional knowledge encoded into those attributes will be lost -putting the data at riskThe PDS4 metadata solution is based on a three-step approachFirst it is built on two key ISO standards ISO 11179 InformationTechnology - Metadata Registries which provides a commonframework and vocabulary for defining metadata attributes andISO 14721 Space Data and Information Transfer Systems - OpenArchival Information System (OAIS) Reference Model whichprovides the framework for the information architecture thatenforces the object-oriented paradigm for metadata modelingSecond PDS has defined a hierarchical system that allows it todivide its metadata universe into namespaces (data dictionariesconceptually) and more importantly to delegate stewardship for asingle namespace to a local authority This means that a missioncan develop its own data model with a high degree of autonomyand effectively extend the PDS model to accommodate its ownmetadata needs within the common ISO 11179 framework Finallywithin a single namespace - even the core PDS namespace -existing metadata structures can be extended and new structuresadded to the model as new needs are identifiedThis poster illustrates the PDS4 approach to metadata managementand highlights the expected return on the development investmentfor PDS users and data preparers

Author(s) Anne C Raugh John S HughesInstitution(s) 1 Jet Propulsion Laboratory 2 University ofMaryland

31205 ndash SPICE Supports Planetary ScienceObservation GeometrySPICE is an information system comprising both data andsoftware providing scientists with the observation geometryneeded to plan observations from instruments aboard roboticspacecraft and to subsequently help in analyzing the data returnedfrom those observations The SPICE system has been used on themajority of worldwide planetary exploration missions since thetime of NASAs Galileo mission to Jupiter Along with its freeprice tag portability and the absence of licensing and exportrestrictions its stable enduring qualities help make it a popularchoice But stability does not imply rigidityndashimprovements andnew capabilities are regularly added This poster highlights recentadditions that could be of interest to planetary scientistsGeometry Finder allows one to find all the times or time intervalswhen a particular geometric condition exists (eg occultation) orwhen a particular geometric parameter is within a given range orhas reached a maximum or minimumDigital Shape Kernel (DSK) provides means to computeobservation geometry using accurately modeled target bodies atessellated plate model for irregular bodies and a digital elevationmodel for large regular bodiesWebGeocalc (WGC) provides a graphical user interface (GUI) to aSPICE geometry engine installed at a mission operations facilitysuch as the one operated by NAIF A WGC user need have only acomputer with a web browser to access this geometry engine Usingtraditional GUI widgetsndashdrop-down menus check boxes radiobuttons and fill-in boxesndashthe user inputs the data to be used thekind of calculation wanted and the details of that calculation TheWGC server makes the specified calculations and returns results tothe users browserCosmographia is a mission visualization program This toolprovides 3D visualization of solar system (target) bodies spacecrafttrajectory and orientation instrument field-of-view cones andfootprints and moreThe research described in this publication was carried out at the JetPropulsion Laboratory California Institute of Technology under acontract with the National Aeronautics and Space Administration

Author(s) Charles Hall Acton Nathaniel J Bachman BorisV Semenov Edward D WrightInstitution(s) 1 Jet Propulsion Laboratory

31206 ndash NASAs Asteroid Redirect Mission (ARM)The National Aeronautics and Space Administration (NASA) isdeveloping a robotic mission to visit a large near-Earth asteroid(NEA) collect a multi-ton boulder from its surface and redirect itinto a stable orbit around the Moon Once returned to cislunarspace in the mid-2020s astronauts will explore the boulder andreturn to Earth with samples This Asteroid Redirect Mission(ARM) is part of NASArsquos plan to advance the technologiescapabilities and spaceflight experience needed for a humanmission to the Martian system in the 2030s Subsequent humanand robotic missions to the asteroidal material would also befacilitated by its return to cislunar space Although ARM isprimarily a capability demonstration mission (ie technologies andassociated operations) there exist significant opportunities toadvance our knowledge of small bodies in the synergistic areas ofscience planetary defense asteroidal resources and in-situresource utilization (ISRU) and capability and technologydemonstrations In order to maximize the knowledge return fromthe mission NASA is organizing an ARM Investigation Teamwhich is being preceded by the Formulation Assessment andSupport Team These teams will be comprised of scientiststechnologists and other qualified and interested individuals to helpplan the implementation and execution of ARM An overview ofrobotic and crewed segments of ARM including the missionrequirements NEA targets and mission operations will beprovided along with a discussion of the potential opportunitiesassociated with the mission

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Author(s) Paul Abell Dan Mazanek David Reeves BoNaasz Benjamin CichyInstitution(s) 1 NASA Goddard Space Flight Center 2 NASAJohnson Space Center 3 NASA Langley Research Center

31207 ndash The Whipple Mission Exploring the KuiperBelt and the Oort CloudWhipple will characterize the small body populations of the KuiperBelt and the Oort Cloud with a blind occultation survey detectingobjects when they briefly (~1 second) interrupt the light frombackground stars allowing the detection of much more distantandor smaller objects than can be seen in reflected sunlightWhipple will reach much deeper into the unexplored frontier of theouter solar system than any other mission current or proposedWhipple will look back to the dawn of the solar system bydiscovering its most remote bodies where primordial processes lefttheir imprintSpecifically Whipple will monitor large numbers of stars at highcadences (~12000 stars at 20 Hz to examine Kuiper Belt events asmany as ~36000 stars at 5 Hz to explore deep into the Oort Cloudwhere events are less frequent) Analysis of the detected events willallow us to determine the size spectrum of bodies in the Kuiper Beltwith radii as small as ~1 km This will allow the testing of models ofthe growth and later collisional erosion of planetesimals in theearly solar system Whipple will explore the Oort Cloud potentiallydetecting objects as far out as ~10000 AU This will be the firstdirect exploration of the Oort Cloud since the original hypothesis of1950Whipple is a Discovery class mission that was proposed to NASA inresponse to the 2014 Announcement of Opportunity The missionis being developed jointly by the Smithsonian AstrophysicalObservatory Jet Propulsion Laboratories and Ball Aerospace ampTechnologies with telescope optics from L-3 Integrated OpticalSystems and imaging sensors from Teledyne Imaging Sensors

Author(s) Charles Alcock Michael Brown Tom Gauron Cate Heneghan Matthew Holman Almus Kenter RalphKraft John Livingstone Ruth Murray-Clay Paul Nulsen Matthew Payne Hilke Schlichting Amy Trangsrud JanVrtilek Michael WernerInstitution(s) 1 Caltech 2 Harvard-Smithsonian CfA 3 JPL4 MIT 5 UC Santa Barbara

31208 ndash Trojan Tour and Rendezvous (TTR) A NewFrontiers Mission to Conduct the First DetailedReconnaissance of the Jupiter Trojan AsteroidsAmong the most potentially diagnostic but least exploredpopulations of small bodies are the Jupiter Trojan asteroids whichorbit at ~5 AU in the L4 and L5 Lagrange points of Jupiter TheTrojans provide a unique perspective on solar system historybecause their locations and physical compositional andmineralogic properties preserve evidence for importantgravitational interactions among the giant planets The locationsand orbital properties of more than 6200 Jupiter Trojans are nowknown but that is likely only a small fraction of a population of upto ~1e6 Trojans gt1 km in size The Trojans are hypothesized to beeither former KBOs scattered into the inner solar system by earlygiant planet migration and then trapped in L4 and L5 or bodiesformed near 5 AU in a more quiescent early solar systemImportant Planetary Decadal Survey questions that can beaddressed by studying the Trojans include (a) How did the giantplanets and their satellite systems accrete and is there evidencethat they migrated to new orbital positions (b) What is therelationship between large and small KBOs Is the smallpopulation derived by impact disruption of the large one (c) Whatkinds of surface evolution radiation chemistry and surface-atmosphere interactions occur on distant icy primitive bodies And(d) What are the sources of asteroid groups (Trojans and Centaurs)that remain to be explored by spacecraftHere we describe the Trojan Tour and Rendezvous (TTR) NewFrontiers mission concept which is designed to answer theseDecadal questions and to test hypotheses for early giant planetmigration and solar system evolution Via close flybys of many ofthese objects and orbital characterization of at least one large

Trojan TTR will enable the initial up-close exploration of thispopulation Our primary mission goals are to characterize theoverall surface geology geochemistry and mineralogy of theseworlds to characterize their internal structure and dynamicalproperties to investigate the nature sources and history of activityon these bodies and to explore the diversity of the broader Trojanasteroid population

Author(s) James F Bell Cathy Olkin Julie Castillo-RogezInstitution(s) 1 Arizona State Univ 2 Jet PropulsionLaboratory Caltech 3 Southwest Research Inst

31209 ndash REASON for EuropaThe science goal of the Europa multiple flyby mission is to ldquoexploreEuropa to investigate its habitabilityrdquo One of the primaryinstruments selected for the scientific payload is a multi-frequencymulti-channel ice penetrating radar system This ldquoRadar for EuropaAssessment and Sounding Ocean to Near-surface (REASON)rdquowould revolutionize our understanding of Europarsquos ice shell byproviding the first direct measurements of its surface character andsubsurface structure REASON will address key questionsregarding Europarsquos habitability including the existence of anyliquid water through the innovative use of radar soundingaltimetry reflectometry and plasmaparticles analyses Theseinvestigations require a dual-frequency radar (HF and VHFfrequencies) instrument with simultaneous shallow and deepsounding that is designed for performance robustness in thechallenging environment of Europa The flyby-centric missionconfiguration is an opportunity to collect and transmit minimallyprocessed data back to Earth and exploit advanced processingapproaches developed for terrestrial airborne data sets Theobservation and characterization of subsurface features beneathEuroparsquos chaotic surface requires discriminating abundant surfaceclutter from a relatively weak subsurface signal Finally themission plan also includes using REASON as a nadir altimetercapable of measuring tides to test ice shell and ocean hypotheses aswell as characterizing roughness across the surface statistically toidentify potential follow-on landing sites We will present a varietyof measurement concepts for addressing these challenges

Author(s) Gerald Wesley Patterson Don Blankenship Alina Moussessian Jeffrey Plaut Yonggyu Gim DustinSchroeder Krista Soderlund Cyril Grima Elaine ChapinInstitution(s) 1 Jet Propulsion Laboratory California Instituteof Technology 2 Johns Hopkins University Applied PhysicsLaboratory 3 University of Texas Institute for Geophysics

31210 ndash MarsCAT Mars Array of ionosphericResearch Satellites using the CubeSat AmbipolarThrusterThe MarsCAT (Mars Array of ionospheric Research Satellites usingthe CubeSat Ambipolar Thruster) Mission is a two 6U CubeSatmission to study the ionosphere of Mars proposed for the NASASIMPLeX opportunity The mission will investigate the plasma andmagnetic structure of the Martian ionosphere including transientplasma structures magnetic field structure and dynamics andenergetic particle activity The transit plan calls for a piggy back ridewith Mars 2020 using a CAT burn for MOI the first demonstrationof CubeSat propulsion for interplanetary travel MarsCAT willmake correlated multipoint studies of the ionosphere and magneticfield of Mars Specifically the two spacecraft will make in situobservations of the plasma density temperature and convection inthe ionosphere of Mars They will also make total electron contentmeasurements along the line of sight between the two spacecraftand simultaneous 3-axis local magnetic field measurements in twolocations Additionally MarsCAT will demonstrate theperformance of new CubeSat telemetry antennas designed at theUniversity of Houston that are designed to be low profile ruggedand with a higher gain than conventional monopole (whip)antennas The two MarsCAT CubeSats will have five scienceinstruments a 3-axis DC magnetometer adouble-Langmuir probea Faraday cup a solid state energetic particle detector (ScienceEnhancement Option) and interspacecraft total electron contentradio occulation experiment The MarsCAT spacecraft will be solar

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powered and equipped with a CAT thruster that can provide up to48 kms of delta-V which is sufficient to achieve Mars orbit usingthe Mars 2020 piggyback They have an active attitude controlsystem using a sun sensor and flight-proven star tracker fordetermination and momentum wheels for 3-axis attitude control

Author(s) Edgar Andrew Bering Lawrence S Pinsky Liming Li David Jackson Ji Chen Helen Reed MarkMoldwin Justin Kasper J P Sheehan James RichardForbes Thomas Heine Anthony Case Michael Stevens DavidG SibeckInstitution(s) 1 HarvardSmithsonian Center for Astrophysics2 NASAGSFC 3 Texas AampM University 4 University ofHouston 5 University of Michigan

31211 ndash Linear Ion Traps in Space The Mars OrganicMolecule Analyzer (MOMA) Instrument and BeyondHistorically quadrupole mass spectrometer (QMS) instrumentshave been used to explore a wide survey of planetary targets in oursolar system from Venus (Pioneer Venus) to Saturn (Cassini-Huygens) However linear ion trap (LIT) mass spectrometers havefound a niche as smaller versatile alternatives to traditionalquadrupole analyzersThe core astrobiological experiment of ESArsquos ExoMars Program isthe Mars Organic Molecule Analyzer (MOMA) onboard theExoMars 2018 rover The MOMA instrument is centered on alinear (or 2-D) ion trap mass spectrometer As opposed to 3-Dtraps LIT-based instruments accommodate two symmetrical ioninjection pathways enabling two complementary ion sources to beused In the case of MOMA these two analytical approaches arelaser desorption mass spectrometry (LDMS) at Mars ambientpressures and traditional gas chromatography mass spectrometry(GCMS) The LIT analyzer employed by MOMA also offers higherion capacity compared to a 3-D trap of the same volume redundantdetection subassemblies for extended lifetime and a link toheritage QMS designs and assembly logistics The MOMAengineering test unit (ETU) has demonstrated the detection oforganics in the presence of wt-levels of perchlorate effective ionenhancement via stored waveform inverse Fourier transform(SWIFT) and derivation of structural information through tandemmass spectrometry (MSMS)A more progressive linear ion trap mass spectrometer (LITMS)funded by the NASA ROSES MatISSE Program is being developedat NASA GSFC and promises to augment the capabilities of theMOMA instrument by way of an expanded mass range (ie 20 ndash2000 Da) detection of both positive and negative ions spatiallyresolved (lt1 mm) characterization of individual rock core layersand evolved gas analysis and GCMS with pyrolysis up to 1300deg C(enabling breakdown of refractory phases) The AdvancedResolution Organic Molecule Analyzer (AROMA) instrumentbeing developed through NASA PICASSO and ESA Research andDevelopment Programs combines a highly capable LIT front end(a la LITMS) with a high-resolution Orbitrap (a laCosmOrbitrap) mass analyzer to enable disambiguation of complexmolecular signals in organic-rich targets

Author(s) Ricardo Arevalo William Brinckerhoff PaulMahaffy Friso van Amerom Ryan Danell Veronica Pinnick Xiang Li Lars Hovmand Stephanie Getty Andrej Grubisic Fred Goesmann Herveacute CottinInstitution(s) 1 CRESST University of Maryland BaltimoreCounty 2 CRESST University of Maryland College Park 3Danell Consulting Inc 4 Laboratoire Interuniversitaire desSystegravemes Atmospheacuteriques 5 Linear Labs LLC 6 Max-Planck-Institut fuumlr Sonnensystemforschung 7 Mini-Mass Consulting 8NASA Goddard Space Flight Center

31212 ndash Exploring near Earth objectrsquos activity withcubesats low surface brightnessEver smaller Near Earth Objects (NEOs) continue to be discoveredwith most potentially hazardous ones already surveyed andongoing plans for space missions to deflect and mine them in thenear future These transitional objects in relatively unstable orbitshave recently experienced collisional or dynamical encounters that

have sent them to Earthrsquos vicinity Finding comet-like activity(sublimation and ejected dust) is necessary to understand theirorigin recent history and evolution Mommert et al (2014) haverecently discovered cometary activity on the third largest NEO(3552) Don Quixote using near-Infrared imaging fromSpitzerIRAC they detect both a coma and tail as extendedemission they identify as CO ice sublimation This activity hasgone unnoticed due to either sporadic activity or the relatively lowsurface brightness in optical wavelengths of light reflecting off dust26 magarcsec which necessarily imposes an extreme bias againstdetection We propose to find this activity directly in the optical bygoing above the atmosphereWe are developing a 6U Cubesat to carry a 20cm aperturetelescope The volume restrictions impose a deployment systemdesign for the telescope We will study the optimal mission andoptical setup for our goals including the feasibility of a novelcoronagraph to increase the sensitivity Detecting NEO activityrequires stability and low instrumental noise over many hoursAtmospherersquos varying point spread function (PSF) coupled withthe extended PSF of reflective telescopes lead us to propose todevelop the concept and technology to manage a refractivetelescope in space with the potential inclusion of a coronagraphoptimized for detecting faint features near bright targets Theexperiment considers targeting nearby NEOs and optimizingobservations for low surface brightness

Author(s) Cesar Fuentes Marcos Diaz Claudio Falcon Marcel ClercInstitution(s) 1 Universidad de Chile

31213 ndash Fast Transit Access to the Outer Solar SystemWe explore the capability of a VASIMR reusable probe ldquocatapultrdquoconcept to send a 4000-5000 kg spacecraft to Jupiter on aHohmann-like transfer orbit arriving in just 36 months elapsedtime The VASIMR performs a slingshot pass close to the Sunand uses the high level of available solar energy to produce asustained burst of high thrust Enough kinetic energy is providedto the probe to reach Jupiter orbit within 07-14 AU The Catapultrelease the probe with enough speed to reach Jupiter in threeyears and returns to Earth for another mission This studyidentifies the important parameters in the probe ejector operation(power level propellant mass payload release point distance ofclosest approach to the Sun) and scan these parameters tounderstand and optimize the capabilities of the proposed systemWe assume that the Catapult and its payload begin at the Earthrsquossphere of influence (SOI) and are coasting in the Earthrsquos orbitabout the Sun The VASIMR enginersquos power rating must matchthe peak power available when the spacecraft is closest to the SunThe solar array is assumed to be a planar array rather than aconcentrator since it will have to operate near the Sun where aconcentrator would overheat photovoltaic cells The feasibility ofnot releasing the payload and using the VASIMR to providethrust for the duration of the transfer orbit will also be examinedIn this scenario the VASIMR RF generators could serve doubleduty as radar RF sources

Author(s) Jared Squire Edgar Bering MatthewGiambusso Mark Carter Andrew Ilin Franklin R Chang DiazInstitution(s) 1 AdAstra Rocket Company 2 University ofHouston

31214 ndash Modeling momentum transfer by the DARTspacecraft into the moon of DidymosThe Asteroid Impact and Deflection Assessment (AIDA) mission isa joint concept between NASA and ESA designed to test theeffectiveness of a kinetic impactor in deflecting an asteroid Themission is composed of two independent but mutually supportivecomponents the NASA-led Double Asteroid Redirect Test (DART)and the ESA-led Asteroid Impact Monitoring (AIM) mission Thespacecraft will be sent to the near-Earth binary asteroid 65803Didymos which makes unusually close approaches to Earth in2022 and 2024 These close approaches make it an ideal target for akinetic impactor asteroid deflection demonstration as it will beeasily observable from Earth-based observatories The ~2 m 300

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kg DART spacecraft will impact the moon of the binary system at625 kms The deflection of the moon will then be determined bythe orbiting AIM spacecraft and from ground-based observationsby measuring the change in the moonrsquos orbital period A modelingstudy supporting this mission concept was performed to determinethe expected momentum transfer to the moon following impactThe combination of CTH hydrocode models analytical scalingpredictions and N-body pkdgrav simulations helps to constrainthe expected results of the kinetic impactor experimentTo better understand the large parameter space (including materialstrength porosity impact location and angle) simulations of theDART impact were performed using the CTH hydrocode Theresultant crater size velocity imparted to the moon andmomentum transfer were calculated for all cases For ldquorealisticrdquoasteroid types simulated DART impacts produce craters withdiameters on the order of 10 m an imparted Δv of 05ndash2 mms anda dimensionless momentum enhancement (ldquobeta factorrdquo) of107ndash5 for targets ranging from a highly porous aggregate to a fullydense rock These results generally agree with predictions fromtheoretical and analytical studies Following impact pkdgravsimulations of the system evolution track changes in the orbitalperiod of the moon and examine the effects of the shapes ofDidymos and its moon on the deflection These simulationsindicate that the shapes of the bodies can influence the subsequentdynamics of the moon

Author(s) Angela M Stickle Justin A Atchison Olivier SBarnouin Andy F Cheng Carolyn M Ernst Derek CRichardson Andy S RivkinInstitution(s) 1 Johns Hopkins University Applied PhysicsLaboratory 2 University of Maryland

31216 ndash Fourier transform spectroscopy for futureplanetary missionsThermal-emission infrared spectroscopy is a powerful tool forexploring the composition temperature structure and dynamics ofplanetary atmospheres and the temperature of solid surfaces Ahost of Fourier transform spectrometers (FTS) such as MarinerIRIS Voyager IRIS and Cassini CIRS from NASA Goddard havemade and continue to make important new discoveries throughoutthe solar systemFuture FTS instruments will have to be more sensitive (when weconcentrate on the colder outer reaches of the solar system) andless massive and less power-hungry as we cope with decreasingresource allotments for future planetary science instruments Withthis in mind NASA Goddard was funded via the PlanetaryInstrument Definition and Development Progrem (PIDDP) todevelop CIRS-lite a smaller version of the CIRS FTS for futureplanetary missions Following the initial validation of CIRS-liteoperation in the laboratory we have been acquiring atmosphericdata in the 8-12 micron window at the 12 m telescope at theGoddard Geophysical and Astronomical Observatory (GGAO) inGreenbelt MD Targets so far have included Earths atmosphere(in emission and in absorption against the moon) and VenusWe will present the roadmap for making CIRS-lite a viablecandidate for future planetary missions

Author(s) John C Brasunas Tilak Hewagama John RKolasinski Theodor KostiukInstitution(s) 1 NASAS GSFC 2 University of Maryland

31217 ndash Planetary Science with the StratosphericObservatory for Infrared Astronomy (SOFIA)The Stratospheric Observatory for Infrared Astronomy (SOFIA) iscurrently conducting the third annual Cycle of guest investigatorobserving programs Programs selected for the fourth Cycle (2016)were announced in October The planetary science community hasmade a significant showing in all proposal Cycles comprisingapproximately 15 of the time awarded in Cycles 1-3 SOFIA offersobservers access to the complete infrared spectrum with much lessatmospheric absorption than from even the finest ground-basedtelescope sites New capabilities include high-resolutionspectroscopy in the mid-infrared with the Echelon-Cross-EchelleSpectrograph (EXES) that allows spectroscopy of molecules from

narrow stratospheric lines of planetary atmospheres plus imagingspectroscopy with the Field Imaging Far-Infrared LineSpectrometer (FIFI-LS) capable for example of simultaneousobservations in 9 spatial pixels in each of two far-infrared spectrallines Also the FLITECAM near-IR and FORCAST mid-IR camerasinclude grisms that allow moderate-resolution spectral imaging atwavelengths inaccessible from the ground and HIPO and FPI+high-speed photometric imagers are capable of high-SNmeasurements of stellar occultations and exoplanet transitsPlanetary science targets observed to date include comets ISONand PanSTARRS main belt asteroids Mars Jupiter NeptunePluto Europa exoplanets and debris disks This poster willshowcase science highlights give details regarding the SOFIAobservatory and instrument capabilities and present observingprogram statistics

Author(s) Dana E Backman William T ReachInstitution(s) 1 SOFIA

31218 ndash Capabilities of the Thirty-Meter Telescope(TMT) for Solar System AstronomyThe TMT will consist of a 30-m filled-aperture segmented primarymirror and will include non-sidereal rate tracking capabilities forobserving Solar System objects Its sensitivity will be 14 times largerthan that of 8-m class telescopes for seeing-limited observations-up to 200 times larger for background limited adaptive optics (AO)observations- and will allow high angularspatial resolution withdiffraction-limited capability in the near infrared AO guiding willaccommodate faint small angular size solar system objects to serveas natural guide stars for non-sidereal observations For Kuiperbelt objects (KBOs) on-instrument wavefront sensors can crawlthe field-of-view to look for background natural stars that can beused for tiptilt correction We will describe the maincharacteristics of the Thirty Meter Telescope its first lightinstrumentation suite and the most relevant science-drivenrequirements for its design emphasizing the strengths of the TMTfor Solar System astronomical research Some real-case scenariosof sensitivities for solar system targets will be presented for thefirst-light instrumentsComplementary information about TMT and the opportunities itoffers for planetary science research will be presented at thismeeting by Dumas et al and at the TMT Solar System Town Hallevent on TuesdayThe international TMT partnership includes Canada China IndiaJapan Caltech the University of California and Funding is alsoprovided by the Gordon and Betty Moore Foundation AURA is anAssociate Member of TMT on behalf of the US nationalcommunity Through a cooperative agreement with the NSF TMTand a US TMT Science Working Group are developing a model forpotential US national partnership in the TMT

Author(s) Angel Otarola Christophe Dumas KarenMeech Tomohiko Sekiguchi Warren Skidmore Feng Tian Tony Travouillon Michael H Wong Brent Ellerbroek LucSimardInstitution(s) 1 Institute for Astronomy University of Hawaii2 Hokkaido University of Education 3 TMT InternationalObservatory 4 Tsinghua University 5 University of California atBerkeley

31219 ndash The TMT International Observatory A quickoverview of future opportunities for planetary scienceexplorationThe construction of the Thirty-Meter-Telescope InternationalObservatory (TIO) is scheduled to take about eight years withfirst-light currently planned for the horizon 202324 and start ofscience operations soon after Its innovative design the unequalledastronomical quality of its location and the scientific capabilitiesthat will be offered by its suite of instruments all contribute toposition TIO as a major ground-based facility of the next decadeIn this talk we will review the expected observing performances ofthe facility which will combine adaptive-optics correctedwavefronts with powerful imaging and spectroscopic capabilitiesTMT will enable ground-based exploration of our solar system -

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and planetary systems at large - at a dramatically enhancedsensitivity and spatial resolution across the visible andnear-thermal- infrared regimes This sharpened vision spanningthe study of planetary atmospheres ring systems (cryondash)volcanicactivity small body populations (asteroids comets trans-Neptunian objects) and exoplanets will shed new lights on theprocesses involved in the formation and evolution of our solarsystem including the search for life outside the Earth and willexpand our understanding of the physical and chemical propertiesof extra-solar planets complementing TIOs direct studies ofplanetary systems around other starsTIO operations will meet a wide range of observing needsObserving support associated with classical and queue modeswill be offered (including some flavors of remote observing) TheTIO schedule will integrate observing programs so as to optimizescientific outputs and take into account the stringent observingtime constraints often encountered for observations of our solarsystem such as for instance the scheduling of target-of-oportunityobservations the implementation of short observing runs or thesupport of long-term key-science programmesComplementary information about TIO and the opportunities itoffers for planetary science research will be presented at thismeeting by Otarola et al in addition to the TMT Solar SystemTown Hall event on Tuesday

Author(s) Christophe Dumas Sandra Dawson AngelOtarola Warren Skidmore Gordon Squires TonyTravouillon Thomas K Greathouse Jian-Yang Li Junjun Lu Frank Marchis Karen J Meech Michael H WongInstitution(s) 1 California Institute of Technology 2 PlanetaryScience Institute 3 SETI Institute 4 Southwest Research Institute5 Thirty-Meter-Telescope International Observatory 6 UCBerkeley 7 University of Hawaii

31220 ndash The NASA Infrared Telescope Facility (IRTF)New Observational CapabilitiesThe NASA Infrared Telescope Facility (IRTF) is a 30-m infraredtelescope located at an altitude of 42 km near the summit ofMauna Kea on the island of Hawaii The IRTF was established byNASA to support planetary science missions Current instrumentsinclude (1) SpeX a 07-53 μm moderate resolution spectrographwith a slit-viewing camera that is also an imager (2) MORIS ahigh-speed CCD imager attached to SpeX for simultaneous visibleand near-infrared observations and (3) CSHELL a 1-5 μmhigh-resolution spectrograph MORIS can also be used as a visiblewavelength guider for SpeX Detector upgrades have recently beenmade to SpeX We discuss new observational capabilities resultingfrom completion of a new echelle spectrograph for 1-5 μm withresolving power of 70000 with a 0375 arcsec slit This instrumentwill be commissioned starting in the spring of 2016 We also plan torestore to service our 8-25 μm camera MIRSI It will be upgradedwith a closed-cycle cooler that will eliminate the need for liquidhelium and allow continuous use of MIRSI on the telescope Thiswill enable thermal observations of NEOs on short notice We alsoplan to upgrade MIRSI to have a simultaneous visible imager forguiding and for photometry The IRTF supports remote observingfrom any site This eliminates the need for travel to the observatoryand short observing time slots can be supported We also welcomeonsite visiting astronomers In the near future we plan toimplement a low-order wave-front sensor to allow real-time focusand collimation of the telescope This will greatly improveobservational efficiency For further information on the IRTF andits instruments including visitor instruments seehttpirtfwebifahawaiiedu We gratefully acknowledge thesupport of NASA contract NNH14CK55B NASA Science MissionDirectorate

Author(s) Alan T Tokunaga S J Bus Michael SConnelley John T RaynerInstitution(s) 1 Univ of Hawaii

31221 ndash The (new) Mid-Infrared Spectrometer andImager (MIRSI) for the NASA Infrared TelescopeFacility

The Mid-Infrared Spectrometer and Imager (MIRSI) wasdeveloped at Boston University and has been in use since 2002 onthe Infrared Telescope Facility (IRTF) making observations ofasteroids planets and comets in the 2 - 25 μm wavelength rangeRecently the instrument has been unavailable due to electronicsissues and the high cost of supplying liquid helium on MaunakeaWe have begun a project to upgrade MIRSI to a cryocooler-basedsystem with new array readout electronics and a dichroic andoptical camera to simultaneously image the science field for imageacquisition and optical photometry The mechanical cryocooler willenable MIRSI to be continuously mounted on the IRTF multipleinstrument mount (MIM) along with the other facility instrumentsmaking it available to the entire community for multi-wavelengthimaging and spectral observations We will propose to use therefurbished MIRSI to measure the 10 μm flux from Near EarthObjects (NEOs) and determine their diameters and albedosthrough the use of a thermal model We plan to observe up to 750NEOs over the course of a three year survey most of whosediameters will be under 300 meters Here we present an overviewof the MIRSI upgrade and give the current status of the projectThis work is funded by the NASA Solar SystemObservationsNEOO program

Author(s) Joseph L Hora David Trilling MichaelMommert Howard A Smith Nicholas Moskovitz Alan PMarscher Alan Tokunaga Lars Bergknut Morgan Bonnet Schelte J Bus Michael Connelly John Rayner DarrylWatanabeInstitution(s) 1 Boston University 2 Harvard-SmithsonianCfA 3 Lowell Observatory 4 Northern Arizona University 5University of Hawaii

31222 ndash Solar System science with the Large SynopticSurvey TelescopeThe Large Synoptic Survey Telescope (LSST httplsstorg) will bea large-aperture wide-field ground-based telescope that willsurvey half the sky every few nights in six optical bands from 320 to1050 nm It will explore a wide range of astrophysical questionsranging from performing a census of the Solar System toexamining the nature of dark energy It is currently in constructionslated for first light in 2019 and full operations by 2022The LSST will survey over 20000 square degrees with a rapidobservational cadence to typical limiting magnitudes of r~245 ineach visit (96 square degree field of view) Automated software willlink the individual detections into orbits these orbits as well asprecisely calibrated astrometry (~50mas) and photometry(~001-002 mag) in multiple bandpasses will be available as LSSTdata products The resulting data set will have tremendouspotential for planetary astronomy multi-color catalogs ofhundreds of thousands of NEOs and Jupiter Trojans millions ofasteroids tens of thousands of TNOs as well as thousands of otherobjects such as comets and irregular satellites of the major planetsLSST catalogs will increase the sample size of objects withwell-known orbits 10-100 times for small body populationsthroughout the Solar System enabling a major increase in thecompleteness level of the inventory of most dynamical classes ofsmall bodies and generating new insights into planetary formationand evolution Precision multi-color photometry will allowdetermination of lightcurves and colors as well as spin state andshape modeling through sparse lightcurve inversion LSST iscurrently investigating survey strategies to optimize science returnacross a broad range of goals To aid in this investigation we aremaking a series of realistic simulated survey pointing historiesavailable together with a Python software package to model andevaluate survey detections for a user-defined input populationPreliminary metrics from these simulations are shown here thecommunity is invited to provide further input

Author(s) Lynne Jones Mike Brown Zeljko Ivezić MarioJurić Renu Malhotra David TrillingInstitution(s) 1 CalTech 2 Lunar and Planetary Lab 3Northern Arizona University 4 Univ of Washington

31223 ndash The Space Launch System and Missions to

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the Outer Solar SystemIntroduction Americarsquos heavy lift launch vehicle the SpaceLaunch System enables a variety of planetary science missionsThe SLS can be used for most if not all of the National ResearchCouncilrsquos Planetary Science Decadal Survey missions to the outerplanets The SLS performance enables larger payloads and fastertravel times with reduced operational complexityEuropa Clipper Our analysis shows that a launch on the SLSwould shorten the Clipper mission travel time by more than fouryears over earlier mission concept studiesJupiter Trojan Tour and Rendezvous Our mission conceptreplaces Advanced Stirling Radioisotope Generators (ASRGs) in theoriginal design with solar arrays The SLS capability offers manymore target opportunitiesComet Surface Sample Return Although in our missionconcept the SLS launches later than the NRC mission study(November 2022 instead of the original launch date of January2021) it reduces the total mission time including sample returnby two yearsSaturn Apmospheric Entry Probe Though Saturn arrivialtime remains the same in our concept as the arrival date in theNRC study (2034) launching on the SLS shortens the missiontravel time by three years with a direct ballistic trajectoryUranus Orbiter with Probes The SLS shortens travel time foran Uranus mission by four years with a Jupiter swing-by trajectoryIt removes the need for a solar electric propulsion (SEP) stage usedin the NRC mission concept studyOther SLS Science Mission Candidates Two other missionconcepts we are investigating that may be of interest to thiscommunity are the Advanced Technology Large Aperature SpaceTelescope (ATLAST) and the Interstellar Explorer also referred toas the Interstellar ProbeSummary The first launch of the SLS is scheduled for 2018followed by the first human launch in 2021 The SLS in its evolvingconfigurations will enable a broad range of exploration missionswhich will serve to recapture the enthusiasm and commitment thatpermeated the planetary exploration community during the earlyyears of robotic exploration

Author(s) Kurt K Klaus Kevin PostInstitution(s) 1 The Boeing Company

31224 ndash THEO Testing the Habitability ofEnceladusrsquos OceanSaturnrsquos moon Enceladus offers a unique opportunity in the searchfor life and habitable environments beyond Earth a key theme ofthe 2013 Decadal Survey as it informs our understanding of life andhabitability on our own planet by addressing (1) the limits of lifeunder colder fainter sun conditions (2) the importance ofhydrothermal alteration in the origin of life and (3) thedistribution of molecules in the solar system that may have servedas the precursors for life Plumes of predominately water vapor andice spew from the south pole of Enceladus Cassinirsquos data suggestthese plumes are sourced by a liquid reservoir beneath the moonrsquosicy crust that contains organics salts and water-rock interactionderivatives Thus the ingredients for life as we know itmdash liquidwater hydrocarbons and energy sourcesmdash are available inEnceladusrsquos subsurface ocean We only have to sample the plumesto investigate this hidden ocean environmentWith the help of TeamX the 2015 JPL Planetary Science SummerSchool student participants developed a proof of concept EnceladusNew Frontiers-class solar-powered orbiter The mission Testingthe Habitability of Enceladusrsquos Ocean (THEO) conducts remotesensing and in-situ analyses with the following instrument suite amass spectrometer a sub-mm radiometer-spectrometer a cameraand two magnetometers Measurements from these instrumentscan address four key questions for ascertaining Enceladean oceanhabitability within the context of the moonrsquos geological activityHow are the plumes and ocean connected Is there evidence ofbiological processes Are the abiotic conditions of the oceansuitable for habitability What mechanisms maintain the liquidstate of the ocean By taking advantage of the opportunityEnceladusrsquos plumes offer THEO represents a viable solar-poweredoption for exploring the potentially habitable ocean worlds of the

outer solar system This work was carried out at JPLCaltech undera contract with NASA

Author(s) Shannon MacKenzie Tess Caswell MatteoCrismani Kevin DeBruin Jasmeet Dhaliwal JasonHofgartner Akshata Krishnamurthy Kristen John CharityPhillips-Lander Cecilia Leung Joseph OrsquoRourke ElainePetro Samson Phan Kathryn Powell E Natasha Stavros Casey Steuer Vivian Sun Jut Wynne Charles Budney KarlMitchellInstitution(s) 1 Brown University 2 California Institute ofTechnology 3 Cornell University 4 CU Boulder 5 Jet PropulsionLaboratory California Institute of Technology 6 MassachusettsInstitute of Technology 7 NASA 8 Northern Arizona University9 Stanford University 10 University of Arizona 11 University ofCalifornia San Diego 12 University of Idaho 13 University ofMaryland 14 University of Michigan 15 University ofOklahoma 16 Washington University

31225 ndash Deliverable water from small NEOs to DRLOWe have developed a simplified mission model to estimate thequantity of deliverable water from small NEOs to distant retrogradelunar orbit (DRLO) as a function of Earth-return trip time and ΔvOur model is designed to be analytically simple computationallyefficient and close enough to optimal to provide a realistic butconservative assessment of the relevant parameters The challengestems from the fact that we are not considering a mission to aspecific known target but rather missions to the ensemble ofNEOs in a model population To further simplify the analysis wetreat Earths heliocentric orbit as circular with a semi-major axis of1 au and zero inclination

Author(s) Robert Jedicke Joel Sercel Karen Morenz Leslie S GertschInstitution(s) 1 Missouri University of Science and Technology2 TransAstra Corp 3 University of Hawaii 4 University ofToronto

31226 ndash Laboratory Spacecraft Data Processing andInstrument Autonomy AOSAT as TestbedRecent advances in small spacecraft allow for their use as orbitingmicrogravity laboratories (eg Asphaug and ThangavelauthamLPSC 2014) that will produce substantial amounts of data Powerbandwidth and processing constraints impose limitations on thenumber of operations which can be performed on this data as wellas the data volume the spacecraft can downlink We show thatinstrument autonomy and machine learning techniques canintelligently conduct data reduction and downlink queueing tomeet data storage and downlink limitations As small spacecraftlaboratory capabilities increase we must find techniques toincrease instrument autonomy and spacecraft scientific decisionmaking The Asteroid Origins Satellite (AOSAT) CubeSat centrifugewill act as a testbed for further proving these techniquesLightweight algorithms such as connected components analysiscentroid tracking K-means clustering edge detection convex hullanalysis and intelligent cropping routines can be coupled with thetradition packet compression routines to reduce data transfer perimage as well as provide a first order filtering of what data is mostrelevant to downlink This intelligent queueing provides timelierdownlink of scientifically relevant data while reducing the amountof irrelevant downlinked data Resulting algorithms allow forscientists to throttle the amount of data downlinked based oninitial experimental results The data downlink pipeline prioritizedfor scientific relevance based on incorporated scientific objectivescan continue from the spacecraft until the data is no longer fruitfulCoupled with data compression and cropping strategies at the datapacket level bandwidth reductions exceeding 40 can be achievedwhile still downlinking data deemed to be most relevant in a doubleblind study between scientist and algorithm Applications of thistechnology allow for the incorporation of instrumentation whichproduces significant data volumes on small spacecraft withoutcomparable increases to power and bandwidth budgets

1 1

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Author(s) Jack Lightholder Erik Asphaug JekanThangavelauthamInstitution(s) 1 Arizona State University

400 ndash Jovian Planet Atmospheres Stormsand Upper Atmosphere40001 ndash Spectral analysis of Uranusrsquo 2014 brightstorm with VLTSINFONIObservations by amateur observers of an extremely bright stormsystem in Uranusrsquo atmosphere in September 2014 triggered aninternational campaign to view this feature with many telescopesacross the world Near infrared observations of the storm systemwere acquired in OctoberNovember 2014 with SINFONI on ESOrsquosVery Large Telescope (VLT) in Chile SINFONI is an Integral FieldUnit spectrometer recording 64 times 64 pixel images with 2048wavelengthspixel using adaptive optics H-band (143 ndash 187 microm)image cubes were obtained at spatial resolutions of sim 01Prime perpixel The observations show that the centre of the storm featureshifts markedly with increasing altitude moving in the retrogradedirection and slightly poleward with increasing altitude A faint tailof more reflective material was also seen to the immediate south ofthe storm which again trails in the retrograde direction Theobserved spectra were analysed with the radiative transfer andretrieval code NEMESIS (Irwin et al 2008) We find that thestorm is well-modelled using either two main cloud layers of a5-layer aerosol model based on Sromovsky et al (2011) oremploying the simpler two-cloud-layer model of Tice et al (2013)The deep component appears to be caused by a brightening (ie anincrease in reflectivity) and increase in altitude of the maintropospheric cloud deck at 2 ndash 3 bars for both models while theupper component of the feature appears to be due to either athickening of the tropospheric haze of the 2-layer model or avertical extension of the upper tropospheric cloud of the 5-layermodel assumed to be composed of methane ice and based at theassumed methane condensation level at 123 bar For the 5-layermodel we also found this methane ice cloud to be responsible forthe faint lsquotailrsquo seen to the featurersquos south and the brighter polarlsquohoodrsquo seen in all observations polewards of sim 45degNDuring the twelve days between our sets of observations thehigher-altitude component of the feature was observed to havebrightened significantly and moved to even higher altitudes whilethe deeper component faded

Author(s) Patrick Gerard Joseph Irwin Leigh NFletcher Peter L Read Dane Tice Imke de Pater Glenn SOrton Nicholas A Teanby Gary R DavisInstitution(s) 1 Jet Propulsion Laboratory 2 Square KilometreArray Organisation 3 University of Bristol 4 University ofCalifornia Berkeley 5 University of Oxford

40002 ndash Bright features in Neptune on 2013-2015from ground-based observations with small (40 cm)and large telescopes (10 m)Observations of Neptune over the last few years obtained withsmall telescopes (30-50 cm) have resulted in several detections ofbright features on the planet In 2013 2014 and 2015 differentobservers have repeatedly observed features of high contrast atNeptunersquos mid-latitudes using long-pass red filters This success atobserving Neptune clouds with such small telescopes is due to thepresence of strong methane absorption bands in Neptunersquos spectraat red and near infrared wavelengths these bands provide goodcontrast for elevated cloud structures In each case theatmospheric features identified in the images survived at least a fewweeks but were essentially much more variable and apparentlyshorter-lived than the large convective system recently reported onUranus [de Pater et al 2015] The latest and brightest spot onNeptune was first detected on July 13th 2015 with the 22mtelescope at Calar Alto observatory with the PlanetCam UPVEHUinstrument The range of wavelengths covered by PlanetCam (from350 nm to the H band including narrow-band and wide-band filtersin and out of methane bands) allows the study of the vertical cloudstructure of this bright spot In particular the spot is particularly

well contrasted at the H band where it accounted to a 40 of thetotal planet brightness Observations obtained with smalltelescopes a few days later provide a good comparison that can beused to scale similar structures in 2013 and 2014 that wereobserved with 30-50 cm telescopes and the Robo-AO instrument atPalomar observatory Further high-resolution observations of the2015 event were obtained in July 25th with the NIRC2 camera inthe Keck 2 10-m telescope These images show the bright spot as acompact bright feature in H band with a longitudinal size of 8300km and a latitudinal extension of 5300 km well separated from anearby bright band The ensemble of observations locate thestructure at -41ordm latitude drifting at about +2427ordmday or -923 msconsistently with the zonal winds This work demonstratesexcellent opportunities for pro-am collaboration in the study ofNeptune and the value of nearly continuous monitoring of theplanet by a broad network of amateur collaborators

Author(s) Ricardo Hueso Marc Delcroix ChristophBaranec Agustiacuten Saacutenchez-Lavega Josep Mariacutea Goacutemez-Forrellad Jose Feacutelix Rojas Statia Luszcz-Cook Imke dePater Katherine de Kleer Franccedilois Colas Joan Guarro Peter Goczynski Paul Jones Willem Kivits Paul Maxson Michael Phillips John Sussenbach Anthony Wesley Heidi BHammel Santiago Peacuterez-Hoyos Intildeigo Mendikoa ReedRiddle Nicholas M Law Kunio SayanagiInstitution(s) 1 American Museum of National History 2Association of Universities for Research in Astronomy 3California Institute of Technology 4 Fundacioacute Observatori EsteveDuran 5 Hampton University 6 IMCCE Observatoire de Paris7 International Outer Planets Watch Planetary VirtualObservatory Laboratory 8 Socieacutete Astronomique de France 9Universidad del Paiacutes Vasco 10 University of California 11University of Hawaii at Manoa 12 University of North Carolina

40003 ndash An endurign rapidly moving storm as aguide to Saturns equatorial jet complex structureSaturn has an intense and broad eastward equatorial jet at cloudlevel whose variability and meridional and vertical structure arecomplex and actively debated Due to its 27ordm rotation axis tilt andorbital eccentricity Saturn is under a strong seasonal insolationcycle enhanced at equator by the ring shadowing periods Thesefactors make it a good natural laboratory to test models ofequatorial jet generation in giant planets We report on a brightequatorial storm at 6 degrees North latitude observed in 2015 thatmoved rapidly but steadily at a high speed of 450 ms notreported since Voyagers times (Sanchez-Lavega et al Icarus 147405-420 2000) Imaging with the Hubble Space Telescope (HST)WFC3 showed detailed storm morphology at red wavelengths (689750 and 937 nm) confirming its high speed Other equatorialclouds moved with lower velocities matching the Cassini ISS profile(Garciacutea-Melendo et al Icarus 215 62-74 2011) while the stormmatches the Voyager 1 and 2 profile We interpret this result as thesimultaneous detection of the wind profile at two separated altitudelevels within the cloud layer In addition the HST methane bandand ultraviolet images allowed retrieving winds at a third altitudelevel of motion in the haze layer above the cloud deck Combiningthe current wind data with previous dates allowed us to construct avertical ndash meridional section of the structure of Saturnrsquos equatorialjet at cloud level We discuss the implications of these results onthe long-term stability of Saturnrsquos equatorial jet

Author(s) Agustin Sanchez-Lavega Mike H Wong AmySimon Ricardo Hueso Santiago Perez-Hoyos ArrateAntuntildeano Jose Felix Rojas Teresa del Rio-Gaztelurrutia Naiara Barrado-Izagirre Itziar Garate-Lopez Enrique Garcia-Melendo Jose Francisco Sanz-Requena Josep Maria Gomez-Forrellad Imke de PaterInstitution(s) 1 Fundacioacute Observatori Esteve Duran 2 NASAGoddard Space Flight Center 3 Universidad del Pais VascoUPVEHU 4 Universidad Europea Miguel de Cervantes 5University of California

40004 ndash The Clearing of Ammonia and Deeper Cloudsin the Wake of Saturns Great Storm of 2010-2011

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Saturns Great Storm of 2010-2011 produced a planet-encirclingwake that slowly transitioned from a region that was mainly dark at5 microns in February 2011 to a region that was almost entirelybright and remarkably uniform by January 2012 (Momary andBaines 2014 AASDPS Meeting Abstracts) The uniformity andhigh emission levels suggested that the entire wake region hadbeen cleared not only of the ammonia clouds that the storm hadgenerated but also of deep aerosols that normally providesignificant blocking of the thermal emission from Saturns warmerdeep atmosphere Measurements of 22-cm emission in May 2011(Jannsen et al 2013 Icarus 226 522-535 Laraia et al 2013 Icarus226 641-654) showed that the wake region was becoming driedout with respect to ammonia vapor suggesting that a depletion ofNH clouds might be occurring Our analysis of VIMS spectra fromDecember 2012 confirmed a clearing of NH particles but showedthat two significant cloud layers remained behind about 5 opticaldepths (at 2 microns) in a 120-530 mbar layer (needed to matchlevels of reflected sunlight) and an optically thick cloud near 35bars (needed to limit 5-micron thermal emission) From spectrataken from the same latitude region upstream of the storm inFebruary 2011 we inferred a similar cloud structure with the mainexception being that the deep thermal blocking layer likelycomposed of NH SH particles was more spatially variable and at alower effective pressure (29 bars vs 35 bars) reducing 5-micronemission by a factor of 2 or more relative to the cleared region inthe wake While the storm head and early wake region displayedstrong signatures of ammonia ice these were not present prior tothe storm and disappeared completely as part of the wake clearingevent The main reason for the high 5-micron brightness of thecleared region is the removal of cloud particles in the regionbetween about 500 mbar and 35 bars Its exceptional horizontaluniformity remains to be explainedThis research was supported by a grant from NASAs CDAPSprogram

Author(s) Lawrence A Sromovsky Kevin H Baines Patrick M FryInstitution(s) 1 Univ of Wisconsin Madison

40005 ndash The Evolution of Saturnrsquos Storm-PerturbedLatitudinal Band Determined from CassiniVIMSDaytime and Nighttime SpectraSaturnrsquos Great Storm of 2010-2011 was one of the most powerfulconvective events ever witnessed as indicated for example by itsability to deliver spectrally-identifiable water ice to the top of itsconvective tower ~200 km above the water vapor condensationlevel near 20 bar (Sromovsky L A et al Icarus 226 402-4182013) and by its ability over ~ 6 months to encircle the planet withapparently anvil-like ammonia clouds sheared away from the top ofits convective tower(s) Within a half-year after the storm subsidedin mid-2011 these globe-encircling anvil-like clouds appeared tohave largely disappeared replaced by a 5-micron-bright bandencircling the planet over nearly the same latitude region the stormgenerated clouds had been indicating a dramatic decrease in theopacity of aerosols sensitive to 5-micron radiation (heat)emanating from the warm depths of the planet Here we presentquantitative results on the 5-year evolution of this storm-affected5-micron-bright region from its initial appearance associated witha large anti-cyclone that formed in the Spring of 2011 through May26-27 2015 using both daytime and nighttime CassiniVIMSspectral maps Compared to the ldquonormalrdquo unperturbed regionalcloud structure upstream of the storm as observed on Feb 24 2011we find that the initial 5-micron-bright region on May 11 2011 hadlost ~60 of its upper-cloud (100-500 mbar) opacity (i enominally 27 opacity post-storm at 2-microns vs 71 pre-storm)and that the pressure of an opaque putatively NH SHoptically-thick ldquosheetrdquo cloud dropped in altitude from a pre-stormlevel of 29 bar to the 32-bar level post-storm Subsequently overthe next 4 years the upper-cloud region recovered half of its lostopacity reaching ~56 on March 21 2014 (and nearly recovered to~ 7 in our tentative May 26-27 2015 data) corresponding to ane-folding time back to pre-storm opacity of 27 years but the lowercloud has dropped down to the 33-bar level (rising to ~ 30 bar inour tentative analysis of the May 2015 data) Throughout the

region has remained 5-micron-bright predominantly due to thedeeper warmer level of the opaque putative NH SH cloud

Author(s) KH Baines Larry A Sromovsky Patrick M Fry Thomas W Moimary Sarah Badman Robert H Brown BonnieJ Buratti Roger N Clark Philip D Nicholson Christophe SotinInstitution(s) 1 Cornell University 2 Lancaster University 3NASAJet Propulsion Laboratory 4 Planetary Science Institute 5SSECUniversity of Wisconsin-Madison 6 University of Arizona

40006 ndash Shallow Water Simulations of the Three LastSaturns Giant StormsShallow Water (SW) simulations are used to present a unifiedstudy of the polar (1960) equatorial (1990) and mid-latitude(2010) major storms in Saturn nicknamed as Great White Spots(GWS) The 2010 GWS appeared at +40 moved at -30 m s-1 wherethe Coriolis force is predominant producing an open anticyclonewith a high speed peripheral circulation and a cloud front aroundthe convective source a long-lived anticyclone and strong zonaladvection on the south part of the storm forming a turbulentregion The 1990 GWS onset took place near the equator between+12 and +5 on the broad prograde equatorial jet (450 m s-1) whereequatorial dynamics dominated producing a storm nucleus withrapid expansion to the west of a Kelvin-Helmholtz instability onthe north side of the perturbation due to advection and trappedequatorial waves which also expanded the storm to the east aroundthe equator The 1960 GWS appeared at high latitudes (+56) whereCoriolis force is predominant in a region where zonal wind velocityis 0 m s-1 SW simulations predict a strong injection of relativevorticity which may produce large anticyclones on the anticyclonicside of the zonal profile and a quick turbulent expansion on thebackground cyclonic regions at mid and high latitudes In generalsimulations indicate that negative relative vorticity injected by thestorms also defines the natural interaction with the zonal winds atlatitudes where the Coriolis force is dominant dictating its largescale dynamical behavior Numerical experiments on the 1990storm indicate that the onset of the storm can only be reproduced ifthe Voyager era background zonal flow is used which suggests thatit dominated the circulation dynamics at the stormrsquos outbreakregion at that time They also reproduce its most importantmorphological features and show the production of planetarywaves and turbulence We discuss possible mechanism for theobserved equatorial jet alterations during the storm expansion

Author(s) Enrique Garcia-Melendo Agustin Sanchez-LavegaInstitution(s) 1 Fundacio Observatori Esteve Duran 2University of the Basque Country

40007D ndash Theoretical estimation of the radiativecooling rate in the Jovian troposphereJupiter exhibits characteristic cloud activities but their physicalmechanism remains poorly understood Recently Sugiyama et al(2014) demonstrated that the Jovian cloud convection may have asignificant intermittency in the generation of cumulonimbusclouds with the typical interval length controlled by the radiativecooling rate in the upper troposphere In spite of such importanceas a controlling factor of cloud activity the tropospheric radiativecooling rate profile has never been systematically quantified for theJovian system In the Jovian troposphere condensable species(NH H S H O) and their condensates might significantlycontribute to radiative transferHere we show numerical estimates of radiative cooling rate profileunder Jovian troposphere condition by using our non-grayradiative transfer model that contains optical properties of gasspecies (H He H O CH NH H S and PH ) and cloud layersmade of H O NH SH and NH ice particles The temperatureprofile is determined by the radiative-convective equilibrium statesatisfying an observed potential temperature of Joviantroposphere The mean vertical distributions of gas and cloud aregiven on the basis of the latest hydrodynamic simulation of Joviancloud convection (Sugiyama et al 2014) and cosmochemicalconsiderationThe modeled atmosphere has the tropopause at ~038 bar level

33

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The radiative cooling rate reaches the maximum 15 x 10 KJovianday at ~05 bar level then decreases with depth and approacheszero below 5 bar level This profile is largely determined by thethermal absorption and emission due to gaseous NH and H witha slight modification by solar heating due to CH The cloud layersare found to have only a weak effect on either radiative cooling orheating because their opacities in the longwave radiation areestimated to be very small which agrees with the observed5-micron spectrum with high brightness temperatures Theuncertainty in H O abundance in deep troposphere would notaffect the radiative cooling because H O mostly condenses out inthe deep region with large optical depths for longwave radiation

Author(s) Yasuto Takahashi George L Hashimoto MasakiIshiwatari Yoshiyuki O Takahashi Ko-ichiro Sugiyama Masanori Onishi Kiyoshi KuramotoInstitution(s) 1 Hokkaido University 2 ISASJAXA 3 KobeUniversity 4 Okayama University

40008D ndash Seasonal evolution of SaturnsstratosphereThe exceptional duration of the Cassini-Huygens mission enablesunprecedented study of Saturns atmospheric dynamics andchemistry In Saturns stratosphere (from 20 hPa to 10 hPa)photochemical and radiative timescales are in the same order asSaturns revolution period (295 years) Consequently the largeseasonal insolation variations experienced by this planet areexpected to influence significantly temperatures and abundances ofphotochemical by-products in this region We investigate theseasonal evolution of Saturns stratosphere by measuringmeridional and seasonal variations (from 2005 to 2012) oftemperature and C H C H and C H abundances usingCassiniCIRS limb observations We complete this study with thedevelopment of a GCM (Global Climate Model) in order tounderstand the physical processes behind this seasonal evolutionThe analysis of the CIRS limb observations show that the lower andupper stratospheres do not exhibit the same trends in theirseasonal variations especially for temperature In the lowerstratosphere the seasonal temperature contrast is maximal (at 1hPa) and can be explained by the radiative contributions includedin our GCM In contrast upper stratospheric temperatures (at 001hPa) are constant from northern winter to spring at odds with ourGCM predictions This behavior indicates that other physicalprocesses such as gravity waves breaking may be at play At 1 hPaC H C H and C H abundances exhibit a striking seasonalstability consistently with the predictions of the photochemicalmodels of Moses and Greathouse 2005 and Hue et al 2015However the meridional distributions of these species do notfollow the predicted trends which gives insight on atmosphericdynamics We perform numerical simulations with the GCM tobetter understand dynamical phenomena in Saturns atmosphereWe investigate how the large insolation variations induced by theshadow of the rings influence temperatures and atmosphericdynamics We also study the characteristics of atmospheric wavesin the numerical simulations and compare them to existingobservations (Achterberg and Flasar 1996 Orton et al 2013)

Author(s) Melody Sylvestre Thierry Fouchet AymericSpiga Sandrine GuerletInstitution(s) 1 Laboratoire de Meacuteteacuteorologie DynamiqueUniversiteacute Pierre et Marie Curie 2 LESIA - Observatoire de Paris

401 ndash Marss Atmosphere and Surface40101 ndash Mars Science Laboratorys rover CuriosityOngoing investigations into the habitability of MarsNASArsquos Curiosity rover has the objective to determine whetherMars was habitable The roverrsquos science team has achieved that andmore including two major firsts in planetary science First GaleCrater was determined to once have an aqueous environment andable to support microbial life evidenced by conglomerates and thedetailed analyses of the drill samples [1] Second the age dating ofrock on another planet ndash radiogenic and cosmogenic noble gases in

a mudstone yielded a K-Ar age of 421 plusmn 035 Ga while 3He 21Neand 36Ar yielded surface exposure ages of 78 plusmn 30 Ma [2]suggesting the potential to find rocks whose organic content hasnot yet been destroyed by cosmic rays Indeed organic compoundshave been found in samples from the Sheepbed mudstone [3]Reports of plumes of methane in the martian atmosphere havedefied explanation to date Curiosity measured a constantbackground level of atmospheric methane with a mean value of069 plusmn 025 ppbv consistent with methane released from thedegradation of interplanetary dust and meteorites However infour consecutive measurements spanning two months the rovermeasured a ten-fold increase (72 plusmn 21 ppbv) suggesting thatmethane was actively added from an unknown source [3] Periodicmeasurements will continue perhaps revealing the possiblesources of high methane whether biological or abiologicalEnhancing our concept of Marsrsquo capability to support life theCuriosity rover has detected nitrogen-bearing compounds of110ndash300 ppm of nitrate in scooped sand and 70ndash1100 ppm ofnitrate in drilled mudstone Discovery of martian nitrogen hasimportant implications for a nitrogen cycle at some point inmartian history [4] More recent exploration has focused on theinvestigation of a mudstone-sandstone geologic contact high Siand H abundances and organics These and the latest results fromCuriosity will be discussed exploring the transition of Mars from ahabitable world to the desert planet it is today [1] Grotzinger et alScience 343 388 (2014) [2] Farley et al Science 343 389 (2014)[3] Feissinet et al JGR 120 495-514 (2015) [3] Webster et alScience 347 415-427 (2015) [4] Stern et al PNAS 1124245-4250 (2015)

Author(s) Michael Meyer Ashwin VasavadaInstitution(s) 1 JPL 2 NASA HQ

40102 ndash Liquid Water Lakes on Mars UnderPresent-Day Conditions Sustainability and Effects onthe SubsurfaceDecades of Mars exploration have produced ample evidence thataqueous environments once existed on the surface Much evidencesupports groundwater emergence as the source of liquid water onMars [1-4] However cases have also been made for rainfall [5] andsnow pack melts [6]Whatever the mechanism by which liquid water is emplaced on thesurface of Mars whether from groundwater seeps atmosphericprecipitation or some combination of sources this water wouldhave collected in local topographic lows and at least temporarilywould have created a local surface water system with dynamicthermal and hydrologic properties Understanding the physicaldetails of such aqueous systems is important for interpreting thepast and present surface environments of Mars It is also importantfor evaluating potential habitable zones on or near the surfaceIn conjunction with analysis of surface and core samples valuableinsight into likely past aqueous sites on Mars can be gainedthrough modeling their formation and evolution Toward that endwe built a 1D numerical model to follow the evolution of smallbodies of liquid water on the surface of Mars In the model liquidwater at different temperatures is supplied to the surface atdifferent rates while the system is subjected to diurnally andseasonally varying environmental conditions We recentlysimulated cases of cold (275 K) and warm (350 K) water collectingin a small depression on the floor of a mid southern latitude impactcrater When inflows create an initial pool gt 3 m deep andinfiltration can be neglected we find that the interior of the poolcan remain liquid over a full Mars year under the present cold anddry climate as an ice cover slowly thickens [7] Here we present newresults for the thermal and hydrologic evolution of surface waterand the associated subsurface region for present-day conditionswhen infiltration of surface water into the subsurface is considered[1] Pieri (1980) Science 210[2] Carr (2006) The Surface of Mars[3] Wray et al (2011) J Geophys Res 116[4] Michalski et al (2013) Nature Geosci 6[5] Craddock and Howard (2002) J Geophys Res 107[6] Clow (1987) Icarus 72[7] Goldspiel (2015) Astrobio Sci Conf Abs 7110

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113

Author(s) Jules M GoldspielInstitution(s) 1 Planetary Science Institute

40103 ndash CO -driven formation of gullies on MarsSince their discovery by the Mars Observer Camera Martian gullieshave attracted considerable attention because they resembleterrestrial debris flows formed by the action of liquid water Thisinterpretation is now questioned by the discovery of ongoing gullyformation occurring in conditions much too cold for liquid waterbut with seasonal CO frost present and defrosting However howa relatively thin seasonal dry ice cover could trigger the formationof decameter large debris flows exhibiting levees and sinuosities asif they were liquid-rich remained mysteriousWe have developed an innovative thermo-physical model of theMartian soil able to compute the seasonal evolution of a columncomposed of an underlying regolith a CO ice layer and theatmosphere above Below the surface in the CO ice layer (whenpresent) and in the regolith the model simultaneously solves theheat conduction the radiative transfer through the ice as well asthe diffusion condensation and sublimation of CO and the relatedlatent heat exchangesWe have found that during the defrosting season the pores belowthe ice layer can be filled with CO ice and subject to extremepressure variations The subsequent gas fluxes can destabilize thesoil and create gas-lubricated debris flows with the observedgeomorphological characteristics of the Martian gullies Inparticular the viscosity of such flows can be estimated to rangefrom a few tens to a few thousands of Pas similar to watertriggered debris flows and consistent with previous calculations onMartian gullies Importantly these gas fluidized debris flows canoccur below the theoretical angle of repose which has been aconcern in the understanding of gully landforms formation Wealso performed model calculations for a wide range of latitudes andslope orientations These simulations reveal that high-pressureCO gas trapping in the subsurface and the subsequent formationof ice within the regolith pores are predicted at latitudes and slopeorientations where gullies are observed and not elsewhere Inparticular the model explains why gullies are only observed on polefacing slopes between 30deg and 45deg latitude and with no orientationpreference above 45deg latitude

Author(s) Cedric Pilorget Franccedilois ForgetInstitution(s) 1 Institut dAstrophysique Spatiale 2Laboratoire de Meteorologie Dynamique

40104 ndash The Coupled Water-Dust Cycles on Mars AnInvestigation of Cloud Formation UsingMarsCAM-CARMAVariability in the present day Martian climate is dominated by theimpact of atmospheric dust On Earth mineral dust is a well knownnucleation site for high altitude cirrus clouds Similarly tenuouswater ice and carbon dioxide clouds have been observed on MarsTheir impact is expected to be large but is historically difficult tomodel accurately Here we present results from the NCARCommunity Atmosphere Model for Mars (MarsCAM) coupled witha physically based state-of-the-art cloud and dust physics packagedeveloped for Earth the Community Aerosol and Radiation Modelfor Atmospheres (CARMA) Directly modeling heterogeneousnucleation on a time varying fully interactive dust field provides afirst step to better understanding the formation distribution andcompostion of clouds on present day and early Mars

Author(s) Victoria Hartwick O Brian ToonInstitution(s) 1 University of Colorado - Boulder

40105 ndash Reduced Baroclinicity During Martian GlobalDust StormsThe eddy kinetic energy equation is applied to the Mars AnalysisCorrection Data Assimilation (MACDA) dataset during thepre-winter solstice period for the northern hemisphere of MarsTraveling waves are triggered by geopotential flux convergencegrow baroclinically and decay barotropically Higher optical depthincreases the static stability which reduces vertical and meridionalheat fluxes Traveling waves during a global dust storm year

develop a mixed baroclinicbarotropic growth phase beforedecaying barotropically Baroclinic energy conversion is reducedduring the global dust storm but eddy intensity is undiminishedInstead the frequency of storms is reduced due to a stabilizedvertical profile

Author(s) Joseph Battalio Istvan Szunyogh MarkLemmonInstitution(s) 1 Texas AampM University

40106 ndash The effect of a temperature-dependentcontact parameter on Mars cloud formationModeling the current water cycle on Mars is a complex problemthat at present remains a scientific challenge The water cycle ishighly coupled to atmospheric temperature dust surface icetemperature atmospheric transport and mixing (ie planetaryboundary layer (PBL) processes and radiation just to name a fewOne of the main features of Mars water cycle is the formation ofthe aphelion cloud belt Clouds are formed at altitude (10-40 km)within the subtropics during the aphelion season (Ls=60deg-120deg)In general the aphelion cloud belt forms at higher altitudescompared to the polar and high-latitude clouds and therefore atcolder temperatures (180 K and below) Laboratory experiments ofnucleation under cold temperatures indicate that nucleationbecomes more difficult at and below 180 K than expected This canbe modeled by using a temperature-dependent contact parameterm(T) In this study we use the NASA Ames Mars Global CirculationModel (Mars GCM) to compare the constant contact parameterwith the temperature-dependent contact parameterizationdescribed by Iraci et al (2010) The simulations demonstrate thatthe contact parameter has a significant affect on the opacity of theaphelion clouds as well as the clouds that form at the edge of theseasonal CO ice caps Both types of clouds tend to form near 180K supporting the importance of a temperature-dependent contactparameter

Author(s) Richard Atsuki Urata Jeffery Hollingsworth Melinda KahreInstitution(s) 1 Bay Area Environmental Research 2 NASAAmes Research Center

40107 ndash CRISM Limb Observations of Coincident COIce Clouds and O Emission in the Mars EquatorialMesosphereLimb observations with the CRISM visiblenear IR (04-4 μm)imaging spectrometer (Murchie et al 2009) onboard the MarsReconnaissance Orbiter have supported a broad range ofatmospheric airglow (127 μm O 145 and 29 μm OH) and aerosol(dust H O and CO ice) vertical profile retrievals Most recentlyCRISM limb observations over L =62-137deg in MY32 (Dec2013-May 2014) have obtained the first visible-to-near IRscattering spectra of CO ice clouds in the Mars equatorialmesosphere (ie 60-70 km altitudes 10S-10N over L =0-140degClancy et al 2007 Montemessin et al 2007) These spectra arehighly diagnostic of both the CO ice composition and cloudparitcle sizes (R =1-2 μm) The current report regards May 272014 (L =137deg) CRISM limb imaging observations of CO iceclouds centered near 10S75W at an altitude of 60 kmWhat is distinct about the May 2014 observation is the coincidenceof striking mesospheric O ( Δ ) 127 μm dayglow indicative ofvery low H Otemperature conditions which lead to locally intenseO enhancements (and 127 μm O emission associated with Ophotolysis) In this respect we have an unique temperatureindicator in the presence of CO ice clouds Interestingly LMDGCM photochemical simulations exhibit such localized O dayglowat the same locationseason associated with a thermal tidetemperature minimum (the current best explanation formesospheric CO ice cloud formation) We present CO cloudoptical depth and particle size determinations and discussobserved and modeled O mesospheric peak emissions in thecontext of very cold atmospheric temperatures implied by local COice formation and O emission

1

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Author(s) R T Clancy Michael Smith Franck Lefvegravere Brad Sandor Michael Wolff Tim McConnochie Kim Seelos Hari Nair Anthony Toigo Scott MurchieInstitution(s) 1 JHUAPL 2 LATMOS UPMC Univ Paris 3NASAGSFC 4 Space Science Inst 5 Univ Maryland

40108 ndash A Plume Tracing Source IdentifyingTechnique for Mars RoversWe have developed and field-tested a technique to identify andcharacterize the source of an effluent plume (biogenic orotherwise) on Mars using a slow-moving vehicle like a MarsRover The technique is based on terrestrial plume characterizationmethods (EPA Method 33a) and uses puff models of variablecomplexity to predict the plume behavior for a given source Thetechnique is developed assuming that a Mars Rover would beequipped with a high-performance eddy-sensing 3-D anemometer(eg a Martian Sonic Anemometer) as well as a fast-responsetracer molecule-specific sensor (eg a TLS methane sensor) Theplatform is assumed to move only once a day but have the abilityto observe throughout the day and night Data obtained from anyone sol while the effluent plume meanders across the rover can beused to estimate the azimuth range and strength of the source butcombining observations from multiple sols and locations is used toimprove the estimate of the souce location and strengthWe have conducted preliminary field tests using a SonicAnemometer (Gill and Campbell) and fast-response methanesensors (LICOR and Picarro) on mobile platforms using bothcontrolled and existing methane releases to prove our algorithm insimple terrain and with varying atmospheric stability We willdiscuss our results and the efficacy of our algorithm in real worldconditions

Author(s) Don Banfield Brian Lamb Chris Hovde TomFerraraInstitution(s) 1 Cornell Univ 2 GHD Inc 3 SouthwestSciences 4 Washington State University

40109 ndash Martian upper atmospheric aerosolproperties from Phobos eclipse observationSolar occultation photometry is a useful method for probing upperatmospheric aerosols using a long atmospheric path for directextinction measurements During April-June 2015 the MarsScience Laboratoryrsquos Mastcam was used for solar occultationphotometry by proxy 3 eclipse ingresses by Phobos into Marsrsquoshadow were observed as were 3 egresses from the shadow Theobservations occurred in late Southern summer at L 331-352degThe observations of the moonrsquos brightness sample the Martianatmosphere along the lines of site from the Sun to Phobos Theingresses and egresses sampled longitudes up to 1000s of km westor east of the roverrsquos position respectively sampled latitudes from30deg S to 7deg S over time and sampled local sunset or sunriserespectively Each eclipse was imaged with both Mastcam camerasM-100 with an RGB filter (638 551 and 493 nm) and M-34 withan 867-nm filter Light-curves for the eclipses were derived fromthe images and interpreted via a geometric model of the eventaccounting for the full range of lines of sight through theatmosphere The altitude of 50 extinction was found to varywithin the 40-60 km range Extinction varied with wavelengthfour events showed significantly higher extinction in the blue witha monotonic decrease with wavelength interpreted as a result of03-04 μm dust aerosols Two events (one of each type) showed nosignificant wavelength variation of extinction interpreted as aresult of large (gt1 μm) aerosols One of these probing local sunriseconditions may suggest a thin layer of CO ice cloud Future workmay allow retrieval of vertical gradients in aerosol size near themid-point of the sensitive region (ie altitudes near that of 50transmission andor path optical depth unity) andor identificationof discrete layers vs well-mixed aerosols (for instance clouds vsdust)

Author(s) Mark T LemmonInstitution(s) 1 Texas AandM University

402 ndash Asteroid Spins YORP and InteriorsThe Turning and Turning The CentreCannot Hold40201 ndash YORP Its originItrsquos all about photons and their behavior Yarkovsky (1844-1902)did not have the knowledge we have today about photons andradiation pressure Nevertheless he published a pamphlet in 1901that small rotating celestial bodies could absorb sunlight andreradiate it as heat after a delay resulting in possible orbitalchanges setting the stage for radiation effects in celestialmechanics Yarkovslyrsquos work remained obscure until Oumlpik recalledhaving read Yarkovskyrsquos pamphlet Oumlpik brought Yarkovskyrsquos ideato the attention of John A OrsquoKeefe in the late 1960s OrsquoKeefe thementor for two aspiring PhD students Paddack and Rubincamtold them about Yarkovsky In 1968 Paddack postulated that thereflection of sunlight off of small irregularly shaped celestialbodies could have a significant effect on their spin rates Hereferred to this as a windmill effect Paddack and OrsquoKeefe tested theidea of windmill shapes causing spin by dropping crushed stoneswith irregular shapes into a swimming pool and watching themtwirl Paddack then mimicked the space environment by placingwindmill-shaped artificial objects and tektites in a vacuum chamberon an almost frictionless bearing and spinning them up with astrong source of light conclusively showing the relation of shape tospin Earlier in 1954 Radzievskii wrote about the effects radiationpressure on variations in the albedo of small celestial bodies as ameans of changing their spin rates The uniform color of Paddackrsquostest bodies ruled out Radzievskiirsquos effect as the cause for theobserved spin-up The Yarkovsky effect was minimized because thetest object had a coating of vapor-deposited aluminum with a veryhigh albedo and consequently did not heat up In 2000 Rubincamapplied Paddackrsquos idea to small asteroids and called it the YORPeffect (YORP = Yarkovsky-OrsquoKeefe-Radzievskii-Paddack) to give ita catchy name and sell the idea In 2007 results were published inScience about the observed behavior of asteroid (54509) 2000 PH5stating that its spin rate changes because of the YORP effect(Lowery et al and Taylor et al) Since 2000 there have been morethan 400 papers and talks with ldquoYORPrdquo in the title or the abstract

Author(s) Stephen Paddack David P RubincamInstitution(s) 1 Goddard Space Flight Center 2 Self

40202 ndash Challenging the wall of fast rotatingasteroids ndash constraining internal cohesive strengthfor MBAs and NEAsWe report an observation of a 2 km size main belt asteroid (MBA)(60716) 2000 GD65 with a lightcurve indicating a rotation periodof 19529plusmn00002 hours ie challenging the lsquorubble pile spinbarrierrsquo This adds to a handful of MBAs recently observed by thePalomar Transient Factory (PTF) survey (Chang et al 2014 2015)with diameters between 05-15 km and lightcurves indicatingrotation periods of 12-19 hours These asteroids are relativelylarge compared to the population of small near-Earth asteroids(NEAs Dlt300 m) that can reach rotation periods as fast as 15797seconds as is the case of NEA 2014 RC (Moskovitz and MANOSteam)We apply the Holsapple (2007) model to these two distinctpopulations in order to constrain the cohesion within these objectsand to search for monolithic asteroids We use the lightcurversquosamplitude as indication of the triaxial shape ratio ab and assumebc=1 (ie agtb=c) While the density is a free parameter the givencohesion is the average of values for density ranges between 15 to25 gr cm^ which are measured density values for asteroids(Carry 2012)We find that the fast rotating MBAs must have internal cohesivestrength of at least ~25 to ~250 Pa in order to prevent disruptionagainst centrifugal acceleration Similar cohesion values have beenfound within lunar soils (100-1000 Pa Mitchell et al 1974)However since only a few MBAs rotate so quickly such internalcohesive strength might be rare within the population of km-sizeMBAs Among NEAs about 25 have minimal constrainedcohesion values similar to those found for the fast rotating MBAs

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Approximately 65 have no need for substantial cohesion valuesgt25 Pa Only ~10 of NEAs must have substantial internalcohesion of over 1000 Pa to prevent disruption however none ofthem are rotating fast enough to require a fully monolithic bodyie cohesion gt10 kPa

Author(s) David Polishook Nicholas Moskovitz Richard PBinzel Francesca E DeMeo Oded Aharonson CristinaThomas Matthew Lockhart Audrey Thirouin MichaelMommert David Trilling Brian BurtInstitution(s) 1 Lowell Observatory 2 MIT 3 NASA GoddardSpace Flight Center 4 Northern Arizona University 5 WeizmannInstitute of Science

40203 ndash Effects of Earth Encounters on theRotational Properties of Near-Earth ObjectsThe effects of Earth encounters on the physical properties ofnear-Earth objects (NEOs) have been shown to be significantfactors in their evolution Previous studies have examined theeffects of these encounters on reflectance spectra and effects suchas spin state and shape changes have been studied for specificasteroids and through simulation In this study archive data fromprevious NEO surveys were used to investigate rotationalfrequencies as a function of minimum orbit intersection distance(MOID) which we use as a proxy for Earth encounter likelihoodWhen comparing objects of similar sizes we find a highlysignificant difference in the dispersion of rotational frequency (p lt001 significant at a gt99 confidence level) between NEOpopulations that were likely to have had an Earth encounter andthose that are less likely to have had such an encounter Theencounternon-encounter distinction is found at a dividing MOIDvalue of 1 lunar distance (LD) These results were robust tochanges in the size of the moving average window as well as toremoval of the smallest objects from the encounter population andthe largest objects from the non-encounter population whichwould be most strongly affected by a known sizespin period biaswhere smaller objects tend to have shorter periods There was nostatistically significant difference in the mean rotation rates ofencounter and non-encounter objects however indicating thatencounters cause greater dispersion but do not preferentially spinobjects up or down at a detectable level Recent modeling work alsolends credibility to the idea that NEO interactions with theEarth-Moon system as a whole may be leading to the dispersiondifference boundary at 1 LD (Keane et al 2015 DPS)

Author(s) Ho Chit Siu James T Keane NicholasMoskovitz Richard P BinzelInstitution(s) 1 Lowell Observatory 2 Massachusetts Instituteof Technology 3 University of Arizona

40204 ndash Failure modes and conditions of ItokawaThe YORP effect has been found to play a crucial role in therotational evolution of small bodies Recent studies have arguedthat the YORP effect is very sensitive to the shape of an asteroid(Statler 2015 Icarus 202 502) and as the shape deforms canpossibly change (McMahon 2015 DDA meeting 30104) Suchsensitivity has been considered to affect the orbital evolution of anasteroid (Bottke et al 2015 Icarus 247 191) As a result thismysterious effect could make fast and slow rotators (personalcommunication with Bill Bottke 2015) In addition possiblecandidates of rotational disruption have also been discovered in thelast decades (eg Jewitt et al 2014 ApJ 784 L8) These studiesgave rise to the following question how does the shape of anasteroid change when subject to rotational variations from theYORP effect Better understandings of asteroid deformation andfailure at different spin periods will help us find clues of it To dothis we are surveying the failure modes and conditions of availableshape models with detailed mass information The main techniqueused is a plastic finite element model by Hirabayashi and Scheeres(2015 ApJ 798 L8) We have analyzed asteroid Itokawa which iscurrently spinning at a spin period of 121 hours Itokawarsquos failureconditions at different spin periods can be described by using theminimum cohesive strength that ensures stability of the structureThe results show that this minimum cohesive strength increases as

the spin period becomes shorter If the spin period is longer than45 hours a failure mode caused by a combination of compressionand tension occurs at cohesive strength less than 6 Pa At shorterspin periods however tension spreads out across the neck causingthe body to fail even at cohesive strength higher than it Since Hillrsquosstability condition is 52 hours once the body fails at spin periodsshorter than 45 hours it breaks into two components thateventually escape from one another In this presentation we willdiscuss the detailed failure modes and conditions of four differentshapes including Itokawa a top-like shape an elongated shape acontact binary and a strangely shaped asteroid

Author(s) Masatoshi Hirabayashi Daniel J ScheeresInstitution(s) 1 University of Colorado at Boulder

40205 ndash Asteroids With Tensile Strength The Case of2015 HM10Near-Earth asteroid 2015 HM10 was discovered on 2015 April 19with the 4-m Blanco Telescope at Cerro Tololo (MPEC 2015-H90)HM10 made a 000295 AU 114 lunar distance flyby of Earth onJuly 7 This was the asteroidrsquos closest approach to Earth until atleast 2419We observed HM10 with radar between July 5 and July 8 usingArecibo the 70 m DSS-14 and 34 m DSS-13 antennas at GoldstoneGreen Bank and elements of the Very Long Baseline Array(VLBA) Bistatic observations were crucial to obtainhigh-resolution images of HM10 due to the short round-trip traveltime of the radar signal which was as low as 295 s on July 7 Ourfinest image resolution was 375 mpixel in range obtained on July7 with the new 80 kW C-band (7190 MHz 42 cm) transmitter onDSS-13 and receiving at Green Bank with the new radar backendOptical lightcurves obtained prior to closest approach indicated thatHM10 has a spin period of ~222 minutes and an elongated shape(W Ryan pers comm) The delay-Doppler radar images confirmthe rotation period estimated from photometry and reveal thatHM10 has a long-axis extent of 80-100 m with an equatorial aspectratio of about 21 Radar speckle tracking transmitting from Areciboand receiving with the VLBA on July 6 rule out any non-principalaxis lsquowobblersquo with an amplitude greater than ~10ordmHM10rsquos rapid rotation implies significant cohesion with aminimum tensile strength of 25-150 Pa required at its center toprevent disruption assuming overall bulk density between 07 and39 g cm This is comparable to strength predictions forrubble-pile aggregates (eg Scheeres Britt Carry amp Holsapple2015 Asteroids IV in press) HM10 is not necessarily a lsquomonolithrsquoHM10rsquos shape is complex and irregular The radar images showangular features and lsquofacetsrsquo up to ~30 m across There is also acluster of radar-bright pixels that tracks with HM10rsquos rotationconsistent with a high standing feature 15-20 m across Thisfeature is similar in appearance to radar images of decameter-scaleboulders on other asteroids

Author(s) Michael W Busch Lance AM Benner Shantanu P Naidu Marina Brozovic James E Richardson Edgard G Rivera-Valentin Patrick A Taylor H Alyson Ford Frank D Ghigo Jon D Giorgini Joseph S Jao LawrenceTeitelbaumInstitution(s) 1 Arecibo Observatory 2 Jet PropulsionLaboratory California Institute of Technology 3 National RadioAstronomy Observatory 4 SETI Institute

40206 ndash Size estimate of (99942) Apophis based onradar imaging(99942) Apophis is one of the most important near-Earth asteroidsever discovered It will make a very close Earth approach on FridayApril 13 2029 when it will pass within only a few Earth radii aboveEarths surface This will be the closest approach by something thislarge currently known Apophis approached within 01 au inJanuary of 2013 and we organized an extensive radar campaign atGoldstone and Arecibo between December 2012 and March 2013Our primary objective was to obtain ranging measurements toimprove the orbit characterize its physical properties and facilitatedetection of the Yarkovsky effect leading to estimation of the massand bulk density We obtained frequency-only data and 150 m and

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75 m ranging data The signal-to-noise ratios (SNRs) were strongenough so that coarsely resolved delay-Doppler images revealedaspects of Apophisrsquo shape The visible extents varied from ~02 kmto ~04 km and the bandwidths varied from 09 Hz to14 Hz Theobject is clearly elongated which is consistent with the largelightcurve amplitude of ~09 mag reported by Behrend et al (httpobswwwunigech~behrendr099942apng) and Pravec etal (Icarus 233 48-60 2014) The radar images suggest thatApophis could be a contact binaryPravec et al have estimated the shape and spin of Apophis fromlightcurves that were collected at similar times as our radar dataThe radar data were not strong enough for 3D shape modeling butwe used the Shape software (Hudson Remote Sens Rev 8195-203 1993 and Magri et al Icarus 186 152-177 2007) to scalethe convex lightcurve-derived shape model to fit the radar data Wefind that the best χ value corresponds to the model that has043times030times026 (plusmn004 plusmn003 plusmn003) km for long intermediateand short axis and a dynamically equivalent equal volumeellipsoid of 031plusmn003 km

Author(s) Marina Brozovic Lance Benner JosephMcMichael Petr Pravec Petr Scheirich Jon Giorgini ChrisMagri Michael Busch Joseph Jao Clement Lee MichaelNolan Patrick Taylor Ellen Howell Martin SladeInstitution(s) 1 Arecibo Observatory 2 Astronomical InstituteAcademy of Sciences of the Czech Republic 3 Jet PropulsionLaboratoryCaltech 4 SETI Institute 5 University of Arizona 6University of Maine

40207 ndash Orbital and Physical Characteristics ofMeter-sized Earth ImpactorsWe have analysed the orbits and ablation characteristics in theatmosphere of more than 60 earth-impacting meteoroids of onemeter in diameter or larger Using heights at peak luminosity as aproxy for strength we find that there is roughly an order ofmagnitude spread in the apparent strength of the population ofmeter-sized impactors at the Earth The orbits and physicalstrength of these objects are consistent with the majority beingasteroidal bodies originating from the inner main asteroid belt Wefind ~10-15 of our objects have a probable cometary (Jupiter-Family comet andor Halley-type comet) origin based on orbitalcharacteristics alone Only half this number however showevidence for the expected weaker than average structure comparedto asteroidal bodies Almost all impactors show peak brightnessbetween 20-40 km altitude Several events have exceptionally high(relative to the remainder of the population) heights of peakbrightness These are physically most consistent with highmicroporosity objects though all were on asteroidal-type orbitsWe also find three events including the Oct 8 2009 airburst nearSulawesi Indonesia which display comparatively low heights ofpeak brightness consistent with strong monolithic stones or ironmeteoroids Based on orbital similarity we find a probableconnection among several NEOs in our population with the Tauridmeteoroid complex No other major meteoroid streams showlinkages with the pre-atmospheric orbits of our meter-classimpactors Our events cover almost four orders of magnitude inmass but no trend in height of peak brightness is evidentsuggesting no strong trend in strength with size for small NEOs afinding consistent with the results of Popova et al (2011)

Author(s) Peter G Brown Paul Wiegert David Clark Edward TagliaferriInstitution(s) 1 ET Space Systems 2 Univ of Western Ontario

40208 ndash Patterns of Failure in HeterogeneousSelf-gravitating AggregatesDuring the last 15 years or so the Planetary Sciences communityhas been using DEM simulation codes to study small granularNEOs In general these codes treat gravitational aggregates asconglomerates of spherical particles Lately Finite ElementMethod (FEM) codes and theoretical tools (Limit analysis)commonly used to study soil mechanics have also been employedto analyze the failure conditions and disruption patterns ofgranular asteroids as well as idealized simulation constructs One

general assumption has been that these granular systems havehomogeneous interiors In this research we change this and studythe effect of stronger and weaker interiors in their disruptionpatterns and failure mechanismsTheory and simulations have shown that homogeneous aggregatesspun at disruption rates fail initially at the centre and so it isinteresting to explore the influence of a stronger or weaker core intheir disruption mechanisms In our research we explore thefailure mechanics of spherical aggregates with an angle of frictionof 35˚ and systematically change the tensile strength and size of aspherical concentric core These aggregates are slowly spun up todisruption spin rates so that we can observe and analyze theirdisruption mechanics through our DEM code At the same time weuse Limit analysis to provide the upper and lower bounds to findthe actual conditions for failureWhat we observe is that simulations and theory point to surfaceshedding as the prevalent mechanism for aggregates with strongercores Also a core of appropriate size produces a shape profilesimilar to 1999 KW4 alpha Initial simulations of aggregates withweak cores continue to fail first a the centre but if in homogeneousaggregates there was a smooth (cohesion dependent) change fromshedding to fission here this does not happen When the size ofthe core is gt05R where R is the radius of the original bodymaterial is shed from a now oblate body For a core with a radius of05R on the other hand we observe that the break-up of the coreleads to a severe fracturing but not to fission These and otherscenarios will be explored in greater detail during the conference

Author(s) Paul Saacutenchez Daniel Scheeres MasatoshiHirabayashiInstitution(s) 1 University of Colorado at Boulder

40209 ndash Geodynamic stability of the primary in thebinary asteroid system 65803 DidymosThe moon of the near-Earth binary asteroid 65803 Didymos is thetarget of the Asteroid Impact and Deflection Assessment (AIDA)mission This mission is a joint concept between NASA and ESA toinvestigate the effectiveness of a kinetic impactor in deflecting anasteroid The mission is composed of two components theNASA-led Double Asteroid Redirect Test (DART) that will impactthe Didymos moon and the ESA-led Asteroid Impact Monitoring(AIM) mission that will characterize the Didymos system In orderto provide AIDA constraints on the physical character of the bothobjects in this binary system we undertook preliminary numericalinvestigations to evaluate the stability of the shape of the primaryusing its rapid 226 h rotation We modeled the primary as a rubblepile Each model consisted of thousands of uniform rigid spherescollapsed together under their own gravity to form a spherical pilethat was then carved to match the current radar-derived shapemodel of the primary as well as other comparable shapes (egasteroid 1999 KW4 spheres) that were scaled to match bestestimates of the size of Didymos Each model was given a startingrotation period of 6 h with the spin axis aligned to the pole At eachtimestep the spin rate was increased by a small amount so that afterabout 1 million timesteps the spin would match the observedrotation of 226 h We tested a range of bulk densities spanning thecurrent observational uncertainty (mean 24 gcc) usinggravel-like material parameters that provide significant resistanceto sliding and rolling We find that at the upper range of the densityuncertainty it is possible for Didymos to hold its shape and not losemass at its nominal rotation period without the need for cohesiveforces At lower densities or with smoother particles significantshape change occurs and mass loss is possible We conclude thatbased on the radar shape available at the time of this writingDidymos is marginally stable as a rubble pile with bulk densityclose to 3 gcc Revisions to the radar shape in process may allowfor stability at lower bulk densities without cohesion These resultssuggest that the moon of Didymos may also not be heavilyinfluenced by cohesion

Author(s) Olivier S Barnouin Clara Maurel Derek CRichardson Ronald-Louis Ballouz Stephen Schwartz PatrickMichelInstitution(s) 1 ISAE-Supaero 2 JHUAPL 3 Lagrange LabUCA Cocircte drsquoAzur Observatory CNRS 4 Univ of Maryland

2

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403 ndash Jovian Planet Interiors DeepAtmosphere and Structure40301 ndash Gravity and Zonal Flows of Giant PlanetsFrom the Euler Equation to the Thermal WindEquationThe nature of the east-west zonal flows observed on the cloud levelof the solar system giant planets remains to be determined Theupcoming gravity and magnetic field measurements to be carriedout by the Juno mission and the Cassini Grand Finale provide anopportunity to establish an observational fact about whether theseflows are shallow atmospheric dynamics or surface expression ofdeep interior dynamics It is currently debated whether the thermalwind equation (TWE) is applicable in forward calculating thegravity field associated with deep zonal flows Here we will presenta critical comparison between the Euler equation and the thermalwind equation (TWE) The TWE which is a local diagnosticrelation captures the local density variations associated with thezonal flows while neglects the global shape change and densityvariations with non-local origins Our analysis shows that theglobal corrections to the high degree gravity moments are small(less than a few tens of percent) Our analysis also shows that theapplicability of the TWE in calculating the gravity moments doesdepend crucially on retaining the non-sphericity of the backgrounddensity and gravity Only when the background non-sphericity ofthe planet is taken into account the TWE makes accurate enoughprediction (with a few tens of percent errors) for the high-degreegravity moments associated with deep zonal flows

Author(s) Hao Cao David J StevensonInstitution(s) 1 Caltech

40302 ndash The gravity signature of atmosphericdynamics on giant planets comparing the potential-theory and thermal-wind approachesThe upcoming Juno and Cassini gravity experiments of Jupiter andSaturn respectively will allow us to probe the internal dynamics ofthese planets through accurate analysis of their gravity spectra Todate two general approaches have been suggested for relating theflow velocities and gravity fields In the first potential-theory isinvoked to calculate the gravity field due to internal dynamics in anoblate spheroid planet with full differential rotation The secondapproach calculated in the reference frame of the rotating planetassumes that due to the large scale and rapid rotation of theseplanets the winds are to leading order in geostrophic balance andtherefore thermal wind balance relates the wind shear to thedensity gradients The first method allows accurate calculations ofthe gravity harmonics but can take into account only the case offull differential rotation (completely barotropic flow) while thesecond method can take into account any internal flow structurebut is limited to only calculating the dynamical contribution and tospherical symmetry This study comes to relate the two methodsboth from a theoretical perspective showing that they areanalytically identical in the barotropic limit and numericallythrough systematically comparing the model solutions of thegravity harmonics We find that despite the sphericity assumptionthe thermal wind solutions match well the potential-theorysolutions

Author(s) Joseph E Davighi Yohai Kaspi Eli Galanti William B HubbardInstitution(s) 1 University of Arizona 2 University ofCambridge 3 Weizmann Institute of Science

40303 ndash Tides in Giant PlanetsThe arrival of Juno at Jupiter in less than a year necessitatesanalysis of what we can learn from the gravitational signal due totides raised on the planet by satellites (especially Io but alsoEuropa) In the existing literature there is extensive work on statictidal theory (the response of the planet to a tidal potential whosetime dependence is ignored) and this is what is usually quotedwhen people refer to tidal Love numbers If this were correct thenthere would be almost no new information content in the

measurement of tidally induced gravity field since the perturbationis of the same kind as the response to rotation (ie themeasurement of J a well-known quantity) However tides aredynamic (that is k is frequency dependent) and so there is newinformation in the frequency dependent part There is also (highlyimportant) information in the imaginary part (more commonlyexpressed as tidal Q) but there is no prospect of direct detection ofthis by Juno since that quadrature signal is so small The differencebetween what we expect to measure and what we can alreadycalculate directly from J is easily shown to be of order the squareof tidal frequency over the lowest order normal mode frequencyand thus of order 10 However the governing equations are notsimple (not separable) because of the Coriolis force Anapproximate solution has been obtained for the n =1 polytropeshowing that the correction to k is even smaller typically a fewpercent because the tidal frequency is not very different from twicethe rotation frequency Moreover it is not highly sensitive tostructure in standard models However the deep interior of theplanet may be stably stratified because of a compositional gradientand this modifies the tidal flow amplitude changing the dynamick but not the static k This raises the exciting possibility that wecan use the determination of k to set bounds on the extent ofstatic stability if any There is also the slight possibility that thetidal frequency is coincidentally close to some resonance as wouldbe required if (as some have suggested) the tidal Q is currentlysmall (eg a few thousand or less) Predictions and detectability forJuno will be presented

Author(s) David J StevensonInstitution(s) 1 Caltech

40304 ndash Laboratory Measurements of the 5-20 cmWavelength Opacity of Ammonia and Water Vaporunder High-Temperature Conditions charactyeristicof the Deep Jovian AtmosphereIn the past decade several extensive laboratory studies have beenconducted of the microwave opacity of ammonia and water vapor inpreparation for interpretation of the precise measurements ofJovian microwave emission to be made with the Juno MicrowaveRadiometer (MWR) instrument (See eg Hanley et al (Icarus202 2009) Karpowicz and Steffes (Icarus 212 2011) Karpowiczand Steffes (Icarus 214 2011) and Devaraj et al (Icarus 2412014)) All of these works include models for the opacity of theseconstituents valid over the pressure and temperature rangesmeasured in their laboratory experiments (temperatures up to 500K and pressures up to 100 bars) However studies of the Jovianmicrowave emission indicate that significant contributions to theemission at the 24-cm and 50-cm wavelengths to be measured bythe Juno MWR will be made by layers of the atmosphere withtemperatures at or exceeding 600 K While the ammonia opacitymodels described by Hanley et al (Icarus 202 2009) and Devarajet al (Icarus 241 2014) give consistent results at temperatures upto 500 K (within 6) they diverge significantly at temperaturesand pressures exceeding 550 K and 50 bars respectively Similarlyat temperatures above 600 K the model for water vapor opacitydeveloped by Karpowicz and Steffes (Icarus 212 2011 Icarus 2142011) exhibits larger than expected microwave opacity To resolvethese ambiguities we present results of laboratory measurementsof the microwave opacity of ammonia in a hydrogenheliumatmosphere at temperatures up to 600 K and pressures up to 80Bars and that for water vapor at temperatures up to 600 K

This work was supported by the NASA Juno Mission

Author(s) Amadeo Bellotti Paul G SteffesInstitution(s) 1 Georgia Institute of Technology

40305 ndash The depths of clouds on JupiterObservational constraints on the OH ratioThe oxygen abundance in Jupiter is an important constraint onplanet formation and conditions in protoplanetary disks Oxygenin the form of water is also dynamically significant in Jupitersatmosphere as a tracer of circulation and as a carrier of latent heatWe have developed a technique to spectroscopically measure the

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depth of opaque cloud tops in Jupiters atmosphere (Bjoraker et al2015 ApJ in press arXiv150804795) We measure resolvedCH D line shapes in the 5-micron window of Jupiters spectrum todistinguish between cloud-top pressure levels of about 3 to 10 barsWe will use the retrieved cloud top pressure levels to place lowerlimits on the deep OH ratio in Jupiter based on KeckNIRSPECspectra acquired in January 2013 Since our spectra do not directlygive the temperaturepressure profile in the cloud layerconstraining the OH ratio requires independent atmosphericstructure data We will review observational and theoreticalconstraints on Jupiters thermal structure which lead touncertainty bounds on the OH ratio we derive Preliminary workto date suggests that our technique may be able to determinewhether or not the Galileo Probe Mass Spectrometer OHmeasurement can be representative of the planets bulkabundance and whether O is supersolar in Jupiter like the othervolatile elements C N and S If we can distinguish between OHlower limits of 10x and 3x solar we will be able to test thehypothesis that Jupiters volatiles must have been delivered viawater ice clathrates[This conference abstract is supported by NASA grantNNX11AM55G issued through the Outer Planets ResearchProgram and by grants NNX14AJ43G and NNX15AJ41G throughthe Planetary Astronomy and Solar System ObservationsPrograms]

Author(s) Michael H Wong Gordon L Bjoraker Imke dePater Maacuteteacute AacutedaacutemkovicsInstitution(s) 1 NASA Goddard Space Flight Center 2University of California

40306 ndash Variation in the Deep Gas Composition inHot Spots on JupiterWe used CSHELL on NASArsquos Infrared Telescope Facility andNIRSPEC on the Keck telescope in the last two years to spectrallyresolve line profiles of CH D NH PH and H O in 5-micronHot Spots on Jupiter The profile of the CH D lines at 466 micronsis very broad in both NEB and SEB Hot Spots due to collisions withup to 8 bars of H where unit optical depth occurs due to collision-induced H opacity The extreme width of these CH D featuresimplies that the Hot Spots that we observed do not have significantcloud opacity for P gt 2 bars We retrieved NH PH and gaseousH O within Hot Spots in both the NEB and SEB We had dry nightson Mauna Kea and a sufficient Doppler shift to detect H O We willcompare line wings to derive H O profiles in the 2 to 6-bar regionNEB Hot Spots are depleted in NH with respect to adjacentregions Interestingly SEB Hot Spots exhibit stronger NHabsorption than NEB Hot Spots In addition SEB Hot Spots havevery similar 5-micron spectra as neighboring longitudes in the SEBimplying similar deep gas composition The dynamical origin ofSEB Hot Spots is much less studied than that of NEB Hot Spots soour observations of gas composition in both regions may constrainmechanisms for forming Hot Spots

Author(s) Gordon Bjoraker Imke de Pater Michael HWong Mate Adamkovics Tilak Hewagama Brigette HesmanInstitution(s) 1 NASAs GSFC 2 Univ of California-Berkeley3 Univ of Maryland

40307 ndash Coupled Gas Giant Atmospheres SolarHeating vs Interior HeatingThe weather layers of Jupiter and Saturn receive both solarradiation and heat from the deep interior Currently numericalmodels fall into two broad categories deep convecting interiorsthat lack an outer solar-heated troposphere or thin shells thatrepresent only a troposphere with parameterized heating from thelower boundary Here we present results from a new coupledcirculation model that allows deep convective plumes andcolumnar structures to interact with a stable troposphere that isheated by the sun Equatorial superrotation observed on Jupiterand Saturn extends in axially-aligned columns from the deepinterior through the troposphere A tropospheric midlatitudebaroclinic zone due to solar heating competes with the outer edgesof the deep rotating columns to characterize midlatitude jet and

temperature structure We demonstrate this interplay betweensolar heating and interior heating in setting the strength and depthof the jets for a range of idealized gas giants The relative impact ofeach is modulated by the static stability of the troposphere whichacts as a proxy for water abundance We also show the impact ofaxial tilt with respect to solar radiation on asymmetries betweenthe Northern and Southern hemispheres

Author(s) Morgan E ONeill Yohai Kaspi Eli GalantiInstitution(s) 1 Weizmann Institute of Science

40308 ndash Deciphering Jupiters complex flowdynamics using the upcoming Juno gravitymeasurements and an adjoint based dynamical modelThe nature of the large scale flow on Jupiter below the cloud level isstill unknown The observed surface wind might be confined to theupper layers or be a manifestation of deep cylindrical flowMoreover it is possible that in the case where the observed wind issuperficial there exists deep flow that is completely separated fromthe surface To date all models linking the wind (via the induceddensity nomalies) to the gravity field to be measured by Junoconsider only wind flow related to the observed could level windSome assume full cylindrical flow while others allow for the wind todecay with depthHere we explore the possibility of complex wind dynamics thatinclude both the upper-layer wind and a deep flow that iscompletely detached from the flow above it The surface flow isbased on the observed cloud level flow and is set to decay withdepth The deep flow is constructed synthetically to producecylindrical structures with variable width and magnitude thusallowing for a wide range of possible setups of the unknown deepflow This flow is also set to decay when approaching the surfaceflow in coordination with the exponential decay rate The combined3D flow is then related to the density anomalies via a dynamicalmodel taking into account oblateness effects as well and theresulting density field is then used to calculate the gravitationalmoments An adjoint inverse model is constructed for thedynamical model thus allowing backward integration of thedynamical model from the expected observations of the gravitymoments to the parameters controlling the setup of the deep andsurface flows We show that the model can be used for examinationof various scenarios including cases in which the deep flow isdominating over the surface wind The novelty of our adjoint basedinversion approach is in the ability to identify complex dynamicsincluding deep cylindrical flows that have no manifestation in theobserved cloud-level wind Furthermore the flexibility of theadjoint method allows for a wide range of dynamical setups so thatwhen new observations and physical understanding will arisethese constraints could be easily implemented and used to betterdecipher Jupiter flow dynamics

Author(s) Eli Galanti Yohai KaspiInstitution(s) 1 Weizmann Institute of Science

40309 ndash Jupiterrsquos tropospheric composition andcloud structure from high-resolution ground-basedspectroscopyThe CRIRES instrument on the Very Large Telescope was used tomake high-resolution (R=100000) observations of Jupiter in the45-52 μm spectral range At these wavelengths Jupiterrsquosatmosphere is optically thin and the spectra are sensitive to the 4-8bar region This enabled us to spectrally resolve the line shapes offour minor species in Jupiterrsquos troposphere CH D GeH AsHand PH The slit was aligned north-south along Jupiterrsquos centralmeridian allowing us to search for latitudinal variability in theseline shapes The spectra were analysed using the NEMESISradiative transfer code and retrieval algorithmThe CH D line shape is narrower in the cool zones than in thewarm belts CH D is chemically stable and does not condense inJupiterrsquos atmosphere so this difference cannot be due to variationsin the CH D abundance Instead it can be modelled as variationsin the opacity of a deep cloud located at around 4 bar This deepcloud is opaque in the zones and transparent in the beltsWe also observe variability in the GeH line shape with stronger

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absorption features in the belts than in the zones As adisequilibrium species GeH is expected to vary with latitude butwe found that the variations in the line shape could be entirelyexplained by the variations in the cloud structureIn contrast there is clear evidence for spatial variability in theremaining two molecular species AsH and PH Their absorptionfeatures are weak near the equator and significantly stronger athigh latitudes A full latitudinal retrieval leads to a broadlysymmetric profile for both species with a minimum at the equatorand an enhancement towards the poles

Author(s) Rohini Sara Giles Leigh N Fletcher Patrick GJ IrwinInstitution(s) 1 Leicester University 2 Oxford University

404 ndash Extrasolar Planets Terrestrial andNeptunian Planets40401 ndash Cassini VIMS Spectra of the Earth fromSaturn Orbit an Extrasolar Planet AnalogCassini VIMS has obtained spectra of the Earth while in Saturnorbit making observations of the Saturn system when the sun wasbehind Saturn The observations made in September 15 2006 andJuly 19 2013 are visible-near-infrared spectra (035 - 51 microns)of the Earth obtained at the furthest distance from the sun to dateThe Earth was sub-pixel 00088 milliradian in 2013 and 00085milliradian in 2006 and the signal-to-noise ratio is low A VIMSpixel IFOV is 025 x 05milliradian As such these data are likely representative of the firstspectra that might be obtained of extrasolar terrestrial-like planetsWhat information can be derived from such remote observationsThe observation made in 2013 had a phase angle of 97 degrees withmultipleimage cubes providing a higher SN average The 2006 observationwas made at a phase angle of 33 degrees but is a single cube 1 pixelThe 2006 observation has Africa dominant on the disk while the2013 observation is mostly ocean with part of South America insunlight The 2013 visible data show clear signatures of Rayleighscattering but this blue coloring can be from both the atmosphereandor ocean The 2006 data show a flatter spectrum a signatureof land Both observations include the Moon in the field of viewThe 035-25 micron spectral range shows significant absorptiondue to H2O liquid + gas The thermal signature is very strong withthe highest SN of the entire spectrum The best fit preliminarytemperatures are 280 K with a small 380 K component (from theMoon) putting at least some of the planet in the goldilocks zoneThere is strong absorption by CO2 at 425 microns in both 2013and 2006 data There is possible detection of chlorophyll andoxygen emission but higher SN would be required for a positivedetection The spectral profile of the thermal emission could beused to constrain the diameter of the planet If such spectra wereobtained of an extrasolar planet we could conclude that the planethad large regions of liquid water and exposed land at temperaturesexcellent for life in a habitable zone If the chlorophyll signaturecould be confirmed it would be a positive identification of life froma remote distance

Author(s) Roger Nelson Clark Matthew M Hedman Robert H Brown Gianrico Filacchione Philip D Nicholson Jason W BarnesInstitution(s) 1 Cornel U 2 INAF 3 Planetary ScienceInstitute 4 U Arizona 5 U Idaho

40402 ndash Under an Orange Sky The ManyImplications of Organic Haze for Earthlike PlanetsGeochemical evidence suggests Archean Earth was intermittentlyenshrouded in an organic haze resulting from methane photolysisHazy exoplanets may be common and hazes can significantlyimpact the environment of habitable planets Earth is frequentlystudied as an analog for habitable exoplanets and Archean Earth isthe most alien planet we have geochemical data for We have used1D photochemical-climate and radiative transfer simulations toexamine the climate surface radiation environment and spectra of

Archean Earth with fractal hydrocarbon haze We find that hazewould have strongly impacted Earthrsquos climate lowering theplanetary surface temperature by 20-30 K However this coolingcan be countered by concentrations of greenhouses gasesconsistent with geochemical constraints For example anatmosphere with 2 CO 037 CH and a self-consistenthydrocarbon haze has a globally averaged surface temperature of274 K which GCM models have shown is consistent with a largeopen ocean fraction (Charnay et al 2013) The cooling from hazemeans that there exists a ldquohazy habitable zonerdquo closer to the starthan the traditional habitable zone boundaries Our results suggestthat the hazy habitable zone can extend to the distance of VenusAn organic haze produces strong remotely detectable spectralfeatures especially at wavelengths lt 05 μm reddening theplanetrsquos color The strong absorption of UV radiation by this hazemeans it could have provided a UV shield for the Archean Earthprior to the rise of oxygen when there was no ozone layer we showthat an organic haze can block 97 of the surface-incident UVC (λlt 028 μm) radiation compared to a haze-free planet UVCradiation directly dissociates DNA and it is blocked by ozone in themodern atmosphere Organic hazes may therefore benefit surfacebiospheres on Earth and similar exoplanets Finally assuminggeochemical constraints on the Archean atmospheric compositionwe show that abiotic levels of methane flux to the atmosphere areinsufficient to form an organic haze For Earthlike exoplanetsorganic haze may therefore be a novel type of spectral biosignature

Author(s) Giada Arney Shawn D Domagal-Goldman Victoria S Meadows Eric Wolf Edward W Schwieterman Benjamin Charnay Mark Claire Eric HebrardInstitution(s) 1 NASA Goddard Space Flight Center 2University of Colorado 3 University of St Andrews 4 Universityof Washington

40403 ndash CO Effects on Habitability of StellarExoplanet SystemsWe assess how differences in the composition of exoplanet hoststars might affect the availability of water in their systemsparticularly the role of carbon and oxygen abundances Water oneof the key chemical ingredients for habitability may be in shortsupply in carbon-rich oxygen-poor systems even if planets exist inthe lsquohabitable zonersquo For the solar system CO = 055 is particularlyimportant in determining the refractory (silicate and metal) tovolatile ice ratio expected in material condensed beyond the snowline (Gaidos E J Icarus 145 637 2000 Wong M H et al inOxygen in the Solar System GJ MacPherson Ed 2008) Ouranalysis of published compositions for a set of exoplanet host stars(Johnson T V et al ApJ 757(2) 192 2012) showed that theamount of condensed water ice in those systems might range fromas much as 50 by mass for sub-solar CO = 035 to less than a fewpercent for super-solar CO = 07 A recent analysis using similartechniques (Pekmezci G S Dottorato di Ricerca in AstronomiaUniversitagrave Degli Studi di Roma ldquoTor Vergatardquo 2014) of a muchlarger stellar composition data set for 974 FGK stars (Petigura Eand Marcy G Journal of Astrophysics 735 2011) allows us toassess the possible range of water ice abundance in thecircumstellar accretion disks of these lsquosolar-typersquo stars (of which 72were known to have one or more planets as of 2011) Stellar CO ina subset (457 stars) of this stellar database with reported C O Niand Fe abundances ranges from 03 to 14 The resulting computedwater ice fractions and refractory (silicate + metal) fractions rangefrom ~0 to 06 and 03 to 09 respectively These results haveimplications for assessing the habitability of exoplanets since theyconstrain the amount of water available beyond the snow line fordynamical delivery to inner planets depending on the host starsrsquoCO in the circumstellar nebula TVJ acknowledges governmentsupport at JPLCaltech under a contract with NASA JIL wassupported by the JWST Project through NASA OM acknowledgessupport from CNES

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Author(s) Torrence V Johnson Guumll Sevin Peckmezci Olivier Mousis Jonathan I Lunine Nikku MadhusudhanInstitution(s) 1 Aix Marseille Universiteacute CNRS LAM(Laboratoire dAstrophysique de Marseille) 2 Center forRadiophysics and Space Research 3 Institute of AstronomyUniversity of Cambridge 4 Jet Propulsion Laboratory 5Universitagrave Degli Studi di Roma ldquoTor Vergatardquo

40404 ndash Spectral identification of abiotic O buildupfrom early runaways and rarefied atmospheresThe spectral detection of oxygen (O ) in a planetary atmospherehas been considered a robust signature of life because O is highlyreactive on planets with Earth-like redox buffers and becausesignificant continuous abiotic sources were thought to beimplausible However recent work has revealed the possibility thatsignificant O may build-up in terrestrial planet atmospheresthrough (1) photochemical channels or (2) through massivehydrogen escape We focus on the latter category here Significantamounts of abiotic O could remain in the atmospheres of planetsin the habitable zones of late type stars where an early runawaygreenhouse and massive hydrogen escape during the pre-main-sequence phase could have irreversibly oxidized the crust andmantle (Luger amp Barnes 2015) Additionally it has beenhypothesized that O could accumulate in the atmospheres ofplanets with sufficiently low abundances of noncondensable gasessuch as N where water would not be cold trapped in thetroposphere leading to H-escape from UV photolysis in a wetstratosphere (Wordsworth amp Pierrehumbert 2014) Weself-consistently model the climate photochemistry and spectra ofboth rarefied and post-runaway high-O atmospheres Because anearly runaway might not have lasted long enough for the entirewater inventory to have escaped we explore both completelydesiccated scenarios and cases where a surface ocean remains Wefind ldquohabitablerdquo surface conditions for a wide variety of oxygenabundances atmospheric masses and CO mixing ratios If Obuilds up from H escape the O abundance should be very highand could be spectrally indicated by the presence of Ocollisionally-induced absorption (CIA) features We generatesynthetic direct-imaging and transit transmission spectra of theseatmospheres and calculate the strength of the UVVisible and NIRO CIA features We find that while both the UVVisible and NIRO CIA features are strong in the direct-imaging spectra of veryhigh-O atmospheres only the NIR O CIA features are significantin transmission spectra We also conclude that detection of N -NCIA in transmission or direct-imaging spectra could rule out Oorigination from H-escape from thin atmospheres

Author(s) Edward Schwieterman Victoria Meadows Shawn Domagal-Goldman Giada Arney Rodrigo Luger RoryBarnesInstitution(s) 1 NASA Goddard Space Flight Center 2University of Washington

40405 ndash Exoplanet Magma Ocean Magnetic Fieldsmay be CommonKepler data suggest that many exoplanets have low densities fortheir mass and therefore probably have hydrogen-richatmospheres For all but very thin atmospheres these have aconvective zone beneath the radiative outer region and as aconsequence have high temperatures at the assumed silicatesurface usually above the liquidus implying a magma ocean Inmany cases the resulting high internal temperatures are sufficientto allow for dynamo action in the magma There the electricalconductivities are high enough to support such a dynamo but notso high that the thermal conductivity favors conduction overconvection High conductivity is bad for a dynamo so this lowerthermal conductivity makes such magma ocean dynamospreferable to a putative iron core dynamoIn our simple models the atmospheres of exoplanets will contain aconvective zone beneath a radiative zone if sufficiently thick Wedevelop a simple model for the surface temperature of a rockyexoplanet with atmosphere-to-planet mass ratios 0001 to 10planet masses 1-10 Moplus and effective temperatures 150-1000 K Inmost models with atmosphere mass ratios greater than 01 the

rocky surface is above 1500 K above the liquidus for silicatemagma Assuming a fully molten silicate magma ocean planet ofEarthlike composition the primary mode of heat transport isconvection except at the high-temperature high atmosphere massratio end From that even with conservative estimates of theelectrical conductivity of the liquid silicate magma the nominalmagnetic Reynolds number at the surface seldom falls below 10Thus the tentative conclusion is that rocky exoplanets withsufficiently thick atmospheric envelopes to melt the surface cangenerate magnetic fields irrespective of their putative coresEstimates of the magnetic field were done following Christensenyielding surface values in the range of 01 to 05 Gauss

Author(s) Alexander Bourzutschky David StevensonInstitution(s) 1 California Instiute of Technology

40406 ndash Understanding the Early Evolution of Mdwarf Extreme Ultraviolet RadiationThe chemistry and evolution of planetary atmospheres depends onthe evolution of high-energy radiation emitted by its host starHigh levels of extreme ultraviolet (EUV) radiation can drasticallyalter the atmospheres of terrestrial planets through ionizingheating expanding chemically modifying and eroding them duringthe first few billion years of a planetary lifetime While there isevidence that stars emit their highest levels of far and nearultraviolet (FUV NUV) radiation in the earliest stages of theirevolution we are currently unable to directly measure the EUVradiation Most previous stellar atmosphere models under-predictFUV and EUV emission from M dwarfs here we present newmodels for M stars that include prescriptions for the hot lowestdensity atmospheric layers (chromosphere transition region andcorona) from which this radiation is emitted By comparing ourmodel spectra to GALEX near and far ultraviolet fluxes we are ableto predict the evolution of EUV radiation for M dwarfs from 10 Myrto a few Gyr This research is the next major step in the HAZMAT(HAbitable Zones and M dwarf Activity across Time) project toanalyze how the habitable zone evolves with the evolvingproperties of stellar and planetary atmospheres

Author(s) Sarah Peacock Travis Barman EvgenyaShkolnikInstitution(s) 1 Arizona State University 2 University ofArizona LPL

40407 ndash A Statistical Characterization of Reflectionand Refraction in the Atmospheres of sub-SaturnKepler Planet CandidatesWe present the results of our method to detect small atmosphericsignals in Keplerrsquos close-in sub-Saturn planet candidate lightcurves We detect an average secondary eclipse for groups of super-Earth Neptune-like and other sub-Saturn-sized candidates byscaling and combining photometric data of the groups ofcandidates such that the eclipses add constructively This greatlyincreases the signal-to-noise compared to combining eclipses forindividual planets We have modified our method for averagingshort cadence light curves of multiple planet candidates (2014 ApJ794 133) and have applied it to long cadence data accounting forthe broadening of the eclipse due to the 30 minute cadence Wethen use the secondary eclipse depth to determine the averagealbedo for the group In the short cadence data we found that agroup of close-in sub-Saturn candidates (1 to 6 Earth radii) wasmore reflective (geometric A ~ 022) than typical hot Jupiters(geometric A ~ 006 to 011 Demory 2014 ApJL 789 L20) Withthe larger number of candidates available in long cadence weimprove the resolution in radius and consider groups of candidateswith radii between 1 and 2 2 and 4 and 4 and 6 Earth radii We alsomodify our averaging technique to search for refracted light justbefore and after transit in the Kepler candidate light curves asmodelled by Misra and Meadows (2014 ApJL 795 L14)

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Author(s) Holly A Sheets Drake Deming Giada Arney Victoria MeadowsInstitution(s) 1 Astronomy Department University ofWashington 2 Department of Astronomy University ofMaryland

40408 ndash Mechanisms controlling the number andlatitudinal spacing of jets-streams on multiple jetplanets from terrestrial planets to gas giantsZonal jets dominate the atmospheric dynamics of a wide range ofplanetary systems as observed in all Solar System planetaryatmospheres and even observed on exoplanets Specifically whenthe ratio between the eddy length scale and the planetary scalebecomes small these planetary atmospheres develop multiple jetsIn this study we use an idealized general circulation model todemonstrate how such multiple-jets are formed and what controlstheir latitudinal width and spacing We find that for each latitudeover a wide range of parameters the jet spacing scales with theRhines scale The simulations show the presence of a criticallatitude where poleward (equatorward) of this latitude the Rhinesscale is larger (smaller) than the Rossby deformation radiusPoleward of this latitude a classic geostrophic turbulence pictureappears with a -53 spectral slope of inverse energy cascade fromthe deformation radius up to the Rhines scale A shallower slopethan the classic -3 slope of forward cascade is found from thedeformation radius down to the viscosity scale due to the broadinput of baroclinic eddy kinetic energy At these latitudeseddy-eddy interactions transfer barotropic eddy kinetic energyfrom the input scales of baroclinic eddy kinetic energy up to the jetscale and down to smaller scales We provide scaling laws for thenumber of eddy driven jets their latitudinal width and speed as afunction of a broad range of planetary parameters

Author(s) Yohai Kaspi Rei ChemkeInstitution(s) 1 Weizmann Institute of Science

40409 ndash Equilibrium and Disequilibrium Chemistryin Evolved Exoplanet AtmospheresIt has been found that sub-Neptune-sized planets although notexisting in our Solar System are ubiquitous in our interstellarneighborhood This revelation is profound because due to theirspecial sizes and proximity to their host stars Neptune- andsub-Neptune-sized exoplanets may have highly evolvedatmospheres I will discuss helium-dominated atmospheres as oneof the outcomes of extensive atmospheric evolution on warmNeptune- and sub-Neptune-sized exoplanets Due to depletedhydrogen abundance the dominant carbon and oxygen speciesmay not be methane or water on these evolved planetsEquilibrium and disequilibrium chemistry models are used tocompute the molecular compositions of the atmospheres and theirspectral features Applications to GJ 436 b and other Neptune- andsub-Neptune-sized exoplanets will be discussed As theobservations to obtain the spectra of these planets continue toflourish we will have the opportunity to study unconventionalatmospheric chemical processes and test atmosphere evolutiontheories

Author(s) Renyu HuInstitution(s) 1 Jet Propulsion Laboratory

405 ndash Galilean Satellites40501D ndash The spatial structure and temporalvariability of Ganymedersquos auroral ovals from HubbleSpace Telescope observationsWe analyze spectrally and spatially resolved images of GanymedersquosFUV-auroral ovals obtained during the past two decades byHubblersquos Space Telescope Imaging Spectrograph (HSTSTIS) Wefind both spatial inhomogeneities of the brightness-distributionon the observed disk as well as temporal variation as a function ofGanymedersquos position relative to the Jovian current sheet Thebrightness of the ovals is not equally distributed along the ovalsie the Jupiter-facing side is always brighter than the anti-Jupiter

side at least by ~60 When Ganymede moves from high elevatedmagnetic latitudes towards the center region of the Jovian currentsheet the brightness of the aurora on the leading side increases byover 30 from ~80 Rayleigh up to ~108 Rayleigh Simultaneouslyinside the current sheet center the auroral ovals are displaced by anaverage of ~6deg of planetographic latitude ie the ovals shiftfurthermore down towards the planetographic equator on theleading side and up towards the poles on the trailing side Botheffects the increase of brightness and the moving of the ovals arecorrelated to increased plasma interaction inside the current sheetGanymedersquos electron-impact-excited auroral emissions are thoughtto be driven by electron acceleration by strong field-alignedcurrents at the boundary area between open and closed magneticfield lines of Ganymedersquos mini-magnetosphere The change of theauroral morphology is a direct response to the changing plasmaenvironment ie changing ram and thermal pressures Thus theinvestigation of the aurora proves to be a suitable diagnostic tool ofthe various processes that contribute to Ganymedersquos complexplasma and magnetic field environment

Author(s) Fabrizio Musacchio Joachim Saur LorenzRoth Kurt D Retherford Melissa A McGrath Paul DFeldman Darrel F StrobelInstitution(s) 1 Department of Physics and Astronomy JohnsHopkins University 2 School of Electrical Engineering KTHRoyal Institute of Technology 3 SETI Institute 4 SouthwestResearch Institute 5 University of Cologne

40502 ndash Jupiters Satellite Europa Evidence for anExtremely Fine-Grained High Porosity SurfaceWe have measured the polarization phase curves of highlyreflective fine-grained particulate materials that simulateEuroparsquos predominately water ice regolith Our laboratorymeasurements exhibit polarization phase curves that areremarkably similar to results reported by experienced astronomers(Rosenbush et al 1997 2015) Our previous reflectance phasecurve measurements of the same materials were in agreement withthe same astronomical observers In addition we found that thesematerials exhibit an increase in circular polarization ratio withdecreasing phase angle This is consistent with coherentbackscattering (CB) of photons in the regolith (Nelson et al 20002002) Shkuratov et al (2002) report that the polarizationproperties of these particulate media are also consistent with theCB enhancement process (Shkuratov 1989 Muinonen 1990)We have reconfigured a goniometric photopolarimeter (Nelson etal 2000 2002) to undertake measurements of the polarizationphase curves of these particulate materials Our reconfigurationapplies the Helmholtz Reciprocity Principle (Hapke 2012 p264) -ie we present our samples with linearly polarized light andmeasure the intensity of the reflected component These laboratorymeasurements are physically equivalent to the astronomicalpolarization measurements We report here the polarization phasecurves of high albedo Aluminium Oxide particulates of size 01ltDlt30 microm five of which are 15 microm or smaller in diameter The phaseangle varied from 005 to 15 degrees We find for particles less thanor equal to 15 microm that the depth and position of the polarizationphase curve minimum the crossover point and the slope at thecrossover point all correlate with particle size and porosity We findzero polarization for the particle sizes greater than 2 micromOur results replicate the astronomical data and are consistent witha Europan regolith that is extremely fine-grained with remarkablyhigh porosity probably with void space exceeding 90 The EuropaClipper Mission science value would be strongly enhanced bymeasuring the polarization phase angle data of the GalileansatellitesThis work is supported by NASArsquos Cassini Saturn Orbiter mission

Author(s) Robert M Nelson Mark D Boryta Bruce WHapke Ken S Manatt Adaeze Nebedum Desiree Kroner Yuriy Shkuratov Vladimir Psarev William D SmytheInstitution(s) 1 Jet Propulsion Laboratory 2 KarazinUniversity 3 Mount San Antonio College 4 Planetary ScienceInstitute 5 University of California at Los Angeles 6 Universityof Pittsburgh

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40503 ndash Using Lava Tube Skylights To Derive LavaEruption Temperatures on IoThe eruption temperature of Iorsquos silicate lavas constrains Iorsquosinterior state and composition [1] We have examined thetheoretical thermal emission from lava tube skylights abovebasaltic and ultramafic lava channels Assuming that tube-fed lavaflows are common on Io skylights could also be commonSkylights present steady thermal emission on a scale of days tomonths We find that the thermal emission from such a targetmeasured at multiple visible and NIR wavelengths can provide ahighly accurate diagnostic of eruption temperature However thesmall size of skylights means that close flybys of Io are necessaryrequiring a dedicated Io mission [2] Observations would ideally beat night or in eclipse We have modelled the thermal emissionspectrum for different skylight sizes lava flow stream velocitiesend-member lava compositions and skylight radiation shapefactors determining the resulting flow surface cooling rates Wecalculate the resulting thermal emission spectrum as a function ofviewing geometry From the resulting 0709 μm ratios we see aclear distinction between basaltic and ultramafic compositions forskylights smaller than 20 m across even if sub-pixel Our analysiswill be further refined as accurate high-temperature short-wavelength emissivity values become available [3] This work wasperformed at the Jet Propulsion Laboratory-California Institute ofTechnology under contract to NASA We thank the NASA OPRProgram for support References [1] Keszthelyi et al (2007) Icarus192 491-502 [2] McEwen et al (2015) The Io Volcano Observer(IVO) LPSC-46 abstract 1627 [3] Ramsey and Harris (2015)IAVCEI-2015 Prague Cz Rep abstract IUGG-3519

Author(s) Ashley Gerard Davies Laszlo P Keszthelyi Alfred S McEwenInstitution(s) 1 JPL 2 University of Arizona 3 USGSAstrogeology Division

40504 ndash The Spatial Distribution of Volcanic Eventson Io in 2013-2015The spatial distribution of heat flow on Io is a key prediction of tidalheat dissipation models and therefore provides an importantconstraint for understanding Iorsquos interior However the majority ofour knowledge about eruption locations is derived from geologicalfeatures tracing long time periods (eg Hamilton et al 2013) andfrom activity during the Galileo era (eg Davies et al 2015 Veederet al 2015)We report on new results from a campaign to image Io in thenear-infrared with adaptive optics on the Keck and Gemini Ntelescopes We observed Io on 93 nights between August 2013 andJune 2015 detecting volcanic activity at dozens of hot spotlocations We present the spatial distribution of the observederuption sites during this period and compare this with thedistributions inferred from past hot spot and patera locations byprevious authors We discuss the locations of eruptions of differentmagnitudes including a preponderance of bright activity atlatitudes polewards of 45 degrees in both hemispheres and anapparent spatial clustering of activity in the months following largeeruptions Finally we address the durations of the detectederuptions as well as connecting our findings to the EXCEEDMissionrsquos observations of the Io plasma torus during the same timeperiod

Author(s) Katherine R de Kleer Imke de PaterInstitution(s) 1 UC Berkeley

40505 ndash Insights into Iorsquos volcanoes by combiningground-based and spacecraft dataActive volcanoes dominate Iorsquos surface They dominate Iorsquosinfrared flux they add to the composition of the atmosphere andare the origin of material in the Io Plasma torus Understandingwhen how and why they erupt is the key to understandingmaterial input into the Jovian system They are also key tounderstanding the dominant heating process in the solar systemtidal heating because Io is where that process has the greatest andmost obvious effectThe Galileo spacecraft obtained data from Io during periods less

than a few days on more than 30 occasions between mid 1996 andlate 2001 The New Horizons spacecraft observed Io for a 2-weekperiod in early 2007 Other spacecraft while not as useful forvolcano observations observed the Jupiter system in recentdecades The Cassini spacecraft flew by the Jupiter system in 2001and the JAXA Hisaki (SPRINT-A) spacecraft observed the Jovianmagnetosphere in 2014 The Juno spacecraft will reach Jupiter in ayear An mission specifically to Io has been submitted to theDiscovery Program and will be allowed to the New FrontiersProgram starting with call number 5NASArsquos Infrared Telescope Facility (IRTF) has been used toobserve Iorsquos volcanoes for more than two decades Data consist ofimages in 3 wavelengths (22 35 and 48 microns) with shortexposures for shift-and-add processing to increase spatialresolution In addition Jupiter occultations of Io while it is ineclipse enable the accurate determination of the intensity and 1-Dlocation of active volcanoes on the Jupiter-facing hemisphere of Iobut only in a single wavelength IRTF observations were obtainedon more than 100 nights concentrated at times when a spacecraftis also observing IoCombining data from multiple instruments and facilities hasallowed us to determine length of eruption events such as Lokiand Tvashtar as well as temperatures of the erupted lavas We willshow how IRTF and New Horizons data specifically have beencombined to yield greater information into the nature of Iorsquosvolcanism and we will discuss how ground-based observationsduring future missions can be optimized for the greatest scientificoutput

Author(s) Julie A Rathbun John R Spencer RobertHowell Rosaly LopesInstitution(s) 1 JPL 2 Southwest Research Institute 3 Univof Redlands 4 University of Wyoming

40506 ndash Sea salt irradiation experiments relevant tothe surface conditions of ocean worlds such as Europaand EnceladusWe have conducted a set of laboratory experiments to measurechanges in NaCl KCl MgCl and mixtures of these salts as afunction of exposure to the temperature pressure and radiationconditions relevant to ice covered ocean worlds in our solar systemReagent grade salts were placed onto a diffuse aluminum target atthe end of a cryostat coldfinger and loaded into an ultra-highvacuum chamber The samples were then cooled to 100 K and thechamber pumped down to ~10 Torr achieving conditionscomparable to the surface of several moons of the outer solarsystem Samples were subsequently irradiated with 10 keVelectrons at an average current of 1 microAWe examined a range of conditions for NaCl including pure saltsgrains (~300 microm diameter) salt grains with water ice deposited ontop and evaporites For the evaporites saturated salt water wasloaded onto the cryostat target the chamber closed and thenslowly pumped down to remove the water leaving behind a saltevaporate for irradiationThe electron bombardment resulted in the trapping of electrons inhalogen vacancies yielding the the F- and M- color centers Afterirraditiation we observed yellow-brown discoloration in NaCl KClwas observed to turn a distinct violet In NaCl these centers havestrong absorptions at 450 nm and 720 nm respectively providing ahighly diagnostic signature of otherwise transparent alkali halidesmaking it possible to remotely characterize and quantify thecomposition and salinity of ocean worlds

Author(s) Kevin P Hand Robert W CarlsonInstitution(s) 1 JPL

40507 ndash Linear spectral modeling of ground-basedobservations of Europa (ESOVLTSINFONI)Jupiterrsquos moon Europa may harbor a global salty subsurface liquidwater ocean (Kivelson et al 2000) and its surface should containimportant clues about its composition However debate stillpersists about the nature of the surface chemistry and the relativeroles of exogenous versus endogenous processing Recently Rothet al (2014) reported the presence of activity by the detection of

1 32

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plumes reinforcing Europa as a major target of interests ofupcoming space missions such as the ESA L-class mission JUICETo continue the investigation of the composition of the surface ofEuropa a global mapping campaign of the satellite was performedbetween October 2011 and January 2012 with the integral fieldspectrograph SINFONI on the Very Large Telescope (VLT) in ChileThe high spectral binning of this instrument (05 nm) is suitable todetect any narrow signature in the wavelength range 145-245 μmThe spatially resolved spectra we obtained over five epochs nearlycover the entire surface of Europa with a pixel scale of 125 by 25mas (~35 by 70 km on Europarsquos surface)We perform linear spectral modeling using 4 types of species water-ice (both crystalline and amorphous) sulfuric acid hydratesulfate salts and Cl-rich salts At first order spectra on the leadingside are as expected dominated by water-ice distorted andasymmetric absorption features whereas sulfuric acid hydratethought to originate from Iogenic sulfur ion bombardment isclearly predominant on the trailing side (Carlson et al 2005)Saltsare also required to fit any SINFONI spectrum with the followingnotable result when NaK-bearing chlorines instead ofMg-sulfates are used the fits are improved whatever the regionThe feature centered at ~207 microm previously associated to themagnesium sulfates (Brown et al 2013) is also observed in theSINFONI spectra and can be reproduced by some chlorine saltsGlobal abundance maps will be presented regional variations ofabundances will be discussed and the question of the endogenic orexogenic origin of salts will be addressed Finally a preliminarycomparison with similar SINFONI data of Ganymede and Callistowill be presented

Author(s) Nicolas Ligier Franccedilois Poulet John Carter Yves Langevin Christophe Dumas Florian GourgeotInstitution(s) 1 European Southern Observatory (ESO) 2Institut dAstrophysique Spatiale (IAS) 3 Observatorio Nacional(ON)

40508 ndash Thermal Coupling Between the Ocean andMantle of Europa Implications for Ocean ConvectionMagnetic induction signatures at Europa indicate the presence of asubsurface ocean beneath the cold icy crust The underlying mantleis heated by radioactive decay and tidal dissipation leading to athermal contrast sufficient to drive convection and active dynamicswithin the ocean Radiogenic heat sources may be distributeduniformly in the interior while tidal heating varies spatially with apattern that depends on whether eccentricity or obliquity tides aredominant The distribution of mantle heat flow along the seafloormay therefore be heterogeneous and impact the regional vigor ofocean convection Here we use numerical simulations of thermalconvection in a global Europa-like ocean to test the sensitivity ofocean dynamics to variations in mantle heat flow patterns Towardsthis end three end-member cases are considered an isothermalseafloor associated with dominant radiogenic heating enhancedseafloor temperatures at high latitudes associated with eccentricitytides and enhanced equatorial seafloor temperatures associatedwith obliquity tides Our analyses will focus on convective heattransfer since the heat flux pattern along the ice-ocean interfacecan directly impact the ice shell and the potential for geologicactivity within it

Author(s) Krista M Soderlund Britney E Schmidt Johannes Wicht Donald D BlankenshipInstitution(s) 1 Georgia Institute of Technology 2 Max PlanckInstitute for Solar System Research 3 University of Texas Institutefor Geophysics

406 ndash Harold Masursky Award The CSWASurvey on Workplace Climate andAnti-Harassment Policies Christina Richey(NASA HQ)40601 ndash The CSWA Survey on Workplace Climate andAnti-Harassment Policies

Workplace climate can promote or hinder scientific productivityand innovation The Committee on the Status of Women inAstronomy (CSWA) Survey on Workplace Climate sought todiscover whether scientists in the astronomical and planetaryscience communities experienced a hostile work environment Thesurvey investigated the extent to which negative experiences 1)were motivated by the targets identity (eg gender genderidentity sexual orientation ability status religion neurodiversityor race and ethnicity) and 2) affected the extent to whichrespondents felt safe in their workplaces 426 participants wererecruited for an online survey This presentation will include thepreliminary results from respondents experiences in the last fiveyears Notable conclusions include 1 Scientists in theastronomical and planetary science communities experience andwitness inappropriate language verbal harassment and physicalassault 2 Abuses that relate to gender are those that appear in thegreatest proportion in this sample 3 Inappropriate commentsharassment and assault lead to a number of scientists feelingunsafe in their workplaces and pursuing fewer scholarlyopportunities as a direct result of these experiences Thispresentation in addition to highlighting results from the recentCSWA Survey will also include a definition for harassment andhighlight the types of harassment that are frequently encounteredby scientists as well as highlight techniques for dealing withharassment both in the workplace and at conferences

Author(s) Christina RicheyInstitution(s) 1 NASA HQ

407 ndash Rosetta at Perihelion The JourneyContinues Paul Weissman (PlanetaryScience Institute)40701 ndash Rosetta at Perihelion The JourneyContinuesESArsquos Rosetta spacecraft with participation by NASA has been inorbit around the nucleus of comet 67PChuryumov-Gerasimenkofor over one year It has been a year of great discoveries andaccomplishments including the first successful spacecraft landingon the surface of a cometary nucleus (and the second and the thirdlandings) The discoveries include 1) the unusual shape of thebi-lobed nucleus 2) the substantial change of the nucleus rotationperiod (which continues to evolve) 3) the high dust-to-gas ratio 4plusmn 1 (by mass) 4) the low bulk density of the nucleus 050 gcm 5) the high deuteriumhydrogen ratio of the coma water molecules53 x 10 more than 3 times the terrestrial value 6) the highlycomplex and different terrains on the nucleus surface 7) the lack ofany intrinsic magnetic field 8) the existence of cylindrical pits inthe nucleus surface typically ~200 m in diameter and ~180 mdeep 9) the existence of ldquogoose bumprdquo terrain which may provideclues to the accretion of the comet nucleus 10) the existence ofmany similarly-sized boulders on the nucleus surface and muchmore The spacecraft and comet passed through perihelion onAugust 13 2015 which has been marked by substantialvolatile-rich outbursts from the cometary nucleus The Rosettamission has now been extended to September 2016 when thecomet and spacecraft will be approaching 4 AU outbound from theSun This talk is dedicated to the memory of Dr Claudia JAlexander US Rosetta Project Scientist who passed away in Julyof this year Her tireless efforts and tremendous enthusiasm onbehalf of Rosetta contributed greatly to the success of the mission

Author(s) Paul R Weissman Matthew Taylor Claudia JAlexanderInstitution(s) 1 European Space Agency 2 Jet PropulsionLaboratory 3 Planetary Science Institute

408 ndash 20 Years of Exoplanets From SurveysTowards Characterization Emily Rauscher(University of Michigan)

2 2 22 1 3

3 12 3

1

3

-4

3 12

124

40801 ndash 20 Years of Exoplanets From SurveysTowards CharacterizationTwenty years ago the discovery of the first planet outside of oursolar system ushered in a new subfield of exoplanet study In theyears since the number of known planets has skyrocketed into thethousands due to an ever-expanding pool of detection methodsprojects and missions and substantial improvements in techniqueThese remarkable discoveries have revealed an exoplanetpopulation that is highly diverse in many cases breakingexpectations set by the single example of our own solar system andproviding us with the opportunity to study planets under a widerange of physical conditions Equally as exciting as the increasingnumber of known exoplanets within the last dozen years we haveseen the move from exoplanet discovery to characterization weare currently able to measure atmospheric properties of many ofthe brightest exoplanets We are now in an era where we can studythe diversity of atmospheric conditions for dozens of exoplanetsincluding measurements of their temperatures albedoscompositions and in some cases even more detailed informationabout their two- or three-dimensional atmospheric structures andcirculation patterns In this talk I will review the current state oftheory and observations the lessons we have learned and thequestions and techniques that direct future work

Author(s) Emily RauscherInstitution(s) 1 University of Michigan

409 ndash Galilean Satellites40901 ndash Mutual Occultation Observations of VolcanicHot Spots on Io in 2015During spring 2015 we observed a series of mutual occultations andeclipses of Io using the SpeX instrument on the NASA InfraredTelescope Facility (IRTF) Mutual event lightcurves were obtainedon 4 Feb 18 Feb 15 Mar and 22 Mar in the Lp (38 micron)filter with observations on 11 Feb and on 8 and 10 Mar lost toweather Such lightcurves can potentially provide the highestspatial resolution observations of Ios volcanic hotspots possiblefrom ground-based observations The geometry of the recentevents was particularly favorable for studies of the Loki Pateraregion but unfortunately Loki remained relatively faint during the2015 series An eruption of Pillan was observed on 18 Feb and isdiscussed in more detail by de Pater et al (2015) at this meetingWhile the relative faintness of Loki during the recent series limitsthe value of the new observations for studying that source recentimprovements to the Galilean satellite ephemerides also allow us tosignificantly improve the analysis of previous Loki occultationsfrom 1985 1991 1997 and 2003 In that earlier work it wasnecessary to allow adjustable offsets in the relative position of thesatellites to accommodate ephemeris uncertainty That in turnlimited the accuracy with which hot regions within Loki Pateracould be fixed and limited the ability to test different models forPatera activity Initial analysis of the most recent event seriesindicates that such arbitrary adjustments are no longer necessaryWe will present the occultation lightcurves for the most recentseries and the constraints on the location of Loki activity providedby those observations and from earlier occultation series

Author(s) Robert R Howell John R Spencer Julie ARathbun Jay D GoguenInstitution(s) 1 JPL 2 Planetary Science Institute 3 SwRI 4Univ of Wyoming

40902 ndash Large Binocular Telescope Observations ofEuropa Occulting Ios Volcanoes at 48 μmOn 8 March 2015 Europa passed nearly centrally in front of Io TheLarge Binocular Telescope observed this event in dual-apertureAO-corrected Fizeau interferometric imaging mode using themid-infrared imager LMIRcam operating behind the LargeBinocular Telescope Interferometer (LBTI) at a broadbandwavelength of 48 μm (M-band) Occultation light curves generatedfrom frames recorded every 123 milliseconds show that both Lokiand PelePillan were well resolved Europas center shifted by 2

kilometers relative to Io from frame-to-frame The derived lightcurve for Loki is consistent with the double-lobed structurereported by Conrad et al (2015) using direct interferometricimaging with LBTI

Author(s) Michael F Skrutskie Albert Conrad AaronResnick Jarron Leisenring Phil Hinz Imke de Pater Katherine de Kleer John Spencer Andrew Skemer Charles EWoodward Ashley Gerard Davies Denis DefreacutereInstitution(s) 1 Amherst College 2 Large Binocular TelescopeObservatory 3 NASAJPL 4 Southwest Research Institute 5Univ of Minnesota 6 Univ Of Virginia 7 University of Arizona8 University of California Berkeley

40904 ndash Search for Trace Species at EuropaUnderstanding the present surface composition of Europa providescritical information about its potential habitability From Earth wecurrently have very few tools at our disposal to measure Europarsquoscomposition Two notable exceptions are Keck NIR spectroscopy(cf Brown and Hand 2013) and Hubble Space Telescope UVspectroscopy (cf Cunningham et al 2015) In March 2015 weobtained 5 orbits of deep UV spectroscopy of Europa using theCosmic Origins Spectrograph covering wavelength range1170ndash1760 Aring The purpose of the observations was to detect tracespecies in Europarsquos exosphere which is generated by chargedparticle sputtering of Europarsquos water ice surface The compositionof the exosphere therefore provides an indirect measurement ofsurface composition Furthermore if active plumes are present thecomposition of the exosphere may also reflect the composition ofEuroparsquos subsurface water reservoir Of particular interest in theobserved wavelength range are multiplets of atomic chlorinebecause chlorine is predicted to be a major constituent of Europarsquosocean (Kargel et al 2000) and Na and K chlorides are expected tobe major constituents of the icy shell (Zolotov and Shock 2001Zolotov and Kargel 2009) The present situation at Europa isanalogous to that at Io in the late 1990s when chlorine ions werefirst detected in the plasma near Io (Kuppers and Schneider 2000)motivating searches for atomic chlorine and chlorine-bearingspecies that were subsequently detected in Iorsquos atmosphere(Lellouch et al 2003 Feaga et al 2004) Galileo plasmameasurements have detected chlorine ions near Europa (Volwerket al 2001) which has motivated the present search for chlorine inEuroparsquos exosphere We will present the new COS spectra ofEuropa and discuss the implications of the trace species that havebeen detected in these data

Author(s) Melissa McGrath William Sparks JohnSpencerInstitution(s) 1 SETI Institute 2 STScI 3 SWRI

40905 ndashThe distinct spectrum of large-scale chaos on Europafrom 1-4 micronWe present new spatially-resolved reflectance spectra of thesurface of Europa obtained with Keck NIRSPEC and adaptiveoptics These include the first spatially-resolved high-quality 3-4micron spectra on Europa In recent work (Fischer et al 2015 inreview) we show that Europas surface consists of three majorcompositional units at the ~100 km scale one of which isgeographically associated with large-scale chaos and thereforeendogenous processes We focus on this region we will present thefirst moderate-resolution spectrum of large-scale chaos from14-25 and 31-40 micron We will also present cryogeniclaboratory spectra of candidate materials from 1-4 micron anddiscuss the implications for identifying Europas nativecomposition

Author(s) Patrick D Fischer Michael E Brown Kevin PHandInstitution(s) 1 Caltech 2 JPL

40906 ndash Time Evolution of Iorsquos volcanoes Pele andPillan from 1996 ndash 2015 as derived from Galileo NIMSKeck Gemini IRTF and LBTI observations

1

4 32 1

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We present highlights of our observations of Pele and Pillan on Ioand a multi-decade timeline of thermal emission intensities in bothregions Io was regularly observed by Galileo NIMS during1996-2001 Since 2001 the satellite has been imaged semi-regularlywith NIRC2 coupled to an adaptive optics system on the 10-mKeck telescope In 1997 Galileo NIMS observed a large and highly-variable eruption close to Pillan Mons this eruption lasted severalmonths [1] Since that time no eruptions had been seen (but timecoverage was scarce) until our Keck images on 14 August 2007revealed an active and highly-energetic eruption at a location closeto that of the 1997 eruptions A one-temperature blackbody fit tothe data revealed a (blackbody) temperature of 840 plusmn 40 K over anarea of 17 km with a total power output of ~500 GW UsingDaviesrsquo (1996) Io Flow Model [2] we find that the oldest lavapresent is less than 1-2 hours old having cooled down from theeruption temperature of gt1400 K to ~710 K This young hot lavasuggests that an episode of lava fountaining was underway Since2007 several eruptions have been seen in the Pillan region The 18February 2015 eruption was discovered during a mutualoccultation event with the NASA IRTF This event was(serendipitously) subsequently imaged with the Large BinocularTelescope Interferometer (LBTI) on 8 March 2015 during a mutualevent occultation and again with the IRTF on 15 March The sitewas imaged with the Keck and Gemini-N telescopes between 27March and May 5 during which time the intensity graduallydecreased Interestingly the precise location of the eruption hadshifted to the north-west from Pillan Patera where the initial (18Feb) eruption had taken place In contrast to the episodicity ofPillan Pele has been remarkably consistent in its thermal emissionduring the Galileo era [1] through February 2002 when ablackbody temperature of 940 plusmn 40 K and an area of 65 km wasmeasured Since that time however the radiant flux from this largeoverturning lava lake has gradually subsided over the next decadeby a factor of ~4 [1] Davies et al (2001) JGR 106 33079-33103[2] Davies (1996) Icarus 124 45-61

Author(s) Imke de PaterInstitution(s) 1 UC Berkeley

410 ndash Enceladus41001 ndash Resolving Enceladus thermal emission at the10s of meters scale along Baghdad Sulcus usingCassini CIRSOn 14 April 2012 Cassini executed one of its closest flyby to theSouth Pole of Enceladus with the primary goal to study the moonrsquosgravity During this flyby the Composite InfraRed Spectrometer(CIRS) was orientated such that its three focal planes were draggedacross Baghdad sulcus The instrument was specifically configuredto record interferograms with 52 seconds duration CIRS focalplane 1 (17 to 1000 microm) single circular detector provided a spatialresolution of about 300 meters CIRS focal plane 3 and 4 (9 to 17microm and 7 to 9 microm) are 2 1x10 detectors arrays Both arrays wereused in pair mode leading to 5 elements per focal plane and aresolution of about 43 meters across trackThe ground-track speed was so fast during this observation thatthis was enough time to observe the entire South Polar Region in asingle integration The thermal sources were passed over so rapidlythat it is not possible to reconstruct a spectrum from the resultinginterferogram instead features were created in the interferogramwhenever the scene temperature changed The signature of thesefeatures was also altered by bit trimming and band-pass filterconvolution To enable interpretation of the interferograms wedeveloped an innovative new approach that included thedevelopment of new instrument models modification of the flightsoftware and multiple in flight validation experiments Ourpreliminary results show temperature variability of the tiger stripesat 10s meters scale along track providing a constraint on thedistribution and temperature profile of Enceladusrsquo endogenicsourcesA similar methodology will be used for the penultimate targetedEnceladus flyby in Oct 28 2015 and we aim to also present ourpreliminary analysis of the results from this encounter

Author(s) Nicolas Gorius Carly Howett John Spencer Shane Albright Don Jennings Terry Hurford Paul Romani Marcia Segura Anne VerbiscerInstitution(s) 1 Catholic University of America 2 GoddardSpace Flight Center 3 Southwest Research Institute 4 System andSoftware Design 5 University of Maryland 6 University ofVirginia

41002 ndash Drawing the Curtain on EnceladusSouth-Polar EruptionsFor a comprehensive description of Enceladus south-polareruptions observed at high resolution they must be represented asbroad curtains rather than discrete jets Meanders in the fracturesfrom which the curtains of material erupt give rise to opticalillusions that look like discrete jets even along fractures with nolocal variations in eruptive activity implying that many featurespreviously identified as jets are in fact phantoms By comparingCassini images with model curtain eruptions we are able to obtainmaps of eruptive activity that are not biased by the presence ofthose phantom jets The average of our activity maps over all timesagrees well with thermal maps produced by Cassini CIRS We canbest explain the observed curtains by assuming spreading angleswith altitude of up to 14deg and zenith angles of up to 8deg for curtainsobserved in geometries that are sensitive to those quantities

Author(s) Joseph N Spitale Terry A Hurford Alyssa RRhoden Emily E Berkson Symeon S PlattsInstitution(s) 1 Arizona State University 2 NASA GoddardSpace Flight Center 3 Planetary Science Institute 4 RochesterInstitute of Technology 5 University of Arizona

41003 ndash Venting of CO at Enceladusrsquo SurfaceEnceladus has CO surface deposits in its South Polar Region thathave been recently mapped by J-P Combe et al (2015 AGU FallMeeting) Assuming that these are CO frost we show how theycan be formed We use an ocean-water circulation model [1] thatspecifies pressure gradients that drive water to the surface from arelatively gas-rich subsurface ocean We now examine themovement of CO to the surface formation of shallow CO gaspockets in the ice and the venting of CO when at least some ofthe gas freezes to form frost If the local heat flow is known (cf[2]) then the depths of the corresponding gas pockets can becalculated References [1] Matson et al (2012) Icarus 221 53-62[2] Howett et al (2011) J Geophys Res 116 E03003Acknowledgements AGD thanks the NASA OPR Program forsupport

Author(s) Dennis L Matson Ashley G Davies Torrence VJohnson Jean-Philippe Combe Tom B McCord JaniRadebaughInstitution(s) 1 Bear Fight Institute 2 Brigham YoungUniversity 3 Jet Propulsion Laboratory-California Institute ofTechnology

41004 ndash Inside Enceladusrsquo plumes the view fromCassinirsquos mass spectrometerBetween early 2008 and late 2012 the Ion and Neutral MassSpectrometer (INMS) on Cassini measured particles deep insidethe plumes of Enceladus seven times from varying altitudes andlocations From these measurements and the models that usethem we have extracted information that can be used to constrainthe physical processes that create the plumes and govern theirsourceNeutral densities are high only when INMS is within view of thetiger stripes Inside the plumes INMS measures spatial variationsthat are consistent with Mach-4 jets superimposed on more-diffusevapor INMS measured vapor velocity directly during a portion ofone encounter finding a Mach-4 distribution centered on 12 kmsModeling of vapor sources distributed along the tiger stripes showthey contribute 20 to 75 of the total density depending on theencounter and assumptions on the discrete sources Model-fittedvelocities range from 500 to 1300 ms The INMS data also show3x variations in total density that are consistent with theorbit-phase variations detected in visual and IR remote

2

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1 3 34 2 2 2

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2

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2

2 22

1 31 3 3

2

126

observations of dust plumes Only H O ions are observed clearlyinside the plumesAn ice grain entering INMS increases the counts for onemeasurement These spikes are the largest source of uncertainty(40) in vapor measurements but also provide independentmeasurements of ice grains The frequency of these ice grainsmatches the Cosmic Dust Analyzer counts for grains larger than 02μm Their orbit-phase variability as seen by INMS is also consistentwith VIMS dataWater vapor comprises at least 90 of the plumes with CO NH and CH positively identified and less than 1 each H is likely5-10 but its abundance is uncertain due to fractionation of H Oin the instrument A species (CO or N ) with a mass of 28 u is asabundant as CO The C group totals lt 05 and the C group lt001 The high-velocity encounters show carbon fractions oforganic molecules with masses gt 100 u During individualencounters CO and the 28-u species show differences that aredue at least in part to mass-dependent thermal spreading inhigh-velocity jets There has been no significant variation in totalcomposition between encounters

Author(s) Mark E Perry Dana M Hurley Ben D Teolis JHunter Waite Brian A Magee H Todd Smith ValeriyTenishev Joe H Westlake Ralph L McNuttInstitution(s) 1 Johns Hopkins Applied Physics Lab 2Southwest Research Institute 3 University of Michigan

41005 ndash Modeling of the Enceladus water vapor jetsfor interpreting UVIS star and solar occultationobservationsOne of the most spectacular discoveries of the Cassini mission isjets emitting from the southern pole of Saturnrsquos moon EnceladusThe composition of the jets is water vapor and salty ice grains withtraces of organic compounds Jets merging into a wide plume at adistance are observed by multiple instruments on Cassini Recentobservations of the visible dust plume by the Cassini ImagingScience Subsystem (ISS) identified as many as 98 jet sourceslocated along ldquotiger stripesrdquo [Porco et al 2014] There is a recentcontroversy on the question if some of these jets are ldquoopticalillusionrdquo caused by geometrical overlap of continuous sourceeruptions along the ldquotiger stripesrdquo in the field of view of ISS [Spitaleet al 2015] The Cassinirsquos Ultraviolet Imaging Spectrograph (UVIS)observed occultations of several stars and the Sun by the watervapor plume of Enceladus During the solar occultation separatecollimated gas jets were detected inside the background plume[Hansen et al 2006 and 2011] These observations directly providedata about water vapor column densities along the line of sight ofthe UVIS instrument and could help distinguish between thepresence of only localized or also continuous sources We useMonte Carlo simulations and Direct Simulation Monte Carlo(DSMC) to model the plume of Enceladus with multiple (orcontinuous) jet sources The models account for molecularcollisions gravitational and Coriolis forces The models result inthe 3-D distribution of water vapor density and surface depositionpatterns Comparison between the simulation results and columndensities derived from UVIS observations provide constraints onthe physical characteristics of the plume and jets The specificgeometry of the UVIS observations helps to estimate theproduction rates and velocity distribution of the water moleculesemitted by the individual jetsHansen C J et al Science 3111422-1425 (2006) Hansen C J etal GRL 38L11202 (2011) Porco CC et al Astron J 148 45(2014) Spitale JN et al Nature 521 57-60 (2015)

Author(s) Ganna Portyankina Larry W Esposito Klaus-Michael Aye Candice J HansenInstitution(s) 1 Laboratory for Atmospheric and Space PhysicsUniversity of Colorado 2 Planetary Science Institute

41006 ndash Modeling of the spatial profile of neutrals inthe plume of Enceladus observed by Cassini INMSMonte Carlo modeling of the vapor erupting from EnceladusrsquoSouth polar region is presented to demonstrate the influence ofphysical characteristics of the emitted vapor on the distribution of

particles at altitude The modeled sources include both localizedjets and eruptions distributed along the surface features calledldquotiger stripesrdquo The modeling reveals that density enhancements ataltitude can be displaced from the source location Thedisplacement can be produced by the angle of emission Howeverin some cases it is caused by superposition of material fromadjacent sources Assuming different molecules are emitted at thesame bulk velocity and the same temperature differences in theamount of spreading for the different species emerges owing to thedependence of thermal velocity on mass The altitude of thesuperposition is mass dependent and contributes to differencesobserved in the mass 28 and mass 44 channels of the Cassini INMSduring Enceladus encountersWe present comparisons of INMS data with the model for fourCassini Enceladus flybys INMS data are modeled using only thetiger stripe sources to reproduce the broad structure of the plumeThe difference between the data and the model is attributed to thepresence of stronger more-localized sources which are identifiedby their excess In particular an additional source is required formass 44 u on the Saturn-facing hemisphere of Baghdad Sulcus Itis apparent in 3 parallel Cassini flybys A relative decrease in thesource rate is observed for mass 28 u for E14 The lack ofsmall-scale spatial structure of high-density regions in the 28 uINMS observations compared to the more collimated structure ofthe 44 u INMS observations is consistent with increased thermalspreading for low-mass constituents of the plume This indicatesthat even less spatial structure should be expected for thedominant species in the plume--water

Author(s) Dana Hurley Mark Perry Hunter WaiteInstitution(s) 1 JHUAPL 2 SwRI

411 ndash Icy Satellites41101 ndash Searching for Thermal Anomalies on IcySatellites Step 1- Validation of the Three DimensionalVolatile-Transport (VT3D)In the last few decades thermal data from the Galileo and Cassinispacecraft have detected various anomalies on Jovian andSaturnian satellites including the thermally anomalous ldquoPacManrdquoregions on Mimas and Tethys and the Pwyll anomaly on Europa(Howett et al 2011 Howett et al 2012 Spencer et al 1999) Yetthe peculiarities of some of these anomalies like the weakdetection of the ldquoPacManrdquo anomalies on Rhea and Dione and thelow thermal inertia values of the widespread anomalies onequatorial Europa are subjects for on-going research (Howett et al2014 Rathbun et al 2010) Further analysis and review of all thedata both Galileo and Cassini took of these worlds will provideinformation of the thermal inertia and albedos of their surfacesperhaps highlighting potential targets of interest for future Jovianand Saturnian system missions Many previous works have used athermophysical model for airless planets developed by Spencer(1990) However the Three Dimensional Volatile-Transport(VT3D) model proposed by Young (2012) is able to predict surfacetemperatures in significantly faster computation timeincorporating seasonal and diurnal insolation variations This workis the first step in an ongoing investigation which will use VT3Drsquoscapabilities to reanalyze Galileo and Cassini data VT3D which hasalready been used to analyze volatile transport on Pluto isvalidated by comparing its results to that of the Spencer thermalmodel We will also present our initial results using VT3D toreanalyze the thermophysical properties of the PacMan anomalyprevious discovered on Mimas by Howett et al (2011) usingtemperature constraints of diurnal data from CassiniCIRS VT3Dis expected to be an efficient tool in identifying new thermalanomalies in future Saturnian and Jovian missionsBibliographyCJA Howett et al (2011) Icarus 216 221CJA Howett et al (2012) Icarus 221 1084CJA Howett et al (2014) Icarus 241 239JA Rathbun et al (2010) Icarus 210 763J R Spencer (1990) Icarus 83 27J R Spencer et al (1999) Science 284 1514L A Young (2012) Icarus 221 80

3 +

2 34 2

22

2 2 3

2

1 1 22 2 1

3 1 1

1 11 2

1 1 2

127

Author(s) Gary G Simmons Carly JA Howett Leslie AYoung John R SpencerInstitution(s) 1 Southwest Research Institute 2 University ofColorado-Boulder

41102 ndash Dark material on the classical Uraniansatellites What is it and where did it come fromDuring Voyager 2rsquos flyby of Uranus its Imaging Science Subsystem(ISS) camera captured tantalizing images of the icy gray-tonedsurfaces of the classical Uranian satellites Additionallyground-based near-infrared (NIR) observations of these moonshave detected a mixture of H O ice and a low albedo andpotentially carbonaceous constituent on their surfaces Analysis ofISS color maps demonstrated that the leading hemispheres of thesemoons are spectrally redder than their trailing hemispheres andboth the degree of reddening and the correlation between lowalbedo and spectrally red regions increases with distance fromUranus However ISS almost exclusively observed the southernhemispheres of these moons (subsolar point ~81ordm S) and we havecollected new observations of their northern hemispheres (currentsubsolar point ~29ordm N) By characterizing the distribution of thedark material we will be able to constrain the primary productionmechanism for this low albedo constituent Our preferredhypothesis is that the dark material represents accumulatedintraplanetary dust that originated on Uranusrsquo retrograde irregularsatellitesTo characterize the distribution of the spectrally red low albedomaterial on these moons we are measuring their spectral slopesusing visible wavelength (VIS) spectra and photometry gatheredover similar wavelengths to those sensed by ISS (~04 ndash 06 microm)Additionally we have collected NIR spectra of these satellites inorder to characterize the relative strengths of 152 and 202 micromH O ice bands which are modified by the presence of low albedocontaminants Our results indicate that the 152 and 202 microm H Obands are stronger on the leading hemispheres of these moonsand the hemispherical asymmetry in H O band strengthsdecreases with distance from Uranus Spectral modeling of theseNIR spectra will help discern between contaminant mixing andgrain size effects on the relative strength of the H O bands We willpresent our interpretation of the H O band strength results andour ongoing analysis of VIS spectral slopes for the classical Uraniansatellites

Author(s) Richard J Cartwright Joshua P Emery Michael P Lucas Noemi Pinilla-Alonso David E Trilling AndyS RivkinInstitution(s) 1 John Hopkins University Applied PhysicsLaboratory 2 Northern Arizona University 3 University ofTennessee

41103 ndash Structural diversity of the 3-micronabsorption band in Enceladusrsquo plume from CassiniVIMS Insights into subsurface environmentalconditionsWater ice particles in Enceladusrsquo plume display their diagnostic3-micron absorption band in Cassini VIMS data These nearinfrared measurements of the plume also exhibit noticeablevariations in the character of this band Mie theory calculationsreveal that the shape and location of the 3-micron band arecontrolled by a number of environmental and structuralparameters Hence this band provides important insights into theproperties of the water ice grains and about the subsurfaceenvironmental conditions under which they formed For examplethe position of the 3-micron absorption band minimum can beused to distinguish between crystalline and amorphous forms ofwater ice and to constrain the formation temperature of the icegrains VIMS data indicates that the water ice grains in the plumeare dominantly crystalline which could indicate formationtemperatures above 113 K [eg 1 2] However there are slight (butobservable) variations in the band minimum position and bandshape that may hint at the possibility of varying abundance ofamorphous ice particles within the plume The modeling resultsfurther indicate that there are systematic shifts in band minimumposition with temperature for any given form of ice but the

crystalline and amorphous forms of water ice are stilldistinguishable at VIMS spectral resolution Analysis of theeruptions from individual source fissures (tiger stripes) usingselected VIMS observations reveal differences in the 3-micronband shape that may reflect differences in the size distributions ofthe water ice particles along individual fissures Mie theory modelssuggest that big ice particles (gt3 micron) may be an importantcomponent of the plume[1] Kouchi A T Yamamoto T Kozasa T Kuroda and J MGreenberg (1994) AampA 290 1009-1018 [2] Mastrapa R M E WM Grundy and M S Gudipati (2013) in M S Gudipati and JCastillo-Rogez (Eds) The Science of Solar System Ices pp 371

Author(s) Deepak Dhingra Matthew M Hedman Roger NClarkInstitution(s) 1 Planetary Science Institute 2 University ofIdaho

41104 ndash Deriving the Structure and Composition ofEnceladusrsquo Plume from Cassini UVIS ObservationsCassinirsquos Ultraviolet Imaging Spectrograph (UVIS) has observed 4stellar and one solar occultation by Enceladusrsquo water vapor plumeThe July 2005 occultation observation established that water is theprimary constituent of the plume [1] and allowed us to calculatethe flux of water coming from the plume the 2007 occultationshowed super-sonic jets of gas imbedded within the plume [2] Thesolar occultation observation set upper limits for N as aconstituent of the plume and provided higher resolution data onthe jets [3] On 19 October 2011 epsilon and zeta Orionis weresimultaneously occulted by the plume The stars were in separatepixels on the detector separated by 24 mrad or ~20 km with thelower altitude star (epsilon Orionis) 18 km above the limb at itsclosest point The profile at two altitudes shows evidence for a newgas jet location possibly between dust jet 50 and 51 identified in[4]Results from the assemblage of these data sets with implicationsfor the composition and vertical structure of the plume and jetswill be described Gas being expelled from the ldquotiger striperdquo fissuresis largely on a vertical escape trajectory away from EnceladusUpper limits are set for water vapor near the limb at latitudes wellaway from the south pole at 3 x 10 cm Upper limits are set forthe amount of ethylene and H in the plume two species ofinterest to the chemistry of the plume [5] No hydrogen or oxygenemission features have been observed from Enceladusrsquo water vaporplume in contrast to the purported plumes at Europa probablydue to the very different plasma environment at Saturn Data havenow been processed consistently for all occultations with slightlydifferent results for water vapor supply to the Saturnmagnetosphere than previously reported Overall eruptive activityhas been steady to within ~20 from 2005 to 2011References [1] Hansen C J et al Science 3111422 (2006)Hansen C J et al Nature 456477 (2008) [3] Hansen C J et alGRL 38L11202 (2011) [4] Porco C C et al Ast J 14845(2014) [5] Glein C R et al GCA 162202 (2015)

Author(s) Candice Hansen Larry Esposito Josh Colwell Amanda Hendrix Ganna Portyankina Don Shemansky RobertWestInstitution(s) 1 JPL CIT 2 PSI 3 Space EnvironmentTechnologies 4 University of Central Florida 5 University ofColorado

41105 ndash The lsquoExcessrsquo Emission from the Warm SurfaceAdjacent to Active Fissures on Enceladus fromCombined VIMS and CIRS SpectraThe exciting discovery of thermal emission from the tiger stripefissures at the S pole of Enceladus is a major highlight of theCassini mission Both VIMS (Visible and Infrared MappingSpectrometer) and CIRS (Composite InfraRed Spectrometer)detect the thermal lsquoblackbodyrsquo spectrum emitted from the warmfissure areas The VIMS instrument is uniquely suited tomeasuring the hottest active locations because VIMS covers the 3to 5 micron wavelength range where the rising edge of the Planckfunction for these T~200 K areas dominates the emission

2 11 1

2

22

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2 5 42 5 3

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128

spectrum At longer wavelengths the spectrum is morecomplicated because contributions from small hot areas and largercooler areas combine to form the broad emission spectrum that isdetected by the CIRS instrument at wavelengths gt67 microns It isthe combination of VIMS and CIRS spectra that paint a morecomplete portrait of the fissure heat transfer processes Usingspectra that span both the VIMS and CIRS wavelengths places astronger constraint on the T distribution near the fissures thanconsideration of the spectra from either instrument aloneWe show that when the best (= highest spatial resolution 800mpixel and smaller) VIMS and CIRS spectra of the fissure thermalemission are considered together there is a large (up to 400)component of lsquoexcessrsquo emission spanning 7 to 17 microns thatrequires explanation New analysis of ~2 km spatial resolutionVIMS spectra of the Damascus hot spot on 8132010 are similar tothe highest resolution 4142012 VIMS Baghdad spectraconfirming that differences in location or time between the bestVIMS and CIRS spectra do not explain away the excess Theobvious interpretation is that there are processes that transfer heatfrom the fissure eruption to the surface within 400 m of the fissurecenter in addition to heat conduction through the fissure wallsCandidate heat transfer processes include fallback of large warmlow velocity ice particles from the edges of the plume andcondensation of the low velocity component of water vaporexpanding outward from the edge of the plumeThis research was conducted at the Jet Propulsion LaboratoryCalifornia Institute of Technolgy Pasadena CA

Author(s) Jay D Goguen Bonnie J Buratti Robert RHowellInstitution(s) 1 JPL 2 University of Wyoming

41106 ndash A 1-D evolutionary model for icy satellitesapplied to EnceladusA 1-D long-term evolution code for icy satellites is presented whichcouples multiple processes water migration geochemicalreactions water and silicate phase transitions crystallizationcompaction by self-gravity and ablation The code takes intoaccount various energy sources tidal heating radiogenic heatinggeochemical energy released by serpentinization or absorbed bymineral dehydration gravitational energy and insolation Itincludes heat transport by conduction convection and advectionThe code is applied to Enceladus by guessing the initial conditionsthat would render a structure compatible with present-dayobservations and adopting a homogeneous initial structureAssuming that the satellite has been losing water continually alongits evolution it follows that it was formed as a more massive moreice-rich and more porous object and gradually transformed into itspresent day state due to sustained tidal heating Several initialcompositions and evolution scenarios are considered and theevolution is simulated for the age of the Solar System The resultscorresponding to the present configuration are confronted with theavailable observational constraints The present configuration isshown to be differentiated into a pure icy mantle several tens ofkm thick overlying a rocky core composed of dehydrated rock inthe central part and hydrated rock in the outer part Such adifferentiated structure is obtained not only for Enceladus but forother medium size ice-rich bodies as wellPredictions for Enceladus are a higher rockice mass ratio thanpreviously assumed and a thinner ice mantle compatible withrecent estimates based on gravity field measurements Althoughobviously the 1-D model cannot be used to explain localphenomena it sheds light on the internal structure invoked inexplanations of localized features and activities

Author(s) Dina Prialnik Uri MalamudInstitution(s) 1 Tel Aviv University

412 ndash Irregular Satellites41201 ndash The Himalia Satellite Group A Case Study onthe Dynamical Self-spreading of Families of IrregularSatellites and Asteroids

Many of the outer planets irregular satellites are grouped intofamilies thought to originate from collisional fragmentation(Nesvornyacute et al 2004 AJ) Interestingly families associated withthe largest irregulars are either more dispersed than expected (egJ6 Himalia Nesvornyacute et al 2003 AJ) or do not exist at all (eg S9Phoebe Ćuk et al 2003 DDA meeting 34) Christou (2005Icarus) found that gravitational scattering by Himalia of its owngroup could explain the large velocity dispersion found byNesvornyacute et al (2003 AJ) At the same time Christou identified anew type of dynamical mechanism that intermittently locks thenode of the satellite J10 Lysithea to that of Himalia The samemechanism but due to Ceres was recently found to operate withinthe Hoffmeister family dispersing its members and allowing anestimate of its age (Novaković et al 2015 ApJ)Here we revisit the issue of family self-dispersion aiming to betterunderstand it by studying its effects on the Himalia group For thiswe utilise (a) intensive test particle simulations on a larger scalethan those by Christou (2005 Icarus) (b) a semi-analyticaltreatment of the new resonance based on the secular theory ofcoorbital motion by Namouni (1999 Icarus) This has allowed us toobtain firmer constraints on the rate of dispersion over time and onhow the resonance affects the long-term evolution of the orbitalelements A principal result of this work is that particles near theresonance evolve differently than those away from it During themeeting we will present a new estimate of the familyrsquos age as wellas an analysis of the resonant structure and how it affects Himaliafamily members We will also discuss the broader implications forthe long-term evolution of orbital concentrations of small bodies inthe solar systemAstronomical research at the Armagh Observatory is funded by theNorthern Ireland Department of Culture Arts and Leisure (DCAL)

Author(s) Daohai Li Apostolos A ChristouInstitution(s) 1 Armagh Observatory

41202 ndash Lightcurves for 25 Irregular Satellites ofSaturnThis abstract reports rotational-lightcurve observations of irregularmoons of Saturn based on disk-integrated observations with theNarrow-Angle Camera of the Cassini spacecraft For 16 objectssynodic rotation periods have been derived at lt1 accuracy for 6others at lower accuracy or with an ambiguity with respect to theamount of maxima and minima The average of all 22 measuredperiods lies between 16 and 19 h For the 19 objects with periodsfaster than 24 h the average is ~125 hThe objects were observed at phase angles between 2deg and 143degAmong the lightcurves obtained at low phases (lt ~45deg) ~85exhibit 2 maxima and 2 minima while only ~15 show3max3min For mid-phase lightcurves (~45deg to ~90deg) the ratiobetween 2max2min and 3max3min lightcurves is almost equalAt high phases (gt ~90deg) only ~13 of the lightcurves display2max2min while ~23 show 3max3min or even 4max4min Forlow- and mid-phase angles the lightcurve amplitudes clearlyincrease with increasing phase While ~50 of the objects showlightcurves with amplitudes below ~04 mag at low phases wefound almost no such small amplitudes for mid and high phasesBetween mid- and high-phase angles the trend of magnitudeincrease lessens The most extreme measured amplitudes were~25 magNo object with a period close to the spin barrier for Main Beltasteroids (~23 h) was detected By assuming a bulk density of theSaturnian irregulars of ~1 g cm the fastest measured period of55 h would be close to the spin barrier for these objectsA comparison of the irregular moons rotation periods with fiveorbit parameters indicates possible weak correlations with two ofthem Periapses and co-latitude of the orbit pole (i with i = i forprograde i = 180deg-i for retrograde moons i is the objects orbitinclination) For moons with orbits of high i gt ~27deg no fast rotator(P lt 10 h) has been found and their average rotation period is~17x longer than for the low-i objects The five fastest rotators areall members of the low-i group A null hypothesis claiming thatobjects of the two inclination bins come from the same populationis rejected at the 95 confidence level

1 12

1 1

1 1

-3

129

Author(s) Tilmann Denk Stefano MottolaInstitution(s) 1 DLR 2 Freie Universitaumlt

41204 ndash Radial Profiles of Saturnrsquos Phoebe RingIn 2009 the Spitzer observatory discovered a vast circumplanetarydust ring around Saturn sourced by its swarm of irregularsatellites This material had been hypothesized to exist in order toblanket Iapetusrsquo leading face and create its stark hemisphericaldichotomy Unfortunately observations from near-Earth spacecannot probe how far inward the Phoebe ring extends as they areoverwhelmed by scattered light from the planet Additionally todate such measurements have only been achieved of thermalemission in the mid-infraredBy contrast we present results from recent observations with theCassini spacecraft (in orbit about Saturn) at optical wavelengthsUsing a novel observational technique that exploits the movingshadow cast by Saturn we mitigate the scattered light andbackground and have been able to clearly extract the exceedinglyfaint Phoebe ring signal (line-of-sight optical depth of 10e-9surface brightness of roughly 27 magarcsec^2)Our extracted albedos are consistent with dark material liberatedfrom the irregular satellites Additionally we present reconstructedradial profiles over the broad range of distances from Saturnspanned by our observations We also connect these results totheoretical models of the size-dependent dynamics of Phoebe ringdust grains under the action of the relevant perturbations

Author(s) Daniel Tamayo Stephen Markham Matthew MHedman Joseph A BurnsInstitution(s) 1 Cornell University 2 University of Idaho 3University of Toronto at Scarborough

413 ndash 67PChuryumov-Gerasimenko41301 ndash The nucleus of comet 67P through the eyes ofthe OSIRIS camerasThe Rosetta spacecraft is studying comet 67PChuryumov-Gerasimenko from a close distance since August 2014 Onboard thespacecraft the two scientific cameras the OSIRIS narrow- and thewide-angle camera are observing the cometary nucleus its activityas well as the dust and gas environmentThis overview paper will cover OSIRIS science from the early arrivaland mapping phase the PHILAE landing and the escort phaseincluding the two close fly-bys With a first characterization ofglobal physical parameters of the nucleus the OSIRIS cameras alsoprovided the data to reconstruct a 3D shape model of the comet anda division into morphologic sub-units From observations ofnear-surface activity jet-like features can be projected onto thesurface and active sources can be correlated with surface featureslike cliffs pits or flat planes The increase of activity during andafter perihelion in August 2015 showed several outbursts whichwere seen as strong collimated jets originating from the southernhemisphereA comparison of results between different Rosetta instruments willgive further inside into the physics of the comets nucleus and itscoma The OSIRIS and VIRTIS instruments are particularly wellsuited to support and complement each other With an overlap inspectral range one instrument can provide the best spatialresolution while the other is strong in the spectral resolution Asummary on collaborative efforts will be given

Author(s) Carsten Guettler Holger Sierks CesareBarbieri Philippe Lamy Rafael Rodrigo Detlef Koschny Hans Rickman The OSIRIS Team Fabrizio Capaccioni Gianrico Filacchione Mauro Ciarniello Stephane Erard Giovanna Rinaldi Federico TosiInstitution(s) 1 Centro de Astrobiologiacutea CSIC-INTA 2European Space Research and Technology CentreESA 3 INAF 4LAM (Laboratoire dAstrophysique de Marseille) 5 Max PlanckInstitute for Solar System Research 6 Observatoire de Paris 7University of Padova 8 Uppsala University

41302 ndash Interpretation of spectrophotometric surface

properties of comet 67PChuryumov-Gerasimenko bylaboratory simulations of cometary analogsThe OSIRIS imaging system [1] onboard European Space AgencyrsquosRosetta mission has been orbiting the comet 67PChuryumov-Gerasimenko (67P) since August 2014 It provides an enormousquantity of high resolution images of the nucleus in the visiblespectral range 67P revealed an unexpected diversity of complexsurface structures and spectral properties have also been measured[2]To better interpret this data a profound knowledge of laboratoryanalogs of cometary surfaces is essential For this reason we haveset up the LOSSy laboratory (Laboratory for Outflow Studies ofSublimating Materials) to study the spectrophotometric propertiesof ice-bearing cometary nucleus analogs The main focus lies onthe characterization of the surface evolution under simulated spaceconditions The laboratory is equipped with two facilities thePHIRE-2 radio-goniometer [3] designed to measure thebidirectional visible reflectance of samples under a wide range ofgeometries and the SCITEAS simulation chamber [4] designed tostudy the evolution of icy samples subliming under lowpressuretemperature conditions by hyperspectral imaging in theVIS-NIR range Different microscopes complement the twofacilitiesWe present laboratory data of different types of fine grained iceparticles mixed with non-volatile components (complex organicmatter and minerals) As the ice sublimes a deposition lag ofnon-volatile constituents is built-up on top of the ice possiblymimic a cometary surface The bidirectional reflectance of thesamples have been characterized before and after the sublimationprocessA comparison of our laboratory findings with recent OSIRIS data[5] will be presented[1] Keller H U et al 2007 Space Sci Rev 128 26[2] Thomas N 2015 Science 347 Issue 6220 aaa0440[3] Jost B submitted Icarus[4] Pommerol A et al 2015 Planet Space Sci 109106-122[5] Fornasier S et al in press Icarus arXiv150506888

Author(s) Bernhard Jost Antoine Pommerol OlivierPoch Nathalie Carrasco Cyril Szopa Nicolas ThomasInstitution(s) 1 Center for Space and Habitability University ofBern 2 LATMOS-IPSL Universiteacute Versailles St-Quentin 3Physics Institute University of Bern

41303 ndash Photometric properties of the nucleus of67PChuryumov-Gerasimenko from OSIRISRosettaspace telescope and ground-based observationsIn-situ imaging of the nucleus of comet 67PChuryumov-Gerasimenko by the OSIRIS Narrow Angle Camera (NAC) allowsan in depth characterization of its photometric properties that canbe compared with remote observations thus helping in theinterpretation of other nuclei We performed a photometricanalysis of both unresolved and resolved NAC images of thenucleus obtained during twenty five observational campaignsspreading from 23 March to 6 August 2014 with up to twelve filterswhose spectral coverage extended from 271 to 986 nm An accuratephotometric calibration was obtained from the observations of asolar analog star 16 Cyg B We further combined this analysis withprevious observations obtained with the Hubble and Spitzer spacetelescopes and ground-based telescopes The analysis furtherincorporates the shape model and the rotational state the nucleusof 67P independently determined from the NAC images We willpresent results on the geometric albedo phase function color andthermal properties and put them in the broader context ofproperties of cometary nuclei

Author(s) Philippe L Lamy Guillaume Faury Imre Toth Laurent Jorda Robert Gaskell Olivier Groussin ClaireCapannaInstitution(s) 1 AKKA Technologies 2 Konkoly Observatory3 Laboratoire dAstrophysique de Marseille 4 Planetary ScienceInstitute

41304 ndash The Nucleus and Coma of Comet 67PC-G as

2 1

3 12 1

5 57 4 1 2

8 5 33 3 6

3 3

3 31 2 2 3

3 1 23 4 3

3

130

Seen at Millimeter and Submillimeter Wavelengths bythe MIRO InstrumentThe Microwave Instrument for the Rosetta Orbiter (MIRO) is aUS instrument on the European Space Agencys Rosettaspacecraft currently flying along side comet 67PChuryumov-Gerasimenko MIRO is designed to study the nucleus and coma ofthe comet as a coupled system It makes broad-band continuummeasurements of the thermal emission of the nucleus at 190 and563 GHz (16 and 05 mm) which probe the thermal and dielectricproperties of the nucleus as a function of depth from ~1 mm to ~10cm When looking off the nucleus continuum emission from dustcan be used to constrain the abundance and size distribution ofparticles In addition to its continuum channels MIRO has a highresolution (44 kHz) spectrometer fixed tuned to submillimeterlines of H O H O H O CO NH and three CH OHtransitions All 8 lines have been observed yielding estimates ofthe abundance velocity and temperature of these species in thecoma This talk will provide an overview of the instrument and ourresults to date

Author(s) Mark D Hofstadter Samuel Gulkis Mark Allen Paul von Allmen Gerard Beaudin Nicolas Biver DominiqueBockelee-Morvan Mathieu Choukroun Jacques Crovisier Pierre Encrenaz Therese Encrenaz Margaret Frerking PaulHartogh Wing Ip Michael Janssen Christopher Jarchow Stephen Keihm Seungwon Lee Emmanuel Lellouch CedricLeyrat Ladislav Rezac Frederick Peter Schloerb ThomasSpilkerInstitution(s) 1 JPL 2 Max Planck 3 National CentralUniversity 4 Observatoire de Paris 5 Solar System Science andExploration 6 University of Massachusetts

41305 ndash Search for regional variations of thermal andelectrical properties of comet 67PCG probed byMIRORosettaSince June 2014 The MIRO (Microwave Instrument for RosettaOrbiter) on board the Rosetta (ESA) spacecraft observes comet67P-CG along its heliocentric orbit from 325 AU to 124 AU MIROoperates in millimeter and submillimeter wavelengths respectivelyat 190 GHz (156 mm) and 562 GHz (05 mm) While thesubmillimeter channel is coupled to a Chirp TransformSpectrometer (CTS) for spectroscopic analysis of the coma bothbands provide a broad-band continuum channel for sensing thethermal emission of the nucleus itselfContinuum measurements of the nucleus probe the subsurfacethermal emission from two different depths The first analysis(Schloerb et al 2015) of data already obtained essentially in theNorthern hemisphere have revealed large temperature variationswith latitude as well as distinct diurnal curves most prominent inthe 05 mm channel indicating that the electric penetration depthfor this channel is comparable to the diurnal thermal skin depthInitial modelling of these data have indicated a low surface thermalinertia in the range 10-30 J K-1 m-2 s-12 and probed depths oforder 1-4 cm We here investigate potential spatial variations ofthermal and electrical properties by analysing separately thegeomorphological regions described by Thomas et al (2015) Foreach region we select measurements corresponding to those areasobtained at different local times and effective latitudes We modelthe thermal profiles with depth and the outgoing mm and submmradiation for different values of the thermal inertia and of the ratioof the electrical to the thermal skin depth We will present the bestestimates of thermal inertia and electricthermal depth ratios foreach region selected Additional information on subsurfacetemperature gradients may be inferred by using observations atvarying emergence anglesThe thermal emission from southern regions has been analysed byChoukroun et al (2015) during the polar night Now that the comethas reached perihelion the South Pole is fully illuminatedallowing extension of this study to these regions

Author(s) Cedric Leyrat Doriann Blain EmmanuelLellouch Paul von Allmen Stephen Keihm MatthieuChoukroun Pete Schloerb Nicolas Biver Samuel Gulkis Mark HofstadterInstitution(s) 1 Jet Propulsion Laboratory 2 LESIA -Observatoire de Paris 3 University of Massachusetts

41306 ndash Modeling of the VIRTIS-M Observations ofthe Coma of Comet 67PChuryumov-GerasimenkoThe recent images of the inner coma of 67PChuryumov-Gerasimenko (CG) made by the infrared channel of the VIRTIS-Minstrument on board the Rosetta spacecraft show the gasdistribution as it expands in the coma (Migliorini et al 2015 DPSabstract)Since VIRTIS is a remote sensing instrument a proper modeling ofthese observations requires the computation of the full coma ofcomet CG which necessitates the use of a kinetic approach due tothe rather low gas densities Hence we apply a Direct SimulationMonde Carlo (DSMC) method to solve the Boltzmann equationand describe CGrsquos coma from the nucleus surface up to a fewhundreds of kilometers The model uses the SHAP5 nucleus shapemodel from the OSIRIS team The gas flux distribution takes intoaccount solar illumination including self-shadowing The localactivity at the surface of the nucleus is given by sphericalharmonics expansion reproducing best the ROSINA-DFMS dataThe densities from the DSMC model outputs are then integratedalong the line-of-sight to create synthetic images that are directlycomparable with the VIRTIS-M column density measurementsThe good agreement between the observations and the modelillustrates our continuously improving understanding of thephysics of the coma of comet CGAcknowledgementsWork at UofM was supported by contracts JPL1266313JPL1266314 and NASA grant NNX09AB59G Work at UoB wasfunded by the State of Bern the Swiss National Science Foundationand by the European Space Agency PRODEX Program Work atSouthwest Research institute was supported by subcontract1496541 from the JPL Work at BIRA-IASB was supported by theBelgian Science Policy Office via PRODEXROSINA PEA 90020The authors would like to thank ASI CNES DLR NASA forsupporting this research VIRTIS was built by a consortium formedby Italy France and Germany under the scientific responsibility ofthe IAPS of INAF which guides also the scientific operations Theconsortium includes also the LESIA of the Observatoire de Parisand the Institut fuumlr Planetenforschung of DLR The authors wishto thank the RSGS and the RMOC for their continuous support

Author(s) Nicolas Fougere Michael R Combi ValeriyTenishev Andre Bieler Alessandra Migliorini GiuseppePiccioni Fabrizio Capaccioni Gianrico Filacchione GaborToth Zhenguang Huang Tamas Gombosi Kenneth Hansen Dominique Bockelee-Morvan Vincent Debout StephaneErard Cedric Leyrat Uwe Fink Martin Rubin KathrinAltwegg Chia-Yu Tzou Lena Le Roy Ursina Calmonte Jean-Jacques Berthelier Henri Reme Myrtha Hassig StephenFuselier Bjorn Fiethe Johan De KeyserInstitution(s) 1 Belgian Institute for Space Aeronomy 2Istituto Nazionale di Astrofisica 3 Laboratoire drsquoEtudes Spatialeset drsquoInstrumentation en Astrophysique Observatoire deParisCNRSUniversiteacute Pierre et Marie CurieUniversiteacute Paris-Diderot 4 Southwest Research Institute 5 TU Braunschweig 6Universite de Toulouse 7 University of Arizona 8 University ofBern 9 University of Michigan

41307 ndash Activity and jets of comet 67P as observed byOSIRIS since August 2014Dust jets ie fuzzy collimated streams of cometary material arisingfrom the nucleus have been observed in-situ on all comets sincethe Giotto mission flew by comet 1PHalley in 1986 Yet theirformation mechanism remains unknown Several solutions havebeen proposed from localized physical mechanisms on thesurfacesub-surface to purely dynamical processes involving thefocusing of gas flows by the local topography While the latterseems to be responsible for

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the larger features high resolution imagery has shown that broadstreams are composed of many smaller features (a few meterswide) that connect directly to the nucleus surfaceThe OSIRIS cameras on board Rosetta are monitoring these jets inhigh resolution images since August 2014 We followed this type ofactivity from 36 AU to perihelion (123 AU) We have traced thejets back to their sources on the surface and noticed a goodcorrelation with sub-solar latitude surface morphologies and colorvariations As the comet receives more insolation we observeddifferent type of jets some of them sustained beyond the localsunset and an increasing number of transient events with suddenrelease of gas and dustWe will present here how activity changes with local seasons andhow it contributes to the erosion of the surfaceAcknowledgements OSIRIS was built by a consortium led by theMax-Planck-Institut fuumlr Sonnensystemforschung GoumlttingenGermany in collaboration with CISAS University of Padova Italythe Laboratoire dAstrophysique de Marseille France the Institutode Astrofisica de Andalucia CSIC Granada Spain the ScientificSupport Office of the European Space Agency Noordwijk TheNetherlands the Instituto Nacional de Tecnica AeroespacialMadrid Spain the Universidad Politechnica de Madrid Spain theDepartment of Physics and Astronomy of Uppsala UniversitySweden and the Institut fuumlr Datentechnik undKommunikationsnetze der Technischen Universitaumlt BraunschweigGermany We thank the Rosetta Science Ground Segment at ESACthe Rosetta Mission Operations Centre at ESOC and the RosettaProject at ESTEC for their outstanding work enabling the sciencereturn of the Rosetta Mission

Author(s) Jean-Baptiste Vincent Nilda Oklay MaurizioPajola Sebastian Houmlfner Holger Sierks Cesare Barbieri Philippe Lamy Rafael Rodrigo Hans Rickman DetlefKoschnyInstitution(s) 1 CISAS 2 ESTEC 3 INTA-CSIC 4 LAM 5MPS 6 Uppsala University

41308 ndash Dust Outbursts From Comet67PChuryumov-Gerasimenko Observed byRosetta-AliceThe comet 67PChuryumov-Gerasimenko passed throughperihelion on 13 August 2015 In the weeks surrounding theperihelion passage several dramatic outbursts of dust have beenobserved by instruments aboard ESArsquos Rosetta spacecraft Theseoutbursts are typically intense and short-lived with timescales onthe order of several tens of minutes to a few hours We report onthe two largest of these dusty outbursts observed by the Alicefar-ultraviolet (700-2050Aring) spectrograph which occurred on 10July 2015 and 22 August 2015 On 10 July 2015 0206 UTC Alicespectra of the sunward limb nucleus and anti-sunward limb showtypical levels of dust-scattered sunlight with the sunward limb3-4x brighter than the anti-sunward limb Beginning around 0210UTC the dust on the anti-sunward side of the nucleus brightenedrapidly increasing by a factor of 21 over pre-outburst levels whenintegrated over a 10-minute exposure A 40s exposure beginning at0220 showed an additional factor of two increase in brightnessDuring the outburst the dust became significantly brighter thanthe sunlit nucleus Concurrent NAVCAM images show a large dustcloud expanding out from the night side of the nucleus Despitethis forty-fold increase in dust brightness the Alice data show noevidence of enhancements of H O CO CO O O or H in thepost-outburst spectra By 0424 UTC after a 2-hour data gap thecomet had returned to pre-event levels Although complicated bythe scanning motion of the spacecraft the start of Aliceobservations on 22 August 2015 revealed a major dust outburst inprogress this time confined to the sunward side of the nucleusBetween 0703 and 0754 the brightness of dust on the sunwardside faded by a factor of 7 NAVCAM images from this period alsoshow a dramatic fan-shaped cloud of dust Unlike the 10 Julyevent the 22 August event shows some evidence of increased gasemissions

Author(s) Andrew J Steffl Paul D Feldman Michael FAHearn Jean-Loup Bertaux Lori M Feaga Brian A Keeney Matthew M Knight John Noonan Joel Wm Parker Eric RSchindhelm S Alan Stern Ronald J Vervack Harold AWeaverInstitution(s) 1 Johns Hopkins University 2 Johns HopkinsUniversity Applied Physics Lab 3 LATMOS 4 LowellObservatory 5 Southwest Research Institute 6 Univeristy ofColorado 7 Univeristy of Maryland

41309 ndash Evidence for a precession of the nucleus ofcomet 67PC-G from ROSETTAOSIRIS imagesThe retrieval of the rotational parameters of comet 67PC-G is partof the shape reconstruction process conducted from data collectedby the OSIRIS imaging system aboard ROSETTA Among otherparameters this includes the reconstruction of the (RADec)direction of the Z axis of the body-fixed frame and that of theangular momentum vector The stereophotogrammetric solution(Preusker et al AampA 2015 in press) obtained in Aug-Sep 2014already showed evidence for a complex rotation of comet 67PC-GA subsequent analysis of the rotational data obtained using thestereophotoclinometry method (Gaskell et al MPampS 43 10492008) up to April 2015 also revealed a precession with a likelihoodgreater than 9999 The amplitude and period of the (RADec)variations measured with both methods are fully compatibleWe propose an interpretation of the measured period as acombination of torque free motions a rotation combined with aprecession of small amplitude The modeling of this motion hasimplications on the value of the moments of inertia from which itis possible to constrain the internal density distribution of comet67PC-G

Author(s) Laurent Jorda Pedro Gutierrez BjoernDavidsson Robert Gaskell Stubbe Hviid Horst Uwe Keller Lucie Maquet Stefano Mottola Frank Preusker FrankScholtenInstitution(s) 1 European Space Agency 2 German AerospaceCenter (DLR) 3 Instituto de Astrofisica de Andalucia 4Laboratoire dAstrophysique de Marseille 5 Planetary ScienceInstitute 6 Technical University of Braunschweig 7 University ofUppsala

41310 ndash The interior of 67PC-G nucleus revealed byCONSERT measurements and simulationsThe CONSERT bistatic radar onboard the Rosetta spacecraft andthe Philae lander has begun to reveal the internal structure ofComet 67PChuryumov-Gerasimenko through radio tomographicmapping between the lander and main spacecraft The small lobewas found to be structurally homogeneous at the spatial scale often meters corresponding to a few wavelengths of CONSERTinstrument [1] The real part of the relative permittivity has beenderived from the travel time of the strongest signals obtained on12-13 November 2014 from Philae final landing site Since the finalposition of the lander was not accurately defined numerousray-tracing simulations were performed to constrain theambiguities on Philae position using the known position of Rosettaand the propagation time and paths inside and outside the nucleusA least square statistical analysis between measurements andsimulations lead to deduce a bulk relative permittivity about (127 plusmn01) meanwhile the uncertainty in the lander location was reducedto an area of about 21 by 34 square meters [1]Ongoing theoretical and experimental simulations are providingmore insights on the nucleus properties Numerical ray-tracingsimulations of the propagation at grazing angles have beenperformed for various subsurface permittivity models Theyestablish that a permittivity gradient in the shallow sub-surfacewould have a strong effect on the wave propagation Thepermittivity probably decreases with depth suggesting that asignificant increase of dustice ratio with depth is unlikely [2]Laboratory simulations of the permittivity of subsurface cometaryanalog materials [3] and of surface porous analog samples [4]have taken place Results suggest 67P dielectric properties to bemainly controlled by porosity the dustice volumetric ratio torange from 04 to 26 and the porosity to range from 75 to 85 [1]

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Further on-going laboratory measurements will be discussedSupports from CNES and NASA are acknowledged[1] Kofman et al Science 349 6247 aab0639 2015[2] Ciarletti et al AampA (Rosetta issue) in press 2015[3] E Heggy et al Icarus 221 925 2012[4] Brouet et al AampA (Rosetta issue) in press 2015

Author(s) A Levasseur-Regourd Wlodek Kofman AlainHerique Valeacuterie Ciarletti Essam Heggy Jeacutereacutemie LasueInstitution(s) 1 IPAG-CNRS 2 IRAP-OMP CNRS-UPS 3University of Southern California 4 UPMC (Sorbonne Univ) 5UVSQ (UPSay)

41311 ndash 3D reconstruction of the final PHILAE landingsite AbydosThe Abydos region is the region of the final landing site of thePHILAE lander The landing site has been potentially identified onimages of this region acquired by the OSIRIS imaging systemaboard the orbiter before (Oct 22 2014) and after (Dec 6-13 2014)the landing of PHILAE (Lamy et al in prep) Assuming that thisidentification is correct we reconstructed the topography of Abydosin 3D using a method called ``multiresolution photoclinometry bydeformation (MPCD Capanna et al The Visual Computer29(6-8) 825-835 2013) The method works in two steps (a) aDTM of this region is extracted from the global MPCD shapemodel (b) the resulting triangular mesh is progressively deformedat increasing spatial resolution in order to match a set of 14 imagesof Abydos at pixel resolutions between 1 and 8 m The method usedto perform the image matching is the L-BFGS-b non-linearoptimization (Morales et al ACM Trans Math Softw 38(1) 1-42011)In spite of the very unfavourable illumination conditions weachieve a vertical accuracy of about 3 m while the horizontalsampling is 05 m The accuracy is limited by high incidence angleson the images (about 60 deg on average) combined with a complextopography including numerous cliffs and a few overhangs Wealso check the compatibility of the local DTM with the imagesobtained by the CIVA-P instrument aboard PHILAE If the Lamy etal identification is correct our DTM shows that PHILAE landed ina cavity at the bottom of a small cliff of 8 m height

Author(s) Claire Capanna Laurent Jorda Philippe Lamy Gilles Gesquiegravere Ceacutedric Delmas Joeumllle Durand PhilippeGaudon Eric JuradoInstitution(s) 1 CNES 2 Laboratoire dAstrophysique deMarseille 3 LIRIS

41312 ndash Report on the ground-based observationcampaign of 67PChuryumov-GerasimenkoRosetta gets closer to the nucleus than any previous mission andreturns wonderfully detailed measurements from the heart of thecomet but at the cost of not seeing the large scale coma and tailsThe ground-based campaign fills in the missing part of the picturestudying the comet at about 1000 km resolution and followinghow the overall activity of the comet varies These data providecontext information for Rosetta so changes in the inner coma seenby the spacecraft can be correlated with the phenomena observablein comets This will not only help to complete our understanding ofthe activity of 67P but also to allow us to compare it with othercomets that are only observed from the groundThe ground-based campaign includes observations with nearly allmajor facilities world-wide In 2014 the majority of data came fromthe ESO VLT as the comet was still relatively faint and in Southernskies but as it returns to visibility from Earth in 2015 it isconsiderably brighter approaching its perihelion in August and atNorthern declinations I will present results from the 2014campaign including visible wavelength photometry andspectroscopy and the latest results from 2015 observations

Author(s) Emmanuel JehinInstitution(s) 1 Universiteacute de Liegravege

41313 ndash Hubble Space Telescope Imaging Polarimetryof Comet 67PChuryumov-Gerasimenko Obtained

During the Rosetta MissionWe present pre- and post-perihelion high-spatial resolution (005arcsecpixel) 06 micron imaging polarimetry of Comet67PChuryumov-Gerasimenko taken with the Advanced Camerafor Surveys aboard the Hubble Space Telescope (HST) Thepre-perihelion observations were obtained at two epochs chosen tobracket the times when the closest orbits of Rosetta were flown(down to 10 km for extended periods 2014-Aug-19 r = 352 au Δ= 276 au α asymp 120˚) and the Philae landing took place (2014-Nov-17 r = 296 au Δ = 343 au α asymp 157˚) Our preliminaryanalyses of both pre-perihelion epochs shows that the polarizationposition angle lies in the scattering plane thus is negative with adegree of polarization p asymp -2 The two post-perihelion epochswere matched to the first time after perihelion that the comet wasobservable with HST (2015-Oct-10 r = 143 au Δ = 180 au α asymp335˚) and when the comet was again viewed at small phase angle(2016-Feb-19 r = 240 au Δ = 149 au α asymp 120˚) We discuss ourpolarimetry results in context with in situ measurements of dustparticles obtained with the Rosetta spacecraft

Author(s) Dean C Hines Anny-Chantal Levasseur-Regourd Edith Hadamcik Vadym Kaydash Matthew M Knight

Ludmilla Kolokolova Jian-Yang Li Carey M Lisse KarriMuinonen Max Mutchler Yuriy Shkuratov ColinSnodgrass Michael L Sitko Matt G G T Taylor GordenVideen Padmavati A Yanamandra-Fisher Evgenij ZubkoInstitution(s) 1 Applied Physics Laboratory 2 ESA ESTEC 3Kharkov National University 4 Lowell Observatory 5 MPI forSolar System Research 6 Planetary Science Institute 7 SpaceScience Institute 8 Space Telescope Science Institute 9 Universityof Helsinki 10 University of Helsinki 11 University of Maryland12 UPMC (Sorbonne Univ) 13 UPMC LATMOS

41314 ndash Water production rates of recent comets(2015) by SOHOSWAN and the SOHOSWAN surveyThe all-sky hydrogen Lyman-alpha camera SWAN (Solar WindAnisotropies) on the SOlar and Heliospheric Observatory (SOHO)satellite makes observations of the hydrogen coma of comets Mostwater molecules produced by comets are ultimatelyphotodissociated into two H atoms and one O atom producing ahuge atomic hydrogen coma that is routinely observed in the dailyfull-sky SWAN images in comets of sufficient brightness Waterproduction rates are calculated using our time-resolved model(Maumlkinen amp Combi 2005 Icarus 177 217) typically yielding about1 observation every 2 days on the average for each comet Here wedescribe the progress in analysis of observations of cometsobserved in 2015 and those selected from the archive for analysisThese include comets C2013 US10 (Catalina) C2014 Q1(PanSTARRS) and possibly 67PChuryumov-Gerasimenko Astatus update on the entire SOHOSWAN archive of waterproduction rates in comets will also be given SOHO is aninternational cooperative mission between ESA and NASA Supportfrom grants NNX11AH50G from the NASA Planetary AstronomyProgram and NNX13AQ66G from the NASA Planetary MissionData Analysis Program are gratefully acknowledged as is supportfrom CNRS CNES and the Finnish Meteorological Institute(FMI)

Author(s) Michael R Combi J T T Maumlkinen Jean-LoupBertaux Eric Queacutemerais Steacutephane FerronInstitution(s) 1 ACRI-st 2 Finnish Meteorologoical Institute3 LATMOSIPSI Universiteacute de Versailles Saint-Quentin 4 Univof Michigan

41315 ndash The primordial nucleus of Comet67PChuryumov-GerasimenkoObservations of Comet 67PChuryumov-Gerasimenko by Rosettashow that the nucleus is bi-lobed extensively layered has a lowbulk density a high dust-to-ice mass ratio (implying high porosity)and weak strength except for a thin sintered surface layer Thecomet is rich in supervolatiles (CO CO2 N2) may containamorphous water ice and displays little to no signs of aqueousalteration Lack of phyllosilicates in Stardust samples from Comet81PWild 2 provides further support that comet nuclei did not

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contain liquid waterThese properties differ from those expected for 50-200 kmdiameter bodies in the primordial disk We find that thermalprocessing due to Al-26 combined with collisional compactioncreates a population of medium-sized bodies that are comparablydense compacted strong heavily depleted in supervolatilescontaining little to no amorphous water ice and that haveexperienced extensive aqueous alteration Irregular satellitesPhoebe and Himalia are potential representatives of thispopulation Collisional rubble piles inherit these properties fromtheir parents We therefore conclude that observed comet nucleiare primordial rubble piles and not collisional rubble pilesWe propose a concurrent comet and TNO formation scenario thatis consistent with these observations We argue that TNOs formdue to streaming instabilities at sizes of about 50-400 km and thatabout 350 of these grow slowly in a low-mass primordial disk to thesize of Triton causing little viscous stirring during growth Wepropose a dynamically cold primordial disk that preventsmedium-sized TNOs from breaking into collisional rubble pilesand allows for the survival of primordial rubble-pile comets Weargue that comets form by hierarchical agglomeration out ofmaterial that remains after TNO formation This slow growth isnecessary to avoid thermal processing by Al-26 and to allow cometnuclei to incorporate 3 Myr old material from the inner SolarSystem found in Stardust samples Growth in the Solar Nebulacreates porous single-lobe nuclei while continued growth in amildly viscously stirred primordial disk creates denser outer layersand allow bi-lobe nucleus formation through mergers

Author(s) Bjorn Davidsson Holger Sierks CarstenGuettler Francesco Marzari Maurizio Pajola HansRickman Michael AHearn Anne-Therese Auger MohamedEl-Maarry Sonia Fornasier Pedro Gutierrez Horst UweKeller Matteo Massironi Colin Snodgrass Jean-BaptisteVincent Cesare Barbieri Philippe Lamy Rafael Rodrigo Detlef Koschny Antonella Barucci Jean-Loup Bertaux Ivano Bertini Gabriele Cremonese Vania Da Deppo StefanoDebei Mariolino De Cecco Clement Feller Marco Fulle Olivier Groussin Stubbe Hviid Sebastian Hoefner Wing-Huen Ip Laurent Jorda Joerg Knollenberg GaborKovacs Joerg-Rainer Kramm Ekkehard Kuehrt MichaelKueppers Fiorangela La Forgia Luisa Lara MonicaLazzarin Jose Lopez Moreno Richard Moissl-Fraund Stefano Mottola Giampiero Naletto Nilda Oklay NicolasThomas Cecilia TubianaInstitution(s) 1 Aix Marseille Universite CNRS LAM(Laboratoire dAstrophysique de Marseille) 2 Centro deAstrobiologia CSIC-INTA 3 Centro di Ateneo di Studi ed AttivitaSpaziali Giuseppe Colombo (CISAS) University of Padova 4CNR-IFN UOS Padova LUXOR 5 Department of IndustrialEngineering ndash University of Padova 6 Deutsches Zentrum fuerLuft- und Raumfahrt (DLR) 7 INAF - Osservatorio Astronomico8 INAF Osservatorio Astronomico di Padova VicolodellOsservatorio 9 Institut fuer Geophysik und extraterrestrischePhysik (IGEP) Technische Universitaet Braunschweig 10Instituto de Astrofisica de Andalucia (CSIC) 11 LaboratoiredrsquoAstrophysique de Marseille 12 LATMOS CNRSUVSQIPSL 13LESIA-Observatoire de Paris CNRS Universite Pierre et MarieCurie Universite Paris Diderot 14 Max-Planck-Institut fuerSonnensystemforschung 15 National Central UniversityGraduate Institute of Astronomy 16 Operations DepartmentEuropean Space Astronomy CentreESA 17 PAN Space ResearchCenter 18 Physikalisches Institut der Universitaet Bern 19Planetary and Space Sciences Department of Physical SciencesThe Open University 20 Scientific Support Office European SpaceResearch and Technology CentreESA 21 University of MarylandDepartment of Astronomy 22 University of Padova Departmentof Information Engineering 23 University of PadovaDepartment of Physics and Astronomy 24 University of PadovaDepartment of Physics and Astronomy Vicolo dellOsservatorio25 University of Trento 26 University of Uppsala Dept ofPhysics and Astronomy

41316 ndash Comet 67P observations with LOTUS a newnear-UV spectrograph for the Liverpool Telescope

The European Space Agencyrsquos Rosetta spacecraft has been orbitingcomet 67PChuryumov-Gerasimenko (hereinafter ldquo67Prdquo) sinceAugust 2014 providing in-situ measurements of the dust gas andplasma content of the coma within ~100km of the nucleusSupporting the mission is a world-wide coordinated campaign ofsimultaneous ground-based observations of 67P (wwwrosetta-campaignnet) providing wider context of the outer coma and tailinvisible to Rosetta We can now compare these observationsaugmented by ground truth from Rosetta with those of othercomets past and future that are only observed from EarthThe robotic Liverpool Telescope (LT) is part of this campaign dueto its unique ability to flexibly and autonomously schedule regularobservations over entire semesters Its optical imagery has recentlybeen supplemented by near-UV spectroscopy to observe the UVmolecular bands below 4000Aring that are of considerable interest tocometary science The LTs existing spectrographs FRODOSpec andSPRAT cut off at 4000Aring so the Liverpool Telescope Optical-to-UVSpectrograph - LOTUS - was fast-track designed built anddeployed on-sky in just five months LOTUS contains no movingparts acquisition is made with the LTs IOO imaging camera anddifferent width slits for calibration and science are selected byfine-tuning the telescopes pointing on an innovative step designin its single slitWe present here details of the LOTUS spectrograph and somepreliminary results of our ongoing observations of comet 67P

Author(s) Jon Marchant Helen Jermak Iain Steele ColinSnodgrass Alan Fitzsimmons Geraint JonesInstitution(s) 1 Liverpool John Moores University 2 QueensUniversity Belfast 3 The Open University 4 University CollegeLondon

414 ndash Active Asteroids41402 ndash The Reactivation of Main-Belt Comet 324PLaSagra (P2010 R2)We present observations using the Baade Magellan and Canada-France-Hawaii telescopes showing that main-belt comet 324PLaSagra formerly known as P2010 R2 has become active again forthe first time since originally observed to be active in 2010-2011The object appears point-source-like in March and April 2015 as itapproached perihelion (true anomaly of ν~300 deg) but was ~1mag brighter than expected if inactive suggesting the presence ofunresolved dust emission Activity was confirmed by observationsof a cometary dust tail in May and June 2015 We find an apparentnet dust production rate of lt01 kgs during these observations324P is now the fourth main-belt comet confirmed to berecurrently active a strong indication that its activity is driven bysublimation It now has the largest confirmed active range of alllikely main-belt comets and also the most distant confirmedinbound activation point at R~28 AU Further observations duringthe current active period will allow direct comparisons of activitystrength with 324Prsquos 2010 activity

Author(s) Henry H Hsieh Scott SheppardInstitution(s) 1 Carnegie Institution for Science 2 PlanetaryScience Institute

41403 ndash Evidence for an Impact Event on (493)GriseldisAn extended feature associated with the main-belt asteroid (493)Griseldis has been detected in three R-band exposures of 330 to350 sec duration spanning 5 hours taken on 2015 Mar 17 UT withthe HyperSuprimeCam instrument on the 8-m Subaru telescopeAdditional observations of Griseldis were taken with the 65-mMagellan telescope on 2015 Mar 21 UT and the extended featurewas still detected though weaker No extended feature wasdetected in one unfiltered 600 sec exposure taken with the 22-mUniversity of Hawaii telescope on 2015 Mar 24 UT or in Magellanimages taken on 2015 Apr 18 and May 21 UT Griseldis is a 46 kmdiameter P-type asteroid with semimajor axis of 312 AUeccentricity of 017 inclination of 15 deg and Tisserand parameterof 3187 relative to Jupiter The heliocentric distance on 2015 Mar

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17 was 333 AU thus the asteroid was closer to aphelion than it wasto perihelion The most recent perihelion passage was on 2013 Aug17 and the orbital period is 55 years Additional images in theSubaru and CTIO DECam archives from 2010 and 2012respectively show no signs of activity The position angle of theextended feature does not match either the antisolar direction orthe negative velocity vector of the asteroid The rotationallightcurve of Griseldis is known to show a peak-to-peak amplitudeof up to 045 mag over a 52-hour period No anomalousbrightening of the asteroid is evident in the 2015 photometryreported along with the astrometry of this object The observationsare consistent with the occurrence of an impact event on thisasteroid Additional analysis of the images is in progress

Author(s) David J Tholen Scott S Sheppard Chad ATrujilloInstitution(s) 1 Carnegie Inst 2 Gemini Obs 3 Univ ofHawaii

41404 ndash Thermal alteration in carbonaceouschondrites and implications for sublimation in rockcometsRock comets are small solar system bodies in Sun-skirting orbits(perihelion q lt ~015 AU) that form comae rich in mineralsublimation products but lack typical cometary ice sublimationproducts (H2O CO2 etc) B-class asteroid (3200) Phaethonconsidered to be the parent body of the Geminid meteor shower isthe only rock comet currently known to periodically eject dust andform a coma Thermal fracturing or thermal decomposition ofsurface materials may be driving Phaethonrsquos cometary activity (Li ampJewitt 2013) Phaethon-like asteroids have dynamically unstableorbits and their perihelia can change rapidly over their ~10 Myrlifetimes (de Leoacuten et al 2010) raising the possibility that otherasteroids may have been rock comets in the past Here we proposeusing spectroscopic observations of mercury (Hg) as a tracer of anasteroidrsquos thermal metamorphic history and therefore as aconstraint on its minimum achieved perihelion distanceB-class asteroids such as Phaethon have an initial compositionsimilar to aqueously altered primitive meteorites such as CI- orCM-type meteorites (Clark et al 2010) Laboratory heatingexperiments of ~mm sized samples of carbonaceous chondritemeteorites from 300K to 1200K at a rate of 15Kminute showmobilization and volatilization of various labile elements attemperatures that could be reached by Mercury-crossing asteroidsSamples became rapidly depleted in labile elements and inparticular lost ~75 of their Hg content when heated from~500-700 K which corresponds to heliocentric distances of~015-03 au consistent with our thermal models Mercury hasstrong emission lines in the UV (~ 185 nm) and thus its presence(or absence) relative to carbonaceous chondrite abundances wouldindicate if these bodies had perihelia in their dynamical historiesinside of 015 AU and therefore may have previously beenPhaethon-like rock comets Future space telescopes orballoon-borne observing platforms equipped with a UVspectrometer could potentially detect the presence or absence ofstrong ultraviolet mercury lines on rock comets or rock cometcandidates

Author(s) Alessondra Springmann Dante S Lauretta Jordan K SteckloffInstitution(s) 1 Purdue University 2 University of Arizona

415 ndash Comets Physical CharacteristicsDynamics and Composition41501 ndash Sizing Up the Comets The NEOWISE MissionSurvey of Cometary NucleiiThe NEOWISE mission has provided the largest cometary surveyin the infrared The NEOWISE mission was originally anaugmentation to detect solar system objects and specifically NearEarth Objects using the Wide-Field Infrared Survey Explorer(WISE) spacecraft Funded by NASAs Planetary Division throughthe Near-Earth Object Observation program NEOWISE detected

moving objects throughout the WISE mission[1-2] after which thespacecraft was placed in a state of hybernation After 32 monthsthe re-christened NEOWISE spacecraft was returned to a zenith-pointing orbit On December 23 2013 the reactivated surveybegan[3]While NEOWISEs primary purpose was the detection of NEOs atotal of 163 comets have been identified in the prime survey(January 7 2010 - Febraury 1 2011) and over 75 have beenobserved during the NEOWISE reactivate mission to date Theseobservations have been made at multiple epochs often when thecomets were at large heliocentric distances or exhibited little or noactivity Preliminary analysis of the 25 NEOWISE-discoveredcomets has indicated possible differences between the sizedistributions of long-period comets (LPCs) and short-periodcomets (SPCs) in their raw (not de-biased) samples[4] On averagethe observed LPCs were larger than the SPCs We will discuss theresults of the analysis of the larger sample of more than 65 nucleiiextracted from the prime mission data as well as the reactivatedmission sampleThis publication makes use of data products from the Wide-fieldInfrared Survey Explorer which is a joint project of the Universityof California Los Angeles and the Jet PropulsionLaboratoryCalifornia Institute of Technology funded by theNational Aeronautics and Space Administration as well as dataproducts from NEOWISE which is a project of JPLCaltechfunded by the Planetary Science Division of NASA RS SS and EKwere supported by the NASA Postdoctoral Program[1] Cutri et al 2013 (httpwise2ipaccaltechedudocsreleaseallskyexpsupindexhtml)[2] Mainzer et al 2011 ApJ 731 53[3] Mainzer et al 2014 ApJ 792 30[4] Bauer J M et al 2015The NEOWISE-Discovered CometPopulation and the CO+CO2 production rates ApJ Submitted

Author(s) James M Bauer Tommy Grav A K Mainzer Emily Kramer Rachel A Stevenson Yanga R Fernaacutendez Joseph R Masiero Carolyn R Nugent Roc M Cutri SarahSonnett Frank J Masci Karen J Meech Russel Walker Carey M Lisse Paul R Weissman John W Dailey NathanBlair Andrew Lucas Robert S McMillan Edward L WrightInstitution(s) 1 Applied Physics Laboratory Johns HopkinsUniversity 2 Department of Astronomy University of California3 Infrared Analysis and Processing Center (IPAC) CaliforniaInstitute of Technology 4 Institute for Astronomy University ofHawaii 5 Jet Propulsion Lab 6 Lunar and PlanetaryLaboratory University of Arizona 7 Monterey Institute forResearch in Astronomy 8 Planetary Science Institute 9University of Central Florida

41502 ndash Investigating the Effects of Temperature onthe Signatures of Shocks Propagated Through Impactsinto Minerals Found in Comets and AsteroidsComets and asteroids are subjected to extremely cold conditionsthroughout their lifetimes During their sojourns in the solarsystem they are subjected to collisions at speeds that are easilycapable of generating shock waves in their constituent materials Inaddition to ices more common silicate minerals such as olivinesand pyroxenes are important components of these objects Thecollision-induced shocks could affect the spectral signatures ofthose mineral components which could in turn be detectedtelescopically We have embarked on a project to determine howimpact-generated shock might affect the reflectance spectra andstructures of select silicates as both impact speed and targettemperature are varied systematicallyWhile the effects of impact speed (in the form of shock stress) onnumerous materials have been and continue to be studied the roleof target temperature has received comparatively little attentionpresumably because of the operational difficulties it can introduceto experimentation Our experiments were performed with thevertical gun in the Experimental Impact Laboratory of the JohnsonSpace Center A liquid-nitrogen system was plumbed to permitcooling of the target container and its contents under vacuum totemperatures as low as -100degC (173 K) Temperatures weremonitored by thermocouples mounted on the outside of the target

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container Because those sensors were not in contact with thetarget material at impact the measured temperatures are treated aslower limits for the actual values Peridot (Mg-rich olivine) andenstatite (Mg-rich orthopyroxene) were used as targets whichinvolved the impact of alumina (Al O ) spheres at speeds of 20 ndash27 km s and temperatures covering 25degC to -100degC (298 K to 173K) We have begun collecting and analyzing data in the near tomid-IR with a Fourier-transform infrared spectrometer andpreliminary analyses show that notable differences inabsorption-band strength and position occur as functions of bothimpact speed (peak shock stress) and initial temperatureFunding was provided by the NASA PGampG grant 09-PGG09-0115NSF grant AST-1010012 Special thanks to the NASA EIL staff FCardenas and R Montes

Author(s) Susan M Lederer Elizabeth A Jensen MichaelFane Douglas C Smith Jacob Holmes Lindsay P Keller SeanS Lindsay Diane H Wooden Mark J Cintala Michael EZolenskyInstitution(s) 1 Cal State Univ SB 2 NASA Ames ResearchCenter 3 NASA Johnson Space Center 4 Planetary ScienceInstitute 5 Univ of Oxford

41503 ndash High precision comet trajectory estimatesthe Mars flyby of C2013 A1 (Siding Spring)The Mars flyby of C2013 A1 (Siding Spring) represented a uniqueopportunity for imaging a long-period comet and resolving itsnucleus and rotation period Because of the small encounterdistance and the high relative velocity the goal of successfullyobserving C2013 A1 from the Mars orbiting spacecrafts posedstrict requirements on the accuracy of the comet ephemerisestimate These requirements were hard to meet as comets areknown for being highly unpredictable astrometric observationscan be significantly biased and nongravitational perturbationssignificantly affect the trajectory Therefore we remeasured acouple of hundred astrometric positions from images provided byground-based observers and also observed the comet with the MarsReconnaissance Orbiterrsquos HiRISE camera on 2014 October 7 Inparticular the HiRISE observations were decisive in securing thetrajectory and revealed that nongravitational perturbations werelarger than anticipated The comet was successfully observed andthe analysis of the science data is still ongoing By adding somepost-encounter data and using the Rotating Jet Model fornongravitational accelerations we constrain the rotation pole ofC2013 A1

Author(s) Davide Farnocchia Steven R Chesley MarcoMicheli Alan Delamere Rodney S Heyd David J Tholen JonD Giorgini William M Owen Leslie K TamppariInstitution(s) 1 Delamere Support Services 2 ESA NEOCoordination Center 3 Institute for Astronomy University ofHawaii 4 Jet Propulsion Laboratory California Institute ofTechnology 5 Planetary Image Research Laboratory Lunar andPlanetary Laboratory University of Arizona

41504 ndash The Resolved Nucleus and Coma of CometSiding Spring from MRO ObservationsComet Siding Spring (C2013 A1) is a dynamically new cometdiscovered on January 4 2013 On October 19 2014 just 6 dayspefore perihelion Siding Spring made an historic close approach(CA) to Mars closing to a distance of only 140500 km We usedthe HiRISE camera on the Mars Reconaissance Orbiter to observethe comet from October 17-20 (CA-60 hr to CA+15 hrs) obtaining122 images primarily in broadband filters centered near 500 (BG)and 700 (RED) nm with another filter near 900 (IR) nm addednear close approach The HiRISE pixel scale in these observationsis as small as 138 mpix essentially making this event a fortuitousnatural flyby of a dynamically new cometEnhancement of the closest approach images using both anunsharp mask and a coma fitting and subtraction routine reveals asharply-defined crescent that changes its appearance as the viewinggeometry varies during the comets passage The crescent is likelythe illuminated limb of the nucleus making this the first occasionon which the nucleus of a dynamically new comet has been

resolved Preliminary analyses indicate that the nucleus iselongated (prolate ellipsoid) with a length on the order of akilometerPhotometric measurements of the coma in a constant 48-kmradius aperture show brightness variations in the RED filtersequence with a periodicity of 81 hr Because this is a measure ofdust production the single-peaked lightcurve represents therotation period of the nucleus During the observations oneprimary fan feature is seen in the coma The lightcurve variationswith amplitude of ~40 (60-140) of the average brightness in the48 km aperture correlate to the feature visibility indicating thatthe jet that produces it is the primary source of activity The shapeand direction of the fan suggests that the source is near a poleproducing a cone of dust around the spin axis We anticipate thatthe long time baseline and wide range of viewpoints covered in theMRO images will be useful in computing an independent poleorientation

Author(s) Tony L Farnham W Alan Delamere MichaelSP Kelley Rodney Heyd Jian-Yang LiInstitution(s) 1 Delamere Support Services 2 Lunar andPlanetary Laboratory 3 Planetary Science Institute 4 Univ ofMaryland

41505 ndash Comparing CN Features in Two Comets1PHalley and 103PHartley 2Comets 1PHalley and 103PHartley 2 show distinct CN features intheir respecive comae Both comets are non-principal-axis rotators1PHalley is the proto-type for Halley-type comets with the OortCloud as its possible source region whereas 103PHartley 2 is aJupiter-Family comet that possibly originated from the Kuiper BeltBoth comets were spacecraft targets and studied widely from bothspace and from the groundWe will discuss the properties of CN features and in particular thebehavior of the derived outflow velocities based on the CN featurespresent in the groundbased coma images of these two comets Thecorresponding heliocentric distances for CN images of comet1PHalley range from approximately 08 AU to 20 AU (during itspost-perihelion leg of the 1986 apparition) For CN images ofcomet 103PHartley 2 the corresponding heliocentric distancesrange from 131 AU through the perihelion (at 106 AU) to 125 AU(during its 2010 apparition)Ultimately these results will be used to understand the rotationalstates and the activity behaviors of these two comets

Author(s) Nalin H Samarasinha Cassandra Lejoly JoseBarrera Beatrice Mueller David SchleicherInstitution(s) 1 Lowell Observatory 2 Planetary ScienceInstitute

41506 ndash Rotational Spin-up Caused CO Outgassingon Comet 103PHartley 2The Deep Impact spacecraftrsquos flyby of comet 103PHartley 2 onNovember 4 2010 revealed its nucleus to be a small bilobate andhighly active world [1] [2] The bulk of this activity is driven by COsublimation which is enigmatically restricted to the tip of the smalllobe [1] Because Hartley 2s CO production responds to thediurnal cycle of the nucleus [1] CO ice must be no deeper than afew centimeters below the surface of the small lobe However thehigh volatility of CO would suggest that its sublimation frontshould recede deep below the surface such that diurnal volatileproduction is dominated by more refractory species such as waterice as was observed at comet Tempel 1 [3]Here we show that both the near surface CO ice and its geographicrestriction to the tip of the small lobe suggest that Hartley 2recently experienced an episode of fast rotation We use theGRAVMAP code to compute the stability of slopes on the surface ofHartley 2 as a function of spin period We determine that thesurface of the active region of Hartley 2rsquos small lobe becomesunstable at a rotation period of ~10-12 hours (as opposed to itscurrent spin period of ~ 18 hours [1]) and will flow toward the tipof the lobe excavating buried CO ice and activating CO -drivenactivity However the rest of the surface of the nucleus is stable atthese spin rates and will therefore not exhibit CO activity We

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additionally use Finite Element Model (FEM) analysis todemonstrate that the interior of Hartley 2rsquos nucleus is structurallystable (assuming a cohesive strength of at least 5 Pa) at these spinratesThe uncommonly high angular acceleration of Hartley 2 which haschanged the nucleus spin period by two hours in three months [4]suggests that this episode of fast rotation may have existed only afew years or decades ago Thus Hartley 2 may provide an excellentcase study into the reactivation of quiescent comet nuclei viarotational spin up as would result from weak homogeneous gasemissions via the SYORP EffectReferences [1] AHearn et al Science 332 1396 (2011) [2] Thomaset al Icarus 222 550 (2013) [3] Feaga et al Icarus 190 345 (2007)[4] Samarasinha amp Mueller Ap J 775L10 (2013)

Author(s) Jordan Steckloff Kevin Graves MasatoshiHirabayashi James RichardsonInstitution(s) 1 Arecibo Observatory 2 Purdue University 3University of Colorado

41507 ndash The Distribution of Geometric Albedos ofJupiter-Family Comets From SEPPCoN and Visible-Wavelength PhotometryWe present a preliminary estimate of the distribution of geometricalbedos among the Jupiter-family comet (JFC) population Whilean assumption of 4 is common and consistent with theheretofore limited number of known cometary albedos the trueaverage albedo and albedo spread have not been well constrainedBy knowing a statistically-significant number of albedos and thusthe distribution of albedo values across the comet population wecan investigate overarching science questions about the evolutionof cometary surfaces Our current work makes use of and builds onthe results of the Survey of Ensemble Physical Properties ofCometary Nuclei (SEPPCoN) in which we obtained new andindependent estimates of the radii of 89 JFCs [12] By using thethus-known radius and photometry of a bare nucleus we canconstrain its geometric albedo We will present our preliminaryalbedo estimates for ~50 JFC nuclei and we will discuss theimplications of the ensemble of the results These JFCs were allobserved in R-band and were all observed at relatively largeheliocentric distances (usually gt4 AU from the Sun) where thecomets appeared inactive thus minimizing coma contaminationWe acknowledge the support of NASA grant NNX09AB44G of NSFgrant AST-0808004 and of the Astrophysical ResearchConsortiumApache Point Observatory for this work References[1] Y R Fernandez et al 2013 Icarus 226 1138 [2] M S Kelley etal 2013 Icarus 225 475

Author(s) Yanga R Fernandez Harold Weaver CareyLisse Karen Meech Stephen Lowry James Bauer AlanFitzsimmons Colin SnodgrassInstitution(s) 1 CaltechJPL 2 JHU APL 3 Open Univ 4Queens Univ Belfast 5 UH-IfA 6 Univ Kent 7 Univ of CentralFlorida

41508 ndash The physical properties of water ice incomets a comparative studyDetections of water ice in comets are notably scarce (~10 comets)and our knowledge of cometary ice remains poor As such we arenot able to consider water-ice characteristics in the evaluation ofcomet nuclei formation scenarios despite water ice being the majorcomponent of comets To overcome this deficiency we have beguna systematic low-resolution near-infrared spectroscopic survey tolook for and characterize water-ice grain halos in cometary comaeThe ultimate goal is to survey a large sample of Jupiter-family andOort cloud comets to understand the conditions that favor thedetectability of a comets water-ice grain halo and the factors ifany that may control the observed water-ice properties We reporton the modeling approach to determine the relative abundances ofthe major components within the coma their grain sizes and thetype of mixing (mixed within the coma or mixed within eachaggregate) We present results on a selected set of comets that wereobserved prior and during our survey

Author(s) Silvia Protopapa Michael SP Kelley Bin Yang Jacqueline Keane Jessica Sunshine Michael F AHearn Ludmilla KolokolovaInstitution(s) 1 European Southern Observatory 2 Universityof Hawaii 3 University of Maryland

41509 ndash Volatile Composition of Comet C2012 K1(PanSTARRS)On 2014 May 22 and 24 we characterized the volatile compositionof the dynamically new Oort Cloud comet C2012 K1 (PanSTARRS)using the long-slit high resolution (λΔλ asymp 25000) infared echellespectrograph (NIRSPEC) at the 10m Keck 2 telescope onMaunakea HI We detected fluorescent emission from six primaryspecies (H O HCN CH C H CH OH and CO) and promptemission from one product species (OH - a directory proxy for H-

O) Upper limits were derived for C H and H CO We reportrotational temperatures production rates and mixing ratios(relative to water) Based on the inventory of comets characterizedto date mixing ratios of trace gases in C2012 K1 (PanSTARRS) areabout normal ndash CH OH and C H are slightly enriched CO CH HCN and H CO are average and C H is depleted I will discussC2012 K1 (PanSTARRS) in the context of an emerging taxonomyfor comets based on volatile compositionThis work is supported through the NASA Missouri Space GrantConsortium and the National Science Foundation (NSF 1211362)the NASA Astrobiology Institute through a grant to the GoddardCenter for Astrobiology (81107302120391) and the NASAPlanetary Astronomy Program (81107302030343)

Author(s) Nathan Roth Erika Gibb Boncho P Bonev Michael A DiSanti Geronimo L Villanueva Lucas Paganini Michael J MummaInstitution(s) 1 Catholic University of America 2 NASAGoddard Space Flight Center 3 University of Missouri - St Louis

41510 ndash The Volatile Composition of Comet C2013 V5(Oukaimeden) from Infrared SpectroscopyWe obtained high-quality pre-perihelion spectra of long-periodcomet C2013 V5 (Oukaimeden) on 2014 September 5 and 6 (R =078 AU) with NIRSPEC at Keck 2 and on September 13 (R =050 AU) with CSHELL at the NASA-IRTF Our observationstargeted nine primary volatiles (ie native ices) H2O CO H2COCH3OH HCN NH3 C2H2 CH4 C2H6 Comparison ofabundance ratios for trace volatiles relative to H2O with thosemeasured for other comets reveals an overall depleted chemistry inOukaimedenWe gratefully acknowledge support from NASA PlanetaryAtmospheres Planetary Astronomy and Astrobiology programsand NSF Astronomy and Astrophysics Research Grants

Author(s) Michael A DiSanti Boncho P Bonev Erika LGibb Nathan X Roth Geronimo L Villanueva LucasPaganini Michael J MummaInstitution(s) 1 CUA 2 NASAs GSFC 3 University ofMissouri-St Louis

41511 ndash The favorable apparition of comet C2014 Q2(Lovejoy) and unique insights from ground-based IRobservationsIn February 2015 we observed comet C2014 Q2 (Lovejoy) on twoconsecutive nights using NIRSPEC at the Keck Observatory inHawaii Comet Q2 underwent strong activity and a favorableapparition which triggered astronomical observing campaignsworldwide and yielded unique scientific results over a range ofwavelength regimes From the infrared (IR) observations weretrieve production rates temperatures cosmogonic parametersand abundances of native species (ie volatiles released directlyfrom the nucleus) that are of unique importance in theinterpretation of global properties and highly complementary tomeasurements performed at other wavelengths both of native andproduct species in the coma Our measurements show detection ofseveral molecules we typically detect in the IR and strongunidentified lines We also performed a deep search for HDOemission lines yielding constraints of the DH ratio We will

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discuss our preliminary results in the context of complementarystudies of C2014 Q2 and compare the measured abundances withthose in other comets

Author(s) Lucas Paganini Michael J Mumma Erika LGibb Michael A DiSanti Stefanie N Milam Boncho PBonev Martin A Cordiner Steven Charnley Sara Faggi Geronimo L VillanuevaInstitution(s) 1 INAF - Osservatorio Astrofisico di Arcetri 2NASA Goddard Space Flight Center 3 University of Missouri StLouis

41512 ndash Outgassing and chemical evolution of C2012S1 (ISON)Volatile production rates relative abundances rotationaltemperatures and spatial distributions in the coma were measuredin C2012 S1 (ISON) using long-slit high-dispersion (λΔλ ~25000) infrared spectroscopy as part of a worldwide observingcampaign Spectra were obtained on UT 2013 October 26 and 28with NIRSPEC at the W M Keck Observatory and UT 2013November 19 and 20 with CSHELL at the NASA IRTF H O wasdetected on all dates with production rates increasing by about afactor of 40 between October 26 (R = 112 AU) and November 20(R = 043 AU) Short-term variability of H O was also seen as theproduction rate increased by nearly a factor of two duringobservations obtained over a period of about six hours onNovember 19 C H CH OH and CH abundances were slightlydepleted relative to H O in ISON compared to mean values forcomets measured at infrared wavelengths On the November datesC H HCN and OCS abundances relative to H O appear to beclose to the range of mean values whereas H CO and NH weresignificantly enhanced We will compare derived chemicalabundances in ISON to other comets measured with infraredspectroscopy

Author(s) Neil Dello Russo Ronald J Vervack HideyoKawakita Anita Cochran Adam J McKay Walter M Harris Harold A Weaver Carey M Lisse Michael A DiSanti HitomiKobayashi Nicolas Biver Dominique Bockeleacutee-Morvan Jacques Crovisier Cyrielle Opitom Emmanuel JehinInstitution(s) 1 JHU-APL 2 Koyama AstronomicalObservatory Kyoto Sangyo University 3 LESIA Observatoire deParis 4 Lunar and Planetary Laboratory University of Arizona5 McDonald Observatory 6 NASA-GSFC 7 Universiteacute de Liegravege

41513 ndash Coma in Comet C2012 S1 (ISON) at ~4 auWe analyze HST observations of Comet ISON (C2012 S1) atheliocentric distance ~4 au and phase angle ~12ndash14 degree Theinner coma (lt 5000 km) reveals two polarimetric features positivedegree of linear polarization P = (248 plusmn 045) at projecteddistances less than 236 km and negative polarization P = ndash (16 plusmn045) at 1000 ndash 5000 km [Hines et al 2014 ApJL 780 L32] Atthese projected distances average color slope was found to be ~6per 100 nm [Li et al 2013 ApJL 779 L3] When consideredsimultaneously these two features place significant constraint onthe physical and chemical properties of dust particles [Zubko et al2015 Planet Space Sci httpdxdoiorg101016jpss201508002]We model this response with agglomerated debris particles havinghighly irregular morphology and density of constituent materialbeing consistent with in situ studies of comets We considerparticles of 28 different refractive indices that correspond to in situstudies of comets and plausible assumptions on chemicalcomposition of cometary dust and ices What emerges from ouranalysis is that the ISON coma was chemically heterogeneous atthe epoch of observation The positive polarization at smallprojected distances suggests a high spatial concentration of highlyabsorbing materials such as amorphous carbon andor organicshighly irradiated with UV radiation At larger distances thenegative polarization P = ndash (16 plusmn 045) and color slope ~6 per100 nm appear consistent with organics slightly processed with UVradiation tholins Mg-Fe silicates and Mg-rich silicatescontaminated with ~10 (by volume) amorphous carbon Asignificant abundance of pure water-ice particles andor pure

Mg-rich silicates must be ruled out in this region These materialshave been found in situ in other comets and also detected withimaging polarimetry in the circumnucleus halo regions Analyses ofpolarimetric images suggest that Mg-rich silicates could originatefrom a refractory surface layer on the surface of cometary nuclei[Zubko et al 2012 AampA 544 L8] A depletion of such particles inComet ISON could imply an absence of such a layer on its nucleus

Author(s) Gorden Videen Evgenij Zubko Dean C Hines Yuriy Shkuratov Vadym Kaydash Karri Muinonen MatthewW Knight Michael L Sitko Carrey M Lisse Max Mutchler Diane H Wooden Jian-Yang Li Hiroshi KobayashiInstitution(s) 1 Johns Hopkins University APL 2 NagoyaUniversity 3 NASA Ames Research Center 4 Planetary ScienceInstitute 5 Space Science Institute 6 Space Telescope ScienceInstitute 7 University of Helsinki 8 VN Karazin KharkovNational University

41514 ndash Radio OH spectroscopic mapping survey of 26comets Trends in outflow velocity and collisionalquenchingBetween 2000-2015 we obtained 18cm OH spectra of 26 cometsusing the Arecibo Observatory 305m Gordon Telescope and theNational Radio Astronomy Observatory 100m R W Byrd GreenBank Telescope (GBT) Spectra of both long-period and periodiccomets were obtained at 1667 and 1665 MHz (18cm wavelength)with a beam resolution of 29 arcminutes at Arecibo and 74arcminutes at GBT Heliocentric distances for comets in the samplerange between 04 to 28 AU with gas production rates from01--30 x 10 mols A wide range of gas velocities are observedfrom 05 to nearly 2 kms with the highest variability in outflowvelocities for comets at heliocentric distances less than 1 AUMapping observations provide a direct constraint on the radiuswithin which there is collisional quenching an important factor inestimating total water production rates and a useful constraint oncoma density We find that collisional quenching variesconsiderably and generally exceeds what might be expectedtheoretically so it is best when observations make a directconstraint on this value We will present aggregate velocity gasproduction and quenching results from this comet survey derivedfrom a kinetic model utilizing Monte Carlo simulations

Author(s) Amy J Lovell Ellen S HowellInstitution(s) 1 Agnes Scott College 2 LPLU Arizona

41515 ndash High-resolution spectroscopy of the CN redsystem in comet C2013 R1 (Lovejoy) using WINEREDat Koyama Astronomical ObservatoryCN radical has the strong electronic transition moments in opticalwavelength region and CN has extensively observed in cometsEspecially the CN violet system (B Σ mdashX Σ ) has been observedby using high-resolution spectroscopic technique in order to inferthe isotopic ratios of carbon and nitrogen in comets via C N

C N and C N However the wavelength range for thissystem (~388 nm) is severely extinct if a comet is close to the Sun(we have to observe the comet at low elevations from theground-based observatories) On the other hand CN radical alsohas the strong electronic transition in near-infrared (~11 microns)the CN red system (A Π mdashX Σ ) Although there are few reportson the high-resolution spectra of this band in comets thiswavelength region is not severely affected by the telluric extinctionand considered as the new window for the observations of thecarbon and nitrogen isotopic ratios in cometsHigh resolution near-infrared spectra of comet C2013 R1(Lovejoy) using the WINERED (R~3x10 ) spectrometer mountedon the 13-m Araki telescope at Koyama Astronomical Observatorywere acquired on UT 2013 Nov 30 The heliocentric and geocentricdistances were 091 AU and 049 AU respectively We detectedstrong emission lines of the CN red system (00) at around 11microns The rotational line intensities of this band approximatelyfollow the Boltzmann distribution at ~300K for our observationsWe present the detailed analysis of the CN red system in cometC2013 R1 (Lovejoy) and discuss about the isotopic ratios in CN

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This research program is supported by the MEXT --- SupportedProgram for the Strategic Research Foundation at PrivateUniversities 2014 ndash 2018 and partially supported by JSPS15J10864

Author(s) Hideyo Kawakita Yoshiharu Shinnaka SoheiKondo Satoshi Hamano Hiroaki Sameshima KenshiNakanishi Takafumi Kawanishi Tetsuya Nakaoka ShogoOtsubo Masaomi Kinoshita Yuji Ikeda Ryo Yamamoto Natsuko Izumi Kei Fukue Chikako Yasui Hiroyuki Mito Yuki Sarugaku Noriyuki Matsunaga Naoto KobayashiInstitution(s) 1 Kyoto Sangyo University 2 LIH KoyamaAstronomical Observatory 3 National AstronomicalObservatory 4 University of Tokyo

41516 ndash Nitrogen Isotopic Ratios in Cometary NH Implication for N-fractionation in AmmoniaIsotopic ratios in cometary molecules are diagnostic for thephysico-chemical conditions where molecules formed and areprocessed from the interstellar medium to the solar nebulaUsually temperatures at the molecular formation control thefractionation of the heavier element in molecular species egD-fractionation in waterIn cometary volatiles the N N ratios in CN have been wellobserved (Manfroid et al 2009 AampA 503 613 and referencetherein) and is consistent with the ratio in HCN (a most probableparent of CN) measured in few comets (Bockeleacutee-Morvan et al2008 ApJ 679 L49) Those ratios are enriched compared to theproto-solar value by a factor of ~3 In contrast to those Nitrilesthere are only few reports on N N ratios in Ammonia (asAmine) (Rousselot et al 2014 ApJ 780 L17 Shinnaka et al 2014ApJ 782 L16) Ammonia (NH ) is usually the most abundant andHCN is the second most abundant N-bearing volatiles in cometaryice Especially recent observations of NH revealed the N Nratios in NH are comparable to those of CN However from theviewpoint of theoretical work the enrichment of N in cometaryNH cannot be reproduced by current chemical network modelsInformation about the diversity of the N N ratios in NH ofindividual comets is needed to understand the formationmechanismsenvironments of NH in the early solar systemTo clarify the diversity of the N N ratios in cometary NH wedetermine the N N ratios in NH for more than ten cometsindividually which include not only Oort cloud comets but alsoshort period comets by using the high-resolution optical spectra ofNH These spectra were obtained with both the UVES mountedon the VLT in Chile and the HDS on the Subaru Telescope inHawaiiThe derived N N ratios in NH for more than ten comets showhigh N-enrichment compared with the elemental abundances ofnitrogen in the Sun by about factor of ~3 and has no large diversitydepending on these dynamical properties We discuss about theorigin of the formation conditions of cometary NH and itsphysico-chemical evolution in the solar nebula based on our andother resultsThis work was supported by JSPS 15J10864 (Y Shinnaka)

Author(s) Yoshiharu Shinnaka Hideyo Kawakita Emmanueumll Jehin Alice Decock Damien Hutsemeacutekers JeanManfroid Akira AraiInstitution(s) 1 Koyama Astronomical Observatory of KyotoSangyo University 2 LESIA Observatoire de Paris 3 NationalAstronomical Observatory of Japan 4 Universiteacute de Liegravege

41517 ndash Spectroscopic studies of the molecularparentage of radical species in cometary comaeWe have observed several comets using an integral-field unitspectrograph (the George and Cynthia Mitchell Spectrograph) onthe 27m Harlan J Smith telescope at McDonald ObservatoryFull-coma spectroscopic images were obtained for various radicalspecies (C2 C3 CH CN NH2) By constructing azimuthal averageprofiles from the full-coma spectroscopic images we can test Hasermodel parameters with our observations The Haser model wasused to determine production rates and possible parent lifetimesthat would be consistent with the model By iterating through a

large range of possible parents lifetimes we can see what range ofvalues in which the Haser model is consistent with observationsAlso this type of analysis gives us perspective on how sensitive themodels fit quality is to changes in parent lifetimes Here wepresent the work completed to date and we compare our results toother comet taxonomic surveys

Author(s) Benjamin Lewis Donna Pierce Anita CochranInstitution(s) 1 Mississippi State University 2 UT-Austin

41518 ndash Gone in a Blaze of Glory the Demise of CometC2015 D1 (SOHO)We present studies of C2015 D1 (SOHO) the first sunskirtingcomet ever seen from ground stations over the past half centuryThe Solar and Heliospheric Observatory (SOHO) witnessed itspeculiar light curve with a huge dip followed by a flareup aroundperihelion the dip was likely caused by sublimation of olivinesdirectly evidenced by a coincident temporary disappearance of thetail The flareup likely reflects a disintegration event which wesuggest was triggered by intense thermal stress established withinthe nucleus interior Photometric data reveal an increasingly dustycoma indicative of volatile depletion A catastrophic mass loss rateof ~10 kg s around perihelion was seen Ground-basedXingming Observatory spotted the post-perihelion debris cloudOur morphological simulations of post-perihelion images findnewly released dust grains of size a gt~ 15 μm in radius however atemporal increase in a was also witnessed possibly due to swiftdispersions of smaller grains swept away by radiation forceswithout replenishment Together with the fading profile of the lightcurve a power law dust size distribution with index γ = 32 plusmn 01 isderived We detected no active remaining cometary nuclei over~01 km in radius in post-perihelion images acquired at LowellObservatory Applying radial non-gravitational parameter A =(1209 plusmn 0118) times 10 AU day from an isothermal water-icesublimation model to the SOHO astrometry significantly reducesresiduals and sinusoidal trends in the orbit determination Thenucleus mass ~10 --10 kg and the radius ~50--150 m (bulkdensity ρ = 04 g cm assumed) before the disintegration arededuced from the photometric data consistent results weredetermined from the non-gravitational effects

Author(s) Man-To Hui Quan-Zhi Ye Matthew ManningKnight Karl Battams David ClarkInstitution(s) 1 Department of Earth Planetary and SpaceSciences UCLA 2 Department of Physics and AstronomyUniversity of Western Ontario 3 Lowell Observatory 4 NavalResearch Laboratory

41519 ndash The Plasma Environment in Comets Over aWide Range of Heliocentric Distances Application toComent C2006 P1 (McNaught)On 2007 January 12 comet C2006 P1 (McNaught) passed itsperihelion at 017 AU Abundant remote observations offer plentyof information on the neutral composition and neutral velocitieswithin 1 million kilometers of the comet nucleus In early Februarythe Ulysses spacecraft made an in situ measurement of the ioncomposition plasma velocity and magnetic field when passingthrough the distant ion tail and the ambient solar wind Themeasurement by Ulysses was made when the comet was at around08 AU With the constraints provided by remote and in situobservations we simulated the plasma environment of CometC2006 P1 (McNaught) using a multi-species comet MHD modelover a wide range of heliocentric distances from 017 to 175 AUThe solar wind interaction of the comet at various locations ischaracterized and typical subsolar standoff distances of the bowshock and contact surface are presented and compared to analyticsolutions We find the variation in the bow shock standoffdistances at different heliocentric distances is smaller than thecontact surface In addition we modified the multi-species modelfor the case when the comet was at 07 AU and achievedcomparable water group ion abundances proton densities plasmavelocities and plasma temperatures to the UlyssesSWICS andSWOOPS observations We discuss the dominating chemicalreactions throughout the comet-solar wind interaction region and

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demonstrate the link between the ion composition near the cometand in the distant tail as measured by Ulysses The work at theUniversity of Michigan was supported by the NASA PlanetaryAtmospheres grant NNX14AG84G

Author(s) Yinsi Shou Michael Combi Yingdong Jia Tamas Gombosi Gabor Toth Martin RubinInstitution(s) 1 UCLA 2 University of Bern 3 University ofMichigan

41520 ndash Planets Perturbing Planetoids How Clear IsThe NeighborhoodIAU Resolution B5 adopted in Prague in 2006 states that acelestial body needs to have cleared the neighbourhood around itsorbit to qualify as a planet Pluto orbits within the Kuiper Belt soit does not meet this criterion but presumably the existence ofEarth-crossing asteroids does not disqualify the Earth fromplanetary status Stern and Levison (2002) Soter (2006) andMargot (2015) used equivalent criteria for planethood based on agravitational scattering parameter Λ which is proportional to thesquare of the planets mass and inversely proportional to its orbitalperiod This parameter assumes the small bodies to be clearedbegin with orbits like that of the planet In reality small bodies arefed in to the region of the planet at a more-or-less steady rate forinstance some main-belt asteroids become Near-Earth Asteroidswhile Kuiper Belt Objects can become Centaurs I will presentorbital integrations of small bodies from their source regions toquantify their steady-state populations at each planet in our SolarSystem and will compare the results with predictions from arefined version of the Λ parameterMargot J-L (2015) arXiv150706300Soter S (2006) Astron J 132 2513-2519Stern SA Levison HF (2002) in Highlights of Astronomy Vol12 pp 205-213

Author(s) Henry C (Luke) DonesInstitution(s) 1 Southwest Research Inst

41521 ndash Finding long-lost Comet LexellComet D1770 L1 (Lexell) made the closest observed pass by acomet to the Earth at approximately 0015 AU on 1 July 1770 Anaked-eye object observed by many astronomers of the time it wassubsequently lost the best contemporary estimates had it removedfrom its 1770 orbit by Jupiter in 1779 and sent to the outer SolarSystemNear-Earth asteroid 2010 JL33 has an orbit similar to that followedby Lexells comet during its observed apparition However thisNEAs nominal orbit which is well-known on the basis of adecade-long arc which includes radar observations does notapproach the Earth at the correct time to be Lexells comet That isunless modest non-gravitational forces are applied in which casethe famous near-miss can be reproducedModern measurements of 2010 JL33 together with those Lexellscomet made in the 18th century -which include motion exceeding40 degrees per day on the sky at closest approach- provideexquisite constraints on the dynamical processes at workcometary Yarkovsky or other I will discuss the implications of andthe conditions required for asteroid 2010 JL33 to be in factlong-lost comet Lexell

Author(s) Paul WiegertInstitution(s) 1 Univ of Western Ontario

41522 ndash A Continuing Analysis of Possible ActivityDrivers for the Enigmatic Comet 29PSchwassmann-Wachmann 1We present results from our continuing effort to understandactivity drivers in Comet 29PSchwassmann-Wachmann 1 (SW1)While being in a nearly circular orbit around 6 AU SW1 iscontinuously active and experiences frequent outbursts Ourgrouprsquos effort is focusing on finding constraints on physical anddynamical properties of SW1rsquos nucleus and their incorporation intoa thermophysical model [12] to explain this behavior Now we areanalyzing coma morphology of SW1 before during and after

outburst to place constraints on the spin-pole direction spinperiod and surface areas of activity (a spin period lower limit hasbeen measured) Also we are using the thermal model toinvestigate if the continuous activity comes from one or multipleprocesses such as the release of trapped supervolatiles during theamorphous to crystalline (A-C) water ice phase transition andorthe direct sublimation of pockets of supervolatile ices which maybe primordial or from the condensation of gases released duringthe A-C phase transition To explain the possibly quasi-periodic butfrequent outbursts we are looking into subsurface cavities whereinternal pressures can build reaching and exceeding surroundingmaterial strengths [34] andor thermal waves reaching a pocket ofsupervolatile ices causing a rapid increase in the sublimation rateFor all these phenomena the model is constrained by comparingthe output dust mass loss rate and its variability with what has beenobserved through optical imaging of the comet at various points inits orbit We will present preliminary thermal modeling of ahomogeneous progenitor nucleus that evolves into a body showinginternal material layering the generation of CO and CO2 icepockets and the production of outbursts thus bringing us closer toexplaining the behavior of this intriguing comet[1] Sarid G et al 2005 PASP 117 843 [2] Sarid G 2009 PhDThesis Tel Aviv Univ [3] Gronkowski P 2014 Astron NachrAN2 No 335 124-134 [4] Gronkowski P and Wesolowski M2015 MNRAS 451 3068-3077 We thank the NASA Outer PlanetsResearch Program (NNX12AK50G) and the Center for Lunar andAsteroid Surface Science (CLASS NNA14AB05A) for support ofthis work

Author(s) Charles Alfred Schambeau Yanga Fernandez Nalin Samarasinha Gal Sarid Beatrice Mueller Karen Meech Laura WoodneyInstitution(s) 1 California State University San Bernardino 2Florida Space Institute 3 Institute for Astronomy 4 PlanetaryScience Institute 5 University of Central Florida

41523 ndash Investigating the Spatial Structure of HCNEmission in Comet C2012 F6 (Lemmon)Comets are of particular interest in the field of Astrochemistry asthey can be used as a direct probe of formation chemistry of theSolar System Originating in the Oort Cloud reservoir these longperiod objects experience relatively limited solar influence Themajority of cometary material (water methane and ammonia ices)has remained in the same state as when it formed These ices areprecursors to more complex molecules which have been shown toform amino acids that are crucial for the development of life HCNor hydrogen cyanide is of particular interest because it can formthe nucleobase adenine (C H N ) The goals of this project are tomap the HCN distribution of Comet C2012 F6 (Lemmon) and toshow the simultaneous observation capabilities of the AtacamaLarge MillimeterSubmillimeter Array (ALMA) which allows theextraction of 7-m array 12-m array and single dish observationdata On UT 2013 May 11 Comet Lemmon was observed usingALMA The Cycle 1 configuration was used with the Band 6receivers with a 15 GHz range centered on the HCN transition at26586 GHz which gave a spectral resolution of 007 kms Weshow that Comet Lemmon has both a compact HCN region (foundwith the 12-m array) and also an extended component forming atail-like structure in the anti-motion direction (found with the 7-marray) We were also able to extract the autocorrelation data (singledish) and show that it is viable This project was supported andfunded by NRAO in conjunction with the National ScienceFoundation (NSF) with special thanks to the AstronomyDepartment at University of Virginia

Author(s) Shawn Booth Andrew Burkhardt JoannaCorby Niklaus Dollhopf Mark Rawlings Anthony RemijanInstitution(s) 1 National Radio Astronomy Observatory 2University of Virginia

41524 ndash New Analysis of the Deep Impact Comet9PTempel 1 Event Using High ResolutionSpectroscopy Evidence for High Velocity Long-LivedEmission from 630 nm [O( 1 D)] Emission

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Thorough analysis of narrow bandpass high spectral resolution (Rasymp100000) observations of [O 1 D] 630nm emission from comet9PTempel 1 taken over a ~1rsquo FOV both before and after the DeepImpact event provides evidence for a long-lived high velocityjet-like feature The observations were obtained with anall-reflective spatial heterodyne spectrometer (SHS) coupled to theMcMath-Pierce Main telescope Several spectra centered onTempel 1 were acquired during the period of 07042005-07062005 UT We report here on the presence and evolution of acometary emission feature that appears consistently andexclusively in the post-impact narrow-band spectra centered nearthe telluric [O 1 D] 630nm emission line This cometary emissionfeature shows substantial and distinct Doppler shifts overconsecutive post-impact observational nights and if the feature isthe anticipated [O 1 D] the corresponding line of sight velocitiesare -134 to -65 kms relative to the cometrsquos rest frame

Author(s) Jason B Corliss Walt M Harris Edwin JMierkiewicz Frederick L RoeslerInstitution(s) 1 Embry-Riddle Aeronautical University 2University of Arizona - LPL 3 University of Wisconsin-Madison

41525 ndash Detection of known meteoroid streams usingPan-STARRSMeteors are produced from meteoroids that are Near Earth Objects(NEOs) Created from the disruption of comets and asteroids theirstudy allows for the physical and chemical properties of parentbodies to be better constrained Because most meteoroids are toosmall to be directly observed in space ground-based cameranetworks (such as Weryk et al 2008) are often used to detectfireballs produced from centimetre sized objects and their massinflux can be extrapolated to larger sizesThe masssize distribution of meteoroid streams is an importanttopic relating directly to the impact hazard to the Earth (see Brownet al 2015) Unfortunately the largest meteoroids interact withthe Earthrsquos atmosphere so infrequently that their observation isvery biased and not predictable but due to their large size theymay be visible in space Barabanov and Smirnov (2005) presenteddetections of large possibly cometary meteoroids over 5 m indiameter but their results could not be confirmed by Beech et al(2004) More recently Micheli and Tholen (2015) looked forobjects in the meteoroid streams of several major showers butfound no stream objectsThe Pan-STARRS1 (PS1) telescope operated by the University ofHawai`i has a large seven square degree field-of-view which canreliably detect new NEOs However not every NEO candidate isfollowed up and linked into a well established orbit possibly due tothe fact that the smallest bodies will not be visible at the sensitivitylimit of PS1 for very long or that their predicted orbit is uncertainso follow up telescopes look in the wrong location In this work wepresent our results to date about searching for potential meteoroidstreams (with an emphasis on cometary streams) with the PS1telescope using its multi-year database of unlinked NEOdetections For recent observations where possible we haveobserved the true non-geocentric radiants directly during peakshower activity The detection of known meteoroid streams willallow for additional follow up studies with other telescopes

Author(s) Robert J Weryk Richard J WainscoatInstitution(s) 1 Univ of Hawaii

416 ndash Characterization of Extrasolar Planets41601 ndash The effects of H -He pressure broadeningparameters on the retrieval of brown dwarfatmospheresBrown dwarf atmospheres are compositionally very similar to thegas giant planets made up of approximately 85 H and 15 Heas well as other trace gases such as CH and H O depending onthe spectral type We have investigated the effects of using pressurebroadening parameters related to H -He broadening andcompared them to using air-broadening parameters for each of themajor trace gases involved in brown dwarf atmospheres We have

identified from limited data sets that H -He broadening relative toair broadening can act to increase or decrease the Lorentzianbroadening experienced by a given transition This change inLorentzian broadening is dependent on the gas considered and thetransitions associated quantum numbers (such as rotational andvibrational quantum numbers) By altering the transitionrsquoslineshape we also alter its opacity Some gases are affectedsignificantly at all pressure levels (NH CO CH ) some at deep(~1bar) pressure levels (CO H O) and others not at all (TiO VO)We conclude however that these limited data sets do not providethe complex and comprehensive dependence of pressurebroadening on the relevant quantum numbers that is available toair broadening and we cannot say for certain how much this limitsour results until more data is available Our conclusionsdemonstrate the need for further study of H and He broadeningparameters for the relevant gases from both experimental andcomputational means We present preliminary results of theknock-on effects that these broadening parameters have for theretrieval of atmospheric composition and thermal structure

Author(s) Ryan Garland Patrick G J Irwin SuzanneAigrain Joanna K BarstowInstitution(s) 1 University of Oxford

41602 ndash Spitzer Secondary Eclipse Observations ofHot-Jupiters WASP-26b and CoRoT-1bWASP-26b is a hot-Jupiter planet that orbits an early G star every27566 days at a distance of 003985 AU Using the Spitzer SpaceTelescope in 2010 as a part of the Spitzer Exoplanet Target ofOpportunity program (program 60003) we observed two secondaryeclipses of the planet one in the 36 μm channel on 7 Septemberand one in the 45 μm channel on 3 August We also reanalizearchival Spitzer data of CoRoT-1b which is another hot Jupiterorbiting a G star every 15089686 days at a distance of 00254 AUin the 36 and 45 μm channels The eclipse depths for WASP-26bare 000117 plusmn 000012 and 0001507 plusmn 000016 for the 36 and 45μm channels respectively The eclipse depths for CoRoT-1b are00047 plusmn 00003 and 00046 plusmn 00004 respecitvely We also refinetheir orbits using our own secondary eclipse measurements incombination with external radial-velocity and transit observationsfrom both professional and amateur observers Using our BayesianAtmostpheric Radiative Transfer code we characterize theatmospheres of these planets Spitzer is operated by the JetPropulsion Laboratory California Institute of Technology under acontract with NASA This work was supported by NASA PlanetaryAtmospheres grant NNX12AI69G and NASA Astrophysics DataAnalysis Program grant NNX13AF38G Blecic holds a NASA Earthand Space Science Fellowship

Author(s) Emerson DeLarme Joseph Harrington PatricioCubillos Jasmina Blecic Andrew SD Foster Justin Garland AJFoster Andrew Collier CameronInstitution(s) 1 University of Central Florida 2 University ofSt Andrews

41604 ndash Observation and Analysis of SecondaryEclipses of WASP-32bWe report two Spitzer secondary eclipses of the exoplanetWASP-32b Discovered in 2010 by Maxted et al this hot-Jupiterplanet has a mass of 36 plusmn 007 M a radius of 118 plusmn 007 R anequilibrium temperature of 1560 plusmn 50 K and an orbital period of271865 plusmn 000008 days around a G-type star We observed twosecondary eclipses in the 36 microm and 45 microm channels using theSpitzer Space Telescope in 2010 as a part of the Spitzer ExoplanetTarget of Opportunity program (program 60003) We presenteclipse depth estimates of 00013 plusmn 000023 in the 45 microm bandand inconclusive results in the 36 microm band We also report aninfrared brightness temperature of 1538 plusmn 110 in the 45 micromchannel and refinements of orbital parameters for WASP-32b fromour eclipse measurement as well as amatuer and professional datathat closely match previous results Spitzer is operated by the JetPropulsion Laboratory California Institute of Technology under acontract with NASA This work was supported by NASA PlanetaryAtmospheres grant NNX12AI69G and NASA Astrophysics Data

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Analysis Program grant NNX13AF38G JB holds a NASA Earth andSpace Science Fellowship

Author(s) Justin Garland Joseph Harrington Patricio ECubillos Jasmina Blecic Andrew S Foster Oliver Bowman Pierre F L MaxtedInstitution(s) 1 University of Central Florida 2 University ofKeele

41605 ndash Secondary eclipse observations and theatmosphere of exoplanet WASP-34bWASP-34b is a short-period exoplanet with a mass of 059 plusmn 001Jupiter masses orbiting a G5 star with a period of 43177 days andan eccentricity of 0038 plusmn 0012 (Smalley 2010) We observedWASP-34b using the 36 and 45 μm channels of the Infrared ArrayCamera aboard the Spitzer Space Telescope in 2010 (Program60003) We applied our Photometry for Orbits Eclipses andTransits (POET) code to present eclipse-depth measurementsestimates of infrared brightness temperatures and a refined orbitWith our Bayesian Atmospheric Radiative Transfer (BART) codewe characterized the atmospheres temperature and pressureprofile and molecular abundances Spitzer is operated by the JetPropulsion Laboratory California Institute of Technology under acontract with NASA This work was supported by NASA PlanetaryAtmospheres grant NNX12AI69G and NASA Astrophysics DataAnalysis Program grant NNX13AF38G J Blecic holds a NASAEarth and Space Science Fellowship

Author(s) Ryan C Challener Joseph Harrington PatricioCubillos Justin Garland Andrew S D Foster Jasmina Blecic AJ Foster Barry SmalleyInstitution(s) 1 Keele University 2 University of CentralFlorida

41606 ndash Atmospheric Orbital and Eclipse DepthAnalysis of the Hot Jupiter HAT-P-30-WASP-51bHAT-P-30-WASP-51b is a hot-Jupiter planet that orbits an F starevery 28106 days at a distance of 00419 AU Using the SpitzerSpace Telescope in 2012 (Spitzer Program Number 70084) weobserved two secondary eclipses of the planet one in the 36 μmchannel on 3 January and one in the 45 μm channel on 17January We present eclipse-depth measurements of 000163 plusmn00001 and 000146 plusmn 000013 and we esitmate the infraredbrightness temperatures to be 1900 plusmn 50 and 1600 plusmn 60 for thesetwo channels respectively from an analysis using our Photometryfor Orbits Eclipses and Transits (POET) pipeline We also refineits orbit using our own secondary-eclipse measurements incombination with radial-velocity and transit observations fromboth professional and amateur observers The most notable resultfrom this orbital analysis is a detection of eccentricity in theplanets orbit Using only the phase of our secondary eclipses wecan constrain ecosw to a minimum of 00084 plusmn 00004 a 20 sigmadetection of one component of the orbits eccentricity that isindependent of the effects that stellar tides have on radial velocitydata We then characterize its atmospheres temperature- pressureprofile and molecular abundances using our Bayesian AtmosphericRadiative Transfer code (BART) Spitzer is operated by the JetPropulsion Laboratory California Institute of Technology under acontract with NASA This work was supported by NASA PlanetaryAtmospheres grant NNX12AI69G and NASA Astrophysics DataAnalysis Program grant NNX13AF38G J Blecic holds a NASAEarth and Space Science Fellowship

Author(s) Andrew S Foster Joseph Harrington PatricioCubillos Jasmina Blecic A J Foster Ryan Challener JustinGarlandInstitution(s) 1 University of Central Florida

41607 ndash Chemical uncertainties in modeling hotJupiters atmospheresMost predictions and interpretations of observations in beyond ourSolar System have occurred through the use of 1D photo-thermo-chemical models Their predicted atmospheric compositions arehighly dependent on model parameters Chemical reactions are

based on empirical parameters that must be known attemperatures ranging from 100 K to above 2500 K and at pressuresfrom millibars to hundreds of bars Obtained from experimentscalculations and educated-guessed estimations these parametersare always evaluated with substantial uncertainties Howeveralthough of practical use few models of exoplanetary atmosphereshave considered these underlying chemical uncertainties and theirconsequences Recent progress has been made recently that allowus to (1) evaluate the accuracy and precision of 1D models ofplanetary atmospheres with quantifiable uncertainties on theirpredictions for the atmospheric composition and associatedspectral features (2) identify the lsquokey parametersrsquo that contributethe most to the models predictivity and should therefore requirefurther experimental or theoretical analysis (3) reduce andoptimize complex chemical networks for their inclusion inmultidimensional atmospheric modelsFirst a global sampling approach based on low discrepancysequences has been applied in order to propose error bars onsimulations of the atmospheres HD 209458b and HD 189733busing a detailed kinetic model derived from applied combustionmodels that was methodically validated over a range oftemperatures and pressures typical for these hot Jupiters Atwo-parameters temperature-dependent uncertainty factor hasbeen assigned to each considered rate constant Second a globalsensitivity approach based on high dimensional modelrepresentations (HDMR) has been applied in order to identifythose reactions which make the largest contributions to the overalluncertainty of the simulated results The HDMR analysis has beenrestricted to the most important reactions based on a non-linearscreening method using Spearman Rank Correlation Coefficientsat different level of the modeled atmospheres The individualcontributions of some key reactions as highlighted by this analysiswill be discussed

Author(s) Eric Hebrard Shawn Domagal-GoldmanInstitution(s) 1 NASA Goddard Space Flight Center

41608 ndash On the parameterization of 1D verticalmixing in planetary atmospheres insights from 2Dand 3D simulationsMost of the current atmospheric chemistry models for planets (egKrasnopolsky amp Parshev 1981 Yung amp Demore 1982 Yung Allenamp Pinto 1984 Lavvas et al 2008 Zhang et al 2012) and exoplanets(eg Line Liang amp Yung 2010 Moses et al 2011 Hu amp Seager2014) adopt a one-dimensional (1D) chemical-diffusion approachin the vertical coordinate Although only a crude approximationthese 1D models have succeeded in explaining the global-averagedvertical profiles of many chemical species in observations One ofthe important assumptions of these models is that all chemicalspecies are transported via the same eddy diffusion profile--that isthe assumption is made that the eddy diffusivity is a fundamentalproperty of the dynamics alone and does not depend on thechemistry Here we show that as also noticed in the Earthcommunity (eg Holton 1986) this ldquohomogenous eddy diffusionrdquoassumption generally breaks down We first show analytically whythe 1D eddy diffusivity must generally depend both on thehorizontal eddy mixing and the chemical lifetime of the speciesThis implies that the long-lived species and short-lived chemicalspecies will generally exhibit different eddy diffusion profiles evenin a given atmosphere with identical dynamics Next we presenttracer-transport simulations in a 2D chemical-diffusion-advectionmodel (Shia et al 1989 Zhang Shia amp Yung 2013) and a 3Dgeneral circulation model (MITgcm eg Liu amp Showman 2013)for both rapid-rotating planets and tidally-locked exoplanets tofurther explore the effect of chemical timescales on the eddydiffusivity From the 2D and 3D simulation outputs we deriveeffective 1D eddy diffusivity profiles for chemical tracers exhibitinga range of chemical timescales We show that the derived eddydiffusivity can depend strongly on the horizontal eddy mixing andchemistry although the dependences are more complex than theanalytic model predicts Overall these results suggest that cautionis warranted when using 1D models with multiple species mixed bya single eddy diffusivity profile Possible consequences will bediscussed

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Author(s) Xi Zhang Adam P ShowmanInstitution(s) 1 University of Arizona 2 University ofCalifornia Santa Cruz

41609 ndash Atmospheres of partially differentiatedsuper-Earth exoplanetsTerrestrial exoplanets have been discovered in a range of sizesdensities and orbital locations that defy our expectations basedupon the Solar System Planets discovered to date with radii lessthan ~15-16 Earth radii all seem to fall on an iso-density curvewith the Earth [1] However mass and radius determinationswhich depend on the known properties of the host star are notaccurate enough to distinguish between a fully differentiatedthree-layer planet (core mantle oceanatmosphere) and anincompletely differentiated planet [2] Full differentiation of aplanet will depend upon the conditions at the time of accretionincluding the abundance of short-lived radioisotopes which willvary from system to system as well as the number of giant impactsthe planet experiences Furthermore separation of metal andsilicates at the much larger pressures found inside super-Earthswill depend on how the chemistry of these materials change at highpressures There are therefore hints emerging that not all super-Earths will be fully differentiated Incomplete differentiation willresult in a more reduced mantle oxidation state and may haveimplications for the composition of an outgassed atmosphere Herewe will present the first results from a chemical equilibrium modelof the composition of such an outgassed atmosphere and discussthe possibility of distinguishing between fully and incompletelydifferentiated planets through atmospheric observations[1] Rogers L 2015 ApJ 801 41 [2] Zeng L amp Sasselov D 2013PASP 125 227

Author(s) Laura Schaefer Dimitar SasselovInstitution(s) 1 Harvard University

41610 ndash A Novel Approach to Atmospheric Retrievalfor Small ExoplanetsRetrieval of environmental parameters from the spectra ofsub-Neptune and terrestrial extrasolar planets is extremelychallenging due to the observational difficulty the inherentcomplexity of planetary processes and the likely diversity ofenvironments for these small objects The best retrieval techniqueswill use observations of the star-planet system along withknowledge of planetary processes gleaned from objects in the SolarSystem to constrain retrieved environmental parametersWe present ongoing work of the Virtual Planetary Laboratory(VPL) to develop a versatile terrestrial atmosphere retrieval suitecapable of capturing a wide range of terrestrial planet processeswhile employing robust statistics Our novel approach is to producefits to observed spectra that discriminate between degeneratesolutions by considering limitations on planetary environmentsderived from known physics and chemistry The forward modelleverages the SMART 1-D line-by-line fully multiple-scattering andwidely validated radiative transfer model (Meadows amp Crisp 1996)as the primary workhorse for computing transit transmissionthermal emission and reflectance spectroscopy Following theapproach of the CHIMERA code (Line et al 2013 2014) we employa variety of inverse models for the problem of parameterestimation Here we present preliminary results using optimalestimation for terrestrial and sub-Neptune planets The model isbeing validated against synthetic Solar System and existingexoplanet observationsThis model will be used to explore the capabilities of key telescopearchitectures to understand information loss when planets areviewed as a point source and to provide a data analysis frameworkfor future sub-Neptune super-Earth and Earth analog exoplanetobservations

Author(s) Jacob Lustig-Yaeger Victoria Meadows MichaelLine David CrispInstitution(s) 1 Jet Propulsion Laboratory California Instituteof Technology 2 University of California Santa Cruz 3University of Washington

41611 ndash A study of temporal variability of clouds inexo-atmospheres using Earth observations as a proxyClouds are strongly linked to the dynamics of the atmosphere andhave been observed to vary over multiple spatial scales andtimescales on Earth and the planets hourly diurnal seasonalinterannual and decadal The study of such variations inexoplanetary atmospheres could only be made through lightlyconstrained general circulation models (GCMs) In most cases theexoplanet itself is unresolved from its star and individual cloudpatches and their variations cannot be observed Howevertemporal and spatial variation of cloud fields can have significantimplications for the interpreting the observed phase-curve of thelights from the star-exoplanet system yet it remains almost whollyunconstrained To address this issue we model Earth as anexoplanet to understand changes in observables due to temporaland spatial variations of clouds by leveraging the rich datasetsavailable for Earth In particular the International Satellite CloudClimatology Project (ISCCP) has compiled cloud observations onEarth in the past three decades producing a high-resolutiondataset We perform radiative transfer calculations using cloudprofiles sampled from this dataset to produce disc integratedbrightness and polarization phase curves which map seasonal andinterannual cloud variations This exercise gives us the first(pseudo)-observation based constraints for temporal variability ofclouds in exo-atmospheres

Author(s) Pushkar Kopparla Albert Zhai Alice Zhai HuiSu Jonathan H Jiang Yuk Ling YungInstitution(s) 1 California Institute of Technology 2 JetPropulsion Laboratory

41612 ndash Atmospheric Ozone Formation andObservation Effects on Waterless Rocky Exoplanetsaround M DwarfsIt is recently proposed that up to two thousand bars of Oatmospheres could buildup on rocky planets near M dwarfs as theresult of stellar luminosity evolution and runaway water loss(Luger and Barnes 2015) Here we use a one-dimensionalphotochemical model to study ozone distributions in thesehypothetical O -rich atmospheres Our study showed that ozonelayers in denser O atmospheres locate at higher altitudes than thatin the Earthrsquos atmospheres A higher ozone layer should generatestronger O absorption feature potentially different from that ofour Earth We also present the enhancement of transmissionspectral features which could be useful to identify such denseO -rich atmospheres by future exoplanet characterization missionsand facilities such as JWST

Author(s) Chuhong Mai Feng TianInstitution(s) 1 Center for Earth System Sciences TsinghuaUniversity 2 School of Earth and Space Exploration ArizonaState University

41613 ndash HSTWFC3 Updates Impacting ExoplanetObserversWe provide a summary of new Wide Field Camera 3 (WFC3)capabilities and updates to the Hubble Space Telescope (HST)proposal process of interest to exoplanet observers In particularwe discuss recent studies on high precision photometry with spatialscanning that show up to 01 photometric repeatability for theUVIS channel and 05 for the IR channel We describe a new IRsample sequence spars5 which may open up more orient rangesand scheduling opportunities for exoplanet targets Finally wepresent a new mid-cycle proposal scheme for HST that will allowobservers to apply for up to 5 orbits outside the standard annualcall for proposals this will be especially advantageous for observersof recently discovered exoplanets

Author(s) Catherine Gosmeyer Peter R McCullough Sylvia Baggett Elena SabbiInstitution(s) 1 Space Telescope Science Institute

41614 ndash Forward Models of Exoplanets forAtmosphere Retrievals with JWST

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We present models of extrasolar planets focusing on super-Earthsand mini-Neptunes and incorporating self-consistent treatment ofinternal structures radiative cooling and XUV-driven mass lossover time and atmosphere models with 1-D radiative transfer and arange of compositions and cloud structures These models aredesigned for performing retrievals of atmosphere parameters withdata from the upcoming JWST mission

Author(s) Alex Howe Adam BurrowsInstitution(s) 1 Princeton University

41615 ndash 3D modeling of clouds in GJ1214bsatmosphereGJ1214b is a warm mini-Neptunewaterworld and one of the fewlow-mass exoplanets whose atmosphere is characterizable bycurrent telescopes Recent observations indicated a flat transitspectrum in near-infrared which has been interpreted as thepresence of high and thick condensate clouds of KCl or ZnS orphotochemical hazes However the formation of such highcloudshazes would require a strong vertical mixing linked to theatmospheric circulation In order to understand the transportdistribution and observational implications of such cloudshazewe studied the atmospheric circulation and cloud formation onGJ1214b for H-dominated and water-dominated atmospheresusing the Generic LMDZ GCMFirstly we analyzed cloud-free atmospheres We showed that thezonal mean meridional circulation corresponds to an anti-Hadleycirculation in most of the atmosphere with upwelling at midlatitudeand downwelling at the equator This circulation should stronglyimpact cloud formation and distribution leading to a minimum ofcloud at the equator We also derived 1D equivalent eddy diffusioncoefficients The corresponding values should favor an efficientformation of photochemical haze in the upper atmosphere ofGJ1214bSecondly we simulated cloudy atmospheres including latent heatrelease and radiative effects for KCl and ZnS clouds We analyzedtheir impacts on the thermal structure In particular we fund thatZnS clouds may lead to the formation of a stratospheric thermalinversion We showed that flat transit spectra consistent with HSTobservations are possible for cloud particle radii around 05microns Using the outputs of our GCM we also generatedemission and reflection spectra and phases curvesFinally our results suggest that primary and secondary eclipsesand phase curves observed by JWST should provide strongconstraints on the nature of GJ1214bs atmosphere and clouds

Author(s) Benjamin Charnay Victoria Meadows Jeacutereacutemyleconte Amit Misra Giada ArneyInstitution(s) 1 LMD 2 University of Washington

41616 ndash Polarisation of Planets and ExoplanetsWe present observations of the linear polarisation of several hotJupiter systems with our new high-precision polarimeter HIPPI(HIgh Precision Polarimetric Instrument) By looking at thecombined light of the star and planet we aim to detect the polarisedlight reflected from the planets atmosphere This can provideinformation on the presence of and nature of clouds in theatmosphere and constrain the geometric albedo of the planet Themethod is applicable to both transitting and non-transittingplanets and can also be used to determine the inclination of thesystem and thus the true mass for radial velocity detected planetsTo predict and interpret the polarisation from such observationswe have also developed an advanced polarimetric modellingcapability by incoroporating full polarised radiative transfer intoour atmospheric modelling code VSTAR This is done using theVLIDORT vector radiative transfer solver (Spurr 2006) Theresulting code allows us to predict disc-resolved phase-resolvedand spectrally-resolved intensity and linear polarisation for anyplanet exoplanet brown dwarf or cool star atmosphere that can bemodelled with VSTAR We have tested the code by reproducingbenchmark calculations in polarised radiative transfer and by SolarSystem test cases including reproducing the classic Hansen andHovenier (1974) calculation of the polarisation phase curves ofVenus

Hansen JE amp Hovenier JW 1974 J Atmos Sci 31 1137Spurr R 2006 JQSRT 102 316

Author(s) Jeremy Bailey Lucyna Kedziora-Chudczer Kimberly Bott Daniel V CottonInstitution(s) 1 University of New South Wales

41617 ndash Constraining the Structure of Hot JupiterAtmospheres Using a Hybrid Version of the NEMESISRetrieval AlgorithmUnderstanding the formation environments and evolutionscenarios of planets in nearby planetary systems requires robustmeasures for constraining their atmospheric physical propertiesHere we have utilized a combination of two different parameterretrieval approaches Optimal Estimation and Markov Chain MonteCarlo as part of the well-validated NEMESIS atmospheric retrievalcode to infer a range of temperature profiles and molecularabundances of H O CO CH and CO from available daysidethermal emission observations of several hot-Jupiter candidatesIn order to keep the number of parameters low and henceforthretrieve more plausible profile shapes we have used a parametrizedform of the temperature profile based upon an analytic radiativeequilibrium derivation in Guillot et al 2010 (Line et al 20122014) We show retrieval results on published spectroscopic andphotometric data from both the Hubble Space Telescope andSpitzer missions and compare them with simulations from theupcoming JWST mission In addition since NEMESIS utilizescorrelated distribution of absorption coefficients (k-distribution)amongst atmospheric layers to compute these models updates tospectroscopic databases can impact retrievals quite significantly forsuch high-temperature atmospheres As high-temperature linedatabases are continually being improved we also compareretrievals between old and newer databases

Author(s) Mahmuda A Badhan Avi M Mandell BrigetteHesman Conor Nixon Drake Deming Patrick Irwin JoannaBarstow Ryan GarlandInstitution(s) 1 NASA Goddard Space Flight Center 2University of Maryland 3 University of Oxford

41618 ndash Photochemical hazes in planetaryatmospheres solar system bodies and beyondRecent transit observations of exoplanets have demonstrated thepossibility of a wide prevalence of hazecloud layers at highaltitudes Hydrocarbon photochemical haze could be the candidatefor such haze particles on warm sub-Neptunes but the lack ofevidence for methane poses a puzzle for such hydrocarbonphotochemical haze The CH CO ratios in planetary atmospheresvary substantially from their temperature and dynamics Anunderstanding of haze formation rates and plausible opticalproperties in a wide diversity of planetary atmospheres is requiredto interpret the current and future observations

Here we focus on how atmospheric compositions specificallyCH CO ratios affect the haze production rates and their opticalproperties We have conducted a series of cold plasma experimentsto constrain the haze mass production rates from gas mixtures ofvarious CH CO ratios diluted either in H or N atmosphere Themass production rates in the N -CH -CO system are much greaterthan those in the H -CH -CO system They are rather insensitiveto the CH CO ratios larger than at 03 Significant formation ofsolid material is observed both in H -CO and N -CO systemswithout CH4 in the initial gas mixtures The complex refractiveindices were derived for haze samples from N -CH H -CH andH -CO gas mixtures These are the model atmospheres for TitanSaturn and exoplanets respectively The imaginary part of thecomplex refractive indices in the UV-Vis region are distinct amongthese samples which can be utilized for modeling these planetaryatmospheres

Author(s) Hiroshi Imanaka Dale P Cruikshank Christopher P McKayInstitution(s) 1 NASA Ames Research Center 2 SETI Institute

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41619 ndash The HSTSTIS BAR5 Occulter High Contrastin Space at Visible WavelengthsThe Hubble Space Telescope currently has only one operationalhigh contrast imaging coronagraphic mode the 50CORON imagingmode of the Space Telescope Imaging Spectrograph (STIS)50CORON includes two intersecting wedges and two bar occultingmasks in an image plane ahead of the detector that block light frombright stars to reveal the faint emission from circumstellar disks orfaint companions Recently the smallest supported inner workingangle for these occulters was 03 We present in this poster thecommissioning of new occulting locations on the detector thatallow for inner working angles as close as 015 at the new BAR5position We show preliminary results for BAR5 using two nearbydebris disks AU Mic and Beta Pictoris and provide interested userswith a prescription for how to design their own high contrastimaging observations

Author(s) John H Debes Andras Gaspar GlennSchneider Charles ProffittInstitution(s) 1 STScI 2 The University of Arizona

41620 ndash ARIEL Atmospheric Remote-SensingInfrared Exoplanet Large-surveyMore than 1000 extrasolar systems have been discovered hostingnearly 2000 exoplanets Ongoing and planned ESA and NASAmissions from space such as GAIA Cheops PLATO K2 and TESSwill increase the number of known systems to tens of thousandsOf all these exoplanets we know very little ie their orbital dataand for some of these their physical parameters such as their sizeand mass In the past decade pioneering results have beenobtained using transit spectroscopy with Hubble Spitzer andground-based facilities enabling the detection of a few of the mostabundant ionic atomic and molecular species and to constrain theplanetrsquos thermal structure Future general purpose facilities withlarge collecting areas will allow the acquisition of better exoplanetspectra compared to the currently available especially from faintertargets A few tens of planets will be observed with JWST andE-ELT in great detailA breakthrough in our understanding of planet formation andevolution mechanisms will only happen through the observation ofthe planetary bulk and atmospheric composition of a statisticallylarge sample of planets This requires conducting spectroscopicobservations covering simultaneously a broad spectral region fromthe visible to the mid-IR It also requires a dedicated space missionwith the necessary photometric stability to perform thesechallenging measurements and sufficient agility to observemultiple times ~500 exoplanets over mission life-timeThe ESA-M4 mission candidate ARIEL is designed to accomplishthis goal and will provide a complete statistically significant sampleof gas-giants Neptunes and super-Earths with temperatures hotterthan 600K as these types of planets will allow direct observation oftheir bulk properties enabling us to constrain models of planetformation and evolutionThe ARIEL consortium currently includes academic institutes andindustry from eleven countries in Europe the consortium is openand invites new contributions and collaborations

Author(s) Giovanna TinettiInstitution(s) 1 University College London

417 ndash Discoveries and Dynamics ofExtrasolar Planets41701 ndash The NASA Exoplanet ArchiveThe NASA Exoplanet Archive is an online astronomical exoplanetand stellar catalog and data service that collates and cross-correlates astronomical data on exoplanets and their host stars andprovides tools to work with these data The Exoplanet Archive isdedicated to collecting and serving important public data setsinvolved in the search for and characterization of extrasolar planetsand their host stars The data include stellar parameters exoplanet

parameters and discoverycharacterization data from theastronomical literature The Archive also hosts mission and surveydata including Kepler pipeline data such as candidate lists and datavalidation products and ground-based surveys from SuperWASPand KELT Tools provided for users to work with these data includea transit ephemeris predictor light curve viewing utilities and aperiodogram service

Author(s) Rachel L AkesonInstitution(s) 1 NASA Exoplanet Science Institute Caltech

41702 ndash PICK2 Planets in Clusters with K2Open clusters are remarkable laboratories for a wide variety ofastrophysical investigations They comprise the mosthomogeneous samples of stars that we can ever hope to find Theyare stars that share the same age initial chemical compositiondistance and dynamical environment The fundamental propertythat distinguishes one star from another in a cluster is simply thestellar mass This gives us the very rare opportunity to conduct wellcontrolled astrophysical studies of stars and as a result there is avast astronomical literature focused on understanding andcharacterizing the members of stellar clustersWe are searching for transiting planets in five open clusters in theNASA K2 mission Fields 4 5 and 7 These clusters range in agefrom 125My (Pleiades) through the 625My ages of the Hyades andPraesepe up to the much older Ruprecht 147 (25 Gyr) and M67(3-5 Gyr) clusters Examination of the distribution of planetaryorbital parameters as well as the planetary multiplicity radius andmass distributions as a function of stellar age (and in comparisonwith field stars from both K2 and Kepler) will provide a powerfultest of theories of planetary system formation and dynamicalevolution The radii of hot Jupiters and Saturns as a function ofcluster age will provide a sensitive test of theories to explain thepopulation of inflated hot JupitersOur team will process the K2 pixel files into light curves for eachtarget star and will then search these light curves for possibleplanet transit events We will apply standard vetting procedures toremove likely false-positives and we will then model the transitprofiles We will then conduct an extensive set of ground-basedfollow-up observations using a wide range of observationalfacilities at our disposal These will include imaging highresolution visible and near-IR spectroscopy precise radial velocitymeasurement and ground-based observations of further transitsas appropriate

Author(s) William D Cochran Michael Endl Marshall CJohnson Byeong-Cheol Lee Chan Park Inwoo Han HeikeRauer Juan Cabrera Szilard Csizmadia Martin Paetzold David Yong Martin Asplund Artie P HatzesInstitution(s) 1 Aust Nat Univ 2 DLR 3 KASI 4 TLSTautenburg 5 Univ Koumlln 6 Univ of Texas Austin

41703 ndash An Exo-Venus Around a Cool Nearby StarWe present the discovery and planetary confirmation of KOI-3138a likely Earth-sized (108 Earth radii ) planet in a 9-day orbitaround a nearby M Dwarf star A planet transit was detected aroundKOI-3138 with the Kepler spacecraft and confirmed via falsepositive analysis using data from the UK Infrared telescope DigitalSky Survey and DSSI Speckle imaging The planetrsquos short orbitalperiod places it close to its host star making it an interesting Venusanalog around a cool starIt remains possible although unlikely that KOI-313801 insteadorbits a bound undetected binary companion to KOI-3138 Underthese conditions the planet becomes a mini-Neptune-sized planetorbiting a brown dwarf with a mass of ~005 solar mass Follow-upradial velocity measurements on the host star are required in orderto accurately assess the likelihood of this possibility Specificallydetection of a significant radial velocity ( ~725 ms) uponobservation of KOI-3138 will indicate the presence of a boundcompanion that was not detected by our false positive analysisprocedures Such a companion if detected cannot be ruled out asthe host star around which KOI-313801 orbitsKOI-313801 is too small to induce a detectable ldquowobble in its host

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star We therefore make no conclusions about mass orcomposition However there is reasonable incentive to determinethese properties in the hopes of understanding the nature ofhabitable zones around M-type stars Kepler-186f a previouslydiscovered Earth-like exoplanet is similar in size to KOI-313801and orbits the outer reaches of its starrsquos conservative habitablezone KOI-313801 also Earth-sized orbits a similar star butresides much closer in The two planets together span the range ofdistances within the habitable zones of M Dwarfs Determining thecomposition and atmosphere of KOI-313801 is therefore useful inunderstanding the nature of habitable zone boundaries of such startypes This task may in fact be possible with the James Webb SpaceTelescope (JWST) which will characterize atmosphericcompositions of nearby Earth-sized planets like KOI-313801 andthereby provide insight into the habitability of both known andto-be-discovered exoplanets

Author(s) Isabel Angelo Jason F Rowe Steve B HowellInstitution(s) 1 NASA Ames Research Center 2 UC Berkeley

41704 ndash Connections among spacing compositionand flatness in super-Earth systemsThe collection of thousands of super-Earths discovered by theKepler Mission contains a wealth of information about the processof planet formation Their spacing distribution is an archaeologicalartifact of the final stages of planet formation when planets growfrom embryos to super-Earths We explore how the interplaybetween stirring and mergers establishes the spacing distributionand links it to the composition and flatness of planets in thesystem with the latter influenced by damping by residual gas Weshow how these links manifest in Kepler observables such asperiod ratio number of transiting planets and transit durationratios Our study theoretically motivates connections betweenarchitectures and compositions that reflect conditions during theend stages of planet formation and are not merely the result ofselection effects

Author(s) Rebekah Ilene Dawson Eve J Lee EugeneChiangInstitution(s) 1 University of California Berkeley

41705 ndash Spin-Orbit Misalignment of Two-Planet-System KOI-89 via Gravity DarkeningWe investigate the causes of spin-orbit misalignment in exoplanetsystems via two-planet-system KOI-89 This system is of particularinterest because it can experimentally constrain the numerousoutstanding hypotheses that have been proposed to generatemisalignments We constrain both the spin-orbit angles and therelative alignment between the planes of the two orbits usinggravity darkening By fitting KOI-89s 17 long cadence quarters ofKepler photometry we show that the 85-day-orbit and208-day-orbit planets are misaligned from the host stars rotationaxis by 72deg plusmn 3deg and 73deg (+11deg -5deg) respectively From theseresults we limit KOI-89s causes of spin-orbit misalignment basedon three criteria agreement with KOI-89s fundamentalparameters the capability to cause extreme misalignment andconformance with mutually aligned planets We limit likely causesto star-disk binary interactions disk warping via planet-diskinteractions Kozai resonance planet-planet scattering or internalgravity waves in the convective interior of the star Our resultsdisfavor planet-embryo collisions chaotic evolution of stellar spinmagnetic torquing coplanar high-eccentricity migration andinclination resonance

Author(s) Johnathon Ahlers Jason W Barnes RoryBarnesInstitution(s) 1 University of Idaho 2 University ofWashingon

41706 ndash Predicting Precession Rates from SecularDynamics for Extra-solar Multi-planet SystemsConsidering the secular dynamics of multi-planet systems providessubstantial insight into the interactions between planets in thosesystems Secular interactions are those that dont involve knowing

where a planet is along its orbit and they dominate when planetsare not involved in mean motion resonances These interactionsexchange angular momentum among the planets evolving theireccentricities and inclinations To second order in the planetseccentricities and inclinations the eccentricity and inclinationperturbations are decoupled Given the right variable choice therelevant differential equations are linear and thus the eccentricityand inclination behaviors can be described as a sum of eigenmodesSince the underlying structure of the secular eigenmodes can becalculated using only the planets masses and semi-major axes onecan elucidate the eccentricity and inclination behavior of planets inexoplanet systems even without knowing the planets currenteccentricities and inclinations I have calculated both theeccentricity and inclination secular eigenmodes for the populationof known multi-planet systems whose planets have welldetermined masses and periods Using this catalog and assuming aGausian distribution for the eigenmode amplitudes and a uniformdistribution for the eigenmode phases I have predicted what rangeof precession rates the planets may have Generally planets thathave more than one eigenmode significantly contribute to theireccentricity (groupies) can have a wide range of possibleprecession rates while planets that are loners have a narrow rangeof possible precession rates One might have assumed that in anygiven system the planets with shorter periods would have fasterprecession rates However I show that in systems where theplanets suffer strong secular interactions this is not necessarily thecase

Author(s) Christa L Van LaerhovenInstitution(s) 1 Canadian Institute for Theoretical Astrophysics(CITA)

41707 ndash Collisional Cascade in a Debris Disk from anExternal PerturberThe study of circumstellar debris disks has often been coupled withthe study of planet formation A thermally warm debris disk (~300K) may indicate the presence of an exoplanet orbiting within andstirring the disk However there is another possible mechanism forheating a debris disk an external stellar-mass perturber excitingthe eccentricities and inclinations of the particles in a diskWe explore the consequences of an external perturber on theevolution of a debris disk The perturber excites the eccentricities ofthe particles in the disk via the Kozai-Lidov mechanism triggeringa collisional cascade among the planetesimals These collisionsproduce smaller dust grains and damp the particlesrsquo largereccentricitiesWe present the results of our study of a such a disk using secularanalysis and collisional N-body simulations We will discuss theconnections to observations of warm disks and the implications forplanet formation

Author(s) Erika Nesvold Smadar Naoz Laura Vican Benjamin Zuckerman Erika HolmbeckInstitution(s) 1 Department of Physics and Astronomy UCLA2 Department of Physics University of Notre Dame 3Department of Terrestrial Magnetism Carnegie Institution ofWashington

41708 ndash Detection and Characterization of ExtrasolarPlanets through Mean-Motion ResonancesSimulations of Hypothetical Debris DisksA planet orbiting interior or exterior to a debris disk may producesignatures in the disk that reveal the planets presence even if itremains undetected These features appear near mean-motionresonances and provide a powerful tool to not only detect unseenplanets in extra-solar systems but also help constrain their massand orbital parameters I will present results from simulations ofhypothetical debris disks both for interior and exterior resonancesshowing that gaps can be opened in cold debris disks away from theorbit of the planet and thus that not all disk gaps need contain aplanetary body The results allow us to constrain planet massessemi-major axes and eccentricities based on the locations andwidths of the gaps Moreover distinct features likely arising fromLindblad resonances are seen when the planet perturbing the disk

2 1 1

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146

has non-zero orbital eccentricity Finally I will present expressionsthat relate the planetary mass to the widths and locations of theobserved gaps

Author(s) Maryam Tabeshian Paul A WiegertInstitution(s) 1 Department of Physics and AstronomyUniversity of Western Ontario

41709 ndash Planetesimal dispersal during resonantcoupled migration of giant planetsWhen two giant planets during their early phases of evolution aretrapped in a mean motion resonance they may migrate outwardsAlong their path towards the outer regions of the disk they scatteraway most planetesimals within their gravitational reach When thegaseous disk is finally dispersed the leftover planetesimals may notbe numerous enough to break the resonance lock nor to damp apotential eccentricity build-up produced during the coupledmigration phase We performed N-body numerical simulationsshowing that the planetesimal scattering during the coupledoutward migration prevents a pair of planets like Jupiter andSaturn from breaking the 21 resonance once they reach theirpresent location In addition the planet eccentricities forced by theresonance lock remain large and are only slightlydamped before most of the surviving planetesimals are ejectedfrom the system

Author(s) Francesco Marzari Gennaro DAngeloInstitution(s) 1 LANL 2 Univ of Padova

418 ndash Origins of Planetary Systems41801 ndash Pebble Accretion and the Diversity ofPlanetary SystemsUnderstanding how planetary systems form and why they exhibitgreat diversity are key questions in planetary science Recentlyseveral studies of planet formation have focussed on a mechanismcalled ``pebble accretion Here mm-to-m size particles in aprotoplanetary disk are strongly affected by both gas drag andgravity during an encounter with a growing planet This cansubstantially increase the capture probability speeding upplanetary growth and providing a possible solution to thelong-standing problem of how gas-giant planets form within theshort lifetimes of protoplanetary disks (Lambrechts and Johansen2012 Astron Astrophys 544 A32) It has also been suggested thatpebble accretion can explain the profound difference between therocky inner planets and the gas-rich outer planets of the SolarSystem (Morbidelli et al 2015 Icarus 258 418) Here I will presentnew simulations of planet formation in an evolving protoplanetarydisk spanning both the regions in which rocky and gaseous planetsare likely to form The simulations cover the runaway oligarchicand gas-accretion phases of planetary growth and includeapproximate models for pebble growth and the formation ofasteroid sized planetesimals from pebbles Planetary growth ratesin these models are sensitive to the poorly-constrained propertiesof pebbles in a protoplanetary disk and also the properties of thegaseous disk itself especially the strength of turbulence Differentdisk and pebble properties lead to a wide range of outcomesincluding some cases resembling the Solar System and mayexplain the observed diversity of extrasolar planetary systems

Author(s) John E ChambersInstitution(s) 1 Carnegie Inst of Washington

41802 ndash Planetesimals embedded in a gaseous disc vsmean-motion resonancesWe study orbital evolution of km-sized planetesimals in a gaseousdisc with one or more embedded giant protoplanets Especially wefocus on the regions intersected by the inner mean-motionresonances with the innermost (Jovian) protoplanet eg 21 5283 31 The planetesimals orbiting in these regions are subject tocombined effects of aerodynamic and resonant perturbations Weaim to numerically investigate two possible outcomes of thisinterplay First stable resonant islands can exist (as in Chrenko et

al 2015) and may slow down or capture planetesimals as theyspiral sunward In such a case the resonances might serve asnatural barriers for the flux of planetesimals and locally acceleratethe accumulation of the solid materialSecond the resonances can overcome the damping effects of thegas and pump the eccentricities of the crossing planetesimals(Marzari amp Weidenschilling 2002) This process might generateeccentric orbits which lead to increased relative velocities withrespect to the nebular gas and crossing of non-resonant (circular)orbits The environment of the gaseous disc is simulated with theFARGO code (Masset 2000) which is a 2D Eulerian solver of thefluid equations with fast azimuthal advection We modified thecode so it can treat small planetesimals as test particles affected bythe respective aerodynamic dragAcknowledgements The work of OC and MB has been supportedby Charles University in Prague project GA UK No 1062214

Author(s) Ondrej Chrenko Miroslav BrozInstitution(s) 1 Institute of Astronomy Charles University inPrague

41803 ndash The Fragility of the Terrestrial PlanetsDuring a Giant Planet InstabilityMany features of the outer solar system are replicated in numericalsimulations if the giant planets undergo an orbital instability thatejects one or more ice giants During this instability the orbits ofJupiter and Saturn are believed to diverge crossing their 21 meanmotion resonance (MMR) and this resonance-crossing can excitethe orbits of the terrestrial planets Using a large ensemble ofnumerical simulations of this giant planet instability we directlymodel the evolution of the terrestrial planet orbits during thisprocess paying special attention to those systems that reproducethe basic features of the outer planets In systems that retain fourgiant planets and finish with Jupiter and Saturn beyond their 21MMR we find an 80-90 probability that at least one terrestrialplanet is lost Moreover most systems that manage to retain allfour terrestrial planets finish with terrestrial planet eccentricitiesand inclinations larger than the observed ones There is less than a20 chance that the terrestrial planet orbits will have a level ofexcitation comparable to the observed orbits If we factor in theprobability that the outer planetary orbits are well-replicated wefind a probability of 3 or less that the orbital architecture of theinner and outer planets are simultaneously reproduced in the samesystem These small probabilities raise the prospect that the giantplanet instability may have occurred before the terrestrial planetshad formed Such a scenario implies that the giant planet instabilityis not the source of the Late Heavy Bombardment and that theterrestrial planets completed their formation within the giantplanetsrsquo post-instability configuration

Author(s) Nathan A Kaib John E ChambersInstitution(s) 1 Carnegie Institution for Science 2 Universityof Oklahoma

41804 ndash On the Origin of the Kepler-36 SystemThe Kepler-36 system comprises two exoplanets an innerterrestrial super-Earth (45 M ) and an outer gaseoussub-Neptune (81 M ) Both planets are orbiting very close to theirhost star (012 and 013 AU away) and to each other Their orbitalperiods are in nearly a 76 ratio a mean-motion resonance that isnot usually populated Finally the inner planet is much denserthan Earth (75 gcm ) while the outer planet is substantially lessdense (089 gcm ) a surprise given the close proximity of theirorbitsWe examine origin scenarios for Kepler-36 featuring planetarymigration due to dissipative forces within the circumstellar gasdisk In our model the planets did not form in situ but rathermoved inwards through a region of smaller planetesimals andembryos We assume that the outer body formed beyond the frostline with significant gas accretion to account for its low densityThis sub-Neptune migrated inward and captured an embryo ofnegligible relative mass into a 21 orbital resonance Collisionsbetween this embryo and other bodies of similar mass broke theresonance and allowed the two planets to converge while the inner

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one grew in mass and densityUsing HNDrag an N-body code we have found several scenariosthat might explain the observations Although our successfulscenarios occur with low probability this is actually a strength sincefew known systems share the peculiarities of Kepler-36 Our modelexplains the main observed features of this system in the context ofstandard planetary formation theory

Author(s) Thomas Rimlinger Douglas Hamilton DerekRichardsonInstitution(s) 1 University of MD College Park

41805 ndash KOI2138 -- a Spin-Orbit Aligned IntermediatePeriod Super-EarthA planets formation and evolution are encoded in spin-orbitalignment -- the planets inclination relative to its stars equatorialplane While the solar systems spin-orbit aligned planets indicateour own relatively quiescent history many close-in giant planetsshow significant misalignment Some planets even orbitretrograde Hot Jupiters then have experienced fundamentallydifferent histories than we experienced here in the solar system Inthis presentation I will show a new determination of the spin-orbitalignment of 21 R exoplanet candidate KOI2138 KOI2138shows a gravity-darkened transit lightcurve that is consistent withspin-orbit alignment This measurement is important because theonly other super-Earth with an alignment determination (55 Cnc eorbit period 074 days) is misaligned With an orbital period of2355 days KOI2138 is far enough from its star to avoid tidal orbitevolution Therefore its orbit is likely primordial and hence it mayrepresent the tip of an iceberg of terrestrial spin-orbit alignedplanets that have histories that more closely resemble that of thesolar systems terrestrial planets

Author(s) Jason W BarnesInstitution(s) 1 University of Idaho

41806 ndash Sustained Accretion on Gas GiantsSurrounded by Low-Turbulence CircumplanetaryDisksGas giants more massive than Saturn acquire most of theirenvelope while surrounded by a circumplanetary disk (CPD) whichextends over a fraction of the planetrsquos Hill radius Akin tocircumstellar disks CPDs may be subject to MRI-driven turbulenceand contain low-turbulence regions ie dead zones It wassuggested that CPDs may inhibit sustained gas accretion thuslimiting planet growth because gas transport through a CPD maybe severely reduced by a dead zone a consequence at odds with thepresence of Jupiter-mass (and larger) planets We studied how anextended dead zone influences gas accretion on a Jupiter-massplanet using global 3D hydrodynamics calculations with meshrefinements The accretion flow from the circumstellar disk to theCPD is resolved locally at the length scale Rj Jupiters radius Thegas kinematic viscosity is assumed to be constant and the deadzone around the planet is modeled as a region of much lowerviscosity extending from ~Rj out to ~60Rj and off the mid-planefor a few CPD scale heights We obtain accretion rates onlymarginally smaller than those reported by eg DAngelo et al(2003) Bate et al (2003) Bodenheimer et al (2013) who appliedthe same constant kinematic viscosity everywhere including in theCPD As found by several previous studies (eg DrsquoAngelo et al2003 Bate et al 2003 Tanigawa et al 2012 Ayliffe and Bate 2012Gressel et al 2013 Szulaacutegyi et al 2014) the accretion flow does notproceed through the CPD mid-plane but rather at and above theCPD surface hence involving MRI-active regions (Turner et al2014) We conclude that the presence of a dead zone in a CPD doesnot inhibit gas accretion on a giant planet Sustained accretion inthe presence of a CPD is consistent not only with the formation ofJupiter but also with observed extrasolar planets more massivethan Jupiter We place these results in the context of the growthand migration of a pair of giant planets locked in the 21 meanmotion resonance

Author(s) Gennaro DAngelo Francesco MarzariInstitution(s) 1 NASA Ames Research Center 2 University ofPadova

419 ndash Marss Atmosphere41901 ndash Collision-Induced Dissociation CrossSections Relevant to Atmospheric Loss from MarsThe flow onto an atmosphere of the solar wind plasma a plasmatrapped in a planetary magnetic field or a local pick-up ion plasmaproduces chemistry heating and atmospheric loss Theseprocesses which affect its evolution are often lumped together asatmospheric sputtering (Johnson 1994) When the atmospherenear the exobase is atomic then laboratory data calculations orscaled models for the collision cross sections are usually availablefor use in Monte Carlo simulations of atmospheric sputteringHowever atmospheres on a number of planetary bodies havemolecules at the exobase and in the corona for which cross sectiondata is often not available Of particular interest are studies of theatmosphere of Mars in which there can be are significant levels ofCO2 and CO in the exobase region Here we present newcalculations using improved potential energy surfaces of collision-induced dissociation of incident O atoms (~10eV-1keV) formed byneutralization of pick-up O+ incident on CO and CO2 moleculesand compare their importance to our earlier estimates (egJohnson and Liu 1998 Johnson et al 2002) and discuss theirrelevance to simulations of atmospheric loss from Mars

Author(s) Hayley N Williamson Cathy Tully RobertJohnsonInstitution(s) 1 University of Virginia

41902 ndash Modeling Results on the Seasonal Influenceat the Martian ExosphereAnalysis of HST ACSSBC images of Mars in the far-ultraviolettaken in Oct-Nov 2007 and May-November 2014 indicate seasonalinfluence as a driving factor of the hydrogen corona as has beenreported earlier To derive the changes in number density andtemperature the data must be compared to a radiative transfermodel to simulate the resonantly scattered optically thick Lyman αemission from the exosphere of Mars This work presents detailson the modeling process used to analyze the data and thecorresponding uncertainties The escape flux is highly dependenton the characteristics of the martian exosphere like the exobasetemperature and number density of H atoms as well as thepresence or absence of a superthermal population of hydrogenatoms Detailed studies on the workings of the radiative transfermodel indicate degeneracy between temperature and numberdensity values that can fit the data Therefore it is difficult toaccurately determine the characteristics of the martian hydrogenexosphere without independent measurement of at least one of thevariables However HST observations have the advantage ofobserving a large portion of the dayside exosphere with intensityprofiles extending from altitudes of 700 - 30000 km giving a betterestimate of the best-fit temperature and density values whichcharacterize the martian exosphere under different seasonalconditions Comparisons of the latitudinal symmetry from the HSTimages indicate the exosphere to be symmetric beyond 25 martianradii due to the broad trajectories of atoms at high altitudes

Author(s) Dolon Bhattacharyya John Clarke Jean-LoupBertaux Jean-Yves Chaufray Majd MayyasiInstitution(s) 1 Boston University 2 LATMOS

41903 ndash Stationary Planetary Waves in the MarsWinter Atmosphere as seen by the Radio ScienceExperiment MaRS on Mars ExpressStationary (Rossby) Waves are excited by the interaction of thezonally varying topography with the strong eastward winter jetsThey lead to distinctive longitudinal temperature variations whichcontribute significantly to the asymmetry of the seasonal polar CO2ice caps and are also important for the dust redistribution in theplanetary atmosphere

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Radio Science profiles from the Mars Express Radio ScienceExperiment MaRS at northern and southern high latitudes areused to gain insight into winter stationary wave structures on bothhemispheresMars Global Surveyor (MGS) radio occultation measurements fromthe same season and year with their exceptionally goodlongitudinal and temporal coverage can be used to estimate theinfluence of transient eddies Transient waves are especiallyimportant in the northern winter hemisphereWave number 2 stationary waves driven by topography aredominant in the northern winter latitudes while the wave number 1wave is the most significant wave number during southern winterThe wave amplitudes peak around winter solstice on bothhemispheresRadio occultation measurements provide the unique opportunityto determine simultaneous measurements of temperature andgeopotential height structures Assuming geostrophic balancethese measurements can be used to determine meridional windsand eddy heat fluxes which provide further insight into thecontribution of stationary waves to the heat exchange between thepoles and the lower latitudes

Author(s) Silvia Tellmann Martin Paumltzold BerndHaumlusler Leonard G Tyler David P HinsonInstitution(s) 1 Department of Electrical Engineering StanfordUniversity 2 Institut fuumlr Raumfahrttechnik undWeltraumnutzung Universitaumlt der Bundeswehr Muumlnchen 3Rheinisches Institut fuumlr Umweltforschung (RIU) Department ofPlanetary Research

41904 ndash Traveling Waves in the northern hemisphereof Mars - Structure Variability and EnergeticsInvestigations of the variability structure and energetics oftraveling waves in the northern hemisphere of Mars wereconducted with the MarsWRF general circulation model Using asimple annually repeatable dust scenario the model reproducesthe general characteristics of the observed traveling wavesincluding major wave periods and thermal signatures of travelingwaves suppression of transient eddy activity near the surface atnorthern winter solstice and wave mode transitions among zonalwavenumber m = 1 2 and 3 eastward traveling waves near thesurface Simulated wave structures in the temperature field differfrom those in the geopotential field Wave energetics calculationsindicate a mixed baroclinic-barotropic nature for representativewave modes This is consistent with Barnes et al (1993) There is alarge contrast in wave energetics between the near surface andhigher altitudes as well as between the poleward and equatorwardside of the maximum eddy available potential energy at higheraltitudes The modeled transient eddies exhibit strong zonalvariations in kinetic energy and various energy transfer terms Inparticular the eddy kinetic energy for a time period dominated by am = 3 traveling wave shows local maxima in Acidalia Utopia andArcadia which are the origination locations of ldquoflushingrdquo duststorms The eddy kinetic energy for a time period transitioningfrom m = 2 to m = 3 traveling waves shows local maxima in Acidaliaand Utopia There are direct energy exchanges between thermaltides and traveling waves but the exchange rate is much slowerthan other major energetics terms When thermal tides areremoved from the MarsWRF simulation the amplitudes of m = 3traveling waves are greatly reduced In the meantime theisotherms of the northern baroclinic zone slope more towards thepole satisfying an empirical condition for weaker traveling wavesnear the surface However this change cannot fully explain thestrength of the simulated m = 3 traveling waves as both weak andoccasional strong m = 3 waves emerge from very similar zonalmean temperature structures

Author(s) Huiqun Wang Anthony D ToigoInstitution(s) 1 APL 2 SAO

41905 ndash Large-Scale Weather Disturbances in MarsrsquoSouthern ExtratropicsBetween late autumn and early spring Marsrsquo middle and highlatitudes within its atmosphere support strong mean thermal

gradients between the tropics and poles Observations from boththe Mars Global Surveyor (MGS) and Mars Reconnaissance Orbiter(MRO) indicate that this strong baroclinicity supports intenselarge-scale eastward traveling weather systems (ie transientsynoptic-period waves) These extratropical weather disturbancesare key components of the global circulation Such wave-likedisturbances act as agents in the transport of heat and momentumand generalized scalartracer quantities (eg atmospheric dustwater-vapor and ice clouds) The character of large-scale travelingextratropical synoptic-period disturbances in Mars southernhemisphere during late winter through early spring is investigatedusing a moderately high-resolution Mars global climate model(Mars GCM) This Mars GCM imposes interactively lifted andradiatively active dust based on a threshold value of the surfacestress The model exhibits a reasonable dust cycle (ie globallyaveraged a dustier atmosphere during southern spring andsummer occurs) Compared to their northern-hemispherecounterparts southern synoptic-period weather disturbances andaccompanying frontal waves have smaller meridional and zonalscales and are far less intense Influences of the zonallyasymmetric (ie east-west varying) topography on southernlarge-scale weather are examined Simulations that adapt Marsrsquo fulltopography compared to simulations that utilize synthetictopographies emulating key large-scale features of the southernmiddle latitudes indicate that Marsrsquo transient barotropicbarocliniceddies are highly influenced by the great impact basins of thishemisphere (eg Argyre and Hellas) The occurrence of a southernstorm zone in late winter and early spring appears to be anchoredto the western hemisphere via orographic influences from theTharsis highlands and the Argyre and Hellas impact basinsGeographically localized transient-wave activity diagnostics areconstructed that illuminate dynamical differences amongst thesimulations and these are presented

Author(s) Jeffery L Hollingsworth Melinda A KahreInstitution(s) 1 NASA Ames Research Center

41906 ndash The Mars Dust and Water CyclesInvestigating the Influence of Clouds on the VerticalDistribution and Meridional Transport of Dust andWaterThe dust and water cycles are critical to the current Martianclimate and they interact with each other through cloud formationDust modulates the thermal structure of the atmosphere and thusgreatly influences atmospheric circulation Clouds provide radiativeforcing and control the net hemispheric transport of water throughthe alteration of the vertical distributions of water and dust Recentadvancements in the quality and sophistication of both climatemodels and observations enable an increased understanding ofhow the coupling between the dust and water cycles (through cloudformation) impacts the dust and water cycles We focus here on theeffects of clouds on the vertical distributions of dust and water andhow those vertical distributions control the net meridionaltransport of water We utilize observations of temperature dustand water ice from the Mars Climate Sounder (MCS) on the MarsReconnaissance Orbiter (MRO) and the NASA ARC Mars GlobalClimate Model (MGCM) to show that the magnitude and nature ofthe hemispheric exchange of water during NH summer is sensitiveto the vertical structure of the simulated aphelion cloud beltFurther we investigate how clouds influence atmospherictemperatures and thus the vertical structure of the cloud belt Ourgoal is to isolate and understand the importance ofradiativedynamic feedbacks due to the physical processes involvedwith cloud formation and evolution on the current climate of Mars

Author(s) Melinda A Kahre Robert M Haberle Jeffery LHollingsworth Amanda S Brecht Richard A UrataInstitution(s) 1 BAER Institute 2 NASA Ames Research Center

41907 ndash In Situ Observations of Line-of-SightExtinction Reveals the Depth of the PlanetaryBoundary Layer within Gale Crater MarsImagers onboard the Mars Science Laboratory have been used toderive line-of-sight extinction coefficients within Gale Crater Mars

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The images in use have similar pointings and look at roughly thesame section of the north crater rim some 30 km away Theobservations are taken on average once every seven sols and havespanned more than an entire martian year Another longstandingand more frequent observation is one in which the total columnoptical depth above Gale Crater can be derived When comparingthe two datasets one can conclude that the air within the northernpart of the crater supports less dust per volume than the bulkatmosphere above the crater As such little to no mixing has beenobserved between the two air masses More recently line-of-sightextinction variations with height have allowed the depth of theplanetary boundary layer (PBL) to be examined by comparingmorning and noon-time imaging The top of the PBL can be seen asa change in the slope of the extinction Below this change of slopewe observe that the PBL is well mixed with near constantextinction The reduced extinction within the PBL may indicatethat in contrast to other Mars landing sites where mixing isimplicated in dust lifting that the relatively mild dynamics ofmixing at Gale contribute to clearing of the PBL by enhancing thedelivery of dust to the surface Above the PBL extinction increasesrapidly The PBL is typically seen to be shallower than the height ofthe crater rim some 2 km above the crater floor Not only was asuppressed PBL within Gale Crater predicted before landing thefact that extinction is seen to increase above the PBL provides moreevidence that the air mass above the crater initially supports moredust on average than the air lower down in the crater

Author(s) Casey A Moore John E Moores Mark TLemmon Jason Van BeekInstitution(s) 1 Malin Space Science Systems 2 Texas AampMUniversity 3 York University

41908 ndash Ice Cloud Optical Depth Mapping fromMRO-CRISM Multispectral DataThe Mars Reconnaissance Orbiter (MRO) CompactReconnaissance Imaging Spectrometer for Mars (CRISM) multi-spectral mapping data are a reduced spectral sampling mapping setusing only 72 of its 545 channels This reduction allowed forgreater spatial coverage and the creation of nearly complete mapsafter several sols of orbits Using data from late 2006 through early2008 I have created 6 such maps in order to measure ice cloudoptical depth as a function of position for each of them Opticaldepth is retrieved using a DISORT-based radiative transfer code[1]One of the inputs for the code is surface reflectance which is notknown at each point a priori but instead is fit from a linearcombination of surface endmember spectramdashthe endmembercoefficients for each endmember along with dust and ice opticaldepth are adjustable model parameters that are varied until theRMS error between model and data is a minimum Surface spectralendmembers are recovered through a combination of principalcomponent analysis (PCA) and target transformation (TT) whichfirst reduces the dimensionality of the data (from 72 to 4) and thencreates a data cloud in this space of possible potential endmembersderived from best fits of a spectral library [2ndash4] The actualendmembers are chosen from extrema of this candidate cloudI will present six ice cloud optical depth maps made using thistechnique with a 3-endmember surface model[1] Wolff M J personal communication[2] Klassen D R (2013) AASDPS Abstracts 45 31305[3] Klassen D R (2014) LPI Contributions 1791 1384[4] Klassen D R (2014) The Fifth International Workshop on theMars Atmosphere 2303

Author(s) David R KlassenInstitution(s) 1 Rowan Univ

41909 ndash Detections and Sensitive Upper Limits forMethane and Related Trace Gases on Mars during2003-2014 and planned extensions in 2016Five groups report methane detections on Mars all results suggestlocal release and high temporal variability [1-7] Our team searchedfor CH on many dates and seasons and detected it on severaldates [1 9 10] TLS (Curiosity rover) reported methane upperlimits [6] and then detections [7] that were consistent in size with

earlier reports and that also showed rapid modulation of CHabundance[8] argued that absorption features assigned to Mars CH by [1]might instead be weak lines of terrestrial CH If not properlyremoved terrestrial CH signatures would appear on the bluewing of terrestrial CH even when Mars is red-shifted ndash but theydo not (Fig S6 of [1]) demonstrating that terrestrial signatureswere correctly removed [9] demonstrated that including thedependence of δ CH with altitude did not affect the residualfeatures nor did taking δ CH as zero Were δ CH importantits omission would have overemphasized the depth of CHterrestrial absorption introducing emission features in the residualspectra [1] However the residual features are seen in absorptionestablishing their origin as non-terrestrial ndash [8] now agrees withthis viewWe later reported results for multiple organic gases (CH CH OHH CO C H C H C H ) hydroperoxyl (HO ) three nitriles(N O NH HCN) and two chlorinated species (HCl CH Cl) [9]Most of these species cannot be detected with current space assetsowing to instrumental limitations (eg spectral resolving power)However the high resolution infrared spectrometers (NOMADACS) on ExoMars 2016 (Trace Gas Orbiter) will beginmeasurements in late 2016 In solar occultation TGO sensitivitieswill far exceed prior capabilitiesWe published detailed hemispheric maps of H O and HDO onMars inferring the size of a lost early ocean [10] In 2016 we planto acquire 3-D spatial maps of HDO and H O with ALMA andimproved maps of organics with iSHELLNASA-IRTFReferences [1] Mumma et al Sci09 [2] Formisano et al Sci04[3] Krasnopolsky et al Icar04 [4] Fonti and Marzo AampA10 [5]Krasnopolsky Icar12 [6] Webster et al Sci13 [7] Webster et alSci15 [8] Zahnle et al Icar11 [9] Villanueva et al Icar13 [10]Villanueva et al Sci15

Author(s) Michael J Mumma Geronimo L Villanueva Robert E NovakInstitution(s) 1 Iona College 2 NASAs GSFC

41910 ndash Longitudinal Maps of Marsrsquo O (singlet Delta)Emission for L =725deg and L =880degWe report longitudinal maps of the O (singlet Delta) emission rate(a tracer for high-altitude ozone) taken at two seasonal pointsL =725deg (03 April 2010) and L =880deg (10 February 2014) usingCSHELL at NASArsquos IRTF On these dates the entrance slit of thespectrometer was positioned E-W on Mars centered at thesub-Earth point but on 10 Feb 2014 additional spectra were takenwith the slit positioned 3 arc seconds North of the sub-Earth pointOn both dates spectralspatial images (near 127 microns) wererepeatedly taken over a four-hour period Spectral extracts fromthese images were taken at 06 arcsec intervals along the slit Amodel consisting of solar continuum with Fraunhofer linestwo-way transmission through Marsrsquo atmosphere and a one-waytransmission through the Earthrsquos atmosphere was used to isolateand analyze individual spectral lines Boltzmann analysis of theselines yielded the rotational temperature (~175 K) that was used todetermine the total emission rate from the measured linesThe slit on 03 Apr 2010 crossed the morning terminator yieldingmeasurements between 0600-1400 Local Time on 10 Feb 2014the slit went through the evening terminator (1000-1800 LT) Forboth dates data were taken over a four-hour interval in UT Whendisplayed versus local time the extracted emission rates revealsimilar patterns of growth before mid-day and of decline beforesunset regardless of surface topography The measured emissionrates that peak after noon local time depend on the angles to bothSun and Earth The post-noon emission rates (10 Feb 2014) varywith latitude because they depend on the location of thehygropauseThis work was partially funded by grants from NASAs PlanetaryAstronomy Program (344-32-51-96) NASArsquos AstrobiologyProgram (344-53-51) and the NSF-RUI Program (AST-805540)We thank the administration and staff of the NASA-IRTF forawarding observing times and coordinating our observations

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Author(s) Robert E Novak Michael J Mumma GeronimoL VillanuevaInstitution(s) 1 Iona College 2 NASA-GSFC

41911 ndash Diurnal and Interannual Variation inAbsorption Lines of Isotopic Carbon Dioxide in MarsAtmosphereGroundbased observations of Mars in 2003 2007 2012 and 2014have detected transitions of carbon dioxide containing the stableminor isotopes of oxygen and carbon as well as the primaryisotopes using the ultrahigh resolution spectrometer HIPWAC atthe NASA Infrared Telescope Facility The most well characterizedminor isotope is O-18 due to strong lines and observationalopportunities The average estimated O-18O-16 isotope ratio isroughly consistent with other in situ and remote spectroscopicmeasurements but demonstrates an additional feature in that theretrieved ratio appears to increase with greater ground surfacetemperature These conclusions primarily come from analyzing asubset of the 2007 data Additional observations have beenacquired over a broad range of local time and meridional position toevaluate variability with respect to ground surface temperatureThese additional observations include one run of measurementswith C-13 These observations can be compared to local in situmeasurements by the Curiosity rover to narrow the uncertainty inabsolute isotope ratio and extend isotopic measurements to otherregions and seasons on Mars The relative abundance of carbondioxide heavy isotopes on Mars is central to estimating theprimordial atmospheric inventory on Mars Preferential freeze-distillation of heavy isotopes means that any measurement of theisotope ratio can be only a lower limit on heavy isotope enrichmentdue to past and current loss to space

Author(s) Timothy A Livengood Theodor Kostiuk TilakHewagama John R Kolasinski Wade G HenningInstitution(s) 1 CRESSTUMDGSFC 2 NASA GSFC 3University of Maryland

41912 ndash The search for active release of volcanic gaseson MarsThe study of planetary atmospheres by means of spectroscopy isimportant for understanding their origin and evolution Thepresence of short-lived trace gases in the martian atmospherewould imply recent production for example by ongoing geologicactivity On Earth sulfur dioxide (SO ) sulfur monoxide (SO) andhydrogen sulfide (H S) are the main sulfur-bearing gases releasedduring volcanic outgassing Carbonyl sulfide (OCS) also releasedfrom some volcanoes on Earth (eg Erebus and Nyiragongo)could be formed by reactions involving SO or H S inside magmachambers We carried out the first ground-basedsemi-simultaneous multi-band and multi-species search for suchgases above the Tharsis and Syrtis volcanic regions on Mars Thesubmillimeter search extended between 23 November 2011 and 13May 2012 which corresponded to Marsrsquo mid Northern Spring andearly Northern Summer seasons (Ls = 34ndash110deg) The strongsubmillimeter rotational transitions of SO SO and H S weretargeted using the high-resolution heterodyne receiver (akaBarney) on the Caltech Submillimeter Observatory We reachedsensitivities sufficient to detect a volcanic release on Mars that is4 of the SO released continuously from Kilauea volcano inHawaii or 5 that of the Masaya volcano in Nicaragua Theinfrared search covered OCS in its combination band (ν +ν ) at342 μm at two successive Mars years during Marsrsquo late NorthernSpring and mid Northern Summer seasons spanning L = 43 andL = 147 The targeted volcanic districts were observed during thetwo intervals 14 Dec 2011 to 6 Jan 2012 in the first year and 30May 2014 to 16 June 2014 in the second year using the highresolution infrared spectrometer (CSHELL) on NASArsquos InfraredTelescope Facility (NASAIRTF) We will present our results anddiscuss their implications for current volcanic outgassing activityon the red planet We gratefully acknowledge support from theNASA Planetary Astronomy Program under NASA contractNNH14CK55B that supported AK and AT RTOP 344-32-07 andNASArsquos Astrobiology Program (RTOP 344-53-51) that supportedMJM and GLV

Author(s) Alain Khayat Geronimo Villanueva MichaelMumma Alan TokunagaInstitution(s) 1 Catholic University of America 2 Institute forAstronomy 3 NASA Goddard Spaceflight Center

41913 ndash Solar wind Mars interaction during theMAVEN Deep Dip campaigns multi-fluid MHDsimulations based upon the SWIA NGIMS and MAGmeasurementsThe 3-D Mars multi-fluid Block Adaptive Tree Solar-wind RoeUpwind Scheme (BATS-R-US) MHD code is used to study the solarwind interaction with the Martian upper atmosphere during theMAVEN Deep Dip campaigns MAVEN made the firstcomprehensive measurements of Martian thermosphere andionosphere composition structure and variability at altitudesdown to ~130 km in the subsolar region during the second of itsDeep Dip campaigns MAVEN will start its fourth Deep Dipcampaign this September and a large quantity of useful data will bereturned for this study as well In this study we adopt the MAVENmeasurements as the multi-fluid MHD inputs The estimated solarwind density and velocity the estimated interplanetary magneticfield (IMF) and the exactly measured neutral atmosphere profileare taken from the SWIA MAG and NGIMS instrumentsrespectively We will compare the calculated ionosphere ionprofiles with the NGIMS measurements In the meantime we willshow the calculations of the global ion escape rates based uponactual measured neutral atmosphere profiles during the MAVENDeep Dip campaigns

Author(s) Chuanfei Dong Stephen W Bougher YingjuanMa Gabor Toth Shannon M Curry Andrew F Nagy JasperS Halekas Janet G Luhmann Paul Mahaffy Mehdi Benna Jack E P Connerney Jared Espley David L Mitchell David ABrain Bruce M JakoskyInstitution(s) 1 NASA Goddard Space Flight Center 2University of California 3 University of California 4 Universityof Colorado 5 University of Iowa 6 University of Michigan

41914 ndash He Bulge Detection by MAVEN Neutral Gasand Ion Mass Spectrometer (NGIMS) in the UpperAtmosphere of MarsStudies of the Venusian atmospheres have demonstrated enhancedHe densities at high latitudes and on the night-side detections Todetermine if Mars has a similar enhanced He lsquobulgersquo in the sameregion we compared several periapsis passes from night to daysideThe first six weeks of the MAVEN prime mission had periapsis athigh latitudes on the night-side followed by the next three monthsat mid latitudes on the dayside moving to low latitudes on thenight-side In addition to its normal orbit which has a periapsis ofapproximately 150 km MAVEN conducts a few deep dip orbitswhere the spacecraft has a periapsis closer to 125km The first deepdip was at dusk at mid latitudes the second at noon at the equatorwith the third going from dawn to night in the southernhemisphere Initial analysis of the Neutral Gas and Ion MassSpectrometer (NGIMS) closed source data from all orbits with goodpointing revealed an enhanced He density on the night-side orbitsand a decreased He density on the dayside This enhancement ofHe demonstrates a bulge at Mars that will continue to be exploredover the course of the mission

Author(s) Meredith K Elrod Paul R Mahaffy Roger Yelle Shane Stone Mehdi Benna Bruce JakowskiInstitution(s) 1 NASA Goddard SFC 2 University of Arizona3 University of Colorado Boulder

41915 ndash New Observations of Molecular Nitrogen bythe Imaging Ultraviolet Spectrograph on MAVENThe Martian ultraviolet dayglow provides information on the basicstate of the Martian upper atmosphere The Imaging UltravioletSpectrograph (IUVS) on NASArsquos Mars Atmosphere and VolatileEvolution (MAVEN) mission has observed Mars at mid and far-UVwavelengths since its arrival in September 2014 In this work wedescribe a linear regression method used to extract components ofUV spectra from IUVS limb observations and focus in particular on

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molecular nitrogen (N ) photoelectron excited emissions Weidentify N Lyman-Birge-Hopfield (LBH) emissions for the firsttime at Mars and we also confirm the tentative identification of NVegard-Kaplan (VK) emissions We compare observed VK andLBH limb radiance profiles to model results between 90 and 210km Finally we compare retrieved N density profiles to generalcirculation (GCM) model results Contrary to earlier analyses usingother satellite data that indicated N densities were a factor of threeless than predictions we find that N abundances exceed GCMresults by about a factor of two at 130 km but are in agreement at150 km

Author(s) Michael H Stevens J S Evans Nicholas MSchneider AIF Stewart Justin Deighan Sonal K Jain Matteo MJ Crismani Arnaud Stiepen Michael S Chaffin William E McClintock Greg M Holsclaw Franck Lefevre Franck Montmessin Daniel Y Lo John T Clarke Stephen WBougher Bruce M JakoskyInstitution(s) 1 Center for Space Physics Boston University 2Computational Physics Inc 3 Department of Climate and SpaceSciences and Engineering University of Michigan 4 Laboratoryfor Atmospheric and Space Physics 5 LATMOSCNRS 6 Lunarand Planetary Laboratory University of Arizona 7 Space ScienceDivision Naval Research Laboratory

41916 ndash Two Types of Aurora on Mars as Observed byMAVENs Imaging UltraViolet SpectrographThe Imaging UltraViolet Spectrograph (IUVS) on the MAVENspacecraft has detected two distinct types of auroral emission onMars First we report the discovery of a low altitude diffuse auroraspanning much of Marsrsquo northern hemisphere coincident with asolar energetic particle outburst IUVS observed northerly latitudesduring late December 2014 detecting auroral emission in virtuallyall nightside observations for ~5 days spanning virtually allgeographic longitudes The vertical profile showed emission downto ~70 km altitude (1 microbar) deeper than confirmed at anyother planet The onset and duration of emission coincide with theobserved arrival of solar energetic particles up to 200 keVprecipitating directly and deeply into the atmosphere Preliminarymodeling of the precipitation energy deposition and spectral lineemission yields good matches to the observations Theseobservations represent a new class of planetary auroras producedin the Martian middle atmosphere Given minimal magnetic fieldsover most of the planet Mars is likely to exhibit aurora moreglobally than EarthSecond we confirm the existence of small patches of discreteaurora near crustal magnetic fields in Mars southern hemisphereas observed previously by SPICAM on Mars Express (Bertaux et alNature 435 790-794 (2005)) IUVS observed southern latitudes inJuly and August 2015 detecting discrete auroral emission in ~1of suitable observations Limb scans resolved both vertically andalong-slit indicate this type of auroral emission was patchy on thescale of ~40 km and located at higher altitudes ~140 km Thehigher altitudes imply a lower energy of precipitating particles Themix of spectral emissions also differed signficiantly from the diffuseaurora indicating different excitation and quenching processesWe will discuss the observed properties of the aurora andassociated charged particle precipitation as well as the broaderimplications of this high-energy deposition into Mars atmopshere

Author(s) Nicholas M Schneider J Deighan SK Jain A Stiepen D Larson DL Mitchell CO Lee R Lillis DBrain WE McClintock MS Chaffin M Crismani GMHolsclaw BM Jakosky C Mazelle JS Evans AIFStewart MH Stevens JT Clarke F Montmessin FLefevre D LoInstitution(s) 1 Center for Space Physics Boston University 2CNRS Institut de Recherche en Astrophysique et PlaneacutetologieFrance 3 Computational Physics Inc 4 LASP Univ ofColorado 5 LATMOSIPSL 6 Space Science Division NavalResearch Laboratory 7 Space Sciences Lab University ofCalifornia at Berkeley

41917 ndash Combined analysis of Far UV and Mid UV

spectra obtained by the MAVEN IUVS instrument in aStellar Occultation ModeIn this presentation we will focus on the results obtained by theImaging Ultraviolet Spectrograph (IUVS) onboard the MarsAtmosphere and Volatile and Evolution (MAVEN) mission whileperforming stellar occultations observations In the IUVSwavelength range CO possesses a distinct and broad signatureshortward of 200 nanometers which allows one to retrieve COconcentration and subsequently to deduce atmospheric pressureand temperature profiles from 30 to 150 km of altitude (uppertroposphere up to the thermosphere) as well as the concentrationof other atmospheric consitituents (cloudsaerosols ozone andmolecular oxygen) The occultation technique relies on thedetermination of atmospheric transmission at various altitudesabove the surface Only relative measurements are needed to inferspecies abundances and thus the method is self-calibratedThe ratio of spectra taken through (close to Mars) and outside (farfrom Mars) the atmosphere gives an atmospheric transmission ateach altitude If any absorbing orand scattering species is presentalong the optical path photons are lost and resulting transmissionsare lower than 1 The sampling rate yields a vertical resolutiontypically greater than 3 km on the vertical For Mars the soundedregion inside which a quantity of atmospheric constituents can bederived lies generally between 20 and 150 km depending on theatmospheric state (dust loading) The compiled dataset has alreadyyielded a variety of results showing high concentrations of ozonein the deep polar night as well as the detection of a highly elevatedaerosol layer potentially made of CO ice

Author(s) Franck Montmessin Hannes Groeller GaeacutetanLacombe Nicholas M Schneider Roger Yelle Ian Stewart Justin Deighan John Clarke Franck Lefevre Lucio Baggio William E McClintock Gregory M Holsclaw Bruce MJakoskyInstitution(s) 1 Boston University 2 CNRS LATMOS 3 LASP4 LPL

41918 ndash MAVENIUVS Observations of the GaseousPerturbation from Comet C2013 A1 (Siding Spring)on Mars and its Constant Metallic Ion LayerThe close passage of comet C2013 A1 (Siding Spring) by Marsafforded the newly arrived Mars Atmosphere and VolatileEvolutioN (MAVEN) mission the opportunity to observe acometary perturbation to the upper atmosphere The mostdramatic atmospheric effect was the ablation of cometary dust thatproduced a transient metallic ion layer near 120 km higher thanthe predicted (90 km) constant metallic ion layer from sporadicdust ablation due to the extreme relative velocity of the comet (56kms) Additionally cometary gases such as H O CO and theirdaughter species delivered mass and energy to the upperatmosphere where the temperature at 150 km was predicted toincrease by 30 KThe Imaging Ultraviolet Spectrograph (IUVS) on MAVEN takeslimb scans at periapse to construct altitude profiles of variousultraviolet species Using a Multiple Linear Regression (MLR)technique to extract spectral features we analyze the observationsof the perturbed atmosphere to determine whether the gaseousmass and energy deposition is distinguishable within typicalatmospheric variation Furthermore we use all subsequent daysideobservations to identify the metallic ion layer represented by thepresence of Mg and compare these observations with a robustnumerical model of ablation CAMBOD (Chemical AblationModel)

Author(s) Matteo Michael James Crismani NicholasSchneider Sonal Jain John Plane Justin DeighanInstitution(s) 1 CU Boulder 2 Laboratory for Atmospheric andSpace Physics 3 University of Leeds

41919 ndash The ExoMars 2016 missionThe ExoMars programme is a joint activity by the European SpaceAgency (ESA) and ROSCOSMOS Russia It consists of theExoMars 2016 mission with the Trace Gas Orbiter TGO and theEntry Descent and Landing Demonstrator Schiaparelli and the

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Exomars 2018 mission which carries a lander and a roverThe TGO scientific payload consists of four instruments These areACS and NOMAD both infrared spectrometers for atmosphericmeasurements in solar occultation mode and in nadir modeCASSIS a multichannel camera with stereo imaging capability andFREND an epithermal neutron detector for search of subsurfacehydrogen ESA is providing the TGO spacecraft and the SchiaparelliLander demonstrator and two of the TGO instruments andROSCOSMOS is providing the launcher and the other two TGOinstrumentsAfter the arrival of the ExoMars 2018 mission at the surface ofMars the TGO will handle the communication between the Earthand the Rover and lander through its UHF communication systemThe 2016 mission will be launched by a Russian Proton rocket fromBaikonur in January 2016 and will arrive at Mars in October thesame year This presentation will cover a description of the 2016mission including the spacecraft its payload and science and therelated plans for scientific operations and measurements

Author(s) Haringkan Svedhem Jorge Vago Rolf de GrootInstitution(s) 1 ESAESTEC

41920 ndash Self- and CO -broadened line shapeparameters for infrared bands of HDOKnowledge of CO -broadened HDO line widths and theirtemperature dependence is required to interpret infrared spectra ofthe atmospheres of Mars and Venus However this information iscurrently absent in most spectroscopic databases We haveanalyzed nine high-resolution high signal-to-noise spectra of HDOand HDO+CO mixtures to obtain broadening coefficients andother line shape parameters for transitions of the ν and νvibrational bands located at 713 and 270 μm respectively The gassamples were prepared by mixing equal amounts of high-puritydistilled H O and 99 enriched D O The spectra were recorded atdifferent temperatures (255-296 K) using a 2038 cm long coolablecell [1] installed in the sample compartment of the BrukerIFS125HR Fourier transform spectrometer at the Jet PropulsionLaboratory in Pasadena CA The retrieved HDO spectroscopicparameters include line positions intensities self- andCO -broadened half-width and pressure-induced shift coefficientsand the temperature dependences for CO broadening Thesespectroscopic parameters were obtained by simultaneousmultispectrum fitting [2] of the same interval in all nine spectra Anon-Voigt line shape with speed dependence was applied Linemixing was also observed for several transition pairs Preliminaryresults compare well with the few other measurements reported inthe literature[1] K Sung et al J Mol Spectrosc 162 124-134 (2010)[2] D C Benner et al J Quant Spectrosc Radiat Transfer 53705-721 (1995)The research performed at the College of William and Mary wassupported by NASArsquos Mars Fundamental Research Program(Grant NNX13AG66G) The research at Jet Propulsion LaboratoryCalifornia Institute of Technology Connecticut College LangleyResearch Center and Goddard Space Flight Center was conductedunder contracts and cooperative agreements with the NationalAeronautics and Space Administration RRG is pleased toacknowledge support of this study by the National ScienceFoundation through Grant No AGS-1156862

Author(s) Mary-Ann H Smith V Malathy Devi D ChrisBenner Keeyoon Sung Arlan W Mantz Robert R Gamache Geronimo L VillanuevaInstitution(s) 1 Connecticut College 2 Jet PropulsionLaboratory California Institute of Technology 3 NASA GoddardSpace Flight Center 4 NASA Langley Research Center 5 TheCollege of William and Mary 6 University of Massachusetts

41921 ndash Simulating Helium abundances in theMartian upper atmosphere using 1-D and 3-D modelsChemically inert species such as Helium serve as an excellenttracer for the interplay between turbulent eddy diffusive processesand molecular diffusive processes Using species such as Heliumwe can effectively constrain the altitude of the homopausemdashor the

transition from the well-mixed lower atmosphere to themass-separation characteristic of the upper atmosphere In thisstudy we will use the Mars Global Ionosphere-ThermosphereModel (M-GITM) to examine the impacts of altering the turbulentdiffusion coefficient (eddy diffusion coefficient) on the simulatedabundances of Helium Using data obtained by the Neutral Gas andIon Mass Spectrometer (NGIMS) onboard the Mars Atmosphereand Volatile Evolution (MAVEN) mission as a benchmark we canexamine what possible values for eddy diffusion in thethermosphere are most likely present in Marsrsquos upperatmospheremdashin other words we can assess where the meanhomopause altitude is most likely located during the MAVENmission Furthermore we will compare and contrast the resultsobtained when using a strictly classical 1-D treatment of theproblem with a more complete coupled global 3-D treatment of theMartian atmosphere

Author(s) Jared M Bell S W Bougher Paul Mahaffy Meredith ElrodInstitution(s) 1 Goddard Space Flight Center 2 NationalInstitute of Aerospace 3 University of Michigan

41922 ndash Boundary location of Mars nightsideionospheric plasma in term of the electron densityPhoto-ionized Mars atmosphere is forming an ionosphere andshielding the solar wind with creating barriers of bow shock Insidethe bow shock ionospheric plasma interact with solar wind plasmaand result different boundaries A question is how far theionospheric plasma can stand off the solar windOn the dayside in-situ data set from Mars magnetosphere missionsoften observed the sharp gradient of the thermal plasma flux andion composition change as well as the drop off of the magneticfluctuation simultaneously as a outer boundary of the ionosphericplasma and an obstacle to the solar wind Several models haveconstructed the shape of the boundary based on the statisticalobservations [eg Trotignon et al 2006 Edberg et al 2008]On the nightside plasma instrument onboard Phobos 2 observedthe particles and magnetic field characteristics similar to thedayside However the number of data is still too few to understandthe general location of boundaries We will present thecharacteristics of the nightside magnetospheric boundary region interm of the electron density MAVEN Langmuir probemeasurement (LPW) can estimate the electron density using thespacecraft environment As MAVEN pass from the bow shock andsheath region into the magnetosphere the electron density oftenshow a sharp gradient (the density jumps two orders of magnitudesin a few seconds) Comparing this to the data from particleinstrument the sharp electron density gradient was oftenassociated with the transition of the characteristic energy of ionsSeveral hundreds of boundaries crossing by MAVEN allow us toinvestigate the statistical view of the boundary We searched for alarge electron density gradient as an indicator of the plasmaboundary to identify the location of the ionosphericsolar windplasma boundary The results show that the many of the nightsideboundaries locates close to the tail region of Mars forming ellipticalshape of boundary We will provide the empirical model of thisboundary location and discuss the influence of solar wind

Author(s) Michiko W Morooka Laila Andersson BobErgun Christopher Fowler Adam Woodson Tristan Weber Greg Delory David Andrews Niklas Edberg Anders Eriksson David Michell Jack Connerney Jacob Gruesbeck JasperHalekasInstitution(s) 1 Department of Physics and AstronomyUniversity of Iowa 2 Laboratory for Atmospheric and SpacePhysics University of Colorado at Boulder 3 NASAGSFC 4Space Sciences Laboratory amp Center for Integrative PlanetarySciences University of California Berkeley 5 Space SciencesLaboratory University of Calfolnia Berkeley 6 Swedish Instituteof Space Physics

41923 ndash Examining Traveling Waves in MarsAtmosphere ReanalysesSynoptic-scale eddies (traveling waves) are a key feature of the

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variability of Mars atmosphere weather in the extratropics and arelinked to the initiation of dust storms Mars reanalyses whichcombine satellite observations with simulations from a Mars GlobalClimate Model (MGCM) provide a four-dimensional picture of theevolution of these waves in terms of temperature winds pressureand aerosol fields The Ensemble Mars Atmosphere ReanalysisSystem (EMARS) has created multiple years of Mars weather mapsthrough the assimilation of Thermal Emission Spectrometer (TES)and Mars Climate Sounder (MCS) temperature profiles using theensemble Kalman filter and the GFDL MGCM We investigate therobustness of the synoptic eddies to changes in the aerosol fieldsmodel parameters data assimilation system design andobservation dataset (TES vs MCS) We examine the evolution ofwavenumber regimes their seasonal evolution and interannualvariability Finally reanalysis fields are combined with spacecraftvisible imagery (eg MGS Mars Orbital Camera) demonstrating thelink between meteorological fields (temperature pressure andwind) and dust fronts

Author(s) Steven J Greybush R John WilsonInstitution(s) 1 GFDL 2 The Pennsylvania State University

41924 ndash Abiotic production of NO3 in the atmosphereof Early MarsRecent CuriositySAM measurements of Martian sediments haveshown the presence of NO3 trapped in the samples The ratio ofnitrate to perchlorate has been suggested to be an indicator forhabitability (Stern et al 2015) However the efficiency of theproduction of nitrate in the atmosphere has never been studied forthe case of the active young Sun To evaluate the effect of theabiotic production of nitrates we apply our 1D atmosphericphotochemical collisional model for the nitrogen-rich and CO2atmosphere of early Mars and calculate the production rate of NO3mediated by the precipitation of energetic particles associated withthe coronal mass ejections from the young SunWe propose a method to check the hypothesis of the abioticproduction if the production is driven by the precipitatingparticles then the magnetic shielding would reduce the NO3production at the equator Thus samples collected at high latitudesshould contain greater concentration of nitrates if the weatheringdid not homogenize it

Author(s) Guillaume Gronoff vladimir airapetian EricHebrardInstitution(s) 1 NASA GSFC 2 SSAI Nasa LaRC

41925 ndash New Approaches in estimating Dust DevilParameters Trajectories and Populations fromSingle-Station Measurements on Mars and EarthA Monte-Carlo modeling approach (Lorenz J Atm Sci 2014)using a power law population function and empirical correlationsbetween diameter and longevity can be used to reconcile single-station pressure records of vortex close-approaches with visualcounts of dust devils and Large Eddy Simulations (LES) That worksuggests that on Earth the populations can be reconciled ifdust-lifting occurs with a typical threshold corresponding to corepressure drop of 08 mb a little higher than the ~03 mb estimatedin laboratory experiments A similar analysis can be conducted atMars The highest vortex production rates in LES indicated fromfield encounters and extrapolated from visual counts appear to beof the order of 1000 per km2 per dayRecent field experiments at a playa near Goldstone CA (Lorenz etal Bulletin of the Seismological Society of America in press) showthat dust devils cause a ground tilt due to the negative pressureload of the vortex on the elastic ground that can be detected with abroadband seismometer like that on InSight Dust devils thereforecan serve as a lsquoseismic sourcersquo to characterize the shallowsubsurfaceObservations of the InSight landing area in Elysium by Reiss andLorenz (Icarus submitted) show that dust devil trails areabundant but smaller in diameter than those at Gusev This mayindicate a shallower Planetary Boundary Layer (PBL) at this siteand season Fenton and Lorenz (Icarus 2015) found that observeddust devil height and spacing in Amazonis relates to the PBL

thicknessQuantitative assessment of dust devil effects (eg electrical andmagnetic signatures) requires knowledge of encounter geometrynotably miss distance A recent heuristic approach has beendeveloped (Lorenz Icarus submitted) to fit an analytic vortexmodel to pressure windspeed and direction histories to recoverthis geometry Some ambiguities exist but can be constrained withcamera images andor the azimuth history estimated from seismicdata

Author(s) Ralph LorenzInstitution(s) 1 JHUAPL

41926 ndash Response of the Martian inducedmagnetosphere to variations in solar forcingSolar forcing and compression of Mars induced magnetospheremay play an important role in oxygen loss at Mars via enhancedionization and heating of the lower atmosphere and in theformation of ambipolar electric fields in the upper atmosphereSteep electron temperature gradients in the upper atmosphere canproduce strong ambipolar fields at altitudes where collisions areinfrequent leading to increased outflow of O and O Suchenhanced escape has been observed in simulations of Marsrsquoionosphere where the ambipolar field was artificially varied to studyits influence on escape It is important therefore to understandhow solar wind forcing modulates electron density- andtemperature-versus-altitude profiles in Mars ionosphereDuring the first five days of May 2015 MAVENrsquos Langmuir Probeand Waves Instrument (LPW) observed variations in the locationand extent of the transition region between the shocked solar windand the Martian ionosphere in the dayside hemisphere Solar winddensities and velocities derived from MAVENrsquos Solar Wind IonAnalyzer (SWIA) indicate that the solar wind dynamic pressure wasalso highly variable during this period In this work we investigatehow the shapes of the electron density- and temperature-versus-altitude profiles measured by LPW depend on the location andextent of the transition region as determined from Solar WindElectron Analyzer (SWEA) spectra and on solar wind forcing asdetermined from SWIA and MAVEN Magnetometer (MAG)measurements over this five-day period

Author(s) Adam Woodson Tristan Weber LailaAndersson Robert Ergun David Andrews Tiffany Chamandy John Connerny Greg Delory Anders Eriksson ChristopherFowler Jasper Halekas Paul Mahaffy David Mitchell Michiko MorookaInstitution(s) 1 CU Boulder Laboratory for Atmospheric andSpace Physics 2 NASA Goddard Space Flight Center 3 SwedishInstitute of Space Physics 4 U Iowa Department of Physics andAstronomy 5 UC Berkely Space Sciences Laboratory

420 ndash Mars Surface and Interior42001 ndash First results of the PlanetFour CitizenScience projectPlanetFour (httpwwwplanetfourorg) is a Citizen Science projectabout analyzing surface images from the south pole of Mars Mainobjectives are studying the surface atmosphere interactions at thepole especially during the local spring CO2 gas jets that are createdby basal sublimation of the seasonal CO2 ice layer deposit fine dustinto the atmosphere and coarser regolith on top of the ice sheet inform of fan-shaped albedo features The fine dust that entered theatmosphere is believed to have an important effect on theatmospheric temperature profile The seasonal removal of regolithover many years results in topographical features calledaraneiform These are dendritic troughs that connect to a commoncenter Their constant modification represents ongoing change inthe surface topography of Mars todayA further objective is to map the orientations of the regolithdeposits These orientations are controlled by the local winds thatexisted at the time of jet eruption Repeated surface observationsconstrain the time of eruption and are therefore able to providewind data points for atmospheric meso-scale simulations

2 1

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2 5 31 4 2 5

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The image data used in the PlanetFour project comes from theHiRISE camera of the Mars Reconnaissance Orbiter Planet Fourcitizens are asked to identify and outline fans in the presented tilesWe cluster the resulting markings into final locations using theDBScan clustering algorithm after which the object coordinates areback-projected into latitude and longitude coordinates with astandard ISIS image calibration pipelineOutcomes are catalogs of object locations estimated sizes and winddirections With these catalogs we study the activity over time perregion compare these activity time-series between seasons andcompare the strength of observed activity between different regionsaround the pole The derived wind directions are used to improveatmospheric meso-scale simulations at Marsrsquo south pole which ispart of an ongoing NASA SSW project We will present results fromthe first publication of the PlanetFour project

Author(s) Klaus-Michael Aye Meg Schwamb GannaPortyankina Candice J HansenInstitution(s) 1 Institute of Astronomy amp AstrophysicsAcademia Sinica 2 Planetary Science Institute 3 University ofColorado Boulder

42002 ndash Mineralogical Stratigraphy of GangesChasma MarsMarsrsquo Valles Marineris canyon system reveals a several-kilometerdeep stratigraphies sequence that extends thousands of kilometersthis sequence thus represents a unique opportunity to exploremillions of years of volcanic and aqueous activity in this region ofMars Of particular interest to the study of both volcanic andaqueous processes is Ganges Chasma which lies on thenortheastern boundary of the Valles Marineris canyon system onMars The canyon likely opened during the Late Noachian to EarlyHesperian modifying previously emplaced Noachian-aged volcanicplains During formation volcanic activity from the nearby Tharsisshield complex emplaced olivine-rich dikes throughout the regionAfter formation sulfate-bearing Interior Layered Deposits (ILDs)were emplaced in Ganges and many other chasmata throughoutthe Valles Marineris system Today Ganges reveals a complexstratigraphy including wide-spread olivine-rich sands hydratedminerals on the plateaus surrounding the canyon and a centralsulfate-rich ILD Here we present updated stratigraphies ofGanges Chasma using new data from the CompactReconnaissance Imaging Spectrometer for Mars (CRISM) andsynthesizing it with previous data sets Olivine sands are tracedback to source outcrops on the canyon floor and new outcrops ofhydrated minerals on the surrounding plateau are identified andmapped Recently reported spectroscopic signatures of ankeriteand smectite in the chasm are assessed and new olivine-richoutcrops identified and mapped Understanding the stratigraphy ofGanges Chasma will help us compare stratigraphies among thechasmata of the Valles Marineris further building ourunderstanding of the geologic history of this large region of Mars

Author(s) Selby Cull-Hearth M Caroline ClarkInstitution(s) 1 Bryn Mawr College

42003 ndash ChemCam at Gale Crater Highlights andDiscoveries from Three Years of ChemicalMeasurements on MarsChemCam has undertaken a detailed chemical investigation of therocks and soils at Gale crater over the last three years with over sixthousand separate geochemical measurements Recentrecalibration of the ChemCam data using a new library of gt350geochemical standards has enabled increased elemental accuraciesover a wider compositional range The increased accuracycombined with ChemCamrsquos small spot size allows for the chemistryof mineral end members including feldspars high silica oxide richgrains to be identified ChemCam has observed both sedimentaryand igneous compositions Igneous compositions are generallypresent in conglomerates and in float rocks Compositions show awide range of igneous chemistry ranging from basaltic to feldsparrich assemblagesSedimentary rocks have a wide range of compositions reflectingboth differences in chemical source regions and in depositional and

diagenetic histories The ldquoSheepbedrdquo mudstones cluster aroundMartian average crustal compositions The ldquoKimberleyrdquo outcropshowed enhanced potassium reaching concentrations up to ~6 wtK O More recent observations in the Murray Formation at thebase of Mt Sharp reveal mudstones that are lower in magnesiumand higher in silica and aluminum than the more basalticmudstones previously investigated Extremely high silica (75-85wt) deposits have also been identified The high silicaobservations were associated with increased TiO While theMurray mudstones are generally low in magnesium localenhancements in magnesium have also been noted associated withresistant facies in the outcrop Chemical trends also indicate thatiron oxide phases may also be present as cements Sandstone facieswith a mafic composition are also present Veins in the unit alsoshow a wide range of compositions indicating fluid chemistries richin calcium sulfate fluorine magnesium and iron were presentVein chemistry could be the result of distinct fluids migratingthrough from a distance with a pre-established chemical signaturefluids locally evolved from water rock interactions or both Thusthe chemical relationships between the Pahrump bedrock and theveinsrsquo chemistry can be used to constrain the origin of the fluids

Author(s) Diana L Blaney Roger Wiens SylvestreMaurice Olivier Gasnault Ryan Anderson John Bridges Nathan Bridges Samuel Clegg Benton Clark BethanyEhlmann Melinda D Dyar Martin Fisk Raymond Francis Cecile Fabre Olivier Forni Jens Frydenvang JefferyJohnson Nina Lanza Richard Leveille Jeremie Lasue Laetitia Le Deit Nicholas Mangold Noureddine Melikechi Marion Nachon Horton Newsom Valerie Payre WilliamRapin Violane Sautter David Vaniman John Grotzinger Ashwin Vasavad Joy CrispInstitution(s) 1 Aplied Physics Laboratory 2 CaliforniaInstitute of Technology 3 Deleware State University 4 John HChapman Space Centre 5 Los Alamos National Laboratory 6Mount Holyoke College 7 Museum National dHistorie Naturelle8 NASA Jet Propulsion Laboratory California Institute ofTechnology 9 Oregon State University 10 Planetary ScienceInstitute 11 Space Science Institute 12 Universiteacute Paul SabatierUPS-OMP Institute de Recherche en Astrophysique et Planetologie(IRAP) 13 University Lorraine 14 University of Copenhagen 15University of Leicester 16 University of New Mexico 17Univertisty of Nantes 18 US Geologic Survey

42004 ndash Sub-surface gas flow in porous bodiesGas flow within porous media is of importance for various bodies inthe Solar System It occurs within the Martian soil might besignificant in the porous interiors of comets and also within dustyplanetesimals in the Solar Nebula In regimes of low atmosphericpressure thermal creep leads to an efficient gas flux if temperaturegradients are present eg by solar insolation This flow can lead toerosion or supports the exchange of volatiles within a porous bodyExperiments showed that this gas flux dominates over diffusive gastransport under Martian conditions with gas velocities on the orderof cms Results from the Rosetta spacecraft suggest that eolianprocesses occur on comets which might be related to thermal creepgas flow Here we present new results of microgravity experimentson a thermally induced gas flow Gas velocities and theirdependence on the atmospheric pressure for different gases(Helium and air) are studied as well as the influence of thegeometry of the pores

Author(s) Jens Teiser Mathias Schywek Caroline de Beule Gerhard WurmInstitution(s) 1 University Duisburg-Essen

42005 ndash Permeability Barrier Generation in theMartian LithospherePermeability barriers develop when a magma produced in theinterior of a planet rises into the cooler lithosphere and crystallizesmore rapidly than the lithosphere can deform (Sparks andParmentier 1991) Crystallization products may then clog theporous network in which melt is propagating reducing thepermeability to almost zero ie forming a permeability barrier

3 13 2

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Subsequent melts cannot cross the barrier Permeability barriershave been useful to explain variations in crustal thickness atmid-ocean ridges on Earth (Magde et al 1997 Hebert andMonteacutesi 2011 Monteacutesi et al 2011) We explore here under whatconditions permeability barriers may form on MarsWe use the MELTS thermodynamic calculator (Ghiorso and Sack1995 Ghiorso et al 2002 Asimow et al 2004) in conjunctionwith estimated Martian mantle compositions (Morgan and Anders1979 Waumlnke and Dreibus 1994 Lodders and Fegley 1997Sanloup et al 1999 Taylor 2013) to model the formation ofpermeability barriers in the lithosphere of Mars In order torepresent potential past and present conditions of Mars we varythe lithospheric thickness mantle potential temperature (heatflux) oxygen fugacity and water contentOur results show that permeability layers can develop in thethermal boundary layer of the simulated Martian lithosphere if themantle potential temperature is higher than ~1500degC The variousMartian mantle compositions yield barriers in the same locationsunder matching variable conditions There is no significantdifference in barrier location over the range of accepted Martianoxygen fugacity values Water content is the most significantinfluence on barrier development as it reduces the temperature ofcrystallization allowing melt to rise further into the lithosphereOur lower temperature and thicker lithosphere model runs whichare likely the most similar to modern Mars show no permeabilitybarrier generation Losing the possibility of having a permeabilitybarrier likely changed the character of volcanism on Mars maybepreventing the formation of new localized volcanic edifices in theAmazonian

Author(s) Joe Schools Laurent MonteacutesiInstitution(s) 1 University of Maryland

42006 ndash New estimates of the Martian landers androvers coordinates by combining Doppler data andtopography modelWe propose here a new method to determine the three coordinatesof a spacecraft landed on Mars with a high accuracy as early as thevery beginning of the mission The method consists of determiningfirst the in-equatorial plane coordinates with Doppler data only andthen inferring the Z-coordinate (along the polar axis) using theMOLA topography model The method is applied to several landedmissions providing good estimate of the Z-coordinate of Vikinglander 1 Pathfinder and Spirit but failing to improve the Z ofOpportunity and Viking lander 2 Finally the method is applied inthe InSight landing ellipse showing the high probability to getInSightrsquos Z coordinate with a precision better than 10m after only acouple of days of observations

Author(s) Sebastien Le MaistreInstitution(s) 1 Jet Propulsion Laboratory

500 ndash Comet 67PC-G -- Nucleus50001 ndash Mass Density and Composition of theNucleus 67PChuryumov-GerasimenkoCometary nuclei consist mostly of dust and water ice but theinternal structure of a comet nucleus is essentially unknown Bulkproperties such as mass volume (size and shape) and particularlythe density must be known for constraining its internal structureThe radio science experiment RSI on the Rosetta spacecraft derivedthe mass and the gravity field of comet 67PChuryumov-Gerasimenko at distances varying between 100 km and 10 km andtogether with the current best estimates of the volume by theOSIRIS camera the bulk density of the nucleus A model of theinternal structure is derived from the information of two shapemodels by comparing observed and theoretical gravity coefficientsThe comet nucleus appears to be a body of low mass low densityand high porosity with approximately four times more dust than iceby mass and 15 times more dust than ice by volume

Author(s) Martin Paetzold Tom Andert Matthias Hahn Sami W Asmar Jean-Pierre Barriot Michael K Bird BerndHaumlusler Kerstin Peter Silvia A Tellmann Eberhard Gruumln Paul Weissman Holger Sierks Laurent Jorda FrankPreusker Frank ScholtenInstitution(s) 1 Max-Planck-Institute for Nuclear Physics 2Institut fuumlr Planetenforschung DLR-Berlin-Adlershof 3 JetPropulsion Laboratory Caltech 4 Laboratoire dAstrophysique deMarseille 5 Max-Planck-Institut fuumlr Sonnensystemforschung 6Rheinisches Institut fuumlr Umweltforschung an der Universitaumlt zuKoumlln 7 Universitaumlt der Bundeswehr Muumlnchen 8 Universite de laPolynesie Francaise

50002 ndash MIRO Observations of subsurfacetemperatures of the nucleus of 67PChuryumov-GerasimenkoObservations of the nucleus of 67PChuryumov-Gerasimenko inthe millimeter-wave continuum have been obtained by theMicrowave Instrument for the Rosetta Orbiter (MIRO) We presentpre-perihelion data obtained at wavelengths of 05 mm and 16 mmduring August 2014-July 2015 over a range of heliocentric distancebetween 362 and 125 AU The data are fit to simple models of thenucleus thermal emission in order to characterize the observedbehavior and make quantitative estimates of important physicalparameters including thermal inertia and absorption properties atthe MIRO wavelengths MIRO brightness temperatures on theirregular surface of 67PC-G are strongly affected by the local solarillumination conditions and there is a strong latitudinaldependence of the mean brightness temperature as a result of theseasonal orientation of the comets rotation axis with respect to theSun The MIRO emission exhibits strong diurnal variations whichindicate that it arises from within the thermally varying layer in theupper centimeters of the surface The data are quantitativelyconsistent with very low thermal inertia values between 10-30 JK m s with the 05 mm emission arising from 1 cm beneaththe surface and the 16 mm emission from a depth of 4 cm TheMIRO brightness temperatures are also affected by the sublimationof ice at or beneath the surface and provide a valuable constraint ondistribution of the water production from the nucleus

Author(s) F Peter Schloerb Stephen Keihm Paul vonAllmen Mathieu Choukroun Emmanuel Lellouch CedricLeyrat Samuel Gulkis Mark HofstadterInstitution(s) 1 JPL 2 LESIA-Observatoire de Paris 3 Univof Massachusetts

50003 ndash Meter-scale thermal contraction crackpolygons on comet 67PChuryumov-GerasimenkoSince August 2014 high spatial resolution images of the nucleus ofcomet 67PChuryumov-Gerasimenko have been acquired by theOSIRIS camera onboard Rosetta enabling to identify meter-scalefeatures on the surface (Thomas et al 2015 El-Maary et al 2015)Here we report on the detection and characterization of thermalcontraction polygons We have identified more than 6000 polygonson 67P using OSIRIS images with a spatial resolution down to 16mpixel They are observed in consolidated terrains from flatterrains to steep terrains such as cliffs and pit walls The size ofpolygons is in the range 1 ndash 10 m with a mean value of 3 mPolygons detected on 67P show morphologies with an elevatedcenter Polygons are known to form on Mars and Earth when thethermal stress of the surface icy materials exceeds their tensilestrength therefore forming fractures (Lachenbruch 1962Mangold 2005 Marchant amp Head 2007) The size shape andspatial distribution of polygons across the surface provideconstraints on their formation and evolution processes thesub-surface water ice content the thermal history of the surfaceand the mechanical properties of the surface material (eg Mellonet al 2008 Levy et al 2011)

1 1

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Author(s) Anne-Theacuteregravese Auger Mohamed RamyEl-Maarry Olivier Groussin Laurent Jorda Sylvain Bouley Antoine Seacutejourneacute Claire Capanna Sebastian Houmlfner HolgerSierksInstitution(s) 1 Aix-Marseille Universiteacute LaboratoiredAstrophysique de Marseille 2 Laboratoire GEOPS 3Max-Planck-Institut fuumlr Sonnensystemforschung 4Physikalisches Institut University of Bern

50004 ndash Using quantitative analysis to understandthe current and past physical processes that sculptedthe Philae landing siteThe CIVA cameras onboard PHILAE provided the first ever in situimages of the surface of a comet (Bibring et al Science 2015) Thepanorama acquired by CIVA at the landing site on the 67P cometreveals a rough terrain dominated by fractures and agglomerates ofconsolidated materials While the composition of these materials isunknown they provide unique structures to constrain theconditions prevailing at the surface of a comet A quantitativeanalysis of the microscopic structures (grains that look like pebblesand fractures) will be presented The pebble size distribution will becompared to the size distribution of other cometary materials suchas boulders at the touchdown site (Mottola et al Science 2015)boulders surrounding the landing site (Lucchetti et al AampAsubmitted) gt7m sized boulders globally distributed on the comet(Pajola et al AampA 2015) grains collected by the COSIMAexperiment onboard Rosetta (Langevin et al JGR submitted) aswell as population of grains remotely observed in coma and jets ofother comets The nature of the pebbles will be then discussed inrelation to both endogenic and exogenic processes that couldexplain their formation The fractures exhibit two different sizedistributions that are correlated to the texture of the landscapeAmong different physical processes we will evaluate whetherthermal fatigue induced by diurnal temperature variations (Delboet al Nature 2014) could be a mechanism of surficialfragmentation

Author(s) Francois Poulet Alice Lucchetti Jean-PierreBibring Yves Langevin John Carter Marco Delbo PascalEng Brigitte Gondet Laurent Jorda Steacutephane Le Moueacutelic Stefano Mottola Ceacutedric Pilorget Mathieu Vincendon GabrieleCremoneseInstitution(s) 1 University of Padova 2 DLR 3 InstitutdAstrophysique Spatiale 4 LPG-Universiteacute de NantesCNRS 5Observatoire de Marseille 6 UNS-CNRS-Observatoire de la CotedAzur

50005 ndash Temporal morphological changes at thesurface of comet 67PChuryumov-GerasimenkoA key scientific question to understand how comets work andwhether they still contain pristine materials at or near their surfaceis to understand how the nucleus is changing with time and towhich extent activity modifies its surface Rosetta which has beenorbiting comet 67PChuryumov-Gerasimenko since August 2014offers a unique opportunity to tackle this fundamental questionHere we report on temporal morphological changes detected onthe surface of the nucleus of comet 67P by the OSIRIS camerasChanges have been detected in several regions and in particular inthe Imhotep region where they are visible in the form of roundishfeatures that are growing in size from a given location in apreferential direction Terrains bluer than the surroundings appearduring changes suggesting the presence of (water) ice exposed onthe surface

Author(s) Olivier Groussin H Sierks C Barbieri PLamy R Rodrigo D Koschny H Rickman H U KellerInstitution(s) 1 Aix Marseille Universiteacute CNRS LAM(Laboratoire dAstrophysique de Marseille) UMR 7326 2 Centrode Astrobiologia (INTA-CSIC) 3 Department of Physics andAstronomy Padova University 4 Department of Physics andAstronomy Uppsala University 5 Institute of PlanetaryResearch DLR 6 Max-Planck-Institut fuumlrSonnensystemforschung 7 Scientific Support Office EuropeanSpace Agency

50006 ndash The 67P nucleus composition and temporalvariations observed by the OSIRIS cameras onboardRosettaSince August 2014 the comet 67PChuryumov-Gerasimenko hasbeen mapped by the NAC and WAC cameras of the OSIRIS imagingsystem in the 250-1000 nm wavelength range OSIRIS got themost detailed maps at the highest spatial resolution of a cometnucleus surface Here we report on the colors andspectrophotometry of the whole 67P nucleus from images acquiredsince the first Rosetta bound orbits in August 2014 up to the cometperihelion passage Globally the nucleus shows a red spectralbehavior and it has spectrophotometric properties similar to thoseof bare cometary nuclei of primitive D-type asteroids such usJupiter Trojans and of the moderately red Transneptunians Noclear absorption bands have been identified yet in the UV-VIS-NIRrange except for a potential absorption centered at 290 nmpossibly due to SO ice The nucleus shows an important phasereddening with disk-averaged spectral slopes increasing from11(100 nm) to 16(100 nm) in the 13-54deg phase angle rangeOn the basis of the spectral slope we identified three differentgroups of regions characterized by a low medium and highspectral slope respectively The three groups are distributedeverywhere on the nucleus with no evident distinction betweenthe two lobes of the comet The comet southern hemisphere thathas been observed by Rosetta since April 2015 shows a lack ofspectrally red regions associated to the absence of wide spreadsmooth or dust covered terrains Several local bright and spectrallyblue patches have been identified on the nucleus and attributed toexposed water ice on the surface In particular we observed big (gt1500 m ) bright ice rich areas in the southern hemisphere whichcompletely sublimated in a few weeks We see evidence of verybright patches in the NUV-blue region close to the morningshadows that are compatible with the presence of frostsices Thesepatches disappear when fully illuminated by the Sun indicating thatimportant processes of sublimation and recondensation of volatilesare taking place on the nucleus

Author(s) Sonia Fornasier Maria Antonietta Barucci Clement Feller Prasanna JD Deshapriya Antoine Pommerol Luisa Lara Nilda Oklay Mike AHearn Bjorn Davidsson Davide Perna Holger SierksInstitution(s) 1 Department for Astronomy University ofMaryland 2 Department of Physics and Astronomy 3 IAA-CSIC4 LESIA-Observatoire de Paris CNRS Univ Paris Diderot UnivPierre et Marie Curie 5 Max-Planck-Institut fuumlrSonnensystemforschung 6 Physikalisches Institut Univ of Berna

50007 ndash Variegation of active regions on comet67PChuryumov-GerasimenkoSince Rosetta spacecraftrsquos arrival to the comet 67P the OSIRISscientific imager (Optical Spectroscopic and Infrared RemoteImaging System Keller et al 2007) is successfully observing thenucleus with high spatial resolution in the 250-1000 nm rangethanks to set of 26 dedicated filtersWhile 67P has a typical red spectral slope the active areas tend todisplay bluer spectra (Sierks et al 2015 Fornasier et al 2015) Weperformed a spectral analysis of the active areas and derivedspectral characteristics of them possibly indicating the presence ofmaterial enriched in volatilesThe lsquoactivity thresholdsrsquo spectral method (Oklay et al 2015) is usedfor the identification of the active areas In most cases areasdetected with this technique have been later on confirmed as activesources (Lara et al 2015 Lin et al 2015 Vincent et al 2015) bydirect detection of dust jets This technique is therefore able toidentify currently active areas but also predicts which regions ofthe surface are likely to become activated once they receive enoughinsolationAcknowledgements OSIRIS was built by a consortium led by theMax-Planck-Institut fuumlr Sonnensystemforschung GoumlttingenGermany in collaboration with CISAS University of Padova Italythe Laboratoire dAstrophysique de Marseille France the Institutode Astrofisica de Andalucia CSIC Granada Spain the ScientificSupport Office of the European Space Agency Noordwijk TheNetherlands the Instituto Nacional de Tecnica Aeroespacial

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Madrid Spain the Universidad Politechnica de Madrid Spain theDepartment of Physics and Astronomy of Uppsala UniversitySweden and the Institut fuumlr Datentechnik undKommunikationsnetze der Technischen Universitaumlt BraunschweigGermany We thank the Rosetta Science Ground Segment at ESACthe Rosetta Mission Operations Centre at ESOC and the RosettaProject at ESTEC for their outstanding work enabling the sciencereturn of the Rosetta MissionKeller et al 2007 Space Sci Rev 128 433Sierks et al 2015 Science 3471Fornasier et al 2015 AampA published onlineLara et al 2015 AampA published onlineLin et al 2015 AampA published onlineVincent et al 2015 AampA submittedOklay et al 2015 in preparation

Author(s) Nilda Oklay Jean-Baptiste Vincent SoniaFornasier Maurizio Pajola Sebastien Besse Luisa M Lara Maria Antonietta Barucci Stefano Mottola Holger Sierks Antoine Pommerol Nafiseh Masoumzadeh Monica Lazzarin Frank Scholten Frank Preusker Ian HallInstitution(s) 1 CISAS 2 DLR 3 ESA 4 IAA-CSIC 5 LESIA6 MPS 7 Physikalisches Institut Universitaumlt Bern

50008 ndash 67PCG morphological units and VIS-IRspectral classes a RosettaVIRTIS-M perspectiveVIRTIS-M the 025-51 microm imaging spectrometer on Rosetta(Coradini et al 2007) has mapped the surface of 67PCG nucleussince July 2014 from a wide range of distances Spectral analysis ofglobal scale data indicate that the nucleus presents differentterrains uniformly covered by a very dark (Ciarniello et al 2015)and dehydrated organic-rich material (Capaccioni et al 2015) Themorphological units identified so far (Thomas et al 2015El-Maarry et al 2015) include dust-covered brittle materialsregions (like Ash Maat) exposed material regions (Seth)large-scale depressions (like Hatmehit Aten Nut) smooth terrainsunits (like Hapi Anubis Imhotep) and consolidated surfaces (likeHathor Anuket Aker Apis Khepry Bastet Maftet) For each ofthese regions average VIRTIS-M spectra were derived with the aimto explore possible connections between morphology and spectralproperties Photometric correction (Ciarniello et al 2015) thermalemission removal in the 35-5 micron range and georeferencinghave been applied to IF data in order to derive spectral indicatorseg VIS-IR spectral slopes their crossing wavelength (CW) and the32 microm organic material bandrsquos depth (BD) suitable to identify andmap compositional variations Our analysis shows that smoothterrains have the lower slopes in VIS (lt17E-3 1microm) and IR(04E-3 1microm) CW=075 microm and BD=8-12 Intermediate VISslope=17-19E-3 1microm and higher BD=10-128 are typical ofconsolidated surfaces some dust covered regions and Seth wherethe maximum BD=13 has been observed Large-scaledepressions and Imhotep are redder with a VIS slope of 19-21E-31microm CW at 085-09 microm and BD=8-11 The minimum VIS-IRslopes are observed above the Hapi in agreement with thepresence of water ice sublimation and recondensation processesobserved by VIRTIS in this region (De Sanctis et al 2015)Authors acknowledge ASI CNES DLR and NASA financialsupportReferences-Coradini et al SSR 28 529-559 2007-Ciarniello et al AampA in press-Capaccioni et al Science 347 aaa0628 1-4 2015-Thomas et al Science 347 aaa0440 1-6 2015-El-Marry et al AampA in press-De Sanctis et al Nature in press

Author(s) Gianrico Filacchione Fabrizio Capaccioni Mauro Ciarniello Andrea Raponi Maria Cristina De Sanctis Federico Tosi Giuseppe Piccioni Priscilla Cerroni MariaTeresa Capria Ernesto Palomba Andrea Longobardo Alessandra Migliorini Stephane Erard Gabriele Arnold Dominique Bockelee-Morvan Cedric Leyrat Bernard Schmitt Eric Quirico Antonella Barucci Thomas B McCord KatrinStephan David KappelInstitution(s) 1 DLR 2 INAF-IAPS 3 LESIA Obs Paris 4 TheBear Fight Institute 5 Univ Grenoble Alpes CNRS IPAG

50009 ndash Comet 67PChuryumov-GerasimenkoNon-Gravitational Forces Based on its Detailed ShapeNon-gravitational forces caused by sublimation on a cometarynucleus influence its orbital parameters and its rotationalproperties Based on thermal models and rough estimates of thenucleus shape properties such as its mass and density can bederived [1 2] The uncertainty of the nucleus shape influences thequality of the results Changes of the angular momentum of thenucleus rotation are more strongly influenced by details of theshape and surface The long term observations of the nucleus ofcomet 67PChuryumov-Gerasimenko by OSIRIS [3] during therendezvous with ESArsquos Rosetta spacecraft result in a very detailedshape model [3] We use a shape model with gt 10 facets tosimulate the distributed forces due to sublimation and to calculatetheir exerted torques The determination of the overall activity andits spatial and timely distribution over the nucleus remains a majorchallenge Early observations revealed that the rotation period hadchanged from its last perihelion passage in 2009 [4] The detailedshape model along with thermal modeling makes it possible tocalculate the diurnal activity of the facets [6 7] The net torqueintegrated over the whole surface causes a change in the angularmomentum We also calculate the forces acting on the motion ofthe nucleus This can be monitored by determinations of thespacecraft positions during the Rosetta mission We will compareour results with the traditional approach to calculate thenon-gravitational forces [8][1 2] Davidsson B J R amp Gutieacuterrez P J Icarus 168 392 2004Icarus 176 453 2005[3] H U Keller C Barbieri P Lamy H Rickman R RodrigoK-P Wenzel H Sierks M ArsquoHearn F Angrilli M Angulo et alSSR 128 (1-4) 433ndash506 2007[4] Preusker F Scholten F Matz K-D et al Astronomy ampAstrophysics accepted 2015[5] S Mottola S Lowry C Snodgrass P Lamy I Toth et al AampA569 L2 Sept 2014[6] H U Keller S Mottola B Davidsson S Schroumlder Y SkorovE Kuumlhrt et al AampA in press[7] H U Keller S Mottola Y V Skorov and L Jorda Astronomyand Astrophysics Letter 2015[8] B G Marsden Z Sekanina and D K Yeomans AstronomicalJournal 78 211 Mar 1973

Author(s) Horst Uwe Keller Stefano Mottola YuriSkorov Bjoumlrn Davidsson Pedro Gutieacuterrez Laurent Jorda Lucie MaquetInstitution(s) 1 Aix Marseille Universiteacute CNRS LAM 2Department of Physics and Astronomy Uppsala University 3Deutsches Zentrum fuumlr Luft- und Raumfahrt (DLR) Institut fuumlrPlanetenforschung Asteroiden und Kometen 4 Instituto deAstrofiacutesica de Andaluciacutea (CSIC) 5 Max-Planck-Institut fuumlrSonnensystemforschung 6 Scientific Support Office EuropeanSpace Astronomy CentreESA

501 ndash Extrasolar Planets Discovery andDynamics50101 ndash Discovery and follow-up of 51 Eri b adirectly-imaged Jupiter-like exoplanet and status ofthe GPIES campaignDirectly detecting thermal emission from young extrasolar planetsallows measurement of their atmospheric composition gravity andluminosity which is influenced by their formation mechanism The

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6

158

Gemini Planet Imager Exoplanet Survey (GPIES) is targeting 600young nearby stars using the GPI instrument The star 51 Eridani(51 Eri) was chosen as an early target for the survey due to its youthand proximity We discovered a planet orbiting the ~20 Myr-oldbeta Pic moving group member star 51 Eridani at a projectedseparation of 13 astronomical units (Macintosh et al Science2015) Near-infrared observations show a spectrum with strongmethane and water vapor absorption Modeling of the spectra andphotometry yields a luminosity of LL =16-40 times 10 and aneffective temperature of 600-750 K For this age and luminosityldquohot-startrdquo formation models indicate a mass twice that of JupiterThis planet also has a sufficiently low luminosity to be the firstdirectly imaged exoplanet to be consistent with the cold-start coreaccretion process that may have formed JupiterFollow-up observations scheduled in Fall 2015 will allow us toconstrain the orbit of this exoplanet and derive more informationon its atmosphere These new data and additional interestingtargets will be presented and discussedSupported by grants from the National Science FoundationAST-1411868 (BM KF JP AR) AST-0909188 and 1313718 (JRGPK RDR JW) AST-1313718 (MPF and GD) and AST-1405505Supported by grants from NASA NNX14AJ80G (BM FM EN MP)NNH15AZ591 (DS MM) NNX15AD95G (JRG PK) NNX11AD21G(JRG PK) and NNH11ZDA001N (SM RP) JR RD and DLacknowledge support from the Fonds de recherche du QuebecPortions of this work were performed under the auspices of theUS Department of Energy by Lawrence Livermore NationalLaboratory under Contract DE-AC52-07NA27344

Author(s) Franck Marchis Eric L Nielsen Sarah Blunt Julien Rameau Travis Barman Robert J De Rosa QuinnKonopacky Mark S Marley Christian Marois LaurentPueyo Abhijith Rajan Jason J Wang Bruce Macintosh James R GrahamInstitution(s) 1 Kavli Institute for Particle Astrophysics andCosmology Stanford University 2 Center for Astrophysics andSpace Sciences University of California 3 Department ofAstronomy UC Berkeley 4 Institut de Recherche sur lesExoplanegravetes Deacutepartment de Physique Universiteacute de Montreacuteal 5Lunar and Planetary Laboratory University of Arizona 6 NASAAmes Research Center MS 245-3 7 National Research Council ofCanada Herzberg 8 School of Earth and Space ExplorationArizona State University 9 SETI Institute 10 Space TelescopeScience Institute

50102 ndash The SuPerPiG search for short period planetsin the K2 datasetPlanets with orbital periods of less than a day present realchallenges to theories of planet formation and evolution and yetnumerous objects with periods as short as a few hours have beenfound So close to their host stars that some are activelydisintegrating these planets origins remain unclear and evenmodified models for planet formation and evolution withsignificant inward migration have trouble accounting for theirperiods They thus provide an important probe of the innermostregion of the protoplanetary disk We report on the ongoing effortsof the Short-Period Planets Group (SuPerPiGhttpwwwastrojackcomresearchsuperpig) to find additionalshort-period planets in the K2 Mission using the light curveproducts produced by the Vanderburg and Johnson k2sff pipeline(Vanderburg amp Johnson 2014 httpsarchivestscieduprepdsk2sff) Preliminary results from Campaign 2 includingaccounting for a 6-hour pseudo transit signal introduced by theKepler spacecraft thruster re-pointing will be presented

Author(s) Elisabeth R Adams Brian JacksonInstitution(s) 1 Boise State University 2 Planetary ScienceInstitute

50103 ndash A Quantitative Criterion for Defining PlanetsThe IAU definition of planet needs improvement because it isneither quantitative nor general The current definition appliesonly to solar system bodies and does not allow for the classificationof exoplanets The current definition can also be misunderstood or

misconstrued because of its qualitative nature (eg has clearedthe neighbourhood around its orbit)A simple metric can be used to determine whether a planet orexoplanet can clear its orbital zone during a characteristic timescale such as the lifetime of the host star on the main sequenceThis criterion requires only estimates of star mass planet massand orbital period making it possible to immediately classify 99of all known exoplanets All 8 planets and all classifiable exoplanetssatisfy the criterionI will describe the development of the metric and apply it to solarsystem bodies exoplanets and pulsar planets I will then show howthis metric could be used to quantify generalize and simplify thedefinition of planet A preprint is available at httparxivorgabs150706300

Author(s) Jean-Luc MargotInstitution(s) 1 University of California Los Angeles

50104D ndash Dynamical Heating Induced by DwarfPlanets on Cold Kuiper Belt-like Debris DisksWith the use of long-term numerical simulations we study theevolution and orbital behavior of cometary nuclei on cold Kuiperbelt-like debris disks under the gravitational in uence of dwarfplanets (DPs) we carry out these simulations with and without thepresence of a Neptune-like giant planet This comprehensive studyshows that in the absence of a giant planet 10 DPs are enough toinduce strong radial and vertical heating on the orbits of beltparticles On the other hand the presence of a giant planet close tothe debris disk acts as a stability agent reducing the radial andvertical heating With enough DPs even in the presence of aNeptune-like giant planet some radial heating remains thisheating grows steadily re-lling resonances otherwise empty ofcometary nuclei This seems to work as a plausible secular processable to provide material that after falling into the resonances withthe giant through resonant chaotic diusion could sustain a rate ofnew comets spiraling into the inner planetary system

Author(s) Marco Antonio Muntildeoz-Gutieacuterrez BarbaraPichardo Mauricio Reyes-Ruiz Antonio PeimbertInstitution(s) 1 Instituto de Astronomiacutea UNAM

50105 ndash Masses of the Five Small Planets AroundKepler-80Kepler has discovered hundreds of multi-transiting systems whichhold tremendous potential both individually and collectively forunderstanding the formation and evolution of planetary systemsMany of these systems are quite compact containing 3-7 relativelysmall planets with periods less than 100 days these are known asSystems with Tightly-packed Inner planets or STIPs One ultra-compact STIP is KOI-500Kepler-80 a planetary systemcontaining five transiting planets ranging in size from 15 to 28times the radius of the Earth that orbit in a tightly-packedconfiguration with periods between 1 and 10 days In addition to itsclose packedness the outer four planets are in a unique dynamicalconfiguration with two interconnected three-body resonancesUsing transit timing variations (TTVs) caused by the gravitationalperturbations we perform a fully self-consistent dynamicalanalysis of the system finding best-fit masses for the outer fourplanets to be each around five Earth masses We also performedextensive testing of synthetic systems and have determined thateccentricities cannot be reliably detected but that assumingcircular orbits does not significantly affect the mass estimates Wewill present the inferred properties for Kepler-80 and discuss theseresults in context of (ultra-compact) STIPs and the small planetmass-radius relation

Author(s) Mariah G MacDonald Darin Ragozzine DanielC FabryckyInstitution(s) 1 Florida Institude of Technology 2 Universityof Chicago

50106 ndash The search for ExomoonsThere are hundreds of Exoplanets which the data are available fordynamical investigation There is a wealth of diversity of

⦿ -6

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2 1

1

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Exoplanets types and the expectation in finding our Earth-livingconditions in another planet motivates the search for Extra-solarplanets A satellite around a planet in the habitable zone would inaddition contributes to keep the climate The main objective of thiswork is to provide a list of the best planet candidates to harbor adetectable exomoon by the current telescopes such as the Keplermission so as to guide the searches The planets were sorted outinto class groups according to their masses and radii For eachplanet we have calculated the stability region where an exomooncan exist for a long period of time The outer boundary isdetermined from the critical stability limit obtained from dynamicalnumerical simulation of a restrict three body problem whereas theinner boundary is given by the Roche limit Moreover the satellitehas to be bigger than a certain value to be detected in the noisytransit lightcurves of the CoRoT and Kepler missions Wedetermined the maximum radius of the stability zone for severalplanet types and proved that the relation reported in a previouswork by Domingos et al (2006) only for hot Jupiters is valid for allplanet class Considering moons of different densities (iceice-rock rock rock-iron iron) able to survive within the calculatedstability region and with a minimum detectable size we derived alist of the best 38 planet candidates with orbiting moons A list ofthe top ten planet candidates where exomoons should be searchedwithin the Kepler transit lightcurves is given These planets couldharbor big enough moons to be detected above the data noise forany moon composition

Author(s) Ana Helena Fernandes Guimaratildees AdrianaBenetti Marques Valio Luis Ricardo Moretto Tusnski ErnestoVieira-NetoInstitution(s) 1 INPE - Instituto Nacional de PesquisasEspaciais 2 Mackenzie Presbyterian University 3 UNESP -University of State of Satildeo Paulo

50107 ndash The Primordial Destruction of Moons aroundGiant Exoplanets through Disk-Driven PlanetaryMigrationThe extensive array of satellites around Jupiter and Saturn makes itreasonable to suspect that similar systems of moons might existaround giant extrasolar planets Observational surveys haverevealed a significant population of such giant planets residing atdistances of about 1 AU leading to speculation that some of theseexomoons might be capable of maintaining liquid water on theirsurfaces Accordingly many recent efforts have specifically huntedfor moons around giant exoplanets Owing to the lack of detectionsthus far it is worth asking whether certain processes intrinsic toplanet formation might lead to the loss of moons Here wehighlight that giant planets are thought to undergo inwardmigration within their natal disks and show that the very process ofmigration naturally captures moons into a so-called evectionresonance Within this resonance the lunar orbits eccentricitygrows until the moon is lost either by collision with the planet orthrough tidal disruption Whether moons survive or not is criticallydependent upon where the planet began its inward trek In thisway the presence or absence of exomoons can inform us on theextent of inward migration for which no reliable observationalproxy currently exists

Author(s) Christopher Spalding Konstantin Batygin FredC AdamsInstitution(s) 1 California Institute of Technology 2University of Michigan

50108 ndash Tidal Decay and Disruption of GaseousExoplanetsMany gaseous exoplanets in short-period orbits are on the verge ofRoche-lobe overflow and observations along with orbital stabilityanalysis show tides probably drive significant orbital decay Thusthe coupled processes of orbital evolution and tidal disruptionlikely shape the observed distribution of close-in exoplanets andmay even be responsible for producing the shortest-period solidplanets However the exact outcome for an overflowing planetdepends on its internal response to mass loss and variable stellarinsolation and the accompanying orbital evolution can act to

enhance or inhibit the disruption process The final orbits of thedenuded remnants of gas giants may be predictable from theirmass-radius relationship and so a distinctive mass-periodrelationship for some short-period solid planets may provideevidence for their origins as gaseous planets In this presentationwe will discuss our work on tidal decay and disruption of close-ingaseous planets using a new model that accounts for the fact thatshort-period planets have hot distended atmospheres which canresult in overflow even for planets that are not officially in Rochelobe contact We will also point out that the orbital expansion thatcan accompany mass transfer may be less effective than previouslyrealized because the resulting accretion disk may not return all ofits angular momentum to the donor as is usually assumed Both ofthese effects have bee incorporated into the fully-featured androbust Modules for Experiments in Stellar Astrophysics (MESA)suite

Author(s) Brian K Jackson Phil Arras Emily Jensen Sarah Peacock Pablo Marchant Kaloyan PenevInstitution(s) 1 Boise State University 2 Princeton University3 Universitaumlt Bonn 4 University of Arizona 5 University ofVirginia

502 ndash Jovian Planet MagnetospheresAurorae and Atmospheres50201 ndash Transport of magnetic flux in Saturnrsquos innermagnetosphereThe dynamics of the Saturnian magnetosphere which rotatesrapidly with an internal plasma source provided by Enceladusqualitatively resembles those of the jovian magnetosphere poweredby Io The newly added plasma is accelerated to the corotationspeed and moves outward together with the magnetic flux In thenear tail region reconnection cuts the magnetic flux reconnects itinto plasma-depleted inward moving flux tubes and outwardmoving massive plasmoids The buoyant empty tubes then convectinward against the outward flow to conserve the total magnetic fluxestablished by the internal dynamo In both jovian and saturnianmagnetospheres flux tubes with enhanced field strength relative totheir surroundings are detected in the equatorial region Recentobservations show that there are flux tubes with reduced fieldstrength off the equator in the saturnian magnetosphere Tounderstand the formation mechanism of both types of flux tubeswe have surveyed all the available 1-sec magnetic field data fromCassini The systematic statistical study confirms the differentlatitudinal distributions of the two types of flux tubes In additionenhanced-field flux tubes are closer to the planet whilereduced-field flux tubes can be detected at larger distances bothtypes of flux tubes become indistinguishable from the backgroundmagnetic flux inside an L-value of about 4 the local timedistribution of both types of flux tubes are similar and they containabout the same amount of magnetic flux Therefore the two typesof flux tubes are the same phenomena with differentmanifestations in different plasma environments When thesurrounding plasma density is high (near the equator and closer tothe plasma source region) the flux tubes are compressed and haveenhanced field strength inside while in the low-plasma densityregion (off the equator and further from the plasma source region)the flux tubes expand and have reduced field strength inside

Author(s) Christopher T Russell H R Lai H Y Wei YD Jia M K DoughertyInstitution(s) 1 Imperial College London 2 UC Los Angeles

50202 ndash Ground-based and Space-based Observationsof Jovian Mid-Infrared Aurora During the CassiniFlyby of Jupiter 2000ndash2001We report on a re-examination and re-analysis of hydrocarbonemission spectra collected from Jupiter using ground-basedultra-high spectral resolution infrared heterodyne spectroscopy(IRHS) and space-based Fourier transform spectroscopy (FTS)from the Cassini spaceraft during its flyby of Jupiter in 2000-2001Auroral emission by ethane was measured from Earth with the

22 1

3

1 12

1 5 14 3 2

2 2 22 1

160

Heterodyne Instrument for Planetary Wind and CompositionHIPWAC in December 2000 and in February 2001 Shapes ofindividual emission lines of ethane near 12 microm wavelength weremeasured from the polar regions of Jupiter at spectral resolvingpower of 1000000 These observations were conducted in concertwith scheduled observations of the Jovian auroral region by theCassini Composite Infrared Spectrometer (CIRS) at resolvingpowers of ~2000 before and after closest approach on December30 2000 The HIPWAC measurements complement CIRS broadspectral and spatial coverage with its uniquely high spectralresolution and spatial discrimination from the ground comparableto that at Cassinirsquos closest approach Fully resolved ethane linemeasurements retrieve both temperature and ethane abundanceinformation at the north and south auroral hot spots CIRS data atcoarser spectral resolution provide extended spatial distributionscovering a broad spectral band including abundances and auroralresponse of several hydrocarbon constituents in the 8ndash13micrometer spectral region (ethane methane ethylene andacetylene) Preliminary studies of both data sets reveal temporalvariability and low enhancement of the thermal infrared auroraeduring the flyby compared to other periods observed Analyses ofboth data sets will be reported and retrievals will be comparedResults will be useful to interpreting the Juno mission since thiswork provides complementary information and diagnostics tostudy Jupiter in a spectral region and altitude range not directlyprobed by Juno

Author(s) Theodor Kostiuk Tilak Hewagama Timothy ALivengood Kelly E Fast Gordon L Bjoraker Ronald Carlson Frank Schmuumllling Conor A NixonInstitution(s) 1 Catholic University of America 2 DLR 3NASA HQ 4 NASAs GSFC 5 University of Maryland

50203 ndash Jupiter Climatological Database fromFrequent 5-25 microm Mid-IR Spectral Mapping usingIRTFTEXESWe report on the development of a long-term Jovian ClimatologicalDatabase (JCliD) to explore variability in Jupiterrsquos atmospherictemperatures winds clouds and compositionndash from long-termseasonal changes to short-term major upheavals Radiometricallycalibrated spectral scan maps of Jupiter have been regularlyobtained using the TEXES instrument (Texas Echelon crossEchelle Spectrograph Lacy et al 2002 PASP 114 p153-168)between 2012 and 2015 Ten settings between 5 and 25 microm (10-20cm wide settings at spectral resolutions of 2000-10000) wereselected to be sensitive to jovian temperatures (via H CH andCH D) tropospheric phosphine and ammonia tropospheric hazeopacity and stratospheric hydrocarbons ethane and acetyleneDiffraction-limited spatial resolutions of 06-16rdquo were achievedObservations over consecutive nights allow the creation of fullspatial maps for comparison with the visible light record revealingephemeral stratospheric wave activity NEB hotspots heating atthe northern auroral oval and complex thermal signaturesassociated with tropospheric vortices waves and barges Fullspectra are inverted via the NEMESIS retrieval algorithm (Irwin etal 2008 JSQRT 109 p1136-1150) to map temperatures at multiplealtitudes (1-600 mbar) winds aerosol opacity and gaseouscomposition The spatial and spectral resolutions of the resultingmaps surpass those obtained during the Cassini flyby of Jupiter in2000 and permit temporal interpolation to understand theenvironmental conditions related to the emergence and evolutionof discrete features In December 2014 we find warmertemperatures in the northern stratosphere (a seasonal effect in latenorthern summer despite Jupiterrsquos small axial tilt) a hemisphericasymmetry in the tropospheric PH distribution due to variationsin the vigour of vertical mixing and photolytic shielding elevatedPH aerosols and NH in the equatorial zone (EZ) related toequatorial uplift elevated aerosol opacity in the northern andsouthern tropical zones (NTrZ and STrZ) and enhanced PH andaerosols over the Great Red Spot Maps of retrieved properties willbe assembled as a database (JCliD) to aid in the interpretation ofJuno data during 2016-2017

Author(s) Leigh N Fletcher Glenn S Orton Thomas KGreathouse James Sinclair Patrick GJ Irwin Rohini SGiles Therese Encrenaz Pierre DrossartInstitution(s) 1 LESIA Observatoire de Paris 2 NASA JetPropulsion Laboratory 3 Southwest Research Institute 4University of Leicester 5 University of Oxford

50204 ndash Are Brown Barges the Deserts of the UpperJovian AtmosphereSince the descent of the Galileo probe into one of Jupiterrsquos 5-micromhot spots these regions have been characterized as the driest andclearest regions on the planet We are presenting evidence that thisgeneralization could be premature at least for Jupiterrsquos uppertroposphere Diffraction-limited mid-infrared images of Jupitertaken from the Subaru Telescope using the COMICS instrumentthe Very Large Telescope (UT3) using the VISIR instrument andthe Gemini South Telescope using the T-ReCS instrument resolveregions with the highest brightness anywhere on the planet atwavelengths near 98-105 microm a region sensitive to the abundanceof ammonia gas above its condensation level These brightnessesare so high that they require ammonia abundances that are manytimes lower than anywhere else on the planet A similar drop of theoptical thicknesses of clouds near the ammonia-gas condensationlevel is required diagnosed using 87-89-microm radiances Thesefeatures are also detected but not spatially resolved in observationsobtained at NASArsquos Infrared Telescope Facility using the MIRSIimager and the TEXES scanning spectrometer Most are locatedalong the northern edge of the North Equatorial Belt and areassociated with cyclonic features known as ldquobrown bargesrdquo Theyare not associated with detectable changes in upper-tropospherictemperatures requiring convective activity to take place at depthswith very rapid dynamical readjustment Regions bright at 8-10 micromare not always bright in the deep 5-microm window implying that somebrown barges are clear of condensate gases and clouds only downto 06 bars but others are clear down to 2-3 bars a possibleconsequence of observing them in different phases of their ldquolifecyclerdquo These other discrete features and broader regions will bethe objects of intensive investigations by the Juno mission andassociated Earth-based observational support in 2016 to 2018

Author(s) Glenn S Orton James Sinclair Leigh Fletcher Takuya Fujiyoshi Padma Yanamandra-Fisher John Rogers Patrick Irwin Thomas Greathouse Raiyan Seede JasonSimon Marian Nguyen Matthew LaiInstitution(s) 1 British Astronomical Association 2 CaliforniaInstitute of Technology 3 California State University 4 JPL 5Southewest Research Institute 6 Space Science Institute 7 SubaruTelescope 8 University of Leicster 9 University of Oxford 10University of Paris Sorbonne Abu Dhabi

50205 ndash First results from the Hubble OPALProgram Jupiter in 2015The Hubble 2020 Outer Planet Atmospheres Legacy (OPAL)program is a Directors Discretionary program designed to generatetwo yearly global maps for each of the outer planets to enable longterm studies of atmospheric color structure and two-dimensionalwind fields This presentation focuses on Jupiter results from thefirst year of the campaign Data were acqured January 19 2015 withthe WFC3UVIS camera and the F275W F343N F395N F467MF502N F547M F631N F658N and F889N filters Global mapswere generated and are publicly available through the High LevelScience Products archive httpsarchivestscieduprepdsopalUsing cross-correlation on the global maps the zonal wind profilewas measured between +- 50 degrees latitude and is in family withVoyager and Cassini era profiles There are some variations in midto high latitude wind jet magnitudes particularly at +40degand -35degplanetographic latitude The Great Red Spot continues to maintainan intense orange coloration as it did in 2014 However theinterior shows changed structure including a reduced core andnew filamentary features Finally a wave not previously seen inHubble images was also observed and is interpreted as a baroclinicinstability with associated cyclone formation near 16deg N latitude Asimilar feature was observed faintly in Voyager 2 images and isconsistent with the Hubble feature in location and scale

4 55 3 4 1

2 4

-1

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3

3 3

3

4 23 2 5

5 1 1

4 4 87 6 1

9 5 102 3 3

161

Author(s) Amy A Simon Michael H Wong Glenn SOrtonInstitution(s) 1 Jet Propulsion LaboratoryCaltech 2 NASAsGSFC 3 University of California at Berkeley

50206 ndash Ammonium Hydrosulfide Coloring JupitersCloudsThe appearance and composition of Jupiterrsquos Great Red Spot (GRS)have been studied for over a century yet there still is no consensusfor what is causing the GRSrsquos color As the GRS is believed tooriginate in tropospheric clouds it seems likely that one or morecloud components may contribute to the GRSs color Recently wehave begun to investigate whether either ammonium hydrosulfide(NH SH) a predicted cloud component or its radiation-chemicalproducts can produce color andor an ultraviolet-visible spectrumsimilar to what has been observed on Jupiter via remote sensing(eg Simon et al 2015) Our initial experiments relied on infraredspectroscopy to quantify the radiolytic and thermal stability ofNH SH and to identify the new chemical products formed duringMeV ion irradiation (Loeffler et al 2015) This DPS presentationwill cover some of our most recent results detailing the ultraviolet-visible spectral and color changes observed during irradiation andpost-irradiation warming of NH SH ices This work is funded byNASArsquos Outer Planets and Planetary Atmospheres programs

Author(s) Mark J Loeffler Reggie L Hudson Nancy JChanover Amy A SimonInstitution(s) 1 NASA GSFC 2 New Mexico State University

50207 ndash Deriving Saturns Zonal Winds from CassiniRadio OccultationsTracking cloud features from visible images have provided detailedmaps of the meridional variation of the mean zonal winds on thegiant planets including Saturn Filters at different wavelengths canprovide information on the vertical structure of the zonal windsbut that is approximate and the altitudes of winds observed with agiven filter generally vary with location because cloud heights doRadio occultations provide vertical profiles of refractivity pressureand temperature vs altitude Zonal winds can be derived from theassumption of gradient wind balance which relates the zonal windto the change of geopotential height with latitude along an isobarOccultations have the advantage that vertical profiles of winds canbe obtained in the troposphere and stratosphere There arehowever complicating factors In general the meridionaldistribution of occultation soundings is limited and unevenlydistributed Moreover one needs to know the geometry of theocculting atmosphere to correctly account for the path of therefracted radio signal The zonal winds matter because they distortisobaric surfaces For example an inversion that includes Saturnsoblateness from uniform rotation based on the Voyager System IIIperiod would yield equatorial temperature profiles that are shiftedby ~ 2 K relative to one that also includes the differential rotationassociated with the cloud-tracked zonal winds In retrieving verticalprofiles of atmospheric variables from occultation soundings onealso needs an additional symmetry assumption to make theinversions tractable Typically one uses the zonal winds based oncloud-tracking studies and assumes they are axisymmetric andbarotropic so that both the gravitational and centrifugal forces arederivable from a potential and the surfaces of constantgeopotential height pressure and temperature coincide Thisforms the basis for an iterative approach The pressures andtemperatures so retrieved from the occultation soundings are notbarotropic but the zonal winds derived from the gradient windequation can be added to the cloud-tracked winds used in theinversions We discuss Saturns equatorial soundings as anillustration

Author(s) F Michael Flasar Paul J SchinderInstitution(s) 1 Cornell University 2 NASAs GSFC

50208 ndash A Ring-lsquoRainrsquo influence for Saturnrsquos CloudAlbedo and Temperatures Evidence Pro or Con fromVoyager HST and CassiniJ E P Connerney [Geophys Res Lett 13 773-776 1986] pointed

out that lsquolatitudinal variations in images of Saturnrsquos disk upperatmospheric temperatures and ionospheric electron densities arefound in magnetic conjugacy with features in Saturnrsquos ring planersquoand proposed lsquothat these latitudinal variations are the result of avariable influx of water transported along magnetic field lines fromsources in Saturnrsquos ring planersquo Observations of H support aring-ionosphere connection [ODonoghue et al Nature 496 74442013] What about cloud albedo and temperature Connerneyattributed a hemispheric asymmetry in haze and temperature to anasymmetry in water flux and predicted that lsquothe presently-observednorth-south asymmetry (upper tropospheric temperaturesaerosols) will persist throughout the Saturn yearrsquo We can now testthese ideas with data from the Cassini mission from the HubbleSpace Telescope and from ground-based observations Analyses ofground-based images and especially Hubble data established thatthe hemispheric asymmetry of the aerosol population does changeand seasonal effects are dominant although non-seasonalvariations are also observed [Karkoschka and Tomasko Icarus 179195-221 2005] Upper tropospheric temperatures also vary asexpected in response to seasonal forcing [Fletcher et al Icarus208 337-352 2009] Connerney also identified dark bands inVoyager Green-filter images on magnetic conjugacy with the E ringand edges of the A and B rings In Cassini Green-filter images thereis some correspondence between dark bands and ring features inmagnetic conjugacy but collectively the correlation is not strongCassini 727-nm methane band images do not suggest depletion ofaerosols in the upper troposphere at ring edge magnetic conjugacylatitudes as proposed by Connerney We conclude that ring raindoes not have a significant influence on upper troposphericaerosols and temperatures on Saturn Part of this work wasperformed by the Jet Propulsion Lab Calif Institute ofTechnology

Author(s) Robert A West Liming LiInstitution(s) 1 JPL 2 Univ of Houston

50209D ndash Determining the vertical extent of JupitersGreat Red Spot with the Juno gravity measurementsThe NASA Juno mission is due to arrive at Jupiter in July 2016 Weexplore the possibility of inferring the depth of Jupiterrsquos biggestvortex the Great Red Spot (GRS) by determining its gravitationalsignature with the onboard gravity experiment consideringdifferent possible scale heights for the vortex We estimate thestrength of the gravity signal coming from the vortex using anidealized dynamical model for the atmosphere of the giant planetThe gravity anomaly is then compared to the expected accuracy inthe retrieval of the surface gravity at the GRS location obtainedwith numerical simulations of the Doppler data inversion based onthe expected trajectory of the spacecraft Starting from observationsof the planets velocity vectors at the cloud level we propagate theprofiles along coaxial cylinders parallel to the spin axis and explorea wide range of decay scale heights in the radial directionAssuming the large scale vortex dynamics are geostrophic andtherefore thermal wind balance holds the density anomalydistribution due to Jupiters winds can be derived from the velocitymaps The novelty of this approach is in the integration of thermalwind relations over a three-dimensional grid and in the inclusionof the observed meridional velocity as measured during the Cassiniflyby of Jupiter The introduction of longitudinal perturbations tothe mean zonal flows gives rise to fluctuations in the tesseralspherical harmonics of Jupiters gravitational potential We showthat the deeper the penetration of the jets the stronger is thegravity signal coming from the GRS On the other hand the largerthe mass involved in the planets atmospheric motion the higherare the degree and order of the spherical harmonic expansion ofJupiters gravity field needed to fit the simulated Doppler data Weshow that the mass anomaly associated with the Great Red Spot isdetectable by the Juno gravity experiment if the winds penetrate atdepth of 2000 km below the cloud level of Jupiter and that thelarge mass involved with deep winds does not render much theability to measure the feature

2 31

4

4

4

1 12 1

2 1

3+

1 2

162

Author(s) Marzia Parisi Eli Galanti Stefano Finocchiaro Luciano Iess Yohai KaspiInstitution(s) 1 Sapienza Universitagrave di Roma 2 WeizmannInstitute of Science

503 ndash Comet 67PC-G -- Coma andEnvironment50301 ndash One year at the comet highlights from theROSINA instruments on the composition andevolution of the cometary comaAfter one year in the close vicinity of comet 67PChuryumov-Gerasimenko we report on the most surprising results from theRosetta Orbiter Sensor for Ion and Neutral Analysis (ROSINA) onRosetta which is analysing the volatile composition of the cometarycoma since more than 15 months Several species like N and Arwere detected for the first time in a cometary coma others havebeen detected before in long period but not in Jupiter familycomets There are significant amounts of long carbon chainmolecules Many of them are probably related to dust We will givean overview on the inventory of volatile and less volatile speciesThe coma is quite heterogeneous and the relative abundances varyby factors between summer and winter hemisphere The evolutionof the abundances with heliocentric distances and solarillumination will be discussed

Author(s) Kathrin Altwegg Hans Balsiger UrsinaCalmonte Seacutebastien Gasc Myrtha Haumlssig Leacutena LeRoy Annette Jaumlckel Martin Rubin Peter Wurz Chia-Yu Tzou Urs Mall Bjoumlrn Fiethe Johan de Keyser Jean-JacquesBerthelier Henri Regraveme Tamas Gombosi Steven FuselierInstitution(s) 1 BIRA 2 Center for Space and Habitability 3IRAP 4 LATMOS 5 Max-Planck Insitut fuumlr Sonnenphysik 6SwRI 7 Technische Universitaumlt Braunschweig 8 University ofBern 9 University of Michigan

50302 ndash Comet 67P Nucleus-Coma Interaction andComa Structure Observed with RosettaMIROThe Microwave Instrument on the Rosetta Orbiter (MIRO)operating at frequencies near 190 GHz and 562 GHz has beenobserving Comet 67P nucleus thermal emissions and comamolecular lines since May 2014 As Comet 67P approachesperihelion in its orbit around the Sun MIRO witnesses that thenucleus heats up and emits more volatiles creating a densecomplex and rich coma structure In order to study nucleus-comainteractions and coma structure and evolution MIRO has usedspecially designed scan patterns called ldquoInner Coma Maprdquo andldquoNucleus Gas Emissionrdquo which cover the nucleus limb and innercoma region in detail In this paper we will present the MIROmolecular line measurements with those scan patterns fromJanuary 2015 to August 2015 We have analyzed the linemeasurements with a non local-thermal-equilibrium molecularradiative transfer model and an optimal estimation method in orderto retrieve nucleus and coma parameters such as outgassing ratecolumn density expansion velocity and gas kinetic temperatureAlong with the line analysis retrieval results we will discuss theimplication of the results on nucleus-coma interactions comastructure and their temporal evolutions

Author(s) Seungwon Lee Paul von Allmen Samuel Gulkis Mathieu Choukroun Mark Hofstadter Margaret A Frerking Crovisier Jacques Gerhard BeaudinInstitution(s) 1 Jet Propulsion Laboratory 2 LERMAObservatoire de Paris 3 LESIA-Observatoire de Paris

50303 ndash Observed changes in the physicalenvironment and chemistry in the inner coma of67PChuryumov-GerasimenkoThe Optical Spectroscopic and Infrared Remote Imaging System(OSIRIS) on board Rosetta consists of two bore-sighted cameras(Keller et al 2007) Its Wide Angle Camera includes narrow-bandfilters to image gaseous emission by CS OH NH CN NH Na

and [O I]OSIRIS monitored gas about once every two weeks for heliocentricdistances greater than 2 AU and weekly afterward Images werecalibrated using the OSIRIS pipeline (Tubiana et al 2015) andfurther processed to remove the continuum flux and the emissionfrom other molecules with lines that fall within the narrowbandfiltersrsquo passbandsMany collimated jets are visible in the continuum images (Lara etal 2015 Lin et al 2015) Those jets are not present in the gasimages The morphology of the gas images is either focused in aprojected cone (OI CN) or diffuse and roughly isotropic (OH NHCS NH ) We interpret the first as the signature of promptemission (where fragmentation of a molecule released from thenucleus directly produces a radical in an excited state) and thesecond as that of excitation of fragments species after they wereformedSurprisingly up to the spring of 2015 all measured surfacebrightnesses are more than 10x higher than can be accounted forby formation and excitation processes as understood from remotesensing of comets This changed in the summer of 2015 andcurrent measurements are consistent with photodissociation andfluorescence rates This change reflects the transition of 67P from adistant comet with extremely low gas production rates to conditionsunder which comets are normally observed

Author(s) Dennis Bodewits Luisa M Lara FiorangelaLaForgia Michael F AHearn Joerg Knollenberg MonicaLazzarin Zhing-Yi Lin Xian ShiInstitution(s) 1 Deutsches Zentrum fuumlr Luft- und Raumfahrt 2Institute for Space Science National Central University 3Instituto de Astrofisica de Andalucia-CSIC 4 Max-Planck Institutfuumlr Sonnensystemforschung 5 University of Maryland 6University of Padova

50304 ndash Water and carbon dioxide investigation inthe inner coma of 67PChuryumov-GerasimenkoThe study of 67PCG coma environment is one of the primaryscientific goals of the VIRTIS experiment aboard ESA RosettamissionIn the present work results of 74 observations acquired byVIRTIS-M IR channel in the 1-5 μm spectral range from 8 to 14April 2015 are discussed In this time 67PCG was at heliocentricdistance of 19 AU and the coma activity was monitored for about10 full comet rotations This allows one to tentatively correlate gasdistribution with active areas on the nucleus and to disentangle gasemissions from dustVibrational emission lines of H O and CO at 267 and 427 μmrespectively are identified by VIRTIS-M imaging channel andmapped from the surface up to about 10 km altitude with a spatialresolution of approximately 40 mpxThe maximum H O emission is mainly concentrated aboveAten-Babi and Seth-Hapi active regions which are located on theneck connecting the two principal lobes The CO column densityis quite poor in the neck region while diffuse emission is clearabove the small and great lobe regions These observations confirmthe anti correlation between these two main species as alreadynoticed by Bockeleacutee-Morvan et al (2015) and Haumlssig et al (2014)Column density of both species decreases with altitude with theCO2 distribution decreasing more rapidly than the H2O TheH OCO ratio which increases with the altitude varies from 187close to the nucleus to 308 at 2-3 km above the nucleus Thesevalues refer to the equatorial region calculated considering all thelongitudes Gas emission is maximum in the afternoon quadrantfrom 12 LST to 18 LSTVIRTIS-M has revealed with unprecedented spatial resolution thedistribution of gaseous species around a cometary nucleus andcorrelated the emissions with surface-active areas altitude abovethe nucleus and local time Our study confirms the asymmetricdistribution of carbon dioxide which has a more uniformdistribution above the comets nucleus than water vapour (Haumlssiget al 2014 Bockeleacutee-Morvan et al 2015 Capaccioni et al 2015)and improves our knowledge about the spatial and temporaldistribution of the gases in the lower coma

2 2 11 2

2

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Author(s) Alessandra Migliorini Giuseppe Piccioni Fabrizio Capaccioni Gianrico Filacchione Dominique Bockeleacutee-Morvan Stefan Erard Cedric Leyrat Michael Combi NicolasFougere Maria Cristina De SanctisInstitution(s) 1 IAPS-INAF 2 LESIA - Observatoire de Paris 3Space Physics Research Laboratory University of Michigan

50305 ndash Rosetta-Alice Observations of the Evolutionof the CO Coma of Comet 67PChuryumov-Gerasimenko During PerihelionAlice is a lightweight low-power far-ultraviolet (700 ndash 2050 Aring)spectrograph onboard Rosetta designed for in situ imagingspectroscopy of the cometary coma during the rendezvous withcomet 67PChuryumov-Gerasimenko We initially reported onspectra obtained following orbit insertion in August 2014 thatshowed multiplets of atomic hydrogen oxygen and carbonconcentrated above the limb of the comet From the relativeintensities of these multiplets we identified photoelectron impactdissociative excitation of H O and CO as the source of theobserved atomic emissions Variations in the relative intensitieswere interpreted in terms of variations in the molecularabundances Emission from CO via resonance fluorescence in theFourth Positive Band system was observed only sporadicallyBeginning in July 2015 as the comet approached perihelion on 13August 2015 the CO emission bands became a strong persistentfeature of the observed spectrum in addition to the atomicmultiplets The CO emissions exhibit a very strong sunwardanti-sunward asymmetry as well as a brightness variation withrotational phase of the comet CO column densities are derivedusing the fluorescence model of Lupu et al (ApJ 670 1473 2007)and compared with the predictions of DSMC models and withconcurrent measurements of H O and CO column densities Thelong term evolution of the CO coma through the cometrsquos perihelionpassage will be presented

Author(s) Paul D Feldman Michael F AHearn Jean-Loup Bertaux Lori M Feaga Joel Wm Parker EricSchindhelm Andrew J Steffl S Alan Stern Harold A WeaverInstitution(s) 1 Johns Hopkins Univ 2 Johns Hopkins UnivApplied Physics Laboratory 3 LATMOS 4 Southwest ResearchInstitute 5 University of Maryland

50306 ndash Comet 67PChuryumov-GerasimenkorsquosIncreasing Atomic Sulfur Abundance Observed byRosetta AliceAlice NASArsquos lightweight and low-power far-ultraviolet (FUV)imaging spectrograph onboard ESArsquos comet orbiting spacecraftRosetta (Stern et al 2007) is continuing its characterization of thenucleus and coma of the Jupiter family comet 67PChuryumov-Gerasimenko (C-G) as it approaches and recedes from perihelionWith a spectral range from 700-2050 Aring Alice has the ability todetect the atomic sulfur multiplets at 1429 Aring 1479 Aring and 1814 AringSulfur in C-Grsquos coma is most likely a dissociation product of CSand OCS but could also be produced after a secondary dissociationfrom H S and SO all molecular species measured in C-Grsquos comaby ROSINA the Rosetta orbiterrsquos mass spectrometerDue to low abundances Alice did not detect sulfur atoms at C-Guntil May 2015 when the comet was at ~17 AU and still 3 monthsfrom perihelion Now sulfur is ubiquitous in Alice observationsabove the limb of the nucleus There is evidence that there is not astrong dependence of the abundance of sulfur on the distance fromthe nucleus in the pre-perihelion radial profiles of the gas whichmay be indicative of the parent molecule and its distribution Thiswill be investigated further The evolution of the presence of thethree sulfur multiplets their relative abundances and excitationprocesses and behavior pre- and post-perihelion will be presented

Author(s) Lori M Feaga Paul D Feldman Michael FAHearn Jean-Loup Bertaux Brian A Keeney Matthew MKnight John Noonan Joel Wm Parker Eric Schindhelm Andrew J Steffl S Alan Stern Ronald J Vervack Harold AWeaverInstitution(s) 1 Johns Hopkins University 2 Johns HopkinsUniversity Applied Physics Lab 3 LATMOS CNRSUVSQIPSL4 Lowell Observatory 5 Southwest Research Institute 6 Univ ofMaryland 7 University of Colorado

50307 ndash Study of the characteristics of the grains inthe coma background and in the jets in comet67PC-G as observed by VIRTIS-M onboard of theRosetta missionWe report observations of the coma of the comet 67PC-Gperformed in the near-IR by VIRTIS-M during the escort phase inApril 2015 We selected observations performed when thespacecraft was at about 150 km from the nucleus in order to coverthe greatest part of the comaWe have chosen observations a) with a diffuse coma without anyevident strong jets and b) with strong jets originating from theldquoneckrdquo region of the nucleusWe analyzed the in changes intensity and spectral behavior of thecoma along the projected nucleocentric distance for both thediffuse coma and for the jetsThe results show that- The emission of the grains in the diffuse coma is going as 1rho inthe FoV of VIRTIS (about 2 km) suggesting the absence of grainfragmentation or sublimation In the region close to the surfacewithin about 400 m there is an increase of the emission which isprobably due to instrumental scattered light from the nucleus thatcan hide the effects due to the grains acceleration- Also for the grains in the jets there is no evidence offragmentation or sublimation in the spectral region where thescattering of the solar radiation is the mechanism of emissionInstead in the thermal region there are strong variations betweenthe regions close to the nucleus and the farther onesThe authors would like to thank ASI (I) CNES (F) DLR (D) NASA(USA) for supporting this research VIRTIS was built by aconsortium formed by Italy France and Germany under thescientific responsibility of the ldquoIstituto di Astrofisica e PlanetologiaSpazialerdquo of INAF (I) which guides also the scientific operationsThe consortium includes also the ldquoLaboratoire deacutetudes spatiales etdinstrumentation en Astrophysiquerdquo of the Observatoire de Paris(F) and the ldquoInstitut fuumlr Planetenforschungrdquo of DLR (D) Theauthors wish to thank the Rosetta Science Ground Segment andthe Rosetta Mission Operations Centre of ESA for their continuoussupport

Author(s) Gian-Paolo Tozzi G Rinaldi U Fink LDoose F Capaccioni G Filacchione D Bockeleacutee-Morvan SErard C Leyrat G Arnold M Blecka M T Capria MCiarniello M Combi S Faggi P Irwin A Migliorini EPaolomba G Piccioni F TosiInstitution(s) 1 Departement of Physics Oxford University 2DLR 3 INAF 4 LESIA-Observatoire de Paris 5 LPL 6 SpaceResearch Centre PAS 7 SPRL The University of Michigan

50308 ndash COSIMA - In-situ dust particlesmeasurements in the inner coma of comet67PChuryumov-GerasimenkoCOSIMA the COmetary Secondary Ion Mass Analyzer is one ofthe three in-situ dust instruments onboard the Rosetta spacecraft[1] Since August 2014 Rosetta has been escorting the comet67PChuryumov-Gerasimenko on its journey toward the innersolar systemCOSIMA is collecting cometary dust particles by exposing metaltargets in the inner coma from 10 to hundreds of kilometers off thecometary nucleus [2] Already several thousands of dust particleshave been collected The targets are imaged with the microscopeCOSISCOPE and some collected particles are then analyzed bySIMS (Secondary Ion Mass Spectrometry) The mass spectracontain positive and negative ions revealing components of thegrains originating from selected surface areas Dust characteristics

1 11 1

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2 2

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4 5 5 55 5 2

2

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4 4 2 6 33 7 3 1 33 3 3

164

will be presented and discussed[1] Kissel et al (2007) Sp Sci Rev 128 82-867 [2] Schulz et al(2015) Nature 518 216-218

Author(s) Anais Bardyn Martin Hilchenbach ChristelleBriois Jochen Kissel Andreas Koch Yves Langevin RitaSchulz Johan Silen Kathrin Altwegg Luigi Colangeli HerveCottin Cecile Engrand Henning Fischer AlbrechtGlasmachers Eberhard Gruumln Gerhard Haerendel HartmutHenkel Herwig Houmlfner Klaus Hornung Elmar KJessberger Harry Lehto Kirsi Lehto Francois Raulin Lena Le Roy Jouni Rynouml Wolfgang Steiger ThomasStephan Laurent Thirkell Roger Thomas Klaus Torkar Kurt Varmuza Karl-Peter Wanczek Nicolas Altobelli DoniaBaklouti Nicolas Fray Pedro Lacerda Nicolas Ligier ZhongYi Lin Philippe Martin Sihane Merouane Franccedilois-Reacutegis Orthous-Daunay John Paquette ClaireRevillet Sandra Siljestroumlm Oliver Stenzel Boris ZaprudinInstitution(s) 1 Center for Space and Habitability (CSH)University of Bern 2 Centre de Sciences Nucleacuteaires et de Sciencesde la Matiegravere - CSNSM CNRSIN2P3-Univ Paris Sud 3Department of Chemistry Materials and Surfaces SP TechnicalResearch Institute of Sweden 4 ESA - ESTEC 5 FinnishMeteorological Institute Climate Research 6 FinnishMeteorological Institute Observation services 7 GraduateInstitute of Astronomy 8 Institut dAstrophysique Spatiale CNRS Universiteacute Paris Sud 9 Institut de Planeacutetologie etdrsquoAstrophysique de Grenoble UMR 5274 Univ Grenoble AlpesCNRS 10 Institut fuumlr Anorganische und Physikalische ChemieUniversitaumlt Bremen 11 Institut fuumlr Planetologie UniversitaumltMuumlnster 12 Institut fuumlr Weltraumforschung OumlsterreichischeAkademie der Wissenschaften 13 Institute of statistics andmathematical methods in economics 14 Laboratoire de Physiqueet Chimie de lEnvironnement et de lEspace CNRS UniversiteacutedrsquoOrleacuteans 15 Laboratory of Molecular Plant Biology Dept ofBiochemistry PharmaCity 16 LISA UMR CNRS 7583 UniversiteacuteParis Est Creacuteteil et Universiteacute Paris Diderot Institut Pierre SimonLaplace 17 Max-Planck-Institut fuumlr extraterrestrische Physik 18Max-Planck-Institut fuumlr Kernphysik 19 Max-Planck-Institut fuumlrSonnensystemforschung 20 Physikalisches Institut UniversitaumltBern 21 RC Seibersdorf Research GmbH Business FieldAerospace Technology 22 Solar System Science OperationDivision ESA-ESAC 23 The University of Chicago Department ofthe Geophysical Sciences 24 Universitaumlt der Bundeswehr LRT-725 Universitaumlt Wuppertal 26 University of Turku Department ofPhysics and Astronomy Tuorla Observatory 27 von Hoerner undSulger GmbH

50309 ndash Three-dimensional kinetic modeling of theneutral and charged dust in the coma of Rosettarsquostarget comet 67PChuryumov-GerasimenkoRosetta is the first mission that escorts a comet along its waythrough the Solar System for an extended amount of time As aresult the target of the mission comet 67PChuryumov-Gerasimenko is an object of great scientific interestDust ejected from the nucleus is entrained into the coma by theescaping gas Interacting with the ambient plasma the dustparticles are charged by the electron and ion collection currentsThe photo and secondary emission currents can also change theparticle charge The resulting Lorentz force together with the gasdrag gravity and radiation pressure define the dust particletrajectoriesAt altitudes comparable to those of the Rosetta trajectory directionof a dust particle velocity can be significantly different from that inthe innermost vicinity of the coma near the nucleus At suchaltitudes the angular distribution of the dust grains velocity has apronounced tail-like structure This is consistent with RosettarsquosGIADA dust observations showing dust grains moving in theanti-sunward directionHere we present results of our model study of the neutral andcharged dust in the coma of comet 67PChuryumov-Gerasimenkocombining the University of Michigan AMPS kinetic particle modeland the BATSRUS MHD model Trajectories of dust particleswithin the observable size range of Rosettarsquos GIADA dust

instrument have been calculated accounting for the radiationpressure gas drag the nucleus gravity the Lorentz force and theeffect of the nucleus rotation The dust grain electric charge iscalculated by balancing the collection currents at the grainrsquoslocation We present angular velocity distribution maps of thesecharged dust grains for a few locations representative of Rosettastrajectory around the cometThis work was supported by US Rosetta project contractsJPL-1266313 and JPL-1266314 and NASA Planetary Atmospheresgrant NNX14AG84G

Author(s) Valeriy Tenishev Dmitry Borovikov Michael RCombi Nicolas Fougere Zhenguang Huang Andre Bieler Kenneth Hansen Gabor Toth Xianzhe Jia Yinsi Shou Tamas Gombosi Martin Rubin Alessandra Rotundi VincenzoDella CorteInstitution(s) 1 INAF Istituto di Astrofisica e PlanetologiaSpaziali 2 Univ of Michigan 3 University of Bern

504 ndash Extrasolar Planets Giant PlanetAtmospheres50401 ndash Saturn as a Transiting ExoplanetPrevious investigations of exoplanet atmospheres have nottargeted those resembling the gas giant planets in our solar systemThese types of exoplanets are too cold to be directly imaged orobserved in emission and their low transit probabilities andfrequencies make characterization via transmission spectroscopy achallenging endeavor However studies of cold giant exoplanetswould be highly valuable to our understanding of planet formationand migration and could place the gas giant members of our ownsolar system in a greater context Here we use solar occultationsobserved by the Visual and Infrared Mapping Spectrometer aboardthe Cassini Spacecraft to extract the 1 to 5 μm transmissionspectrum of Saturn as if it were a transiting exoplanet We detectabsorption features from several molecules despite the presence ofammonia clouds Self-consistent exoplanet atmosphere modelsshow good agreement with Saturns transmission spectrum but failto reproduce the largest feature in the spectrum We also find thatatmospheric refraction determines the minimum altitude thatcould be probed during mid-transit of a Saturn-twin exoplanetaround a Sun-like star These results suggest that transmissionspectroscopy of cold long-period gaseous exoplanets should bepossible with current and future observatories

Author(s) Paul A Dalba Philip S Muirhead Jonathan JFortney Matthew M Hedman Philip D Nicholson Mark JVeyetteInstitution(s) 1 Boston University 2 Cornell University 3University of California Santa Cruz 4 University of IdahoMoscow

50402D ndash Transmission spectral properties of cloudsfor hot Jupiter exoplanetsClouds play an important role in the atmospheres of planetarybodies It is expected that like all the planetary bodies in our solarsystem exoplanet atmospheres will also have substantial cloudcoverage and evidence is mounting for clouds in a number of hotJupiters To better characterise planetary atmospheres we need toconsider the effects these clouds will have on the observedbroadband transmission spectra Here we examine the expectedcloud condensate species for hot Jupiter exoplanets and the effectsof various grain sizes and distributions on the resultingtransmission spectra from the optical to infrared which can beused as a broad framework when interpreting exoplanet spectraWe note that significant infrared absorption features appear in thecomputed transmission spectrum the result of vibrational modesbetween the key species in each condensate which can potentiallybe very constraining While it may be hard to differentiate betweenindividual condensates in the broad transmission spectra it may bepossible to discern different vibrational bonds which candistinguish between cloud formation scenarios such as condensateclouds or photochemically generated species Vibrational mode

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165

features are shown to be prominent when the clouds are composedof small sub-micron sized particles and can be associated with anaccompanying optical scattering slope These infrared featureshave potential implications for future exoplanetary atmospherestudies conducted with JWST where such vibrational modesdistinguishing condensate species can be probed at longerwavelengths

Author(s) Hannah Wakeford David Kent SingInstitution(s) 1 NASA GSFC 2 University of Exeter

50403 ndash Exploring Equilibrium Chemistry for HotExoplanetsIt has been established that equilibrium chemistry is usuallyachieved deep in the atmosphere of hot Jovians where timescalesare short (Line and Young 2013) Thus equilibrium chemistry hasbeen used as a starting point (setting initial conditions) forevaluating disequilibrium processes We explore parameters ofsetting these initial conditions including departures from solarmetallicity the number of species allowed in a system the types ofspecies allowed in a system and different thermodynamic librariesin an attempt to create a standard for evaluating equilibriumchemistry NASAs open source code Chemical Equilibrium andApplications (CEA) is used to calculate model planet abundancesby varying the metallicity in the pressure regime of 01 to 1 barThese results are compared to a variety of exoplanets (Teq between600 and 2100K) qualitatively by color maps of the dayside withdifferent temperature redistributions Additionally CEA (with anupdated thermodynamic library) is validated with thethermochemical model presented in Venot et al (2012) for HD209458b and HD 189733b This same analysis has then beenextended to the cooler planet HD 97658b Spectra are generatedfrom both modelsrsquo abundances using the open source code transit(httpsgithubcomexosportstransit) using the opacities of 15molecules We make the updated CEA thermodyanamic library andsupporting Python scripts to do the CEA analyses available opensource This work was supported by NASA Planetary Atmospheresgrant NNX12AI69G

Author(s) Sarah Blumenthal Joseph Harrington AviMandell Eric Heacutebrard Olivia Venot Patricio Cubillos RyanChallenerInstitution(s) 1 Katholieke Universiteit Leuven 2 NASAGoddard Space Flight Center 3 University of Central Florida

50404D ndash Microphysics of Exoplanet Clouds andHazesClouds and hazes are ubiquitous in the atmospheres of exoplanetsHowever as most of these planets have temperatures between 600and 2000 K their clouds and hazes are likely composed of exoticcondensates such as silicates metals and salts We currently lack asatisfactory understanding of the microphysical processes thatgovern the distribution of these clouds and hazes thus creating agulf between the cloud properties retrieved from observations andthe cloud composition predictions from condensation equilibriummodels In this work we present a 1D microphysical cloud modelthat calculates from first principles the rates of condensationevaporation coagulation and vertical transport of chemicallymixed cloud and haze particles in warm and hot exoplanetatmospheres The model outputs the equilibrium number densityof cloud particles with altitude the particle size distribution andthe chemical makeup of the cloud particles as a function of altitudeand particle mass The model aims to (1) explain the observedvariability in ldquocloudinessrdquo of individual exoplanets (2) assesswhether the proposed cloud materials are capable of forming theobserved particle distributions and (3) examine the role cloudshave in the transport of (cloud-forming) heavy elements inexoplanet atmospheres

Author(s) Peter Gao Bjoumlrn Benneke Heather A Knutson Yuk L YungInstitution(s) 1 Caltech

50405 ndash The Effect of Photochemistry and Quenching

on the Atmospheric Composition of Young DirectlyImaged Giant PlanetsThe last decade has seen significant progress on the directdetection and characterization of young self-luminous giantplanets at wide orbital separation from their host stars Several ofthese planets show evidence for disequilibrium processes liketransport-induced quenching in their atmospheres which affectsthe relative abundances of methane and carbon monoxide and hasother compositional consequences Photochemistry is alsopotentially important on many of these planets despite their largeorbital distance because the young host stars often haveprodigious UV output Disequilibrium chemical processes such asthe above can alter the expected spectroscopic signatures of theplanets and potentially confuse determinations of bulk elementalratios which provide important insights into planet-formationmechanisms We use a thermochemical and photochemicalkinetics and transport model to investigate the effects ofphotochemistry and quenching on young directly imaged planetsResults for specific exoplanets such as the HR 8799 planets and 51Eri b will be presented as will more general trends as a function ofplanet mass orbital distance bulk atmospheric abundances andstellar properties

Author(s) Julianne I Moses Michael R Line ChannonVisscher Mark S Marley Jonathan J Fortney Nikole K Lewis Michael J WolffInstitution(s) 1 Dordt College 2 NASA Ames Research Center3 Space Science Institute 4 Space Telescope Science Institute 5University of California - Santa Cruz

50406 ndash WASP-12b According to the BayesianAtmospheric Radiative Transfer (BART) CodeWe present the Bayesian Atmospheric Radiative Transfer (BART)code for atmospheric property retrievals from transit and eclipsespectra and apply it to WASP-12b a hot (~3000 K) exoplanet witha high eclipse signal-to-noise ratio WASP-12b has beencontroversial We (Madhusudhan et al 2011 Nature) claimed itwas the first planet with a high CO abundance ratio Line et al(2014 ApJ) suggested a high CO abundance to explain the dataStevenson et al (2014 ApJ atmospheric model by Madhusudhan)add additional data and reaffirm the original result stating thatC H and HCN not included in the Line et al models explain thedata We explore several modeling configurations and includeHubble Spitzer and ground-based eclipse dataBART consists of a differential-evolution Markov-Chain MonteCarlo sampler that drives a line-by-line radiative transfer codethrough the phase space of thermal- and abundance-profileparameters BART is written in Python and C Python modulesgenerate atmospheric profiles from sets of MCMC parameters andintegrate the resulting spectra over observational bandpassesallowing high flexibility in modeling the planet without interactingwith the fast C portions that calculate the spectra BARTs sharedmemory and optimized opacity calculation allow it to run on alaptop enabling classroom use Runs can scale constantabundance profiles profiles of thermochemical equilibriumabundances (TEA) calculated by the included TEA code orarbitrary curves Several thermal profile parameterizations areavailable BART is an open-source reproducible-research codeUsers must release any code or data modifications if they publishresults from it and we encourage the community to use it and toparticipate in its development via httpgithubcomExOSPORTSBARTThis work was supported by NASA Planetary Atmospheres grantNNX12AI69G and NASA Astrophysics Data Analysis Program grantNNX13AF38G J Blecic holds a NASA Earth and Space ScienceFellowship

Author(s) Joseph Harrington Patricio E Cubillos Jasmina Blecic Ryan C Challener Patricio M Rojo Nate BLust M Oliver Bowman Sarah D Blumenthal Andrew SDFoster A J FosterInstitution(s) 1 Princeton University 2 UCLA 3 Universidadde Chile 4 University of Central Florida

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166

50407 ndash HST hot Jupiter transmission spectralsurvey The atmospheric circulation of a large hotJupiter sampleEven as we move towards characterizing smaller and coolerexoplanets hot Jupiters continue to be the best transiting planetsfor probing the atmospheric properties of exoplanets and refiningcurrent theory Here we present results from a comprehensiveatmospheric circulation study of nine transiting hot Jupiters thatprobe a wide range of planetary properties including orbitaldistance rotation rate mass radius gravity and stellar insolationWe utilize these circulation models to aid in the interpretation oftransmission spectra obtained using the Space Telescope ImagingSpectrograph (STIS) and Wide Field Camera 3 (WFC3) as a part ofa large Hubble Space Telescope (HST) transmission spectralsurvey These observations have shown a range of spectralbehavior over optical and infrared wavelengths suggesting diversecloud and haze properties in their atmospheres Our ldquogridrdquo ofmodels recovers trends shown in other parametric studies of hotJupiters particularly increased day-night temperature contrastwith increasing equilibrium temperature and equatorialsuperrotation Furthermore we show that three-dimensionalvariations in temperature particularly across the western andeastern terminators and from the equator to the pole can vary byhundreds of Kelvin This can result in vastly different cloudproperties across the limb which can lead to variations intransmission spectra Finally we comment on prospects with theJames Webb Space Telescope (JWST) to further characterize hotJupiters out to longer wavelengths

Author(s) Tiffany Kataria David K Sing Nikole K Lewis Jonathan J Fortney Mark S Marley Adam P ShowmanInstitution(s) 1 NASA Ames Research Center 2 SpaceTelescope Science Institute 3 University of Arizona 4 Universityof California at Santa Cruz 5 University of Exeter

50408 ndash Structure and Evolution of Internally HeatedHot JupitersThe transit radii of many close-in extrasolar giant planets or hotJupiters are systematically larger than those expected frommodels considering only cooling from an initial high-entropy stateThough these planets receive strong irradiation with equilibriumtemperatures of 1000-2500 Kelvin the absorption of stellarincident flux in the upper atmosphere alone cannot explain theseanomalous radii More promising mechanisms involve irradiation-driven meteorological activity which penetrates much deeper intothe planet than direct stellar heating This circulation can lead tolarge-scale mixing and downward transport of kinetic energy bothprocesses whereby a fraction of the stellar incident power istransported downwards to the interior of the planet Here weconsider how deposition of heat at different pressure levels orstructural locations within a planet affects the resulting evolutionTo do so we run global gas giant evolutionary models with with thestellar structure code MESA including additional energydissipation We find that relatively shallow atmospheric heatingalone can explain the transit radii of the hot Jupiter sample butheating in the convective zone is an order of magnitude moreefficient regardless of exact location Additionally a smalldifference in atmospheric heating location can have a significanteffect on radius evolution especially near the radiative-convectiveboundary The most efficient location to heat the planet is at theradiative-convective boundary or deeper We expect that shearinstabilities at this interface may naturally explain energydissipation at the radiative-convective boundary which typicallylies at a pressure of ~1 kilobar after 5 Gyr for a planet with the massand incident stellar flux of HD 209458b Hence atmosphericprocesses are most efficient at explaining the bloated radii of hotJupiters if they can transport incident stellar power downwards tothe top of the inner convective zone

Author(s) Thaddeus D Komacek Andrew N YoudinInstitution(s) 1 University of Arizona

505 ndash Marss Atmosphere50501 ndash How relevant is heterogeneous chemistry onMars Strong tests via global mapping of water andozone (sampled via O dayglow)Ozone and water are powerful tracers of photochemical processeson Mars Considering that water is a condensable with amultifaceted hydrological cycle and ozone is continuously beingproduced destroyed on short-time scales their maps can test thevalidity of current 3D photochemical and dynamical modelsComparisons of modern GCM models (eg Lefegravevre et al 2004)with certain datasets (eg Clancy et al 2012 Bertaux et al 2012)point to significant disagreement which in some cases have beenrelated to heterogeneous (gas-dust) chemistry beyond the classicalgas-gas homogeneous reactionsWe address these concerns by acquiring full 2D maps of water andozone (via O dayglow) on Mars employing high spectral infraredspectrometers at ground-based telescopes (CRIRESVLT andCSHELLNASA-IRTF) By performing a rotational analysis on theO lines we derive molecular temperature maps that we use toderive the vertical level of the emission (eg Novak et al 2002)Our maps sample the full observable disk of Mars onMarch252008 (Ls=50deg northern winter) and on Jan292014(Ls=83deg northern spring) The maps reveal a strong dependenceof the O emission and water burden on local orography while thetemperature maps are in strong disagreement with current modelsCould this be the signature of heterogeneous chemistry We willpresent the global maps and will discuss possible scenarios toexplain the observationsThis work was partially funded by grants from NASAs PlanetaryAstronomy Program (344-32-51-96) NASArsquos Mars FundamentalResearch Program (20395902022029) NASArsquos AstrobiologyProgram (344-53-51) and the NSF-RUI Program (AST-805540)We thank the administration and staff of the European SouthernObservatoryVLT and NASA-IRTF for awarding observing time andcoordinating our observationsBertaux J-L Gondet B Lefegravevre F et al 2012 J Geophys ResPl 117 pp 1ndash9Clancy RT Sandor BJ Wolff MJ et al 2012 J Geophys ResPl 117 p E00J10Lefegravevre F Lebonnois S Montmessin F amp Forget F 2004 JGeophys Res Pl 109 pp 1ndash20Novak RE Mumma MJ Disanti MA et al 2002 Icarus 158(1) pp 14ndash23

Author(s) Geronimo Luis Villanueva Michael J Mumma Robert E NovakInstitution(s) 1 Iona College 2 NASA-Goddard Space FlightCenter

50502 ndash Investigating SEP and Auroral Consequencesof the Magnetic Topology Near MarsThe diffuse UV aurora at Mars discovered by MAVENs IUVS hasbeen shown to be caused by solar energetic electrons observed byMAVENs SEP detector but the spatial patterns of these emissionsare still under study In the meantime BATS-R-US models of theMars-solar wind interaction have been shown to describe thein-situ plasma and field observations well to first order We use aset of nominal simulations together with a few case study results toexamine the geometry of the magnetic field line footpoints that areopen-or connected to the interplanetary field- in these models Inaddition the subset of these that are directly connected to the Sunvia the upstream magnetic field are identified We use these resultsfor comparisons with the reported diffuse auroral occurrence mapand to describe what can happen during the passage of an ICMEWe also consider the potential use of these field line tracings forunderstanding the geometry of the SEP ion shadowing at theMAVEN orbital period

5 5 24 1 3

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167

Author(s) Janet Luhmann Christina O Lee Rob Lillis Davin Larson David L Mitchell Shannon M Curry TakuyaHara Jack Connerney Jared Espley Nick Schneider Chuanfei Dong Yingjuan Ma Bruce M JakoskyInstitution(s) 1 AOSS University of Michigan 2 IGPP UCLA 3LASP University of Colorado 4 NASA GFSC 5 SSL University ofCalifornia Berkeley

50503 ndash Impacts of an Interplanetary Coronal MassEjection and the Crustal Magnetic Fields to theMartian hot O coronaAn interplanetary coronal mass ejection (ICME) is a large amountof mass entrained in the heliospheric magnetic field andpropagating outward from the Sun into the interplanetary mediumUpon arrival at Mars ICMEs interact with its upper atmosphereand ionosphere causing important impacts in the planetaryenvironment In March 2015 a strong solar event was observedand associated with a major ICME The major ICME eventsaroused a chain of events on Mars which were detected by theinstruments onboard Mars Atmosphere and Volatile EvolutioN(MAVEN) The consequences in the upper atmosphere are directlyrelated to the important processes that lead to the atmosphericescape We report here our examinations of the impacts of theMarch 8 ICME event on the Martian hot O corona by using our3D framework which couples the Mars application of the AdaptiveMesh Particle Simulator (M-AMPS) the Mars Global Ionosphere-Thermosphere Model (M-GITM) and the Mars multi-fluid MHD(MF-MHD) model Also we present the effects of the crustalmagnetic fields on the structure of the hot O corona to study theinteresting signatures of the crustal magnetic fields Due to theminimal impacts of the ICME deep in the thermosphere andionosphere where the maximum production of hot O occurs ourmodel results showed a stable hot O corona during and after thepeak ICME event However the structure of the corona wasaffected by the existence of the crustal magnetic fields with adecrease in escape rate

Author(s) Yuni Lee Michael Combi Valeriy Tenishev Stephen BougherInstitution(s) 1 University of Michigen

50504 ndash A Comet Engulfs Mars MAVEN observationsof Comet Siding Springrsquos Effects on the MartianMagnetosphereThe nucleus of Comet C2013 A1 (Siding Spring) passed within135000 km of Mars on Oct 19 2014 Thus the cometary coma andthe plasma it produces washed over Mars for several hoursproducing significant effects in the martian magnetosphere andupper atmosphere We present observations from MAVENrsquosparticles and fields instruments that show the martianmagnetosphere was severely distorted during the cometrsquos passageWe note four specific major effects 1) a variable inducedmagnetospheric boundary 2) a strong rotation of the magneticfield as the comet approached 3) severely distorted and disorderedionospheric fields during the cometrsquos closest approach and 4)unusually strong magnetosheath turbulence lasting hours after thecomet left We argue that the comet had effects comparable to alarge solar storm (in terms of incident energy) and so was afascinating opportunity to explore atmospheric escape MAVENrsquosprimary science objective

Author(s) Jared R Espley Gina A DiBraccio JackConnerney David Brain Jacob Gruesbeck Yasir Soobiah Jasper Halekas Michael Combi Janet Luhmann YingjuanMa Yingdong Jia Bruce JakoskyInstitution(s) 1 Atmospheric Oceanic and Space SciencesDepartment University of Michigan 2 Department of EarthPlanetary and Space Sciences UCLA 3 Department of Physics andAstronomy University of Iowa 4 Laboratory for Atmosphericand Space Physics University of Colorado 5 NASA GoddardSpace Flight Center 6 Space Sciences Laboratory University ofCalifornia

50505 ndash Mars Exospheric Temperature Trends as

Revealed by MAVEN NGIMS MeasurementsThe Martian dayside upper thermosphere and exospheretemperatures (Texo) have been the subject of considerable debateand study since the first Mariner ultraviolet spectrometer (UVS)measurements (1969ndash1972) up to recent Mars Express SPICAMUVS measurements (2004ndashpresent) (eg see reviews by Stewart1987 Bougher et al 2000 2014 Muumleller-Wodarg et al 2008Stiepen et al 2014) Prior to MAVEN the Martian upperatmosphere thermal structure was poorly constrained by a limitednumber of both in-situ and remote sensing measurements atselected locations seasons and periods scattered throughout thesolar cycle Nevertheless it is recognized that the Mars orbiteccentricity determines that both the solar cycle and seasonalvariations in upper atmosphere temperatures must be consideredtogether The MAVEN NGIMS instrument measures the neutralcomposition of the major gas species (eg He N O CO N O NO Ar and CO ) and their major isotopes with a verticalresolution of ~5 km for targeted species and a target accuracy oflt25 for most of these species (Mahaffy et al 2014 2015)Corresponding temperatures can now be derived from the neutralscale heights (especially CO Ar and N ) (eg Mahaffy et al 2015Bougher et al 2015) Texo mean temperatures spanning ~200 to300 km are examined for both Deep Dip and Science orbits over11-February 2015 (Ls ~ 290) to 14-July 2015 (Ls ~ 12) Duringthese times dayside sampling below 300 km occurred from thedusk terminator across the dayside and approaching the dawnterminator NGIMS temperatures are investigated to extract spatial(eg SZA) and temporal (eg orbit-to-orbit seasonal solarrotational) variability and trends over this sampling period Solarand seasonal driven trends in Texo are clearly visible but orbit-to-orbit variability is significant and demands further investigationto uncover the major drivers that are responsible

Author(s) Stephen W Bougher Kirk Olsen Kali Roeten Jared Bell Paul Mahaffy Mehdi Benna Meredith Elrod BruceJakoskyInstitution(s) 1 Goddard Space Flight Center 2 NationalInstitute for Aerospace 3 Univ Colorado 4 Univ of Michigan

50506 ndash MAVEN data-model comparison of theresponse of heavy pick-up ions during extremeconditions at MarsMAVEN has observed multiple interplanetary coronal massejection (ICME) events at Mars showing dramatic enhancementsof heavy ion precipitation into the upper atmosphere Heavy ionprecipitation is the primary driver of sputtering which is believedto be one of the main channels for atmospheric erosion duringearlier epochs of our solar system when the solar activity and EUVintensities were much higher than the present day Using MAVENobservations of extreme solar wind events we simulateatmospheric precipitation using fluid and kinetic models andcompare with MAVEN observations The fluid model reproducesthe observed features in the solar wind density velocity andmagnetic field seen along the MAVEN orbit during the March 8thICME event and the subsequent precipitation shows strongagreement with other published predictions of sputtering inextreme conditions

Author(s) Shannon Curry Janet G Luhmann Chuanfei DDong David Brain Francois Leblanc Ronan Modolo JasperHalekas James McFadden Jack Connerney Jared Espley David Mitchell Davin Larson Takuya Hara Bruce JakoskyInstitution(s) 1 LATMOS UVSQ 2 NASA Goddard SpaceFlight Center 3 UC Berkeley Space Sciences Laboratory 4University of Colorado LASP 5 University of Iowa 6 Universityof Michigan

50507 ndash Initial Results from the MAVEN IUVS EchelleChannelThe study of the evolution of water on Mars includesunderstanding the high D H ratio in the atmosphere and surfacewater today believed to be linked to the historic loss of a largevolume of primordial water (the lighter H escapes faster than theheavier D) Toward this end the IUVS instrument on MAVEN

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contains the first echelle spectrograph to be sent to another planetThe system has a novel optical design to enable long-aperturemeasurements of emission lines in the absence of continuumintended primarily to measure the H and D Ly α emission lines andthereby the DH ratio from the martian upper atmosphere Thesystem also detects the OI 1304 triplet with the three componentlines well resolved The specific scientific goal of the echellechannel is to measure the H and D Ly α emissions and to discoverhow the H and D densities temperatures and escape fluxes varywith location season topography etc Recent IR observationsindicate large variations in the DH ratio in the lower atmospherefrom location to location and possibly seasonal changes[Villanueva et al 2015] HST and MEX measurements of the Hcorona of Mars show large (order of magnitude) changes in the Hexosphere and escape flux with changing seasons andorheliospheric distance [Clarke et al 2014 Chaffin et al 2014] Earlyresults from the echelle channel regarding how these parametersapply to martian deuterium will be presented

Author(s) John T Clarke Majd Mayassi WilliamMcClintock Nick Schneider Justin Deighan Ian Stewart Greg Holsclaw Bruce JakoskyInstitution(s) 1 Boston Univ 2 Univ of Colorado

50508 ndash Mars atmospheric escape constrained usingMAVEN IUVS coronal observationsEvery planetary atmosphere is capped by a corona an extendedextremely tenuous region where collisions are negligible andparticles follow ballistic trajectories At Mars the corona isespecially extended due to the low gravity of the planet and a largenumber of coronal particles are on escaping trajectories Suchescape has played a critical role in the history of the Mars systemlikely removing a substantial fraction of the water initially presenton the planet but the mechanism and magnitude of this escaperemains poorly constrained Currently in orbit at Mars MAVENsImaging Ultraviolet Spectrograph (IUVS) is mapping thedistribution of oxygen and hydrogen above 200 km at a high spatialand temporal cadence revealing a dynamic corona inunprecedented detail Results will be presented demonstrating thatthe H in the corona is not spherically symmetric in its distributionand can potentially be used as a tracer of thermospheric generalcirculation and that non-thermal hot O (in contrast with morespatially confined cold thermal O) is ionospherically sourced witha characteristic energy of 11 eV and responds to solar EUV forcingThese results will be interpreted in terms of their impact on ourcurrent understanding of how atmospheric escape operates todayWe will also discuss how these processes may have acted in thepast to deplete Mars initial water inventory potentially altering theredox balance of the planet and atmosphere through differentialescape of H and O

Author(s) Michael S Chaffin Justin Deighan Jean-YvesChaufray Sonal Jain Ian Stewart Bill McClintock MatteoCrismani Arnaud Stiepen Greg Holsclaw John Clarke Franck Montmessin Frank Eparvier Ed Thiemann PhilChamberlain Nick Schneider Bruce JakoskyInstitution(s) 1 Boston University 2 Laboratoire de PhysiqueAtmospheacuterique et Planeacutetaire (LPAP) 3 LATMOSIPSL 4 NASAGoddard 5 University of Colorado

50509 ndash Structure and variability of the Martianupper atmosphere Ultraviolet dayglow observationsby MAVENIUVSMars has been studied extensively at ultraviolet wavelengthsstarting from Mariner 6 and 7 Mariner 9 and more recently bySPICAM aboard Mars Express The results from thesemeasurements reveal a large variability in the composition andstructure of the Martian upper atmosphere However due to thelack of simultaneous measurements of energy input (such as solarelectromagnetic and particle flux) and limitations in theobservation geometry and data itself this variability is still not fullyunderstoodWe report a comprehensive study of Mars dayglow observations bythe Imaging Ultraviolet Spectrograph (IUVS) aboard the Mars

Atmosphere and Volatile EvolutioN (MAVEN) satellite focusingon vertical and global upper atmospheric structure and seasonalvariability The dayglow emission spectra show features similar toprevious UV measurements at Mars IUVS has detected a secondlow-altitude peak in the emission profile of OI 2972 nmconfirming the prediction that the absorption of solar Lyman alphaemission is an important energy source there We find a significantdrop in thermospheric scale height and temperature between Ls =218deg and Ls = 337 - 352deg attributed primarily to the decrease insolar activity and increase in heliocentric distance The CO UVDpeak intensity is well correlated with simultaneous observations ofsolar 17 - 22 nm irradiance at Mars by Extreme Ultraviolet Monitor(EUVM) aboard MAVEN Variations of the derived CO densityalso exhibit significant persistent global structure with longitudinalwavenumbers 1 2 and 3 in a fixed local solar time frame pointingto non-migrating atmospheric tides driven by diurnal solar heatingWe will present and discuss the variability in Martian UV dayglowits dependence on solar EUV flux and the importance of IUVSobservations in our current understanding of Marsrsquo thermosphere

Author(s) Justin Deighan Sonal K Jain Daniel Y Lo AIan F Stewart Nicholas M Schneider Arnaud Stiepen J ScottEvans Michael H Stevens Roger V Yelle Scott L England Michael Scott Chaffin Matteo Crismani William EMcClintock John T Clarke Greg M Holsclaw FranckLefevre Franck Montmessin Edward MB Thiemann FrankEparvier Bruce M JakoskyInstitution(s) 1 Center for Space Physics Boston University 2Computational Physics Inc 3 Laboratory for Atmospheric andSpace Physics University of Colorado 4 LATMOSCNRS 5Lunar and Planetary Laboratory University of Arizona 6 NavalResearch Laboratory 7 Space Sciences Laboratory University ofCalifornia

506 ndash Comets Physical CharacteristicsDynamics and Composition50601D ndash Comets as natural laboratoriesInterpretations of the structure of the innerheliosphereMuch has been learnt about the heliospherersquos structure from insitu solar wind spacecraft observations Their coverage is howeverlimited in time and space Comets can be considered to be naturallaboratories of the inner heliosphere as their ion tails trace thesolar wind flow Solar wind conditions influence cometsrsquo inducedmagnetotails formed through the draping of the heliosphericmagnetic field by the velocity shear in the mass-loaded solar windI present a novel imaging technique and software to exploit the vastcatalogues of amateur and professional images of comet ion tailsMy projection technique uses the cometrsquos orbital plane to sampleits ion tail as a proxy for determining multi-latitudinal radial solarwind velocities in each cometrsquos vicinity Making full use of manyobserving stations from astrophotography hobbyists toprofessional observatories and spacecraft this approach is appliedto several comets observed in recent years This work thus assessesthe validity of analysing cometsrsquo ion tails as complementary sourcesof information on dynamical heliospheric phenomena and theunderlying continuous solar windComplementary velocities measured from folding ion rays and avelocity profile map built from consecutive images are derived asan alternative means of quantifying the solar wind-cometaryionosphere interaction including turbulent transient phenomenasuch as coronal mass ejections I review the validity of thesetechniques by comparing near-Earth comets to solar wind MHDmodels (ENLIL) in the inner heliosphere and extrapolatedmeasurements by ACE to the orbit of comet C2004 Q2(Machholz) a near-Earth comet My radial velocities are mappedback to the solar wind source surface to identify sources of thequiescent solar wind and heliospheric current sheet crossingsComets were found to be good indicators of solar wind structurebut the quality of results is strongly dependent on the observinggeometry

1 12 2 2 2

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Author(s) Yudish Ramanjooloo Geraint H Jones AndrewJ Coates Mathew J OwensInstitution(s) 1 University College London (MSSL) 2University of Hawaii 3 University of Reading (Dept ofMeteorology)

50602D ndash Five years of comet narrow bandphotometry and imaging with TRAPPISTTRAPPIST is a 60-cm robotic telescope in La Silla Observatory [1]mainly dedicated to the study of exoplanets and comets Thetelescope is equipped with a set of narrow band cometary filtersdesigned by the NASA for the Hale-Bopp observing campaign [2]Since its installation in 2010 we gathered a high quality andhomogeneous data set of more than 30 bright comets observedwith narrow band filters Some comets were only observed for a fewdays but others have been observed weekly during several monthson both sides of perihelion From the images we derived OH NHCN C and C production rates using a Haser [3] model inaddition to the Afρ parameter as a proxy for the dust productionWe computed production rates ratios and the dust color for eachcomet to study their composition and followed the evolution ofthese ratios and colors with the heliocentric distanceThe TRAPPIST data set rich of more than 10000 images obtainedand reduced in an homogeneous way allows us to address severalfundamental questions such as the pristine or evolutionary originof composition differences among comets The evolution of cometactivity with the heliocentric distance the differences betweenspecies and from comet to comet will be discussed Finally thefirst results about the one year campaign on comet C2013 US10(Catalina) and our recent work on the re-determination of Haserscalelengths will be presented[1] Jehin et al The Messenger 145 2-6 2011[2] Farnham et al Icarus 147 180-204 2000[3] Haser Bulletin de lrsquoAcadeacutemie Royal des Sciences deBelgique63 739 1957

Author(s) Cyrielle Opitom Emmanuel Jehin JeanManfroid Damien Hutsemeacutekers Michaeumll Gillon PierreMagainInstitution(s) 1 University of Liegravege

50603 ndash Daughter Species Abundances in CometC2014 Q2 (Lovejoy)We present analysis of high spectral resolution optical spectra ofC2014 Q2 (Lovejoy) acquired with the Tull Coude spectrometer onthe 27-meter Harlan J Smith Telescope at McDonald Observatoryand the ARCES spectrometer mounted on the 35-meterAstrophysical Research Consortium Telescope at Apache PointObservatory Both Tull Coude and ARCES provide high spectralresolution (R=30000-60000) and a large spectral range ofapproximately 3500-10000 Angstroms We obtained twoobservation epochs one in February 2015 at a heliocentric distanceof 13 AU and another in May 2015 at a heliocentric distance of 19AU Another epoch in late August 2015 at a heliocentric distance of30 AU is scheduled We will present production rates of thedaughter species CN C CH C and NH We will also presentH O production rates derived from the [OI]6300 emission as wellas measurements of the flux ratio of the [OI]5577 Angstrom line tothe sum of the [OI]6300 and [OI]6364 Angstrom lines (sometimesreferred to as the oxygen line ratio) This ratio is indicative of theCO abundance of the comet As we have observations at severalheliocentric distances we will examine how production rates andmixing ratios of the various species change with heliocentricdistance We will compare our oxygen line measurements toobservations of CO made with Spitzer as well as our otherdaughter species observations to those of candidate parentmolecules made at IR wavelengths

Author(s) Adam McKay Anita Cochran Neil Dello Russo Michael KelleyInstitution(s) 1 Johns Hopkins Applied Physics Laboratory 2University of Maryland 3 University of Texas Austin

50604 ndash A Comprehensive Near-Infrared Spectral

Survey of comet C2014 Q2 (Lovejoy) 09-25 μmIn February 2015 we acquired a comprehensive high resolutionspectral survey of comet C2014 Q2 (Lovejoy) in the 09-25 μmrange with GIANO - the near-IR spectrograph on TNG (the ItalianTelescopio Nazionale Galileo in Canary Island ES) We detectedemission from multiple ro-vibrational bands of H O the redsystem of CN and many other features whose precursors are nowbeing identified We also searched for overtone lines of othervolatiles (eg CH CO and C ) along with OH prompt andfluorescent emissions and atomic carbon prompt emission at98239850 Å These species are relevant to astrobiology owing toquestions regarding the origin of water and organics on terrestrialplanetsComets are the most pristine bodies in the solar system and wateris the most abundant constituent of cometary ice ndash its productionrate is used to quantify cometary activity Along with the waterproduction rate the newly discovered water bands offer theopportunity to measure the ortho-para ratio and nuclear spintemperature with high accuracy in a single instrument settingthereby eliminating many sources of systematic error andpermitting comparisons amongst comets This can clarify thenature and meaning of the spin temperature in the cosmic contextHigh-resolution spectroscopy in the infrared (27 - 5 μm) is awell-established powerful tool for quantifying abundances of tracecompounds and water in cometary comae Implementing thisapproach in the near-IR region (09-25 μm) will extend thiscapability to new band systems and will also reduce thermal noisesignificantlyThese observations open new pathways for cometary science in thenear-infrared spectral range (09-25 μm) and establish thefeasibility of astrobiology-related scientific investigations withfuture high resolution IR spectrographs on 30-m class telescopeseg the HIRES spectrograph on the E-ELT telescope This work ispart of Sara Faggirsquos PhD thesis project

Author(s) Sara Faggi Geronimo Luis Villanueva Michael JMumma John Robert Brucato Gian-Paolo Tozzi ErnestoOlivaInstitution(s) 1 INAF Osservatorio Astrofisico di Arcetri 2NASA Goddard Space Flight Center

50605 ndash The distribution and excitation of CH OH incomet C2012 K1 (PanSTARRS) from ALMAWe present measurements of spatially and spectrally resolvedCH OH emission from the coma of comet C2012 K1(PanSTARRS) observed using the Atacama LargeMillimetersubmillimeter Array (ALMA) in June 2014 TheCH3OH emission is centrally peaked with a spatial profileconsistent with production from the sublimation of ices from thenucleus From the detection of multiple lines of CH OH in theJ=7-6 and K=3-2 bands around 339 and 252 GHz respectively theline-of-sight average rotational excitation temperatures (T ) havebeen derived as a function of spatial position across the coma Atthe CH OH peak we find Trot=92 K falling to about 40 K at adistance of 1000 km The temperature does not fall monotonicallybut shows a double-peaked structure indicative of a heating sourceat distances gt=500 km from the nucleus

Author(s) Stefanie N Milam Martin A Cordiner JeremieBoissier Steven B Charnley Anthony Remijan MichaelMumma Geronimo Villanueva Lucas Paganini DominiqueBockelee-Morvan Jacques Crovisier Nicolas Biver BonchoBonev Yi-Jehng Kuan Dariuz LisInstitution(s) 1 Institut de Radioastronomie Millimetrique 2NASA Goddard Space Flight Center 3 National Radio AstronomyObservatory 4 National Taiwan Normal University 5Observatoire de Paris

50606 ndash Spatial-Spectral Studies of CometaryVolatiles and the Physical Environment of InnerCometary AtmospheresHow is water released in comets - directly from the nucleus versussublimation from icy grains in the coma How common and howprevalent are icy grains as a source of gas-phase water (and other

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volatiles) among the active comet population These questions arebeing addressed through synergy between spatial-spectral studiesof native volatiles in comets and the physical models tested againstthem This synergy is extending the state-of-the-art in bothdomains Ground-based near-IR spectroscopy (Keck NASA IRTFand ESO VLT) allowed measurements of spatially resolved innercoma temperatures and column densities for H2O ndash the mostabundant volatile in the coma These measurements motivated theinclusion of new physics in the models The evolved models nowopen new questions and trigger improvement in the accuracy ofmeasured temperature profiles most recently extended to othermolecules (HCN in the near-IR) and to other wavelength domains(CH3OH through ALMA S Milam et al this meeting) The netresult is deeper quantitative insight into the competition amongprocesses that cause heating and cooling of the coma and into theprevalent mechanism(s) for release of native volatiles in the gasphaseThe same inner-coma modeling formalisms are used to interpretboth the environment of Rosettas mission target(67PChuryumovndashGerasimenko) and those from theground-based observations reported here (Combi et al 2015LPSC 1714 Fougere et al this meeting) While ground-basedspectroscopy offers less detail than in-situ missions it can probethe comae of many comets that may differ greatly from one anotherand from Rosettas target thereby assessing the extent to which theinner-coma environment of 67P is unique and how it relates toother cometsWe gratefully acknowledge support from NASA PlanetaryAtmospheres Solar System Workings Planetary Astronomy andAstrobiology programs and from NSF Astronomy and AstrophysicsResearch Grants program

Author(s) Boncho P Bonev Nicolas Fougere Geronimo LVillanueva Michael J Mumma Michael R Combi Michael ADiSanti Lucas Paganini Martin Cordiner Erika L Gibb Stefanie N MilamInstitution(s) 1 Catholic University of America 2 NASAGoddard Center for Astrobiology 3 University of Michigan 4University of Missouri - St Louis

50607 ndash Lightcurves and revised masses of the largeparticles at comet 103PHartley 2Comet 103PHartley 2 is a hyperactive comet Such comets havenuclei with surface areas comparable to the surface area required tosustain their water production rates implying the surface is near100 active However images of the nucleus and inner coma bythe Deep Impact Flyby spacecraft show signficant localized activitydominated by a single strong active area (AHearn et al 2011Science 332 1396) This active area seems to be driven by carbondioxide ice sublimation which releases water ice into the coma(Protopapa et al 2014 Icarus 238 191) It has been hypothesizedthat this water-ice-rich material is the origin of the cometshyperactivity but this has not yet been definitively demonstratedThe Deep Imact spacecraft also imaged thousands of point sourcessurrounding the nucleus of the comet (AHearn et al 2011) Thesesources are particles ejected by the comet the largest of which isestimated to have a radius between 30 and 400 cm The wide rangein the radius estimate is due to the unknown photometricproperties of the particles If the particles are icy they maycontribute a significant fraction of the comets water productionrate (Kelley et al 2013 Icarus 222 634)To better elucidate the physical properties of the particles wegenerated particle lightcurves based on the identifications ofHermalyn et al (2013 Icarus 222 625) and a an independent(manual) particle search We find no clear correlation with time orphase angle suggesting the lightcurves are primarily driven byparticle shape rather than sublimation fragmentation or phaseeffects Three lightcurves are double-peaked indicating rotationperiods near 75 to 300 s At least one other lightcurve suggests arotation period of order 20 sWe also present corrections to the analysis of Kelley et al (2013)that decrease the total large particle population mass estimates bytwo orders of magnitude Despite the revision the large particlesmay still account for the comets hyperactivity if they are more likethe low-albedo ice-rich nucleus rather than high-albedo icy grains

However an understanding of the large particle production rate isneeded before definitive statements may be made

Author(s) Michael S Kelley Tony L Farnham BrendanHermalyn Dennis Bodewits Michael F AHearnInstitution(s) 1 NASA Ames Research Center 2 Univ ofMaryland

50608 ndash Volatile Abundance and Distribution in theTempel 1 Ejecta CloudOn 4 Jul 2005 the Deep Impact Impactor Spacecraft collided withcomet Tempel 1 creating an ejecta cloud that was observed by theDeep Impact Flyby Spacecraft (DIF) as well as Earth and spacebased observatories The High Resolution Instrument InfraredSpectrometer (HRI-IR) onboard DIF acquired several spectralscans of this ejecta cloud in the minutes immediately after impactHRI-IR has a spectral range of 105 to 485 microns This spectralrange allows for water vapor water ice organics CO and CO to bedetected simultaneously if each species is sufficiently abundantWe present an analysis of the quantity and spatial distribution ofwater organics and CO in the Tempel 1 ejecta cloud Variation inabundance either absolute or relative will be compared tomorphological features in the ejecta cloud present in visible imagesacquired by the Medium and High Resolution Imagers onboardDIF The composition of the ejecta cloud will also be compared withthat of the 2 Jul 2005 natural outburst and quiescent activity levelsat Tempel 1

Author(s) Mark J Moretto Lori M Feaga Michael FAHearn Silvia Protopapa Jessica M Sunshine Tony LFarnhamInstitution(s) 1 University of Maryland

50609 ndash A Preliminary Analysis of Cometary Dust inthe 1 Year of the NEOWISE Restarted MissionAs some of the most pristine objects in the Solar System cometspresent an opportunity to understand the mechanics and chemistryof the planetary formation era By studying a large number ofcomets in different dynamical classes we can better understand theensemble properties of the different classes and begin tocharacterize the evolution that may have occurred since theirformationIn late 2013 the WISE spacecraft was brought out of hibernationand renamed NEOWISE with a renewed goal to detect andcharacterize small bodies using its 34 and 46-micron bandsSurvey operations began in December 2013 [1] and the first year ofdata was publicly released in March 2015 [2] During the course ofthe first year of the restarted mission over 60 comets wereserendipitously detected by NEOWISE at heliocentric distancesbetween ~1-75 AU including 3 newly discovered comets Thecomets detected were split roughly evenly between short-periodand long-period comets and many displayed extended duststructures Several of the comets were detected multiple times overthe course of the year and some were also seen during the primeWISE mission This long baseline allows for an intriguing analysisof long-term cometary behaviorNEOWISE has sampled the behavior of these comet dynamicalsub-types over the thermal infrared and near-infraredreflected-light regimes where effects from different particle sizeranges of dust may dominate the morphologies and observedfluxes We present a preliminary analysis of the cometary dust seenin these data including dynamical models to constrain the sizesand ages of the dust particles We discuss how these resultscompare to those obtained for the comets seen in the 12 and22-micron WISE prime mission dataAcknowledgments This publication makes use of data productsfrom (1) WISE which is a joint project of UCLA and JPLCaltechfunded by NASA and (2) NEOWISE which is a project ofJPLCaltech funded by the Planetary Science Division of NASAEK RS and SS gratefully acknowledge support from the NASAPostdoctoral Program References [1] Mainzer A et al 2014ApJ 7921 [2] Cutri R et al 2015 httpwise2ipaccaltechedudocsreleaseneowiseexpsup

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Author(s) Emily A Kramer James M Bauer Yanga RFernaacutendez Amy K Mainzer Tommy Grav Joseph R Masiero Carolyn R Nugent Sarah Sonnett Roc Cutri RachelStevensonInstitution(s) 1 Infrared Processing and Analysis Center 2 JetPropulsion Laboratory 3 Planetary Science Institute 4University of Central Florida

50610 ndash Is comet 19PBorrelly changing its spin stateWe observed comet 19PBorrelly from September 6-12 and October9-14 2014 at the SOAR telescope in Chile The comet was atheliocentric and geocentric distances of 29 AU and 22 AU inSeptember and of 27 AU and 24 AU in October We carried outlightcurve observations to derive an accurate rotation period to becompared with that derived by Mueller et al (2010 Icarus 209745) from observations of the 20002001 apparitionThe ultimate goal for these and lightcurve observations of othercomets is to derive changes in the rotation period to test whetherthe changes are really independent of the active fraction as seen forfour other comets (Samarasinha and Mueller 2013 ApJL 775article id L10) Establishing such a correlation will enable theprediction of rotational changes for other comets as well It will alsohave far reaching implications for nuclear activity and itscharacteristics as well as for understanding the reaction torquesdue to outgassingWe gratefully acknowledge support for this work from NASA PASTgrant NNX14AG73G

Author(s) Beatrice E A Mueller Nalin H SamarasinhaInstitution(s) 1 Planetary Science Institute

50611 ndash 322PSOHO 1 Sunskirting Comet orAsteroidComet 322PSOHO 1 (P1999 R1) is a unique object a short periodcomet (P = 399 yr) on a ldquosunskirting orbitrdquo (q = 0053 AU or ~11solar radii) with no dynamical linkage to any other known comets322P was discovered in SOHO images in 1999 and has been seenby SOHO on every subsequent orbit 2003 2007 and 2011 (it isexpected to be observed by SOHO again during its next perihelionpassage in 2015 September) During this time it has not displayedan obvious coma or tail in SOHO images but has exhibited anon-asteroidal lightcurve that strongly suggests the presence of anunresolved coma Equilibrium temperatures during theseobservations exceed 1000 K so it is unclear if 322P is active due tosublimation of volatile ices like a typical comet or if it is anotherwise inactive object that is losing material through moreexotic processes such as sublimation of refractory materials orthermal fracturing Due to the very large uncertainty in orbitsderived from SOHO observations and 322Prsquos assumed small size2015 was the first reasonable opportunity to recover it at largeheliocentric distance and attempt to determine its heritagetraditional comet or asteroid We recovered 322P on 2015 May 22with the VLT and observed it again on five epochs in June and Julywith Spitzer the VLT and the Discovery Channel Telescope Theseare the first successful observations of any SOHO-discovered shortperiod comet at traditional cometary distances 322P appearedpointlike in all images (heliocentric distances from 21 to 12 AU)implying an inactive object having a diameter of a few hundredmeters We will report on these observations focusing onconstraining properties of 322P such as activity level color andalbedo that may help us deduce whether or not it is of a cometaryor asteroidal origin

Author(s) Matthew M Knight Alan Fitzsimmons MichaelS P Kelley Colin SnodgrassInstitution(s) 1 Lowell Observatory 2 Queens UniversityBelfast 3 The Open University 4 University of Maryland

507 ndash Origins of Planetary Systems50701D ndash Collisional properties and dynamicalaccretion of centimeter-sized protoplanetesimalsThe seeds of planetesimals that formed in the turbulent gaseous

environment of the nascent protoplanetary disk have manybarriers to overcome in their growth from millimeter to meter-sizedand larger objects such as collisional disruption and orbital decayCentimeter-sized agglomerates can be weakly bound and quitefragile and at these sizes self-gravity is almost non-existentElectrostatic surface forces such as van der Waalrsquos forces play acritical role in holding loosely bound rubble-piles together Wewish to further understand the mechanical material collisionalproperties and outcomes of collisions between cm-sizedrubble-piles at low speeds that may lead to accretion Thecollisional outcomes can be determined by a set of definablecollision parameters and experimental constraints on theseparameters will improve formation models for planetesimals Wehave carried out a series of laboratory microgravity collisionexperiments of small aggregates to determine under whatconditions collisional growth can occur using mm-sized silica beadsand SiO dust as simulants In our free-fall chambers we obtaincollision velocities ranging from 1 to 200 cm s for 1-2 cmaggregates with pressures ~01 mbars We measure coefficients ofrestitution sticking thresholds and fragmentation thresholdsthen compare the results of our experiments with numericalsimulations using a collisional N-body code We find that cm-sizedagglomerates made up of mm-sized particles (or of mm-sizedaggregates of micron sized SiO dust) are very weakly bound andrequire high porosity and internal cohesion to avoid fragmentationin agreement with both simulations and collision experiments Thevelocity threshold for sticking is found to be near 7 cm s far fromthe fragmentation threshold of ~1 m s for cm-sized bodiesQuiescent regions in the mid-plane of the disk may cultivateabnormally low relative velocities permitting sticking to occur (~1cm s ) however without a well-defined path to formation it isdifficult to determine whether collisional accretion as a mechanismcan overcome low thresholds for sticking and fragmentation Wediscuss this researchrsquos implications to both the meter-barrier andplanetesimal formation

Author(s) Akbar Whizin Joshua E Colwell Juumlrgen Blum Mark C LewisInstitution(s) 1 Technische Universitaumlt Braunschweig 2Trinity University 3 University of Central Florida

50702 ndash Global Evolution of Solids in the Nebula theRole of Porosity in Particle Growth and RadialMigrationPrimitive chondrite parent bodies apparently accreted over severalMyr during which time the nebula gas is expected to have evolvedsignificantly The extended range of radioisotope ages observed forprimitive body formation can then best be explained if the nebulawere weakly turbulent this environment frustrates planetesimalformation but millimeter-to-meter-size particles can grow bysticking and possibly undergo substantial inward radial migrationbefore being destroyed by mutual collisions or evaporating in awarmer environment This migration can lead to a significantredistribution of the nebula condensibles relative to the evolvinggas challenging the popular concepts of minimum mass nebulaand local cosmic abundance Moreover as drifting particlestransform from solid to vapor at evaporation fronts they canfundamentally change the nebula chemical and isotopiccomposition Yet the problem of primary accretion remainscomplicated because although even moderate turbulence canextend the period of accretion over those implied by the meteoriterecord it may do so too well Estrada et al (2015 submitted to ApJarXiv150601420) have found that particle sizes are so readilyrestricted by the combination of bouncing fragmentation andradial drift over the range of models studied that much of thenebula solids can be removed from the outer portions of the diskand become concentrated in the inner regions in relatively shorttimescales where they may eventually be lost altogether The rapidclearing of the outer disk is due to growth not being fast enough toovercome the radial drift barrier However only solid particles wereconsidered Fractal growth by low velocity sticking of smallmonomers will cause the particles to have a much lower densitythan the monomers themselves Coupled with the stickiness andstrength of icy particles we expect that these fluffy aggregates can

2 24 2 3 2

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grow large but maintain low relative velocities allowing forcontinued growth without compaction Here we assess whether theconsideration of particle porosity particularly outside the snowline may allow for particles to overcome the radial drift barrier andpotentially grow into larger bodies

Author(s) Paul R Estrada Jeffrey N CuzziInstitution(s) 1 NASA Ames Research Center 2 SETI Institute

50703D ndash Planetary growth by the accretion ofpebblesPebbles approximately cm-sized solids that drift through aprotoplanetary disc provide a reservoir of material that can beefficiently accreted by planetary embryos due to the dissipatingeffect of gas drag (Lambrechts amp Johansen 2012)Here we will highlight the robust implications of pebble accretionon the formation of planets throughout the protoplanetary discIn the outer disc icy pebbles form by coagulation and consequentlystart drifting inwards Nevertheless we find that the pebble surfacedensities are sufficiently high to form giant planets on wide orbitsbefore the gas disc disperses after a few Myr (Lambrechts ampJohansen 2014) Growth is only halted when cores reach sizes ofaround 10 Earth masses when their gravity creates pressurebumps trapping the inwards drifting pebblesThis accretion cutofftriggers the attraction of a massive gaseous envelope Additionallythe fast growth of giant planets prevents the loss of the cores bytype-I migration (Lambrechts et al 2014 Bitsch et al 2015)Closer to the star interior to the ice line pebble accretion takes ona different form There chondrule-sized particles lead to theformation of much smaller Mars-sized embryos before the pebbleflux is terminated by the growth of the gas giants (Morbidelli et al2015) We will also discuss ongoing work on the conditions underwhich much larger Super-Earths can form

Author(s) Michiel Lambrechts Anders Johansen BertramBitsch Alessandro MorbidelliInstitution(s) 1 Lund University 2 Observatoire de la CocirctedAzur

50704 ndash Early Solar System Leftovers Testing SolarSystem Formation ModelsOne of the most intriguing predictions of the Grand Tack model isthe presence of volatile poor objects in the Oort cloud that wereswept from the region where the terrestrial planets formed Thisvolatile-poor material is represented today by ordinary chondritesenstatite chondrites and differentiated planetesimals These are themain constituents of the S-type asteroids that reside in the innerSolar system According to the Grand Tack model the fraction ofS-type material in cometary orbits should be around 01-02Recent Pan-STARRS 1 discoveries of objects on long-period cometorbits that are minimally active while at small perihelia havesuggested the intriguing possibility that these could potentiallyrepresent inner solar system material that was ejected into theouter solar system during planet migration that is now making itsway back in The first object discovered C2013 P2 has a spectrumredder than D-type objects but exhibits low-level activitythroughout its perihelion passage The second one C2014 S3appears to have an S-type asteroid spectrum and likewise exhibitslow-level activityNearly 100 of these objects have now been identifiedapproximately half of which are still observable and more are beingdiscovered We will report on observations made for a selection ofthese objects with several facilities including Gemini N 8 m VLT 8m Canada-France-Hawaii 36 m PS1 2 m UH22 m HCT 2 m andthe Lowell 18 m telescopes We will discuss the implications ofseeing volatile activity in these objects

Author(s) Karen Jean Meech Bin Yang Jan Kleyna Olivier R Hainaut Jacqueline V Keane Marco Micheli Svetlana Berdyugina Bhuwan Bhatt Devendra Sahu HenryHsieh Peter Veres Richard J Wainscoat Timm-EmanuelRiesen Heather KalunaInstitution(s) 1 European Southern Observatory 2 IndianInstitute of Astrophysics 3 Institute for Astronomy 4 Institute ofAstronomy amp Astrophysics Academia Sinica 5 Kiepenheuer-Institut fur Sonnenphysik 6 SSA NEO Coordination Centre ESA7 University of Bern

50705 ndash The effects of the formation of a giant planeton the evolution of the protoplanetary disk the caseof Jupiter in the Solar SystemThe formation of a giant planet is one of the milestones in the lifeof a planetary system as it plays a leading role in shaping itssubsequent evolution Once the core of the forming giant planetreaches the critical mass needed to trigger the hydrodynamicalinstability in the surrounding nebular gas and start the rapid phaseof gas accretion the planetary system in which the planet isembedded suddenly experience the appearance of a stronggravitational perturber Even in absence of migration this eventwill trigger a 05-1 Myr-long phase of violent remixing andenhanced collisional evolution of the planetary bodies in theprotoplanetary disk For what it concerns the giant planet itselfthis primordial bombardment will result in the capture of high-Zmaterial from a wide orbital range including the inner regions ofthe planetary system For what it concerns the other bodies of theprotoplanetary disk this phase of remixing and bombardment willresult in the collisional erosion of the smallest planetesimals in thedynamically-excited orbital regions and in the delivery of water andvolatile elements to the inner regions of the planetary systemWhile the mass growth of the giant planet is necessary andsufficient condition to trigger this primordial bombardmentplanetary migration plays a major role in determining its intensityUsing the formation of Jupiter in the Solar System as our casestudy we will illustrate how this event affects the Jovian systemand the asteroid belt Concerning the latter we will also discusshow the composition of asteroid Vesta whose formation anddifferentiation predate the formation of Jupiter suppliesinformation on the primordial dynamical evolution of the giantplanet

Author(s) Diego TurriniInstitution(s) 1 Institute for Space Astrophysics andPlanetology INAF-IAPS

50706 ndash In-situ Formation of Mars-like Planets -Results from Hundreds of N-body Simulations ThatInclude Collisional FragmentaionDynamical simulations of the formation of the Solar System havebeen successful at reproducing the broad characteristics of theterrestrial planets however they have consistently struggled toreproduce the small mass of Mars within the timescale provided bygeochemical constraints This has prompted the development ofnew models that invoke various mechanisms such as giant planetmigration that result in the formation a small Mars Due primarilyto the computationally intensive nature of these models mostprevious studies were based on a small (less than a dozen) numberof simulations and did not include the effects of collisionalfragmentation However these systems are highly stochastic andrequire a large number of simulations in order to infer the resultsin a statistical manner Here we show that by performing 150N-body simulations of terrestrial planet formation around the Sunthat include collisional fragmentation the formation ofMars-analogs is a natural outcome albeit not a common oneApproximately 13 of the simulations produced a Mars-sizedplanet near Marsrsquo current orbit that accreted at least 90 of itsmass within 3 Myr The current architecture of the planets in ourSolar System can be thought of as one draw from a distribution ofplanetary systems that can form from essentially the sameprotoplanetary disk These results support the idea that Mars mayessentially be a stranded embryo that survived the giant impactphase without a significant amount of accretion or erosion but that

2 1

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it need not be the only outcome from the chaotic process offorming planets

Author(s) Thomas Barclay Elisa V QuintanaInstitution(s) 1 NASA Ames Research Center

50707 ndash Determining the Location of the Snowline inan Externally-Photoevaporated Solar NebulaThe water snowline in the solar nebula the point beyond whichwater exists abundantly as ice is often taken to lie at 27 AU fromthe Sun where temperatures are ~170 K the sublimation point ofwater [12] While superficially consistent with the spatialdistribution of (wet) C-type and (dry) S-type asteroids between2-3AU [3] most disk models place the snowline closer to ~1AU [4]Aside from temperature radial transport and outward diffusion ofwater vapor and the inward drift of ices also determine where thesnowline is [56] Over many Myr a steady cycling of water inwardand outward across the T=170 K line balance out with anenhanced ice abundance outside creating the lsquosnowlinersquo[2] Butexternal effects like photoevaporation of the nebula by nearbymassive stars can potentially shift this balance lead to net outwardwater vapor transport from the inner nebula [78] pushing thesnowline beyond T=170 K thus giving rise to water-poor planetsTo test this hypothesis we have first built a 1+1D protoplanetarydisk evolution model incorporating viscosity due to themagnetorotational instability with a non-uniform turbulentviscosity α across disk radius r ionization equilibrium with dustand external photoevaporation [8] Our simulation results suggestthat the structure of the photoevaporated solar nebula with anon-uniform α(r) was more complex than previously thought withthe following features (i) very steep Σ profile (Σ(r)=Σ r whereslope p = 3ndash5 gt p =15) due to the varying α(r) that isfurther steepened by the effect of dust and photoevaporation and(ii) transition radius (where net disk mass flow changes frominward flow to outward) that is present very close to the star(~3AU) We apply these new results to study the distribution ofwater in the solar nebula References [1] Hayashi C (1981)PThPSupp 70 35-53 [2] StevensonD amp LunineJ (1988) Icarus75 146-155 [3] Gradie J amp Tedesco E(1982) Science 2161405-1407 [4] Sasselov DD amp Lecar M (2000) ApJ 528995-998 [5] Cuzzi J N amp Zahnle K J (2004) ApJ 614 490-496[6] Ciesla F J amp Cuzzi J N (2006) Icarus 181 178-204 [7]Desch SJ(2012)LPSC abstract 2770 [8] Kalyaan A et al(inreview)

Author(s) Anusha Kalyaan Steven DeschInstitution(s) 1 Arizona State University

50708 ndash Nebular dead zone effects on the DH ratio inchondrites and cometsComets and chondrites show non-monotonic behaviour of theirDeuterium to Hydrogen (DH) ratio as a function of theirformation location from the Sun This is difficult to explain with aclassical protoplanetary disk model that has a decreasingtemperature structure with radius from the SunWe want to understand if a protoplanetary disc with a dead zone aregion of zero or low turbulence can explain the measured DHvalues in comets and chondrites We use time snapshots of avertically layered disk model with turbulent surface layers and adead zone at the midplane The disc has a non-monotonictemperature structure due to increased heating from self-gravity inthe outer parts of the dead zone We couple this to a DH ratioevolution model in order to quantify the effect of such thermalprofiles on DH enrichment in the nebulaWe find that the local temperature peak in the disk can explain thediversity in the DH ratios of different chondritic families This disktemperature profile leads to a non-monotonic DH enrichmentevolution allowing these families to acquire their different DHvalues while forming in close proximity The formation order weinfer for these families is compatible with that inferred from theirwater abundances However we find that even for very youngdisks the thermal profile reversal is too close to the Sun to berelevant for comets[1] Ali-Dib M Martin R G Petit J-M Mousis O Vernazza P

and Lunine J I (2015 in press AampA) arXiv150800263

Author(s) Mohamad Ali-Dib R G Martin J-M Petit OMousis P Vernazza J I LunineInstitution(s) 1 Aix Marseille Universiteacute CNRS LAM(Laboratoire drsquoAstrophysique de Marseille) UMR 7326 2 Centerfor Radiophysics and Space Research Space Sciences BuildingCornell University 3 Department of Physical amp EnvironmentalSciences University of Toronto at Scarborough 4 Department ofPhysics and Astronomy University of Nevada 5 Universiteacute deFranche-Comteacute Institut UTINAM CNRSINSU UMR 6213Observatoire de Besanccedilon

50709 ndash C O (x=161718) isotopologue ratios in thesolar photosphereDetermination of the oxygen isotope ratios in the solarphotosphere is essential to constraining the formationenvironment of the solar system The solar CO fundamental andfirst-overtone bands were previously measured by theshuttle-borne ATMOS Fourier transform spectrometer (FTS) andwith the National Solar Observatory FTS on the McMath-Piercetelescope at Kitt Peak Analyzing the rovibrational bands fromthese photospheric spectra a 3D convection model was employedto calculate ratios with improved uncertainties( O O=2738plusmn118 and O O =511plusmn10 Ayres et al 2013)which fall between the terrestrial values and those inferred fromsolar wind measurements by the Genesis spacecraft Howeverdifferences in published CO dipole moment functions yielded arange of isotopic ratios spanning ~ 3 in δ O Here were-evaluate the CO dipole moment function in order to obtain moreaccurate isotope ratios for the photosphere We used a new set ofdipole moments from HITEMP which were accurately determinedby both semi-empirical and ab initio methods Preliminary valuesof isotope ratios using the new dipole moments are in betteragreement with the inferred photosphere values from Genesisshowing that the solar photosphere is isotopically similar toprimitive inclusions in meteorites but different from the terrestrialplanets by ~ 6 New spectral observations are needed to reduceuncertainties in photospheric C O abundances

Author(s) James Lyons Ehsan Gharib-Nezhad ThomasAyresInstitution(s) 1 Arizona State University 2 University ofColorado

50710 ndash Consolidating and Crushing Exoplanets DidIt Happen HereKepler revealed the common existence of tightly-packedsuper-Earth systems around solar-type stars existing entirelyinside the orbit of our Venus Those systems must be stable for theages of their host stars (~10^9 years) their formation mechanismmust provide inter-planet spacings that permit long-term stabilityIf one postulates that most planetary systems form with tightly-packed inner planets their current absence in some systems couldbe explained by the collisional destruction of the inner system aftera period of meta-stabilityWe posit that our Solar System also originally had a system ofmultiple planets interior to the orbit of Venus This would resolve aknown issue that the energyangular momentum of our inner-planet system is best explained by accreting the current terrestrialplanets from a disk limited to 07-11 AU in our picture the diskmaterial closer to the Sun also formed planets but they have sincebeen destroyed By studying the orbital stability of systems like theknown Kepler systems we demonstrate that orbital excitation andcollisional destruction could be confined to just the inner parts ofthe system In this scenario Mercury is the final remnant of theinner systems destruction via a violent multi-collision (andorhit-and-run disruption) process This would provide a naturalexplanation for Mercurys unusually high eccentricity and orbitalinclination it also fits into the general picture of long-timescalesecular orbital instability with Mercuryrsquos current orbit beingunstable on 5 Gyr time scales The common decade spacing ofinstability time scales raises the intriguing possibility that thisdestruction occurred roughly 06 Gyr after the formation of our

1 1

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MMSN

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16 17 16 18

18

17

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174

Solar System and that the lunar cataclysm is a preserved record ofthis apocalyptic event that began when slow secular chaosgenerated orbital instability in our former super-Earth system

Author(s) Brett Gladman Kathryn VolkInstitution(s) 1 Univ of British Columbia

50711 ndash Exoplanet Population Estimate from KeplerDataThe intrinsic population of exoplanets around Kepler target stars isestimated by comparing the observed numbers of planets at eachradius and period against a simulation that accounts for theprobability of transit and the estimated instrument sensitivity Byassuming that the population can be modeled as a function ofperiod times a function of radius and further assuming that thesefunctions are broken power laws sufficient leverage is gained suchthat the well-measured short-period planet distribution caneffectively be used as a template for the less-well sampledlong-period terrestrial planets The resulting populationdistribution provides a challenge to models of the origin andevolution of planetary systems

Author(s) Wesley A TraubInstitution(s) 1 Jet Propulsion Laboratory

508 ndash Icy Satellites50801 ndash From One Come Many A diversity of craterpopulations from a single impacting population withapplication to the Saturnian (and Galilean) SatellitesWe present our recent analyses that quantify the spatial andsize-frequency distribution (SFD) of crater populations on themid-sized Saturnian (and Galilean) satellites The resultsdemonstrate that a single-sized impactor will generate both (i)different-sized primary craters on the icy satellites and (ii)observably different secondary crater populations (both in terms ofSFDs and spatial distributions) between the satellitesRelative magnitude of secondaries and their SFDs The number ofsecondary craters generated by a primary impact is a function of thesize of the primary crater v_min the minimum speed needed tomake a secondary and v_esc the escape speed of the target bodyThe primary crater size controls the amount of ejected materialv_min defines the lower limit of that ejected mass that can makesecondaries and v_esc defines the upper limit of the mass that canmake secondaries (ie material that escapes the target body cannotmake secondaries) Because a single-sized impactor will makedifferent-sized primaries on each of the satellites (resulting indifferent masses available to make secondaries) and v_esc alsovaries between the satellites different amounts of ejecta areavailable to make secondaries Because surface gravity is a factor inthe size of a crater a given-sized ejecta fragment will make adifferent-sized secondary on the satellites even given the sameimpact speedSpatial distribution of secondaries Because of varying surfacegravities g of planetary bodies a given ejectum speed will launch afragment different distances In conjunction with v_min thespatial density of adjacent secondaries (or even their existence) willvary depending on surface gravity At progressively smaller gv_min results in greater distances and dense annular clusterssurrounding the primary crater wonrsquot appear except for the largestprimary craters On the lower-g objects v_min corresponds totravel distances that are significant fractions of the objectrsquoscircumference Ejecta that make adjacent secondaries on a higher-gobject may make a significant population of backgroundsecondaries on low-g objects

Author(s) Edward B Bierhaus Luke Dones StuartRobbinsInstitution(s) 1 Lockheed Martin 2 Southwest ResearchInstitute

50802 ndash Crustal Failure in Large Icy Bodies from aStrong Tidal Encounter

Close tidal encounters among large planetesimals and satellites aremore common than grazing or direct impacts Using a mass springmodel simulation we look at the deformation of the surface of anelastic spherical body caused by a nearly parabolic close tidalencounter with a body that has mass similar to that of the primarybody We delineate a regime for tidal encounters that inducesufficient stress on the surface for brittle failure of an icy crustSimulated cracks caused by extension of the crust extend a largefraction of the radius of body Tidal encounters give an alternativemechanism for formation of long graben complexes and chasma onicy satellites such as Dione Tethys Ariel and Charon

Author(s) Alice C Quillen David Giannella John ShawInstitution(s) 1 Laboratory for Laser Energetics 2 Univ ofRochester

50803 ndash Discovering sub-micron ice particles acrossDione surfaceWater ice is the most abundant component of Saturnrsquos mid-sizedmoons However these moons show an albedo asymmetry ndash theirleading sides are bright while their trailing side exhibits darkterrains Such differences arise from two surface alterationprocesses (i) the bombardment of charged particles from theinterplanetary medium and driven by Saturnrsquos magnetosphere onthe trailing side and (ii) the impact of E-ring water ice particles onthe satellitesrsquo leading side As a result the trailing hemisphereappears to be darker than the leading side This effect is particularlyevident on Diones surface A consequence of these surfacealteration processes is the formation or the implantation ofsub-micron sized ice particlesThe presence of such particles influences and modifies thesurfaces spectrum because of Rayleigh scattering by the particlesIn the near infrared range of the spectrum the main sub-micronice grains spectral indicators are (i) asymmetry and (ii) long wardminimum shift of the absorption band at 202 μm (iii) a decreasein the ratio between the band depths at 150 and 202 μm (iv) adecrease in the height of the spectral peak at 26 μm (v) thesuppression of the Fresnel reflection peak at 31 μm and (vi) thedecrease of the reflection peak at 5 μm relative to those at 36 μmWe present results from our ongoing work mapping the variationof sub-micron ice grains spectral indicators across Dione surfaceusing Cassini-VIMS cubes acquired in the IR range (08ndash51 μm)To characterize the global variations of spectral indicators acrossDione surface we divided it into a 1degx1deg grid and then averaged theband depths and peak values inside each square cellWe will investigate if there exist a correspondence with water iceabundance variations by producing water ice absorption banddepths at 125 152 and 202 μm and with surface morphology bycomparing the results with ISS color maps in the ultraviolet visibleand infrared ranges Finally we will compare the results with thoseobtained for Enceladus Tethys and Mimas

Author(s) Francesca Scipioni Pual Schenk FedericoTosi Roger Clark Cristina Dalle Ore Jean-Philippe CombeInstitution(s) 1 Bear Fight Institute 2 INAFIAPS 3 Lunarand Planetary Institute 4 PSI 5 SETI

50804 ndash High energy electron processing of icyregoliths on Saturns moonsA unique space weathering phenomenon has been identified onseveral icy Saturnian moons Cassini revealed anomalous lensshaped regions in both optical and thermal wavelengthscolloquially known as the PacMan feature which are centered onthe leading hemispheres and approximately symmetric about theequators In particular the Cassini InfraRed Spectrometer (CIRS)measurements of thermal emission in the mid-IR showed thatsurface temperature variations during a diurnal cycle were smallerinside the anomalous regions The locations of the anomalies wereshown to closely match the expected deposition profile of highenergy (~ MeV) electrons moving counter rotational to the moonssuggesting an energetic source to drive their formation Howeverthe mechanisms by which thermal conductivity enhancementoccur lack quantitative comparison with theoretical andexperimental results

1 1

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Electron interactions with the grains can excite molecules which ifnear enough to an intergrain contact can cause atoms or moleculesto migrate into the contact region thus increasing the contactvolume or sintering the grains Sintering improves the thermalcontact between grains leading to increased effective thermalconductivity of the regolith Equations previously developed todescribe material behavior in nuclear reactor were used to estimatethe timescale for the energetic electrons to increase the contactvolume sufficiently to describe the enhanced thermal conductivityof the anomalous regions In order to properly constrain thesintering calculations the unique electron energy distributionmeasured in the vicinity of each of the moons was used in thecalculations and molecular dynamics simulations of excitedelectrons in water ice were carried out to determine the length scalefor an average electron excitation or ionization event This lengthscale determines the distance from the primary reaction at whichelectrons can still be mobilized to move into the contact region Thesintering timescales were compared to published values formicrometeorite resurfacing rates in order to determine if electroninduced sintering can create a stable equilibrium on the surface ofthe moons

Author(s) Micah Schaible Robert E JohnsonInstitution(s) 1 University of Virginia

50805 ndash Coherent Backscattering Effect in Saturnianvs Uranian Satellites Effects on Band Depths andShapesIn this work we examine the changes in depth and shape ofindividual absorption bands as a function of solar phase angle thatare caused by the coherent backscattering effect (CBE) in near-IRspectra of saturnian and uranian satellites We have quantifiedband depths and shapes for real-world data (from Cassini Visual ampInfrared Mapping Spectrometer (VIMS) and TripleSpec at ApachePoint Observatory) and also modeled spectra of densely packed icyparticulate surfaces with the MSTM (multisphere T-matrix) version40 code specifically developed to model light scattering in regolithlayers MSTM4 allows us to calculate the brightness for thick fluffylayers on order of 20000 particles (compared to 1000 withprevious code versions) We have now obtained good matchesbetween model and real-world data at specific bands for severalhigher albedo moons We are finding that the normalized depth ofthe absorption band can increase or decrease with solar phaseangle depending on the albedo at the wavelength of normalizationthis is seen in all the data (VIMS ground-based and modelspectra) We model the change in the phase-angle-dependent banddepth in response to varying the size and packing of the constituenticy particles Indeed the coherent backscattering effect can beobserved at some wavelengths and entirely disappear at othersbecause CBE requires a specific range of size and packing (cfMuinonen et al 2014) we see this effect as wellThis work is supported by NASArsquos Outer Planets Research program(NNX12AM76G PI Pitman) Planetary Astronomy program(NNX09AD06G PI Verbiscer) and NASArsquos AdvancedSupercomputing Division Calibrated Cassini VIMS data cubesappear courtesy of the Cassini VIMS team and the PDS

Author(s) Karly M Pitman Ludmilla Kolokolova Anne JVerbiscer Charles Gulotta Emily C S Joseph Daniel WMackowski Bonnie J Buratti Thomas W MomaryInstitution(s) 1 Auburn University 2 Jet PropulsionLaboratory California Institute of Technology 3 PlanetaryScience Institute 4 Space Science Institute 5 University ofMaryland 6 University of Virginia

50806 ndash Charging and Discharging of AmorphousSolid Water Ice Effects of PorosityIntroduction Amorphous solid water (ASW) is abundant onSaturnrsquos icy satellites and rings [12] where it is subject tobombardment of energetic ions electrons and photons togetherwith secondary electron and ion emission this may leave thesurfaces charged Surface potential can affect the flux of incomingcharged particles altering surface evolution We examined the roleof porosity [3] on electrostatic charging and discharging of ASW

films at 30ndash140 KExperiment Experiments were performed in ultra-high vacuum[4] ASW films were deposited at 30 K onto a liquid-He-cooledquartz crystal microbalance (QCM) Film porosity was calculatedfrom the areal mass via the QCM and thickness via a UV-visibleinterferometry ASW films were charged at 30 K using 500 eV He Surface potentials (V ) of the films were measured with a Kelvinprobe and infrared spectra were collected using a Fouriertransform infrared spectrometerResults We measured V of the ASW film at 30 K as a function ofion fluence (F) The V (F) deviates from a straight line at lowfluence attributed to emitted secondary electrons due to thenegative polarization voltage [56] and increases linearly when theV is positive We also measured V as a function of annealingtemperature We prepared ASW films with various porosities byannealing the films to different temperatures (T ) prior toirradiation or varying the vapor-beam incidence angle (θ) Uponheating we observed sharp decreases of the V at temperaturesthat strongly depend on T and θ Decreases of the infraredabsorbance of the dangling OH bands of the charged film sharesimilar trends as that of the V We propose a model that includesporosity for electrostatic chargingdischarging of ASW films attemperatures below 100 K Results are applicable to the study ofplasma-surface interactions of icy satellites and ringsReferences [1] Jurac et al J Geophys Res 100 14821 (1995)[2] A L Graps et al Space Sci Rev 137 435 (2008) [3] U Rautet al J Chem Phys 127 204713 (2007) [4] C Bu and R BBaragiola J Chem Phys 143 074702 (2015) [5] C Bu et al JChem Phys 142 134702 (2015) [6] M J Iedema et al J PhysChem B 102 9203 (1998)

Author(s) Caixia Bu Raul A BaragiolaInstitution(s) 1 University Of Virginia

50807D ndash Porosity effects on crystallization kineticsof Amorphous Solid Water Implications for cold icyobjects in the Outer Solar SystemCrystalline ice has been identified on the cold surfaces of most icysatellites and TNOs [1] This is surprising since accretion of watervapor at temperatures (T lt 100 K) should result in the amorphousphase [2] There are several possible explanations for theunexpected presence of crystalline ice on cold bodies includingcryovolcanism [3] and pulsed heating by micrometeoritic impacts[4]A salient feature of ice films condensed at low T is microporosityknown to increase with deposition angle [5] Here we investigatethe dependence of the crystallization rate on the ice porosity whichcould contribute to the observed variation in crystallization time τreported in the literature [2] Such dependence is noted in otherporous materials such as zeolites and titania [6 7]Amorphous ice films were deposited on a CsI substrate from acollimated water vapor source at 10 K at incidences varying from 0to 70deg as well as from an omnidirectional water vapor source Thefilms were heated to temperatures between 130 and 140 Kfollowing deposition The isothermal transition from amorphous tofully crystalline phase was characterized by analyzing thetime-dependent evolution of the OH-stretch absorption band usingtransmission infrared spectroscopy Our initial results show that τdecreases with increasing porosity for instance a film deposited at45deg was observed to crystallize ~6 times faster than a film depositedat 0deg The preliminary estimate of the porosity of the 45deg film is~50 higher than that of the film deposited at normal incidenceOur findings can explain the reported variation in temperature-dependent τ [2] and contribute to the understanding of crystallineice on cold bodies in the Outer Solar System1 Mastrapa RME et al In Gudipati MS amp Castillo-Rogez JEds The Science of Solar System Ices Springer New York 20132 Baragiola RA In Devlin amp Buch Eds Water in ConfiningGeometries Springer-Verlag 20033 Jewitt DC amp Luu J Nature 432 731 20044 Porter SB et al Icarus 208 492 20105 Stevenson KP et al Science 283 1505 19996 Francis RJ amp OrsquoHare D J Chem Soc Dalton Trans 31331998

1 1

4 56 5 3

1 2 2

+

s

ss

s s

a

sa

s

1 1

c

c

c

176

7 Kirsch BL et al J Phys Chem B 108 12698 2004

Author(s) Emily H Mitchell Ujjwal Raut Raul ABaragiolaInstitution(s) 1 University of Virginia

50808 ndash Identifying new surface constituents of icymoons using mid-infrared spectroscopySpectroscopic compositional studies of the icy satellites can help usto better understand the formation and evolution of material in theouter solar system The spectral complexity of the Saturniansatellite system as seen in reflected visible light suggests additionalcomplexity may be present at mid-infrared wavelengths from whichunique compositional information can be gleaned [1] In additionthe mid-infrared is the region of the stronger fundamentaldiagnostic vibrational modes of many compounds HoweverCassini Composite Infrared Spectrometer (CIRS) surfacecompositional studies have received little attention to dateWe are exploring the suitability of mid-infrared spectroscopy fordiscovering non-H O compounds on icy moon surfaces On thedark terrain of Iapetus we find an emissivity feature at ~855 cmand a potential doublet at 660 and 690 cm that do not correspondto any known instrument artifacts [2] We attribute the 855 cmfeature to fine-grained silicates similar to those found in dust onMars and in meteorites which are nearly featureless at shorterwavelengths [3] Although silicates on the dark terrains of Saturnrsquosicy moons have been suspected for decades there have been nodefinitive prior detections Serpentines measured at ambientconditions have features near 855 cm and 660 cm [4]However peaks can shift depending on temperature pressure andgrain size so measurements at Iapetus-like conditions arenecessary for more positive identifications [eg 5]We measured the vacuum low temperature (125 K) spectra ofvarious fine-grained powdered silicates We find that some of thesematerials do have emissivity features near 855 cm and match thedoublet Identifying a specific silicate would provide clues into thesources and sinks of the dark material in the Saturnian system Wereport on our ongoing exploration of the CIRS icy moon datasetand plans for future measurements in JPLrsquos Icy Worlds SimulationLab[1] Flasar FM et al (2004) Space Sci Rev 115 169[2] Young CL et al (in review) ApJ Lett[3] Christensen PR et al (2004) Sci 306 1733[4] Bishop JL et al (2008) Clay Minerals 43 35[5] Wray JJ et al (2014) DPS 46th Meeting Vol 46

Author(s) Cindy L Young James J Wray Kevin P Hand Michael J Poston Robert W Carlson Roger N Clark John RSpencer Donald E JenningsInstitution(s) 1 California Institute of Technology 2 GeorgiaInstitute of Technology 3 Jet Propulsion Laboratory 4 NASAGoddard Space Flight Center 5 Planetary Science Institute 6Southwest Research Institute

50809 ndash Composition and evolution of Tritons icysurface between 2002-2014 from SpeXIRTFWe observed Triton in the near-infrared (07-25 μm) over 63nights using the SpeX instrument at NASAs Infrared TelescopeFacility (IRTF) between 2002 and 2014 Tritonrsquos spectrum hasabsorption features due to N CO CH CO and H O in thiswavelength range We calculated the equivalent width (or fractionalband depth for H O) of select absorption bands in each of the 63night-averaged spectra Longitudinal distributions for the volatileices (N CO CH ) show large rotational amplitude while thenon-volatile ices (CO H O) show little amplitude over one Tritonrotation Absorption from N and CH increased over the period ofthe observations whereas absorption from the non-volatile icesremained constant The sub-solar latitude on Triton is currently at-42 degrees south so some areas of Triton are visible for a fullrotation Combined with our findings this suggests that thesouthern latitudes are dominated by non-volatile ices with largerconcentrations of volatile ices found in the observable region northof the equator Changing viewing geometry over the period of the

observations explains the increase in volatile absorption As thesub-solar point moves northwards more of the volatile-richnorthern regions are coming directly into view Geological evidencefrom Voyager 2 pointed to a southern hemisphere dominated byvolatile ices significant changes have occurred over the interveningquarter century

Author(s) Bryan J Holler Leslie A Young William MGrundy Cathy B OlkinInstitution(s) 1 LASP 2 Lowell Observatory 3 SouthwestResearch Institute

50810 ndash The Surprisingly Short Rotation Period ofHiiaka Haumeas Largest SatelliteThe dwarf planet Haumea stands out from the rest of its KuiperBelt counterparts with its rapid rotation two satellites andassociated collisional family of small objects The larger outersatellite Hiiaka orbits Haumea with a period of 49462 days aneccentricity of 005 and an inclination of ~2 degrees If it formedlike a regular satellite and tidally evolved to its current location itwould be expected that Hiiaka would be tidally despun HoweverHST and Magellan ground based data show that Hiiaka shows a20 peak-to-peak brightness variability from which we havedetermined that Hirsquoiakarsquos rotation period is ~98 hours (double-peaked) The spin period is ~120 times faster than its orbital periodand too fast to be caused by standard mechanisms (eg spin-orbitresonance or chaos) The unusual spin rate also suggests thatHirsquoiaka could be the only known regular satellite to have asignificant free obliquity (as opposed to forced obliquity) Thisobliquity would result in stable spin axis precession We haveinvestigated the observability of Hiiakas spin precession bydetermining how the angle between the Earth line of sight and thespin axis direction changes over a precession cycle for variousobliquities If the obliquity is significant the resulting light curveevolution would be detectable within a ~decade We will presentthese results and discuss their implications for the formation ofHiiaka and Haumea

Author(s) Danielle M Hastings Darin Ragozzine Daniel CFabrycky Luke D Burkhart Michael E Brown Cesar Fuentes Matthew J HolmanInstitution(s) 1 California Institute of Technology 2 FloridaInstitute of Technology 3 Harvard University 4 Harvard-Smithsonian Center for Astrophysics 5 Universidad de Chile 6University of Chicago

50811 ndash Orbital analysis of the inner Uraniansatellites from Hubble imagesThe thirteen inner moons of Uranus form a densely-packed andpossibly chaotic system Numerical simulations show that severalgroups of moons exhibit complex resonant interactions and Mabshows as-yet unexplained variations in its orbit However themasses of these moons are currently unknown limiting theinsights that can be gained from numerical simulations Using over650 long-exposure images taken during 2003-2013 by the HubbleSpace Telescope through broadband filters we have obtainedastrometry for eleven of Uranusrsquos inner moons comprising thePortia group (Bianca to Perdita) plus Puck and Mab attempts tomeasure the positions of Cordelia and Ophelia are on-going Usingthese measurements which are frequently accurate to 005 pixelsor less we have derived Keplerian orbital elements including theinfluence of Uranusrsquos oblateness The elements show year-to-yearvariations that are statistically significant and indicate the role ofmutual perturbations among the moons We are also using thisinformation to place new constraints on the masses of thesemoons We will present our most recent findings

Author(s) Robert S French Mark R Showalter Imke dePater Jack J LissauerInstitution(s) 1 NASA ARC 2 SETI Institute 3 University ofCalifornia Berkeley

1 11

2-1

-1-1

-1 -1

-1

2 2 31 3 5

6 4

2 4 2 2

2

2 42 2

2 4

1 32 3

2 26 3 1 5

4

2 23 1

177

Authors IndexAbell Paul 31206Acton Charles Hall 31205Adamkovics Mate 20505Adams Elisabeth R 50102Ahlers Johnathon 41705Akeson Rachel L 41701Albers Nicole 21807Albin Edward F 21919Alcock Charles 31207Ali-Dib Mohamad 50708Altwegg Kathrin 50301Anderson Carrie 30001Angelo Isabel 41703Arevalo Ricardo 31211Armstrong Eleanor Sophie31130Arney Giada 40402Auger Anne-Theacuteregravese 50003Aye Klaus-Michael 42001Backman Dana E 31217Badhan Mahmuda A 41617Bagenal Fran 10006Bailey Jeremy 41616Baines KH 40005Banfield Don 40108Banks Maria E 21506Bannister Michele T 20304Barclay Thomas 50706Bardyn Anais 50308Barentsen Geert 30821Barnes Jason W 41805Barnouin Olivier S 40209Barth Erika L 30002Battalio Joseph 40105Batygin Konstantin 30708Bauer James M 41501Becker Tracy M 10403DBell James F 31208Bell Jared M 41921Bellotti Amadeo 40304Benecchi Susan D 2110321906Benner Lance A M 20407Beacuterard Diane 10402Bering Edgar Andrew 2191231210Bertrand Tanguy 21020Beyer Ross A 10206Bhattacharyya Dolon 41902Bierhaus Edward B 50801Binzel Richard P 30103Bjoraker Gordon 40306Blacksberg Jordana 30908Blalock John J 31108Bland Michael T 10307Blaney Diana L 42003Blum Juumlrgen 30201Blumenthal Sarah 50403Bodewits Dennis 50303Bonev Boncho P 50606Booth Shawn 41523Bosh A S 10503Bosh Amanda S 21031Bottke William 20107Bougher Stephen W 50505Bourzutschky Alexander40405Bowman M Oliver 30820Bradley Eric Todd 21503Brasil Pedro Ivo de Oliveira21401Brasunas John C 31216Brauer Kaley 21303

Brown Adrian J 21310Brown Linda R 31134Brown Michael E 21315Brown Peter G 40207Brown Zarah 21805Brozovic Marina 40206Brucker Melissa J 30707Bu Caixia 50806Buczkowski Debra 21204Buie Marc W 20003Bullock Mark A 21708Buratti Bonnie J 20004Burger Matthew H 21502Busch Michael W 40205Butler Bryan J 21004Buxner Sanlyn 21907Buxner Sanlyn R 21915Campins Humberto 10605Canup Robin M 30207Cao Hao 40301Capanna Claire 41311Carruba Valerio 20106Cartwright Richard J 41102Chaffin Michael S 50508Challener Ryan C 41605Chambers John E 41801Chan Kwing Lam 31129Chancia Robert O 21812Chang Chan-Kao 30711Chanover Nancy J 31202Charnay Benjamin 41615Charnoz Sebastien 30206Chatelain Joseph 30703Cheng Andrew F 10502Chesley Steven R 30809Chi Peter J 21709Chodas Paul 21409Chrenko Ondrej 41802Christensen Eric J 30819Christou Apostolos 10702Cibulkova Helena 30710Clancy R T 40107Clark Roger Nelson 40401Clarke John T 50507Cobb Whitney 21909Cochran William D 41702Colwell Joshua E 10410Combi Michael R 41314Cook Jason C 20002Cooper John F 10411Cordiner Martin 20503Corlies Paul 30007Corliss Jason B 41524Cosentino Rick 31120Cottini Valeria 31009Cotto-Figueroa Desireeacute21320Courtin Reacutegis 31010Coustenis Athena 31008Crismani Matteo MichaelJames 41918Crowell Jenna L 21304Cruikshank Dale P 10102Cuk Matija 30901Cull-Hearth Selby 42002Curry Shannon 50506DAngelo Gennaro 41806Dalba Paul A 50401Dalle Ore Cristina M 21027Dalton Heather 21920Davidsson Bjorn 41315Davies Ashley Gerard 40503Davighi Joseph E 40302

Dawson Rebekah Ilene30601 41704Day Brian 21602de Kleer Katherine R 40504de Leon Julia 10609de Pater Imke 40906Debes John H 41619Deckers Johannes 30202DDeighan Justin 50509Del Rio Gaztelurrutia Teresa31112DeLarme Emerson 41602Delitsky M L 21702Dello Russo Neil 41512DeMeo Francesca E 30108Denevi Brett W 20801Denk Tilmann 41202Desch Steven 21028DeVogel Kayla 31124Dhingra Deepak 41103Dhingra Rajani D 30008Dias-Oliveira Alex 20009DDiSanti Michael A 41510Dombard Andrew J 21208Domingue Deborah L 21312Dones Henry C (Luke)41520Dong Chuanfei 41913Drube Line 10604Drummond Jack D 21404Dukes Catherine 21508Dumas Christophe 31219Durda Daniel D 20202Earle Alissa M 20005Edgington Scott G 31125El Moutamid Maryame10405Elliott Joshua Peter 21813Elrod Meredith K 41914Ennico Kimberly 20008Erwin Justin 21017Espley Jared R 50504Esposito Larry W 10409Estrada Paul R 50702Faggi Sara 50604Fan Siteng 20509Farnham Tony L 41504Farnocchia Davide 41503Feaga Lori M 50306Feldman Paul D 50305Fernandez Yanga R 41507Filacchione Gianrico 50008Fischer Patrick D 40905Flasar F Michael 50207Fletcher Leigh N 50203Folonier Hugo Alberto 31017Forget Francois 10512Fornasier Sonia 50006Foster Andrew S 41606Fougere Nicolas 41306Frantseva Kateryna 21402Fraser Wesley Cristopher21115French Linda M 30705French Robert S 50811Friedson Andrew James31121Frouard Julien 30712Fry Patrick M 31101Fuentes Cesar 31212Gabriel Travis SJ 30904Gaertner Sabrina 30203Galanti Eli 40308

Gao Peter 50404DGarcia-Melendo Enrique40006Garland Justin 41604Garland Ryan 41601Gerakines Perry A 21030Giles Rohini Sara 40309Gladman Brett 50710Gladstone G R 10005Goguen Jay D 41105Goldspiel Jules M 40102Gordon Mitchell K 21804Gorius Nicolas 41001Gosmeyer Catherine 41613Granahan James C 21301Granvik Mikael 21407Grauer Albert D 21917Grav Tommy 30811Grava Cesare 10712Gray Candace L 20101DGreenberg Adam 30704Greenstreet Sarah 30812Greybush Steven J 41923Grier Jennifer A 21908Griffith Caitlin Ann 31016Gronoff Guillaume 41924Groussin Olivier 50005Grundy William M 1000420001Guerlet Sandrine 31117Guettler Carsten 41301Guimaratildees Ana HelenaFernandes 50106Gurwell Mark 10506Hadnott Bryne 30009Hahn Matthias 21029Hamilton Douglas P 20007Hammel Heidi B 31102Hammergren Mark 21314Hand Kevin P 40506Hansen Alexander K 21809Hansen Candice 41104Hanus Josef 30701Hardersen Paul S 10601Harrington Joseph 50406Hart Richard A 21701Hartig Kara 21014Hartwick Victoria 40104Hartzell Christine 20405Hastings Danielle M 50810Hayne Paul O 10309Hebrard Eric 41607Helled Ravit 31110Hendrix Amanda R 10306Hesman Brigette E 31116Hewagama Tilak 21706Hibbitts Charles A 21505Hill Matthew Eric 21026Hines Dean C 41313Hinkle Mary L 30104Hinson David P 10501Hirabayashi Masatoshi40204Hoette Vivian L 21921Hofstadter Mark D 41304Holler Bryan J 50809Hollingsworth Jeffery L41905Holman Matthew J 21112Hora Joseph L 31221Howe Alex 41614Howell Ellen S 21311Howell Robert R 40901

178

Howett Carly Jacqueline Amy10205Hsieh Henry H 41402Hu Renyu 40409Hudson Reggie L 21107Hue Vincent 31115Hueso Ricardo 40002Hui Man-To 41518Hurford Terry 20109Hurley Dana 41006Hutcherson Adam 21509Hyodo Ryuki 21810Imanaka Hiroshi 41618Irwin Patrick Gerard Joseph40001Jackson Brian K 50108Jacobson Robert A 10208Jakosky Bruce M 30501Jakubik Marian 21319Jedicke Robert 31225Jehin Emmanuel 41312Jennings Donald E 30005Johnson Robert E 31002Johnson Torrence V 40403Jones Lynne 31222Jorda Laurent 41309Jost Bernhard 41302Kahre Melinda A 41906Kaib Nathan A 41803Kalyaan Anusha 50707Kammer Joshua A 10204Karkoschka Erich 31003Kaspi Yohai 40408Kataria Tiffany 50407Kavelaars J J 21114Kawakita Hideyo 41515Keane James Tuttle 30709Keller Horst Uwe 50009Keller John W 21507Kelley Michael S 50607Khayat Alain 41912Killen Rosemary M 21501Kim Sang J 31114Kinser Rebeca 31001Kitazato Kohei 30713Klassen David R 2191441908Klaus Kurt K 31223Klima Rachel L 21318Knight Matthew M 50611Kohout Tomas 21213Kollmann Peter 10510Komacek Thaddeus D21902 50408Kopparla Pushkar 41611Kortenkamp Stephen J20204 30902Korycansky D G 30907Koskinen Tommi 21016Kostiuk Theodor 50202Koutroumpa Dimitra 10703Kramer Emily A 50609Kutepov Alexander 31011Lambrechts Michiel 50703DLamy Philippe L 41303Landsman Zoe A 10610Lanzano Alexander 31006Larsen Jeffrey A 30814Larson Erik J 31005Lavvas Panayotis 20508Le Beau Raymond P 31105Le Gall Alice 21007Le Maistre Sebastien 42006Lederer Susan M 41502Lee Greg 31013

Lee Seungwon 50302Lee Yuni 50503Lehner Matthew J 21116Leith Thomas 10603Lejoly Cassandra 20302Lellouch Emmanuel 10507Lemmon Mark T 40109Levasseur-Regourd A 41310Levison Harold F 30204Lewis Benjamin 2191141517Lewis Mark C 21808Leyrat Cedric 41305Li Cheng 31107Li Daohai 41201Li Jian-Yang 10304Liang Mao-Chang 21023Lightholder Jack 31226Ligier Nicolas 40507Lilly (Schunova) Eva 21406Limaye Sanjay 21704Lin Hsing-Wen 21117Linscott Ivan 10103Lisse Carey M 21005Lister Tim 30816Livengood Timothy A 41911Loeffler Mark J 50206Lora Juan M 30004Lorenz Ralph 41925Lorenzi Vania 21008Lovell Amy J 41514Lucas Michael P 21316Luhmann Janet 50502Luiz Andre Amarante10211DLustig-Yaeger Jacob 41610Luszcz-Cook Statia H 31103Lyons James 50709MacDonald Mariah G 50105Macke Robert J 20403MacKenzie Shannon 31224MacLennan Eric M 21305Mai Chuhong 41612Mainzer Amy K 30801Makarov Valeri 10706Malina Ondrej 21313Mankovich Christopher31127Marchant Jon 41316Marchi Simone 10303Marchis Franck 50101Margot Jean-Luc 50103Marshall Sean E 20409Marsset Michael 10611Martone Alexis 21707Marzari Francesco 41709Matcheva Katia 31132Matson Dennis L 41003Mayo Louis 21916McAdam Margaret 10608McCord Thomas B 21211McDonald George D 31012McFadden Lucy-Ann A21209McGouldrick Kevin 20102McGrath Melissa 40904McKay Adam 50603McKinnon William B 10106McNutt Ralph L 10509Meech Karen Jean 50704Meinke Bonnie K 20209Mellton Chad 21104Meyer Michael 40101Michaels Timothy I 21022Migliorini Alessandra 50304

Milam Stefanie N 50605Milbury Colleen 10709Mitchell Emily H 50807DMolter Edward M 31015Momary Thomas W 31119Mommert Michael 30804Montmessin Franck 41917Moore Casey A 41907Moore Jeffrey M 1000310203Moores John 10710Moorhead Althea V 30818Morate David 21321Moretto Mark J 50608Morgan Thomas H 31203Morishima Ryuji 30906Morooka Michiko W 41922Moses Julianne I 50405Moskovitz Nicholas 30810Moullet Arielle 31131Mousis Olivier 30910Mueller Beatrice E A 50610Mueller Michael 20401Mumma Michael J 41909Muntildeoz-Gutieacuterrez MarcoAntonio 50104DMusacchio Fabrizio 40501DMusiolik Grzegorz 30909Naidu Shantanu P 20408Nance Elizabeth 31104Nault Kristie A 30815Nayak Michael 20108Neish Catherine 10708Nelson Robert M 40502Nesvold Erika 41707Nesvorny David 20308Neveu Marc 10310DNixon Conor A 31014Noll Keith S 21101Novak Robert E 41910Nugent Carolyn 30101Nugent Carolyn R 21905ONeill Morgan E 40307Ohtsuki Keiji 21410Oklay Nilda 50007Olkin Catherine B 10101Opitom Cyrielle 50602DOrton Glenn S 50204Otarola Angel 31218Paddack Stephen 40201Paetzold Martin 50001Paganini Lucas 41511Pajuelo Myriam Virginia20105Palmer Eric 21317Parisi Marzia 50209DPark Ryan 21210Parker Alex Harrison 20309Parkinson Christopher D31122Pasachoff Jay M 1070721012Patterson Gerald Wesley31209Payne Matthew John 21113Peacock Sarah 40406Pendleton Yvonne J 21601Penteado Paulo F 21106Penttilauml Antti 21307Perera Viranga 2020620404Perez-Hoyos Santiago 31123Perry Mark E 41004Person Michael J 10505Philippe Sylvain 21019

Piccialli Arianna 20103Pieters Carle M 10302Pike Rosemary E 20306DPilorget Cedric 40103Pitman Karly M 50805Podolak Morris 31106Polidan Ronald S 21703Polishook David 40202Porter Simon B 10210Portyankina Ganna 41005Poston Michael 30209Poulet Francois 50004Prem Parvathy 10711Prettyman Thomas H 21309Prialnik Dina 41106Protopapa Silvia 41508Quillen Alice C 50802Radebaugh Jani 21901Rafkin Scot CR 30003Rall Jonathan 21924Ramanjooloo Yudish50601DRannou Pascal 31004Raponi Andrea 21202Rathbun Julie A 3120140505Raugh Anne C 31204Rauscher Emily 40801Raymond Carol A 10301Rehnberg Morgan 1040420205Resnick Aaron C 21015Retherford Kurt D 10508Richardson Derek C 21806Richardson James E 30808Richey Christina 40601Ries Judit Gyorgyey 21904Rimlinger Thomas 41804Rivkin Andrew S 10607Roberts James H 21207Roberts-Pierel J D 31128Rodriguez-Ford Linda A20207Roe Henry G 21018Roig Fernando Virgilio21405Rosenblatt Pascal 30208Roth Nathan 41509Rousselot Philippe 21102Ruesch Ottaviano 10311DRuprecht Jessica D 30802Russell April 21923Russell Christopher T20901 50201Ryan Eileen V 20203Ryan Erin L 30106Ryan William 30806Saito Hiroaki 30903Salmon Julien 10408Samarasinha Nalin H 41505Sanchez Juan Andres 21302Saacutenchez Paul 40208Sanchez-Lavega Agustin40003Sandor Brad J 20104Sarid Gal 30706Sayanagi Kunio M 31118Schaefer Laura 41609Schaible Micah 50804Schambeau Charles Alfred41522Schenk Paul M 20006Schinder Paul J 31007Schloerb F Peter 50002Schmidt Britney E 10308

179

Schneider Nicholas M 41916Schools Joe 42005Schroumlder Stefan 10305Schulz Rita 30911Schwamb Megan E 21109Schwieterman Edward20208 40404Sciamma-OBrien Ella 20507Scipioni Francesca 50803Scully Jennifer E C 21203Serigano Joseph 20504Sharkey Benjamin N L30807Sheets Holly A 40407Sheppard Scott S 20307Shinnaka Yoshiharu 41516Shou Yinsi 41519Showalter Mark R 10209Shupla Christine 21910Sicardy Bruno 10401Sickafoose Amanda A 10504Sidrow Evan 21025Sie Zong-Fu 21110Simmons Gary G 41101Simon Amy A 50205Sinclair James 31113Singer Kelsi N 10202Siu Ho Chit 40203Sizemore Hanna G 21205Skrutskie Michael F 40902Smith Howard T 21033Smith Mary-Ann H 41920Smith Robert J 21034Soderlund Krista M 40508Solin Otto 21408Solomonidou Anezina 30006Sonnett Sarah M 30105Spalding Christopher 50107Spencer John R 10105

Spiga Aymeric 31111Spilker Linda J 21801Spitale Joseph N 41002Springmann Alessondra41404Squire Jared 31213Sromovsky Lawrence A40004Stamper Nicholas C 21306Stansberry John A 21032Stark Glenn 31133Steckloff Jordan 41506Steffl Andrew J 41308Stern SA 10001Stevens Michael H 41915Stevenson David J 40303Stewart Glen R 21811Stickle Angela M 31214Stofan Ellen R 20201Summers Michael E 10511Sung Keeyoon 31018Sunshine Jessica 21212Svedhem Haringkan 41919Sykes Mark V 21206Sylvestre Melody 40008DTabeshian Maryam 41708Tabor-Morris Anne 21918Takahashi Yasuto 40007DTakir Driss 10602Tamayo Daniel 41204Teanby Nicholas A 20502Tegler Stephen C 21105Teiser Jens 42004Tejfel Victor G 31109Tellmann Silvia 41903Tenishev Valeriy 50309Thelen Alexander E 31126Thirouin Audrey 20301Tholen David J 41403

Thomas Cristina A 30813Throop Henry B 2100921035 21925Tinetti Giovanna 41620Tiscareno Matthew S 10407Titus Timothy N 20402Tokunaga Alan T 31220Tozzi Gian-Paolo 50307Trafton Laurence M 21002Trainer Melissa G 2050621913Traub Wesley A 50711Trilling David E 30102Trimble Christie J 10406Trowbridge Alexander J10201DTrujillo Chadwick A 21111Tsang Constantine 21705Turner Neal J 21803Turrini Diego 50705Umurhan O M 21011Urata Richard Atsuki 40106Van Laerhoven Christa L41706Verbiscer Anne J 21003Veres Peter 30803Verma Ashok Kumar 10705Vernazza Pierre 10612Vervack Jr Ronald J 10701Videen Gorden 41513Vilas Faith 10704Villanueva Geronimo Luis20701 50501Villarreal Michaela 21201Vinatier Sandrine 20501Vincent Jean-Baptiste 41307Virkki Anne 20406DVodniza Alberto Quijano30805

Volk Kathryn 20305Vrastil Jan 21403Wainscoat Richard J 30107Wakeford Hannah 50402DWalsh Kevin J 30205Wang Huiqun 41904Warner Brian D 30702Weaver Harold A 1000210207Weissman Paul R 3090540701Weryk Robert J 41525West Robert A 50208White Oliver 21006Whizin Akbar 50701DWiegert Paul 41521Wigton Nathanael 10606Williamson Hayley N 41901Wong Ian 20303Wong Michael H 40305Wong Michael L 21021Woodson Adam 41926Yanamandra-Fisher Padma A21903 31135Yang Bin 30109Ye Quan-Zhi 30817Young Cindy L 50808Young Eliot F 21010Young Leslie 10104Yu Tze Yeung Mathew 21108Yung Yuk 30401Zalucha Angela M 21024Zangari Amanda M 21001Zhang Xi 41608Zhang Zhimeng 21802Ziffer Julie 21922Zou Xiaoduan 21308Zuluaga Carlos A 21013

180

100 ndash New Horizons Plenary Session10001 ndash The Pluto System Initial Results from theExploration by New HorizonsThe Pluto system was recently explored by NASArsquos New Horizonsspacecraft which made closest approach on 14 July 2015 Plutorsquossurface is found to be remarkably diverse in landforms terrainages and albedo color and composition gradients Strongevidence is found for a water-ice crust geologically young surfaceunits ice convection wind streaks and glacial flow Plutorsquosatmosphere is found to be very extended and contains newlydiscovered trace hydrocarbons has an extensive global haze layerand a surprisingly low surface pressure of ~10 microbars Plutorsquoswide range of surface expressions and long term activity raisesfundamental questions about how small planets can have activeprocesses billions of years after their formation The geology ofPlutorsquos large moon Charonrsquos is also surprisingly diverse displayingtectonics and evidence for a heterogeneous crustal compositionthe north pole displays puzzling dark terrain No evidence for aCharon atmosphere is found Plutorsquos small satellites Hydra and Nixare small elongated objects with higher albedos than expectedSurprisingly despite much improved diameter limits no newsatellites are found We will present an overview of the NewHorizons flyby payload and results This work was supported bythe NASA New Horizons project

Author(s) SA Stern Harold Weaver Leslie Young Catherine Olkin Kimberly Ennico Jeff Moore Will Grundy Randall Gladstone Fran BagenalInstitution(s) 1 Johns Hopkins Applied Physics Laboratory 2Lowell Observatory 3 NASA Ames Research Center 4 SwRI 5SwRI 6 University of Colorado

10002 ndash New Horizons Investigations of Charon andPlutos Small MoonsDuring the flyby of the Pluto system in July 2014 the instrumentson the New Horizons spacecraft (Weaver et al 2008 Space SciRev 140 75) acquired spatially resolved measurements of Charonand Plutos small moons (Styx Nix Kerberos and Hydra) Thesunlit hemisphere of Charon was mapped in panchromatic lightwith resolutions as high as 015 kmpix using LORRI and in fourdifferent color bands (400ndash550 nm 540-700 nm 780ndash975 nm860-910 nm the latter is centered on a weak CH4 band) withresolutions as high as 14 kmpix using MVIC Composition mapsof Charon were obtained with the LEISA infrared spectral imager inthe wavelength range 125-250 microns with a spectral resolvingpower of ~250 and with spatial resolutions up to 49 kmpix Solaroccultation observations with the Alice ultraviolet spectrographand radio occultation measurements with REX were used tosearch for an atmosphere around Charon Nix was observed byLORRI in panchromatic light at 030 kmpix by MVIC in color at20 kmpix and by LEISA at 36 kmpix (the latter to bedownlinked later) Hydra was observed by LORRI in panchromaticlight at 11 kmpix in color at 46 kmpix and by LEISA at 149kmpix (the latter to be downlinked later) Limited resolvedmeasurements of Kerberos (20 kmpix panchromatic 80 kmpixcolor) and Styx (32 kmpix panchromatic 80 kmpix color) werealso obtained but have not yet been downlinked An extensiveseries of unresolved photometric measurements of Plutos smallmoons were obtained with LORRI during several monthspreceeding closest approach in mid-July which place tightconstraints on their shapes and rotational statesThe New Horizons data have revealed that Charon has surprisinglydiverse terrain with evidence of tectonics and a heterogeneouscrustal composition Nix and Hydra are highly elongated bodieswith high average albedos (suggesting water-ice dominatedsurfaces) and significant albedo and color variations over theirsurfaces We will present estimates for the densities spin periodsand physical properties of all the small satellites This work wassupported by NASAs New Horizons project

Author(s) Harold A Weaver S A Stern L A Young CB Olkin K Ennico J M Moore W B McKinnon J RSpencer W M Grundy D P Cruikshank G P Gladstone ME Summers F BagenalInstitution(s) 1 George Mason University 2 Johns HopkinsAPL 3 Lowell Observatory 4 NASA Ames Research Center 5Southwest Research Institute 6 University of Colorado 7Washington University

10003 ndash Geology of Pluto and Charon OverviewPlutorsquos surface was found to be remarkably diverse in terms of itsrange of landforms terrain ages and inferred geological processesThere is a latitudinal zonation of albedo The conspicuous brightalbedo heart-shaped feature informally named Tombaugh Regio iscomprised of several terrain types Most striking is Texas-sizedSputnik Planum which is apparently level has no observablecraters and is divided by polygons and ovoids bounded by shallowtroughs Small smooth hills are seen in some of the polygon-bounding troughs These hills could either be extruded or exposedby erosion Sputnik Planum polygonovoid formation hypothesesrange from convection to contraction but convection is currentlyfavored There is evidence of flow of plains material aroundobstacles Mountains especially those seen south of SputnikPlanum exhibit too much relief to be made of CH CO or N andthus are probably composed of H O-ice basement material Thenorth contact of Sputnik Planum abuts a scarp above which isheavily modified cratered terrain Plutorsquos large moon Charon isgenerally heavily to moderately cratered There is a mysteriousstructure in the arctic Charonrsquos surface is crossed by an extensivesystem of rift faults and graben Some regions are smoother andless cratered reminiscent of lunar maria On such a plain are largeisolated block mountains surrounded by moats At this conferencewe will present highlights of the latest observations and analysisThis work was supported by NASAs New Horizons project

Author(s) Jeffrey M Moore S A Stern H A Weaver Leslie A Young Kimberly Ennico Cathy B OlkinInstitution(s) 1 Johns Hopkins University Applied PhysicsLaboratory 2 NASA Ames Research Center 3 SouthwestResearch Institute

10004 ndash Pluto System Surface Composition ResultsThis talk will present an overview of surface compositiondiscoveries from New Horizons exploration of the Pluto systemThe emphasis will be on results that could only have been obtainedthanks to the uniquely high spatial resolution provided by aspacecraft visit The Ralph instrument is New Horizons primarytool for investigating surface compositions in the Pluto systemRalph consists of a near-infrared spectral imager sharing a 75 mmaperture telescope assembly with a color CCD camera system TheLinear Etalon Imaging Spectral Array (LEISA) component of Ralphprovides spectral coverage from 125 ndash 25 microm at a resolving power(λΔλ) of 240 Ices such as CH N CO CO C H NH andH O have uniquely diagnostic absorption bands in this wavelengthregion The Multi-spectral Visible Imaging Camera (MVIC) has 7CCD arrays of which 4 have interference filters affixed directly onthe focal plane The filters pass wavelengths ranging from 400through 975 nm sensitive to coloration by tholin-type materials aswell as a weak CH4 ice absorption band at 890 nm Both Ralphcomponents are usually operated in a scanning mode rotating thespacecraft about its Z axis to sweep Ralphs field of view across thescene such that each point in the scene is eventually imaged at eachwavelength The width of the scanned region is 09 degrees dividedinto 256 spatial pixels for LEISA and 57 degrees spanned by 5000pixels for MVIC Over the course of the summer 2015 flybynumerous Ralph observations targeted the various bodies in thePluto system As of late 2015 transmission of the data to Earthcontinues but already a number of spectacular data sets areavailable for analysis including LEISA scans of Pluto at 6 to 7kmpixel and of Charon at 3 kmpixel as well as MVIC scans ofPluto at 700 mpixel and of Charon at 5 kmpixel This work wassupported by the NASA New Horizons Project

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Author(s) William M Grundy R P Binzel J C Cook D PCruikshank C M Dalle Ore A M Earle K Ennico D EJennings C JA Howett I R Linscott A W Lunsford C BOlkin A H Parker J Wm Parker S Protopapa D C Reuter KN Singer J R Spencer S A Stern C CC Tsang A J Verbiscer H A Weaver L A YoungInstitution(s) 1 Johns Hopkins University Applied PhysicsLaboratory 2 Lowell Obs 3 MIT 4 NASA Ames ResearchCenter 5 NASA Goddard Space Flight Center 6 StanfordUniversity 7 SwRI 8 University of Maryland 9 University ofVirginia

10005 ndash New Horizons Observations of theAtmospheres of Pluto and CharonMajor goals of the New Horizons (NH) mission are to explore andcharacterize the structure and composition of Plutorsquos atmosphereand to establish whether Charon has a measurable atmosphere ofits own The primary instruments onboard NH which contribute tothese goals are the REX instrument through uplink X-band radiooccultations the Alice instrument through extreme- andfar-ultraviolet solar occultations and the LORRI panchromaticimager through high-phase-angle imaging The associateddatasets were obtained following closest approach of NH to PlutoPressure and temperature profiles of the lower atmosphere arederived from the REX data the composition and structure of theextended atmosphere are derived from the Alice data (supported byapproach observations of reflected ultraviolet sunlight) and thedistribution and properties of Plutorsquos hazes are derived from theLORRI data In this talk an overview of the early atmospherescience results will be presentedThis work was supported by NASAs New Horizons project

Author(s) G R Gladstone S A Stern H A Weaver L AYoung K A Ennico C B Olkin A F Cheng T KGreathouse D P Hinson J A Kammer I R Linscott A HParker J Wm Parker K D Retherford E Schindhelm K NSinger A J Steffl D F Strobel M E Summers C C CTsang G L Tyler M H Versteeg W W Woods NCunningham W CurdtInstitution(s) 1 George Mason University 2 Max PlanckInstitute for Solar System Research 3 NASA Ames ResearchCenter 4 Nebraska Wesleyan University 5 SETI Institute 6Southwest Research Inst 7 The Johns Hopkins University 8 TheJohns Hopkins University Applied Physics Laboratory

10006 ndash Solar wind interaction with Plutorsquos escapingatmosphereNASArsquos New Horizons spacecraft carries two instruments SWAPand PEPSSI that measure low and high energy particlesrespectively These particle instruments have been measuring theconditions in the solar wind for most of the trajectory from Earth toPluto The Venetia Burney Student Dust Counter measuredimpacts from micron-sixed dust particles These particleinstruments also made observations during the flyby of Pluto onJuly 14 2015 We report on New Horizons measurements of theinteraction of the solar wind interaction with Plutorsquos extendedatmosphere and discuss comparisons with theoretical expectations

Author(s) Fran Bagenal S A Stern H A Weaver L AYoung K Ennico C Olkin D J McComas R L McNutt MHoranyi H A Elliott M E Hill E Zernstein P Kollman S MKrimigis C M Lisse D F Strobel J SzalAy M PiquetteInstitution(s) 1 JHU-APL 2 NASA Ames Research Center 3Southwest Research Institute 4 Southwest Research Institute 5The Johns Hopkins University 6 Univ of Colorado

101 ndash Pluto System I--New HorizonsHeadliner10101 ndash Color Variations on Pluto Charon amp AmongPlutorsquos Small SatellitesThis summerrsquos flyby of NASArsquos New Horizons spacecraft past Pluto

provided the first high spatial resolution imaging of the systemUsing the Ralph instrument (Reuter et al 2008 Space Sci Rev140 129) color images were obtained in 3 broadband filters andone narrow band filter blue (400 ndash 550 nm) red (540-700 nm)NIR (780 ndash 975 nm) and methane (860 ndash 910 nm) These datarevealed details about Plutorsquos variegated surface including distinctcolor boundaries in two halves of the region informally namedTombaugh Regio and intriguing color variations in Plutorsquos northpole This talk will discuss the color variations on Pluto CharonNix and Hydra Color observations of Kerberos and Styx weretaken but will not be downlinked in time for inclusion in this talkThis work was supported by NASArsquos New Horizons project

Author(s) Catherine B Olkin D C Reuter S A Stern CJ A Howett A H Parker K Ennico K N Singer W MGrundy H A Weaver L A Young R P Binzel M W Buie J C Cook D P Cruikshank C M Dalle Ore A M Earle DE Jennings I R Linscott A W Lunsford J Wm Parker SProtopapa J R Spencer CCC Tsang A J VerbiscerInstitution(s) 1 Johns Hopkins University Applied PhysicsLaboratory 2 Lowell Observatory 3 MIT 4 NASA AmesResearch Center 5 NASA Goddard Space Flight Center 6Stanford University 7 SWRI 8 University of Maryland 9University of Virginia

10102 ndash Pluto Distribution of ices and coloringagents from New Horizons LEISA observationsPluto was observed at high spatial resolution (maximum ~3kmpx) by the New Horizons LEISA imaging spectrometer LEISAis a component of the Ralph instrument (Reuter DC Stern SAScherrer J et al 2008 Space Sci Rev 140 129) and affords aspectral resolving power of 240 in the wavelength range 125-25microm and 560 in the range 21-225 microm Spatially resolved spectrawith LEISA are used to map the distributions of the known ices onPluto (N CH CO) and to search for other surface componentsThe spatial distribution of volatile ices is compared with thedistribution of the coloring agent(s) on Plutos surface Thecorrelation of ice abundance and the degree of color (ranging fromyellow to orange to dark red) is consistent with the presence oftholins which are refractory organic solids of complex structureand high molecular weight with colors consistent with thoseobserved on Pluto Tholins are readily synthesized in the laboratoryby energetic processing of mixtures of the ices (N CH CO)known on Plutos surface We present results returned from thespacecraft to date obtained from the analysis of the high spatialresolution dataset obtained near the time of closest approach to theplanet Supported by NASArsquos New Horizons project

Author(s) Dale P Cruikshank William M Grundy S AlanStern Catherine B Olkin Jason C Cook Cristina M DalleOre Richard P Binzel Alissa M Earle Kimberly Ennico Donald E Jennings Carly JA Howett Ivan R Linscott AllenW Lunsford Alex H Parker Joel W Parker SilviaProtopapa Dennis C Reuter Kelsi N Singer John RSpencer Constantine C C Tsang Anne J Verbiscer HaroldA Weaver Leslie A YoungInstitution(s) 1 Applied Phys Lab 2 Lowell Observatory 3MIT 4 NASA Ames Research Center 5 NASA Goddard SpaceFlight Center 6 SETI Institute 7 Stanford Univ 8 SWRI 9Univ Maryland 10 Univ Virginia

10103 ndash First Results from The New Horizons RadioScience Experiment Measurements of PlutosAtmospheric Structure Surface Pressure andMicrowave Brightness TemperatureThe Radio Science Experiment (REX) on board the New Horizonsspacecraft measured key characteristics of Pluto and Charonduring the July 14 2015 flyby The REX flight instrument isintegrated into the NH X-band radio transceiver and provides highprecision narrow band recording of powerful uplink transmissionsfrom Earth stations as well as a record of broadband radiometricpower This presentation reviews the performance and initialresults of the radio occultation of Pluto the radiometrictemperature profiles and gravity measurements during the

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encounter REX received two pair of 20-kW uplink signals onepair per polarization transmitted from the DSN at 42- cmwavelength during a diametric radio occultation of Pluto The REXrecording of the uplinks affords a precise measurement of thesurface pressure the temperature structure of the loweratmosphere and the surface radius of Pluto The ingress portion ofone polarization was played back from the spacecraft in July whilethe egress portion of the same polarization was played back inAugust Both ingress and egress segments of the occultation havebeen processed to obtain the pressure and temperature structure ofPlutorsquos atmosphere In addition REX measured the thermalemission from Pluto at 42- cm wavelength during two linear scansacross the disk at close range when both the dayside and the nightside were visible Both scans extend from limb to limb with aresolution of one-tenth Plutorsquos disk and temperature resolution of01 K A third radiometric scan was obtained during the dark sidetransit of the occultation This work was supported by NASArsquos NewHorizons project

Author(s) Ivan Linscott Alan Stern Hal Weaver LeslieYoung Cathy Olkin Kim EnnicoInstitution(s) 1 JHUAPL 2 NASA AMES 3 StanfordUniversity 4 SWRI

10104 ndash Volatile Transport Implications from the NewHorizons Flyby of PlutoThe New Horizons flyby of Pluto has revealed a striking range ofterrains from the very bright region informally named SputnikPlanum to very dark regions such as the informally namedCthulhu Regio Such a variety was beyond the scope of recentmodels of Plutos seasonal volatile cycle (Young 2013 ApJL 766L22 Hansen Paige and Young 2015 Icarus 246 183) whichassumed globally uniform substrate albedos The Exchange withPressure Plateau (EPP) class of models in Young (2013) and thefavored runs from Hansen et al (2015) had long periods ofexchange of volatiles between northern and southern hemispheresIn these models the equators were largely devoid of volatiles eventhough the equatorial latitudes received less insolation than thepoles over a Pluto year they were never the coldest place on the icyworld New models that include a variety of substrate albedos caninvestigate questions such as whether Sputnik Planum has analbedo that is high enough to act as a local cold trap for much ofPlutos year We will present the implications of this and otherassumption-busting revelations from the New Horizons flyby Thiswork was supported by NASArsquos New Horizons project

Author(s) Leslie Young William M Grundy RIchard PBinzel Alissa M Earle Ivan R Linscott David P Hinson Amanda M Zangari William B McKinnon S Alan Stern Harold A Weaver Catherine B Olkin Kimberly Ennico GRandall Gladstone Michael E Summers Jeffrey M Moore John R SpencerInstitution(s) 1 George Mason University 2 Johns HopkinsUniversity Applied Physics Laboratory 3 Lowell Observatory 4MIT 5 NASA Ames Research Center 6 Southwest Research Inst7 Stanford University 8 Washington Univ in St Louis

10105 ndash Small Satellites and Dust in the Pluto SystemUpper Limits and ImplicationsTo help ensure safe passage of the New Horizons (NH) spacecraftas it flew through the Pluto system we took a series of deep imageswith the Long Range Reconnaissance Imager (LORRI) to searchfor previously undetected satellites or rings We obtained a total of1100 10-second exposures spread over 20 epochs between May 11and July 1 2015 HST observations had previously set an upperlimit to the brightness of undetected moons of about half Styxsbrightness (ie a diameter of ~5 km for an a Charon-like albedo of038) The final NH observations in early July could have detectedobjects down to ~15 km in diameter in the Charon - Hydra regionand ~2 km between Charons orbit and ~5000 km above Plutossurface Despite the sensitivity of the searches no additionalmoons were found The lower limit on the brightness ratio betweenStyx and any undiscovered fainter satellites ~20 is comparable tothe brightness ratio between Nix and Kerberos (~16) and a

power-law satellite size distribution analogous to that seen in theSaturn system cannot be ruled out Implications of the satellitesize distribution for the origin of the satellite system will bediscussed The data also place an upper limit of ~1 x 10 on the IFof any dust rings in the vicinity of the known small satellites afactor of several improvement over previous HST limits This workwas supported by NASArsquos New Horizons project

Author(s) John R Spencer Mark R Showalter S AlanStern Marina Brozovic Marc W Buie Douglas P Hamilton Robert A Jacobson David E Kaufmann Tod R Lauer Alex HParker Simon B Porter Henry B Throop Anne J Verbiscer Harold A Weaver Leslie A Young Kimberly Ennico CatherineB OlkinInstitution(s) 1 Applied Physics Laboratory 2 Jet PropulsionLaboratory 3 NASA Ames Research Center 4 National OpticalAstronomy Observatory 5 Planetary Science Institute 6 SETIInstitute 7 Southwest Research Institute 8 University ofMaryland 9 University of Virginia

10106 ndash What We Know Now Synthesis forUnderstanding the Origin of the Pluto SystemThe July 2015 New Horizons flyby has removed a long-standingobstacle to understanding the cosmogony of the Pluto-Charonsystem the uncertain radius of Pluto Combined with preciseastrometric fits to the barycenter of the Pluto-Charon binary fromHST observations of the more distant small satellites (Brozovic etal Icarus 246 317ndash329 2015) the densities of both Pluto andCharon are now known At the 10 level these densities are rathersimilar as opposed to the more divergent density estimates of yearspast in which Charon was thought to be substantially icier In thecontext of a ldquogiant impactrdquo origin a rock-rich Charon implies thatthe precursor impacting bodies were at most only partiallydifferentiated mdash possessing relatively thin ice shells (CanupAstron J 141 35 2011) This suggests some combination ofrelatively slow andor late accretion in the ancestral Kuiper beltNew Horizons has also shown that Nix and Hydra possess highalbedos consistent with ice-dominated compositions Suchcompositions are consistent with a giant impact origin in which oneor both precursor impacting bodies were partially differentiated sothat the small satellites ultimately formed from material ejectedfrom ice-dominated surface layers (Peale and Canup Treatise onGeophysics 2 Ed chapter 1017 2015) We examine whetherPluto and Charon could actually possess the same bulk rockiceratio and whether this would allow for an alternate non-giant-impact origin for the Pluto systemThis work was supported by NASAs New Horizons project

Author(s) William B McKinnon S A Stern H AWeaver J R Spencer F Nimmo C M Lisse O MUmurhan J M Moore M W Buie S B Porter C B Olkin L A Young K EnnicoInstitution(s) 1 APL 2 NASA Ames 3 SETI 4 SwRI 5 UCSC6 Washington Univ

102 ndash Pluto System II--Pluto Surface andSatellites10201D ndash Vigorous Convection Underlies PlutorsquosSurface ActivityAgainst many expectations New Horizonsrsquo images of the surface ofPluto and Charon show seemingly young surfaces On Plutoimages of an equatorial region south of the Tombaugh Regio reveala mountain range with peaks jutting as high as 3500 meters Thelow concentration of craters for these mountains suggests an age of100 million years indicating that Pluto is geologically active Otherevidence for geologic activity includes a fault cross-cutting ridgessmooth lightly cratered plains with flow fronts and a pair ofapparent stratovolcanoes Charon similarly possesses very fewcraters and a spectacular system of troughs Both observationssuggest the possible presence of active cryogeysers andcryovolcanoes The underlying cause of modern tectonic andvolcanic activity on any object is likely a vigorous mantle

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convection regime We are thus led to consider what determinesplanetary vigor While Pluto and Charon seem to be quite activeCeres and the much larger Callisto seem to lack modern endogenicactivity even though all of these bodies are likely to possess waterice mantlesWe coupled a parameterized convection model with a temperaturedependent rheology for pure water ice deducing a barely criticalRayleigh number of ~1600 for Plutorsquos mantle and lt1000 forCharon suggesting that a water ice mantle alone may beinsufficient to support vigorous convection in these bodiesHowever in the outer solar system other volatiles may havecondensed Ammonium hydrate has been reported on the surfaceof Charon At temperatures above the eutectic (176 K) Durham etal (1993) showed that NH lowers the viscosity of water ice by 4orders of magnitude Our model indicates that with NH themean temperature of the mantle of Pluto is at the eutectic and itsRa ~ 10^4 The presence of NH dramatically increases the vigor ofconvection for the two bodies and suggests that ammonia-waterslurries are the basis for Plutorsquos volcanism We propose that thepresence or absence of active mantle convection may offer auniversal criterion for endogenic planetary vigor

Author(s) Alexander J Trowbridge Henry Jay Melosh Andy M FreedInstitution(s) 1 Purdue University

10202 ndash Craters on Pluto and Charon Characteristicsand Impactor PopulationAlthough both Pluto and Charon have a surprising number ofyoung-looking surfaces there are still plenty of craters for impact-phenomenon enthusiasts We will present size morphologyejecta and albedo pattern statistics in addition to correlations withcolorcomposition where possible We use images and topographyfrom the Long Range Reconnaissance Imager (LORRI Cheng etal 2008 SSR 140 189-215) and data from the Ralph (Reuter etal 2008 SSR 140 129-154) colorcomposition instrumentsImpactor sizes will be estimated from relevant scaling laws for coldwater ice (see details in Singer and Stern 2015 ApJL 808 L50)For Pluto an image strip at 125 m px includes some crateredterrains and much of the encounter hemisphere (the anti-Charonhemisphere) will be covered at ~400 m px The ~smallest cratersobservable at these pixel scales (using a 5 pixel limit) would be~063 km and ~2 km in diameter respectively with impactordiameters estimated at ~50 m and ~200 m However it is likelythat degradation processes may obscure small craters thus thislower observation limit will depend on terrain type Additionallylighting and observation geometries vary across the disk whichmay make crater detection difficult in some areas All of theilluminated portions of Pluto (during its 64 day rotation period)were imaged at ~20 km px or better during the encounter Thehighest resolution images of Pluto (at ~80 m px ) occur in anarrow strip and are not scheduled for downlink before the DPSThe highest resolution Charon coverage (a strip at ~160 m px ) abroader swath at 400 m px and the entire encounter hemisphere(the sub-Pluto hemisphere) at ~890 m px may yield craters assmall as 08 2 and 45 km in diameter respectively The inferredimpactor sizes for these craters would be ~50 m 160 m and 440 mAlthough the dataset is limited we will discuss what constraintscan be put on the impactor population This work was supported bythe NASA New Horizons project

Author(s) Kelsi N Singer Paul M Schenk Stuart JRobbins Veronica J Bray William B McKinnon Jeffrey MMoore John R Spencer S A Stern W M Grundy Carly JAHowett Cristina M Dalle Ore Ross Beyer Alex H Parker Simon B Porter Amanda M Zangari Leslie A Young Cathy BOlkin Kimberly EnnicoInstitution(s) 1 Lowell Observatory 2 Lunar and PlanetaryInstitute 3 Lunar and Planetary Laboratory University ofArizona 4 NASA Ames Research Institute 5 SETI Institute 6Southwest Research Institute 7 Washington University in StLouis

10203 ndash Processes Modifying Cratered Terrains on

PlutoThe July encounter with Pluto by the New Horizons spacecraftpermitted imaging of its cratered terrains with scales as high as~100 mpixel and in stereo In the initial download of imagesacquired at 22 kmpixel widely distributed impact craters up to260 km diameter are seen in the near-encounter hemisphereMany of the craters appear to be significantly degraded or infilledSome craters appear partially destroyed perhaps by erosion such asassociated with the retreat of scarps Bright ice-rich depositshighlight some crater rims andor floors While the crateredterrains identified in the initial downloaded images are generallyseen on high-to-intermediate albedo surfaces the dark equatorialterrain informally known as Cthulhu Regio is also densely crateredWe will explore the range of possible processes that might haveoperated (or still be operating) to modify the landscape from that ofan ancient pristinely cratered state to the present terrains revealedin New Horizons images The sequence intensity and type ofprocesses that have modified ancient landscapes are among otherthings the record of climate and volatile evolution throughoutmuch of the Plutorsquos existence The deciphering of this record will bediscussed This work was supported by NASAs New Horizonsproject

Author(s) Jeffrey M Moore Alan D Howard Oliver LWhite Orkan M Umurhan Paul M Schenk Ross A Beyer William B McKinnon Kelsi N Singer John Spencer S AStern H A Weaver Leslie A Young Kimberly Ennico CathyB OlkinInstitution(s) 1 Johns Hopkins University Applied PhysicsLaboratory 2 Lunar and Planetary Institute 3 NASA AmesResearch Center 4 Southwest Research Institute 5 University ofVirginia 6 Washington University

10204 ndash In Charons Shadow Analysis of the UV SolarOccultation from New HorizonsObservations of Charon Plutos largest moon have so far yieldedno evidence for a substantial atmosphere However during theflyby of New Horizons through the Pluto-Charon system the Aliceultraviolet spectrograph successfully acquired the most sensitivemeasurements to date during an occultation of the sun as NewHorizons passed through Charons shadow These observationsinclude wavelength coverage in the extreme- and far-ultraviolet(EUV and FUV) from 52 nm to 187 nm We will present theseresults from Alice and discuss their implications for an atmosphereon CharonThis work was supported by NASAs New Horizons project

Author(s) Joshua A Kammer S A Stern H A Weaver L A Young K A Ennico C B Olkin G R Gladstone M ESummers T K Greathouse K D Retherford M H Versteeg J W Parker A J Steffl E Schindhelm D F Strobel I RLinscott D P Hinson G L Tyler W W WoodsInstitution(s) 1 George Mason University 2 JHU AppliedPhysics Laboratory 3 Johns Hopkins University 4 NASA AmesResearch Center 5 Southwest Research Institute 6 SouthwestResearch Institute 7 Stanford University

10205 ndash Charonrsquos Color A view from New HorizonRalphMultispectral Visible Imaging CamerThe Multispectral Visible Imaging Camera (MVIC Reuter et al2008) is part of Ralph an instrument on NASArsquos New Horizonsspacecraft MVIC is the color lsquoeyesrsquo of New Horizons observingobjects using four bands from blue to infrared wavelengthsMVICrsquos images of Charon show it to be an intriguing place a far cryfrom the grey heavily cratered world once postulated RatherCharon is observed to have large surface areas free of craters and anorthern polar region that is much redder than its surroundingsThis talk will describe these initial results in more detail forexample is Charonrsquos redder pole caused by molecules that haveescaped Plutorsquos atmosphere only to be captured and frozen ontothe surface of Charonrsquos cold polar region where they haveundergone photolysis Charonrsquos global geological color variationswill also be discussed to put these results into their wider contextThis work was supported by NASArsquos New Horizons project

33

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Author(s) Carly Jacqueline Amy Howett Cathy B Olkin William M Grundy Alex H Parker Kimberly Ennico Sol AlanStern Richard P Binzel Jason C Cook Dale P Cruikshank Cristina M Dalle Ore Alissa Earle Don E Jennings IvanLinscott Allen W Lunsford Joel Wm Parker SilviaProtopapa Dennis C Reuter Kelsi N Singer John R Spencer Con CC Tsang Anne J Verbiscer Hal A Weaver Leslie AYoungInstitution(s) 1 Applied Physics Laboratory 2 LowellObservatory 3 Massachusetts Institute of Technology 4 NASAAmes 5 NASA Goddard Space Flight Center 6 SouthwestResearch Institute 7 Stanford University 8 University ofMaryland 9 University of Virigina

10206 ndash The Chasmata and Montes of CharonThe New Horizons spacecraft made the first-ever high-resolutionobservations of Plutos largest moon Charon on 14 July 2015Those observations returned views of complicated topography onthis icy world in the outer solar system Charon posseses a series ofchasmata and fossae that appear to form an organized tectonic beltthat spans across the disk of the Pluto-facing hemisphere and mayextend beyond In addition there are enigmatic isolatedmountains visible that are surrounded by depressions These inturn are surrounded by a relatively smooth plain broken byoccaisional rilles that stretches from these montes northward up tothe chasmata region We will discuss these features and more Thiswork was supported by NASAs New Horizons project

Author(s) Ross A Beyer Olivier Barnouin KimberlyEnnico Jeff Moore Francis Nimmo Cathy B Olkin PaulSchenk John Spencer S Alan Stern Hal A Weaver Leslie AYoungInstitution(s) 1 Applied Physics Laboratory Johns HopkinsUniversity 2 Lunar and Planetary Institute 3 NASA AmesResearch Center 4 SETI Institute 5 Southwest Research Institute6 University of California Santa Cruz

10207 ndash Investigating Surface Features on Nix andHydraThe LORRI (Cheng et al 2008Space Sci Rev 140 189) and MVIC(Reuter et al 2008Space Sci Rev 140 129) imagers on the NewHorizons (NH) spacecraft obtained spatially resolvedmeasurements of Nix and Hydra two of Plutos four small moonsNix was observed by LORRI in panchromatic light (350-850 nm) atresolutions up to 030 kmpix and by MVIC in color (400ndash550nm 540-700 nm 780ndash975 nm 860-910 nm the latter is centeredon a weak CH4 band) at resolutions up to 20 kmpix Hydra wasobserved by LORRI in panchromatic light at 11 kmpix and byMVIC in color at 46 kmpix The lossless versions of the imageswhich we will employ in our analysis are scheduled for downlink inSeptember and October 2015 After image deconvolutions whichtypically double the spatial resolution the NH images providehundreds to thousands of pixels across the surfaces of Nix andHydra We will present results on our searches for craterslineaments and other features on the surfaces of Nix and HydraWe will also present results on any correlations betweenmorphological features and color and albedo variations on thesurface This work was supported by NASAs New Horizons project

Author(s) Harold A Weaver O S Barnouin A F Cheng C M Ernst T R Lauer S A Stern C B Olkin K Ennico L A YoungInstitution(s) 1 Johns Hopkins APL 2 NASA Ames ResearchCenter 3 National Optical Astronomy Observatories 4 SouthwestResearch Institute

10208 ndash The Orbits and Masses of Plutos Satellitesafter New HorizonsBrozović et al (2015 Icarus 246 317) reported on Plutos mass andthe masses and numerically integrated orbits of Plutos satellitesCharon Nix Hydra Kerberos and Styx These were determinedvia a fit to an extensive set of astrometric mutual event and stellaroccultation observations over the time interval April 1965 to July2012 The data set contained the Hubble Space Telescope (HST)

observations of Charon relative to Pluto that were corrected for thePluto center-of-figure center-of-light offset due to the Pluto albedovariations (Buie et al 2012 AJ 144 15) Also included were all ofthe available HST observations of Nix Hydra Kerberos and StyxFor the New Horizons encounter with the Pluto system the initialsatellite ephemerides (PLU043) and the initial planet and satellitemasses were taken from the Brozović et al analysis During theNew Horizons approach the ephemerides and masses wereperiodically updated along with the spacecraft trajectory by the NewHorizons navigation team using imaging of the planet and satellitesagainst the stellar background In this work we report on ourpost-flyby analysis of the masses and satellite orbits derived from acombination of the original PLU043 data set the New Horizionsimaging data and HST observations acquired after 2012

Author(s) Robert A Jacobson Marina Brozovic MarcBuie Simon Porter Mark Showalter John Spencer S AlanStern Harold Weaver Leslie Young Kimberly Ennico CathyOlkinInstitution(s) 1 Johns Hopkins APL 2 JPL 3 NASA AmesResearch Center 4 SETI Institute 5 Southwest Research Institute

10209 ndash Orbital and Rotational Dynamics of PlutosSmall MoonsFour small moons Styx Nix Kerberos and Hydra orbit the centralbinary planet comprising Pluto and Charon Showalter andHamilton (Nature 522 45-49 2015) analyzed Hubble SpaceTelescope (HST) data from 2010-2012 to explore some of thedynamical consequences of orbiting a binary planet They notedevidence for a chaotic rotation of Nix and Hydra and identified apossible three-body resonance between Styx Nix and Hydra Werevisit the dynamics of the outer moons based on the latest datafrom the New Horizons flyby As the spacecraft approached Plutothe LORRI camera regularly imaged the moons over a period of~100 days This data set will make it possible to derive light curvesand rotation rates unambiguously something that has not beenpossible from the sparsely sampled HST data It also extends thetime baseline of the orbit determinations by several yearsproviding a more precise test of the proposed orbital resonancesWe will discuss the latest measurements and their dynamicalimplications for the evolution of the Pluto system This work wassupported by NASAs New Horizons project

Author(s) Mark R Showalter John R Spencer Simon BPorter Douglas P Hamilton Richard P Binzel S Alan Stern Harold A Weaver Cathy B Olkin Leslie A Young KimberlyEnnicoInstitution(s) 1 Applied Physics Lab 2 MIT 3 NASA AmesResearch Center 4 SETI Institute 5 Southwest Research Institute6 University of Maryland

10210 ndash Shapes and Poles of the Small Satellites ofPlutoPluto-Charon is a binary dwarf planet surrounded by four muchsmaller satellites Styx Nix Kerberos and Hydra (in order ofincreasing distance from the barycenter) These satellites werediscovered with the Hubble Space Telescope which also showedthat their orbits are nearly circular around the system barycenterand coplanar to the central binary NASAs New Horizonsspacecraft flew through the Pluto system on July 14 2015 andobtained the first resolved images of all four small satellites Wewill present initial models for the shapes and densities of the smallsatellites determined from both those resolved images and earlierunresolved images as well as measurements of the rotational polesof small satellites at the time of the Pluto encounter This work wassupported by the NASA New Horizons Project

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6

Author(s) Simon B Porter Mark R Showalter John RSpencer H A Weaver Richard P Binzel Douglas P Hamilton S A Stern Catherine B Olkin Leslie A Young KimberlyEnnicoInstitution(s) 1 Johns Hopkins University Applied PhysicsLaboratory 2 Massachusetts Institute of Technology 3 NASAAmes Research Center 4 SETI Institute 5 Southwest ResearchInstitute 6 University of Maryland

10211D ndash Stability of coorbital objects around thePluto-Charon binaryThe Pluto-Charon binary system is dynamical interesting with itsunusual retinue of four small moons The system is relatively fullwith few remaining stable locations for additional moons onuninclined circular orbits most of these are Trojan(TadpoleHorseshoe) orbits (Pires et al 2011 Porter and Stern2015)In this work we study the coorbital region of each moon with longtime integrations taking into account the gravitational effects of thesatellites Charon Styx Nix Kerberos and Hydra We numericallysimulate a sample of 10000 test particles initially located randomlyaround each moons orbit All test particles start on nearly circularand uninclined orbits and are followed for 5000 years The resultsof our numerical simulations show stable coorbital objects ndash bothTadpoles and Horseshoes ndash for each of the small moonsHorseshoe orbits are most common at all moons although Hydraalso has a sizeable population of Tadpole orbits We also findinteresting cases where the orbits switch from L Tadpoles toHorseshoes and even to L Tadpoles These transitioning orbitscomprise less than 1 of coorbital objects at all moons and aremost common at Styx We have also tested two different models forthe system i) Pluto and Charon as independent bodies ii) A singlecentral body with the combined mass of Pluto-Charon and aneffective J coefficient Preliminary results show only minordifferences between the two models indicating that the binary doesnot have a strong effect on coorbital motion We have alsoinvestigated eccentric and inclined orbits and will report on ourfindings

Author(s) Andre Amarante Luiz Douglas P HamiltonInstitution(s) 1 University of Maryland

103 ndash Ceres Jubilee and Vested Interests10301 ndash Interior Evolution of Ceres Revealed by DawnDawnrsquos exploration of Ceres has revealed its geophysicalcharacteristics informing the processes that have shaped it Dawnhas determined the average diameter of Ceres to be 940 kmsmaller than the previously estimated 975 km [1] This implies adensity of 2160 kgm indicating that Ceres is less differentiatedthan predicted [2] The low-degree gravity field is consistent withthe body being in hydrostatic equilibrium and the magnitude of Jimplies some central condensation Ceresrsquo entire surface iscratered implying the lack of a thick (10rsquos of km) water ice layer atthe surface Variability in Ceresrsquo crater morphology indicates thatthe near-surface layer has variable strength and rheology likelydue to heterogeneity in the near-surface mixture of rock ice andsalt The lack of a number of expected large impact basins on Cerescan be interpreted to be the result of viscous relaxation resurfacingor a combination of both These data provide insights into Ceresrsquothermal evolution and mechanical properties which appear to beunique to this warm icy body[1] Thomas P C et al Differentiation of the asteroid Ceres asrevealed by its shape Nature 437 224ndash226 2005 [2] McCord etal Ceres Its Origin Evolution and Structure and Dawnrsquos PotentialContribution Space Sci RevDOI 101007s11214-010-9729-9 2011

Author(s) Carol A Raymond Ryan S Park Alex SKonopliv Michael T Bland Simone Marchi Julie C Castillo-Rogez Thomas B McCord Ralf Jaumann Christopher TRussell Thomas H PrettymanInstitution(s) 1 Bear Fight Institute 2 DLR 3 IGPPUCLA 4Jet Propulsion Laboratory California Institute of Technology 5Planetary Science Institute 6 SwRI 7 USGS Astrogeology ScienceCenter

10302 ndash Dawn at Ceres reveals an ammoniatedsurfaceThe Visible and Infrared Mapping Spectrometer (VIR) on board theDawn spacecraft has observed Ceresrsquo surface and acquired spectra(05 to 5 microm) since January 2015 Here we report the average Ceresspectrum including the important spectral range (26-29 microm)previously precluded from (telescopic) measurements due totelluric atmospheric absorptions The VIR data confirm that thesurface is very dark with an average albedo of 0090 plusmn0006 at 055microm consistent with Hubble Space Telescope data (Li et al Icarus2006) and contains no prominent absorption features in the visibleand near-Infrared at wavelengths less than 25 microm Ceresrsquo averagespectrum however is characterized by a prominent diagnosticabsorption band at 27 microm along with weaker absorption bandsobserved between 305-31 33-34 and 39-4 microm We modeled thenew VIR spectra of Ceres with various ices meteorites silicatescarbonates and hydrates using Hapke theory Results of thespectral modeling indicate that extensive water ice is not present inspectra representing the typical surface acquired to date atrelatively low spatial resolution (lt11 kmpixel) The best fit isobtained with a mixture of ammoniated phyllosilicates mixed withother clays Mg-carbonates serpentine and a strongly absorbingmaterial such as magnetite (De Sanctis et al Nature 2015 inreview) The presence of ammonia-bearing materials in the crustacross much of the surface has implications for the origin of Ceresand its internal structure and evolution At the time of thispresentation the Dawn spacecraft will have also completed its highaltitude mapping orbit to look for anticipated small-scalemineralogy variations across this remarkable dwarf planetAcknowledgements VIR is funded by the Italian SpaceAgencyndashASI and was developed under the leadership of INAFRome-Italy The instrument was built by Selex-Galileo Florence-Italy The analyses are supported by ASI NASA and the GermanSpace Agency Enabling contributions from the Dawn InstrumentOperations and Science Teams are gratefully acknowledged

Author(s) Carle M Pieters Maria Cristina De Sanctis Eleonora Ammannito Andrea Raponi Jean-Philippe Combe Thomas B McCord Harry McSween Lucy A McFadden Simone Marchi Fabrizio Capaccioni Maria Teresa Capria Giacomo Carrozzo Mauro Ciarniello Andrea Longobardo Sergio Fonte Michelangelo Formisano Alessandro Frigeri Marco Giardino Gianfranco Magni Enersto Palomba FedericoTosi Diego Turrini Francesca Zambon Ralf Jaumann William Feldman Thomas Prettyman Michael Toplis Carol ARaymond Christopher T RussellInstitution(s) 1 Bear Fight Institute 2 Brown Univ 3 DLR 4IAPS INAF 5 JPLCalTech 6 NASA Goddard 7 ObservatoireMidi Pyreacuteneacutees 8 PSI 9 UCLA 10 Univ Tenn

10303 ndash The Origin of Dwarf Planet CeresConstrained by DawnThe Dawn spacecraft has acquired important clues regarding theorigin of dwarf planet Ceres The surface composition ischaracterized by a prominent absorption band at 27 micron that isbest explained by the presence of ammoniated phyllosilicates (DeSanctis et al 2015) while the average density indicates a bulk watercontent of 30-40 The occurrence of widespread smooth terrainsmarked by a flat topography and few superposed craters associatedwith a large 290-km crater is best explained by the present of lowviscosity material mobilized by the impact energy (Marchi 2015)Such low viscosity material is compatible with an ice-rich outershell whose melting temperature is reduced by the presence of saltsandor ammonia hydrates Such inferred internal structure couldalso explain the lack of impact structures larger than about 400 km

5 45 1 2 6

5 5 53

45

2

1 1

3

2

4 44 7 6

4 1 23 5

2 44 4 1

1 10 64 4 4

4 4 44 4 4

4 4 44 4 4 3

8 8 75 9

7

which may have relaxed leaving no obvious signatures in imagingdataThe presence of ammoniated phyllosilicates points toward thepresence of ammonia available in Ceres makeup Ammonia isrelatively rare among meteorites due to its high volatility at typicalmain belt temperatures thus indicating a potential contribution ofmaterial from the colder outer solar systemTwo main scenarios emerge Either Ceres formed in the trans-neptunian disk and subsequently was captured in the main belt orit formed close to its current position with a late addition ofmaterial drifting from the outer solar system The two scenariosimply rather different collisional evolution therefore Cerescratering record can potentially help to discriminate the more likelyevolution As craters are susceptible to degradation due to internalheat flow terrain properties and superposed cratering here we willevaluate the evidence for and against these formation scenarios bytaking into account the latest digital terrain models and gravity dataacquired by DawnDe Sanctis et al submitted July 2015Marchi S IAU General Assembly August 2015

Author(s) Simone Marchi Cristina De Sanctis DavidOBrien Eleonora Ammannito Julie Castillo-Rogez RalfJaumann Paul Schenk Carol Raymond Christopher Russell Ryan ParkInstitution(s) 1 DLR 2 INAF 3 JPL 4 LPI 5 PSI 6Southwest Research Institute 7 UCLA

10304 ndash Photometric Properties of Ceres and theOccator Bright SpotsDawn discovered several extremely bright spots on Ceres the mostprominent of which is located inside the Occator crater that is atleast 4-5 times brighter than the average Ceres Interestingly thesebright spots are located in relatively young craters that are at thelongitudes corresponding to the maximum water vapor observed bythe Herschel Space Observatory suggesting possible correlationwith water sublimation on Ceres We used the multi-color imagingdata collected by the Dawn Framing Camera to analyze the globalphotometric properties of Ceres and the bright spots especiallythose located inside the Occator crater Our objectives are todetermine the albedo and other light scattering properties of thebright spots on Ceres in the visible wavelengths in order tocharacterize their physical properties and find clues about theircomposition and possible formation mechanisms and thecorrelation with water sublimation The overall geometric albedo ofCeresrsquo global surface is 009-010 consistent with previous studiesThe Hapke roughness parameter is about 20deg close to many otherasteroids rather than 44deg as reported earlier Correspondingly thephase function of Ceres is less backscattering than previouslymodeled In contrast the geometric albedo of the bright spotsinside the Occator crater is 04-05 and the single scattering albedois 07-08 brighter than Vestarsquos global albedo but much darkerthan many icy satellites in the outer solar system The Hapkeroughness of the bright spots is much higher than Ceres averagesuggesting relatively loose deposit of materials rather than morecoherent or tightly packed materials The phase function of brightspots material is relatively more forward scattering than averageCeres possibly correlated to stronger multiple scattering due tohigh albedo resulting from more transparent materials The highestresolution images as of late-August 2015 show fine structureswithin the Occator bright spots We will also report the results fromthe albedo distribution within the bright spots

Author(s) Jian-Yang Li Lucille Le Corre Vishnu Reddy Mark V Sykes Andreas Nathues Carle M Pieters MauroCiarniello Diego Turrini Lucy A McFadden Carol ARaymond Christopher T RussellInstitution(s) 1 Brown University 2 Institute of Geophysicsand Planetary Physics University of California at Los Angeles 3Instituto di Astrofisica e Planetologia Spaziali INAF 4 JetPropulsion Laboratory California Institute of Technology 5 MaxPlanck Institute for Solar System Research 6 NASA GoddardSpace Flight Center 7 Planetary Science Institute

10305 ndash Spectrophotometry of the Ceres surfaceThe Dawn spacecraft is in orbit around dwarf planet Ceres Theonboard Framing Camera (FC) is mapping the surface through aclear filter and 7 narrow-band filters at various observationalgeometries and image resolutions Generally Ceres appearance inthese images is affected by shadows and shading effects whichobscure the intrinsic reflective properties of the surface By meansof photometric modeling we remove these effects and reconstructthe surface reflectance for each of the FC filters creating albedoand color maps in the process Considering these maps in unisonprovides clues to the physical nature and composition of thesurface and the dominant geologic processes that shape thesurface We assess the nature of color variations in the visiblewavelength range for Ceres globally We identify which terrainsexpress the dominant colors and investigate why some areas areexceptions to the rule By correlating the color over the surface withgeologic units we find an relatively strong enhancement of thereflectance towards the blue end of the visible spectrum for recentimpacts and their ejecta

Author(s) Stefan Schroumlder Stefano Mottola Uri Carsenty Ralf Jaumann Uwe Keller Katrin Krohn Jian-Yang Li Klaus-Dieter Matz Lucy McFadden Katharina Otto Frank Preusker Thomas Roatsch Frank Scholten Katrin Stephan RolandWagner Carol Raymond Chris RussellInstitution(s) 1 DLR 2 Goddard Space Flight Center 3 JPL 4PSI 5 Technische Universitaumlt Braunschweig 6 UCLA

10306 ndash First Spectral Coverage of two regions onCeres in the far-UVWe present the first spectral observations of Ceres in thefar-ultraviolet along with new measurements in the near-UV andvisible as measured by HSTSTIS as part of Cycle 22 in August-September 2015 The observations are motivated by earlybroad-band UV observations [1][2][3] suggesting a UV absorptioncentered near 260 nm along with a very strong increase in UVreflectance into the far-UV (~160 nm) We have observed twocentral longitudes of Ceres ndash near 0degW and 120degW (this latter areaone of the regions in which Herschel detected water vapor) ndash usingthe G140L (~120-172 nm) G230L (~170-310 nm) and G430L(~300-570 nm) detectors We use the data to test a prediction ofgraphitized carbon on the surface and we look for signatures ofwater ice andor water vapor[1] Parker J W S A Stern P C Thomas M C Festou W JMerline E F Young R P Binzel L A Lebofsky (2002) Astron J123 549[2] Li et al (2006) Icarus 182 143-160[3] Rivkin A S J-Y Li R E Milliken L F Lim A J Lovell BE Schmidt L A McFadden B A Cohen (2011) Space Sci Rev 16395

Author(s) Amanda R Hendrix Faith Vilas Jian-Yang LiInstitution(s) 1 Planetary Science Institute

10307 ndash Ceresrsquo impact craters probes of near-surfaceinternal structure and compositionDawn Framing Camera images of Ceres have revealed the existenceof a heavily cratered surface Shape models derived from theseimages indicate that most (though not all) large craters are quitedeep up to 6 km for craters larger than 100 km in diameter Theretention of deep craters is not consistent with a simpledifferentiated internal structure consisting of an outer layercomposed solely of pure water ice (covered with a rocky lag)overlying a rocky core Here we use finite element simulations toshow that for Ceresrsquo relatively warm surface temperatures thetimescale required to completely flatten a crater 60-km in diameter(or greater) is less than 100 Myr assuming a relatively pure outerice layer (for ice grain sizes le 1 cm) Preserving substantialtopography requires that the viscosity of Ceresrsquo outer-most layer(25-50 km thick) is substantially greater than that of pure waterice A factor of ten increase in viscosity can be achieved byassuming the layer is a 5050 ice-rock mixture by volumehowever our simulations show that such an increase is insufficientto prevent substantial relaxation over timescales of 1 Gyr Only

6 25 7 3

1 4 3 73

7 7 77 5 1

3 3 64 2

1 1 11 5 1 4

1 2 1 11 1 1

1 3 6

1 1 1

8

particulate volume fractions greater than 50 provide an increasein viscosity sufficient to prevent large-scale rapid relaxation Suchvolume fractions suggest an outer layer composed of frozensoilregolith (ie more rock than ice by volume) a very salt-richlayer or both Notably while most basins appear quite deep a fewrelatively shallow basins have been observed (eg Coniraya)suggesting that relaxation may be occurring over very longtimescales (eg 4 Ga) that Ceresrsquo interior is compositionally andspatial heterogeneous andor that temporal evolution of theinterior structure and composition has occurred If these shallowbasins are in fact the result of relaxation it places an upper limit onthe viscosity of Ceresrsquo outer-most interior layer implying at leastsome low-viscosity material is present and likely eliminating thepossibility of a purely rocky (homogeneous low density highporosity) interior

Author(s) Michael T Bland Carol Raymond Ryan Park Paul Schenk Tom McCord Vishnu Reddy Scott King MarkSykes Chris RussellInstitution(s) 1 Bear Fight Institute 2 Department ofGeoscience Virginia Tech 3 Lunar and Planetary Institute 4NASA JPL 5 Planetary Science Institute 6 University ofCalifornia Los Angeles IGPPEPSS 7 USGS Astrogeology

10308 ndash Geomorphological evidence for pervasiveground ice on Ceres from Dawn dataFive decades of observations of Ceres have explored the likelihoodthat the innermost dwarf planet boasts an ice rich bulkcomposition We report geomorphological evidence from DawnFraming Camera data suggesting that its surface has likely beenshaped by surface andor shallow subsurface ice includingpossible evaporative and flow processes within silicate-icemixtures Here we highlight three classes of features that possessstrong evidence for ground ice First ubiquitous craters withscallop-shaped rims in some cases ldquobreachedrdquo are characterized bymass wasting processes and by the recession of crater walls inasymmetric patterns these could be influenced by processesanalogous to those in sublimating ice-rich terrain on Mars andthose formed by mass wasting in terrestrial glaciated regions Thedegradation of crater walls appears to be responsible for the nearlycomplete removal of some craters particularly at low latitudesSecond several high latitude high elevation craters feature lobedflows that emanate from cirque-shaped head walls and bearstrikingly similar morphology to flows on other ice-rich planetarysurfaces Possible similarities to terrestrial rock glaciers includelobate toes and indications of furrows and ridges consistent withflow of ice-cored or ice-cemented material Other lobed flowspersist at the base of crater walls and mass wasting features Manyflow features evidently terminate at ramparts Third there arefrequent irregular domes peaks and mounds within crater floorsthat depart from traditional crater central peaks or peak complexesIn some cases the irregular domes show evidence for high albedoor activity One possible formation scenario could include extrusionand refreezing of subsurface water forming domes in similarprocesses to ice lens formation in pingos The distribution of theseclasses of features including latitudinal variation in theirabundance andor appearance suggests that ground ice is a keycontroller of geology on Ceres and that ice content within thesurface and subsurface is spatially varied andor activated byenergetic events

Author(s) Britney E Schmidt Jennifer Scully Heather TChilton Kynan Hughson Hanna Sizemore Michael Bland Paul Schenk Andreas Nathues Thomas Platz David POBrien Shane Byrne Norbert Schorghofer EleonoraAmmanito Christopher T Russell Carol A Raymond MariaCristina DeSanctis Simone Marchi Jian-Yang Li LucilleLeCorre Vishnu Reddy Harald Hiesinger Ralf Jaumann Mark Sykes Thomas McCordInstitution(s) 1 Bear Fight Institute 2 DLR 3 GeorgiaInstitute of Technology 4 IFA University of Hawaii 5 INAF 6JPL 7 LPI 8 MPS 9 PSI 10 SWRI 11 UCLA 12 University ofArizona 13 University of Muenster 14 USGS

10309 ndash Thermal Stability of Ice on Ceres with Rough

TopographyThe dwarf planet Ceres may have an ice-rich crust and subsurfaceice exposed by impacts or endogenic activity would be subject tosublimation The ldquobright spotsrdquo recently discovered by the Dawnmission on the illuminated surface of Ceres have promptedspeculation regarding their possible icy composition and theyouthful age this might imply Furthermore sublimation of ice atthe surface or in the interior of Ceres could explain water vaporobserved on more than one occasion in the exosphere Weinvestigated the possible distribution and lifetimes of water ice andother volatiles on Ceres using detailed thermal models includingrealistic thermophysical properties and surface roughnessTopographic shadowing creates polar cold traps where a small butnon-negligible fraction (~04) of Ceres surface is perenniallybelow the ~110 K criterion for 1 Gyr of H O ice stability Theseareas are found above 60deg latitude Other molecules (CH OHNH SO CO ) may be cold-trapped in smaller abundances Amodel for the transport gravitational escape and photoionizationof H O molecules suggests net accumulation in the cold traps Atlatitudes 0deg - 30deg ice is stable under solar illumination only briefly(~10-100 yr) unless it has high albedo and thermal inertia inwhich case lifetimes of gt 10 yr are possibleBuried ice is stable within a meter for gt 1 Gyr at latitudes higherthan ~50deg An illuminated polar cap of water ice would be stablewithin a few degrees of the poles only if it maintained a high albedo(gt 05) at present obliquity If the obliquity exceeded 5deg in thegeologically recent past then a putative polar cap would have beenerased Finally a small hemispheric asymmetry exists due to thetiming of Ceres perihelion passage which would lead to adetectable enhancement of ice in the northern hemisphere if theorbital elements vary slowly relative to the ice accumulation rateOur model results are potentially testable during the Dawn sciencemission

Author(s) Paul O Hayne Oded AharonsonInstitution(s) 1 Jet Propulsion Laboratory 2 WeizmannInstitute of Science

10310D ndash Geophysics and geochemistry intertwinedModeling the internal evolution of Ceres Pluto andCharonLiquid water likely shaped dwarf planet evolution observations[12] and models [3-5] suggest aqueous alteration of silicates orvolatiles accreted by these worlds Driven by thermo-physicalsettings aqueous alteration also feeds back on dwarf planetevolution in unconstrained ways Can rocky dwarf planet corescrack increasing the water-rock interface Might radionuclides beleached into fluids changing the distribution of this chief heatsource What is the fate of antifreezes on which may hingelong-term liquid persistence Is volcanism favored or impededWhat are predicted cryomagma compositionsWe have modeled silicate core fracturing [6] geochemicalequilibria between chondritic rock and aqueous fluids [7] andprerequisites for cryovolcanism [8] These models coupled to anevolution code [3] allow us to study geophysicschemistryfeedbacks inside dwarf planetsIce-rock differentiation even partial [910] yields a rocky brittlecore cracked by thermal stresses liquid circulation through corecracks transports heat into the ice mantle yielding runawaymelting that quickly ceases once convection cools the mantle to itsfreezing point [6] Hot fluids can leach radionuclides at highwaterrock ratios (WR) NH antifreeze can turn intoNH -minerals at low WR [7] Volatile (chiefly CO) exsolutionenables explosive cryovolcanism [8] this may explain Plutorsquosyoung CO-rich Tombaugh RegioApplied to Ceres such models are consistent with pre-Dawn andDawn data [11] provided Ceres partially differentiated into a rockycore and muddy mantle [10] They suggest Ceresrsquo hydrated surface[2] was emplaced during a Al-fueled active phase and predict itsbright spots result from cryovolcanic fluids squeezed by mantlerefreezing and effusing through pre-existing subsurface cracks [11][1] Cook et al 2007 ApJ 6631406[2] Milliken amp Rivkin 2009 Nat Geosc 2258[3] Desch et al 2009 Icarus 202694

7 4 43 1 5 2

5 6

3 63 11 9 14

7 8 89 12 4

11 11 65 10 9

9 9 13 29 1

23

3 2 2

2

4

1 2

34

26

9

[4] Castillo-Rogez et al 2010 Icarus 205443[5] Robuchon amp Nimmo 2011 Icarus 216426[6] Neveu et al 2015 JGR 120123[7] Neveu et al in prep[8] Neveu et al 2015 Icarus 24648[9] Rubin et al 2014 Icarus 236122[10] Travis et al 2015 46th LPSC abstr 2360[11] Neveu amp Desch in review

Author(s) Marc Neveu Steven J Desch Julie C Castillo-RogezInstitution(s) 1 Arizona State University 2 Jet PropulsionLaboratory

10311D ndash The geological evolution of asteroid Vestafrom Dawn orbital observations and meteoriteanalogsAsteroid Vesta is a survivor protoplanet and the knowledge it yieldsis essential to understand the early stages of planet formation Tosupport mineralogical characterization of its surface mineralogicaland near-IR (07-25 microm) analyses of 24 howardite-eucrite-diogenite meteorites were performed (Ruesch et al 2015) Therange of observation geometries within which the compositionalvariations can be distinguished from geometry effects weredetermined and empirical calibrations relating the position ofabsorption bands to average pyroxene compositions wereestablished Next the empirical calibrations were applied toreflectance spectra of Vesta from the Dawns near-IR spectrometer(VIR) revealing that Vestaacutes iron-poor terrains have a Fs Wopyroxene whereas iron-rich terrains have an average Fs Wo(Ruesch et al 2015) This confirms that despite a homogeneousregolith different terrains are preserved and formed during anearly magmatic period To further characterize Vestarsquos igneousprocesses a search for olivines near-IR signature was performedConcentrations of olivine-enriched areas were found in thenorthern hemisphere (Ruesch et al 2014a) corroborating otherstudies As such location was unexpected the geology of thenorthern was characterized with the Dawn Framing Cameraobservations (Ruesch et al 2014b) The hemisphere is composedof an ancient (pre-Veneneian epoch) densely cratered terrainpartly disrupted by a subdued tectonic system (Veneneian epoch)Olivine-enriched materials are exposed recently (Marcian epoch)by impacts and mass wasting but most of their parent lithologiesare probably the result of shallow magmatic activity during thepre-Veneneian The presence of olivine-enriched material in thiscontext and not as exposure of an olivine-rich mantle partlycontradicts many pre-Dawn concepts of Vestan differentiation Asan alternative to the HED parent body model few scenarios existfor Vestas early evolution and none provide consistentexplanation for the entire range of observations reported in thiscomprehensive mineralogical and geological study This revealsthat protoplanets experienced a complex differentiation processwhich is only partly understood

Author(s) Ottaviano RueschInstitution(s) 1 NASA Goddard Space Flight CenterORAU

104 ndash Planetary Rings10401 ndash Constraints on Chariklos rings from HST andVLT observationsIn June 2013 a stellar occultation revealed for the first time everthe presence of two dense and narrow rings around a small objectof the solar system the Centaur (10199) Chariklo (Braga-Ribas etal Nature 508 72 2014) This body follows an eccentric orbitbetween Saturn and Uranus with perihelion and apheliondistances of 131 and 185 AU Due to Uranus perturbations itsorbit is unstable on the very short time scale of ~10 Myr (Horner atal MNRAS 354 798 2004) The two rings (C1R and C2Rrespectively) have orbital radii a = 3906plusmn33 km and a =4048plusmn33 km and typical widths W ~65 km and W ~2km optical depths τ ~ 04 and τ ~ 006 with a gap of ~9km between the two Chariklos radius R ~ 120 km (Duffard et al

AA 568 A79 2014 Fornasier et al AA 518 L11 2014) implies thatthe ring system lies at 33-34 R farther away than the classicalRoche limit of 24 R that would be obtained for spherical ringparticles with the same density as CharikloTo better understand Chariklos surroundings and thus the originof the rings direct imaging of Chariklo has been performed usingHST and VLT with respectively 3 visits and 2 runs performedbetween April and August 2015 The HST images were obtainedwith the WFC3UVIS camera with filters F300X (250-350 nm)F475X (400-650 nm) and F350LP (300-1000 nm) and typical PSFsize of 30 milli-arcsec (mas) corresponding to about 300~km atChariklo Conversely the SPHERE high contrast instrument atESO VLT provided images in the near IR (Y J and H bands) withtypical expected PSF sizes of 30-40 mas (300-400~km atChariklo) The main goals of those observations were (1) obtaindirect images of the rings confirming their geometry and theirorientation (2) derive multi-wavelength photometry thusconstraining their composition (concerning in particular thepresence of water ice) (3) perform a deep search of small satellites(down to a few km in diameter) (4) faint dusty rings aroundChariklo (down to about τ ~10 -10 ) and (5) search possiblecometary jets or coma akin to what is observed around anotherCentaur Chiron (Ortiz et al AA 576 A8 2015) Premiminaryresults obtained from those observations will be presented

Author(s) Bruno Sicardy Marc W Buie Gustavo Benedetti-Rossi Felipe Braga-Ribas Julio I Bueno de Camargo ReneDuffard Jose Luis Ortiz Damien Gratadour ChristopheDumasInstitution(s) 1 Federal University of Technology(UTFPRDAFIS) - Paranaacute 2 Instituto de Astrofiacutesica de AndaluciacuteaCSIC 3 Observatoire de ParisLESIA and Univ Paris 6 4Observatorio Nacional 5 SWRI 6 Thirty-Meter-TelescopeInternational Observatory

10402 ndash Chariklos size shape and orientation fromstellar occultationsChariklo is the largest Centaur object known to date and it issurrounded by dense and narrow rings (Braga-Ribas et al Nature508 72 2014) The size shape and orientation of the central bodyare important parameters to better understand the dynamics of theringsIn that context we have analyzed three stellar occultations byChariklo and its main ring observed on June 3 2013 April 29 2014and June 28 2014 Elliptical limb fitting to Chariklorsquos main bodyoccultation chords has been performed where we denote a (respb) the semi-major (resp semi-minor) axis of the limb Preliminaryresults indicate that Chariklorsquos limb is elliptical with axes ratioba~089 We obtain a~133 km and b~119 km providing anequivalent radius of R =radic(ab)~126 km The rms dispersion ofthe fit about 4 km is compatible with local topographic features ona small icy body For comparison an equivalent radius of R =119plusmn5 km based on thermal data is given by Fornasier et al AA518 L11 2014 while Duffard et al AA 568 A79 2014 estimate a=122 km and b= 117 kmOur results are obtained under the simplifying assumption that themain ring is circular and that its center coincides with that ofChariklo Caveats and error bars will be discussed and dynamicalimplications will be presented In particular rough estimations ofthe ring apsidal precession rates will be given as well as constraintson Chariklos density

1 12

30 547 14

1

C1R C2RC1R C2R

C1R C1RC

CC

-5 -6

3 54 1 4

2 2 36

equiv

equiv

10

Author(s) Diane Beacuterard Bruno Sicardy Marcelo Assafin Felipe Braga-Ribas Julio Camargo Roberto Vieira Martins Rene Duffard Jose Luis Ortiz Colin Snodgrass EmmanuelJehin Joe Pollock Franccedilois Colas Jean Luc Dauvergne Jean Lecacheux Lucie Maquet Amanda A Sickafoose KarlLudwig Bath Wolfgang Beisker Rodrigo LeivaInstitution(s) 1 Ciel amp Espace 2 Federal University ofTechnology (UTFPRDAFIS) - Paranaacute 3 Institut dAstrophysiquede lUniversiteacute de Liegravege 4 Instituto de Astrofiacutesica de Andaluciacutea -CSIC 5 International Occultation Timing Association 6Observatoire de Paris - LESIA amp UPMC 7 Observatoire de ParisIMCCE UPMC CNRS 8 Observatoacuterio do Valongo - UFRJ 9Observatorio Nacional 10 Physics and Astronomy DepartmentAppalachian State University 11 South African AstronomicalObservatory amp MIT 12 The Open University

10403D ndashParticle Sizes in Saturnrsquos Rings from DiffractionSignals in Cassini UVIS Occultation DataSince its arrival at Saturn in 2004 the Cassini spacecraft hasilluminated many aspects of the planetrsquos extensive ring systemincluding its vast range of particle sizes Constraints on the particlesize distribution are critical for understanding the evolution of thering system Our investigation focuses on modeling diffractionsignals in occultation data from the Cassini Ultraviolet ImagingSpectrograph (UVIS) to measure the population of the smallestparticles in Saturnrsquos ringsOccultation data from Cassinirsquos Radio Science Subsystem and theVisual and Infrared Mapping Spectrometer also providemeasurements of the size distribution The amount of lightdiffracted by the occulting particles is a reflection of the ratio of thewavelength of light and the radius of the particles We can utilizethe diffraction signals at different wavelengths measured bydifferent instruments to describe the particle size distribution ofSaturnrsquos ringsThe UVIS wavelength bandpass 512-180 nm is the shortest ofthese instruments making it most sensitive to the smallestparticles We model the diffraction signals detected in stellaroccultation data at ring edges and find that Saturnrsquos outer A ringlacks any significant population of sub-mm particles but theaverage size of the smallest particles decreases from ~15 cm at theEncke Gap to ~4 mm at the outer edge of the A ring Diffractionspikes have also been identified at the edge of the B ring and atsharp edges of ringlets in the C ring and Cassini Divisionsuggestive of mm-sized particles throughout the rings We analyzesolar occultations by the F ring and sporadically detect diffractedlight indicating the population of sub-mm particles responsible forthe diffraction is transient or spatially variable Comparisons withimages from the Cassini Imaging Science Subsystem suggest thatthese diffraction signals coincide with nearby collisional events inthe F ring core This may indicate that such events release dustparticles producing a diffraction signature in the UVIS dataWe will present an overview of the concerted efforts to measure theparticle size distribution of Saturnrsquos rings and the recent resultsfrom our investigation of UVIS occultation data

Author(s) Tracy M Becker Joshua E Colwell Larry WEsposito Nicholas O Attree Carl D MurrayInstitution(s) 1 LASP University of Colorado Boulder 2Queen Mary University of London 3 University of Central Florida

10404 ndash A traveling feature in Janus spiral densitywavesEvery 40 years on 21 January the Saturnian co-orbital satellitesJanus and Epimetheus move radially and switch relative positionsThis swap also alters the locations of the resonances within therings corresponding to these moons In stellar occultations by the Aand B rings observed by the Cassini Ultraviolet ImagingSpectrographrsquos High Speed Photometer between 2005 and 2015we report the detection of many density-wave interferencestructures as a result of these orbital swapsMost prominent in the Janus 21 43 54 and 65 resonanceregions is a soliton-like traveling wave which propagates throughthe rings This wave moves at approximately twice the group

velocity of the A-ring spiral density waves and at a similar velocityto that of the Janus 21 density wave in the B ring The opticaldepth of the B ring near the Janus 32 spiral density wave is toogreat for it to be visible and no similar traveling features weredetected within three Mimas and Prometheus density waves

Author(s) Morgan Rehnberg Larry W Esposito Zarah LBrown Miodrag Sremčević Nicole AlbersInstitution(s) 1 CULASP

10405 ndash An analysis of the A rings outer edge probesSaturns interiorWe present a study of the behavior of the outer edge of Saturns Aring using images and occultation data obtained by the Cassinispacecraft over a period of 8 years from 2006 to 2014 More than5000 images and 150 occultations of the A ring outer edge areanalyzed Our fits confirm the expected response to the Janus 76Inner Lindblad resonance (ILR) between 2006 and 2010 whenJanus was on the inner leg of its regular orbit swap withEpimetheus During this period the edge exhibits a regular 7-lobedpattern with an amplitude of 128 km and one minimum alignedwith the orbital longitude of Janus as has been found by previousinvestigators However between 2010 and 2014 theJanusEpimetheus orbit swap moves the Janus 76 LR away fromthe A rings outer edge and the 7-lobed pattern disappearsIn addition to the perturbation forced by Janus we have identifieda variety of normal modes at the edge of the A ring with values ofm ranging from 3 to 18 and appropriate pattern speeds Thesemodes may represent waves trapped in resonant cavities at theedge (Spitale and Porco 2010 Nicholson et al 2014)We further identified some other signatures consistent withtesseral resonances that might be associated with inhomogeneitiesin Saturns interior This result is consistent with previous studies(Hedman et al 2009 2014) These signatures may provideinformation about differential rotation in Saturns interior

Author(s) Maryame El Moutamid Philip Nicholson PeterGierasch Richard French Joseph Burns Matthew Tiscareno Matthew Hedman Carl MurrayInstitution(s) 1 Cornell University 2 Queen Mary Universityof London 3 SETI Institue 4 University of Idaho 5 WellesleyCollege

10406 ndash Analysis and Dynamics of a SaturnianSatellite at the A Ring EdgeAn object found (Murray et al 2014) at the edge of Saturns A ringpresents a unique opportunity to investigate Charnoz et al (2010)ssuggestion that moonlets form in the rings as well as to conductdynamical studies near the ring edge We track this object inCassini images to learn its connection if any to Janus co-rotationand Lindblad resonances before and after the 2014 orbital shift ofJanus and Epimetheus We find that it may have undergone anabrupt eight-kilometer shift in semi-major axis in 2013 which isunexplained by resonant effects but may be due to a collision withsomething in or outside of the rings Furthermore we propose thepotential existence of another object near the ring edge whichwould obviate any change in the semi-major axis of Murraysobject Such an object may have been captured in co-rotationresonance with Janus between 2010 and 2014

Author(s) Christie J Trimble Maryame El Moutamid Philip D Nicholson Joseph A Burns Carl D Murray NicholasJ CooperInstitution(s) 1 Arizona State University 2 Cornell University3 Queen Mary University of London

10407 ndash Wisps in the outer edge of the Keeler GapSuperposed upon the relatively smooth outer edge of the KeelerGap are a system of wisps which appear to be ring materialprotruding inward into the gap usually with a sharp trailing edgeand a smooth gradation back to the background edge location onthe leading side (Porco et al 2005 Science) The radial amplitudeof wisps is usually 05 to 1 km and their azimuthal extent isapproximately a degree of longitude (~2400 km) Wisps are likely

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11

caused by an interplay between Daphnis (and perhaps othermoons) and embedded moonlets within the ring though thedetails remain unclearAside from the wisps the Keeler Gap outer edge is the only one ofthe five sharp edges in the outer part of Saturns A ring that isreasonably smooth in appearance (Tiscareno et al 2005 DPS)with occultations indicating residuals less than 1 km upon apossibly non-zero eccentricity (RG French personalcommunication 2014) The other four (the inner and outer edgesof the Encke Gap the inner edge of the Keeler Gap and the outeredge of the A ring itself) are characterized by wavy structure atmoderate to high spatial frequencies with amplitudes ranging from2 to 30 km (Tiscareno et al 2005 DPS)We will present a catalogue of wisp detections in Cassini imagesWe carry out repeated gaussian fits of the radial edge location inorder to characterize edge structure and visually scan those fittededges in order to detect wisps With extensive coverage in longitudeand in time we will report on how wisps evolve and move bothwithin an orbit period and on longer timescales We will also reporton the frequency and interpretation of wisps that deviate from thestandard morphology We will discuss the implications of ourresults for the origin and nature of wisps and for the larger pictureof how masses interact within Saturns rings

Author(s) Matthew S Tiscareno Ethan G ArnaultInstitution(s) 1 Cornell University 2 SETI Institute

10408 ndash Strong orbital expansion of Saturnrsquos innerice-rich moons through ring torques and mutualresonances during their accretion from a massive ringSaturn has a diversity of moons with possibly diverse origins Titanlikely formed in Saturnrsquos sub-nebula (eg Canup amp Ward 2006)The small moons interior to Mimas are likely recent aggregates ofringrsquos material spreading through the Roche limit (Charnoz et al2010) The origin of the mid-size moons Mimas through Rhea isdebated Charnoz et al (2011) considered a massive ice-rock ringand strong tidal dissipation in Saturn (Q ~ 10 ) and found thatmoons out to Rhea could be spawned from such a ring Howeversuch a small value for Q for Saturn is debated In addition captureinto mutual Mean Motion Resonances (MMR) and resultingeccentricity growth (not included in the Charnoz et al (2011)model) could lead to orbital destabilization as the moons tidallyexpand over such large distances (Peale amp Canup 2015)Here we consider weak planetary tides (Q ge 10 ) and investigatewhether Mimas Enceladus and Tethys could have been spawnedfrom a massive ice ring (Canup 2010) In this scenario the rock inthese moons would be delivered by material from outside the ringseg by heliocentric impactors during the LHB (Canup 2013) Wehave expanded a numerical model developed to study the Moonrsquosaccretion (Salmon and Canup 2012 2014) which couples ananalytic Roche-interior disk model to the N-body code SyMBA(Duncan et al 1998) for satellites so that we can directly track theiraccretion and mutual interactions (including MMRs) as well astheir tidal interaction with the planet We consider an initially largeSaturn (Fortney et al 2007) and its progressive contraction whichimpacts the strength of tides and the location of the corotationresonance We perform simulations with and without Dione andRhea and study the influence of tidal dissipation into the moonsWe find that recoil of the moons due to ring torques together withcapture of moons into MMRs can produce a distribution similar tothat observed If tidal dissipation in the moons was weak we showthat even if the final moons have low eccentricity and inclinationthey experience a phase of high values that is subsequentlydamped by mutual collisions The latter seem to typically preservethe overall stability of the system

Author(s) Julien Salmon Robin M CanupInstitution(s) 1 Southwest Research Institute

10409 ndash Non-Linear Dynamics of Saturnrsquos RingsNon-linear processes can explain why Saturnrsquos rings are so activeand dynamic Ring systems differ from simple linear systems in twosignificant ways 1 They are systems of granular material whereparticle-to-particle collisions dominate thus a kinetic not a fluid

description needed We find that stresses are strikinglyinhomogeneous and fluctuations are large compared toequilibrium 2 They are strongly forced by resonances which drivea non-linear response pushing the system across thresholds thatlead to persistent statesSome of this non-linearity is captured in a simple Predator-PreyModel Periodic forcing from the moon causes streamlinecrowding This damps the relative velocity and allows aggregates togrow About a quarter phase later the aggregates stir the system tohigher relative velocity and the limit cycle repeats each orbitSummary of Halo Results A predator-prey model for ringdynamics produces transient structures like lsquostrawrsquo that can explainthe halo structure and spectroscopy This requires energeticcollisions (v asymp 10msec with throw distances about 200kmimplying objects of scale R asymp 20km)Transform to Duffing Eqn With the coordinate transformation z= M the Predator-Prey equations can be combined to form asingle second-order differential equation with harmonic resonanceforcingRing dynamics and history implications Moon-triggered clumpingat perturbed regions in Saturnrsquos rings creates both high velocitydispersion and large aggregates at these distances explaining bothsmall and large particles observed there We calculate thestationary size distribution using a cell-to-cell mapping procedurethat converts the phase-plane trajectories to a Markov chainApproximating the Markov chain as an asymmetric random walkwith reflecting boundaries allows us to determine the power lawindex from results of numerical simulations in the tidalenvironment surrounding Saturn Aggregates can explain manydynamic aspects of the rings and can renew rings by shielding andrecycling the material within them depending on how long themass is sequestered We can ask Are Saturnrsquos rings a chaoticnon-linear driven system

Author(s) Larry W EspositoInstitution(s) 1 Univ of Colorado

10410 ndash NanoRocks Experimental Study ofCollisional Damping and Aggregation at LowVelocitiesThe NanoRocks experiment on the International Space Stationconsists of 8 separate sample trays of particles from ~01 mm ndash 20mm in diameter that undergo collisional evolution Themicrogravity environment of the ISS allows collision speeds of lessthan 1 mms to be studied At these speeds the experimentreproduces the velocity dispersion found in unperturbed regions ofSaturnrsquos rings Observations of the rings from Cassini instrumentshint at aggregation and fragmentation of clumps depending on thelocal surface mass density particle size distribution and velocitydispersionThe eight NanoRocks samples include plastic beads copper glassand JSC-1 lunar regolith simulant The samples are shaken at 1minute intervals to provide initial collision velocities of a few cmsand video is recorded of the collisional evolution of the particlesamples We derive mean coefficients of restitution for thedifferent samples based on the damping of the mean velocitydispersion as well as tracking of individual particle trajectories Theevolution of the velocity distribution is consistent with a uniformrandom distribution of the coefficient of restitution independentof collision velocity This is consistent with results of Heiszligelmannet al (Icarus Vol 206 pp 424-430 2010) using larger icy particlesWe also find the onset of cluster formation at speeds of a fewmms We will present our results and discuss applications tomodels of the collisional evolution of Saturnrsquos rings

Author(s) Joshua E Colwell Julie Brisset Adrienne RDove Jessica Metzger Allison RasconInstitution(s) 1 University of Central Florida

10411 ndash Impact of Saturn Main Ring Mass oninterpretation of Pioneer 11 and Cassini SOI RadiationMeasurements Across the RingsThe Pioneer 11 (1979) and Cassini Orbiter (2004) missionsmeasured the energetic particle and gamma ray flux environments

2 1

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4

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12

across the A B and outer C rings of Saturn This radiationoriginates as secondary proton neutron electron and gamma rayemissions from the interaction of high-energy (gt 20 GeV) galacticcosmic ray protons and other ions with bulk ice material in therings and is sensitive to the surface mass density of the rings ThePioneer 11 analysis from the University of Chicago High EnergyTelescope published in 1985 was consistent with a average surfacedensity of about 50 gcm assuming pure water ice and a totalring mass of 27x10 Saturn masses (M ) This independently-derived value confirmed the post-Voyager result of 3x10 Mfrom radio and stellar occultations and from observed damping ofdensity waves in the rings Although some later ring models in theCassini mission era (2004 - present) allow for a greater mass by anorder of magnitude the latest density wave analysis from Cassiniindicates that the Pioneer-Voyager value may be correct GEANTradiation transport simulations have been performed to update thering radiation model and enable ongoing assessments of thePioneer 11 HET and Cassini MIMILEMMS responses to thisradiation The O gas production by radiation chemistry within thering material is also estimated as a function of ring mass forcomparison to Cassini and earlier measurements of the ringatmosphere and ionosphere More massive rings would producemore O

Author(s) John F Cooper Steven J Sturner Edward CSittler Jr Peter Kollmann Elias Roussos Robert E JohnsonInstitution(s) 1 Applied Physics Laboratory Johns HopkinsUniversity 2 Max Planck Institute for Solar System Research 3NASA Goddard Space Flight Center 4 University of Virginia

105 ndash Pluto System III--Plutos Atmosphere10501 ndash Radio Occultation Measurements of PlutorsquosAtmosphere with New HorizonsThe reconnaissance of the Pluto System by New Horizons includedradio occultations at both Pluto and Charon This talk will presentthe latest results from the Pluto occultation The REX instrumentonboard New Horizons received and recorded uplink signals fromtwo 70-m antennas and two 34-m antennas of the NASA DeepSpace Network - each transmitting 20 kW at 42-cm wavelength -during a diametric occultation by Pluto At the time this was writtenonly a short segment of data at occultation entry (193degE 17degS) wasavailable for analysis The REX measurements extendunequivocally to the surface providing the first direct measure ofthe surface pressure and the temperature structure in Plutorsquos loweratmosphere Data from occultation exit (16degE 15degN) are scheduledto arrive on the ground in late August 2015 Those observationswill yield an improved estimate of the surface pressure a secondtemperature profile and a measure of the diameter of Pluto with aprecision of a few hundred meters This work is supported by theNASA New Horizons Mission

Author(s) David P Hinson Ivan Linscott Len Tyler MikeBird Martin Paetzold Darrell Strobel Mike Summers WillWoods Alan Stern Hal Weaver Cathy Olkin Leslie Young Kimberly Ennico Randy Gladstone Tommy Greathouse JoshKammer Alex Parker Joel Parker Kurt Retherford EricSchindhelm Kelsi Singer Andrew Steffl Con Tsang MaartenVersteegInstitution(s) 1 Applied Physics Laboratory 2 George MasonUniversity 3 Johns Hopkins University 4 NASA Ames ResearchCenter 5 SETI Institute 6 Southwest Research Institute 7Stanford University 8 SwRI 9 University of Bonn 10University of Cologne

10502 ndash Discovery of Hazes in Plutos AtmosphereThe New Horizons spacecraft made the first reconnaissance of thePluto-Charon system on Jul 14 2015 The Long RangeReconnaissance Imager (LORRI) on New Horizons obtainedimages of Pluto and Charon on approach near closest approachand on departure The departure images obtained at high solarphase angles unexpectedly revealed that Plutorsquos atmosphere ishazy The haze in Plutorsquos atmosphere was detected in each of five

images obtained in two separate observations on Jul 14 and on Jul26 at solar phase angles of 167deg and 165deg respectively The hazeextends to altitudes of at least 150 km above Plutorsquos surface withevidence for layering andor gravity waves We will present thehaze observations and discuss derived physical properties andimplications for the atmosphere and its interactions with thesurface including estimates for the rate of deposition of hazeparticles on the surface of PlutoThis work was supported byNASAs New Horizons Project

Author(s) Andrew F Cheng Randy Gladstone MichaelSummers Alex Parker John Spencer Leslie Young HalWeaver Kim Ennico Cathy Olkin Alan SternInstitution(s) 1 George Mason 2 Johns Hopkins APL 3Southwest Research

10503 ndash Haze in Plutos atmosphere Results fromSOFIA and ground-based observations of the 2015June 29 Pluto occultationWe observed the 29 June 2015 occultation by Pluto from SOFIAand several ground-based sites in New Zealand Pre-eventastrometry (described in Zuluaga et al this conference) allowed usto navigate SOFIA into Plutos central flash (Person et al thisconference) Fortuitously the central flash also fell over the MtJohn University Observatory (Pasachoff et al this conference) Wecombine all of our airborne and ground-based data to produce ageometric solution for the occultation and to investigate the state ofPlutos atmosphere just two weeks before the New Horizonsspacecrafts close encounter with Pluto We find that theatmosphere parameters at half-light are unchanged from ourobservations in 2011 (Person et al 2013) and 2013 (Bosh et al2015) By combining our light-curve inversion with recent radiusmeasurements from New Horizons we find strong evidence for anextended haze layer in Plutos atmosphere See also Sickafoose etal (this conference) for an evaluation of the particle sizes andpropertiesSOFIA is jointly operated by the Universities Space ResearchAssociation Inc (USRA) under NASA contract NAS2-97001 andthe Deutsches SOFIA Institut (DSI) under DLR contract 50 OK0901 to the University of Stuttgart Support for this work wasprovided by NASA SSO grants NNX15AJ82G (Lowell Observatory)NNX10AB27G (MIT) and NNX12AJ29G (Williams College) andby the National Research Foundation of South Africa

Author(s) A S Bosh M J Person C A Zuluaga A ASickafoose S E Levine J M Pasachoff B A Babcock EW Dunham I McLean J Wolf F Abe E Becklin T ABida L P Bright T Brothers G Christie P L Collins R FDurst A C Gilmore R Hamilton H C Harris CJohnson P M Kilmartin M R Kosiarek K Leppik S ELogsdon R Lucas S Mathers C J K Morley P Nelson H Ngan E Pfuumlller T Natusch H-P Roumlser S Sallum M Savage C H Seeger H Siu C Stockdale D Suzuki T Thanathibodee T Tilleman P J Tristram J Van Cleve C Varughese L W Weisenbach E Widen M WiedemannInstitution(s) 1 AAVSO 2 Auckland Observatory 3 Earth ampSky Limited 4 Hazelwood Observatory 5 Lowell Observatory 6MIT 7 Mt John University Observatory 8 Nagoya University 9Sandy Ridge Observatory 10 South African AstronomicalObservatory 11 Southern Cross Observatory 12 StewardObservatory 13 Sydney University 14 US Naval Observatory15 UCLA 16 United States Antarctic Program 17 UniversitaumltStuttgart 18 University of Canterbury 19 University of NotreDame 20 USRA 21 Williams College

10504 ndash Investigation of particle sizes in Plutosatmosphere from the 29 June 2015 occultationThe 29 June 2015 observations of a stellar occultation by Plutofrom SOFIA and ground-based sites in New Zealand indicate thathaze was present in the lower atmosphere (Bosh et al thisconference) Previously slope changes in the occultation lightcurve profile of Plutorsquos lower atmosphere have been attributed tohaze a steep thermal gradient andor a combination of the twoThe most useful diagnostic for differentiating between these effects

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has been observing occultations over a range of wavelengths hazescattering and absorption are functions of particle size and arewavelength dependent whereas effects due to a temperaturegradient should be largely independent of observationalwavelength The SOFIA and Mt John data from this event exhibitobvious central flashes from multiple telescopes observing over arange of wavelengths at each site (Person et al and Pasachoff et althis conference) SOFIA data include Red and Blue observationsfrom the High-speed Imaging Photometer for Occultations (HIPOat ~ 500 and 850 nm) First Light Infrared Test Camera(FLITECAM at ~1800 nm) and the Focal Plan Imager (FPI+ at ~600 nm) Mt John data include open filter g r i and nearinfrared Here we analyze the flux at the bottom of the light curvesversus observed wavelength We find that there is a distinct trendin flux versus wavelength and we discuss applicable Mie scatteringmodels for different particle size distributions and compositions (aswere used to characterize haze in Plutos lower atmosphere inGulbis et al 2015)SOFIA is jointly operated by the Universities Space ResearchAssociation Inc (USRA) under NASA contract NAS2-97001 andthe Deutsches SOFIA Institut (DSI) under DLR contract 50 OK0901 to the University of Stuttgart Support for this work wasprovided by the National Research Foundation of South AfricaNASA SSO grants NNX15AJ82G (Lowell Observatory) PANNX10AB27G (MIT) and PA NNX12AJ29G (Williams College)and the NASA SOFIA Cycle 3 grant NAS2-97001 issued by USRA

Author(s) Amanda A Sickafoose A S Bosh M JPerson C A Zuluaga S E Levine J M Pasachoff B ABabcock E W Dunham I McLean J Wolf F Abe T ABida L P Bright T Brothers G Christie P L Collins R FDurst A C Gilmore R Hamilton H C Harris CJohnson P M Kilmartin M R Kosiarek K Leppik SLogsdon R Lucas S Mathers C J K Morley TNatusch P Nelson H Ngan E Pfuumlller H-Proeserirsuni-stuttgartde S Sallum M Savage C HSeeger H Siu C Stockdale D Suzuki T Thanathibodee T Tilleman P J Tristam J Van Cleve C Varughese L WWeisenbach E Widen M WiedemannInstitution(s) 1 Astronomical Society of Victoria 2 AucklandObservatory 3 Earth amp Sky Limited 4 Hazelwood Observatory5 Lowell Observatory 6 MIT 7 Mt John UniversityObservatory 8 Nagoya University 9 Sandy Ridge Observatory10 South African Astronomical Observatory 11 Southern CrossObservatory 12 Steward Obs 13 Sydney University 14 USNaval Observatory 15 UCLA 16 United States AntarcticProgram 17 Universitaumlt Stuttgart 18 University of Canterbury19 University of Notre Dame 20 USRA 21 Williams College

10505 ndash Central Flash Analysis of the 29 June 2015OccultationAfter an extensive prediction effort the 29 June 2015 occultationby Pluto was observed from both airborne (StratosphericObservatory for Infrared Astronomy - SOFIA) and numerousground-based telescopes (Bosh et al - this meeting) Real-timeprediction updates allowed placement of the SOFIA telescope withits four detectors deep within the central-flash region of theatmospheric occultation Fortuitously the Mount John UniversityObservatory (Lake Tekapo New Zealand) was also within thecentral-flash region (Pasachoff et al ndash this meeting) Thishappenstance resulted in multiple central-flash detections inseveral colors from each facility allowing direct comparison ofdifferent areas of the central-flash evoluteHere we examine and discuss the central-flash signatures from thehighest signal-to-noise light curves from each facility The relativeorientations and asymmetries in the central flashes allow us to usethem to tightly constrain the lower atmospheric ellipticity andorientation of likely winds with respect to Plutorsquos figure The ratioof the two separate central flashes is also a strong constraint on thegeometric solution for the full occultation data set and theabsolute height of the central flashes with respect to those expectedfor a clear isothermal atmosphere places constraints on hazedensities and thermal gradients in Plutorsquos lower atmosphere Wecan also compare the central-flash signatures in several colors(similar to Sickafoose et al ndash this meeting) to establish bounds on

haze-particle sizes in the lower atmosphereSOFIA is jointly operated by the Universities Space ResearchAssociation Inc (USRA) under NASA contract NAS2-97001 andthe Deutsches SOFIA Institut (DSI) under DLR contract 50 OK0901 to the University of Stuttgart Support for this work wasprovided in part by NASA grants SSO NNX15AJ82G (LowellObservatory) PA NNX10AB27G (MIT) and PA NNX12AJ29G(Williams College) as well as the National Research Foundation ofSouth Africa and the NASA SOFIA Cycle 3 grant NAS2-97001issued by USRA

Author(s) Michael J Person A S Bosh A A Sickafoose CA Zuluaga S E Levine J M Pasachoff B A Babcock E WDunham I McLean J Wolf F Abe E Becklin T A Bida L P Bright T C Brothers G Christie P L Collins R F Durst A C Gilmore R Hamilton H C Harris C Johnson P MKilmartin M R Kosiarek K Leppik S E Logsdon RLucas S Mathers C J K Morley T Natusch P Nelson HNgan E Pfueller H-P Roeser S Sallum M Savage C HSeeger H Siu C Stockdale D Suzuki T Thanathibodee TTilleman P J Tristram J Van Cleeve C Varughese L WWeisenbach E Widen M WiedemannInstitution(s) 1 AAVSO 2 Auckland Observatory 3 Earth ampSky Limited 4 Hazelwood Observatory 5 Lowell Observatory 6MIT 7 Mt John University Observatory 8 Nagoya University 9Sandy Ridge Observatory 10 Southern Cross Observatory 11Steward Observatory 12 Sydney University 13 UCLA 14 UnitedStates Antarctic Program 15 Universitaumlt Stuttgart 16 Universityof Canterbury 17 University of Notre Dame 18 USNO 19 USRA20 Williams College

10506 ndash Detection of Atmospheric CO on Pluto withALMAWe observed Pluto and Charon using the Atacama LargeMillimetersubmillimeter Array (ALMA) interferometer inNorthern Chile on June 122 and June 1315 2015 just one monthprior to the New Horizons flyby of the system The configuration ofALMA at the time provided ~03 resolution allowing separation ofemission from Pluto and Charon This project targeted multiplescience goals including a search for HCN in Plutos atmosphere [1]and high precision measurements of the individual brightnesstemperatures of Pluto and Charon [2] also presented at thismeeting Here we report the high SNR detection of carbonmonoxide in the atmosphere of Pluto The CO(3-2) rotational lineat 345796 GHz (867 μm) was observed with 117 kHz spectralresolution for 45 min (on-source) on each date providing~35mJychannel RMS CO emission was clearly detected on bothdays with a contrast of ~65 mJy above the Pluto continuum and~18 MHz FWHM linewidth with the combined integrated lineSNR gt50 The presence of CO in Plutos atmosphere is expecteddue to its presence as ice on the surface in vapor pressureequilibrium with the atmosphere (eg [3][4]) and it waspreviously detected at modest SNR in the near-IR using the VLT[5] A preliminary assessment based upon the CO line wings showsthe fractional abundance of CO is 500-750 ppm consistent withthat found in [5] Further the shape of the line core emission(assuming a constant CO mixing ratio) suggests that theatmospheric temperature rises quickly from the surface to~100-110 K in the altitude range 20-70 km but decreases abovethat falling to about 70 K by 200 km altitude A detailed lineinversion analysis will be performed and results presented[1] Lellouch et al this meeting [2] Butler et al this meeting [3]Owen et al (1993) Science 261 pp 745ndash748 [4] Spencer et al(1993) In Pluto and Charon pp 435ndash473 Univ of Arizona PressTucson [5] Lellouch et al (2011) AampA 530 L4

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Author(s) Mark Gurwell Emmanuel Lellouch BryanButler Arielle Moullet Raphael Moreno Dominique Bockeleacutee-Morvan Nicolas Biver Thierry Fouchet Darek Lis AlanStern Leslie Young Eliot Young Hal Weaver JeremieBoissier John StansberryInstitution(s) 1 Harvard-Smithsonian Center For Astrophysics2 Institut de Radio-Astronomie Millimeacutetrique 3 Johns HopkinsUniversity Applied Physics Laboratory 4 National RadioAstronomy Observatory - Charlottesville 5 National RadioAstronomy Observatory - Socorro 6 Observatoire de Paris 7Southwest Research Institute 8 Space Telescope Science Institute

10507 ndash Detection of HCN in Plutos atmosphereWe report on the first detection of hydrogen cyanide in Plutosatmosphere obtained with the ALMA interferometer ALMAobservations of the HCN(4-3) line at 354505 GHz were conductedon June 122 and June 1315 2015 at ~03 spatial resolutionseparating Pluto from Charon with a 234 kHz spectral samplingThe HCN line was detected on both dates with a ~100 mJycontrast and a ~075 MHz FWHM linewidth The narrow linewidthand the absence of Lorentzian wings indicate that most of the HCNresides in Plutos upper atmosphere As on Titan HCN is anexpected photochemical product in a N2-CH4 atmosphere Datainterpretation in terms of the HCN abundancevertical distributionand comparison with photochemical models will be presented

Author(s) Emmanuel Lellouch Mark Gurwell BryanButler Arielle Moullet Raphael Moreno Dominique Bockeleacutee-Morvan Nicolas Biver Thierry Fouchet Darek Lis AlanStern Leslie Young Eliot Young Hal Weaver JeremieBoissier John StansberryInstitution(s) 1 Harvard-Smithsonian Center For Astrophysics2 Institut de Radio-Astronomie Millimeacutetrique 3 Johns HopkinsUniversity Applied Physics Laboratory 4 National RadioAstronomy Observatory - Charlottesville 5 National RadioAstronomy Observatory - Socorro 6 Observatoire de Paris 7Southwest Research Institute 8 Space Telescope Science Institute

10508 ndash Plutos Extended Atmosphere New HorizonsAlice Lyman-α ImagingPlutos upper atmosphere is expected to extend several planetaryradii proportionally more so than for any planet in our solarsystem Atomic hydrogen is readily produced at lower altitudes dueto photolysis of methane and transported upward to become animportant constituent The Interplanetary Medium (IPM) providesa natural light source with which to study Plutos atomic hydrogenatmosphere While direct solar Lyman-α emissions dominate thesignal at 1216 nm at classical solar system distances thecontribution of diffuse illumination by IPM Lyman-α sky-glow isroughly on par at Pluto (Gladstone et al Icarus 2015) Hydrogenatoms in Plutos upper atmosphere scatter these bright Lyαemission lines and detailed simulations of the radiative transfer forthese photons indicate that Pluto would appear dark against theIPM Lyα background The Pluto-Alice UV imaging spectrograph onNew Horizons conducted several observations of Pluto during theencounter to search for airglow emissions characterize its UVreflectance spectra and to measure the radial distribution of IPMLyα near the disk Our early results suggest that these modelpredictions for the darkening of IPM Lyα with decreasing altitudebeing measureable by Pluto-Alice were correct Well report ourprogress toward extracting H and CH density profiles in Plutosupper atmosphere through comparisons of these data with detailedradiative transfer modeling These New Horizons findings will haveimportant implications for determining the extent of Plutosatmosphere and related constraints to high-altitude verticaltemperature structure and atmospheric escapeThis work was supported by NASAs New Horizons project

Author(s) Kurt D Retherford G Randall Gladstone SAlan Stern Harold A Weaver Leslie A Young Kimberly AEnnico Cathy B Olkin Andy F Cheng Thomas KGreathouse David P Hinson Joshua A Kammer Ivan RLinscott Alex H Parker Joel Wm Parker Wayne R Pryor Eric Schindhelm Kelsi N Singer Andrew J Steffl Darrell FStrobel Michael E Summers Constantine C C Tsang G LenTyler Maarten H Versteeg William W Woods Nathaniel JCunningham Werner CurdtInstitution(s) 1 Central Arizona College 2 George MasonUniversity 3 JHU Applied Physics Laboratory 4 Max PlanckInstitute for Solar System Research 5 NASA Ames ResearchCenter 6 Nebraska Wesleyan University 7 Southwest ResearchInst 8 Stanford University 9 The Johns Hopkins University

10509 ndash Escape of Plutos Atmosphere In SituMeasurements from the Pluto Energetic ParticleSpectrometer Science Investigation (PEPSSI)instrument on New Horizons and RemoteObservations from the Chandra X-ray observatoryThe escape rate of Plutos atmosphere is of significant scientificinterest The Pluto Energetic Particle Spectrometer ScienceInvestigation (PEPSSI) is a compact energy by time-of-flight(TOF) instrument developed to help address this science goalPluto is known to have an atmosphere and pre-encounter modelshave postulated a majority N composition with free escape of upto ~10 moleculessec The expected major ionization productnear Pluto is singly ionized N molecules with pickup energiessufficient to be measured with PEPSSI In the process of measuringthe local energetic particle environment such measurements canalso provide constraints on the local density of Plutos extendedatmosphere which along with plasma measurements from theSolar Wind Around Pluto (SWAP) instrument also on NewHorizons could allow the inference of the strengh and extent ofmass-loading of the solar wind due to Plutos atmosphere Plutosneutral atmosphere also provides a source population for chargeexchange of highly ionized minor ions in the solar wind such as OC and N This process allows these ions to capture one electronand be left in an excited state That state in turn decays with theemission of a low-energy (100 eV to 1 keV) X-ray Observations ofsuch solar wind charge exchange (SWCX) X-rays have been madein the past of the Earths geocorona and Marss extendedatmosphere The award of almost 40 hours of DirectorsDiscretionary Time (DDT) for observing Pluto with the ChandraX-ray observatory near the period of closest approach of NewHorizons to Pluto potentially enabled a remote determination ofPlutos global outgassing rate using the local solar wind flux asmeasured by the SWAP instrument Preliminary anaysis of datareturned from these observations reveal a definite interaction ofPluto with the solar wind but at a lower strength than had beenpredicted This work was supported by NASAs New Horizonsproject

Author(s) Ralph L McNutt Matthew E Hill Carey MLisse Peter Kollmann Fran Bagenal Stamatios M Krimigis David J McComas Heather A Elliott Scott J Wolk Darrell FStrobel Xun Zhu S A Stern H A Weaver L A Young KEnnico C B OlkinInstitution(s) 1 Harvard-Smithsonian Center for Astrophysics2 Johns Hopkins University 3 Johns Hopkins University AppliedPhysics Laboratory 4 Laboratory for Atmospheric and SpacePhysics University of Colorado 5 NASA Ames Research Center 6Southwest Research Institute 7 Southwest Research InstituteBoulder

10510 ndash First Results on Plutos Energetic ParticleEnvironment from the PEPSSI InstrumentThe New Horizons spacecraft flew by Pluto in July 2015 and passedthrough the wakes of Pluto and its largest moon Charon Plutointeracts with the solar wind via the magnetic fields created bycurrents in its ionosphere and the pick-up of charge-exchange ionsescaping from its atmosphere The PEPSSI instrument (PlutoEnergetic Particle Spectrometer Science Investigation) passedthrough this interaction region Closest approach distance to Pluto

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was 11 Pluto radii inside the orbit of Charon PEPSSI measuresintensities of keV to MeV ions and can distinguish ions in the solarwind from ions originating from Pluto Plutorsquos energetic particleenvironment clearly stands out compared to the surrounding solarwind at these heliospheric distances Electrons in the same energyrange as the ions do not show a distinct signature throughout theflyby There is no indication in the particle observations for anintrinsic magnetic field of Pluto We will present an analysis of thedata that is downlinked throughout August and set them intocontext with measurements taken by PEPSSI in Jupiterrsquosmagnetotail in 2007 This work was supported by NASAs NewHorizons project

Author(s) Peter Kollmann M E Hill R McNutt H TSmith J Vandegriff M Kusterer L Brown D K Haggerty C M Lisse H A Elliott D Strobel F Bagenal E Sidrow DJ McComas M Horanyi E Zirnstein S M Krimigis KEnnico L A Young H A Weaver C B Olkin S A SternInstitution(s) 1 Johns Hopkins University 2 Johns HopkinsUniversity Applied Physics Laboratory 3 NASA Ames 4Southwest Research Institute 5 Southwest Research Institute 6University of Colorado Boulder

10511 ndash Photochemistry Ion Chemistry and HazeFormation in Plutorsquos AtmosphereThe detection of ethylene (C H ) and acetylene (C H ) in Plutorsquosatmosphere provides important ground-truth observations forvalidating photochemical models of Plutorsquos atmosphere Theirdetection also confirms the production of precursor chemicalcompounds involved in the formation of tholins which are thoughtto give Plutorsquos surface its reddish color Photochemical modelspredict many other hydrocarbon and nitrile products currentlyundetected which may also be participants in tholin production onPlutorsquos surface or on atmospheric haze particles The observedatmospheric haze layer extending to altitudes of ~140 km abovePlutorsquos surface suggests a global and very robust process ofatmospheric particle nucleation growth and sedimentation ontoPlutorsquos surface The high altitude extent of the haze layer suggeststhat the nucleation process begins above the expected altituderange where hydrocarbons become supersaturated (below ~30 kmaltitude) This situation may be analogous to that in Titanrsquosatmosphere wherein nucleation and aerosol growth is directlyrelated to large negative ion production In the case of Pluto thismeans that nucleation may occur at altitudes as high as 1200 kmaltitude where ionization in Plutorsquos atmosphere peaks In thispaper we discuss these processes and their implications for hazeformation in Plutorsquos atmosphere and its deposition onto Plutorsquossurface This work was supported by NASAs New Horizons project

Author(s) Michael E Summers S A Stern G RandalGladstone Leslie A Young C B Olkin H A Weaver A FCheng D F Strobel K A Ennico J A Kammer A HParker K D Retherford E Schindhelm K N Singer A JSteffl C C Tsang M H Versteeg T K Greathouse I RLinscott L G Tyler W W Woods D P Hinson J WParker J P Renaud M Ewell Cary M LisseInstitution(s) 1 Applied Physics Laboratory 2 George MasonUniv 3 NASA Ames Research Center 4 Southwest ResearchInstitute 5 Stanford University 6 The Johns Hopkins University7 The SETI Institute

10512 ndash A 3D Global climate model of the Plutoatmosphere to interpret New Horizons observationsincluding the N CH and CO cycles and theformation of organic hazesTo interpret New Horizons observations and simulate the Plutoclimate system we have developed a Global Climate Model (GCM)of Plutos atmosphere In addition to a 3D dynamical core whichsolves the equations of meteorology the model takes into accountthe N condensation and sublimation and its thermal anddynamical effects the vertical turbulent mixing the radiativetransfer through methane and carbon monoxide molecularthermal conduction and a detailed surface thermal model withdifferent thermal inertia for various timescales (diurnal seasonal)

The GCM also includes a detailed model of the CH and CO cyclestaking into account their transport by the atmospheric circulationand turbulence as well as their condensation and sublimation onthe surface and in the atmosphere possibly forming methane iceclouds The GCM consistently predicts the 3D methane abundancein the atmosphere which is used as an input for our radiativetransfer calculationBecause of the radiative timescales the surface thermal inertia andthe slow evolution of the methane cycle the model takes morethan 20 years to become insensitive to the assumed atmosphericinitial states We typically start our simulations in 1975 to simulate2015 but remain sensitive to the assumed initial ices distributionand seasonal thermal inertia map The simulated thermal structureand waves can be compared to the New Horizons occultationsmeasurements As observed the longitudinal variability is verylimited for fundamental reasonsIn addition we have developed a 3D model of the formation oforganic hazes within the GCM It includes the different steps ofaerosols formation as understood on Titan photolysis of CH inthe upper atmosphere by the Lyman-alpha radiation production ofvarious gaseous precursor species conversion into solid particlesthrough chemistry and aggregation processes and gravitationalsedimentation Significant amount of haze particles are found to bepresent at all latitudes up to 100 km However if N ice is alreadycondensing in the polar night most of the haze tend to accumulatein the winterfall hemisphere because of the transport of the hazeprecursors and aerosols by the condensation flow

Author(s) Francois Forget Tanguy Bertrand MelanieVangvichith Jeremy LeconteInstitution(s) 1 LMD IPSL CNRS Universiteacute P et M Curie

106 ndash The Asteroid Composition ChannelFrom Soft Rock to Heavy Metal10601 ndash NIR spectral and mineralogic studies of nineVp-type asteroids 7 likely Vestoids and 2 likely newouter belt basaltic asteroid candidatesNine additional Vp-type asteroids as candidate basaltic asteroidswere observed at the NASA Infrared Telescope Facility (IRTF) fromJanuary 15-19 2015 UT as part of a continuing NASA PlanetaryAstronomy Program grant to better characterize the abundance anddistribution of basaltic asteroids in the main asteroid belt TheVp-type asteroids which are classified based on Sloan ugriz colorsand the subsequent coarse visible-wavelength spectra that resultsincludes (2168) Swope (3715) Stohl (3849) Incidentia (5754)1999 FR2 (10666) Feldberg (19165) 1991 CD (34698) 2001 OD22and (36118) 1999 RE135 The first seven of these Vp-type asteroidseither reside near (4) Vesta dynamical space or are located withinthe 31 mean-motion resonance The latter two Vp-type asteroidsare located beyond the 31 mean-motion resonance NIR spectrawere obtained using SpeX in prism mode (07 to 25 microns) at theparallactic angle using the 08 arsec slit Seven of the Vp-typeasteroids were observed on two nights while (2168) Swope wasobserved on three nights and (19165) 1991 CD was observed on asingle night Average near-infrared (NIR) reflectance spectra of theasteroids were analyzed using MATLAB-based (Reddy et al 2011)and IDL-based SARA (Lindsay et al 2013) routines to isolateabsorption features and measure band centers band areas andband depths Temperature corrections were applied to band centersto allow comparison with HED meteorite band parameters Initialresults indicate that all nine asteroids exhibit similar spectral bandcenters and Band Area Ratios (BAR) across different nights withlittle or no significant variation The MATLAB and SARA analysisroutines also produce similar results for all nine asteroids All nineasteroids exhibit BAR values consistent with basaltic achondrites orexhibit larger values beyond the BAR zone as found in Gaffey et al(1993) WISE-derived albedos for these asteroids range from24-50 Initial analysis indicates that the seven inner-belt Vp-typeasteroids are likely Vestoids and are associated with (4) Vesta while(34698) and (36118) are new candidates for outer-belt basalticasteroids

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Author(s) Paul S Hardersen Vishnu Reddy MattNowinski Maggie DievendorfInstitution(s) 1 Planetary Science Institute 2 Univ of NorthDakota

10602 ndash Are near-Earth Vestoids volatile-richasteroidsAsteroids that are linked to carbonaceous chondrite meteoritesexhibit an absorption feature at ~3 microm which is generallyattributed to hydroxyl- andor water-bearing materials Howeverrelatively weaker 3-microm features have been detected on some bodiesthat are not linked to carbonaceous chondrites For these bodiesthe 3-microm feature could be due to surficial OH implanted from solarwind or from emplacement of exogenically sourced carbonaceous(low albedo) material Such emplacement has been seen onasteroid (4) Vesta which was visited by NASArsquos Dawn spacecraftCarbonaceous chondrite impactors have been suggested as thesource of the exogenic low-albedo material on Vesta and the sourceof the event that created the older Veneneia basin on Vestarsquos southpole If the low-albedo material delivered to Vesta during theVeneneia-forming event were mixed with howarditic material toform Vestoids some of which were later transported to Earth-crossing orbits we would expect to detect this carbonaceousmaterial on these near-Earth Vestoids HED meteorites also showcarbonaceous chondrite clasts To test this hypothesis we haveobserved Vestoids in the 3-microm region using the long-wavelengthcross-dispersed (LXD 19ndash42-microm) mode of the SpeXspectrographimager at the NASA Infrared Telescope Facility(IRTF) Here we present high-quality 3-microm spectra of twoNear-Earth Vestoids (357439) 2004 BL which was observedduring close flyby of Earth January 2015 and (4055) Magellanwhich was observed in August 2015 This work has implications forboth the understanding of the origin of Vestoids and thecharacterization of the 3-microm region in spectra of near-EarthasteroidsThis research is supported by the USGS Shoemaker Fellowship andNASArsquos Near-Earth Object Observations Program Parts of thisresearch work was supported by the NASA Near-Earth ObjectObservations Program grant NNX14AL06G (PIReddy) NASAIRTF is operated by the University of Hawaii under CooperativeAgreement No NCC 5-538 with NASA Office of Space SciencePlanetary Astronomy Program

Author(s) Driss Takir Vishnu Reddy Juan A Sanchez Lucille Le Corre Paul S HardersenInstitution(s) 1 Planetary Science Institute 2 US GeologicalSurvey 3 University of North Dakota

10603 ndash Early Evolution of the Main Belt Informed bythe Compositional Diversity of Basaltic AsteroidsWe present near-infrared (078-245 micron) reflectance spectrafor eight outer main belt (a gt 25 AU) asteroids that have beentaxonomically classified as V-types based on visible wavelengthdata Three of these objects are spectrally distinct from allclassifications in the Bus-DeMeo spectral catalogue and thus couldrepresent either spectral end members of the V-type taxonomicclass or a small population of a new spectral type The remainder ofthe sample are classified as V- or R-type All of these asteroids aredynamically distinct from the Vestoid family implying that theyoriginated from differentiated planetesimals which have since beendestroyed or ejected from the solar system The 1- and 2-μm bandcenters of all objects determined using Modified Gaussian Modelfits were compared to those of 47 Vestoids and fifteen HEDmeteorites of known composition Formulas relating Band 1 andBand 2 centers to the pyroxene mineralogies of these asteroidswere derived from the sample of HED meteorites and used todetermine the Fs numbers of all asteroids The Fs numbers of thefive outer belt V- and R-type asteroids are on average between fiveand ten molar percent lower than those of the Vestoids implyingthat these objects formed in a more reducing environment thanVesta Given the complex evolution of oxygen fugacity in the solarnebula these compositional results suggest that these outer beltbasaltic asteroids formed either interior to Vesta and were laterscattered to the outer belt or formed at a later epoch than Vesta

Author(s) Thomas Leith Nicholas Moskovitz RhiannonMayne Francesca DeMeo Driss TakirInstitution(s) 1 Astrogeology Science Center United StatesGeological Survey 2 Lowell Observatory 3 MassachusettsInstitute of Technology 4 Monnig Meteorite Collection TexasChristian University

10604 ndash Finding metal-rich asteroids ndash aNEOShield-2 StudyThe 12 km diameter Barringer Crater in Arizona was produced byan impact of a metallic asteroid whereas the impact of a similarsized stony asteroid in 1908 over Tunguska Russia resulted in alarge airburst but no craterStudies of the metal content of asteroids are relevant not only toestimations of their potential to wreak devastation on impactingthe Earth but also for theories of their origins and nature andpossibly in the future for endeavors in the field of planetaryresourcesHowever the reflection spectra of metallic asteroids are largelyfeatureless which makes it difficult to identify them and relativelyfew are therefore known With reference to radar albedos andtaxonomic classifications we showed (Harris and Drube 2014)that data from the WISENEOWISE thermal-infrared survey(Wright et al 2010 Mainzer et al 2011a) fitted with a simplethermal model (NEATM Harris 1998) can reveal asteroids likelyto be metal rich based on the NEATM fitting parameter η whichcarries information on thermal inertiaTo further explore the dependence of η and thermal inertia ontaxonomic type we are continuing analyses of WISENEOWISEdata and expanding them to include IRAS data (Tedesco et al2002) We are calculating the angle between the spin vector andthe solar direction θ for different sightings of asteroids havingknown spin vectors The η values of objects with high thermalinertia and moderate to high spin rates should depend strongly onθ whereas those with low thermal inertia andor low spin ratesshould not We will present the latest results of our work andprovide a demonstration of its potentialReferencesHarris A W and Drube L 2014 Ap J Letters 785 L4Harris A W 1998 Icarus 131 291Mainzer A et al 2011a ApJ 743156Tedesco E F et al 2002 Astron J 123 1056Wright E L et al 2010 AJ 140 1868AcknowledgementsThe research leading to these results has received funding from theEUs Seventh Framework Programme (FP72007-2013) undergrant agreement no 282703 (NEOShield Project) and the EUrsquosHorizon 2020 Programme under grant agreement no 640351(NEOShield-2 Project)

Author(s) Line Drube Alan W HarrisInstitution(s) 1 German Aerospace Center

10605 ndash Near Earth Asteroid (4015) Wilson-Harrington a Possible Source of Meteorites from thePolana or the Themis FamilyNear-Earth asteroid (4015) Wilson-Harrington is particularlyinteresting for a number of reasons It has displayed cometaryactivity hence its designation as comet 107P and since Wilson-Harrington likely originated in the main asteroid belt (Bottke at al2002a) it could also be called a Main-belt Comet This object hasbeen linked to fireballs capable of producing recoverable meteorites(Campins and Swindle 1998) and it is a potential target ofspacecraft missions We have carried out spectroscopic anddynamical studies of Wilson-Harrington and we narrow its likelyorigin to either the Polana or the Themis asteroid families Wepresent new visible and near-infrared spectra of Wilson-Harrington that show significant similarities with members of theThemis and Polana families These spectral parallels are consistentwith dynamical arguments that connect the current orbit ofWilson-Harrington with each of these two families However it isnot clear at this time which of the families is the more likely originfor Wilson-Harrington Our work also has implications on sourcesof primitive meteorites

2 12 2

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Author(s) Humberto Campins Javier Licandro Julia deLeoacuten Noemiacute Pinilla-Alonso Vania Lorenzi Victor Ali-Lagoa Alessandro MorbidelliInstitution(s) 1 Fundacioacuten Galileo Galilei ndash INAF 2 Institutode Astrofiacutesica de Canarias ndash IAC 3 Laboratoire LagrangeObservatoire de la Cocircte drsquoAzur 4 Univ of Central Florida 5University of Tennessee

10606 ndash 3-microm spectroscopy of Near-Earth AsteroidsSearching for OHH O on small planetary bodiesNear-Earth asteroids (NEAs) are not expected to have OH andorH O ice on their surfaces because a) most accreted dry in theinner Solar System and therefore never contained hydratedmaterials and b) their relatively high surface temperatures shouldquickly drive OHH O off their surface However OHH O hasbeen detected on other anhydrous inner solar system objectsincluding the Moon and Vesta Possible mechanisms to explainOHH O on surfaces in the inner Solar System include productionvia solar wind interactions carbonaceous chondrite or cometaryimpact delivery or native OHH O molecules bound tophyllosilicates As these processes are active in near-Earth spacewe hypothesize that detectable levels of OHH O are present onNEAsThe OHH O feature can be comprised of an OH absorptionfeature centered near 27 μm and H O features near 29 and 31μm or a blend of both producing a relatively wide featurespanning 27 ndash 31 μm Analysis of the shape of the 3-microm featurecoupled with the observed NEA orbital parameters and albedoscan help distinguish between the possible sources of OHH OHere we present results of an ongoing observational program tomeasure spectra of NEAs in the 3-μm region We are using theSpeX instrument on NASArsquos IRTF to measure spectra from ~2 to42 μm So far we have 12 observations of 8 NEAs Of theseobjects three exhibit a 3-μm feature both of our observations of(443) Eros three observations of (1036) Ganymed and (3122)Florence exhibit The NEAs (54789) 2001 MZ7 (96590) 1998 XB(285944) 2001 RZ11 (214088) 2004 JN13 (357439) 2004 BL86do not exhibit a feature Rivkin et al (2013 LPSC) has alsoreported detections of the 3-μm feature on Ganymed and Eros withdata taken in the same year as ours (2012) Band shape albedoand orbital analysis of the NEAs exhibiting the 3-microm featureindicate that the primary production mechanism of OHH O onEros and Ganymed is solar wind interactions For Florence on theother hand it appears that in-fall of carbonaceous material mightbe the primary mechanism We will discuss the implications ofthese results for potential sources of OHH O on the surfaces ofNEAs in general and prospects for future observations

Author(s) Nathanael Wigton Joshua Emery CristinaThomas Andy RivkinInstitution(s) 1 JHUAPL 2 Planetary Science Institute 3University of Tennessee

10607 ndash Euphrosyne As An NEO Source SpectralProperties and Inferences from MeteoritesThe Euphrosyne family is interpreted as ejecta from an impact into31 Euphrosyne a large C-class asteroid in the outer part of themain belt Recent work by Masiero et al suggests that Euphrosynefamily members may preferentially find their way into the NEOpopulation and presumably from there into the meteoritecollections of the worldInterestingly observations of Euphrosyne in the 3-microm spectralregion by Takir et al and Rivkin et al show it to have a roundedband shape and a band center near 31 microm Such a band shape hasnever been seen in any meteorite spectra collected to date butthese characteristics are reminiscent of 24 Themis and 65 Cybelewhose spectra have been interpreted as having bands due to icefrost and organic materials The spectra of Euphrosyne familyobjects and those NEOs thought to have originated in that familytherefore may show how icy objects evolve as they move from theasteroid belt to orbits near 1 AU and how they may (or may not) berepresented in the meteorite record Alternately they may give riseto new interpretations of the absorptions that have not yet beenconsidered

We will discuss the combined implications of Euphrosynersquosspectrum and family dynamics and the opportunities for betterunderstanding the nature of outer belt asteroids that observationsof the Euphrosyne family provide

Author(s) Andrew S Rivkin Lucy F Lim Joshua PEmeryInstitution(s) 1 JHUAPL 2 NASA GSFC 3 University ofTennessee

10608 ndash SOFIA observations of dark asteroidsEvidence for hydrated minerals on asteroidalsurfacesWe present results from recent SOFIA+FORCAST observations ofthree primitive asteroids and compare these to archived SpitzerSpace Telescope (Spitzer) observations of similar objects Threeasteroids from a total of 12 have been observed withSOFIA+FORCAST in our Cycle-3 campaign Currently we haveobserved asteroids 38 Leda 194 Prokne with both G111 and G227grisms and asteroid 266 Aline with G227 Both wavelength regions(G111 85-135-μm and G227 176-277) have recently been shownto contain spectral features directly related degree of alteration ofprimitive meteorites including unaltered CO and CV meteorites(McAdam et al 2015a b) Spectral features in the 176-277-μmregion can be indicative of olivine (195-μm) hydrated minerals(21-μm) and silica glass (22-μm) Spitzer observed eight largeprimitive main-belt asteroids using both low-resolution modes(short-low SL and long-low LL) of the Infrared Spectrograph(IRS) covering 85-38-μm Additionally Spitzer observed 22 darkprimitive asteroids in the 85-135-μm region Asteroids observedwith Spitzer fall into three categories asteroids with a 12-μmfeature of 1-5 depth interpreted as ~60-70 hydrated minerals(McAdam et al 2015a) asteroids with a broader 12-13-μm featurewith strengths ranging from 4-6 with potential features between19-22-μm (where observed) and asteroids with a strong 13-μmfeature (5-10) 15-μm and potentially 19-22-μm features (whereobserved) interpreted as olivine-rich However the uncertaincalibration at the edges of the LL spectral orders complicatesfeature identification 194 Prokne has a feature ~12-13-μm featureand potentially a broad feature between 20-22-μm This isconsistent with primitive asteroids observed with Spitzer that areinterpreted as hydrated mineral-bearing 38 Leda is largelyfeatureless at the noise limit of the spectrum with a potentialfeature at 25-μm unlike asteroids observed by Spitzer 266 Alinehas a weak feature at 225-μm and is potentially similar to thoseasteroids observed with both modes that are hydrated-mineralbearingMcAdam et al (2015a) Icarus 245 320-332McAdam et al (2015b) LPSC abstract 2540

Author(s) Margaret McAdam Jessica M Sunshine MichaelS P T KelleyInstitution(s) 1 University of Maryland

10609 ndash PRIMitive Asteroids Spectroscopic Survey ndashPRIMASS First ResultsNASA OSIRIS-REx and JAXA Hayabusa 2 sample-return missionshave targeted two near-Earth asteroids (101955) Bennu and(162173) 1999 JU3 respectively These are primitive asteroids thatare believed to originate in the inner belt where five distinctsources have been identified four primitive collisional families(Polana Erigone Sulamitis and Clarissa) and a population oflow-albedo and low-inclination background asteroids Identifyingand characterizing the populations from which these two NEAsmight originate will enchance the science return of the twomissionsWith this main objective in mind we initiated in 2010 aspectroscopic survey in the visible and the near-infrared tocharacterize the primitive collisional families in the inner belt andthe low-albedo background population This is the PRIMitiveAsteroids Spectroscopic Survey ndash PRIMASS So far we haveobtained more than 200 spectra using telescopes located atdifferent observatories PRIMASS uses a variety of ground basedfacilities Most of the spectra have been obtained using the 104m

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Gran Telescopio Canarias (GTC) and the 36m TelescopioNazionale Galileo (TNG) both located at the El Roque de losMuchachos Observatory (La Palma Spain) and the 30m NASAInfrared Telescope Facility on Mauna Kea (Hawai USA)We present the first results from our on-going survey (de Leon etal 2015 Pinilla-Alonso et al 2015 Morate et al 2015) focused onthe Polana and the Erigone primitive families with visible andnear-infrared spectra of more than 200 objects most of them withno previous spectroscopic data Our survey is already the largestdatabase of primitive asteroids spectra and we keep obtaining dataon the Sulamitis and the Clarissa families as well as on thebackground low-albedo population

Author(s) Julia de Leon Noemi Pinilla-Alonso HumbertoCampins Vania Lorenzi Javier Licandro David Morate PaoloTanga Alberto Cellino Marco DelboInstitution(s) 1 Fundacion Galileo Galilei - INAF 2 INAFOsservatorio Astrofisico di Torino 3 Instituto de Astrofisica deCanarias 4 Laboratoire Lagrange Observatoire de la Cocircte drsquoAzur5 University of Central Florida Physics Department 6 Universityof Tennessee Department of Earth and Planetary Sciences

10610 ndash 5 ndash 14 μm Spitzer spectra of primitiveasteroid familiesCompositional studies of primitive asteroid families provideconstraints on the physical and chemical environment of the solarnebula and the evolution of the asteroid belt Spectroscopic studiesin the visible and near-infrared have shown spectral diversitybetween primitive families Our goal is to better constrain thecomposition of two primitive families with very different agesThemis (~25 Gyr) and Veritas (~8 Myr) We analyzed 5 ndash 14 μmSpitzer Space Telescope spectra of a total of 18 asteroids nine fromeach family We report the presence of a broad 10-μm emissionfeature attributed to a layer of fine-grained silicates in the spectraof all nine Themis asteroids and six of nine Veritas asteroids in oursample Spectral contrast in statistically significant detections of the10-μm feature ranges from 1 plusmn 01 to 85 plusmn 09 Comparisonwith the spectra of primitive meteorites (McAdam et al 2015Icarus 245 320) suggests asteroids in both families are similar tometeorites with lower abundances of phyllosilicates We used theNear-Earth Asteroid Thermal Model to derive diameters beamingparameters and albedos for our sample Asteroids in both familieshave beaming parameters near unity and geometric albedos in therange 006 plusmn 001 to 014 plusmn 002 We find that contrast of thesilicate emission feature is not correlated with asteroid diameterhowever higher 10-μm contrast may be associated with flatterspectral slopes in the near-infrared The spectra of both familiessuggest icy bodies with some amount of fine-grained silicates butwith coarser grains or denser surface structure than Trojanasteroids and comets

Author(s) Zoe A Landsman Javier Licandro HumbertoCampins Julie Ziffer Maacuterio de PraacuteInstitution(s) 1 Instituto de Astrofiacutesica de Canarias 2Observatoacuterio Nacional 3 University of Central Florida 4University of Southern Maine

10611 ndash Compositional study of the Themis familyThemis is an outer main-belt family comprising more than 4000dynamically well-established members (Nesvorny 2012) mainly B-and C-type asteroids (Florczak et al 1999 Motheacute-Diniz et al 2005Ziffer et al 2011) This family is rather unique for a number ofreasons- It is believed to be the only main-belt family formed from thecatastrophic disruption of a large (Dgt200 km) B-C-type body(Brož et al 2013) As such it offers a unique view on the internalcomposition of a primitive asteroid- Elst-Pizarro one of the family member was one of the first mainbelt comets to be discovered (Hsieh amp Jewitt 2006)- 24 Themis is the first main belt asteroid for which water ice wasdetected at its surface (Campins et al 2010 Rivkin amp Emery 2010)- The low density values recorded for two family members (lt13gcm3 Descamps et al 2007 Marchis et al 2008) likely implyhigh fractions of ice(s) in the interior of these bodies

The last three features all point towards an ice-rich composition forthe Themis parent body while showing little compatibility with athermally metamorphosed body that has been heated throughoutat temperatures exceeding 300 K The latter interpretation waspreviously suggested on the basis of a similarity between thenear-infrared spectral properties of heated CICM chondrites andthose of the family membersrsquo surfaces (Clark et al 2010 Ziffer etal 2011) In brief the Themis family members appear unsampledby our meteorite collections Recently Vernazza et al (2015)instead proposed that Interplanetary Dust Particles (IDPs) may bemore appropriate extraterrestrial analogs for these objectsrsquosurfacesIn the light of Vernazza et al (2015)rsquos recent work we investigatedthe surface mineralogy of a sample of Themis family membersusing a combined dataset of spectra covering the visible (Bus ampBinzel 2002 Lazzaro et al 2004) near-infrared (this work) andmid-infrared (Licandro et al 2012 Hargrove et al 2015) spectralrangesAssuming particle sizes (typically sub- to micrometer sizes) andend-members composition similar to those found in chondriticporous IDPs we modeled the spectral properties of the Themisfamily members The results of this study will be presented indetails

Author(s) Michael Marsset Pierre Vernazza Mirel Birlan Francesca DeMeo Richard P Binzel Christophe Dumas JulienMilli Marcel PopescuInstitution(s) 1 Astronomical Institute of the RomanianAcademy 2 European Southern Observatory 3 Institut deMeacutecanique Ceacuteleste et de Calcul des Epheacutemeacuterides 4 LaboratoiredAstrophysique de Marseille 5 Massachusetts Institute ofTechnology

10612 ndash Interplanetary Dust Particles As Samples ofIcy AsteroidsMeteorites have long been considered as reflections of thecompositional diversity of main belt asteroids and consequentlythey have been used to decipher their origin formation andevolution However while some meteorites are known to samplethe surfaces of metallic rocky and hydrated asteroids (aboutone-third of the mass of the belt) the low-density icy asteroids (C-P- and D-types) representing the rest of the main belt appear tobe unsampled in our meteorite collections Here we provideconclusive evidence that the surface compositions of these icybodies are compatible with those of the most commonextraterrestrial materials (by mass) namely anhydrousinterplanetary dust particles (IDPs) Given that these particles arequite different from known meteorites it follows that thecomposition of the asteroid belt consists largely of more friablematerial not well represented by the cohesive meteorites in ourcollections In the light of our current understanding of the earlydynamical evolution of the solar system meteorites likely samplebodies formed in the inner region of the solar system (05ndash4 AU)whereas chondritic porous IDPs sample bodies that formed in theouter region (gt5 AU)

Author(s) Pierre Vernazza Michael Marsset Pierre Beck Richard Binzel Mirel Birlan Rosario Brunetto FrancescaDeMeo Zahia Djouadi Christophe Dumas Sihane Merouane Olivier Mousis Brigitte ZandaInstitution(s) 1 ESO 2 IAS 3 IMCCE 4 IPAG 5 LaboratoiredAstrophysique de Marseille 6 MIT 7 MNHN 8 MPS

107 ndash Mercury and the Moon10701 ndash Mercuryrsquos exosphere New detectionsdiscoveries and insightsFor over 16 Mercury years the MESSENGER spacecraft orbited theplanet Mercury and conducted a variety of observations of theexosphere Part of the overall observing plan was a search forexospheric species that are less abundant andor more weaklyemitting than the more easily observed Na Ca and Mg For mostof the orbital phase this search has resulted in nothing more than

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increasingly refined upper limits However in the last few Mercuryyears three species that had eluded this programmatic search wereobserved Emission from multiple lines of Ca was detectedvalidating the observation of a single line of Ca during the thirdMESSENGER Mercury flyby Multiple lines of Al were alsodetected providing definitive evidence for a species that has beensuggested from ground-based observations Finally emission fromMn has been discovered adding another member to the pantheonof exospheric species All these detections were somewhat localizedabout the planet and during the Mercury year Equally interestingas these observations is absence of detectable emission from otherspecies such as O We will report on both the detections andnon-detections provide altitude profiles where possible anddiscuss the insights gained from these species in the context of theoverall exosphere The NASA MESSENGER Participating ScientistProgram supported this work

Author(s) Ronald J Vervack Jr William E McClintock Rosemary M Killen Aimee W Merkel Matthew H Burger Menelaos Sarantos Timothy A CassidyInstitution(s) 1 GSFC 2 JHUApplied Physics Laboratory 3Morgan State UniversityGESTAR 4 UMBC 5 University ofColorado

10702 ndash A seasonal feature in Mercuryrsquos exospherecaused by meteoroids from comet EnckeThe planet Mercury is enveloped in a tenuous atmosphere theresult of a delicate balance between poorly understood sources andsinks (Killen et al 2007) Meteoroid impacts are a contributingsource process (eg Wurz et al 2010) but their importancecompared to other production mechanisms is uncertainKillen and Hahn (2015) found that seasonal variations inMercurys calcium exosphere as observed by Mercury Atmosphericand Surface Composition Spectrometer (MASCS) onboard theMErcury Surface Space ENvironment GEochemistry andRanging (MESSENGER) spacecraft (Burger et al 2014) may beattributed to impact vaporization of surface material by the infall ofinterplanetary dust However an additional dust source wasrequired to explain a Ca excess at a True Anomaly Angle (TAA) of25plusmn5 deg Killen and Hahn suggested that dust from comet2PEncke crossing Mercurys orbital plane at TAA=45 deg may bethe culpritWe have simulated numerically the stream of meteoroids ejectedfrom Encke in order to identify those particles that impact Mercuryat the present epoch and test the Killen and Hahn conjecture Wefind that Encke particles evolving solely under the gravity of themajor planets and the Sun encounter Mercury at TAA=50-60 degwell after the peak of the Ca excess emission This result isindependent of the time of ejection However the addition ofPoynting-Robertson (P-R) drag in our model couples the age andsize of the meteoroids to the TAA at encounter causing smallerolder particles to encounter Mercury progressively earlier in theHermean year In particular mm-sized grains ejected between 10and 20 kyr ago impact on the nightside hemisphere of Mercury atTAA = 350minus30 deg near the observed peak time of the exosphericfeatureDuring this presentation we will describe our model results anddiscuss their implications for the physical mechanism that injectsimpact-liberated Ca into sunlight as well as the origin and evolutionof the Encke stream of meteoroidsAstronomical Research at Armagh Observatory is funded by theNorthern Ireland Department of Culture Arts and Leisure (DCAL)

Author(s) Apostolos Christou Rosemary M Killen Matthew H BurgerInstitution(s) 1 Armagh Obs 2 Goddard Earth SciencesTechnology and Research Morgan State University 3 NASAGoddard Space Flight Center

10703 ndash Solar Wind Charge Exchange X-ray emissionfrom Mercuryrsquos exosphere Detectability with BepiColomborsquos MIXS spectrometerWe have conducted preliminary hybrid simulations to calculate theSolar Wind Charge Exchange (SWCX) X-ray emission in Mercuryrsquos

exosphere Our results imply that the OVII triplet emissionintensity for standard slow solar wind conditions is of the sameorder as the one predicted by simulations for Mars and measuredby Chandra in past observations of Mars Using an oversimplifieddetector and observation geometry we explore the detectability ofMercurys SWCX emission by the MIXS spectrometer on boardBepi Colomborsquos planetary orbiter (MPO)

Author(s) Dimitra Koutroumpa Konrad Dennerl FranccediloisLeblanc Ronan ModoloInstitution(s) 1 LATMOS-CNRS 2 MPE

10704 ndash Mercuryrsquos EUV Reflectance Spectrum FromMariner 10 RevisitedCarbon as graphite has emerged from recent analyses ofMESSENGER spectrophotometry and theoretical modeling as apossible source for the darkening component in the LowReflectance Material (LRM) pervasive across Mercuryrsquos surfaceMurchie et al (Icarus 254 287 2015) propose graphite inamounts consistent with results from MESSENGERrsquos elementalexperiments for the presence of C as the most likely darkeningcomponent in LRM Vander Kaaden and McCubbin (JGR Planets120 195 2015) report that graphite would be the only buoyantphase in an early magma ocean and any primary flotation crustwould have retained C in the form of graphite AlternativelyGillis-Davis et al (Abstract P1 1A-07 AGU 2013) suggest thatnanophase and microphase iron produced by impacts intoMercuryrsquos crust before and during the late heavy bombardmentcould darken the LRM Carbon in the forms of graphite andanthracite has distinctive far-UV spectral reflectance features TheMESSENGER MASCS UVVS spectrometer does not extend towavelengths short enough to observe these features The Mariner10 EUV airglow spectrometer observed broad swaths of Mercury in10 filters at wavelengths ranging from 304Aring to 1657Aring each having20Aring passbands We now re-analyze these data in a search for thisdistinctive UV signature of graphite across large areas of Mercuryrsquossurface and will report on the results

Author(s) Faith Vilas Amanda R Hendrix Elizabeth AJensenInstitution(s) 1 Planetary Science Institute

10705 ndash Mercuryrsquos gravity field tidal Love number k2and spin axis orientation revealed with MESSENGERradio tracking dataWe are conducting an independent analysis of two-way Dopplerand two-way range radio tracking data from the MESSENGERspacecraft in orbit around Mercury from 2011 to 2015 Our goalsare to estimate Mercuryrsquos gravity field and to obtain independentestimates of the tidal Love number k2 and spin axis orientationOur gravity field solution reproduces existing values with highfidelity and prospects for recovery of the other quantities areexcellentThe tidal Love number k2 provides powerful constraints on interiormodels of Mercury including the mechanical properties of themantle and the possibility of a solid FeS layer at the top of the coreCurrent gravity analyses cannot rule out a wide range of values(k2=43ndash050) and a variety of plausible interior models We areseeking an independent estimate of tidal Love number k2 withimproved errors to further constrain these modelsExisting gravity-based solutions for Mercurys spin axis orientationdiffer from those of Earth-based radar and topography-basedsolutions This difference may indicate an error in one of thedeterminations or a real difference between the orientations aboutwhich the gravity field and the crust rotate which can exist in avariety of plausible configuration Securing an independentestimate of the spin axis orientation is vital because this quantityhas a profound impact on the determination of the moment ofinertia and interior modelsWe have derived a spherical harmonic solution of the gravity fieldto degree and order 40 as well as estimates of the tidal Lovenumber k2 and spin axis orientation

++

2 51 5 3

4 5

1 32

1 21 1

1 11

20

Author(s) Ashok Kumar Verma Jean-Luc MargotInstitution(s) 1 UCLA

10706 ndash Perpetual long libration of terrestrial planetsin tidal resonancesOn the example of Mercury I show that firm planets of terrestrialcomposition locked in the 32 or higher spin-orbit resonancesundergo long-period perpetual libration in longitude without anyinfluence of third bodies This non-damped libration at the naturalfrequency is driven by a secular tidal torque which is increasingwith frequency within a narrow interval around the resonance Thespectrum of regular forced eccentricity-driven libration definesthe conditions for the perpetual long libration The possibility ofvalidating the tidal theory from the observable amplitude ofperpetual libration is discussed

Author(s) Valeri MakarovInstitution(s) 1 US Naval Observatory

10707 ndash The Lunar Profile and Bailys Beads at SolarEclipsesThe lunar mapping from NASAs Lunar Reconaissance Orbiter andJAXAs Kaguya has provided information that allows calculation ofthe lunar limb profile whose low points at total solar eclipsesprovides the Bailys Beads Preparations for the forthcomingAugust 21 2017 total solar eclipse (lunar occultation) whosetotality crosses the continental United States from northwest tosoutheast (httpeclipsesinfo for the International AstronomicalUnion Working Group on Solar Eclipses) has led to newcalculations of the Bailys Beads and of comparisons of the totalityduration between predictions and observations for historicaleventsJMPs research on the annular and total solar eclipses of 2012 wassupported in part by the SolarndashTerrestrial Program of theAtmospheric and Geospace Sciences Division of the NationalScience Foundation through grant AGSndash1047726 His observationsof the 2013 and 2015 total solar eclipses were supported by grants9327-13 and 9616-14 respectively from the Committee forResearch and Exploration of the National Geographic Society withadditional support from Williams College

Author(s) Jay M Pasachoff Ernest T WrightInstitution(s) 1 NASAs GSFC 2 Williams College

10708 ndash Transitional lava flows as potentialanalogues for lunar impact meltsLunar impact melt deposits are among the roughest surfacematerials on the Moon at the decimeter scale even though theyappear smooth at the meter scale These characteristics distinguishthem from well-studied terrestrial analogues such as Hawaiianpāhoehoe and ʻaʻā lava flows The morphology of impact meltdeposits can be related to their emplacement conditions sounderstanding the origin of these unique surface properties willinform us as to the circumstances under which they were formedAlthough there is no perfect archetype for lunar impact melts onEarth certain terrestrial environments lend themselves asfunctional analogues Specifically a variety of transitional lava flowtypes develop if the surface of a pāhoehoe-like flow is disruptedproducing lsquoslabbyrsquo or lsquorubblyrsquo flows that are extremely rough at thedecimeter scale We investigated the surface roughness oftransitional lava flows at Craters of the Moon (COTM) NationalMonument comparing radar imagery and high-resolutiontopographic profiles to similar data sets acquired by the LunarReconnaissance Orbiter for impact melt deposits on the MoonResults suggest that the lava flows at COTM have similar radarproperties to lunar impact melt deposits but the terrestrial flowsare considerably rougher at the meter scale It may be that lunarimpact melts represent a unique lava type not observed on Earthwhose surface texture is influenced by their high emplacementtemperatures andor cooling in a vacuum Information about thesurface properties of lunar impact melt deposits will be critical forfuture landed missions that wish to sample these materials

Author(s) Catherine Neish Scott Hughes ChristopherHamilton Shannon Kobs Nawotniak William Brent Garry John Roma Skok Richard Elphic Lynn Carter JoshuaBandfield Gordon Osinski Darlene Lim Jennifer HeldmannInstitution(s) 1 Idaho State University 2 NASA Ames ResearchCenter 3 NASA GSFC 4 SETI Institute 5 Space Science Institute6 The University of Arizona 7 The University of Western Ontario

10709 ndash The Effect of Pre-Impact Porosity andVertical Density Gradients on the Gravity Signature ofLunar CratersAs a result of NASArsquos dual spacecraft Gravity Recovery And InteriorLaboratory (GRAIL) mission [Zuber et al 2013doi101126science1231507] we now know that the lunar crust ishighly porous and that the porosity varies laterally [Wieczorek etal 2013 doi101126science1231530] and vertically [Besserer etal 2014 doi1010022014GL060240] Analysis of complexcraters located within the lunar highlands reveals that 1) craterslarger than diameter D~210 have positive Bouguer Anomalies(BAs) 2) craters with D ≲ 100 km have both positive and negativeBAs that vary about the (near 0) mean by approximately plusmn 25mGal and 3) D and BA are anticorrelated for craters with D ≲ 100km [Soderblom et al 2015 doi1010022015GL065022]Numerical modeling by Milbury et al [2015 LPSC] shows thatpre-impact porosity is the dominant influence on the gravitysignature of complex craters with D ≲ 100 km and mantle upliftdominates the gravity for those with D gt 140 km Phillips et al[2015 LPSC] showed that complex craters located in the SouthPole-Aitken (SPA) basin tend to have more-negative BAs thansimilar craters in the highlands We use the iSALE hydrocodeincluding pore space compaction [Wuumlnnemann et al 2006doi101016jicarus200510013] and dilatant bulking [Collins2014 doi1010022014JE004708] to understand how the gravitysignature of impact craters develop In this study we vary crustalporosity with depth We find that simulations that have constantporosity with depth have a lower BA for a given crater diameterthan those with the same mean porosity but that vary with depthWe used two different mean porosities (7 and 14) and foundthat the BA increases with increasing porosity similar tosimulations with constant porosity We reproduce the observedanticorrelation between BA and D for D ≲ 100 km only forsimulations where the pre-impact porosity is zero or low Ourresults support the observation that SPA has lower overall porositybut higher vertical gradients giving craters within SPAmore-negative BAs than those within the highlands crust Thesesimulations demonstrate that the BA and porosities reported hereare valid for determining general trends only

Author(s) Colleen Milbury Brandon C Johnson H JayMelosh Gareth S Collins David M Blair Jason MSoderblom Francis Nimmo Roger J Phillips Carver JBierson Maria T ZuberInstitution(s) 1 Imperial College London 2 MassachusettsInstitute of Technology 3 Purdue University 4 SouthwestResearch Institude 5 UC Santa Cruz

10710 ndash Simulated Water Delivery to LunarPermanently Shadowed RegionsA set of Monte Carlo simulations was run to examine waterdiffusion across the lunar surface and specifically to thePermanently Shadowed Regions (PSRs) This work extends theresults of Schorghofer (2014) to latitudes above 5ordm from the poleand to specific PSRs and is accomplished using a separately derivedmodel to independently test Schorghoferrsquos (2014) results Themodel was validated using the results of Schorghofer (2014) at the5ordm latitude line replicating all of the behaviors of that model butwith slightly different values for the total number of tracer particlesarriving and their fractionation25 times fewer particles were able to survive to arrive within 1ordm ofthe pole as compared to those that were able to arrive within 5ordm ofthe pole For the PSRs themselves 187 of particles wereeventually sequestered within the PSRs by the end of oursimulations Examining the amount of water which could betransported over geological time reveals that sufficient water moves

1 1

1

2 1

7 16 1 3

4 2 35 7 2 2

3 23 1 2

2 5 45 2

21

via migration to (1) supply the hydrogen signals observed by LEND(Mitrofanov et al 2012) (2) the frost at Haworth Crater(Gladstone et al 2012) as well as to explain (3) the high level ofwater seen in the soils of Cabeus Crater in the LCROSS experiment(Colaprete et al 2010) without the need to invoke another watersupply mechanismIn all cases the average time required for migration was small withaverage arrival times of less than a lunar day following an impactSubstantial differences were observed in the amount of wateraccreted by the different PSRs with Cabeus Crater accreting by farthe most water per square meter Faustini and the HaworthLowlands have the next highest delivery receiving ~60 each asmuch water as Cabeus per square meter Shackleton has the lowestwater delivery receiving only ~5 as much water per square meteras Cabeus The simulated results show a clear latitudinal trend withmore water emplaced at lower latitudes Yet the data show verylittle difference between the PSRs in terms of the amount offractionation taking place and low levels of fractionation overallconsidering 1001 distillation between the impactor and the PSRs

Author(s) John MooresInstitution(s) 1 York University

10711 ndash The Influence of Surface Roughness onVolatile Transport on the MoonThe Moon and other virtually airless bodies provide distinctiveenvironments for the transport and sequestration of water andother volatiles delivered to their surfaces by various sources Herewe conduct numerical simulations to investigate the delivery ofwater to the Moon through comet impacts focusing on the role ofsmall-scale topography (ie surface roughness unresolved byorbital measurements) in the migration and cold-trapping ofimpact-delivered water The simulated comet impact generates atransient collisonally thick water vapor atmosphere that surroundsthe Moon for at least several lunar days During this time somewater is captured by permanently shadowed craters (cold traps)near the lunar poles where temperatures are sufficiently low thatvolatiles can remain sequestered over geological time scalesSurface temperature is a critical parameter that determines theresidence time of a migrating water molecule on the lunar surfacethereby affecting the rapidity of volatile transport though pressure-driven winds the susceptibility of migrating molecules to photo-destruction and the large-scale structure of the impact-generatedatmosphere - all of which ultimately affect the rate and magnitudeof cold-trapping The roughness of the lunar surface at smallscales the insulating nature of the lunar regolith and the absenceof strong convective heat transport lead to sharp surfacetemperature gradients surfaces separated by only a fewmillimeters can have dramatically different temperaturesSignificantly small-scale roughness gives rise to cold temporaryand permanent shadows that may affect the rate at which watermigrates to permanent cold traps near the lunar poles and to thetemporary shelter of the cold lunar night side Here we develop asurface roughnesstemperature model consistent with observedbolometric brightness temperature at larger scales suitable forsimulations of volatile transport on a global scale We will present acomparison of results from impact-generated atmospheresimulations with and without the surface roughness model in orderto understand how small-scale roughness influences transientdeposition patterns and the rate and magnitude of cold trapcapture

Author(s) Parvathy Prem Natalia A Artemieva David BGoldstein Philip L Varghese Laurence M TraftonInstitution(s) 1 Planetary Science Institute 2 The University ofTexas at Austin

10712 ndash LRO-LAMP Observations of Lunar ExosphericHeliumWe present results from Lunar Reconnaissance Orbiterrsquos (LRO)UV spectrograph LAMP (Lyman-Alpha Mapping Project) campaignto study the lunar atmosphere Two kinds of off-nadir maneuvers(lateral rolls and pitches towards and opposite the direction ofmotion of LRO) were performed to search for resonantly scattering

species increasing the illuminated line-of-sight (and hence thesignal from atoms resonantly scattering the solar photons)compared to previously reported LAMP ldquotwilight observationsrdquo[Cook amp Stern 2014] Helium was the only elementdistinguishable on a daily basis and we present latitudinal profilesof its line-of-sight column density in December 2013 Wecompared the helium line-of-sight column densities with solarwind alpha particle fluxes measured from the ARTEMIS(Acceleration Reconnection Turbulence amp Electrodynamics ofMoonrsquos Interaction with the Sun) twin spacecraft Our data show acorrelation with the solar wind alpha particle flux confirming thatthe solar wind is the main source of the lunar helium but not witha 11 relationship Assuming that the lunar soil is saturated withhelium atoms our results suggest that not all of the incident alphaparticles are converted to thermalized helium allowing for anon-negligible fraction (~50 ) to escape as suprathermal heliumor simply backscattered from the lunar surface We also supportthe finding by Benna et al [2015] and Hurley et al [2015] that anon-zero contribution from endogenic helium coming fromradioactive decay of Th and U within the mantle is presentand is estimated to be (45plusmn12) x 10 He atoms cm s Finallywe compare LAMP-derived helium surface density with the onerecorded by the mass spectrometer LACE (Lunar AtmosphericComposition Experiment) deployed on the lunar surface during theApollo 17 mission finding good agreement between the twomeasurements These LRO off-nadir maneuvers allow LAMP toprovide unique coverage of local solar time and latitude of the lunarexospheric helium allowing for a better understanding of thetemporal and spatial structure of the lunar exosphere

Author(s) Cesare Grava Kurt D Retherford Dana MHurley Paul D Feldman Randy Gladstone Thomas KGreathouse Jason C Cook Alan Stern Wayne R Pryor Jasper S Halekas David E KaufmannInstitution(s) 1 Central Arizona College 2 Johns HopkinsUniversity 3 Johns Hopkins University - Applied PhysicsLaboratory 4 Southwest Research Institute 5 University of Iowa

200 ndash Pluto System IV--Saving the Best forLast20001 ndash Configuration of Plutos Volatile IcesWe report on near-infrared remote sensing by New HorizonsRalph instrument (Reuter et al 2008 Space Sci Rev 140129-154) of Plutos N CO and CH ices These especially volatileices are mobile even at Plutos cryogenic surface temperaturesSunlight reflected from these ices becomes imprinted with theircharacteristic spectral absorption bands The detailed appearanceof these absorption features depends on many aspects of localcomposition thermodynamic state and texture Multiple-scattering radiative transfer models are used to retrievequantitative information about these properties and to map howthey vary across Plutos surface Using parameter maps derivedfrom New Horizons observations we investigate the strikingregional differences in the abundances and scattering properties ofPlutos volatile ices Comparing these spatial patterns with theunderlying geology provides valuable constraints on processesactively modifying the planets surface over a variety of spatialscales ranging from global latitudinal patterns to more regional andlocal processes within and around the feature informally known asSputnik Planum This work was supported by the NASA NewHorizons Project

1

2 12 2 2

232 2386 -2 -1

4 43 2 4

4 4 4 15 4

2 4

22

Author(s) William M Grundy R P Binzel J C Cook D PCruikshank C M Dalle Ore A M Earle K Ennico D EJennings C JA Howett I R Linscott A W Lunsford C BOlkin A H Parker J Wm Parker S Protopapa D C Reuter KN Singer J R Spencer S A Stern C CC Tsang A JVerbiscer H A Weaver L A Young K Berry M W Buie J AStansberryInstitution(s) 1 Johns Hopkins University Applied PhysicsLaboratory 2 Lowell Obs 3 Massachusetts Institute ofTechnology 4 NASA Ames Research Center 5 NASA GoddardSpace Flight Center 6 Southwest Research Institute 7 SpaceTelescope Science Institute 8 Stanford University 9 University ofMaryland 10 University of Virginia 11 USGS Astrogeology

20002 ndash The Search for Pluto WaterOn July 14 2015 the New Horizons spacecraft made its closestapproach to Pluto at about ~12000 km from Plutos surface TheLEISA (Linear Etalon Imaging Spectral Array) component of theRalph instrument (Reuter DC Stern SA Scherrer J et al2008 Space Sci Rev 140 129) obtained spatially resolved nearinfrared spectra at scales as small as 3 kmpix LEISA covers thewavelength range 125 to 25 μm at a spectral resolution (λΔλ) of240 and the 21 to 225 μm range at a resolution of 560 Theobservations from this instrument are being used to map thedistribution of Plutos known ices such as N CH CO and C Has well as search for H O-ice To date H O-ice has evadeddetection from Earth bound observatories Observations based onLORRI the LOng Range Reconnaissance Imager suggest H O-iceis a major component of several mountain ranges around thewestern perimeter of the landmass informally named TombaughRegio If true H O-ice may be found in small isolated regionsaround Pluto We will present our analysis of all LESIA data ofPluto in hand to search for and understand the distribution ofH O-ice If found we will also discuss limits on crystalline vsamorphous H O-ice and temperature measurements based on the165 microm crystalline H O-ice feature This work was supported byNASAs New Horizons project

Author(s) Jason C Cook Dale P Cruikshank Cristina MDalle Ore Kimberly Ennico William M Grundy Cathy BOlkin Silvia Protopapa S Alan Stern Harold A Weaver Leslie A YoungInstitution(s) 1 John Hopkins University Applied PhysicsLaboratory 2 Lowell Observatory 3 NASA Ames ResearchCenter 4 SETI Institute 5 Southwest Research Institute 6University of Maryland

20003 ndash New Horizons data in the context of priorobservationsThe New Horizons encounter data have revealed a diverse andcomplicated surface and atmosphere for Pluto showing strongcorrelations between geologic features and the albedo andcompositional units known from ground- and HST-basedobservations over the decades prior This presentation makedetailed comparisons between the long time base and low spatialresolution data and the new high resolution stanpshot of Plutofrom the flyby Special emphasis will be placed on the albedoevolution over time with some attention paid to near-infraredspectral signatures We will compare the albedo maps from mutualevent data and two epochs of HST observations against the NewHorizons images after correcting for viewing geometry Alsoincluded will be a discussion of the evolutionary trends in thehemispherically averaged spectral properties from LowellObservatory and IRTF data against the resolved compositional andspectral maps from New Horizons The combination of these datasets now permits an unprecedented ability to constraintime-variability on the surface from apparent changes due toviewing geometry and surface inhomogeneities This work requiresa reconcilliation of surface scattering properties that are enabled bythe firm determination of the size of Pluto and this will bediscussed as well This work was supported by the NASA NewHorizons project

Author(s) Marc W Buie S Alan Stern Leslie A Young Harold A Weaver Catherine B Olkin Kimberly Ennico JeffreyM Moore William M GrundyInstitution(s) 1 JHUApplied Physics Laboratory 2 LowellObservatory 3 NASA Ames Research Center 4 SouthwestResearch Institute

20004 ndash Migration of Frosts from High-AlbedoRegions of Pluto what New Horizons RevealsWith its high eccentricity and obliquity Pluto should exhibitseasonal volatile transport on its surface Several lines of evidencesupport this transport doubling of Plutorsquos atmospheric pressureover the past two decades (Young et al 2013 Ap J 766 L22Olkin et al 2015 Icarus 246 230) changes in its historicalrotational light curve once all variations due to viewing geometryhave been modelled (Buratti et al 2015 Ap J 804 L6) andchanges in HST albedo maps (Buie et al 2010 Astron J 1391128) New Horizons LORRI images reveal that the region ofgreatest albedo change is not the polar cap(s) of Pluto but thefeature informally named Tombaugh Regio (TR) This feature hasa normal reflectance as high as ~08 in some places and it issuperposed on older lower-albedo pre-existing terrain with analbedo of only ~010 This contrast is larger than any other body inthe Solar System except for Iapetus This albedo dichotomy leadsto a complicated system of cold-trapping and thermal segregationbeyond the simple picture of seasonal volatile transport Whateverthe origin of TR it initially acted as a cold trap as the temperaturedifferential between the high and low albedo regions could beenormous possibly approaching 20K based on their albedodifferences and assuming their normalized phase curves aresimilar This latter assumption will be refined as the full NewHorizons data set is returnedOver six decades of ground-based photometry suggest that TR hasbeen decreasing in albedo over the last 25 years Possible causesinclude changing insolation angles or sublimation from the edgeswhere the high-albedo material impinges on a much warmersubstrateFunding by the NASA New Horizons Project acknowledged

Author(s) Bonnie J Buratti S A Stern Hal A Weaver Leslie A Young Cathy B Olkin Kimberly Ennico Richard PBinzel Amanda Zangari Alissa M EarleInstitution(s) 1 JHU Applied Physics Lab 2 JPL 3 MIT 4NASA Ames 5 SWRI

20005 ndash Correlating Plutos Albedo Distribution toLong Term Insolation PatternsNASAs New Horizons reconnaissance of the Pluto system hasrevealed striking albedo contrasts from polar to equatorial latitudeson Pluto as well as sharp boundaries for longitudinal variationsThese contrasts suggest Pluto undergoes dynamic evolution thatdrives the redistribution of volatiles Using the New Horizonsresults as a template in this talk we will explore the volatilemigration process driven seasonally on Pluto considering multipletimescales These timescales include the current orbit (248 years)as well as the timescales for obliquity precession (amplitude of 23degrees over 3 Myrs) and regression of the orbital longitude ofperihelion (37 Myrs) We will build upon the long-term insolationhistory model described by Earle and Binzel (2015 Icarus 250405-412) with the goal of identifying the most critical timescalesthat drive the features observed in Plutorsquos current post-perihelionepoch This work was supported by the NASA New HorizonsProject

Author(s) Alissa M Earle Richard P Binzel S AlanStern Leslie A Young Bonnie J Buratti Kimberly Ennico Will M Grundy Catherine B Olkin John R Spencer Hal AWeaverInstitution(s) 1 Jet Propulsion Laboratory 2 Johns HopkinsUniversity Applied Physics Lab 3 Lowell Observatory 4Massachusetts Institute of Technology 5 NASA Ames ResearchCenter 6 Southwest Research Institute

20006 ndash A Large Impact Origin for Sputnik Planum

2 3 64 4 3 4

5 6 8 56 6 6 9 5

6 6 6 610 1 6 11 6

7

2 4 2 62 2

2

2

22

2

5 34 3 2

5 6 5 15

4 4 41 4 3

3 2

2 5 15 5 4

3 5 3

4 46 6 1 5

3 6 62

23

and Surrounding Terrains PlutoOne of the most prominent features on Pluto discovered by NewHorizons is the oval-shaped bright deposit within westernTombaugh Regio (all names used herein are informal) Thissmooth bright deposit provisionally identified with frozen nitrogenand methane and informally referred to as Sputnik Planum isbounded on the northeast by an arcuate scarp (Cousteau Rupes)The smooth bright material there embays what appears to be aneroded plateau 1-2 km high The arcuate scarp leads to speculationthat the deposits formed in an ancient impact basin but detailedmapping at 2 km pixel scales suggests that this large structure ismore complex than any simple impact basin To the southwest area series of high peaks and massifs (also embayed by brightmaterial) but these broken massifs have a different morphologyfrom Cousteau Rupes being both higher and more disrupted Thesouthern section of this putative 800-km-wide circular structure iscompletely missing as smooth material extends well to the south ofthe nominal rim location A possible analog occurs at the ldquootherEnd of the Solar Systemrdquo on Mercury in Caloris Basin This1400-km-wide impact basin is also irregular in shape with largedeviations form circularity and occasional large massifs alongsome rim segments Post-impact smooth plains embay the rimscarp in some areas though these are likely to be volcanic plains onMercury The relief of the rim scarps to the NE and SW andputative evidence for convection within Sputnik Planum suggeststhat the floor of the deposits lies 1-3 km below the mean surface(pending stereo mapping) This depth is consistent with the fillingof an ancient impact basin with ices deposited either volcanicallyor atmospherically although other explanations are also possibleThis work was supported by NASAs New Horizons project

Author(s) Paul M Schenk William McKinnon JeffreyMoore Francis Nimmo S Alan Stern Hal Weaver KimberlyEnnico Cathy Olkin Leslie YoungInstitution(s) 1 Applied Physics Lab 2 Lunar and PlanetaryInst 3 NASA Ames Res Ctr 4 Southwest Research Institute 5UC Santa Cruz 6 Washington University

20007 ndash The Icy Cold Heart of PlutoThe locations of large deposits of frozen volatiles on planetarysurfaces are largely coincident with areas receiving the minimumannual influx of solar energy familiar examples include the polarcaps of Earth and Mars For planets tilted by more than 45 degreeshowever the poles actually receive more energy than some otherlatitudes Pluto with its current obliquity of 119 degrees hasminima in its average annual insolation at +- 27 degrees latitudewith ~15 more energy flux going to the equator and ~15 moreto the poles Remarkably the fraction of annual solar energyincident on different latitudes depends only on the obliquity of theplanet and not on any of its orbital parametersOver millions of years Plutos obliquity varies sinusoidally from102-126 degrees significantly affecting the latitudinal profile ofsolar energy deposition Roughly 1Myr ago the poles received 15more energy that today while the equator received 13 less Theenergy flux to latitudes between 25-35 degrees is far more stableremaining low over the presumably billions of years since Plutoacquired its current spin properties Like the poles at Earth thesemid latitudes on Pluto should be favored for the long-termdeposition of volatile ices This is indeed the location of the brighticy heart of Pluto Sputnik PlanumReflected light and emitted thermal radiation from Charonincreases annual insolation to one side of Pluto by of order 002Although small the bulk of the energy is delivered at night toPlutos cold equatorial regions Furthermore Charons thermalinfrared radiation is easily absorbed by icy deposits on Plutoslowing deposition and facilitating sublimation of volatiles Weargue that the slight but persistent preference for ices to form andsurvive in the anti-Charon Plutos heart

Author(s) Douglas P HamiltonInstitution(s) 1 Univ of Maryland

20008 ndash Pluto and Charon Color Light Curves fromNew Horizons on Approach

On approach to the Pluto system New Horizonsrsquo RalphInstrumentrsquos Multicolor Visible Imaging Camera (MVIC) observedPluto and Charon spatially separated between April 9 and June23 2015 In this period Pluto and Charon were observed totransition from unresolved objects to resolved and their integrateddisk intensities were measured in four MVIC filters blue (400-550nm) red (540-700 nm) near-infrared (780ndash975 nm) andmethane (860ndash910 nm) The measurement suite sampled thebodies over all longitudes We will present the color rotational lightcurves for Pluto and Charon and compare them to previous (BuieM et al 2010 AJ 139 1117 Buratti BJ et al 2015 ApJ 804 L6) andconcurrent ground-based BVR monitoring We will also comparethese data to color images of the encounter hemisphere takenduring New Horizonsrsquo July 14 2015 Pluto and Charon flyby as thisdata set provides a unique bridge between Pluto amp Charon asviewed as astronomical targets versus the complex worlds that earlydata from New Horizons has revealed them to be This work wassupported by NASArsquos New Horizons project

Author(s) Kimberly Ennico C JA Howett C B Olkin D C Reuter B J Buratti M W Buie W M Grundy A HParker A M Zangari R P Binzel J C Cook D PCruikshank C M Dalle Ore A M Earle D E Jennings I RLinscott J Wm Parker S Protopapa K N Singer J RSpencer S A Stern C CC Tsang A J Verbiscer H AWeaver L A YoungInstitution(s) 1 Jet Propulsion Laboratory 2 Johns HopkinsUniversity Applied Physics Laboratory 3 Lowell Observatory 4Massachusetts Institute of Technology 5 NASA Ames ResearchCenter 6 NASA Goddard Space Flight Center 7 SETI Institute 8Southwest Research Institute 9 Stanford University 10University of Maryland 11 University of Virginia

20009D ndash Plutos atmosphere from stellaroccultations in 2012 and 2013We present results from two Pluto stellar occultations observed on18 July 2012 and 04 May 2013 and monitored respectively fromfive and six sites in South America Both campaigns involved largetelescopes (including the 82-m VLT at ESOParanal) The highSNR ratios and multi-chord coverage provide amoung the bestPluto atmospheric profiles ever obtained from the groundWe show that a spherically symmetric clear (no-haze) and pure N2atmosphere with a unique temperature profile satisfactorily fits thetwelve lightcurves provided by the two events We find however asmall but significant increase of pressure of 6 (6-sigma level)between the two dates with values of 216 plusmn 02 and 230 plusmn 001μbar at the reference radius 1275 km respectivelyWe provide atmospheric constrains between 1190 km and 1450 kmfrom Plutos center and we determine the temperature profile withaccuracy of a few km in vertical scale Our model shows astratosphere with strong positive gradient between 1190 km (at 36K 11 μbar) and r =1215 km (60 μbar) where a temperaturemaximum of 110 K is reached Above it is a mesosphere withnegative thermal gradient of -02 Kkm up to 1390 km (025 μbar)at which point the mesosphere connects itself to a moreisothermal upper branch at 81 K This profile provides (assumingno troposphere) a Pluto surface radius of 1190 plusmn 5 km consistentwith preliminary values obtained by New Horizons Currentlymeasured CO abundances are too low to explain the negativemesospheric thermal gradient We explore the possibility of anHCN (recently detected by ALMA) cooling This model howeverrequires largely supersaturated HCN Zonal winds and verticalcompositional variations of the atmosphere are also unable toexplain the observed mesospheric trendThese events are the last useful ground-based occultationsrecorded before the 29 June 2015 occultation observed fromAustralia and New Zealand and before the NASAs New Horizonsflyby of July 2015 This work can serve as a benchmark in the NewHorizons context enabling comparisons between ground-basedand space results concerning Plutos atmospheric structure andtemporal evolution

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24

Author(s) Alex Dias-Oliveira Bruno Sicardy EmmanuelLellouch Roberto Vieira-Martins Marcelo Assafin JuacutelioIgnaacutecio Bueno Camargo Felipe Braga-Ribas Altair Gomes-Juacutenior Gustavo Bendetti-Rossi Franccedilois Colas AliceDecock Alain Doressoundiram Christophe Dumas MarceloEmiacutelio Joaquin Fabrega Polleri Ricardo Gil-Hutton MichaelGillon Julien Girard George Hau Valentin Ivanov Emmanuel Jehin Jean Lecacheux Rodrigo Leiva CeciacuteliaLopez-Sisterna Luigi Mancini Jean Manfroid AlainMaury Erick Meza Nicolas Morales Leslie Nagy CyrielleOpitom Joseacute Luiz Ortiz Joe Pollock Franccediloise Roques Colin Snodgrass Jean Franccedilois Soulier Audrey Thirouin Leonardo Vanzi Thomas Widemann Daniel Reichart AaronLaCluyze Joshua B Haislip Kevin Ivarsen MartinDominik Uffe Joslashrgensen Jesper SkottfeltInstitution(s) 1 Appalachian State University 2 AssociationDes Etoiles pour Tous 3 CASLEO-CONICET 4 ESO 5 ESO 6Instituto de Astrofiacutesica de Andaluciacutea 7 Lowell Observatory 8Max Planck Institute for Astronomy 9 Observatoire deParisIMCCE 10 Observatoire de ParisLESIA 11 Observatoacuteriodo ValongoUFRJ 12 Observatoacuterio Nacional 13 ObservatoacuterioPanemntildeo 14 PUC 15 SPACE 16 The Open University 17UEPG 18 Universidade Nacional de San Juan 19 Universiteacute deLiege 20 University of Copenhagen 21 University of NorthCarolina 22 University of St Andrews 23 UTFPR

201 ndash sup3Venus Asteroid Dynamics20101D ndash The effect of solar flares coronal massejections and co-rotating interaction regions on theVenusian 5577 nm oxygen green lineThe Venusian 5577nm OI (1S - 1D) (oxygen green line) nightglowemission is known to be highly temporally variable The reason forthis variability is unknown We propose that the emission is due toelectron precipitation from intense solar storms For mydissertation I observed the Venusian green line after solar flarescoronal mass ejections (CMEs) and co-rotating interaction regionsfrom December 2010 to April 2015 using the high resolutionAstrophysical Research Consortium Echelle Spectrograph on theApache Point Observatory 35-m telescope Combining theseobservation with all other published observations we find that thestrongest detections occur after CME impacts and we concludeelectron precipitation is required to produce green line emissionWe do not detect emission from the 6300nm OI (1D - 3P) oxygenred line for any observationIn an effort to determine the emitting altitude therebyconstraining the possible emission processes responsible for greenline emission and quantify the electron energy and flux enteringthe Venusian nightside we conducted analyses of space-basedobservations of the Venusian nightglow and ionosphere collectedby the Venus Express (VEX) spacecraft We were unable to detectthe green line but confirmed that electron energy and fluxincreases after CME impactsIn order to determine the effect of storm condition electronprecipitation on the Venusian green line we modeled the Venusianionosphere using the TRANSCAR model (a 1-Dmagnetohydrodynamic ionospheric model that simulates auroralemission from electron precipitation) by applying observedelectron energies and fluxes We found that electron energy plays aprimary role in producing increased green line emission in theVenusian ionosphereBased on observation and modeling results we conclude that theVenusian green line is an auroral-type emission that occurs aftersolar storms with the largest intensities observed after CMEsPost-CME electron fluxes and energies are sufficient to producethe observed green line intensity with the lack of red line emissionWe find that O + e is the greatest contributor to the OI (1S) stateand is responsible for the observed green line emission

Author(s) Candace L Gray Nancy Chanover TomSlanger Karan Molaverdikhani Kerstin Peter Bernd Haumlusler Silvia Tellmann Martin Paumltzold Olivier Witasse Pierre-LouisBlelly Glyn CollinsonInstitution(s) 1 European Space Research and TechnologyCentre 2 Institut de Recherche en Astrophysique et Planeacutetologie 3 Laboratory for Atmospheric and Space Physics 4 NASAGoddard Space Flight Center 5 New Mexico State University 6SRI International 7 Universitaumlt der Bundeswehr Muumlnchen 8University of Koln

20102 ndash Variability of the Venus condensationalclouds from analysis of VIRTIS-M-IR observations ofthe near-infrared spectral windowsThe Medium Resolution Infrared wavelength channel of theVisible and Infrared Thermal Imaging Spectrometer(VIRTIS-M-IR) on the Venus Express spacecraft observed theatmosphere and surface of Venus for 921 orbits following orbitinsertion in April 2006 until the failure of the cooling unit inOctober 2008 The clouds of Venus were long thought to be auniform sort of perpetual stratocumulus but near infraredobservations by fly-by spacecraft such as Galileo (Near InfraredMapping Spectrometer) and Cassini (Visible and Infrared MappingSpectrometer) as well as ground-based observations indicated agreat deal of temporal and spatial inhomogeneity The nearlythree-year lifetime of the VIRTIS-M-IR instrument on VenusExpress presents an unprecedented opportunity to quantify thesespatial and temporal variations of the Venus clouds Here wepresent the results of an initial quantification of the overalltendencies of the Venus clouds as measured by variations in thenear infrared spectral windows located between wavelengths of 10microm and 26 microm In a companion submission we also investigatethe variations of carbon monoxide and other trace speciesquantifiable in these data (Tsang and McGouldrick 2015) Thiswork is supported by the Planetary Mission Data Analysis ProgramGrant Number NNX14AP94G

Author(s) Kevin McGouldrick Constantine C C TsangInstitution(s) 1 Southwest Research Institute 2 University ofColorado

20103 ndash Thermal structure and minor speciesdistribution of Venus mesosphere by ALMA submmobservationsVenus upper atmosphere (70ndash150 km altitude) is a transitionregion characterized by a complex dynamics strong retrogradezonal winds dominate the lower mesosphere while a solar-to-antisolar circulation is observed in the upper mesospherelowerthermosphere In addition photochemical processes play animportant role at these altitudes and affect the thermal structureand chemical stability of the entire atmosphere Sulfur dioxide andwater vapor are key species in the photochemical cycles takingplace in the troposphere and mesosphere of Venus They arecarried by convective transport together with the Hadleycirculation up to about 60 km where SO is photodissociated andoxydated leading to the formation of H SO which condenses inthe clouds enshrouding the planet Previous observations obtainedby several instruments on board Venus Express and duringground-based campaigns have shown evidence of strong temporalvariations both on day-to-day as well as longer timescales ofdensity temperature and SO abundance Such strong variability isstill not well understoodSubmillimeter observations obtained with the Atacama LargeMillimeter Array (ALMA) offer the possibility of probing Venusupper mesosphere and of monitoring minor species winds and thethermal structure A first set of observations was obtained onNovember 14 15 26 and 27 2011 during the first ALMA EarlyScience observation cycle These observations targeted SO SOHDO and CO transitions around 345 GHz during four sequences of30 minutes each The Venusrsquo disk was about 11rdquo with anillumination factor of 90 so that mostly the dayside of the planetwas mappedAssuming nominal night-time and dayside CO abundance profilesfrom Clancy et al 2013 we retrieved vertical temperature profiles

12 1010 12 11

12 2311 12 910 10 5

17 13 319 5 5 4

19 9 1418 8 19

15 10 6 1519 6 1 10

16 2 714 10 7

21 21 2122 20 20

5 56 3 8 7

8 8 12 4

2 1

22 4

2

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25

over the entire disk as a function of latitude and local time for thefour days of observation Temperature profiles were later used toderive the abundances of minor species (HDO SO SO ) in eachpixel of the disk in order to study their spatial and temporalvariability

Author(s) Arianna Piccialli Raphael Moreno ThereseEncrenaz Thierry Fouchet Emmanuel Lellouch ArielleMoullet Thomas WidemannInstitution(s) 1 LESIA Observatoire de Paris 2 NationalRadio Astronomy Observatory (NRAO)

20104 ndash Observations of Altitude Dependence andTemporal Variation of ClO in the Venus MesosphereAnalysis of the first observations of ClO in the Venus mesosphereindicate ClO is present above 85 +-3 km altitude and not belowThe retrieved nightside mean abundances show a factor of 2decrease between observation dates Oct 23 and Nov 11 2015 withchange between the two dates evident at more than two sigmaconfidence Abundances and altitude distributions are retrievedfrom submm spectroscopic observations of the 35288 GHz line of

ClO (made with the James Clerk Maxwell Telescope - JCMT -located an Mauna Kea Hawaii)Detection of ClO in the Venus atmosphere confirms a theory putforward by Yung and DeMore (1982) that the Venus atmosphere isstabilized as CO due to chlorine catalytic recombination of CO andO (Without some form of catalysis the Venus atmosphere wouldhave 10s of percent CO and O but it is in fact 97 CO and 3N with only trace amounts of CO and O ) Detailed retrieval ofClO abundances and altitude distributions (the focus of this talk)provides greater insight to the catalytic process and to otheraspects of Venus atmospheric chlorine chemistry We comparefindings of our quantitave retrieval with predictions ofphotochemical models and discuss the implications for chlorinephotochemisty of the Venus atmosphere We also discuss retrievedClO temporal variation with that of upper mesospheric HCl(Sandor and Clancy 2012)[We acknowledge funding of this project by NASA grantsNNX10AB33G NNX12AI32G and NNX14AK05G as well as NSFgrant AST-1312985]

Author(s) Brad J Sandor R Todd ClancyInstitution(s) 1 Space Science Institute

20105 ndash A refined orbit for the satellite of asteroid(107) CamillaThe satellite of the Cybele asteroid (107) Camilla was discovered inMarch 2001 using the Hubble Space Telescope (Storrs et al 2001IAUC 7599) From a set of 23 positions derived from adaptiveoptics observations obtained over three years with the ESO VLTKeck-II and Gemini-North telescopes Marchis et al (2008 Icarus196) determined its orbit to be nearly circularIn the new work reported here we compiled reduced and analyzedobservations at 39 epochs (including the 23 positions previouslyanalyzed) by adding additional observations taken from dataarchives HST in 2001 Keck in 2002 2003 and 2009 Gemini in2010 and VLT in 2011 The present dataset hence contains twice asmany epochs as the prior analysis and covers a time span that isthree times longer (more than a decade)We use our orbit determination algorithm Genoid (GENetic OrbitIDentification) a genetic based algorithm that relies on ametaheuristic method and a dynamical model of the Solar System(Vachier et al 2012 AampA 543) The method uses two models asimple Keplerian model to minimize the search-time for an orbitalsolution exploring a wide space of solutions and a full N-bodyproblem that includes the gravitational field of the primary asteroidup to 4th orderThe orbit we derive fits all 39 observed positions of the satellitewith an RMS residual of only milli-arcseconds which correspondsto sub-pixel accuracy We found the orbit of the satellite to becircular and roughly aligned with the equatorial plane of CamillaThe refined mass of the system is (12 plusmn 1) x 10^18 kg for an orbitalperiod of 371 daysWe will present this improved orbital solution of the satellite of

Camilla as well as predictions for upcoming stellar occultationevents

Author(s) Myriam Virginia Pajuelo Benoit Carry Frederic Vachier Jerome Berthier Pascal Descamp William JMerline Peter M Tamblyn Al Conrad Alex Storrs Jean-LucMargot Frank Marchis Pierre Kervella Julien H GirardInstitution(s) 1 ESO 2 IMCCE Observatoire de Paris 3 LargeBinocular Telescope Observatory 4 LESIA Observatoire de Paris5 SETI Institute 6 Southwest Research Institute 7 TowsonUniversity 8 UCLA

20106 ndash On the oldest asteroid families in the mainbeltAsteroid families are group of minor bodies produced by collisionsOnce the parent body is disrupted by a collision and fragments arelaunched into space their orbits evolve because of severalgravitational and non-gravitational effects such as diffusion inmean-motion resonances Yarkovsky and YORP effects collisionalevolution etc The subsequent dynamical evolution of asteroidfamily members may cause some of the original fragments to travelbeyond the recognizable limits of the asteroid family Eventuallythe whole family will dynamically disperse and no longer berecognizable Dynamical erosion of asteroid families has been thesubject of a few recent studies mostly focused on smaller asteroidgroupsA natural question that may arise concerns the timescales fordispersion of large families In particular what is the oldest stillrecognizable family in the main belt Are there any families thatmay date from the late stages of the Late Heavy Bombardment andthat could provide clues on our understanding of the primitiveSolar System In this work we investigate the dynamical stability ofseven of the allegedly oldest families in the asteroid main beltwhen resonant dynamics Yarkovsky and stochastic YORP effectsand past changes in the solar luminosity are considered None ofthe studied families is estimated to be older than 30 Gyr Resultsof our numerical simulations show that some of the members ofthe largest families studied could have survived since 42 Gyr butwith a significant depletion in the number of the smallest (D lt 5km) family members

Author(s) Valerio Carruba David Nesvornyacute SafwanAljbaae Rita C DomingosInstitution(s) 1 SouthWest Research Institute 2 UNESP

20107 ndash Asteroid Impacts Crater Scaling Laws and aProposed Younger Age for Venuss SurfaceA fascinating on-going debate concerns the asteroid sizes needed toform certain large craters For example numerical hydrocodemodels predict that ~12-14 km and ~8 km diameter asteroids areneeded to produce craters like Chicxulub (~180 km) and Popigai(~100 km) respectively The abundance of extraterrestrial IrOsmeasured at well-characterized impact boundaries on land and inoceanic cores however predict far smaller projectiles 4-6 km and25-4 km respectively (eg Paquay et al 2014 F Kyte perscomm) To test who might be right by proxy we transformed thenear-Earth object (NEO) size distribution (Harris amp DAbramo2015) where gt 90 of the D gt 1 km asteroids are known into amodel crater size distribution and compared it to the distribution ofD gt 20 km craters formed on the Moon Mars and Venus over thelast ~1-3 Gyr Here we kept things simple and assumed that fdescribed the ratio between all crater and asteroid diameters ofinterest (ie f = D_crater D_proj)To our surprise we found f ~ 23-26 produced excellent matches forthe crater size distributions on the Moon Mars and Venus despitetheir differences in gravity surface properties impact velocitiesetc These same values work well for the Earth as well Considerthat terrestrial crater production rates derived by Shoemaker(1998) indicate 340 +- 170 D gt 20 km craters formed over the last120 Myr Using f = 25 we get the same value a D gt 08 km asteroidmakes a D gt 20 km crater and they hit Earth every 035 Myr onaverage (eg Bottke et al 2002) for a total of ~340 over 120 MyrAccordingly we predict Chicxulub and Popigai were made by D ~ 7and D ~ 4 km asteroids respectively values close to their predicted

2

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35

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6 6 3 78 5 4 1

1 12 2

26

sizes from IrOs measurements This result also potentiallyexplains why Chicxulub formed ~65 Myr ago the interval betweenD ~ 7 km impacts on Earth is close to this rateThe NEO model by Bottke et al (2002) also suggests asteroids hitVenus at roughly the same rate as Earth Fitting model craters toobservations we estimate Venusrsquo average surface age as ~130 Myra lower value than previous predictions This result if true hasinteresting implications for Venusrsquos evolutionary history

Author(s) William Bottke Rebecca Ghent Sara Mazrouei Stuart Robbins David VokrouhlickyInstitution(s) 1 Charles U 2 Southwest Research Inst 3 UToronto

20108 ndash Sesquinary catanae on Phobos fromreaccretion of ejected materialImpact ejecta from a planetary satellite can reimpact the targetbody or nearby companions after an extended period creating adistinct type of lsquosesquinaryrsquo impact morphology We presentresults of a comprehensive survey of sesquinary ejecta releasedfrom the Martian satellite Phobos ranging from ejecta from theStickney impact (outcomes of SPH simulations) to just-escapingejecta particles (Z-model formulation) released from locations atwhich Phobos both overflows its Roche lobe and is inside that lobe(sub and anti-Mars points) Third body solar perturbations andhigh-order harmonics terms are implemented in a highly accurateephemerides formulation to model the dynamical evolution ofejecta in the Mars gravity system and chart locations of eventualreaccretions for comparison with Phobos crater morphologyThe slowest ejecta is found to reaccrete in multiple low-velocitychain-like clusters similar to catanae observed on Ganymede Callisto and Mars on characteristic timescales of 1-10 yearsThe morphological similarity to linear pitted chains on Phobossuggests that this formation mechanism may constrain families ofgrooves that do not fit well to a tidal model for groove origin Ejecta released from a primordial Phobos orbit about Mars donot result in catanae implying that these are geologically recentand no older than Phobosrsquos modern orbit Work is ongoing toconstruct a more detailed correlation between sesquinary catenaeand pitted grooves on Phobos and possible source cratersLongitudinal and latitudinal variations in the location of theprimary cratering event velocity distributions from 1-10 kmcraters orbital position with relation to Mars and conjunctions withDeimos are all treated as free parameters catanae-like clusters arefound in all cases This persistence suggests that the creation oflow-velocity clustered impact structures from sesquinary ejecta is arelatively frequent process on Phobos its effect on surface geologyhas implications for theories surrounding the origin of the familiesof grooves[1] Zahnle et al 2008 Icarus [2] Melosh amp Schenk 1993 Nature[3] Ferrill et al 2004 GSA Today [4] Asphaug et al 2015 EPSC[5] Yoder 1982 Icarus

Author(s) Michael Nayak Erik AsphaugInstitution(s) 1 Arizona State University 2 University ofCalifornia Santa Cruz

20109 ndash Surface Evolution from Orbital Decay onPhobosPhobos the innermost satellite of Mars displays an extensivesystem of grooves that are mostly symmetric about its sub-Marspoint Phobos is steadily spiraling inward due to the tides it raisesand will suffer tidal disruption before colliding with Mars Wecalculate the surface stress field of the de-orbiting satellite andshow that the first signs of tidal disruption are already present onits surface Most of Phobosrsquo prominent grooves have an excellentcorrelation with computed stress orientations The model predictsan interior that has very low strength on the tidal evolutiontimescale overlain by a ~10-100 m exterior shell that has elasticproperties similar to lunar regolithShortly after the Viking spacecraft obtained the first geomorphicimages of Phobos it was proposed that stresses from orbital decaycause grooves But assuming a homogeneous Phobos it provedimpossible to account for the build-up of failure stress in the

exterior regardless of the value assumed for Phobosrsquo rigidityHence the tidal model languished Here we revisit the tidal originof surface fractures with a more detailed treatment that shows theproduction of significant stress in a surface layer with a very strongcorrelation to the geometry of groovesOur model results applied to surface observations imply thatPhobos has a rubble pile interior that is nearly strengthless Alunar-like cohesive regolith outer layer overlays the rubble pileinterior This outer layer behaves elastically and can experiencesignificant tidal stress at levels able to drive tensile failure Fissurescan develop as the global body deforms due to increasing tidesrelated to orbital decay Phobos may have an active and evolvingsurface an exciting target for further exploration The interiorpredictions of this model can be evaluated by future detailedstudies performed by an orbiter or lander

Author(s) Terry Hurford Erik Asphaug Joseph Spitale Douglas Hemingway Alyssa Rhoden Wade Henning BruceBills Simon Kattenhorn Matthew WalkerInstitution(s) 1 Arizona State University 2 ConocoPhillipsCompany 3 JPL 4 NASA GSFC 5 Planetary Science Institute 6University of California Los Angeles 7 University of CaliforniaSanta Cruz

202 ndash EPO - Scientists Showcase20201 ndash Science Communication at NASAScientists usually excel in a particular discipline but generally havea difficult time informing and engaging the public about what wedo From climate science to natural hazards risks our science doesaffect peoples lives Within NASA we have started sciencecommunications training focusing on how to tell a clear storyabout not just what we do but why we do it This not only will helpus better communicate to our stakeholders and the public but alsohopefully make for better communications within our diverseteams

Author(s) Ellen R StofanInstitution(s) 1 NASA

20202 ndash Confessions of an Accidental EPOnomerfrom in Front of the Camera and Behind the PixelsThe various techniques styles and venues for popularizing theresearch outputs from our planetary science community reflect thediversity of the community itself While some are eloquent publicspeakers or gifted writers other colleagues are regularly sought fortelevision appearances or for artwork to illustrate press releasesWhatever the method or medium the collection of experiences wehave had in lsquogetting the word outrsquo represents a valuable resourcepool of ideas and lessons learned from which we can all learn andimprove I will share some of my experiences from working with anumber of television productions and magazine editors with somethoughts on contemporary television production styles I will alsodiscuss life as both a planetary scientist and digital artist and sharesome resources that are ready willing and quite able to help tellthe visual story of your research

Author(s) Daniel D DurdaInstitution(s) 1 Southwest Research Inst

20203 ndash Hazardous Asteroids Cloaking STEM SkillsTraining within an Attention-Grabbing ScienceMathCourseA graduate-level course was designed and taught during thesummer months from 2009 ndash 2015 in order to contribute to thetraining and professional development of K-12 teachers residing inthe Southwest The teachers were seeking Masterrsquos degrees via theNew Mexico Institute of Mining and Technologyrsquos (NMTrsquos)Masters of Science Teaching (MST) program and the coursesatisfied a science or math requirement The MST programprovides opportunities for in-service teachers to enhance theircontent backgrounds in science mathematics engineering andtechnology (SMET) The ultimate goal is to assist teachers in

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[1]

[2][2] [3]

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gaining knowledge that has direct application in the classroomThe engaging topic area of near-Earth object (NEO)characterization studies was used to create a fun and excitingframework for mastering basic skills and concepts in physics andastronomy The objective was to offer a class that had theappropriate science rigor (with an emphasis on mathematics)within a non-threatening format The course entitled ldquoHazardousAsteroidsrdquo incorporates a basic planetary physics curriculum withchallenging laboratories that include a heavy emphasis on mathand technology Since the authors run a NASA-funded NEOresearch and follow-up program also folded into the course is theuse of the Magdalena Ridge Observatoryrsquos 24-meter telescope soparticipants can take and reduce their own data on a near-EarthasteroidIn exit assessments the participants have given the courseexcellent ratings for design and implementation and the overalldegree of satisfaction was high This validates that awell-constructed (and rigorous) course can be effective inreceptively reaching teachers in need of basic skills refreshmentMany of the teachers taking the course were employed in schooldistricts serving at-risk or under-prepared students and the coursehelped provide them with the confidence vital to developing newstrategies for successful teaching

Author(s) Eileen V Ryan William H RyanInstitution(s) 1 NM TechMRO

20204 ndash Blending Entertainment Education andScience in a Modern Digital PlanetariumStudents at the University of Arizona have a relatively rareopportunity to learn in a state-of-the-art planetarium Originallyopened as a campus planetarium in 1975 the Flandrau ScienceCenter recently expanded into the digital realm In 2014 Flandraursquosantique Minolta star projector was joined by a full-dome 4K digitalprojection system powered by a high performance computercluster Currently three science courses are taught in theplanetarium for non-science majors mdash stellar astronomyastrobiology and planetary science (taught by SJK)The new digital system allows us to take our classes off the surfaceof Earth on a journey into the cosmos Databases from dozens ofspacecraft missions and deep-space telescopic surveys are tappedby the software to generate a realistic immersive 3D perspective ofthe universe from local planets satellites and rings to distant starsand galaxies all the way out to the limit of the visible universeSimple clicks of a mouse allow us to change the orientationtrajectory and speed of the virtual spacecraft giving our studentsdiverse views of different phenomenaThe challenge with this system is harnessing the entertainmentaspect for educational purposes The visualization capabilities allowus to artificially enhance certain features and time scales Forexample the sizes of Earth and the moon can be enlargedon-the-fly to help demonstrate phases and eclipses Polar axes andlatitude lines can be added to Earth as it orbits the sun to helpconvey the reasons for seasons Orbital paths can be highlighted toallow students to more accurately comprehend the population ofnear-Earth asteroidsThese new immersive computer-generated visualizationtechniques have the potential to enhance comprehension inscience education especially for concepts involving 3D spatial andtemporal relationships Whether or not this potential is beingrealized will require studies to gauge student learning and retentionbeyond the short-term semester-long course This work is justbeginning

Author(s) Stephen J KortenkampInstitution(s) 1 Planetary Science Institute

20205 ndash Going Above amp Beyond Astronomy as thePublicrsquos Gateway to ScienceMany of the worldrsquos most pressing scientific issues fall outside thepurview of astronomy Climate change vaccination geneticmodification and other similar topics are embroiled in the trenchesof an ideological war in the public sphere which creates asometimes-insurmountable obstacle to discussion This talk will

describe a show series developed at Fiske Planetarium that uses thepublicrsquos remarkable appetite for space content as a means forengaging indirectly with these contentious topics It also promotesthe planetarium as a place for interdisciplinary learning and offersthe opportunity for the broader population to engage with youngscientists in a different light

Author(s) Morgan RehnbergInstitution(s) 1 CULASP

20206 ndash Investigating Changes in Studentsrsquo AttitudesTowards Science During an Adaptive OnlineAstrobiology CourseOnline education is an emergent sector of formal education andArizona State University (ASU) is a leader in offering onlinecourses One that garners very strong positive feedback on studentsurveys is Habitable Worlds which is an interdisciplinary onlinescience course offered every semester since Fall 2011 Primarygoals of this course are to teach understanding of scientificreasoning and practices by using principles from trans-disciplinaryresearch in astrobiology To examine course outcomes weadministered the Classroom Undergraduate Research Experience(CURE) survey which has been previously developed to measurestudent experiences Here we use the survey for the first time foran online course The survey was taken before and after completingthe course during the Fall 2014 and Spring 2015 semesters (N =544) Here we present studentsrsquo views of science represented by 22questions on the survey For the questions students respondedeither not applicable strongly disagree disagree neutralagree or strongly agree In order to interpret the data wedivided the questions into three broader categories for analysisstudentsrsquo understanding of the scientific process studentsrsquoscientific self-efficacy and studentsrsquo views on science teaching Westudy how the sample of students changed their responses to eachof the questions as a group by using a paired-samples sign test togauge the statistical significance of the difference between pre andpost responses We further analyze how individual studentschanged their responses For example we designated a changefrom ldquostrongly disagreerdquo to ldquodisagreerdquo differently than a changefrom ldquoagreerdquo to ldquodisagreerdquo since the latter indicated a notablechange in the studentrsquos opinion We found statistically significantchanges on 12 of the 22 questions These early results indicate thatthere are measurable changes on several identified courseobjectives By measuring changes that occurred to the whole groupof students as well as identifying in detail what type of changesoccurred from student to student for each question we will be ableto improve future offerings of the course as well as to make broaderconclusions about online science education

Author(s) Viranga Perera Sanlyn R Buxner LevHorodyskyj Ariel Anbar Steven Semken Chris Mead DavidLopattoInstitution(s) 1 Arizona State University 2 Grinnell College 3University of Arizona

20207 ndash The Arecibo Observatory Space AcademyThe Arecibo Observatory Space Academy (AOSA) is a ten (10) weekpre-college research program for students in grades 9-12 Ourmission is to prepare students for academic and professionalcareers by allowing them to receive an independent andcollaborative research experience on topics related to space andaide in their individual academic and social development Ourobjectives are to (1) Supplement the studentrsquos STEM education viainquiry-based learning and indirect teaching methods (2) Immersestudents in an ESL environment further developing their verbaland written presentation skills and (3) To foster in every studentan interest in science by exploiting their natural curiosity andknowledge in order to further develop their critical thinking andinvestigation skills AOSA provides students with the opportunityto share lectures with Arecibo Observatory staff who haveexpertise in various STEM fields Each Fall and Spring semesterselected high school students or Cadets from all over Puerto Ricoparticipate in this Saturday academy where they receive experiencedesigning proposing and carrying out research projects related to

1 1

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1

1 31 1 1 1

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space exploration focusing on four fields PhysicsAstronomyBiology Engineering and Sociology Cadets get the opportunity toexplore their topic of choice while practicing many of thefoundations of scientific research with the goal of designing a spacesettlement which they present at the NSS-NASA Ames SpaceSettlement Design Contest At the end of each semester studentspresent their research to their peers program mentors and AreciboObservatory staff Funding for this program is provided by NASASSERVI-LPI Center for Lunar Science and Exploration with partialsupport from the Angel Ramos Visitor Center through UMET andmanagement by USRA

Author(s) Linda A Rodriguez-Ford Luisa Zambrano-Marin Bryan M Petty Elizabeth Sternke Andrew M Ortiz Edgard G Rivera-ValentinInstitution(s) 1 Arecibo Observatory

20208 ndash Promoting Diversity in STEM through ActiveRecruiting and Mentoring The Pre-Major inAstronomy Program (Pre-MAP) at the University ofWashingtonThe Pre-Major in Astronomy Program (Pre-MAP) is a research andmentoring program for underclassmen and transfer studentsoffered by the University of Washington Astronomy Departmentsince 2005 The primary goal of Pre-MAP is to recruit and retainstudents from groups traditionally underrepresented in sciencetechnology engineering and mathematics (STEM) through earlyexposure to research The Pre-MAP seminar is the core componentof the program and offers instruction in computing skills datamanipulation science writing statistical analysis and scientificspeaking and presentation skills Students choose research projectsproposed by faculty post-docs and graduate students in areasrelated to astrophysics planetary science and astrobiologyPre-MAP has been successful in retaining underrepresentedstudents in STEM fields relative to the broader UW population andweve found these students are more likely to graduate and excelacademically than their peers As of spring 2015 more than onehundred students have taken the Pre-MAP seminar and bothinternal and external evaluations have shown that all groups ofparticipating students report an increased interest in astronomyand science careers at the end of the seminar Several formerPre-MAP students have obtained or are pursuing doctoral andmasterrsquos degrees in STEM fields many more work at NASAcenters teaching colleges or as engineers or data analysts Pre-MAP student research has produced dozens of publications inpeer-reviewed research journals This talk will provide an overviewof the program the structure of the seminar examples of projectscompleted by students cohort-building activities outside theseminar funding sources recruitment strategies and the aggregatedemographic and achievement data of our students It is our hopethat similar programs may be adopted successfully at otherinstitutions

Author(s) Edward Schwieterman Breanna Binder Michael Tremmel Kristen Garofali Eric Agol VictoriaMeadowsInstitution(s) 1 University of Washington

20209 ndash Scientist-Educator Partnerships theCornerstone of Astrophysics EPOFor nearly two decades NASA has partnered scientists andeducators by embedding Education and Public Outreach (EPO)programs and funding in its science missions and researchactivities This enables scientist and educators to work side-by-sidein translating cutting-edge NASA science and technology forclassrooms museums and public venues

The Office of Public Outreach at the Space Telescope ScienceInstitute (STScI) is uniquely poised to foster collaboration betweenscientists with content expertise and educators with pedagogyexpertise As home to both Hubble Space Telescope and the futureJames Webb Space Telescope STScI leverages the expertise of itsscientists to create partnerships with its collocated Education Teamto translate cutting-edge NASA science into new and effective

learning tools In addition STScI is home of the NASA ScienceMission Directorate (SMD) Astrophysics Science EPO Forumwhich facilitates connections both within the SMD EPOcommunity and beyond to scientists and educators across all NASAAstrophysics missions These collaborations strengthenpartnerships build best practices and enhance coherence forNASA SMD-funded EPO missions and programs

We will present examples of astronomersrsquo engagement in our EPOefforts such as NASA Science4Girls

Author(s) Bonnie K Meinke Denise A Smith BrandonLawton Bonnie Eisenhamer Hussein JirdehInstitution(s) 1 STScI

203 ndash Centaurs Trans-Neptunian Objectsand the Inner Oort Cloud20301 ndash Rotational properties of the Haumea familymembers and candidates Short-term variabilityHaumea is one of the largest known Trans-Neptunian Objects(TNOs) with several anomalous characteristics It is a fast rotatorwith a double-peak period of 392 h Its spectrum is dominated bywater ice features and the high albedo suggests nearly pure waterice on the surface It has two known satellites and a family of atleast ten TNOs with very similar proper orbital parameters andspectral properties The formation of this peculiar family (Haumeaits two moons and dynamically related bodies) is not wellunderstood despite various models that have been proposed duringthe past few yearsIn order to improve our understanding of the formation of thisfamily we have examined the rotational properties of the familymembers and candidates (ie objects with similar proper orbitalelements to the family members but without water ice on theirsurface or without observations to detect surface water) We reportnew short-term variability for 5 family members and 7 candidatesfrom data collected over the past five years using multipleground-based facilities Thanks to our study all the Haumea familymembers have a short-term variability studyFrom rotational data assuming fluid-like rubble-pile structure weconstrain ellipsoidal axis ratios for individual objects and set alower limit to densities We also compared lightcurve amplitudeand rotational frequency distributions for the family memberscandidates and unrelated TNOs to search for additional clues tothe progenitor and the formation of this family

Author(s) Audrey Thirouin Scott S Sheppard Keith SNoll Nicholas A Moskovitz Alain Doressoundiram Institution(s) 1 DTM Carnegie Institution for Science 2 LESIA- Observatory of Paris 3 Lowell Observatory 4 NASA-GoddardSpace Flight Center

20302 ndash Near-Infrared and Optical colors of Trans-Neptunian Objects and Centaurs from Ground-BasedObservations in Support of Spitzer ObservationsTrans-Neptunian objects and Centaurs are small icy bodies locatedbeyond the orbit of Neptune and between the orbits of Neptuneand Jupiter respectively These objects are composed of organicmaterial of silicate minerals and of different ices including H OCH N and CH OH Determining the composition of such objectusually requires spectroscopic measurements on large telescopesHowever we can constrain the compositions of these objects bymeasuring their near-infrared colors that -- in combination withexisting data from the Spitzer Space Telescope -- can indicatesurface composition We will present near-infrared magnitudesand colors of at least 24 trans-Neptunian objects and 3 Centaursobtained in ground-based observations We observed with GeminiUKIRT and the 90 Bok Telescope on Kitt Peak between 2011 and2015 The combination of our data with existing Spitzer SpaceTelescope data enables us to identify spectral slope up to 45 μmand provides rough information on spectral bands which areimportant clues on the surface composition of our targets We willpresent preliminary results on the compositional analysis for select

11 1 1 1

1

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targets This work was supported by the Spitzer Science Center andNASAs Planetary Astronomy program

Author(s) Cassandra Lejoly Michael Mommert DavidTrilling Noemi Pinilla-Alonso Josh Emery Chad Melton Don McCarthy Craig KulesaInstitution(s) 1 Department of Astronomy - University ofArizona 2 Department of Earth and Planetary Science -University of Tennessee 3 Department of Physics and Astronomy- Northern Arizona University

20303 ndash The color-magnitude distribution of smallKuiper Belt objectsOccupying a vast region beyond the ice giants is an extensiveswarm of minor bodies known as the Kuiper Belt Enigmatic intheir formation composition and evolution these Kuiper Beltobjects (KBOs) lie at the intersection of many of the mostimportant topics in planetary science Improved instruments andlarge-scale surveys have revealed a complex dynamical picture ofthe Kuiper Belt Meanwhile photometric studies have indicatedthat small KBOs display a wide range of colors which may reflect achemically diverse initial accretion environment and provideimportant clues to constraining the surface compositions of theseobjects Notably some recent work has shown evidence forbimodality in the colors of non-cold classical KBOs which wouldhave major implications for the formation and subsequentevolution of the entire KBO population However these previouscolor measurements are few and mostly come from targetedobservations of known objects As a consequence the effect ofobservational biases cannot be readily removed preventing onefrom obtaining an accurate picture of the true color distribution ofthe KBOs as a wholeWe carried out a survey of KBOs using the Hyper Suprime-Caminstrument on the 82-meter Subaru telescope Our observingfields targeted regions away from the ecliptic plane so as to avoidcontamination from cold classical KBOs Each field was imaged inboth the grsquo and irsquo filters which allowed us to calculate the grsquo-irsquo colorof each detected object We detected more than 500 KBOs over twonights of observation with absolute magnitudes from H=6 toH=11 Our survey increases the number of KBOs fainter than H=8with known colors by more than an order of magnitude We findthat the distribution of colors demonstrates a robust bimodalityacross the entire observed range of KBO sizes from which we cancategorize individual objects into two color sub-populations -- thered and very-red KBOs We present the very first analysis of themagnitude distributions of the two color sub-populations

Author(s) Ian Wong Michael E BrownInstitution(s) 1 CALTECH

20304 ndash The Outer Solar System Origins Survey coldclassicals beyond the 21 resonanceWith the 85 characterised discoveries from the first quarter of theongoing Outer Solar System Origins Survey (OSSOS) withMegaPrime on the Canada-France-Hawaii Telescope we find thatthe CFEPS L7 model of Petit et al 2011 remains an accurateparameterization of the classical Kuiper belts orbital structure andthe population estimate for the main belt remains unchanged (for39 AU lt a lt 47 AU) We independently confirm the existence ofsubstructure within the main classical Kuiper belt The semi-majoraxis distribution of the stirred component of the cold classicalsmust contain a clumped lsquokernelrsquoWe detect an extension of the cold classical Kuiper belt thatcontinues at least several AU beyond the 21 mean motionresonance with Neptune This extension would have strongcosmogonic implications for the origin of the classical belts orbitalsubstructureWe will discuss how the 140 new objects we discovered in thesecond quarter of OSSOS place further constraints on coldclassicals beyond the 21 resonance Our 16-18 monthobservational arcs and improved astrometric technique continue toachieve extremely high-quality measurements of TNO orbitsfractional semimajor axis uncertainties of our discoveries areconsistently in the range 001-01 allowing rapid orbital

classification

Author(s) Michele T Bannister J J Kavelaars BrettGladman Jean- Marc Petit Stephen Gwyn Kathryn Volk Ying- Tung Chen Mike AlexandersenInstitution(s) 1 ASIAA 2 Institut UTINAM - UMR CNRS 3NRC Herzberg 4 University of Arizona 5 University of BritishColumbia 6 University of Victoria

20305 ndash Resonant Trans-Neptunian PopulationsConstraints from the first quarter of the Outer SolarSystem Origins SurveyThe first two observational sky blocks of the Outer Solar SystemOrigins Survey (OSSOS) have nearly doubled the set ofwell-characterized observed trans-Neptunian objects (TNOs) thatoccupy mean motion resonances with Neptune We describe the 31securely (plus 8 insecurely) resonant TNOs detected by OSSOS sofar and use them to independently verify the resonant populationmodels from the Canada France Ecliptic Plane Survey with whichwe find broad agreement One of the OSSOS blocks described hereis well-suited to detecting objects trapped at very low librationamplitudes in Neptunes 32 mean motion resonance a dynamicalpopulation of interest in testing the origins of resonant TNOs Wehave detected three plutinos (32 objects) with libration amplitudesless than 20 degrees which requires that plutino librationamplitude distribution be extended to lower values Using theOSSOS detections of 52 objects we confirm that this resonance ismore populated than predicted by models of the outer SolarSystems early dynamical history our minimum populationestimate shows that just the high eccentricity (egt035) portion ofthe resonance are at least as populous as the 21 resonance andpossibly as populated as the 32 resonance The OSSOS 21detections confirm that the 21 resonance has a dynamically colderinclination distribution than either the 32 or 52 resonancesUsing the combination of OSSOS and CFEPS detections of 21objects we constrain the fraction of 21 objects in the symmetricmode of libration to be 02--085 (the rest being asymmetric) wealso constrain the ratio of leading to trailing asymmetric librators (aratio that has been theoretically predicted to vary depending onNeptunes migration history) to be 005--08 at 95 confidenceThese constraints will be improved by future OSSOS blocks

Author(s) Kathryn Volk Ruth Murray-Clay BrettGladman Samantha Lawler Michele Bannister JJKavelaars Jean-Marc Petit Stephen Gwyn MikeAlexandersen Ying-Tung Chen Patryk Sofia Lykawka WingIp Hsing Wen LinInstitution(s) 1 Academia Sinica 2 Kinki University 3National Central University 4 NRC-Herzberg 5 Observatoire deBesancon Universite de Franche Comte 6 The University ofArizona 7 University of British Columbia 8 University ofCalifornia Santa Barbara 9 University of Victoria

20306D ndash Exploring the Outer Neptune ResonancesConstraints on Solar System EvolutionThe long-term evolution of objects in the outer n1 resonances withNeptune provide clues to the evolutionary history of the SolarSystem Based on 4 objects with semi-major axes near the 51resonance we estimate a substantial and previously unrecognizedpopulation of objects perhaps more significant than the populationin the 32 (Plutino) resonance These external resonances arelargely unexplored in both observations and dynamicalsimulations However understanding the characteristics andtrapping history for objects in these populations is critical forconstraining the dynamical history of the solar system The 4objects detected in the Canada-France Ecliptic Plane Survey(CFEPS) were classified using dynamical integrations Three areresonant and the fourth appears to be a resonance diffusionobject part of a population which exited the resonance throughchaotic diffusion The 3 resonant objects are taken to berepresentative of the resonant population so by using thesedetections and the CFEPS characterization (pointings anddetection limits) we calculate a population estimate for thisresonance at ~1900(+3300 -1400) objects with Hglt8 [Pike et al

3 33 2 2 3

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30

2015] This is at least as large as the Plutinos (32 resonance) at90 confidence The small number of detected objects results insuch a large population estimate due to the numerous biasesagainst detecting objects with semimajor axes at ~88AU Thedynamical behavior of the known objects suggests that thetrapping mechanism for the 51 resonance is resonance stickingfrom the scattering objects Based on our results from the 51resonance we have begun a project to examine the long termevolution of the other n1 resonances to determine the importanceof resonance diffusion and transfer between libration islandsamong the scattering-captured members of those populations

Author(s) Rosemary E Pike JJ Kavelaars Cory JShankman Jean-Marc Petit Gladman Brett Kat Volk MikeAlexandersenInstitution(s) 1 Institut UTINAM 2 Institute of Astronomy ampAstrophysics Academia Sinica 3 NRC Herzberg 4 University ofArizona 5 University of British Columbia 6 University ofVictoria

20307 ndash Searching for Extreme Kuiper Belt Objectsand Inner Oort Cloud ObjectsSince late 2012 we have been performing the largest and deepestsurvey for distant solar system objects In the nearly one thousandsquare degrees we have covered so far we have discovered theobject with the most distant perihelion known (2012 VP113)several extreme Kuiper Belt objects with moderate perihelia andlarge eccentricities one of the top ten intrinsically brightest Trans-Neptunian objects an ultra-wide Kuiper Belt binary one of themost distant known active comets and two active asteroids in themain belt of asteroids The Kuiper Belt population has an outeredge at about 50 AU Sedna and our recent discovery 2012 VP113are the only known objects with perihelia significantly beyond thisedge at about 80 AU These inner Oort cloud objects obtained theirorbits when the solar system was vastly different from now Thusthe dynamical and physical properties of objects in this region offerkey constraints on the formation and evolution of our solar systemWe will discuss the most recent results of our survey

Author(s) Scott S Sheppard Chad Trujillo Dave TholenInstitution(s) 1 Carnegie Inst of Washington 2 GeminiObservatory 3 University of Hawaii

20308 ndash Three steps toward understanding thedynamical structure of the Kuiper belt (and what itmeans for Neptunes migration)Much of the dynamical structure of the Kuiper belt can beexplained if Neptune migrated over several AU andor if Neptunewas scattered to an eccentric orbit during planetary instabilityStep 1 An outstanding problem with the previousmigrationinstability models is that the distribution of orbitalinclinations they predict is narrower than the one inferred fromobservations Here we perform numerical simulations of theKuiper belt formation starting from an initial state with Neptune at20lta_Nlt30 AU and a dynamically cold outer disk extending frombeyond a_N to 30 AU Neptunes orbit is migrated into the disk onan e-folding timescale 1 lt tau lt 100 Myr A small fraction of thedisk planetesimals become implanted into the Kuiper belt in thesimulations We find that the inclination constraint implies thatNeptunes migration was slow (tau gt 10 Myr) and long range (a_Nlt 25 AU)Step 2 A particularly puzzling and up-to-now unexplained featureof the Kuiper belt is the so-called `kernel a concentration of orbitswith semimajor axes a=44 AU eccentricities e=005 andinclinations ilt5 deg Here we show that the Kuiper belt kernel canbe explained if Neptunes migration was interrupted by adiscontinuous change of Neptunes semimajor axis when Neptunereached 28 AU (jumping-Neptune model)Step 3 The existing migrationinstability models invariably predictan excessively large resonant population while observations showthat the non-resonant orbits are in fact more common (egPlutinos in the 32 resonance represent only ~13 of the main beltpopulation) Here we show that the observed population statisticimplies that Neptunes migration was grainy as expected from

scattering encounters of Neptune with massive planetesimals Ourpreferred fit to observations suggests that the outer planetesimaldisk below 30 AU contained ~2000 bodies with mass comparableto that of PlutoTogether these results imply that Neptunes migration was slowlong-range and grainy and that Neptune radially jumped by ~05AU when it reached 28 AU This is consistent with Neptunesorbital evolution obtained in the recently developed models ofplanetary instabilitymigration (Nesvorny amp Morbidelli 2012 AJ144)

Author(s) David NesvornyInstitution(s) 1 SWRI

20309 ndash Into the Kuiper Belt New HorizonsPost-PlutoNew Horizons is now beyond Pluto and flying deeper into theKuiper Belt In the summer of 2014 a Hubble Space TelescopeLarge Program identified two candidate Cold Classical Kuiper BeltObjects (KBOs) that were within reach of New Horizons remainingfuel budget Here we present the selection of the Kuiper Belt flybytarget for New Horizons post-Pluto mission our state ofknowledge regarding this target and the potential 2019 flyby thestatus of New Horizons targeting maneuver and prospects fornear-future long-range observations of other KBOs

Author(s) Alex Harrison Parker John Spencer SusanBenecchi Richard Binzel David Borncamp Marc Buie Cesar Fuentes Stephen Gwyn JJ Kavelaars Keith Noll Jean-Marc Petit Simon Porter Mark Showalter S AlanStern Ray Sterner David Tholen Anne Verbiscer HalWeaver Amanda ZangariInstitution(s) 1 GSFC 2 IfA 3 JHU-APL 4 MIT 5 NAU 6NRC 7 Observatoire de Besancon 8 PSI 9 SETI Institute 10Southwest Research Institute 11 STScI 12 University of Virginia

204 ndash Asteroid Radar amp Thermal StudiesMicrowaved and Served Hot20401 ndash Thermal inertia of eclipsing binary asteroidsthe role of component shapeThermal inertia controls the temperature distribution on asteroidsurfaces This is of crucial importance to the Yarkovsky effect andfor the planning of spacecraft operations on or near the surfaceAdditionally thermal inertia is a sensitive indicator for regolithstructureA uniquely direct way of measuring thermal inertia is throughobservations of the thermal response to an eclipse in a binarysystem when one component shadows the other This method waspioneered by Mueller et al (2010) who observed eclipses in (617)Patroclus using Spitzer IRS Buie et al (2015) report observationsof a stellar occultation by Patroclus Their estimate for the systemsprojected size agrees well with the Spitzer result However theoccultation revealed that the components are much more oblatelyshaped than was assumed by Mueller et alThis prompted us to study the role of component shape in theanalysis of thermal eclipse data Conceivably the global shape canhave a significant impact on the shape and size of the eclipsed areaand therefore on its thermal emission So far this has not beenstudied in a systematic way Using Patroclus and the existingSpitzer data as our test case we vary the ellipsoidal componentshape and determine the resulting best-fit thermal inertia This willlead to an updated estimate of Patroclus thermal inertia alongwith a potentially more realistic estimate of its uncertainty Beyondthat our results will inform ongoing and future thermal studies ofother eclipsing binary asteroids

Author(s) Michael Mueller Marlies van de WeijgaertInstitution(s) 1 Kapteyn Astronomical Institute U Groningen

20402 ndash Modeling the thermal emission fromasteroid 3 Juno using ALMA observations and theKRC thermal model

6 36 1 5 4

2

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10 3 2 123 10

1 1

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Asteroid 3 Juno (hereafter referred to as Juno) discovered 1September 1804 is the 11th largest asteroid in the Main AsteroidBelt (MAB) Containing approximately 1 of the mass in the MAB[1] Juno is the second largest S-type [2]As part of the observations acquired from Atacama LargeMillimetersubmillimeter Array (ALMA) [3] 10 reconstructedimages at ~60kmpixel resolution were acquired of Juno [4] thatshowed significant deviations from the Standard Thermal Model(STM) [5] These deviations could be a result of surfacetopography albedo variations emissivity variations thermalinertia variations or any combinationThe KRC thermal model [6 7] which has been extensively used forMars [eg 8 9] and has been applied to Vesta [10] and Ceres [11]will be used to compare model thermal emission to that observedby ALMA at a wavelength of 133 mm [4] The 10 images acquiredover a four hour period captured ~55 of Junorsquos 721 hourrotation Variations in temperature as a function of local time willbe used to constrain the source of the thermal emission deviationsfrom the STMThis work is supported by the NASA Solar System ObservationsProgramReferences[1] Pitjeva E V (2005) Solar System Research 39(3) 176 [2] BaerJ and S R Chesley (2008) Celestial Mechanics and DynamicalAstronomy 100 27ndash42 [3] Wootten A et al (2015) IAU GeneralAssembly Meeting 29 2237199 [4] arXiv150302650 [astro-phEP] doi 1010882041-82058081L2 [5] Lebofsky LA etaal (1986) Icarus 68 239ndash251 [6] Kieffer H H et al (1977) JGeophys Res 82 4249ndash4291 [7] Kieffer Hugh H (2013)Journal of Geophysical Research Planets Volume 118 Issue 3 pp451-470 [8] Titus T N H H Kieffer and P N Christensen(2003) Science 299 1048ndash1051 [9] Fergason R L et al (2012)Space Sci Rev 170 739ndash773 doi101007s11214-012-9891-3 [10]Titus T N et al (2012) 43rd LPSC held March 19-23 2012 at TheWoodlands Texas LPI Contribution No 1659 id2851 [11] TitusT N (2015) Geophysical Research Letters 42(7) 2130-2136

Author(s) Timothy N Titus Jian-Yang Li Arielle Moullet Mark V SykesInstitution(s) 1 National Radio Astronomy Observatory 2Planetary Science Institute 3 US Geological Survey

20403 ndash Characterizing Asteroid Thermal Propertiesthrough the Laboratory Study of MeteoritesAsteroid thermal diffusivity is critical to understanding its thermalevolution and thermal inertia determines its behavior underYarkovsky effects These properties are both functions of thermalconductivity heat capacity and density Thermal conductivity andheat capacity both vary with temperature while thermalconductivity and density are strongly influenced by microporosityOur survey of low-temperature (175K) heat capacities includesmore than 130 meteorites supplemented by precisiontemperature-sensitive heat capacities for 6 individual samplesHeat capacities (175K) range from 350 JkgK for unweathered ironmeteorites to 530 JkgK with most chondrites between 480 and520 JkgK Heat capacities for unweathered ordinary chondritefalls are within 5 of theoretical models and as a function oftemperature fit a theoretical curve of C =A+BT+CT +DTbetween 77 and 300 K and are consistent with mineral databetween 20 and 300 K (Values for ABCD vary by meteoritetype)Thermal conductivities are strong functions of porosity and below90 K strong functions of temperature Laboratory measurementsof several meteorites indicate that between 90 and 300 K mostthermal conductivities vary little with temperature Below 90 Kthermal conductivity drops off strongly as temperature decreasesAbove 2 porosity and 90 K thermal conductivities correlatelinearly with the inverse of porosity Pore geometry and orientationalso affects thermal conductivity thermal conductivity differsnoticeably for the same meteorite sample depending on thedirection of heat flowGiven these relations and meteorite data thermal diffusivity andthermal inertia can be derived over a range of porosities andtemperatures for most asteroids We see that porosity greatlyinfluences both thermal diffusivity and thermal inertia Even as

little as 20 porosity can reduce thermal diffusivity by two ordersof magnitude from the nonporous case

Author(s) Robert J Macke Guy J Consolmagno Cyril POpeil Daniel T BrittInstitution(s) 1 Boston College 2 University of CentralFlorida 3 Vatican Observatory

20404 ndash The Spherical Brazil Nut Effect and itsSignificance to AsteroidsAsteroids are intriguing remnant objects from the early solarsystem They can inform us on how planets formed they couldpossibly impact the earth in the future and they likely containprecious metals for those reasons there will be future explorationand mining space missions to them Telescopic observations andspacecraft data have helped us understand basic properties such astheir size mass spin rate orbital elements and their surfaceproperties However their interior structures have remainedelusive In order to fully characterize the interiors of these bodiesseismic data will be necessary However we can infer their interiorstructures by combining several key factors that we know aboutthem 1) Past work has shown that asteroids between 150 m to 10km in size are rubble-piles that are a collection of particles heldtogether by gravity and possibly cohesion 2) Asteroid surfacesshow cratering that suggests that past impacts would haveseismically shaken these bodies 3) Spacecraft images show thatsome asteroids have large protruding boulders on their surfaces Arubble-pile object made of particles of different sizes and thatundergoes seismic shaking will experience granular flowSpecifically a size sorting effect known as the Brazil Nut Effect willlead larger particles to move towards the surface while smallerparticles will move downwards Previous work has suggested thatthis effect could possibly explain not only why there are largeboulders on the surfaces of some asteroids but also might suggestthat the interior particles of these bodies would be organized bysize Previous works have conducted computer simulations and labexperiments however all the particle configurations used havebeen either cylindrical or rectangular boxes In this work wepresent a spherical configuration of self-gravitating particles that isa better representation of asteroids Our results indicate that whilefriction is not necessary for the Brazil Nut Effect to take place itaids the sorting process after a certain energy threshold is metEven though we find that the outer layers of asteroids couldpossibly be size sorted the inner regions are likely mixed

Author(s) Viranga Perera Alan P Jackson Erik Asphaug Ronald-Louis BallouzInstitution(s) 1 Arizona State University 2 University ofMaryland

20405 ndash An Investigation of 2D Electrostatic DustLevitation about BennuElectrostatic dust levitation has been hypothesized to occur nearthe surface of asteroids due to the interaction of the solar windplasma and UV radiation with the asteroidsrsquo surfaces and theirnear-zero surficial gravity Dust levitation could provide amechanism to move regolith across the surface of an asteroid Ourpreliminary investigations have identified grains sizes and thealtitudes at which grains may levitate considering a semi-analytical1D plasma model However our initial semi-analytical plasmamodel was not well-suited to the complex terminator region wherethe surface transitions between positive (dominated byphotoemission) and negative (in the plasma wake) potentials Inthis analysis we use a new 2D treecode-based plasma simulation tomore accurately model the plasma environment about a simplifiedcircular cross-section of the asteroid Bennu We investigate thealtitudes and grain sizes where electrostatic levitation could occurat Bennu The improved plasma model will allow more accuratepredictions of dust levitation and deposition particularly in theterminator and wake regions that could not be characterized beearlier plasma models

3 2 12

p (-2) (-05)

3 31 2

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32

Author(s) Christine Hartzell Michael ZimmermanInstitution(s) 1 Johns Hopkins University Applied PhysicsLaboratory 2 University of Maryland

20406D ndash On physical properties of planetarysurfaces studied by modeling radar scatteringAfter decades of post-discovery characterization and orbitalrefinement of near-Earth objects using planetary radars extensiveliterature describing the radar scattering properties of variousobjects of the Solar System has become available At the same timethere is a shortage of work on what the observed values implyabout the physical properties of the planetary surfaces Our goal isto fill part of this gapWe investigate which physical properties of a planetary surface orsmall body affect the radar echo and how All of the work will becarried out by modeling electromagnetic scattering with theprimary focus in the backscattering direction As all models areonly simplifications of the real world it is necessary to study whichmodels are the best analogies to observations Moreover thenumber of scattering scenarios is near infinite but numericalresources are limited Due to the limitations of specific codesseveral different codes are usedThe simulations reveal in the backscattering direction polarizationenhancement at certain bands of sizes and refractive indices Bystudying spherical inhomogeneous particles we found that theelectric permittivity defines the phase shift caused by the scattererand hence the depolarizing capability of the scatterer By usinglarge irregular particles as the scatterers a systematic effect of theabsorption on the radar observables can be seen which leads to asemi-analytic novel form of the radar scattering laws By usingsmall (wavelength-scale) irregular particles as internal or externaldiffuse medium inside or on the surface of a very large particleradar scattering can be simulated very realistically The resultsmainly support the current understanding of the effects of thesurface geometry the electric permittivity and multiple scatteringWe also explain how the electric permittivity can affect the radaralbedo and circular-polarization ratio by phase shift andabsorption In addition we show that as the polarization is verysensitive to the scatterer geometry simplifications made in thechoice of the geometry can have unprecedented effects

Author(s) Anne Virkki Karri MuinonenInstitution(s) 1 University of Helsinki

20407 ndash Radar imaging of binary near-Earth asteroid(357439) 2004 BL86We report radar imaging of near-Earth asteroid 2004 BL86obtained at Goldstone Arecibo Green Bank and elements of theVery Long Baseline Array between 2015 January 26-31 2004 BL86approached within 00080 au on January 26 the closest knownapproach by any object with an absolute magnitude brighter than~19 until 2027 Prior to the encounter virtually nothing wasknown about its physical properties other than its absolutemagnitude of 19 which suggested a diameter within a factor of twoof 500 m 2004 BL86 was a very strong radar target that providedan outstanding opportunity for radar imaging and physicalcharacterization Delay-Doppler images with range resolutions asfine as 375 m placed thousands of pixels on the object andconfirmed photometric results reported by Pravec et al (2015CBET 4063) that 2004 BL86 is a binary system During theobservations the asteroid moved more than 90 deg and provided arange of viewing geometries The bandwidth was relatively narrowon Jan 26 reached a maximum on Jan 27 and then narrowed onJan 28 a progression indicating that the subradar latitude movedacross the equator during those days The images reveal a roundedprimary with an equatorial diameter of ~350 m evidence forridges possible boulders and a pronounced angular feature ~100m in diameter near one of the poles Images from Jan 26 show arcsof radar-bright pixels on the approaching and receding limbs thatextend well behind the trailing edge in the middle of the echo Thisis the delay-Doppler signature of an oblate shape seen at least a fewtens of degrees off the equator A rough estimate for the diameterof the secondary is ~70 m and its narrow bandwidth is consistentwith the 14-h orbital period reported by Pravec et al (2015) The

images are suitable for 3D shape pole orbit and mass estimationThe observations utilized new data taking equipment at GreenBank to receive X-band (8560 MHz 35 cm) transmissions fromthe 70 m DSS-14 facility and for the first time transmissions usinga new C-band (7190 MHz 42 cm) radar at the 34 m DSS-13antenna at the Goldstone complex

Author(s) Lance A M Benner Marina Brozovic Jon DGiorgini Patrick A Taylor Ellen S Howell Michael W Busch Michael C Nolan Joseph S Jao Clement G Lee H AlysonFord Frank D GhigoInstitution(s) 1 Arecibo Observatory 2 JPL 3 NRAO 4 SETIInstitute

20408 ndash Radar observations of near-Earth asteroid(436724) 2011 UW158 using the Arecibo Goldstoneand Green Bank TelescopesNear-Earth asteroid (436724) 2011 UW158 made a close approachto the Earth on 2015 July 19 at a distance of 0016 au (64 lunardistances) We observed it between July 13-26 using the AreciboS-band (2380 MHz 125 cm) radar the Goldstone X-band (8560MHz 35 cm) radar and the Green Bank Telescope (GBT) Arecibodelay-Doppler observations achieved range resolutions as fine as75 m At the GBT we used a newly installed radar backend torecord the radar echoes which improved signal-to-noise ratios(SNRs) two-fold relative to monostatic reception at the 70-mDSS-14 antenna at Goldstone The higher SNRs allowed us toobtain images with range resolutions comparable to those atArecibo that reveal the asteroidrsquos surface topography with greatdetail The visible extents of the asteroid in the radar imagessuggest an elongated object with dimensions of about 600 x 300 mThe shape of the object is angular with a facet on one side thatspans the entire length of the asteroid Three parallel radar-brightfeatures are visible when the asteroid is oriented broadside andmay represent ridges These features cause unusually largebrightness variations in the echo as the asteroid rotates There areother radar-bright regions that suggest small-scale (tens of meters)topography Repetition of the leading edge profiles in the imagesindicates a spin period of ~37 minutes which is consistent with theperiod that was previously reported using lightcurves (B Gary TLister H K Moon P Pravec and B D Warner pers comm)This spin period is unusually fast among asteroids its size andsuggests that the object has relatively high cohesive strength 2011UW158 has a relatively low delta-V for spacecraft missions and ison NASArsquos Near-Earth Object Human Accessible Targets Study list

Author(s) Shantanu P Naidu Lance A M Benner MarinaBrozovic Jon D Giorgini Joseph S Jao Michael W Busch Patrick A Taylor James E Richardson Edgard G Rivera-Valentin Linda A Ford Frank D Ghigo Adam Kobelski

Institution(s) 1 Arecibo Observatory 2 Jet PropulsionLaboratory California Institute of Technology 3 NRAO 4 SETIInstitute

20409 ndash Potentially Hazardous Asteroid (85989) 1999JD6 Radar Infrared and Lightcurve Observationsand a Preliminary Shape ModelWe report observations of potentially hazardous asteroid (85989)1999 JD6 which passed 0048 AU from Earth (19 lunar distances)during its close approach on July 25 2015 During eleven daysbetween July 15 and August 4 2015 we observed 1999 JD6 withthe Goldstone Solar System Radar and with Arecibo Observatorysplanetary radar including bistatic reception of some Goldstoneechoes at Green Bank We obtained delay-Doppler radar images ata wide range of latitudes with range resolutions varying from 75 to150 meters per pixel depending on the observing conditions Weacquired near-infrared spectra from the NASA InfraRed TelescopeFacility (IRTF) on two nights in July 2015 at wavelengths from075 to 50 microns showing JD6s thermal emission We alsoobtained optical lightcurves from Ondrejov Observatory (in 1999)Table Mountain Observatory (in 2000) and Palmer Divide Station(in 2015) Previous observers had suggested that 1999 JD6 wasmost likely an elongated object based on its large lightcurveamplitude of 12 magnitudes (Szabo et al 2001 Polishook and

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33

Brosch 2008 Warner 2014) The radar images reveal an elongatedpeanut-shaped object with two lobes separated by a sharpconcavity JD6s maximum diameter is about two kilometers andits larger lobe is approximately 50 longer than its smaller lobeThe larger lobe has a concavity on its end We will present moredetails on the shape and rotation state of 1999 JD6 as well as itssurface properties from optical and infrared data and thermalmodeling

Author(s) Sean E Marshall Ellen S Howell MarinaBrozović Patrick A Taylor Donald B Campbell Lance A MBenner Shantanu P Naidu Jon D Giorgini Joseph S Jao Clement G Lee James E Richardson Linda A Rodriguez-Ford Edgard G Rivera-Valentin Frank Ghigo AdamKobelski Michael W Busch Petr Pravec Brian D Warner Vishnu Reddy Michael D Hicks Jenna L Crowell Yanga RFernandez Ronald J Vervack Michael C Nolan ChristopherMagri Benjamin Sharkey Brandon BozekInstitution(s) 1 Arecibo Observatory 2 Astronomical InstituteAcademy of Sciences of the Czech Republic 3 Center for SolarSystem Studies 4 Cornell University 5 Jet PropulsionLaboratory 6 Johns Hopkins University Applied PhysicsLaboratory 7 Lunar and Planetary Laboratory University ofArizona 8 National Radio Astronomy Observatory 9 PlanetaryScience Institute 10 SETI Institute 11 University of CentralFlorida 12 University of Maine at Farmington 13 University ofMinnesota 14 University of Texas

205 ndash Titans Atmosphere20501 ndash Seasonal variations in Titanrsquos stratosphereobserved with CassiniCIRS after the northern springequinoxSince 2004 Cassini has made more than 110 Titan flybysobserving its atmosphere with instruments including the CassiniComposite InfraRed Spectrometer (CIRS) We know from CIRSobservations that the global dynamics drastically changed after thenorthern spring equinox that occurred in August 2009 ([1] [2][3] [4]) The pole-to-pole middle atmosphere dynamics (above100 km) experienced a global reversal in less than 2 years after theequinox [4] while the northern hemisphere was entering springThis new pattern with downwelling at the south pole resulted inenrichment of almost all molecules inside the southern polarvortex while a persistent enhancement due to the former northernwinter subsidence is still seen in the north pole region Accordingto General Circulation Model calculations this single circulationcell pattern should remain until 2025We will present new 2015 CIRS limb observations analysis We willshow that many species (C H HCN HC N C H C H CH CCH C H ) are now highly enriched near the south pole byfactors ~100 at 500 km compared to just a few years ago Suchlarge middle atmospheric enrichments were never observed beforeand are similar to in situ results from INMS at 1000 km [5]We will also show that the north pole displays for the first timesince the beginning of the Cassini mission a depletion of moleculargas mixing ratios at altitudes higher than 300 km while deeperlevels remains enriched compared to mid-latitude regionsReferences[1] Teanby N et al Nature 491 pp 733-735 2012[2] Achterberg et al DPS 46 abstract 10207Tucson 2014[3] Coustenis et al DPS 46 abstract 10246 Tucson 2014[4] Vinatier et al Icarus 250 95-115 2015[5] Cui et al Icarus 200 581-615 2009

Author(s) Sandrine Vinatier Bruno Beacutezard Nick Teanby Seacutebastien Lebonnois Richard Achterberg Nicolas Gorius Andrei Mamoutkine F Michael FlasarInstitution(s) 1 Laboratoire de Meacuteteacuteorologie Dynamique 2LESIA Obs de Paris-Meudon 3 NASA Goddard Space FlightCenter 4 School of Earth Science University of Bristol 5 TheCatholic University of America 6 University of Maryland

20502 ndash Post-equinox evolution of Titans

south-polar stratosphereSince northern spring equinox in mid-2009 Titans atmospherehas demonstrated dramatic changes in temperature (Achterberg etal 2014) composition (Teanby et al 2012 Vinatier et al 2015Coustenis et al 2015) and aerosolice distribution (de Kok et al2014 Jennings et al 2015 West et al 2015) Changes have beengreatest at the southern winter pole which continues to enterdeeper into Titans shadow following the 2009 equinoxObservational highlights include development of a south polarhot-spot nitrile ice clouds dense condensate clouds and extremetrace gas concentrationsHere we use recent infrared spectral limb observations byCassiniCIRS to determine the evolution of temperature andcomposition of the south polar region since equinox Ourobservations show that the south polar hot-spot initially observedfollowing equinox has now disappeared and been replaced byextremely low temperatures throughout the stratospheresuspected to be due to enhanced radiative cooling There alsoappears to be an unusual distribution of nitrile species whichsuggests trace gases are now escaping the newly formed wintervortex Thus providing clues to the underlying circulation The newobservations will be presented and implications for Titans polaratmospheric dynamics discussedAchterberg et al (2014) DPS46 10207 TucsonCoustenis et al (2015) Icarus (in press)de Kok et al (2014) Nature 514 65-67Jennings et al (2015) ApJL 804 L34Teanby et al (2012) Nature 491 732-735Vinatier et al (2015) Icarus 250 95-115West et al (2015) Icarus (in press)

Author(s) Nicholas A Teanby Sandrine Vinatier Remco deKok Conor A Nixon Patrick GJ IrwinInstitution(s) 1 AOPP Oxford University 2 LESIA-Observatoire de Paris 3 NASA Goddard Space Flight Center 4SRON Netherlands Institute for Space Research 5 University ofBristol

20503 ndash ALMA Spectroscopy of Titans AtmosphereFirst Detections of Vinyl Cyanide and AcetonitrileIsotopologuesStudies of Titans atmospheric chemistry provide a uniqueopportunity to explore the origin and evolution of complex organicmatter in primitive planetary atmospheres The Atacama LargeMillimetersubmillimeter Array (ALMA) is a powerful newtelescope well suited to the study of molecular emission fromTitans stratosphere and mesosphere Here we present early resultsfrom our ongoing study to exploit the large volume of Titan datataken using ALMA in Early Science Mode (during the period2012-2014) Combining data from multiple ALMA Band 6observations we obtained high-resolution mm-wave spectra withunprecedented sensitivity enabling the first detection of vinylcyanide (C H CN) in Titans atmosphere Initial estimates indicatea mesospheric abundance ratio with respect to ethyl cyanide(C H CN) of [C H CN][C H CN] = 031 In addition we reportthe first detections on Titan of the C and N-substitutedisotopologues of acetonitrile ( CH CN and CH C N) Radiativetransfer models and possible chemical formation pathways forthese molecules will be discussed

Author(s) Martin Cordiner Maureen Y Palmer Conor ANixon Steven B Charnley Michael J Mumma Pat G J Irwin Nick A Teanby Zbigniew Kisiel Joseph SeriganoInstitution(s) 1 NASA Goddard Space Flight Center 2 PolishAcademy of Sciences 3 St Olaf College 4 University of Bristol 5University of Oxford

20504 ndash Observations of CO in Titans AtmosphereUsing ALMAThe advent of the Atacama Large Millimetersubmillimeter Array(ALMA) has provided a powerful facility for probing theatmospheres of solar system targets at long wavelengths (84-720GHz) where the rotational lines of small polar molecules areprominent In the dense nitrogen-dominated atmosphere of Titan

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photodissociation of molecular nitrogen and methane leads to awealth of complex hydrocarbons and nitriles in small abundancesPast millimetersubmillimeter observations includingground-based observations as well as those by the CompositeInfrared Spectrometer (CIRS) aboard the Cassini spacecraft haveproven the significance of this wavelength region for the derivationof vertical mixing profiles latitudinal and seasonal variations andmolecular detections Previous ALMA studies of Titan havepresented mapping and vertical column densities of hydrogenisocyanide (HNC) and cyanoacetylene (HC N) (Cordiner et al2014) as well as the first spectroscopic detection of ethyl cyanide(C H CN) in Titanrsquos atmosphere (Cordiner et al 2015)Here we report several submillimetric observations of carbonmonoxide (CO) and its isotopologues CO C O and C O inTitanrsquos atmosphere obtained with flux calibration data from theALMA Science Archive We employ NEMESIS a line-by-lineradiative transfer code to determine the stratospheric abundancesof these molecules The abundance of CO in Titans atmosphere isdetermined to be approximately 50plusmn1 ppm constant with altitudeand isotopic ratios are determined to be approximately C C =90 O O = 470 and O O = 2800 This report presents thefirst spectroscopic detection of C O in the outer solar systemdetected at gt11σ confidence This talk will focus on isotopic ratiosin CO in Titans atmosphere and will compare our results topreviously measured values for Titan and other bodies in the SolarSystem General implications for the history of Titan frommeasurements of CO and its isotopologues will be discussed

Author(s) Joseph Serigano Conor A Nixon MartinCordiner Patrick G J Irwin Nicholas Teanby Steven BCharnley Johan E Lindberg Anthony J RemijanInstitution(s) 1 Johns Hopkins University 2 NASA GoddardSpace Flight Center 3 National Radio Astronomy Observatory 4Oxford University 5 University of Bristol

20505 ndash Search for methane isotope fractionation dueto Rayleigh distillation on TitanKinetic fractionation of methane isotopes on Titan may bediagnostic of the temperatures where methane is evaporating fromthe surface and condensing in the atmosphere We describe theequilibrium fractionation that is expected to result in a depletion ofCH D in the gas and speculate about the magnitude of thisdepletion We search for spatial variation in CH D using near-IRspectra obtained with Keck NIRSPAO (Aacutedaacutemkovics et al 2015)and describe some limitations of the current methane lineassignments near 155μm in HITRAN2012 After performing arudimentary empirical correction to our radiative transfer modelwe perform retrievals of the CH D abundance Preliminary resultsfrom this work suggest that CH DCH is globally uniform towithin ~10 that is variation in CH D abundance of more than10 of the nominal value would be detectable in our existingobservations Improvements to both the observations and modelsare suggested and we discuss the limitations of our methodology

Author(s) Mate Adamkovics Jonathan L MitchellInstitution(s) 1 University of California 2 University ofCalifornia

20506 ndash Titan Aerosol Formation as a Sink for StableCarbon and Nitrogen IsotopesStable isotope ratios of major elements can be used to infer muchabout local- and global-scale processes on a planet On Titanaerosol production is a significant sink of carbon and nitrogen inthe atmosphere and isotopic fractionation of these elements maybe introduced during the advanced organic chemistry that leads tothe condensed phase products Several stable isotope pairsincluding C C and N N have been measured in situ orprobed spectroscopically by Cassini-borne instruments spacetelescopes or through ground-based observations However theeffect of a potentially critical pathway for isotopic fractionation ndashorganic aerosol formation and subsequent deposition onto thesurface of Titan ndash has not been considered due to insufficient dataregarding fractionation during aerosol formation To betterunderstand the nature of this process we have measured the

isotopic fractionation associated with the formation of Titanaerosol analogs via far-UV irradiation of several methane (CH )and nitrogen (N ) mixturesOur initial results probed the fractionation of the aerosol productrelative to the reactant gases as a function of CH abundance [1]Our results show that the direction of carbon isotope fractionationduring aerosol formation is in contrast to the expected result if thesource of the fractionation is a kinetic isotope effect The resultantfractionation in nitrogen favored the light ( N) isotope in theaerosol with NC ratios varying from 013 ndash 031 Ongoing workincludes probing the effects of pressure and temperature on thedirection and magnitude of the stable isotope fractionation We willpresent results alongside interpretation of the driving processes aswell as implications for Titan if similar fractionation occurredduring aerosol formation in the atmosphere[1] Sebree JA Stern JC Mandt KE Domagal-Goldman SDand Trainer MG C and N Fractionation of CH N Mixturesduring Photochemical Aerosol Formation Relevance to TitanIcarus in press 2015 doi101016jicarus201504016

Author(s) Melissa G Trainer Jennifer C Stern Joshua ASebree Thomas J Gautier Javier A Fuentes Shawn DDomagal-Goldman Kathleen E MandtInstitution(s) 1 NASA Goddard Space Flight Center 2Southwest Research Institute 3 University of Northern Iowa

20507 ndash New results from the analyses of the solidphase of the NASA Ames Titan Haze Simulation (THS)experimentIn Titanrsquos atmosphere a complex chemistry occurs at lowtemperature between N and CH that leads to the production ofheavy organic molecules and subsequently solid aerosols TheTitan Haze Simulation (THS) experiment was developed at theNASA Ames COSmIC facility to study Titanrsquos atmosphericchemistry at low temperature In the THS the chemistry issimulated by plasma in the stream of a supersonic expansion Withthis unique design the gas is cooled to Titan-like temperature(~150K) before inducing the chemistry by plasma and remains atlow temperature in the plasma (~200K) Different N -CH -basedgas mixtures can be injected in the plasma with or without theaddition of heavier molecules in order to monitor the evolution ofthe chemical growthFollowing a recent in situ mass spectrometry study of the gas phasethat demonstrated that the THS is a unique tool to probe the firstand intermediate steps of Titanrsquos atmospheric chemistry at lowtemperature (Sciamma-OrsquoBrien et al Icarus 243 325 (2014)) wehave performed a complementary study of the solid phase Thefindings are consistent with the chemical growth evolutionobserved in the gas phase Grains and aggregates form in the gasphase and can be jet deposited onto various substrates for ex situanalyses Scanning Electron Microscopy images show that morecomplex mixtures produce larger aggregates and that differentgrowth mechanisms seem to occur depending on the gas mixtureThey also allow the determination of the size distribution of theTHS solid grains A Direct Analysis in Real Time mass spectrometryanalysis coupled with Collision Induced Dissociation has detectedthe presence of aminoacetonitrile a precursor of glycine in theTHS aerosols X-ray Absorption Near Edge Structure (XANES)measurements also show the presence of imine and nitrilefunctional groups showing evidence of nitrogen chemistryInfrared and microIR spectra of samples deposited on KBr and Sisubstrates show the presence of more aromatic functional groupsfor more complex gas mixtures and allowed the determination ofthe samplesrsquo thickness These complementary studies show thepotential of THS to better understand Titanrsquos chemistry and theorigin of aerosol formation

Author(s) Ella Sciamma-OBrien Kathleen T Upton Jesse L Beauchamp Farid SalamaInstitution(s) 1 NASA Ames Research Center 2 NoyesLaboratory of Chemical Physics and the Beckman Institute -Caltech

20508 ndash Aerosol properties in Titans upper

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17

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atmosphere from UVIS airglow observationsMultiple Cassini observations reveal that the abundant aerosolparticles in Titans atmosphere are formed at high altitudesparticularly in the thermosphere [1] They subsequently falltowards the lower atmosphere and in their path their size shapeand population change in reflection to the variable atmosphericconditionsAlthough multiple observations can help us retrieve informationfor the aerosol properties in the lower atmosphere [2] we havelimited knowledge for their properties in the altitude range betweentheir formation region in the thermosphere and the upper regionof the main haze layer UVIS is one of a few instruments that canprobe this part of the atmosphere and allow for the retrieval of theaerosol propertiesHere we analyze observations of atmospheric airglow thatdemonstrate the signature of N emissions and light scatteringfrom aerosol particles at different altitudes above 500 km [3] Wefit these observations with a combined model of N airglow [4] andatmospheric scattering by gases and aerosols that allows us toseparate the pure scattering component and retrieve the aerosolsize (distribution) and density We particularly focus onobservations from the T32 flyby that probed high southernlatitudes in 2007 and combine good altitude resolution with highsignal to noise ratio We combine these with observations atdifferent phase angles and observing geometry conditions (nadirvs limb) in order to set better constraints on the aerosol propertiesOur preliminary results demonstrate an increase in the averageparticle size with decreasing altitude in the atmosphere from about10 nm at 800 km to ~50 nm at 500 km and an extinction profile at185 nm wavelength similar to the profile derive from UVISoccultation measurements at lower latitudes [5][1] Lavvas et al 2013 PNAS doi101073pnas1217059110 andreferences therein[2] Tomasko et al 2008 PSS 56 p669 Bellucci et al 2009 Icarus201 p198[3] Ajello et al 2008 GRL 35 L06102[4] Lavvas et al 2015 Icarus 260 p29[5] Koskinen et al 2011 Icarus 216 p507

Author(s) Panayotis Lavvas Tommi Koskinen EmilieRoyer Pascal Rannou Robert A WestInstitution(s) 1 GSMA 2 GSMACNRS 3 JPL 4 LASP 5University of Arizona

20509 ndash Retrievals of Aerosol and HydrocarbonAbundances in the Atmosphere of Titan from CassiniUVIS Stellar Occultation MeasurementsWe present retrievals of haze optical properties and hydrocarbonabundances in the atmosphere of Titan from Cassini UVIS stellaroccultation observations of the upper atmosphere above 300 kmThese measurements focus on the extinction in the far ultraviolet(FUV) wavelengths between 140 and 190 nm and include data frommultiple Titan flybys across several latitudes and longitudesCoherent structures in the optical depth profile are seen to vary bytens of kilometers in altitude across different latitudes while alsovarying temporally on time scales of months and yearsComparisons of these extinction estimates with the results of ouraerosol microphysics model suggest that processes aside fromsedimentation diffusional transport and Brownian coagulation aretaking place The UVIS spectrographs also provide measurement ofthe scattered solar spectrum which can be used to calculate thereal part of the aerosol index of refraction At the same time thephase angle distribution and absolute flux of the scatteredspectrum in combination with the extinction can be used toestimate other physical properties of the scattering particles Thusour results provide valuable constraints for models of Titanphotochemistry and haze formation throughout this region of theupper atmosphere

Author(s) Siteng Fan Joshua A Kammer Peter Gao Mao-Chang Liang Donald E Shemansky Yuk L YungInstitution(s) 1 Division of Geological and Planetary SciencesCalifornia Institute of Technology 2 Planetary and Space ScienceDivision Space Environment Technologies 3 Research Center forEnvironmental Changes Academia Sinica 4 Southwest ResearchInstitute

207 ndash Harold C Urey Prize No Photon LeftBehind How Modern Spectroscopy isTransforming Planetary Sciences GeronimoVillanueva (NASA Goddard Space FlightCenter)20701 ndash No photon left behind How modernspectroscopy is transforming planetary sciencesThe advent of sensitive high-resolution spectrometers and modernanalytical spectroscopic tools is opening new windows in theexploration of planetary atmospheres High-resolution infraredspectrometers with broad spectral coverage at ground-basedobservatories (eg Keck IRTF VLT) and arrays of radio telescopeswith state of the art receivers (eg ALMA) now permit theexploration of the kinematics composition and thermal structureof a broad range of planetary sources with unprecedentedprecision These combined with the advent of comprehensivespectroscopic databases containing billions of lines robustradiative transfer models and unprecedented availablecomputational power are transforming the way we investigateplanetary atmospheresSuch advances have allowed us to obtain the first mapping of waterDH on Mars (Villanueva et al 2015) to obtain one of the mostcomprehensive searches for organics in the Martian atmosphere(Villanueva et al 2013) and to obtain the first measurement ofwater DH of a periodic comet (Villanueva et al 2009)In this talk I will present the current frontiers in the exploration ofplanetary atmospheres and how the synergies between futurespace (eg ExoMars 2016 JWST) and ground astronomical assets(eg TMT E-ELT) will transform our understanding of thecomposition stability and evolution of the atmospheres in theSolar System and beyondVillanueva GL et al 2009 Astrophys J Lett 690 (1) pp L5ndashL9Villanueva GL et al 2013 Icarus 223 (1) pp 11ndash27Villanueva GL et al 2015 Science 348 (6) pp 218ndash221

Author(s) Geronimo Luis VillanuevaInstitution(s) 1 NASA - Goddard Space Flight Center

208 ndash Changing Perspectives on Mercuryand the Moon Brett Denevi (Johns HopkinsAPL)20801 ndash Changing Perspectives on Mercury and theMoonAirless cratered and not so different in size the Moon andMercury form a natural pair in the inner Solar System For decadesafter the 1974 and 1975 Mariner 10 flybys of Mercury with littlecompositional information no concrete evidence for volcanismand images of less than half of the planet it was thought thatMercuryrsquos surface may be similar to the lunar highlands an ancientanorthositic flotation crust subsequently shaped mainly by impactcratering However observations from the recently completedMESSENGER mission to Mercury have upended our view of theinnermost planet revealing for example a crust that may be richin graphite and that has been extensively resurfaced by volcanicactivity and geologic activity that may continue today to produceenigmatic ldquohollowsrdquo ndash a crust very different from that of the MoonMeanwhile the Moon has undergone its own revolution as datafrom recent spacecraft such as the Lunar Reconnaissance Orbiterreveal sites of silicic volcanism indicative of complex differentiation

2

2

2 54 1 3

1 4 13 2 1

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36

in the mantle tectonic activity that may be ongoing recent volcanicactivity that alters the paradigm that volcanism died on the Moonover a billion years ago and evidence that the early chronology ofthe inner Solar System may not be as well known as once thoughtAs our views of these two bodies evolve a new understanding oftheir differences informs our knowledge of the variety of processesand styles of planetary evolution and their similarities point tocommonalities among all airless bodies

Author(s) Brett W DeneviInstitution(s) 1 Johns Hopkins University Applied PhysicsLaboratory

209 ndash Vesta and Ceres by the Light of DawnChristopher Russell (UC Los Angeles)20901 ndash Vesta and Ceres by the light of DawnCeres and Vesta are the most massive bodies in the main asteroidbelt They both appear to be intact protoplanets whose growth mayhave been drastically altered by the concomitant formation ofJupiter These two bodies have witnessed 46 Ga of solar systemhistory much but not all of which has been recorded in theirsurfaces Dawnrsquos objective is to interview these two witnesses tolearn as much as possible about the early epoch These bodies areprotoplanets our best archetypes of the early building blocks of theterrestrial planets In particular siderophile elements in the Earthrsquoscore were probably first segregated in Vesta-like bodies and itswater was likely first condensed in Ceres-like bodiesMany of the basaltic achondrites originated from a common parentbody Dawn verified that Vesta was consistent with that parentbody hence strengthening geochemical inferences from thesesamples on the formation and evolution of the solar system andsupporting hypotheses for their delivery from Vesta to Earth Cereshas not revealed itself with a meteoritic record While the surface isscarred with craters it is probable that the ejecta from the crater-forming event created little competent material from the icy crustand any such ejected projectiles that reached Earth might havedisintegrated upon entry into the Earthrsquos atmosphereCeresrsquo surface differs greatly from Vestarsquos Plastic or fluidized masswasting is apparent as are many irregularly shaped cratersincluding many polygonal crater forms There are many central-pitcraters possibly caused by volatilization of the crust in the center ofthe impact There are also many central-peak craters which weremade by rebound or pingo-like formation processes Brightdeposits dot the landscape which are possibly salt-rich suggestingfluvial activity beneath the crust Observations of the brightestspots on Ceres could suggest sublimation from the surface of thebright area which may be water vapor driven as Herschelobservations suggest Ceres is not only the most massive body inthe asteroid belt but also possibly the most active

Author(s) Christopher T RussellInstitution(s) 1 UC Los Angeles

210 ndash Pluto System21001 ndash New Horizons disk-integrated approachphotometry of Pluto and CharonApproach and cruise observations of Pluto and Charon by NASAsNew Horizons LOng Range Reconnaissance Imager (LORRI)allow monitoring of Pluto not only at phase angles beyond Earths2 degree limit but present a near constant sub-observer latitude of43 degrees However the creation of light curves and solar phasecurves of the pair prove to be an interesting challenge Early imagesof the pair from July 2013 are barely resolved and have low signalwhile later images show the pair clearly resolved and at sufficientresolution Just at the Pluto approaches the signal level and imagequality of prior HST images surface features become resolvedrendering disk integrated photometry increasingly difficult andinaccurate with the largest discrepancies found at longitudeswhich show the intersection of features informally namedTombaugh Regio (the heart) and Cthulhu Macula (the whale)

Now post flyby accurate knowledge of the radius and the shapesof surface features and their patterns of dark and light allow for thecreation of custom PSFs created from flyby maps Using thesemaps we present disk-integrated approach photometry a solarphase curve and estimate Hapke parameters taking into accountthe sub-observer positionThis work was supported by the NASA New Horizons Project

Author(s) Amanda M Zangari Marc W Buie Bonnie JBuratti Anne J Verbiscer C J A Howett H A Weaver Catherine B Olkin Kimberly Ennico Leslie A Young S ASternInstitution(s) 1 Jet Propulsion Laboratory California Inst ofTechnology 2 Johns Hopkins University Applied PhysicsLaboratory 3 NASA Ames Research Center 4 SwRI 5University of Virginia

21002 ndash On the Departure from Isothermality ofPlutos Volatile Ice due to Local Insolation andTopographyPlutorsquos atmosphere is known to be supported by the vapor pressureof ices that are volatile at low temperature primarily N andsecondarily CH and CO The atmospheric bulk is regulated by theglobally average temperature of the ice which is determined by aradiative balance between the diurnally average insolationabsorbed globally by the volatile ice and the global volatile icethermal radiation This bulk is sufficient that Plutorsquos atmosphere isclose to hydrostatic equilibrium though this may not remain so asPluto continues to move towards aphelion With the weight of theatmosphere currently distributed evenly around the body the icetemperature is expected to be globally isothermal in absence oftopographic variations due to the transport of latent heat fromregions of high insolation to low insolation through sublimationand condensation Images returned from the New Horizonsspacecraft show topographical features including mountain rangesthat extend above 35 km with albedo variations that suggest atopographical dimension or dependence of the volatile ice depositsIn general the conditions often applied to a volatile atmosphere ofhydrostatic equilibrium and vapor-solid phase equilibrium areapproximations that may not always both be appropriate This isparticularly the case in the presence of topography when theatmospheric lapse rate differs from the wet adiabat We present ourresults of an investigation of the effect of variable insolation andtopography on Plutorsquos local ice temperature assuming anatmosphere close to hydrostatic equilibrium

Author(s) Laurence M Trafton John A StansberryInstitution(s) 1 Space Telescope Science Institute 2 Univ ofTexas at Austin

21003 ndash New Horizons and Hubble Space TelescopePhotometry of Nix and HydraNew Horizons has provided the first spatially-resolved images ofPlutorsquos small satellites enabling the characterization of albedo andscattering properties across their surface Application ofphotometric models to yield the physical properties of airlessplanetary surfaces requires observations spanning the broadestpossible range of viewing and illumination geometries from fulldisk to thin crescent While New Horizons observed the Plutosystem at phase angles no smaller than 15deg full-disk Hubble SpaceTelescope images (HST Program 13367 M Buie PI) at phaseangles between 006deg and 17deg constrain the phase function nearopposition Together with New Horizons disk-resolved images weuse the near-opposition phase function to test whether ejectaexchange (Stern 2009 Icarus 199 571) affects photometricproperties With direct measurements of small satellite sizes fromNew Horizons we can determine the disk-integrated geometricalbedo by extrapolating the HST observations to zero phase NewHorizons observations at larger phase angles reveal surfaceroughness and directional scattering properties Finally we placethe photometric properties of Plutorsquos small satellites in context withthose of similar size in other planetary systems This work wassupported in part by the NASA New Horizons Project

1

1

4 41 5 4 2

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Author(s) Anne J Verbiscer Marc W Buie Richard PBinzel Marina Brozovic Kimberly Ennico William MGrundy Robert Jacobson Cathy B Olkin Mark R Showalter John R Spencer Sol Alan Stern Hal A Weaver Leslie AYoungInstitution(s) 1 Jet Propulsion Laboratory 2 Johns HopkinsUniversity Applied Physics Laboratory 3 Lowell Observatory 4Massachusetts Institute of Technology 5 NASA Ames ResearchCenter 6 SETI Institute 7 Southwest Research Institute 8University of Virginia

21004 ndash Long Wavelength Observations of ThermalEmission from Pluto and Charon with ALMALong wavelength observations of Pluto can determine atmospherictemperatures abundances and vertical distributions for thosemolecules that have transitions at these wavelengths In additionobservations of both Pluto and Charon can elucidate their surfaceand subsurface temperatures and surface compositions (anddistribution with enough resolution) We have used the AtacamaLarge Millimeter Array (ALMA) to observe the CO and HCN in theatmosphere of Pluto and to observe thermal emission from thetwo bodies where the resolution is enough to separate them (butnot enough to resolve each individually) We report here on thethermal emission observations and separately at this meeting onthe CO [1] and HCN [2] observations We observed thePlutoCharon system with ALMA on June 12 and 13 2015 at awavelength of ~086 mm Both days provide separate observationsof the thermal emission from Pluto and Charon We find apreliminary value of the brightness temperature of the two bodiesof 35 K and 46 K with variation of less than 1 K between the twodays and SNR of gt 300 for Pluto and gt 100 for Charon This issimilar to previous observations of the separate thermal emissionof the two bodies with the Submillimeter Array (SMA) [3] and VeryLarge Array (VLA) [4] We will discuss the implications of thesemeasured brightness temperatures and the apparent lack ofsignificant variation between the two days (longitudes)[1] Gurwell et al this meeting [2] Lellouch et al this meeting [3]Gurwell amp Butler BAAS 37 2005 [4] Butler et al BAAS 43 2010

Author(s) Bryan J Butler Mark Gurwell EmmanuelLellouch Arielle Moullet Raphael Moreno DominiqueBockelee-Morvan Nicolas Biver Thierry Fouchet Darek Lis Alan Stern Leslie Young Eliot Young Hal Weaver JeremieBoissier John StansberryInstitution(s) 1 Institut de Radio-Astronomie Millimeacutetrique 2Caltech 3 Harvard-Smithsonian Center For Astrophysics 4 JHUAPL 5 NRAO 6 Observatoire de Paris 7 STScI 8 SWRI

21005 ndash The Radii and Oblateness of Pluto andCharon Preliminary Results from the 2015 NewHorizons FlybyWe present preliminary results for the radii and oblateness of Plutoand Charon Accurate determinations of the mean radii of Plutoand Charon are important for establishing their densities and bulkcomposition A fossil bulge if present would place constraints onthe thermal and orbital evolution of these bodies [12] The NewHorizons LORRI imaging system [3] has provided global images ofPluto and Charon with best resolutions of 38 and 23 kmpixrespectively Three separate approaches have been used todetermine mean radii and oblateness from the images two using athreshold DN value [45] and one using a maximum gradientmethod These approaches were validated using synthetic imageshaving a range of photometric functions Tradeoffs between thelimb center location and the derived shape in individual images canbe reduced by combining limb pixel locations obtained fromdifferent imaged rotational phasesThis work was supported by NASAs New Horizons project[1] Robuchon amp Nimmo Icarus 216 426 2011 [2] McKinnon ampSinger DPS 46 abs no 41907 2014 [3] Cheng et al SSR 140189 2008 [4] Dermott amp Thomas Icarus 73 25 1988 [5]Thomason amp Nimmo LPSC 46 abs no 1462 2015

Author(s) Carey M Lisse Francis Nimmo William BMcKinnon Orkan M Umurhan Marc W Buie Tod R Lauer James H Roberts S Alan Stern Hal A Weaver Leslie AYoung Kimberly Ennico-Smith Cathy B OlkinInstitution(s) 1 Johns Hopkins Univ Applied Physics Lab 2NASA ARC 3 NOAO 4 SwRI 5 UCSC 6 WashingtonUniversity St Louis

21006 ndash Geomorphological Mapping of SputnikPlanum and Surrounding Terrain on PlutoThe New Horizons flyby of Pluto in July 2015 has provided the firstfew close-up images of the Kuiper belt object which reveal it tohave a highly diverse range of terrains implying a complexgeological history The highest resolution images that have yetbeen returned are seven lossy 400 mpixel frames that cover themajority of the prominent Plutonian feature informally namedSputnik Planum (all feature names are currently informal) and itssurroundings This resolution is sufficient to allow detailedgeomorphological mapping of this area to commence Losslessversions of all 15 frames that make up the mosaic will be returnedin September 2015 and the map presented at DPS will incorporatethe total area covered by these framesSputnik Planum with an area of ~650000 km is notable for itssmooth appearance and apparent total lack of impact craters at 400mpixel resolution The Planum actually displays a wide variety oftextures across its expanse which includes smooth and pittedplains to the south polygonal terrain at its center (the polygons canreach tens of kilometers in size and are bounded by troughs thatsometimes feature central ridges) and to the north darkerpolygonal terrain displaying patterns indicative of glacial flowWithin these plains there exist several well-defined outcrops of amottled lightdark unit that reach from several to tens ofkilometers across Separating Sputnik Planum from the darkcratered equatorial terrain of Cthulhu Regio on its south-westernmargin is a unit of chaotically arranged mountains (HillaryMontes) similar mountainous units exist on the south andwestern margins The northern margin is bounded by rugged hillycratered terrain (Cousteau Rupes) into which ice of SputnikPlanum appears to be intruding in places Terrain of similar reliefexists to the east but is much brighter than that to the north Thesouthernmost extent of the mosaic features a unit of roughundulating terrain (Pandemonium Dorsa) that displays very fewimpact craters at 400 mpixel resolutionThis work was supported by the NASA New Horizons project

Author(s) Oliver White Alan Stern Hal Weaver CathyOlkin Kimberly Ennico Leslie Young Jeff MooreInstitution(s) 1 NASA Ames Research Center 2 SouthwestResearch Institute 3 The Johns Hopkins University AppliedPhysics Laboratory

21007 ndash Probing Plutos Underworld Predicted IceTemperatures from Microwave RadiometryDecoupled from Surface ConditionsThe Pluto dwarf planet has been successfully observed in July 2015by the New Horizons spacecraft (NASA) during a close-targetedflyby which reavealed surprising and fascinating landscapes Whiledata are still being downlinked on the ground we propose topresent a prediction of the observation of the Radio ScienceExperiment experiment (REX) that occured on July 14 2015 andaimed at measuring the microwave brightness temperature ofPlutorsquos night sidePresent models admit a wide range of 2015 surface conditions atPluto and Charon where the atmospheric pressure may undergodramatic seasonal variation and for which measurements havebeen performed by the New Horizons mission One anticipatedobservation is the microwave brightness temperature heretoforeanticipated as indicating surface conditions relevant to surface-atmosphere equilibrium However drawing on recent experiencewith Cassini observations at Iapetus and Titan we call attention tothe large electrical skin depth of outer solar system materials suchas methane nitrogen or water ice such that this observation mayindicate temperatures averaged over depths of several or tens ofmeters beneath the surface

8 74 1 5

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5 36 5 6

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38

Using a seasonally-forced thermal model to determine microwaveemission we predict that the southern hemisphere observations (inthe polar night in July 2015) of New Horizons should displayrelatively warm effective temperatures of about 40 K This wouldreflect the deep heat buried over the last century of summer evenif the atmospheric pressure suggests that the surface nitrogen frostpoint may be much lower We will present our predictions anddiscuss their impact for the interpretation of the REXmeasurements

Author(s) Alice Le Gall Ralph Lorenz Cedric LeyratInstitution(s) 1 APL 2 LATMOS 3 LESIA

21008 ndash The visible spectrum of Pluto secular andlongitudinal variationContinuous near-infrared spectroscopic observations during thelast 30 years enabled the characterization of the Plutos surface andthe study of its variability Nevertheless only few data are availablein the visible range where the nature of the complex-organics canbe studiedFor this reason we started an observational campaign to obtain thePlutos relative reflectance in the visible range with the aim ofcharacterizing the different components of its surface andproviding ground based observations in support of the NewHorizons mission We observed Pluto on six nights in 2014 withthe imagerspectrograph ACAMWHT (La Palma Spain) Weobtained six spectra in the 040 ndash 093 microm range that covered awhole Plutos rotational period (64 days)To study longitudinal variations we computed for all the spectrathe spectral slope and the position and the depth of the methaneice absorption bands Also to search for secular or seasonalvariations we compared our data with previously published resultsAll the spectra present a red slope indicating the presence ofcomplex organics on Plutos surface and show the methane iceabsorption bands between 073 and 090 μm We also report thedetection of the CH absorption band at 062 μm already detectedin the spectra of Makemake and Eris The measurement of theband depth at 062 μm in the new spectra of Pluto and in thespectra of Makemake and Eris permits us to estimate the Lambertcoefficient not measured yet at this wavelength at a temperatureof 30 K and 40 KWe find that all the CH bands present a blue shift This shift isminimum at the Charon-facing hemisphere where the CH is alsomore abundant indicating a higher degree of saturation of CH inthe CH N dilution at this hemisphereComparing with data in the literature we found that thelongitudinal and secular variations of the parameters measured inour spectra are in accordance with previous results and with thedistribution of the dark and bright material as showed by thePlutos albedo maps from New HorizonsIn 2015 new observations were run quasi-simultaneously with theNew Horizons flyby at 10 different Pluto longitudes (July 3 to 14) The data are currently being reduced

Author(s) Vania Lorenzi Noemiacute Pinilla-Alonso Joshua PEmery Javier Licandro Dale P Cruikshank Will Grundy Richard P BinzelInstitution(s) 1 Department of Earth amp Planetary SciencesUniversity of Tennesse 2 Fundacioacuten Galileo Galilei - INAF 3Instituto Astrofiacutesico de Canarias IAC 4 Lowell Observatory 5Massachusetts Institute of Technology 6 NASA Ames ResearchCenter

21009 ndash New rotationally resolved spectra of Pluto-Charon from 350 - 900 nmWe are using the 11-meter Southern African Large Telescope(SALT) to acquire high-resolution rotationally resolved visiblespectra of Pluto-Charon We use the Robert Stobie Spectrograph(RSS) to observe Pluto-Charon from 350 nm to 900 nm At 500nm resolution is 005 nm (R ~ 100000) and SNR per spectralresolution element is ~ 500We planned observations for 13 dates during June-September2014 and 13 more dates during June-September 2015 Theobservations for each season were spaced so as to equally sample

Plutos 65-day rotational period As of the abstract submission wehave data from 11 nights (2014) and 9 nights (2015) in hand Mostof the observations were taken with observations of solar-type starHD 146233 to determine the surface reflectivityOur results will provide constraint on the composition and spatialdistribution of material on Plutos surface enabling comparison toprevious epochs and near-infrared results and giving aground-truth for New Horizons July 2015 flyby In addition ourdata will allow us to search for new spectral features in the range350 nm to 600 nm at a sensitivity substantially higher thanpreviously published searches

Author(s) Henry B Throop Will Grundy Cathy B Olkin Leslie A Young Amanda A SickafooseInstitution(s) 1 Lowell Observatory 2 PSI 3 South AfricanAstronomical Observatory 4 Southwest Research Institute

21010 ndash Spectroscopy of Plutos Surface from 28 - 36microm during the New Horizons FlybySpectroscopy of Pluto in the 1 - 25 microm range has produced keyresults over the past two decades identification of nitrogen COmethane and ethane ices longitudinal variability in theconcentrations of these ices evidence of dissolved vs puremethane and nitrogen ices and the surface temperature andcrystalline state of nitrogen ice (eg Douteacute et al 1999 Holler etal 2014) Only a few spectra have been published at wavelengthsfrom 25 - 5 microm (eg Protopapa et al 2008 Olkin et al 2007)but these few L- and M-band spectra changed our interpretation ofPlutos surface the depth of the 33 microm methane band precludessignificant regions of pure of nitrogen ice the slope of the methaneband at 31-32 microm is sensitive to the fraction of pure methane vsmethane that is diluted in nitrogen frost and an absorption featureat 467 microm needs an identified source (but could be due to COCH3D or other constituent) The LEISA instrument on NewHorizons obtained spectra of Plutos surface at wavelengthsbetween 125 - 25 microm To complement the spacecraftinstrumentation we observed Plutos disk-integrated spectra from28 - 36 microm on two half-nights (12-JUL-2015 and 14-JUL-2015(UT)) using the NIRSPEC spectrograph at the WM KeckObservatory Conditions were excellent throughout most of theobserving run with seeing under 05 at K We will compare ourresults to observations obtained in 2001 with the same instrumentand report on evidence for surface constituents that have beenfound at shorter wavelengthsReferencesDouteacute et al Evidence for methane segregation at the surface ofPluto Icarus 142 421-444 (1999)Holler BJ et al Evidence for longitudinal variability of ethaneice on the surface of Pluto Icarus 243 104-110 (2014)

Author(s) Eliot F Young Leslie A Young Henry Roe Bryan J HollerInstitution(s) 1 Lowell Observatory 2 Southwest ResearchInst 3 University of Colorado

21011 ndash Glacial Flow on and onto Sputnik PlanumSputnik Planum (SP) is the high albedo apparently crater-freewestern portion of Tombaugh Regio imaged in July by the NewHorizons LORRI instrument The relatively high resolution (400mpix) LORRI mosaics of the northern portions of the planumbordered by the Cousteau Rupes (CR) scarp reveal surface patternshighly suggestive of viscous flow dynamics Spectroscopicmeasurements of SP taken by the New Horizons LEISA instrumentalso indicate that SP is a region containing a significant amount ofCO It has also been long known that CO and N are associatedwith one another on SP Taken together these observationssuggest the possibility that the high albedo material on SP is avolatile ice mix possibly flowing atop a bedrock-like substrate Theapparent notable lack of craters on SP strongly suggests that theflow processes act on relatively fast geologic timescales Using theknown properties of various volatile ice mixtures in thetemperature range of interest we formulate and implement anumerical landform evolution model in order to examine a numberof hypothetical evolutionary scenarios for SP and its environs This

2 1 3

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[12]

[2] 2[3-4]

39

work was supported by NASAs New Horizons project All place names on Pluto and Charon are informally known as

such as of the writing of this abstract Stern S A et al 2015Science Grundy amp Buie 2001 Icarus 153 248 Grundy et al2013 Icarus 223 710

Author(s) O M Umurhan J M Moore W B McKinnon A D Howard F Nimmo W Grundy S A Stern H Weaver C Olkin K Ennico L A YoungInstitution(s) 1 Johns Hopkins University Applied PhysicsLaboratory 2 Lowell Observatory 3 NASA-Ames ResearchCenter 4 Southwest Research Institute 5 University ofCalifornia Santa Cruz 6 University of Virginia 7 WashingtonUniversity St Louis

21012 ndash A Central Flash at an Occultation of a BrightStar by Pluto Soon Before New Horizons FlybyFrom the Mt John Observatory New Zealand we were so close tothe center of the occultation path on 29 June 2015 UTC that weobserved a modest central flash from the focusing of starlight froma 12th-magnitude star The star was one of the brightest ever in ouryears of continual monitoring that started in 2002 At the time ofPlutos perihelion in 1989 it was feared from models that Plutosatmosphere might collapse by now a motivation for the timelylaunch of New Horizons some models now allow Pluto to retain itsatmosphere throughout its orbitWe used our frame-transfer CCD at 10 Hz with GPS timing on the1-m McLellan telescope of Canterbury U We also observed with aLowell Obs infrared camera on the AAVSO 06-m OpticalCraftsman telescope and obtained 3-color photometry at a slowercadence on a second 06-m telescope We coordinated with theoverflight of SOFIA and its 25-m telescope which benefited fromlast-minute astrometry and the Auckland Observatorys and otherground-based telescopesOur light curves show a modest central flash our tentativegeometrical solution shows that we were only about 50 km fromthe occultation paths centerline The flash is from rays lower thanotherwise accessible in Plutos atmosphere Our light curves atsuch high cadence that we see spikes caused by atmospheric effectsthat we had not seen so well since our 2002 Mauna Kea occultationobservations show that Plutos atmosphere had not changeddrastically since our previous years observations Our data providea long-term context for New Horizons highly-detailed observationsof Plutos atmosphere in addition to providing a chord for thegeometrical solution that includes SOFIAs observationsOur observations were supported by NASA Planetary Astronomygrants NNX12AJ29G to Williams College NNX15AJ82G to LowellObservatory and NNX10AB27G to MIT and by the NationalResearch Foundation of South Africa We are grateful to AlanGilmore Pam Kilmartin Robert Lucas and Carolle Varughese forassistance at Mt John We thank the AAVSO for use of theAAVSOnet 06-m telescope and Arne Henden for assistance

Author(s) Jay M Pasachoff Bryce A Babcock Rebecca FDurst Christina H Seeger Stephen E Levine Amanda SBosh Amanda A Sickafoose Michael J Person Fumio Abe Daisuke Suzuki Masayuki Nagakane Paul J TristamInstitution(s) 1 Lowell Obs 2 MIT 3 Mt John U Obs 4Nagoya U 5 Notre Dame 6 Osaka U 7 Williams College

21013 ndash Placing SOFIA in the central flash for the 29June 2015 Pluto OccultationWe report on the astrometry prediction process carried out for the29 June 2015 occultation of an 119 magnitude star by Pluto Theoccultation star UCAC2 139-209445 was first identified in 2013 asa good candidate for an occultation to be observed withStratospheric Observatory for Infrared Astronomy (SOFIA) due tothe circumstances of the event In addition the events proximity tothe New Horizons encounter with Pluto made the event even moretimely We were awarded time on SOFIA for the Pluto occultationin 2014 From mid-2014 up through the night of the occultationwe tracked Plutos position We collected astrometric data fromfour telescopes the SARA-CT telescope located in Cerro TololoInternational Observatory Chile the Lowell Observatory 42-inch

Hall telescope the Lowell Observatory 43-m Discover ChannelTelescope both in Flagstaff AZ and the USNO 155-m Kaj Strandtelescope in Flagstaff AZ The objective of the astrometricobservations was to improve the prediction enough to place theaircraft within the central flash zone (approximately plusmn75 km 5masfrom the center line of the Pluto shadow)The prediction uncertainties included those of the star position andproper motion Pluto ephemeris offset potential zone-dependentoffsets in the reference catalog unknown stellar duplicity andcenter-of-mass to center-of-light offsets Over the two years sincewe identified this event as promising we worked to steadilydecrease each of the sources of uncertaintyWe communicated prediction updates to the SOFIA flight planningteam We provided a pre-take-off update which was then followedby a later in-flight update that necessitated a change in the flightplan of 320 km The crew were able to implement this change andSOFIA was able to capture the central flash of this event (Bosh etal and Person et al this conference)

Author(s) Carlos A Zuluaga Amanda S Bosh Michael JPerson Stephen E Levine Len P Bright Hugh C Harris Trudy Tilleman Thanawuth Thanathibodee Luke WWeisenbachInstitution(s) 1 Lowell Observatory 2 Massachusetts Instituteof Technology 3 US Naval Observatory

21014 ndash Constraints on Plutos Hazes from 2-ColorOccultation LightcurvesThe controversial question of aerosols in Plutos atmosphere firstarose in 1988 when features in a Pluto occultation lightcurve werealternately attributed to haze opacity (Elliot et al 1989) or athermal inversion (Eshleman 1989) A stellar occultation by Plutoin 2002 was observed from several telescopes on Mauna Kea inwavelengths ranging from R- to K-bands (Elliot et al 2003) Thisevent provided compelling evidence for haze on Pluto since themid-event baseline levels were systematically higher at longerwavelengths (as expected if there were an opacity source thatscattered more effectively at shorter wavelengths) Howeversubsequent occultations in 2007 and 2011 showed no significantdifferences between visible and IR lightcurves (Young et al 2011)The question of haze on Pluto was definitively answered by directimaging of forward-scattering aerosols by the New Horizonsspacecraft on 14-JUL-2015 We report on results of a bright stellaroccultation which we observed on 29-JUN-2015 in B- and H-bandsfrom both grazing and central sites As in 2007 and 2011 we see noevidence for wavelength-dependent extinction We will present ananalysis of haze parameters (particle sizes number density profilesand fractal aggregations) constraining models of haze distributionto those consistent with and to those ruled out by the occultationlightcurves and the New Horizons imagingReferencesElliot JL et al Plutos Atmosphere Icarus 77 148-170 (1989)Eshleman VR Plutos Atmosphere Models based on refractioninversion and vapor pressure equilibrium Icarus 80 439-443(1989)Elliot JL et al The recent expansion of Plutos atmosphereNature 424 165-168 (2003)Young EF et al Search for Plutos aerosols simultaneous IRand visible stellar occultation observations EPSC-DPS JointMeeting 2011 held 2-7 October 2011 in Nantes France (2011)

Author(s) Kara Hartig T Barry C Y Carriazo A Cole D Gault B Giles D Giles K M Hill R R Howell GHudson B Loader J A Mackie C B Olkin P Rannou JRegester A Resnick T Rodgers B Sicardy M FSkrutskie A J Verbiscer L H Wasserman C R Watson E F Young L A Young M W Buie M NelsonInstitution(s) 1 Amherst College 2 Brown University 3Greensboro Day School 4 Kuriwa Observatory 5 LowellObservatory 6 Paris Observatory 7 Pomona College 8Princeton Instruments 9 Royal Astronomical Society of NewZealand 10 Southwest Research Inst 11 Universiteacute ReimsChampagne-Ardenne 12 University of Tasmania 13 Universityof Virginia 14 University of Wyoming 15 Western SydneyAmateur Astronomy Group

[1][2]

[3] [4]

3 3 76 5 2 4 1

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21015 ndash The State of Plutos Bulk Atmosphere at theTime of the New Horizons EncounterOn 29-JUL-2015 our team - plus many critical amateurastronomers - observed a stellar occultation by Pluto from sites inAustralia and New Zealand This event was remarkable for tworeasons it preceded the New Horizons flyby of Pluto by just twoweeks and the occulted star was about 10x brighter than Plutoitself by far the brightest Pluto occultation event observed to dateThe separation of ground sites spanned nearly 900 km with respectto the central chord allowing a good geometric solution for theshadow path The lightcurves show some inflection points andbroad fangs that are characteristic of perturbations in thetemperature profile Preliminary fits show that the temperatureprofile derived from a 2006 occultation (Young et al 2008)reproduces the 29-JUN-2015 lightcurves well Assuming a surfaceradius of 1187 km for Pluto we find that the surface pressure is 18+- 3 microbar This pressure indicates that Plutos surface has not yetstarted to cool down despite a decrease in absorbed solar flux ofmore than 17 since perihelion in 1988 A surface pressure of 18microbar would correspond to a nitrogen ice surface temperature of380 KReferencesYoung EF et al Vertical Structure in Plutos Atmosphere fromthe 2006 June 12 Stellar Occultation AJ 136 1757-1769 (2008)

Author(s) Aaron C Resnick T Barry MW Buie CYCarriazo A Cole D Gault B Giles D Giles K Hartig K Hill RR Howell G Hudson B Loader J Mackie MNelson C Olkin J Register T Rodgers B Sicardy MSkrutskie A Verbiscer L Wasserman C Watson EYoung L Young A ZaluchaInstitution(s) 1 Amherst College 2 Brown University 3Greensboro Day School 4 Kuriwa Observatory 5 LowellObersvatory 6 Paris Observatory 7 Pomona College 8Princeton Instruments 9 Royal Astronomical Society of NewZealand 10 SETI 11 SwRI 12 University Of Tasmania 13University of Virginia 14 University of Wyoming 15 WesternSydney Amateur Astronomy Group

21016 ndash Predictions for the escape of CH from PlutoObservations of Plutorsquos extended atmosphere by the NewHorizonsALICE instrument have the potential to constrainmodels of energy-limited escape from planetary atmospheres Suchmodels have wide applicability ranging from dwarf planets in thesolar system to giant extrasolar planets but the opportunities totest them in actual atmospheres are limited We adapted a multi-species escape model from close-in extrasolar planets to calculatethe escape rates of CH and N from Pluto In the absence ofescape CH should overtake N as the dominant species below theexobase Theory suggests however that Plutorsquos atmosphereundergoes rapid escape that leads to a nearly constant CH mixingratio of about 1 below the exobase with CH escaping at a ratethat is only 5-10 of the N escape rate Simultaneousobservations of the N and CH profiles in the upper atmospheretogether with our model can be used to test if this is the case andinfer an estimate of the mass loss rate

Author(s) Tommi Koskinen Justin T Erwin Roger V YelleInstitution(s) 1 Lunar and Planetary Laboratory

21017 ndash Radiative equilibrium and escape of PlutosatmosphereObservations of Plutorsquos extend atmosphere by the New Horizonsspacecraft motivate an update to our modeling effort on Plutorsquosatmosphere New Horizons observations have already improvedour constraints on planet radius and surface pressure which arekey to modeling the atmospheric structure We model the radiativeconductive equilibrium in the lower atmosphere combined with theUV driven escape model of the upper atmosphere The non-LTEradiative transfer model in the lower atmosphere include heatingand cooling by CH CO and HCN The escape model of the upperatmosphere is updated to include diffusion and escape of eachmolecular component These results will be used to aid in theanalysis and better understanding of the full atmospheric

structure

Author(s) Justin Erwin Tommi T Koskinen Roger V YelleInstitution(s) 1 Lunar and Planetary Lab UA

21018 ndash Plutos atmosphere in 2015 fromhigh-resolution spectroscopyPlutos thin N2CH4 atmosphere is in vapor-pressure equilibriumwith ices on its surface The atmosphere evolves seasonally withthe varying insolation pattern on Plutos heterogenous surfaceperhaps even largely freezing out to the surface during the coldestportion of Plutos year We use high-resolution(Rasymp25000-50000) near-infrared spectroscopy to resolveatmospheric methane absorption lines from Plutos continuumspectra as well as separate Plutos atmospheric lines from thetelluric spectrum In addition to measuring the abundance andtemperature of Plutos atmospheric CH4 with broad wavelengthcoverage we are able to search for the inevitable products ofN2CH4 photochemistry In 2015 we are undertaking an intensivecampaign using NIRSPEC at Keck Observatory and IGRINS(Immersion Grating INfrared Spectrometer) at McDonaldObservatory to coincide with the New Horizons Pluto encounterWe will report initial results from this 2015 campaign and comparethe state of Plutos atmosphere at the time of the New Horizonsencounter with earlier years

Author(s) Henry G Roe Jason C Cook Gregory N Mace Bryan J Holler Leslie A Young Jacob N McLane Daniel TJaffeInstitution(s) 1 Lowell Obs 2 SwRI 3 University ofColorado Boulder 4 University of Texas at Austin

21019 ndash 12 years of Pluto surfaces evolutioninvestigated with radiative transfer modelingThe evolution of Plutorsquos surface through time due to surface -atmosphere interactions remains unknown New Horizons willprovide very high spatial resolution data of its surface state but onlyas a snapshot Furthermore this evolution during the last decadesis supposed to be fast due to the recent passage of Pluto through itsperihelion (1989) Ground based survey data over a long period oftime are thus crucial to understand the long-term evolution of thedwarf planet surfaceIRTFSpeX reflectance spectra of Pluto have been acquired during13 years (2001-2013) between 08-24 μm (Grundy et al 2013Grundy et al 2014) This set of data present the opportunity tomonitor possible changes of the surface in terms of geographicaldistribution and segregation between different chemical speciesthat are known to be present at the surface in an icy state (N CHand CO Owen et al 1993 Douteacute et al 1999) These variations arerecorded through changes in the infrared absorption bands of thedifferent ices A study based on band criteria variation (Grundy etal 2013) showed that CH absorption bands are increasingthrough time whereas N and CO absorptions bands aredecreasing (Grundy et al 2014) However quantitativeinterpretation of these data needs further investigation anddetailed radiative transfer modelingWe used the bidirectional reflectance model of Douteacute amp Schmitt(1998) to fit the IRTFSpeX spectral data This model takes intoaccount a possible stratification of chemical species aphenomenon that is likely to occur on Pluto where CH issupposed to accumulate on a sublimating molecular mixture ofN -CH -CO (Douteacute et al 1999) Different modelings take intoaccount pure CH ice a molecular mixture of N -CH -CO tholinsand water ice We modeled the grand average spectra and thenallowed the parameters to vary around the average values to modelindividual spectra and get quantitative variations of the differentspeciesPreliminary results of these modelings will be presented in terms oflongitudinal and temporal variations This study could provide auseful precursor for the analysis of the spatially resolved NewHorizon hyper spectral data acquired by the RALPHLeisainstrument

1 15 111 12 4 12 15 2

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Author(s) Sylvain Philippe Bernard Schmitt WilliamGrundy Silvia Protopapa Cathy OlkinInstitution(s) 1 Institut de Planeacutetologie et dAstrophysique deGrenoble 2 Lowell Observatory 3 Southwest Research Institute 4 University of Maryland

21020 ndash Modeling the seasonal evolution of thesurface distribution of N2 CH4 and CO ices on Plutoto interpret New Horizons observationsThe distribution of nitrogen methane and carbon monoxide iceson Pluto as observed by New Horizons is controlled by the intenseseasonal cycle and possibly by some internal sources To betterunderstand the seasonal processes we have developed a detailedmodel of the ices cycles derived from a full Global Climate Model(GCM see Forget et al this issue) but in which the transport bythe atmosphere is parametrized based on reference GCMsimulations This allows to simulate the seasonal ices cycles onPluto for thousands of yearsThe resulting distribution primarily depends on the seasonalthermal inertia used for the different ices and is affected by theassumed topography as well As observed it is possible to formpermanent deposits in the equatorial regions with possiblelongitudinal variations depending on the topography In particularwe will discuss how the elevation of the anti-Charon point which isnot random since its location is the output of the Pluto-Charontidal locking process may explain the formation of the TombaughRegio ice deposits

Author(s) Tanguy Bertrand Franccedilois ForgetInstitution(s) 1 Laboratoire de Meacuteteacuteorologie Dynamique UPMC

21021 ndash Pluto Photochemical Models for the NewHorizons FlybyWe have designed a state-of-the-art 1-D chemistry-transport modelfor Plutorsquos atmosphere as a prelude to New Horizonsrsquo flyby on July14 2015 and as a tool with which to analyze and understand thedata gathered by the New Horizons spacecraft Prior to the closeencounter many atmospheric properties remain unknown Ourmodel demonstrates the sensitivity of hydrocarbon and HCNprofiles to the eddy mixing strength in the lower atmosphereWhen the New Horizons data arrive this model stands primed toaid the characterization of Plutorsquos atmospheric chemistry anddynamics If atmsopheric measurements have beenobtainedreleased by the time of this presentation we will show acomparison between our model and the data

Author(s) Michael L Wong Randy Gladstone Michael ESummers Yuk L YungInstitution(s) 1 California Institute of Technology 2 GeorgeMason University 3 Southwest Research Institute

21022 ndash Pluto Modeling of 3-D Atmosphere-SurfaceInteractionsAtmosphere-surface interactions on Pluto are of great importanceto creating and maintaining the atmospheric variations andheterogeneous surface that have been observed by New Horizonsand two decades prior work Publicly released imagesdata fromNew Horizons contain numerous fascinating surface features andconstrasts Insights into their origin maintenance andorevolution may be gleaned through multidisciplinary climatemodeling Some results from such modeling will be presented withan emphasis on shorter-timescale interactions

Author(s) Timothy I MichaelsInstitution(s) 1 SETI Institute

21023 ndash Mass loss from the atmosphere of PlutoMolecules can escape readily from the atmosphere of PlutoHydrodynamic escape is a process that drives large scale escapeThe process was generally believed to produce rather small isotopicfractionation Here we show that the escape highly fractionates theisotopic composition of nitrogen The process preferentially selectslighter species with an escape probability ~30 higher for the

lighter isotopologue This fractionation factor is higher than thefractionations occurring in most of known processes in modifyingthe distributions of molecules in the planetary atmospheres Thevalidity of the model can be tested against the upcoming datamainly nitrogen abundance in the outer atmosphere of Pluto fromthe New Horizons The property of the selection can significantlymodify the isotopic composition of the atmosphere leaving thepresent-day atmosphere isotopically heavier than the ancient oneThis also impacts the current view of the evolution of planetaryatmospheres Venus for example may not need that much massloss in order to explain the current DH ratio

Author(s) Mao-Chang Liang Chien-Chang Yen RonaldTaamInstitution(s) 1 Academia Sinica

21024 ndash Long-term Simulations of PlutosAtmosphere and Surface as a Coupled SystemPrevious work has modeled either Plutos atmosphere orsurfacesubsurface as separate entities In reality these tworegions should be coupled energetically and physically because ofthe accumulation sublimation and transport of volatiles (hereN2) Simulation results over multi-Pluto years are presented froma general circulation model that has both detailed atmospheric andsurfacesubsurface modules As the initial model conditions thatwill ultimately reproduce the observed surface pressures from NewHorizons stellar occultation data and spectroscopic observationsare not known by trial and error the model is initialized withdifferent surface pressures and amounts of surface ice (collectivelyknown as the volatile inventory) This ldquobrute forcerdquo method is nowa viable strategy given the ongoing development of the Plutogeneral circulation model (based on the MIT general circulationmodel dynamical core Zalucha amp Michaels 2013) and modernsupercomputing power The coupled atmosphere andsurfacesubsurface model is run until a yearly repeatable frost cycleoccurs (if at all) Surface coverage of volatiles and surface pressurewill be presented from the various scenarios Ancillary variablessuch temperature (of both the atmosphere andsurfacesubsurface) and wind direction and magnitude will also beshown for cases of particular interest

Author(s) Angela M ZaluchaInstitution(s) 1 SETI Institute

21025 ndash Extended Neutral Cloud around Plutorsquos OrbitRecent studies estimate the approximate escape rate of molecularnitrogen from Pluto as well as its ionization rate In this study wefocus on the implications of this escaping nitrogen and theresulting extended neutral cloud around Plutorsquos orbit by simulatingthe escaping nitrogen with a numerical model Several unknownparameters are varied including the dependence of Plutorsquosproduction rate on orbital distance and the distribution of speeds atwhich nitrogen is escaping Pluto

Author(s) Evan Sidrow F BagenalInstitution(s) 1 University of Colorado - Boulder

21026 ndash Pluto Near and Far PEPSSI Measurementsof Energetic Particles During the New Horizons Flybyand Investigating a Pluto Torus of CircumsolarNeutral GasThe energetic particle environment at Pluto has been unknownand little modeled until this yearrsquos historic encounter by the NewHorizon (NH) spacecraft on 14 July 2015 The first energeticparticle observations made with the Pluto Energetic ParticleSpectrometer Science Investigation (PEPSSI) instrument weredownlinked in August 2015 There are variations in the intensitiesof suprathermal (~3-30 keVnucleon) ions that are associated witha combination of the position of the spacecraft relative to Pluto thelook direction of PEPSSI and (potentially) temporal evolution inthe system We present the results of the near encounter withPluto to as close as ~116 R (1 R = 1187 km) which earlyanalysis shows include large intensity variations associated withPluto We also present the concept of a neutral gas torus

1 12 4 3

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42

surrounding the Sun aligned with Plutorsquos orbit and placeobservational constraints on it based primarily on comparison ofNH measurements with a 3-D Monte Carlo model adapted fromanalogous satellite tori surrounding Saturn and Jupiter Such atorus or perhaps partial torus could result from neutral Nescaping from Plutorsquos exosphere Unlike other more massiveplanets gaseous neutrals escape Pluto readily via Jeans escape(ie owing to the high thermal speed relative to the escapevelocity) These neutrals are not directly observable by NH butonce ionized to N or N via photolysis or charge exchange arepicked up by the solar wind ultimately reaching ~50 keV or moremaking these pickup ions detectable by PEPSSI This work wassupported by NASAs New Horizons project

Author(s) Matthew Eric Hill Peter Kollmann Ralph LMcNutt H Todd Smith Fran Bagenal Lawrence E Brown Heather A Elliott Dennis K Haggerty Mihaly Horanyi Stamatios M Krimigis Martha Kusterer Carey M Lisse David JMcComas Marcus Piquette Darrell Strobel Jamey Szalay Jon Vandegriff Eric Zirnstein Kimberly Ennico Cathy BOlkin Harold A Weaver Leslie A Young S A SternInstitution(s) 1 Johns Hopkins University 2 Johns HopkinsUniversity Applied Physics Laboratory 3 NASA Ames ResearchCenter 4 Southwest Research Institute 5 Southwest ResearchInstitute 6 University of Colorado

21027 ndash Crystalline and amorphous H O on CharonCharon the largest satellite of Pluto is a gray-colored icy worldcovered mostly in H O ice with spectral evidence for NH aspreviously reported (Cook et al 2007 Astrophys J 6631406ndash1419 Merlin et al 2010 Icarus 210 930 Cook et al 2014AASDivision for Planetary Sciences Meeting Abstracts 4640104) Images from the New Horizons spacecraft reveal asurface with terrains of widely different ages and a moderate degreeof localized coloration The presence of H O ice in its crystallineform (Brown amp Calvin 2000 Science 287 107-109 Buie amp Grundy2000 Icarus 148 324-339 Merlin et al 2010) along with NH isconsistent with a fresh surfaceThe phase of H O ice is a key tracer of variations in temperatureand physical conditions on the surface of outer Solar Systemobjects At Charonrsquos surface temperature H O is expected to beamorphous but ground-based observations (eg Merlin et al2010) show a clearly crystalline signature From laboratoryexperiments it is known that amorphous H O ice becomescrystalline at temperatures of ~130 K Other mechanisms that canchange the phase of the ice from amorphous to crystalline includemicro-meteoritic bombardment (Porter et al 2010 Icarus 208492) or resurfacing processes such as cryovolcanismNew Horizons observed Charon with the LEISA imagingspectrometer part of the Ralph instrument (Reuter DC SternSA Scherrer J et al 2008 Space Science Reviews 140 129)Making use of high spatial resolution (better than 10 kmpx) andspectral resolving power of 240 in the wavelength range 125-25microm and 560 in the range 21-225 microm we report on an analysis ofthe phase of H O ice on parts of Charonrsquos surface with a view toinvestigate the recent history and evolution of this small butintriguing objectThis work was supported by NASArsquos New Horizons project

Author(s) Cristina M Dalle Ore Dale P Cruikshank WillM Grundy Kimberly Ennico Catherine B Olkin S AlanStern Leslie A Young Harold A WeaverInstitution(s) 1 Johns Hopkins University Applied PhysicsLaboratory 2 Lowell Observatory 3 NASA Ames Reseach Center4 SETI Institute 5 Southwest Research Institute

21028 ndash Charon QuandariesRecent data from New Horizons have revealed Charon as adynamic world with an apparently young surface experiencinggeological processes Tectonic features include a chasm seen onCharonrsquos terminator and cliffs or troughs that belt the moon Thelsquomountain-in-a-moatrsquo seen in LORRI images appears emplaced in adepression also suggesting an active process These raise thequestions How hot is Charonrsquos interior Are temperatures

sufficient for liquid (ie gt 176 K the water-ammonia eutectic)How close to the surface are these temperatures reached Howthick is Charonrsquos crust We will report our calculations of thesequantitiesFollowing [12] we hypothesize that Charon formed from acircumplutonian disk after a giant impact Unlike in the lsquointactmoonrsquo scenario a Charon accreted from a disk is everywhere gt 100K and its outermost surface is gt 250 K possibly leading to fulldifferentiation into rocky core and ice mantle [2] We suggest thatcontraction of Charon due to its cooling from this hot initial state toits present-day surface temperature asymp 50 K might lead to tectonicfeatures like those seen on Mercury [3] We calculate the thermalhistory of Charon using our published codes [45] We findtemperatures today at the base of the ice mantle are cold (lt 100 K)but that ice at sufficient depth in the core should melt producingliquid It is unclear whether this liquid could reach the surface fromthe core but it may do so via processes described by [6] This wouldhave implications for cryovolcanism resurfacing and thelsquomountain-in-a-moatrsquo We will discuss the results of our modelingand our interpretation of New Horizons data at the meetingReferences [1] Canup R (2005) Science 207 546-550 [2]Desch SJ (2015) Icarus 246 37-47 [3] Byrne P Klimczak C CelalSengor AM Solomon SC Watters TR amp Hauck SA (2014) NatureGeosci 7 301-307[4] Desch SJ Cook JC Doggett TC amp PorterSB (2009) Icarus 202 694-714 [5] Neveu M Desch SJ ampCastillo-Rogez JC (2015) J Geophys Res E 120 123-154 [6]Neveu M Desch SJ Shock EL amp Glein CR (2015) Icarus 24648-64

Author(s) Steven Desch Marc NeveuInstitution(s) 1 Arizona State Univ

21029 ndash Determination of the System Mass and theIndividual Masses of the Pluto System from NewHorizons Radio TrackingOne objective of the New Horizons Radio Science Experiment REXis the determination of the system mass and the individual massesof Pluto and Charon About four weeks of two-way radio trackingcentered around the closest approach of New Horizons to the Plutosystem were processed Major problems during the processing werecaused by the small net forces of the spacecraft thruster activitywhich produce extra Δv on the spacecraft motion superposed ontothe continuously perturbed motion caused by the attracting forcesof the Pluto system The times of spacecraft thruster activity areknown but the applied Δv needs to be specifically adjusted Notwo-way tracking was available for the day of the flyby but slots ofREX one-way uplink tracking are used to cover the most importanttimes near closest approach eg during occultation entries andexits This will help to separate the individual masses of Pluto andCharon from the system mass

Author(s) Matthias Hahn Martin Paumltzold Tom Andert Michael K Bird Leonard G Tyler Ivan Linscott Dave PHinson Alan Stern Hal Weaver Cathrin Olkin LeslieYoung Kimberly EnnicoInstitution(s) 1 Department of Electrical Engineering StanfordUniversity 2 Institut fuumlr Satellitentechnik und WeltraumnutzungUniversitaumlt der Bundeswehr Muumlnchen 3 Applied PhysicsLaboratory Johns Hopkins University 4 NASA Ames ResearchCenter 5 Rheinisches Institut fuumlr Umweltforschung an derUniversitaumlt zu Koumlln Abt Planetenforschung 6 SouthwestResearch Institute

21030 ndash The Infrared Spectra and AbsorptionIntensities of Amorphous Ices Methane and CarbonDioxideOur research group is carrying out new IR measurements of icysolids relevant to the outer solar system and the interstellarmedium with an emphasis on amorphous and crystalline icesbelow ~70 K Our goal is to add to the relatively meager literatureon this subject and to provide electronic versions of state-of-the-artdata since the abundances of such molecules cannot be deducedwithout accurate reference spectra and IR band strengths In thepast year we have focused on two of the simplest and most

2

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2

2 3

2

3

2

2

2

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5 5 1

1 1

5 5 25 1 1

1 6 3 66 4

43

abundant components of icy bodies in the solar system - methane(CH ) and carbon dioxide (CO ) Infrared spectra from sim 4500 to500 cm have been measured for each of these molecules inμm-thick films at temperatures from 10 to 70 K All knownamorphous and crystalline phases have been reproduced and forsome presented for the first time We also report measurements ofthe index of refraction at 670 nm and the mass densities for eachice phase Comparisons are made to earlier work where possibleElectronic versions of our new results are available athttpsciencegsfcnasagov691cosmicice constantshtml

Author(s) Perry A Gerakines Reggie L Hudson Mark JLoefflerInstitution(s) 1 NASA GSFC

21031 ndash Revisiting the 1988 Pluto OccultationIn 1988 Plutos atmosphere was surmised to exist because of thesurface ices that had been detected through spectroscopy but ithad not yet been directly detected in a definitive manner The keyto making such a detection was the stellar occultation methodused so successfully for the discovery of the Uranian rings in 1977(Elliot et al 1989 Millis et al 1993) and before that for studies ofthe atmospheres of other planetsOn 9 June 1988 Pluto occulted a star with its shadow falling overthe South Pacific Ocean region One team of observers recordedthis event from the Kuiper Airborne Observatory while otherteams captured the event from various locations in Australia andNew Zealand Preceding this event extensive astrometricobservations of Pluto and the star were collected in order to refinethe predictionWe will recount the investigations that led up to this importantPluto occultation discuss the unexpected atmospheric results andcompare the 1988 event to the recent 2015 event whose shadowfollowed a similar track through New Zealand and Australia

Author(s) Amanda S Bosh Edward W Dunham Leslie AYoung Steve Slivan Linda L Barba neacutee Cordella Robert LMillis Lawrence H Wasserman Ralph NyeInstitution(s) 1 Lowell Observatory 2 MIT 3 SouthwestResearch Institute 4 Wellesley College

21032 ndash Voyager IRIS Measurements of TritonsThermal Emission Impllications for PlutoThe New Horizons Pluto encounter data set includes uniqueobservations obtained using the Radio Science experiment tomeasure the night-side thermal emission at centimeterwavelengths well beyond the emission peak (in the 70 to 100micron range) 26 years ago the Voyager 2 Infrared InterferometerSpectrometer (IRIS) obtained spectra in the 30 - 50 micronwavelength range to try and detect thermal emission from Plutossibling Triton Conrath etal (1989) analyzed 16 of the IRIS spectraof Tritons dayside and derived a weak limit of 36 K - 41 K We haveanalysed those and an additional 75 spectra to refine the limits onthe temperature of Tritons surface and to explore diurnaldifferences in the thermal emission Triton results from otherVoyager instruments provide important constraints on ourinterpretation of the IRIS data as do Spitzer measurements ofPlutos thermal emissionFor unit-emissivity average temperature is 34 K inconsistent withthe pressure of Tritons atmosphere (13 - 19 microbar) thepresence of beta-phase nitrogen ice on the surface and the likelypresence ofwarm regions on the surface The atmospheric pressurerequires nitrogen ice temperatures of 374 K - 381 K which in turnrequires emissivity of 031--053 Such a low emissivity in thisspectral region might be expected if the surface is dominated bynitrogen or methane ice Averages of data subsets show evidencefor brightness temperature variations across Tritons surfaceSurprisingly the data seem to indicate that Tritons nightsideequatorial region was warmer than on the daysideThese Voyager results for Triton provide a useful context forinterpreting New Horizons and ALMA observations of emissionfrom Pluto in the sub-millimeter and centimeter region JWST willbe capable of detecting Tritons and Plutos 10 - 28 micron thermalemission although scattered light from Neptune may be an issue

for the Triton Combined with new capabilities of ALMA tomeasure the sub-millimeter emission (and even resolve the disksof Pluto and Triton) it seems possible that we may gain significantnew insights into the thermal properties of these bodies in thecoming decade

Author(s) John A Stansberry John Spencer IvanLinscottInstitution(s) 1 Southwest Research Institute 2 SpaceTelescope Science Institute 3 Stanford University

21033 ndash Exploring potential Pluto-generated neutraltoriThe NASA New Horizons mission to Pluto is providingunprecedented insight into this mysterious outer solar systembody Escaping molecular nitrogen is of particular interest andpossibly analogous to similar features observed at moons of Saturnand Jupiter Such escaping N has the potential of creatingmolecular nitrogen and N (as a result of molecular dissociation)tori or partial toroidal extended particle distributions The presenceof these features would present the first confirmation of anextended toroidal neutral feature on a planetary scale in our solarsystem While escape velocities are anticipated to be lower thanthose at Enceladus Io or even Europa particle lifetimes are muchlonger in Plutorsquos orbit because as a result of much weaker solarinteraction processes along Plutorsquos orbit (on the order of tens ofyears) Thus with a ~248 year orbit Pluto may in fact begenerating an extended toroidal feature along it orbitFor this work we modify and apply our 3-D Monte Carlo neutraltorus model (previously used at Saturn Jupiter and Mercury) tostudyanalyze the theoretical possibility and scope of potentialPluto-generated neutral tori Our model injects weighted particlesand tracks their trajectories under the influence of all gravitationalfields with interactions with other particles solar photons andPluto collisions We present anticipated N and N tori based oncurrent estimates of source characterization and environmentalconditions We also present an analysis of sensitivity to assumedinitial conditions Such results can provide insight into the Plutosystem as well as valuable interpretation of New Horizonrsquosobservational data

Author(s) Howard T Smith Matthew Hill PeterKollMann Ralph McHuttInstitution(s) 1 Johns Hopkins Applied Physics Lab

21034 ndash Visible-band (390-940nm) monitoring of thePluto absorption spectrum during the New HorizonsencounterWhilst Earth-based observations obviously cannot compete withNew Horizonsrsquo on-board instrumentation in most regards the NewHorizons data set is essentially a snapshot of Pluto in July 2015The New Horizons project team therefore coordinated a broadinternational observing campaign to provide temporal context andto take advantage of the once-in-a-lifetime opportunity to directlylink our Earth-based view of Pluto with ldquoground truthrdquo provided byin situ measurements This both adds value to existing archivaldata sets and forms the basis of long term monitoring as we watchPluto recede from the Sun over the coming years We presentvisible-band (390-940nm) monitoring of the Pluto absorptionspectrum over the period July - October 2015 from the LiverpoolTelescope (LT) In particular we wished to understand thewell-known 6-day fluctuation in the methane ice absorptionspectrum which is observable from Earth in relation to the never-before-available high resolution maps of the Pluto surface The LTis a fully robotic 20m optical telescope that automatically anddynamically schedules observations across 30+ observingprogrammes with a broad instrument suite It is ideal for bothreactive response to dynamic events (such as the fly-by) and longterm stable monitoring with timing constraints individuallyoptimised to the science requirements of each programme Forexample past studies of the observed CH4 absorption variabilityhave yielded ambiguity of whether they were caused by realphysical changes or geometric observation constraints in large partbecause of the uneven time sampling imposed by traditional

4 2‑1

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44

telescope scheduling

Author(s) Robert J Smith Jonathan M MarchantInstitution(s) 1 Astrophysics Research Institute Liverpool JohnMoores University

21035 ndash Photos from Inside Pluto Historic Imagesfrom the New Horizons Encounter with PlutoNASAs New Horizons mission flew past Pluto on July 14 2015 Inthe months and weeks leading up to the encounter over 200mission personnel were located at JHU APL and directly involvedin the planning and operations of the flyby Several members of theteam were given special permission to document photographicallythis historic event These photos have been collected into a publicarchive which allows the general public to see the intimate andnormally hidden behind the scenes views of an operatingspacecraft team through times of elation times of stress publiccelebrations and private momentsWe present here a variety of these photos spanning May (thebeginning of detailed hazards searches) through the end of JulyThe entire archive will be available online and accessible to thepublicWe thank JHU-APL for arranging special permission for thephotographers (HBT CSS JS SJR DC) All photos are usedcourtesy NASASwRIJHUAPL and the individual photographers

Author(s) Henry B Throop John Spencer Stuart JRobbins Constantine Tsang Dale Cruikshank S Alan Stern Harold Weaver Peter Bedini Andrew CallowayInstitution(s) 1 JHU-APL 2 NASA Ames 3 PSI 4 SwRI

211 ndash Centaurs Trans-Neptunian Objectsand the Inner Oort Cloud21101 ndash Search for Binary TrojansWe have reexamined 41 Trojan asteroids observed with the HubbleSpace Telescope (HST) to search for unresolved binaries We haveidentified one candidate binary with a separation of 53 milliarcsecabout the width of the diffraction limited point-spread function(PSF) Sub-resolution-element detection of binaries is possiblewith HST because of the high signal-to-noise ratio of theobservations and the stability of the PSF Identification andconfirmation of binary Trojans is important because a Trojan Touris one of five possible New Frontiers missions A binary couldconstitute a potentially high value target because of theopportunity to study two objects and to test models of theprimordial nature of binaries The potential to derive mass-basedphysical information from the binary orbit could yield more cluesto the origin of Trojans

Author(s) Keith S Noll W M Grundy E L Ryan S DBenecchiInstitution(s) 1 Lowell Obs 2 NASA GSFC 3 PSI 4 U MD

21102 ndash A long term study of Centaur 174PEcheclusCentaur 174PEcheclus was discovered by the Spacewatch programon March 3 2000 and initially labelled (60558) 2000 EC 98 OnDecember 30 2005 a surprising cometary outburst was discoveredwith the 5-m Mount Palomar Observatory telescope This outburstcorresponded to a change in the overall visual magnitude fromabout 21 to about 14 At that time (60558) 2000 EC 98 was locatedat 1307 au to the Sun and was subsequently renamed with acometary designation This outburst lasted a few months and oneyear later no coma could be detected Another secondary outbursthappened in 2011 and lasted also a few months This target was atits perihelion (582 au) on April 22 2015We present new observational data obtained with the 25-m NordicOptical Telescope during the 2011 outburst and in July 2013 andwith the robotic 2-m Liverpool telescope on April 27 2014 August13 2014 and June 1 2015 We also found archive observationaldata obtained on December 22 2005These archive images point out the extremely high level of the174PEcheclus activity during the first outburst The R-magnitude

and Afrho parameter of the target were estimated to 148 and56000plusmn3000 cm respectively During the second outburst in 2011the activity level of the Centaur was lower the R-Afrho parameterswere 1200plusmn100 cm and 480plusmn70 cm in June and July respectivelyThe dust production rates needed to produce the observed comaewere approximately 700 kgs in 2005 and between 10 and 20kgs in 2011 assuming the average grain geometric albedo of 01and low outflow velocities of the dust less than 10 ms A possiblescenario of the dust coma formation for the first outburst will alsobe proposed using a Monte Carlo modelingBefore the outburst the lightcurve amplitude was 024 magnitudein the R-band with a rotation period of 2680 h (if a double-peakedlightcurve is assumed) The observational data obtained after theoutburst with the NOT do not permit to detect any clear variation inthe apparent magnitude at the level of about 01 magnitude Thedifferent possible explanations for this change will be discussed aswell as an analysis of the outbursts themselves

Author(s) Philippe Rousselot Pavlo Korsun Irina Kulyk Jean-Marc Petit Aureacutelie Guilbert-LepoutreInstitution(s) 1 Institut UTINAM 2 Main AstronomicalObservatory of NAS

21103 ndash Variability and Lightcurves Studies in theOuter Solar System Origins SurveyLightcurves provide a powerful mechanism for learning about thehistory of the collisional andor gravitational processes acting onsmall bodies since the formation and subsequent migration of oursolar nebula At the extremes they can provide constraints on thematerial properties (and interior structure) of individual objectsand perhaps in quantity can provide information about their sourcepopulations Our project consists of two datasets (1) the OuterSolar System Origins Survey (OSSOS) discovery and recoverymagnitudes and (2) observations from a 6-hour pilot study on asubset of (17) OSSOS objects using the Subaru and HyperSuprime-Cam (HSC) instrument The OSSOS objects span a fullrange of sizes from as large as several hundreds of km to as smallas a few tens of km in diameter Because of the telescope diameterand the wide field of view of HSC we are able to obtainmeasurements on multiple objects covering a range of magnitudeswith a single telescope pointing within the first two years followingobject discovery The OSSOS survey is well calibratedphotometrically and as such we use the very sparce sampling in thediscovery and recovery magnitudes to identify which objects mighthave the largest amplitude lightcruves indicating that they arelikely elongated or in potentially interesting spin states We thenselect the HSC fields containing these objects and the highestdensity of surrounding objects to obtain more densely sampledlightcurves In this way we optimize the telescope time and thepotential scientific return We will present our analysis of theOSSOS dataset and some preliminary results from HSC

Author(s) Susan D Benecchi Ying-Tung Chen MegSchwamb Shiang-Yu Wang Matthew Lehner MikeAlexandersenInstitution(s) 1 Institute of Astronomy amp Astrophysics atAcademia Sinica 2 Planetary Science Institute

21104 ndash Photometry of Scattered Disk Objects at 36μm and 45 μmScattered disk objects (SDO) are some of the most interesting of theestimated 100000 icy bodies located in the outer Solar SystemSDOs have been gravitationally disturbed and scattered by theorbital migration of Neptune The surface compositions of theseobjects provide a window into formation conditions and dynamicsof the outer Solar System Characterization of volatiles and organicmaterials in particular provide important constraints on formationconditions and subsequent surface processing of these objects Wemeasured fluxes of 36 SDOs at 36 μm and 45 μm using theInfrared Array Camera (IRAC) aboard the NASA Spitzer SpaceTelescope in order to characterize volatiles and organics on theirsurfaces Albedos calculated from these fluxes are combined withbroadband albedos from ground-based observations at shorterwavelengths (V R I J H K bands spanning 055 ndash 222 μm) to

1 1

3 44 4 2 4

1 1 1

2 1 43

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-1

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2 11 1 1

1

45

provide spectrophotometry from 05 to 45 μm Much of thoseground-based data are from previously published literatureHowever we have also conducted new ground-based Y J H Kobservations of several of the targets Sizes and visible geometricalbedos which are required to convert IRAC fluxes to geometricalbedos were extracted from published literature when availableand computed from absolute magnitudes otherwise The resultingspectrophotometry of these 36 SDOs shows a wide range of surfacecompositions Several of the SDOs we observed show red visibleand near-infrared spectral slopes and strong absorptions at 36 μmand 45 μm These absorption features suggest the presence ofcomplex organics Other SDOs appear red as well but show onlymoderate absorptions at 36 μm and 45 μm Moderate absorptionfeatures at these wavelengths may indicate a mixture of H O iceand refractory material on the surface Finally some objects showno absorption at 36 and 45 μm most likely characteristic ofsilicate dust We will discuss implications of these findings in termsof surface composition and possible origins

Author(s) Chad Mellton Joshua P Emery Noemi Pinilla-Alonso Michael Mommert Cassandra Lejoly David E TrillingInstitution(s) 1 Northern Arizona University 2 University ofTennessee Knoxville

21105 ndash A Chemical and Dynamical Link Between RedCentaur Objects and the Cold Classical Kuiper BeltWe present new B-V V-R and B-R colors for 32 Centaurs objectsusing the 43-meter Discovery Channel Telescope (DCT) nearHappy Jack AZ and the 18-meter Vatican Advanced TechnologyTelescope on Mt Graham AZ Combining these new colors withour previously reported colors we now have optical broad-bandcolors for 58 Centaur objectsApplication of the non-parametric Dip Test to our previous sampleof only 26 objects showed Centaurs split into gray and red groups atthe 995 confidence level and application of the Wilcoxon RankSum Test to the same sample showed that red Centaurs have ahigher median albedo than gray Centaurs at the 99 confidencelevel (Tegler et al 2008 Solar System Beyond Neptune U ArizonaPress pp 105-114)Here we report application of the Wilcoxon Rank Sum Test to oursample of 58 Centaurs We confirm red Centaurs have a highermedian albedo than gray Centaurs at the 997 level In additionwe find that red Centaurs have a lower median inclination anglethan gray Centaurs at the 995 confidence level Because of theirred colors and lower inclination angles we suggest red Centaursoriginate in the cold classical Kuiper belt We thank the NASA SolarSystem Observations Program for its support

Author(s) Stephen C Tegler William Romanishin GuyConsolmagnoInstitution(s) 1 Northern Arizona University 2 University ofOklahona 3 Vatican Observatory

21106 ndash Constraints to the Cold Classical KBOpopulation from HST observations of faint objectsThe size distribution of the known Kuiper Belt Objects has beendescribed by a double power law with a break at R magnitude 25There are two leading interpretations to this break 1) It is theresult of the collisional evolution among these KBOs with theobjects smaller than the break being the population most affectedby collisional erosion 2) The size distribution break is primordialset during the Kuiper Belt formationThe low inclination Kuiper Belt Objects the Cold Classicalpopulation is thought to have been dynamically isolated since theformation of the Solar System and thus only collisions betweenCold Classicals would have affected their size distribution If thesize distribution is collisional it probes parameters of the KuiperBelt history strengths of the bodies impact energies andfrequency and the the number of objects If the distribution isprimordial it reveals parameters of the Kuiper Belt accretion aswell as limits on its subsequent collisional historyIn this work we obtained new HST observations of 5 faint ColdClassicals which we combine with previous HST observations toexamine the distribution of two properties of the smallest KBOs

colors and binary fraction These two properties can differentiatebetween a primordial and a collisional origin of the size distributionbreak If the smaller bodies have been through extensive collisionalevolution they will have exposed materials from their interiorswhich has not been exposed to weathering and thus should bebluer than the old surfaces of the larger bodies An independentconstraint can be derived from the fraction of binary objects theangular momentum of the observed binaries is typically too high toresult from collisions thus a collisionally-evolved populationwould have a lower binary fraction due to the easier separation ofbinaries compared to the disruption of similar-sized bodies andthe easier disruption of the binary components due to the smallersizeWe will present the constraints to the color and binary fractiondistributions we are measuring from these observations whichprobe the smallest KBOs currently observable

Author(s) Paulo F Penteado David Trilling WilliamGrundyInstitution(s) 1 Lowell Observatory 2 Northern ArizonaUniversity

21107 ndash Quantifying the Infrared Spectra of IcyMethanol - A New Investigation for Solar SystemObjectsThe presence and abundances of organic molecules inextraterrestrial settings such as on TNOs can be determined usinginfrared (IR) spectroscopy but significant challenges existAlthough reference IR spectra for organics under relevantconditions are vital for such work for many molecules the dataneeded either do not exist or exist only in fragmentary form In thispresentation we describe new laboratory results for a three-element molecule methanol (CH OH) which has been reported tobe present in planetary and interstellar ices Near- and mid-IRspectra at various ice thicknesses and temperatures are presentedband strengths are calculated and optical constants are derivedResults are compared to those of earlier workers the influence ofassumptions found in the literature is explored and possiblerevisions to the literature are described Although IR spectra ofsolid CH OH has been reported by many low-temperaturelaboratory-astrochemistry groups over the past 25 - 30 years ourwork appears to be the first that aims to determine the densitiesrefractive indices and resulting mid-IR band strengths and opticalconstants of both the amorphous and crystalline phases ofmethanol The majority of the laboratory work in this project wasdone by Tatiana Tway who was supported by a summer internshipthrough the DREAM2 program which in turn is supported by agrant from NASArsquos SSERVI program

Author(s) Reggie L Hudson Tatiana Tway PerryGerakinesInstitution(s) 1 Delaware Valley University 2 NASA GoddardSpace Flight Center

21108 ndash Trans-Neptunian Objects Transiently Stuckin Neptunes Mean Motion Resonances numericalsimulations of the current populationInferring from observational data it is well known that a largepopulation of objects orbits the Sun in mean motion resonancewith Neptune with semi-major axes in the range a=30-100AUMany of these objects were likely caught into resonances byplanetary migration---either smooth or stochastic---approximately4 billion years ago Some however scattered off Neptune andbecome transiently stuck in more recent events The goal of thisproject is to form a testable model of the transient stickingpopulation through numerical simulation We calculate the relativelikelihood of resonance sticking from the current scattering diskinto a range of resonances We confirm that transiently stuckobjects are most prevalent in n1 resonances followed by n2 n3and so on The integrated time that objects spend stuck inresonance increases for resonances with longer orbital periods Wecalculate the expected distribution of libration amplitudes forresonance angles of stuck objects and comment on implications forthe origins of distant resonance populations

2

2 22 1 1 1

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3

3

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46

Author(s) Tze Yeung Mathew Yu Ruth Murray-Clay Kathryn VolkInstitution(s) 1 The University of Arizona 2 University ofCalifornia Santa Barbara

21109 ndash Dynamical Constraints on the Existence of a9th Planet Residing in the Inner Oort CloudThe discovery of Sedna a decade ago on a highly eccentric orbitbeyond the Kuiper belt challenged our understanding of the SolarSystem With a perihelion of 76 AU Sedna is well beyond the reachof the gas-giants and could not be scattered onto its highlyeccentric orbit from interactions with Neptune alone Sednarsquosaphelion at ~1000 AU is too far from the edge of the Solar Systemto feel the perturbing effects of passing stars or galactic tides in thepresent-day solar neighborhood Some other mechanism likely nolonger active in the Solar System today is required to emplaceSedna on its orbit Sednas presence predicts a population of icybodies on similar orbits residing past the Kuiper belt in what hasbeen called the Inner Oort CloudThe recent discovery of 2012 VP113 on a similar orbit to Sednaconfirmed the presence of the Inner Oort Cloud and identified apossible alignment of the argument of perihelion for objects withorbits detached from Neptune Based on the expected precessionfrequency the arguments of perihelion should be randomlydistributed The existence of a planet beyond 200 AU has beensuggested as a possible mechanism to actively control and lock theargument of perihelion of these orbits We use new dynamicalmodeling to further investigate this hypothesis and explore thepossible orbital configurations and physical properties of such abody residing beyond Neptune We will also discuss theimplications of the presence of a ninth planet for the Solar Systemsformation and for the current Inner Oort Cloud

Author(s) Megan E Schwamb Ramon Brasser Zhi-WeiZhang Institution(s) 1 Earth-Life Science Institute (ELSI) TokyoInstitute of Technology 2 Institute of Astronomy amp AstrophysicsAcademia Sinica (ASIAA)

21110 ndash Property of Kozai Dynamics of Inner OortCloud Objects with a Hypothetical Planet BeyondNeptuneThe origin of a number of Trans-Neptunian objects (TNOs) withlarge perihelion and semi-major axis are difficult to explain bycurrent models In addition to Sedna these include 2010 GB174(Chen et al 2013) and 2012 VP113 (Trujillo and Sheppard 2014)which might represent members of the Inner Oort Cloud objects(IOCOs) One thing of particular interest has to do with theclustering of the argument of perihelion (ω) of the discoveredIOCSs near 340 Trujillo and Sheppard (2014) suggested that thiseffect could be caused by the Kozai mechanism induced by adistant planet We have performed parametric studies of the orbitalmotion of hypothetical IOCOs under the influence of this distantplanet Our preliminary results indicate that this distant planet witha perihelion distance of about 150 AU if exists should have a masslarger than 2 Earth masses The observed clustering in theargument of perihelion at around 340 can not be reproduced byour simulations Instead the distribution of ω of the test particlesin the inner Oort cloud is characterized by concentration around 0

or 180 and on the other hand 90 or 270 (for smallerperihelion and lower inclination)

Author(s) Zong-Fu Sie Hsing-Wen Lin Wing-Huen IpInstitution(s) 1 Institute of AstronomyNCU

21111 ndash Deep Surveys for Inner Oort Cloud ObjectsWe are undertaking two deep wide-field surveys to discoverextremely distant solar system objects While our target solarsystem population is the Inner Oort Cloud objects such as 2012VP113 and Sedna we are also sensitive to other populations withhigh perihelia such as the Scattered Kuiper Belt Objects and thehighest perihelion Kuiper Belt Objects which have similararguments of perihelion to the Inner Oort Cloud Objects Theseunusual populations are thought to consist primarily of highly

eccentric objects which spend most of their orbits hundreds orthousands of AU from the sun Large aperture telescopes areneeded to reach the faintness limits red magnitudes of 235 to 25required for detection of even the large members of the populationIn addition wide fields of view are also needed since the skydensity of the detectable members of the populations approach 1 in100 square degrees even with large telescopesOur primary discovery instruments are the Dark Energy Camera(DECam) on the 4 meter Blanco Telescope at the Cerro TololoInter-American Observatory and Hyper Suprime-Cam (HSC) onSubaru Telescope at Maunakea Each of these instruments has atremendously wide field of view considering the size of thetelescope they are mounted on DECam has a field of view of about3 square degrees and HSC has a field of view of about 175 squaredegrees We will present our survey progress in terms of sky areacovered and new objects discovered and highlight some of ourmore interesting findings

Author(s) Chadwick A Trujillo David J Tholen Scott SSheppardInstitution(s) 1 Carnegie Inst 2 Gemini Obs 3 Univ Hawaii

21112 ndash Results from the Pan-STARRS-1 Outer SolarSystem Key ProjectAs part of the Pan-STARRS-1 Outer Solar System Key Project wehave completed two searches of the full data set obtained by thePan-STARRS-1 Science Consortium The data set spans more thanthree years and covers the full sky north of -30 degrees declinationOur two searches employ different algorithms and between themare sensitive to slow-moving objects with magnitudes brighter thanapproximately r=225 and heliocentric distances of 25-250 AU Wepresent the details of our search pipeline the results of oursurveys and plans for future surveys with the ongoingPan-STARRS-1+Pan-STARRS-2 system

Author(s) Matthew J Holman Ying-Tung Chen Hsing-Wen Lin Michael Lackner Matthew J Payne CharlesAlcockInstitution(s) 1 Harvard University 2 Harvard-SmithsonianCfA 3 IAA Academia Sinica 4 National Central University

21113 ndash The IMACS Occultation SurveyWe report the results of our extended campaign to search foroccultations of background stars by small (sub-km) Kuiper beltobjects (KBOs) using the IMACS instrument on the MagellanTelescopeWe implemented a novel shutterless continuous readout mode onthe IMACS instrument with custom-made aperture maskspermitting simultaneous high-speed (~40 Hz) photometry fornumerous stars while minimizing the effects of stellar crowdingand sky background Observing in the southern hemisphere allowsus to target the intersection of the ecliptic and galactic planeswhere hundreds of stars can be monitored with a single field ofviewWe observed for a total of ~28 hours spread over eight nightsobtaining over 10000 star-hours of light curves with per-pointSNR gt 10 This represents an order of magnitude increase in starhours compared to the previous best ground-based survey byBianco et al (2009) Our results allow us to place strongconstraints on the surface density of sub-km objects in theKuiper-Belt as well as to complement the HST FGS results ofSchlichting et al (2009 2012)

Author(s) Matthew John Payne Matthew Holman Charles Alcock David Osip Hilke SchlichtingInstitution(s) 1 Carnegie 2 Harvard-Smithsonian 3 MIT

21114 ndash The Outer Solar System Origins Survey(OSSOS) a status updateOSSOS is a 560 hour imaging survey using MegaPrime on theCFHT designed to produce a well characterized sample of Kuiperbelt objects whose orbital and physical properties will provideuseful constraints on the evolutionary history of the outer solarsystem Started in 2013 this 4 year project has now entered the

2 21

2 12

o

o

o o o o

1 1 1

2 31

2 34 1 2

2

2 22 1 3

47

finally year of survey operation With 12 (84 square degrees) ofthe observation fully analyzed OSOSS has detected and tracked 219TNOs brighter than our typical flux limit of r ~ 245 This is 30more detections than the entire Canada-France Ecliptic PlaneSurvey (CFEPS) a precursor projectBased on the first quarter of the survey the OSSOS project confirmsthe CFEPS-L7 orbital model of the orbital structure of the TNOpopulation (Petit et al 2011) and has provided additional evidenceof complex structure in the size distribution of scatterin TNOs(Shankman et al 2015) A number of the OSSOS science teams arepresenting results at this meeting Bannister et al Benecchi et alFraser et al Volk et al on a variety of aspects of the orbital andphysical properties the OSSOS detected samples Here we present asummary of the current status of the survey field locations basiccharacterization detection rates and some global detectionstatisticsMore details on the OSSOS project are available from our web sitewwwossos-surveyorg

Author(s) J J Kavelaars Michele T Bannister BrettGladman Jean-Marc Petit S Gwyn Ying-Tung Charles Chen Mike Alexandersen Kat VolkInstitution(s) 1 IAA Academia Sinica 2 National ResearchCouncil of Canada 3 Observatoire de Besancon 4 University ofArizona 5 University of British Columbia

21115 ndash Col-OSSOS Colours of the Outer Solar SystemOrigins SurveyThe surfaces of trans-Neptunian objects (TNOs) are poorlyunderstood Other than the large objects which exhibit signaturesof various ices very little has been discerned about thecompositions of most TNOs In recent years some concreteknowledge about the distribution of surface colours of small TNOshas come to light It is now generally accepted that small TNOs fallinto at least three classes of object based on their surface coloursand albedo TNO surface type is also correlated with dynamicalclass with certain types of TNO being found primarily in certainregions of the outer Solar System This correlation presents theintriguing idea that the surfaces of TNOs contain information onmore than composition but as well hold the key to understandingthe dynamical processes that lead to the giant planets violentlydispersing the protoplanetesimal disk and populating the KuiperBelt region It is around this idea that the Col-OSSOS survey ispredicated This 4 year program which started in 2014B issimultaneously using the Gemini-North and Canada-France-Hawaii telescopes to gather near simultaneous u g r and Jspectral photometry of all targets in the Outer Solar System OriginsSurvey (OSSOS) brighter than rrsquo=235 (~140 expected) The focusof Col-OSSOS is completeness and consistency with the sameSNR=25 being reached in all bands for all targets brighter than ourdepth limitCol-OSSOS will provide a combined compositional-dynamical mapfrom which key hypotheses about the Solar Systems cosmogonycan be tested For example by mapping the fraction of TNOs withcold-classical like surface colours we will be able to determine howmuch of the belt was populated by dynamical scattering versussweep-up from Neptune Further we will be able to constrain thecompositional homogeneity of the protoplanetesimal disk Thesurfaces of TNOs must reflect that homogeneity a heterogeneousdisk will result in a clumpy colour distribution with many uniquetypes while a homogeneous disk will result in a smoothdistribution of colours with only a few distinct types Here we willpresent preliminary results and report on the initial progress of thesurvey

Author(s) Wesley Cristopher Fraser Michele Bannister Rosemary Pike Megan Schwamb Michael Marrset JJKavelaars Susan Benecchi Audrey Delsanti Audrey Guilbert-Lepoutre Alex Parker Nuno Peixinho Peirre Vernazza Shiang-Yu WangInstitution(s) 1 CNRS - Laboratoire drsquoAstrophysique deMarseille 2 Institute of Astronomy amp Astrophysics at AcademiaSinica 3 NRC - Herzberg 4 Observatoire de Besancon 5Planetary Science Institute 6 Queens University Belfast 7Southwest Research Institute 8 University of Antofogasta 9University of Victoria

21116 ndash Status of the Transneptunian AutomatedOccultation Survey (TAOS II)The Transneptunian Automated Occultation Survey (TAOS II) willaim to detect occultations of stars by small (~1 km diameter)objects in the Kuiper Belt and beyond Such events are very rare(lt10 events per star per year) and short in duration (~200 ms)so many stars must be monitored at a high readout cadence TAOSII will operate three 13 meter telescopes at the ObservatorioAstronoacutemico Nacional at San Pedro Maacutertir in Baja CaliforniaMeacutexico With a 23 square degree field of view and a high speedcamera comprising CMOS imagers the survey will monitor 10000stars simultaneously with all three telescopes at a nominal readoutcadence of 20 Hz Construction of the site began in the fall of 2013We present here an update on the status of the TAOS II surveyincluding the site development camera fabrication and projectschedule

Author(s) Matthew J Lehner Shiang Yu Wang MauricioReyes-Ruiz You Hua Chu William Lee Zhi Wei Zhang KemH Cook Timothy Norton Andrew Szentgyorgyi CharlesAlcockInstitution(s) 1 Academia Sinica Institute of Astronomy andAstrophysics 2 Harvard-Smithsonian Center for Astrophysics 3Instituto de Astronomia Universidad Nacional Autonoma deMexico 4 Instituto de Astronomia Universidad NacionalAutonoma de Mexico

21117 ndash Pan-STARRS 1 discoveries of new NeptuneTrojans Preliminary resultsNeptune Trojans are a well-known probe of the dynamicalenvironment of the outer solar system However given the smallnumber of known Neptune Trojans many questions remain thetotal number the size distribution and the orbital distribution ofNeptune Trojans are all still unclearPan-STARRS 1 (PS1) survey provides a chance to comprehensivelyinvestigate the properties of Neptune Trojan population In thisstudy we present our preliminary results of a PS1 search for newNeptune Trojans We report several candidates At least oneunstable L5 trojan has been confirmed The preliminary orbitaldistribution of Neptune Trojan populations shows a possible L4L5distribution asymmetry from the combination of our newcandidates and the known Neptune Trojans

Author(s) Hsing-Wen Lin Yin Tung Chen Matthew JHolman Wing-Huen IpInstitution(s) 1 Harvard-Smithsonian Center for Astrophysics2 Institute of Astronomy and Astrophysics Academia Sinica 3Institute of Astronomy National Central University

212 ndash Spiraling in on Ceres and Vesta Redux21201 ndash Spikes in High-Energy Electrons at CeresEvidence for a Bow ShockStrong regular spikes in counts suggestive of electrons weremeasured by by the Dawnrsquos Gamma Ray and Neutron Detector(GRaND) when Dawn was in Survey orbit about Ceres in June2015 The source of the spikes was tentatively identified asenergetic electrons (up to 100 keV) Individual spikes lasted up toan hour and were superimposed on more gradual variationsattributed to energetic ion interactions The spikes occurred duringa period of intense solar activity associated with sunspot AR2371

2 25 3 2 1

1 4

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3 5 14 7 8 1

2

-3

1 13 1 4 1

1 2 22

3 21 3

48

The fact that they were seen at the same location on threesuccessive orbits over a 10 day period suggests that the events areassociated with Ceres Fermi-acceleration of the solar windelectrons could explain the dramatic increase in the electroncounts If a bow shock were present at Ceres electrons could bereflected back into the solar wind and travel along the magneticfield line tangent to the shock and encounter the spacecraft If abow shock is confirmed this would have considerable implicationsfor the existence of an exosphere at Ceres its characteristics andpossible origins The observations to date allow such anatmosphere to be transitory

Author(s) Michaela Villarreal Christopher T Russell Thomas Prettyman Naoyuki Yamashita William FeldmanInstitution(s) 1 Planetary Science Institute 2 UCLA

21202 ndash Spectral modeling of Ceres VIR data fromDawn Method and ResultThe Dawn spacecraft [1] is at Ceres the closest of the IAU-defineddwarf planets to the Sun This work focuses on the interpretation ofCeresrsquo surface composition based on the data from the VIRinstrument [2] onboard Dawn The Visible InfraRed (VIR)mapping spectrometer combines high spectral and spatialresolution in the VIS (025-1mm) and IR (1-5mm) spectral rangesVIR will provide a very good coverage of the surface during itsorbital mission at CeresIn order to model the measured spectra we have utilized Hapkesradiative transfer model [3] which allows estimation of the mineralcomposition the relative abundances of the spectral end-membersand the grain size Optical constants of the spectral end-membersare approximated by applying the methodology described in [4] toIR spectra reflectance obtained from the RELAB databaseThe observed spectra of Ceres surface are affected by a thermalemission component that prevents direct comparison withlaboratory data at longer wavelengths Thus to model the wholewavelength range measured by VIR the thermal emission ismodeled together with the reflectance Calibrated spectra are firstcleaned by removing artefacts A best fit is obtained with a leastsquare optimization algorithm For further details on the methodsee reference [5]The range 25 - 29 μm is severely hindered by Earths atmospherebut it contains a strong absorption band that dominates the IRCeresrsquo spectrum Thanks to the VIR instrument we can obtain acompositional model for the whole IR range [6] We used severaldifferent combinations of materials hypothesized to berepresentative of the Ceresrsquo surface including phyllosilicates icescarbonaceous chondrites and salts The results will be discussedAcknowledgements This work is supported by the Italian SpaceAgencies and NASA Enabling contributions from the DawnInstrument Operations and Science Teams are gratefullyacknowledgedReference[1] Russell et al Space Sci Rev 163 3-23 2011[2] De Sanctis et al Space Sci Rev 163 329-369 2011[3] Hapke Cambridge Univ Press 1993 2012[4] Carli et al Icarus 235 207-219 2014[5] Raponi PhD Thesis arXiv150308172 2015[6] De Sanctis et al Nature submitted 2015

Author(s) Andrea Raponi MC De Sanctis M Ciarniello FG Carrozzo E Ammannito F Capaccioni MT Capria AFrigeri S Fonte M Giardino A Longobardo G Magni SMarchi E Palomba CM Pieters F Tosi D Turrini FZambon CA Raymond CT RussellInstitution(s) 1 Department of Earth Environmental andPlanetary Sciences Brown University 2 IAPS - INAF 3 JetPropulsion Laboratory California Institute of Technology 4University of California Los Angeles Earth Planetary and SpaceSciences

21203 ndash First Geological Mapping Investigation of theKerwan Hemisphere of Ceres (0-180degE) from NASArsquosDawn MissionThe Dawn Science team divided the surface of Ceres into

quadrangles in order to facilitate systematic geological mappingwhich is a tool used to methodically observe and interpret thesurfaces of planetary bodies Here we present a geological map ofthe Kerwan hemisphere of Ceres (0-180degE) which we assemblefrom a combination of quadrangle-scale geological maps CeresrsquoKerwan hemisphere is dominated by smooth plains whichsurround the 284-km-diameter Kerwan crater The smoothmaterial has a lower abundance of craters than other parts of theKerwan hemisphere and may suggest that regional resurfacing hasoccurred The current topography data also indicates that broadpositive topography features are present within Kerwan crater Inaddition there are ejecta deposits surrounding Haulani and Dantucraters which are distinctive in photometrically corrected mosaicsand color composite mosaics These ejecta deposits may contributeto the 1 and 2 bright albedo regions observed by Li et al (2006)with the Hubble Space Telescope In the northern region there arehomogeneously distributed impact craters most of which arecircular shallow flat-floored and contain central moundsPolygonal craters are also observed which may provide inferencesabout the target materials in which they formed In the southernregion there are numerous craters containing central mounds andsmooth material in their interiors For example the 129-km-diameter Zadeni crater contains a broad central mound Moreoverlobate deposits are found in numerous craters in the Kerwanhemisphere which are likely formed by mass wasting Ongoingwork will include the development of a detailed geological historyand the use of crater morphologies to infer the composition andphysical properties of the sub-surface Currently our geologicalmapping is based on Approach (~13 kmpixel) and Survey (~400mpixel) mosaics of clear and color filter data from the Dawnspacecraftrsquos Framing Camera In addition shape models derivedfrom Framing Camera data are used as a mapping aid Dawn willbegin the High Altitude Mapping Orbit (HAMO) in mid-Augustand our geological mapping will then incorporate the higherresolution HAMO mosaics (~140 mpixel)

Author(s) Jennifer E C Scully David A Williams Scott CMest Debra L Buczkowski Ralf Jaumann Carol ARaymond Christopher T Russell Thomas Roatsch FrankPreusker Ryan Park Andreas Natheus Martin Hoffmann Michael Schafer Thomas Platz Paul M Schenk SimoneMarchi David P OBrien Maria C De SanctisInstitution(s) 1 Arizona State University 2 German AerospaceCenter (DLR) 3 Institute of Astrophysics and Space Planetology4 Jet Propulsion Laboratory California Institute of Technology 5Lunar and Planetary Institute 6 Max Planck Institute for SolarSystem Research 7 Planetary Science Institute 8 SouthwestResearch Institute 9 The Johns Hopkins University AppliedPhysics Laboratory 10 University of California Los Angeles

21204 ndash First Geological Mapping Investigation of theOccator Hemisphere of Ceres (180deg-360degE) fromNASArsquos Dawn MissionThe Dawn Science team divided the surface of Ceres intoquadrangles in order to facilitate systematic geological mappingwhich is a tool used to methodically observe and interpret thesurfaces of planetary bodies Here we present a geological mapfrom 180deg - 360degE longitude of Ceres which we assemble from acombination of quadrangle-scale geological maps Geologic unitsare characterized based on physical attributes such as albedomorphology structure color and topography and are related togeologic processes such as volcanism tectonism impact crateringdeposition and weathering This hemisphere is dominated by aheavily cratered terrain with both fresh-looking and putatively-relaxed craters evident Also evident is Occator crater and thefeature known as Spot 5 the brightest of the ldquobright spotsrdquo onCeres Linear structures are prevalent but whether they are formeddue to impact stresses or by internal activity has not yet beendetermined However the numerous polygonal craters suggestsignificant sub-surface fracturing Color data indicates considerablecompositional diversity specifically around Spot 5 as well asaround some of the other craters and associated with some of thelinear structures Variations in crater abundance in different partsof this hemisphere suggest that some type of resurfacing might

2 21 1 1

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2 3 4

4 17 9 2

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6 6 58 7 3

49

have occurred Domical positive relief features are present in someof the craters a 5 km high feature informally known as ldquothepyramidrdquo is also identified Determining the processes by whichthese topographically high features formed is of major interest inthis mapping effort Ongoing work will include the development ofa detailed geological history and the use of crater morphologies toinfer the composition and physical properties of the sub-surfaceCurrently our geological mapping is based on Approach (~13kmp) and Survey (~400 mp) mosaics of clear and color filter datafrom the Dawn spacecraftrsquos Framing Camera In addition shapemodels derived from Framing Camera data are used as a mappingaid Dawn will begin the High Altitude Mapping Orbit (HAMO) inmid-August and our geological mapping will then incorporate thehigher resolution HAMO mosaics (~140 mp)

Author(s) Debra Buczkowski David Williams Scott Mest Jennifer E C Scully Ralf Jaumann Chris T Russell CarolRaymond Thomas Roatsch Frank Preusker Ryan Park Andreas Nathues Martin Hoffmann Michael Schaumlfer ThomasPlatz Paul M Schenk Simone Marchi David P OBrien MCristina De SanctisInstitution(s) 1 Arizona State University 2 DLR 3 JetPropulsion Laboratory Calitfonia Institute of Technology 4Johns Hopkins University Applied Physics Laboratory 5 Lunarand Planetary Institute 6 MPI for Solar System Research 7National Institute of Astrophysics 8 Planetary Science Institute 9Southwest Research Institute 10 UCLA

21205 ndash Origin Hypotheses for Kilometer-ScaleMounds on Dwarf Planet CeresThe Dawn Framing Camera has revealed numerous domical toconical features on Ceres which may have relevance to thepresence and history of near-surface ice These features fall intotwo broad classes large domes 10s to gt100 km in diameterexhibiting 1-5 km of positive relief and small mounds lt10 km indiameter exhibiting sub-kilometer relief Here we propose threehypotheses for the origin of the ~150 small mounds identified thusfar and discuss morphological observations that could supporteach hypothesis as higher resolution data becomes availableHypothesis 1 Kilometer-scale mounds are produced by localizederuption of cryomagma or hydrothermal material Observationaltests Kilometer and sub-kilometer scale albedo variationssub-kilometer flow features on individual mounds localized ventsconical or domical shape Challenge Features are smaller thanconvective plumes expected from thermal evolution modelingHypothesis 2 Kilometer-scale mounds are analogous toterrestrial and martian pingos which grow by drawing liquid waterthrough a silicate matrix as a freezing front propagates downwardObservational tests Mounds occurring on smooth material thatfloods or embays large-scale features little or no local albedovariation no small flows associated with individual moundsdomical or ring-shape concentric or radial fractures on dome orcentral depression Challenge Small Cerean mounds observedthus far are an order of magnitude larger than terrestrial or martianpingosHypothesis 3 Kilometer-scale mounds are rootless conesanalogous to features observed on the surface of volcanic flows involatile-rich regions of Earth and Mars Rootless cones areproduced when layers of fluid material inundate a region localizeddevolatilization of a layer mobilizes clasts to form cone-shapeddeposits Observational tests Mounds on smooth material thatfloods or embays large-scale features conical not domical profilelarge central depressions cones in organized spatial patterns nosmall-scale flows Challenge Low gravity environment andorcryolava composition may be incompatible with this processIn addition to morphological observations VIR data will helpdistinguish between these hypotheses

Author(s) Hanna G Sizemore Thomas Platz Britney ESchmidt Jennifer E C Scully Christopher T Russell Scott CMest David A Crown Mark V Sykes Kynan H G Hughson Heather T Chilton David A Williams Carle M Pieters SimoneMarchi Bryan Travis Carol A RaymondInstitution(s) 1 Arizona State University 2 Brown University3 Georgia Institute of Technology 4 Jet Propulsion Laboratory 5Planetary Science Institute 6 Southwest Research Institute 7University of California Los Angeles

21206 ndash Common Mountain-Building Processes onCeres and PlutoThe Dawn Framing Camera has revealed a unique feature on thesurface of Ceres popularly referred to as the ldquopyramidrdquo It is aroughly conical and flat-topped feature with an elevation of ~5 kmand base diameter of ~20 km The side slopes are roughlyconsistent with an angle of repose one expects of particulatematerial on Earth (which may change with gravity) The pyramid isalso notable for its striations down its side over half of itscircumference These striations sharply terminate at the base of thecone without a distinctive talus deposit including an adjacentcrater Recently released images of Norgay Montes and a secondmountain chain in Tombaugh Regio on Pluto by the New Horizonsmission reveal mountains with strikingly similar morphologieswith the Ceres pyramid They are of similar size to within a factor ofa few We investigate the hypothesis that there may be a commonmechanism giving rise to these features on the two dwarf planetsGiven their significantly different heliocentric distances theremarkable ongoing widespread processing of the surface of Plutoand increasing evidence of relatively recent activity in some areas ofCeres interior processes such as plume activity or tectonics may beresponsible A comparative study of uplift morphology on the twodwarf planets may also lend insights into heat production andretention on such bodies throughout the solar system

Author(s) Mark V Sykes Michael Bland Debra LBuczkowski William Feldman Martin Hoffmann KynanHughson Ralf Jaumann Scott King Lucille LeCorre Jian-Yang Li Scott Mest Andreas Natheus David OBrien Thomas Platz Thomas Prettyman Carol Raymond VishnuReddy Ottaviano Reusch Christopher T Russell PaulSchenk Hanna Sizemore Britney Schmidt Bryan TravisInstitution(s) 1 Deutsches Zentrum fuumlr Luft- und Raumfahrt 2Georgia Institute of Technology 3 Jet Propulsion Laboratory CalTech 4 JHUAPL 5 Lunar and Planetary Institute 6 Max PlanckInstitute for Solar System Research 7 NASA GSFC 8 PlanetaryScience Institute 9 UCLA 10 USGS 11 Virginia Tech

21207 ndash The fate of Ceres original crustThe bulk density of Ceres implies that water ice comprises asubstantial fraction of Ceresrsquo interior However water ice is notstable at Ceres orbital distance and if exposed would have a lossrate of 1 km Myr or more The near-hydrostatic shape of Ceresand relatively low melting point of ice suggests that the interior is atleast partly differentiated Because Ceresrsquo surface remains exposedto space it radiates very effectively and models predictingdifferentiation retain an undifferentiated crust This would bedenser than the ice shell beneath it resulting in an unstablestratification This has led to expectations that the crust wouldfounder and the surface of Ceres might be very smooth andrelaxed But could the crust have remained to the present dayHere we model global-scale overturn on Ceres using bothanalytical two-layer linear stability analyses and numerical modelsto predict the most unstable wavelength and growth timescales forRayleigh-Taylor instabilities We find that for a 10 km-thick crustabove a 75 km-thick ice layer instabilities grow fastest at sphericalharmonic degree l=4 The growth timescale is a function of theviscosity of the upper layer This timescale is less than the age ofthe solar system unless the effective viscosity of the crust is gt 10Pa s We conclude that the crust of Ceres could remain at thesurface if it either has some finite elastic strength over a ~800 kmlength scale or is an unconsolidated regolith with a large (gt 50)macro-porosity such that the regolith is buoyant relative to waterice

4 1 83 2 10

3 2 2 36 6 6

6 5 9 87

5 53 4 7

5 5 5 73 1 2

6 5 4

8 104 8 6

9 1 11 88 8 6 86 8 3

8 7 95 8 2 8

-1

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Neither end-member for the crustal strength precludes convectiveactivity in the underlying ice layer However we note that a thickporous regolith is a fantastic insulator and may promote heating ofthe interior and potential foundering of the regolith if the top of theice becomes too warm This possibility can be evaluated by modelsof thermal evolution (eg Castillo-Rogez et al 2010) An episodeof global overturn may have been preserved as spatially correlatedlong-wavelength (l=3-5) variations in albedo composition andtopography which could be measured by Dawn

Author(s) James H Roberts Andrew S RivkinInstitution(s) 1 Johns Hopkins University Applied PhysicsLaboratory

21208 ndash Post-Impact Cryovolcanism and the BrightSpots on CeresThe bright spots on Ceres recently found by NASArsquos Dawn missionhave defied easy explanation The spots are young because the 90km diameter crater in which they are found generally lackssuperposed craters but the composition is equivocal The very highalbedo contrasting on Ceresrsquo dark surface suggests ice but thespots could be salt deposits In either case formation via watervolcanism is plausible either as ice or a salty sublimate Theseobservations pose the problem How can there be recentcryovolcanic processes on a relatively low mass and density bodythat thus has a small complement of long lived radiogenic isotopes(the only plausible heat source) Here we suggest the spots are aconsequence of the impact process Ceresrsquo low bulk densityindicates abundant water ice yet spectra indicate a non-volatilesurface Various interior models predict full or partialdifferentiation which means that the near surface is structured as alargely icy layer covered by a non-volatile layer of unknownthickness For a sufficiently thick layer (gt 5-10 km) the formationof a 90 km crater will not penetrate this layer however the flowfield associated with transient crater collapse may extend into theunderlying icy material to give final crater morphologicalcharacteristics consistent with an icy surface Deposition of impactheat would primarily be in this non-volatile layer which wouldthen diffuse away including some downwards We have performedfinite element simulations of this diffusion finding that for anon-volatile layer ~10 km thick this downward diffusion can leadto supra-melting temperatures in the underlying icy material from01 to 10 Myr after the impact leading to the deposits Thisphenomenon might explain why bright spots are not abundant thecrater needs to be the right size relative to layer thickness theimpact would likely need to occur at a high strike angle (for thedeepest deposition of impact heat) and any resultant depositscould be ephemeral consistent with the craterrsquos apparent veryyoung age Additionally no special conditions are needed for theevolution of Ceres instead these bright spots result from the mostcommon geological process in the solar system impact

Author(s) Andrew J Dombard Saman Karimi Paul MSchenkInstitution(s) 1 Lunar and Planetary Institute 2 Univ ofIllinois at Chicago

21209 ndash Dawn Missionrsquos Search for satellites at CeresUpper limits on size of orbital objectsHundreds of asteroids have small secondary satellites or aredouble or even multiple body systems yet dwarf planet Ceresdoesnrsquot and isnrsquot Ground-based and space-based telescopicsearches have placed upper limits on the size of any secondarybodies gravitationally bound to Ceres of 1-2 km (Gehrels et al 1987Bieryla et al 2011) The Dawn projectrsquos satellite working groupdesigned and conducted a search during approach to Ceres andduring high orbit concentrating its search close to Ceresrsquo limbwhere previous searches could not reach Over 2000 images forboth science and optical navigation were searched In addition adedicated satellite search was conducted during two commandedoff-nadir pointings The acquired images extend 55deg x 55deg oneither side of Ceres at a range of ~ 145000 km and solar phaseangle at Ceres of 18deg No moving objects associated with Ceres weredetected The search extended down to Ceresrsquo limb (previous

searches went to 500 km above the limb) and extended the upperlimit for the non-detection to 30 +- 6 and 45 +-9 meter radius foreffective exposure times of 114s and 19s respectively An additionalsmall search was conducted using the spacecrafts star tracker fromwhich no objects were found The Dawn missionrsquos search reducedthe previous detection limit from Hubble Space Telescope imagesby two orders of magnitude Why some asteroids have satellitesand others donrsquot is a matter for dynamical speculation

Author(s) Lucy-Ann A McFadden David R Skillman Nargess Memarsadeghi Uri Carsenty Stefan E Schroeder Jian-Yang Y Li Marc D RaymanInstitution(s) 1 DLR 2 JPL 3 NASAGSFC 4 PSI

21210 ndash Physical Properties of Ceres from the DawnMissionThe physical parameters of Ceres are determined from processingthe images and radio tracking data acquired during the Approachand Survey phases of the Dawn mission The images with spatialresolution ranging from 8 km to 400 meters were processed usinga stereophotoclinometry method The radiometric tracking datawere processed through precision orbit determination togetherwith landmarks derived from the stereophotoclinometry shapereconstruction Combining the mass and volume values gives thebulk density of 2161 kgm which implies a mixture of silicateswith lighter materials Analyzing the second degree gravity fieldshows that the rotation of Ceres is very nearly about a principalaxis the degree 2 gravity field is consistent with hydrostaticequilibrium and the magnitude of J2 combined with thehydrostatic assumption implies some degree of centralcondensation

Author(s) Ryan Park Alexander Konopliv Bruce Bills Andrew Vaughan Carol Raymond Chris RussellInstitution(s) 1 Jet Propulsion Laboratory 2 UCLA

21211 ndash Ceres Evolution From ThermodynamicModeling and Telescope to Dawn OrbitalObservationsThermodynamic modeling indicated that Ceres has experiencedplanetary processes including extensive melting of its ~25 waterand differentiation (McCord and Sotin JGR 2005 Castillo andMcCord Icarus 2009) Early telescopic studies showed Ceresrsquosurface to be spectrally similar to carboneous-chondrite-likematerial ie aqueously altered silicates darkened by carbon with awater-OH-related absorption near 306 microm Later observationsimproved the spectra and suggested more specific interpretationsStructural water in clay minerals phyllosilicates perhapsammoniated iron-rich clays carbonates brucite all implyingextensive aqueous alteration perhaps in the presence of CO Telescopic observations and thermodynamic models predictedDawn would find a very different body compared to Vesta (egMcCord et al SSR 2011) as current Dawn observations areconfirming Ceresrsquo original water ice should have melted early in itsevolution with the resulting differentiation and mineralizationstrongly affecting Ceresrsquo composition size and shape over timeThe ocean should have become very salty and perhaps may still beliquid in places The surface composition from telescopes seems toreflect this complex history The mineralization with repeatedmixing of the crust with the early liquid interior and with in-fallfrom space would create a complex surface that will present aninterpretation challenge for Dawn The Dawn spacecraft iscurrently collecting observations of Ceresrsquo landforms elementaland mineralogicalmolecular composition and gravity field fromorbit Early results suggest a heavily cratered but distorted andlumpy body with features and composition consistent with internalactivity perhaps recent or current associated with water andperhaps other volatiles We will present and interpret the latestDawn Ceres findings and how they affect our earlier understandingof Ceres evolution from modeling and telescope observations

1 1

2 21

3 33 1 1

4 2

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51

Author(s) Thomas B McCord Jean Philippe Combe JulieC Castillo-Rogez Carol A Raymond Maria Cristina De Sanctis Ralf Jaumann Eleonora Ammannito Christopher RussellInstitution(s) 1 1 Istituto di Astrofisica e Planetologia Spaziali ndashINAF 2 DLR Institute of Planetary Research 3 Jet PropulsionLaboratory 4 The Bear Fight Institute 5 University of Californiaat Los Angeles

21212 ndash Arruntia Crater A Rare Window into VestarsquosNorthern HemisphereOne of the intriguing results of the Dawn mission to Vesta was thediscovery that the only deposits containing significant olivine a keymineralogic indicator of primitive materials occur in two shallowcraters in the northern hemisphere Numerous investigations intothese exposures using either the Framing Camera (FC) or the VIRspectrometer typically find similarities between the olivineoutcropping in Belliciarsquos wall and in the Arruntia ejecta Our owninvestigations ndash using a hybrid VIR-FC approach ndashsuggest animportant distinction between the exposures at the two cratersSpecifically we find that the proximal Arruntia ejecta aredominated not by an olivine-rich component (although isolatedexamples occur) but instead by a more evolved eucriticcomponent These interspersed eucritic materials are similar toolivine-rich materials in FC data because both components pull the1 um band to longer wavelengths Ultimately however they aredistinguished by the position and strength of the 2 um band whichis not covered by FC wavelengths The Arruntia ejecta also appearolivine-like in some parameterizations of VIR spectra for the areabut closer examination of the full spectra at a fine spatial scaleclearly suggests the presence of two different materialsInterestingly the approach used here also reveals a separatediogenitic component in the distal Arruntia ejecta as well as inisolated locations within Arruntiarsquos wall Initial evaluation ofstratigraphic relationships in the Arruntia ejecta suggest apre-impact sequence of eucrite ndashgt olivine-rich -gt diogenite gradingfrom depth to the shallowest subsurface (although the small size ofArruntia means that this entire assemblage was excavated from nomore than a few of kilometers below the surface) These resultsillustrate two main points first that pyroxene-bearing materialsrich in olivine are difficult to distinguish from evolved pyroxenes inthe absence of full resolution spectroscopy at a fine spatial scaleSecond we find that Arruntia crater is likely a unique location onVesta where pervasive mechanical gardening has not yet maskedthe stratigraphic relationships between endmember diogenitic andeucritic components nor olivine-enhancements

Author(s) Jessica Sunshine Leah CheekInstitution(s) 1 University of Maryland

21213 ndash DAWN observations of Vesta versuslunar-type space weatheringThe major reason for spectral changes in lunar-type spaceweathering is production of nanophase iron (npFe ) in the lunarregolith The spectral changes include attenuation of silicateabsorption bands darkening and slope change (reddening)Spectral observations of the asteroid Vesta by DAWN missionrevealed a different pattern The darkening and the absorptionband attenuation occur in similar way as on the Moon Thereddening however is not apparent Thus is space weathering onVesta different from that we see on the MoonIn order to study effects of npFe on thereflectance spectrapyroxene (En 90) and howardite (NWA 1929) powder sampleswere subjected to the space weathering experiments Both enstatiteand howardite show progressive changes in their spectra as afunction of the increasing npFe amount An interesting feature isobserved in the comparison of the slope over the 1 and 2 microm bandsin both pyroxene and howardite While the slope over 2 microm bandshow progressive reddening with increasing npFe amount(similarly to olivine) the situation is reversed in the 1 microm bandregion The relative reduction in the spectral slope is observed inthis regionThis is due to the fact that the decrease in reflectance when addingnpFe is a nonlinear process where higher reflectance values willdecrease more than lower values If the original slope is positive as

the slope over the 1 microm band in pyroxene and howardite the slopewill flatten with increasing npFe (relative bluing)This finding can potentially explain some of the space weatheringobservations for Vesta The majority of the DAWN observationswere done in the 1 microm region where the lack of reddening isobserved similar to our pyroxene and howardite results Thus thelack of reddening over the 1 microm region as observed on Vesta doesnot contradict the space weathering mechanism driven by thepresence of npFe In order to confirm this more NIR data fromVesta are needed over the 2 microm region where our experimentspredict progressive reddening

Author(s) Tomas Kohout Ondrej Malina Antti Penttila Anni Kroger Daniel Britt Jan Fillip Karri Muinonen RadekZborilInstitution(s) 1 Department of Physics University of CentralFlorida 2 Department of Physics University of Helsinki 3Regional Centre of Advanced Technologies and MaterialsDepartments of Physical Chemistry and Experimental PhysicsPalacky University Olomouc

213 ndash Asteroid Surfaces21301 ndash Investigating Hydroxyl at Asteroid 951GaspraRecent investigations [Granahan 2011 2014] of Galileo NearInfrared Mapping Spectrometer (NIMS) observations of asteroid951 Gaspra have detected an infrared absorption feature near 28micrometers These were detected in NIMS data acquired by theGalileo spacecraft on October 29 1991 at wavelengths ranging from07 ndash 52 micrometers [Carlson et al 1992] This abstract presentsa summary of the investigation to identify the material creating the28 micrometer spectral absorption feature The current best matchfor the observed 951 Gaspra feature is the phyllosilicate boundhydroxyl signature present in a thermally desiccated QUE 99038carbonaceous chondrite as measured by Takir et al [2013]The 951 Gaspra absorption feature has been compared to a varietyof hydroxyl bearing signatures Many phyllosilicates hydroxylbearing minerals have absorption minima at different positions(27 or 285 micrometers) It also differs from similar absorptionsin a potential R chondrite analog LAP 04840 The spectra LAP04840 has a 27 micrometer feature due to biotite and a 29micrometer feature due to adsorbed water [Klima et al 2007] 28micrometer absorption minima have been found for adsorbedhydroxyl on the Moon [McCord et al 2011] and variouscarbonaceous chondrites [Calvin and King 1997 Takir et al2013] The best match with a minimum Euclidean distancedifference to the 951 Gaspra feature is found in the spectrum ofQUE 99038 [Takir et al 2013] This spectrum is the product of aninfrared measurement of a sample that had its adsorbed waterbaked off and removed in a vacuum chamber The remaininghydroxyl in the sample belongs to a mixture of phyllosilicatesdominated by the presence of cronstedtiteReferences Calvin W M and T V King (1997) Met Planet Sci32 693-702 Carlson R W et al (1992) Bull American AstroSoc 24 932 Granahan J C (2011) Icarus 213 265-272Granahan J C (2014) 45th LPSC 1092 Klima R C et al(2007) 38th LPSC 1710 McCord T B et al (2011) JGR 116E00G05 Takir D et al (2013) Met Planet Sci 48 1618ndash1637

Author(s) James C GranahanInstitution(s) 1 Leidos

21302 ndash Potentially hazardous asteroid (214869) 2007PA8 The missing link between H chondrites and theouter asteroid beltWe report near-infrared spectra (07-255 μm) of potentiallyhazardous asteroid (PHA) (214869) 2007 PA8 obtained with theNASA Infrared Telescope Facility during its close approach to Earthon November 2012 A detailed mineralogical analysis of this objectwas performed using the measured band parameters along withlaboratory spectral calibrations We found that 2007 PA8 is aQ-type asteroid with an H chondrite-like composition The olivine-

4 43 3 1

2 5 5

1 1

0

0

0

0

0

0

0

2 3 22 1 3 2

3

1

52

pyroxene abundance ratio was estimated to be 47 Wedetermined that the olivine and pyroxene chemistries of thisasteroid are Fa (Fo ) and Fs respectively The low olivineabundance and the location of the band parameters close to theH4 and H5 chondrites suggest that this object originated in theupper middle layers of a larger body that experienced certain degreeof thermal metamorphism The orbit of 2007 PA8 places the sourceregion of this asteroid in the outer part of the main belt Due to itsproximity to the J52 resonance low orbital inclination andcompositional affinity we determined that 2007 PA8 originated inthe Koronis family

Author(s) Juan Andres Sanchez Vishnu Reddy MelissaDykhuis Sean Lindsay Lucille Le CorreInstitution(s) 1 Atmospheric Oceanic and Planetary PhysicsUniversity of Oxford 2 Lunar and Planetary LaboratoryUniversity of Arizona 3 Planetary Science Institute

21303 ndash The Shape of Near-Earth Asteroid 275677(2000 RS11) From Inversion of Arecibo and GoldstoneRadar ImagesWe observed near-Earth asteroid 2000 RS11 with the Arecibo andGoldstone planetary radars during a 0035 au approach in March2014 obtaining delay-Doppler images between March 13 andMarch 17 The finest-resolution images have range resolution of75 mpixel and show that RS11 is a contact binary with complextopography We used the SHAPE software package (Magri et alIcarus 186 156ndash160 2007) to create a physical model of RS11 andits spin state from these delay-Doppler imagesThe rotation period of RS11 is well constrained from opticallightcurves P = 4444 plusmn 0001 h (Warner et al Minor PlanetBulletin 41 160 2014 and Benishek Minor Planet Bulletin 41 2572014) We found two possible pole directions and correspondingshape models mirror images of one another which provide equallygood fits to the radar data RS11rsquos pole direction is either (λ β) =(155deg 30deg) plusmn 10deg or (335deg -30deg) plusmn 10deg in J2000 eclipticcoordinates The most likely pole directions of RS11 are not alignedwith the heliocentric orbit normal and instead have an obliquitywithin 10deg of 56deg or 124degOur best-fit shape models are 1400-vertex polyhedra comprisingtwo lobes in contact The lengths of RS11rsquos principal axes are 698 plusmn71 m 578 plusmn 59 m and 758 plusmn 77 m RS11 has a volume of 0086 plusmn0026 km^3 The long axis of RS11rsquos larger lobe is 751 plusmn 77 m andthe long axis of the smaller lobe is 398 plusmn 41 m the volume ratiobetween these lobes is roughly 27 plusmn 10 Spectral data informs usthat RS11 is an S-class object (Lazzarin et al Icarus 169 3792004)RS11s shape is unusual compared with those of other contactbinary NEAs imaged by radar Its larger lobe is flattenedAdditionally while the neck between the smaller and larger lobes ofmost contact binaries is located near the larger lobes longestprincipal axis (such as in the cases of 25143 Itokawa and 4179Toutatis) RS11s neck is near its larger lobes shortest principalaxis RS11 is the first asteroid of this type for which we have a shapemodel

Author(s) Kaley Brauer Michael W Busch Lance AMBenner Marina Brozovic Ellen S Howell Michael C Nolan Alessondra Springmann Jon D Giorgini Patrick A Taylor Joseph S JaoInstitution(s) 1 Arecibo Observatory 2 Brown University 3Jet Propulsion Laboratory California Institute of Technology 4Lunar amp Planetary Laboratory University of Arizona 5 SETIInstitute

21304 ndash Thermophysical Model of S-complex NEAs1627 IvarWe present updates to the thermophysical model of asteroid 1627Ivar Ivar is an Amor class near Earth asteroid (NEA) with ataxonomic type of Sqw [1] and a rotation rate of 4795162 plusmn 54 10 hours [2] In 2013 our group observed Ivar in radar in CCDlightcurves and in the near-IRrsquos reflected and thermal regimes (08ndash 41 microm) using the Arecibo Observatoryrsquos 2380 MHz radar thePalmer Divide Stationrsquos 035m telescope and the SpeX instrument

at the NASA IRTF respectively Using these radar and lightcurvedata we generated a detailed shape model of Ivar using thesoftware SHAPE [34] Our shape model reveals more surfacedetail compared to earlier models [5] and we found Ivar to be anelongated asteroid with the maximum extended length along thethree body-fixed coordinates being 12 x 1176 x 6 km For ourthermophysical modeling we have used SHERMAN [67] withinput parameters such as the asteroidrsquos IR emissivity opticalscattering law and thermal inertia in order to complete thermalcomputations based on our shape model and the known spin stateWe then create synthetic near-IR spectra that can be compared toour observed spectra which cover a wide range of Ivarrsquos rotationallongitudes and viewing geometries As has been noted [68] theuse of an accurate shape model is often crucial for correctlyinterpreting multi-epoch thermal emission observations We willpresent what SHERMAN has let us determine about the reflectivethermal and surface properties for Ivar that best reproduce ourspectra From our derived best-fit thermal parameters we will learnmore about the regolith surface properties and heterogeneity ofIvar and how those properties compare to those of other S-complexasteroids References [1] DeMeo et al 2009 Icarus 202 160-180[2] Crowell J et al 2015 LPSC 46 [3] Magri C et al 2007 Icarus186 152-177 [4] Crowell J et al 2014 AASDPS 46 [5]Kaasalainen M et al 2004 Icarus 167 178-196 [6] Crowell J etal 2015 TherMoPS II [7] Howell E et al 2012 AASDPS 44 [8]Howell E et al 2015 TherMoPS II This work is partiallysupported by NSF (AST-1109855) NASA (NNX13AQ46G) CLASS(NNA14AB05A) and USRA (06810-05)

Author(s) Jenna L Crowell Ellen S Howell ChristopherMagri Yan R Fernandez Sean E Marshall Brian D Warner Ronald J VervackInstitution(s) 1 Center for Solar System Studies - Palmer DivideStation 2 Cornell University 3 LPLUniversity of Arizona 4The Johns Hopkins University Applied Physics Laboratory 5University of Central Florida 6 University of Maine atFarmington

21305 ndash Using Simple Shapes to Constrain AsteroidThermal InertiaWith the use of remote thermal infrared observations and athermophysical model (TPM) the thermal inertia of an asteroidsurface can be determined The thermal inertia in turn can beused to infer physical properties of the surface specifically toestimate the average regolith grain size Since asteroids are oftennon-spherical techniques for incorporating modeled(non-spherical) shapes into calculating thermal inertia have beenestablished However using a sphere as input for TPM is beneficialin reducing running time and shape models are not generallyavailable for all (or most) objects that are observed in thethermal-IR This is particularly true as the pace of infraredobservations has recently dramatically increased notably due tothe WISE mission while the time to acquire sufficient light curvesfor accurate shape inversion remains relatively long Here weinvestigate the accuracy of using both a spherical and ellipsoidalTPM with infrared observations obtained at pre- andpost-opposition (hereafter multi-epoch) geometries to constrainthe thermal inertias of a large number of asteroidsWe test whether using multi-epoch observations combined with aspherical and ellipsoidal shape TPM can constrain the thermalinertia of an object without a priori knowledge of its shape or spinstate The effectiveness of this technique is tested for 16 objectswith shape models from DAMIT and WISE multi-epochobservations For each object the shape model is used as input forthe TPM to generate synthetic fluxes for different values of thermalinertia The input spherical and ellipsoidal shapes are then steppedthrough different spin vectors as the TPM is used to generatebest-fit thermal inertia and diameter to the synthetically generatedfluxes allowing for a direct test of the approachrsquos effectiveness Wewill discuss whether the precision of the thermal inertia constraintsfrom the spherical TPM analysis of multi- epoch observations iscomparable to works that use non-spherical shapes The findingspresented at the conference will be discussed in relation to worksthat also use different shape models (ie sphere lightcurve andradar-derived shapes) to perform TPM analyses on asteroid

18 82 16

3 32 1 3

2 53 3 4 4

4 3 13

-6

5 36 5 2 1

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53

thermal data

Author(s) Eric M MacLennan Joshua P EmeryInstitution(s) 1 The University of Tennessee

21306 ndash Near-Infrared Spectroscopy of TrojanAsteroids Assessing Compositional Bimodality atSmall SizesThe Trojan asteroids orbit the sun within Jupiterrsquos gravitationallystable Lagrange points (L4 and L5) Their unique orbits make themprime targets for study by which to further our understanding ofthe evolution of the Solar System The formation scenario that bestfits their orbital properties comes from the Nice model whichpredicts that the Trojan asteroids originally formed in the KuiperBelt and were trapped in Jupiterrsquos Lagrange regions during theperiod of giant-planet-migration-induced instability Compositionsof Trojans offer a test of this prediction Although the featurelessspectra observed previously in the near-infrared (NIR 07ndash25 μm)preclude compositional determination further analysis of thespectral slopes for these data revealed two distinct spectral groupsThe bimodality of Trojans is defined by the degree of spectralreddening in which two-thirds of Trojans exhibit redder spectrawith the remaining one-third exhibiting less-red spectra PreviousNIR observations of the Trojan asteroids to assess compositionalgroups focused on the largest objects Those observations includedall Trojans with diameter (gt75 km but an incomplete census atsmaller sizes) This study aims to determine whether thebimodality observed in large Trojans is also present for smallTrojans (lt75 km) We have observed 17 small Trojans residingwithin Jupiterrsquos L5 Lagrange point (ranging in diameter from ~ 39km to ~ 75 km) using the SpeX spectrograph at NASArsquos InfraredTelescope Facility We have reduced these data and extracted theircorresponding spectra We will analyze the spectral slopes of theseobjects in the context of previous results on Trojan spectral groupsSuch analysis will help further our understanding of the origins ofTrojan asteroids from where they may have originated andpossibly provide a unique perspective into the evolution of theSolar System

Author(s) Nicholas C Stamper Joshua P Emery MichaelP Lucas Richard J CartwrightInstitution(s) 1 University of Tennessee

21307 ndash Explaining Space-Weathering Effects onUV-Vis-NIR Spectra with Light-Scattering MethodsSpace-weathering (SW) introduces changes to the asteroidreflectance spectra In silicate minerals SW is known to darken thespectra and reduce the silicate absorption band depths In olivinethe neutral slope in Vis and NIR wavelengths is becoming positive[1] In pyroxene the positive slope over the 1 microm absorption bandis decreasing and the negative slope over the 2 microm band isincreasing towards positive values with increasing SW [2]The SW process generates small nanophase iron (npFe )inclusions in the surface layers of mineral grains The inclusionsare some tens of nm in size This mechanism has been linked to theMoon and to a certain extent also to the silicate-rich S-complexasteroidsWe offer two simple explanations from light-scattering theory toexplain the SW effects on the spectral slope First the npFe willintroduce a posititive general slope (reddening) to the spectra ThenpFe inclusions (~10 nm) are in the Rayleigh domain with thewavelength λ in the UV-Vis-NIR range Their absorption cross-section follows approximately the 1λ-relation from the Rayleightheory Absorption is more efficient in the UV than in the NIRwavelengths therefore the spectra are reddeningSecond the effect of npFe absorption is more efficient fororiginally brighter reflectance values Explanation combines theeffective medium theory and the exponential attenuation in themedium When adding a small amount of highly absorbing npFe the effective absorption coefficient k will increase approximatelythe same Δk for the typical values of silicates This change willincrease more effectively the exponential attenuation if the originalk was very small and thus the reflectance high Therefore bothpositive and negative spectral slopes will approach zero with SW

We conclude that the SW will introduce a general reddening andneutralize local slopes This is verified using the SIRIS code [3]which combines geometric optics with small internal diffusescatterers in the radiative transfer domain[1] Kohout T et al (2014) Icarus 237(15) 75ndash83[2] Kohout T et al (2015) Workshop on Space Weathering ofAirless Bodies Abstract[3] Muinonen K et al (2009) JQSRT 110 1628ndash1639

Author(s) Antti Penttilauml Timo Vaumlisaumlnen JuliaMartikainen Tomas Kohout Karri MuinonenInstitution(s) 1 University of Helsinki

21308 ndash Comparing the Data-reduction Methods forPhotometric ModelingPhotometric models describe the light scattering properties of theasteroidrsquos surface providing clues for the physical properties of thesurface and photometric correction for comparisons betweendifferent area on asteroids and laboratory measurements Differenttechniques have been widely used to reduce the photometric datafor modeling purposes including different sampling methods suchas average of each image or keep only four-corners or center areaof each image The purpose of this work is to compare thesetechniques analyzing their different effect on photometricmodeling and photometric corrections to spectrophotometric dataOur goal is to identify which data-reduction method is the bestapproach to retrieve the true photometric properties of planetarysurface and generate the most credible photometric correctionsUsing a set of image data from the Near Earth Asteroid Rendezvous(NEAR) Spacecraftrsquos Multi-Spectral Imager (MSI) we find that thedifferent approaches produce similar results but they tend toperform differently when the data set is with different quality

Author(s) Xiaoduan Zou Jian-Yang Li Beth Ellen ClarkInstitution(s) 1 Ithaca College 2 Planetary Science Institute

21309 ndash Shape and topography corrections forplanetary nuclear spectroscopyThe elemental composition of planetary surfaces can bedetermined using gamma ray and neutron spectroscopy Mostplanetary bodies for which nuclear spectroscopy data have beenacquired are round and simple analytic corrections formeasurement geometry can be applied however recentmeasurements of the irregular asteroid 4 Vesta by Dawn requiredmore detailed corrections using a shape model (Prettyman et alScience 2012) In addition subtle artifacts of topography have beenobserved in low altitude measurements of lunar craters withpotential implications for polar hydrogen content (Eke et al JGR2015) To explore shape and topography effects we have updatedthe general-purpose Monte Carlo radiation transport code MCNPXto include a polygonal shape model (Prettyman and HendricksLPSC 2015) The shape model is fully integrated with the codersquos 3Dcombinatorial geometry modules A voxel-based accelerationalgorithm enables fast ray-intersection calculations needed forMonte Carlo As modified MCNPX can model neutron and gammaray transport within natural surfaces using global andor regionalshapetopography data (eg from photogrammetry and laseraltimetry) We are using MCNPX to explore the effect ofsmall-scale roughness regional- and global-topography forasteroids comets and close-up measurements of high-relieffeatures on larger bodies such as the lunar surface MCNPX cancharacterize basic effects on measurements by an orbitingspectrometer such as 1) the angular distribution of emittedparticles 2) shielding of galactic cosmic rays by surrounding terrainand 3) re-entrant scattering In some cases re-entrant scatteringcan be ignored leading to a fast ray-tracing model that treats effects1 and 2 The algorithm is applied to forward modeling and spatialdeconvolution of epithermal neutron data acquired at VestaAnalyses of shapetopography effects and correction strategies arepresented for Vesta selected small bodies and cratered planetarysurfaces

Author(s) Thomas H Prettyman John S HendricksInstitution(s) 1 Planetary Science Institute 2 Techsource Inc

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21310 ndash Spectral bluing on 101955 Bennu andimplications for dynamics of sub micron regolithgrains on asteroidsC and B class asteroids (including 101955 Bennu the destination ofthe OSIRIS REx mission) display spectral bluing in the visible(Lantz et al 2013) This spectral bluing effect has been found to betemporally variable on Bennu (Binzel et al 2015) Binzel et alsuggested this is due to a fining of the ~45 micron grain sizefraction which causes spectral reddening This finer grain size ofthe ~45 micron fraction may be associated with regolith migrationduring formation of Bennus equatorial ridgeIn Brown (2014) the effect of grain size and optical index on thealbedo of small conservative and absorbing particles as a functionof wavelength was examined The conditions necessary formaximization of spectral bluing effects in real-world situationswere identifiedThe spectral bluing to be discussed in this presentation was presentin the Lantz et al spectra but not the Binzel et al spectrasuggesting that in addition to finer grain ~45 micron material adecrease in the sub micron grain sized fraction has taken place asBennus sub-Earth latitude changed between these observationsObservations of this effect may provide the strongest test yet forcohesive regolith models (eg Rositis et al 2014)In this presentation I will discuss 1) the evidence for spectralbluing on 101955 Bennu (in particular) and other bodies in oursolar system and 2) the implications of how the OVIRS instrumenton OSIRIS-REx may be used to determine the spatial variability ofthis spectral feature on Bennu and 3) the potential for OVIRS toaugment our understanding of the dynamics of sub micronmaterial on asteroidsRefsBinzel R P et al Spectral slope variations for OSIRIS-REx targetAsteroid (101955) Bennu Possible evidence for a fine-grainedregolith equatorial ridge Icarus 256 (2015) 22-29Brown Adrian J ldquoSpectral Bluing Induced by Small Particles underthe Mie and Rayleigh Regimesrdquo Icarus 239 (2014) 85ndash95Lantz C et al ldquoEvidence for the Effects of Space WeatheringSpectral Signatures on Low Albedo Asteroidsrdquo AampA 554 (2013)138Rositis B et al Cohesive forces prevent the rotational breakup ofrubble-pile asteroid (29075) 1950 DA Nature (2014) 174-176

Author(s) Adrian J BrownInstitution(s) 1 SETI Institute

21311 ndash SHERMAN A Shape-based ThermophysicalModel for Near-Earth AsteroidsWe have developed a thermophysical model SHERMAN whichcan produce temperature distributions and thermal fluxes forairless bodies Although intended for near-Earth asteroids (NEAs)it has applications to the Moon and may be adapted for othersituations SHERMAN is based on the asteroid shape modelingcode developed by Hudson (1993) and enhanced by Magri et al(2007 2011) The input model asteroid can have an arbitrary shapedescribed as a polyhedral solid with triangular facets The userspecifies a spin state which can include non-principal axis rotationThe asteroid orbit and positions of the Sun and Earth are input sothat the proper heating and viewing geometry of the object areused The user specifies the optical scattering law IR emissivitythermal inertia specific heat density and conductivity all of whichare permitted to vary across the surface if desired We have appliedthis model to relative reflectance observations of NEAs with a widerange of compositions sizes and shapes in order to determine howmuch these properties can affect the thermal emission We haveselected objects that are also observed with radar so that the shapeand spin state is known at least to some extent We find thatirregular shapes can significantly affect the surface temperaturedistribution Observations at several different viewing geometriescan rarely be fit by a single set of thermal parameters unless thedetailed shape spin and surface properties are included Wepresent results using this model and discuss future applications tobetter understand the nature of asteroid surfaces

Author(s) Ellen S Howell Christopher Magri Ronald JVervack Yanga R Fernandez Michael C Nolan Patrick ATaylor Sean E Marshall Jenna L CrowellInstitution(s) 1 Arecibo ObservatoryUSRA 2 CornellUniversity 3 JHUAPL 4 LPLU Arizona 5 U Central Florida6 U Maine at Farmington

21312 ndash Spectrophotometric Properties of GasprarsquosSurfaceUsing the shape-model derived for Gaspra [1] we calculate the localincidence emission and phase angles on a pixel-by-pixel basis forthe color image sets (164 mpx spatial resolution) acquired by theGalileo Solid State Imager (SSI) [2] Using these geometric valueswe derive a disk-resolved photometric correction for application tothe to the spectral data set for more accurate regional examinationof mineralogy and weathering across the surface We use regionalvariations in color ratios of Gasprarsquos surface to examine the degreeof space weathering incurred upon the surface and find subtlevariations across its surface Using mixing modeling methods thataccount for submicroscopic components we examine evidence forspace weathering variations correlated to composition and grainsize We note evidence of a young surface with only moderatemodification by space weathering processes SSI radiometrically-calibrated data combined with shape-model derived incidenceemission and phase angle backplanes have been archived in thePlanetary Data System for broader use by the community [3 4][1] P Thomas et al 1994 Icarus 107 23 ndash 36 [2] M Belton et al1992 Science 257 1647 ndash 1652 [3] D Domingue 2015 GalileoSSIGaspra Radiometrically Calibrated Images V10 NASA PDS[4] D Domingue 2015 Galileo SSIGaspra Color and GeometryImage Cubes V10 NASA PDS submitted

Author(s) Deborah L Domingue Faith Vilas KarenStockstill-Cahill Joshua Cahill Amanda HendrixInstitution(s) 1 Johns Hopkins UniversityApplied PhysicsLaboratory 2 Planetary Science Institute

21313 ndash Methodology of Space Weathering Simulationand Its Application on Olivine and Pyroxene SamplesHere we reported a two-step thermal treatment method [1] for thespace weathering simulation and the differences in the formationof metallic iron nanoparticles (npFe ) on the surface of olivine andpyroxene samples are discussedIn general the main goal is in controlled size of npFe formed onthe surface of olivine and pyroxene and in quantification of therelated spectral changes The transmission electron microscopy(TEM) after double-heating method revealed two significantfeatures First different sizes and concentration of npFe areobserved and secondly due to more resistance of pyroxene (eg[2]) higher temperatures are needed to produce the same amountof npFe as in the olivine case [1]Results from TEM are fully consistent with reflectance spectrawhich show progressive changes as a function of the increasingnpFe amount The reason for the observed differences inreflectance spectra can be found in the crystal structure and localenvironment at each crystallographic position of both samples It isvery similar as in the case of laser heating experiments (eg [2])where the surface of orthopyroxene is significantly more resistantto reduction than olivine due to mobility of oxygen and cationdiffusions from the bulk to surface of the samplesReferences[1] Kohout T et al (2014) Icarus 237 75-83[2] Quadery A et al (2015) JGR-Planets 120 1-19

Author(s) Ondrej Malina Tomas Kohout Jiri Tucek JanFilip Daniel Britt Radek ZborilInstitution(s) 1 Department of Physics University of CentralFlorida 2 Palacky University 3 University of HelsinkyDepartment of Physics

21314 ndash Visible Wavelength Reflectance Spectra andTaxonomies of Near-Earth Objects from Apache PointObservatoryNear-Earth Objects (NEOs) are interesting to scientists and the

1

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1 2 5

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0

0

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general public for diverse reasons their impacts pose a threat to lifeand property they present important albeit biased records of theformation and evolution of the Solar System and their materialsmay provide in situ resources for future space exploration andhabitationIn January 2015 we began a program of NEO astrometric follow-upand physical characterization using a 17 share of time on theAstrophysical Research Consortium (ARC) 35-meter telescope atApache Point Observatory (APO) Our 500 hours of annualobserving time are split into frequent short astrometric runs (seeposter by K A Nault et al) and half-night runs devoted to physicalcharacterization (see poster by M J Brucker et al for preliminaryrotational lightcurve results) NEO surface compositions areinvestigated with 036-10 μm reflectance spectroscopy using theDual Imaging Spectrograph (DIS) instrument As of August 252015 including testing runs during fourth quarter 2014 we haveobtained reflectance spectra of 68 unique NEOs ranging indiameter from approximately 5m to 8kmIn addition to investigating the compositions of individual NEOs toinform impact hazard and space resource evaluations we mayexamine the distribution of taxonomic types and potential trendswith other physical and orbital properties For example theYarkovsky effect which is dependent on asteroid shape massrotation and thermal characteristics is believed to dominate otherdynamical effects in driving the delivery of small NEOs from themain asteroid belt Studies of the taxonomic distribution of a largesample of NEOs of a wide range of sizes will test this hypothesisWe present a preliminary analysis of the reflectance spectraobtained in our survey to date including taxonomic classificationsand potential trends with sizeAcknowledgements Based on observations obtained with theApache Point Observatory 35-meter telescope which is owned andoperated by the Astrophysical Research Consortium We gratefullyacknowledge support from NASA NEOO award NNX14AL17G andthank the University of Chicago Department of Astronomy andAstrophysics for observing time in 2014

Author(s) Mark Hammergren Melissa J Brucker KristieA Nault Geza Gyuk Michael R SolontoiInstitution(s) 1 Adler Planetarium 2 Lynchburg College

21315 ndash A 3 mircon spectral survey of Jupiter trojansThe surface compositions of Jupiter trojans remain mysteriousWhile the red colors have often been taken to be indicative of thepresence of organic materials no distinct spectral features havebeen found in reflectance spectroscopy spanning 04 - 25 micronswhile thermal emission spectroscopy has shown only the signatureof fine-grained silicates Many materials which may reside on thesurfaces of Jupiter trojans have their strongest fundamental bandsin the 3-4 micron region making this spectral region a prime targetfor understanding composition of otherwise featureless objectsWe have obtained 2-4 micron spectra of 16 large Jupiter trojansusing the NIRSPEC instrument at the Keck Observatory We findsignificant variability in the spectral behavior across this rangeWhile some of the Jupiter trojan asteroids remain featurelessothers have a deep absorption at 3 microns The depth of this 3micron absorption feature is strongly correlated with the opticalcolor of the individual asteroid We will discuss possible spectralidentifications of this spectral feature the implications of the color-absorption correlation and conclusions to be drawn on the sourceof the Jupiter trojans

Author(s) Michael E BrownInstitution(s) 1 Caltech

21316 ndash A Near-Infrared Spectral Survey of HungariaRegion Asteroids Compositionally Diverse Neighborsof the Terrestrial PlanetsThe surface compositions of Hungaria region asteroids are poorlyunderstood These neighbors to the terrestrial planets are uniqueas they are found interior to the Main-belt and have resided in theircurrent location since early in solar system history Mars-crossingand near-Earth asteroids make closer approaches to the terrestrialplanets but they are dynamically short-lived (~10 Myr) escapees

from the Main-belt Original planetesimals within the terrestrialplanet region were either accreted or scattered out early in solarsystem history leaving the Hungarias as the closest remainingldquosurvivorsrdquo of the asteroidal material from which the terrestrialplanets accretedWe have undertaken an observational campaign to record thenear-infrared reflectance spectra of 42 (36 background 6 family)Hungaria asteroids with absolute magnitudes H lt16 tocharacterize their surface mineralogy through spectral bandparameter measurements By comparing these telescopic data withspectral and geochemical data obtained in the laboratory fromldquofreerdquo asteroid samples that arrive to Earth as meteorites we canestablish connections between Hungaria asteroids and analogousmeteorite groupsWe find evidence of three main meteorite-groups represented inthe Hungaria region 1) enstatite achondrites (ie aubrites) 2)ordinary chondrites (ie H L and LL) and 3) primitiveachondrites (ie acapulcoites and lodranites) Five of the sixHungaria family members are spectrally consistent with the largestcollisional fragment (434) Hungaria which is widely considered tobe related to fully-melted aubrite meteorites Analyses of spectralband centers and band area ratios for 25 of 36 Hungariabackground objects reveal evidence for two other meteorite groupsPublished laboratory data for ordinary chondrites compared withour asteroid spectra point to the existence of unmelted L and LLchondrites in the region Preliminary results from the laboratoryanalyses of our suite of 12 primitive achondrites indicate theexistence of partially-melted primitive achondrites in the region aswell These asteroid-meteorite connections suggest thatplanetesimals in the Hungaria region have experienced varyingdegrees of petrologic evolution

Author(s) Michael P Lucas Joshua P Emery NoemiPinilla-Alonso Sean S Lindsay Vania LorenziInstitution(s) 1 Department of Earth amp Planetary SciencesUniversity of Tennessee 2 Department of Physics amp AstronomyUniversity of Tennessee 3 Fundacioacuten Galileo Galilei - IstitutoNazionale di Astrofisica

21317 ndash Error Analysis of Stereophotoclinometry inSupport of the OSIRIS-REx MissionStereophotoclinometry has been used on numerous planetarybodies to derive the shape model most recently 67P-Churyumov-Gerasimenko (Jorda et al 2014) the Earth (Palmer et al 2014)and Vesta (Gaskell 2012) SPC is planned to create the ultra-highresolution topography for the upcoming mission OSIRIS-REx thatwill sample the asteroid Bennu arriving in 2018 This shape modelwill be used both for scientific analysis as well as operationalnavigation to include providing the topography that will ensure asafe collection of the surfaceWe present the initial results of error analysis of SPC with specificfocus on how both systematic and non-systematic error propagatethrough SPC into the shape model For this testing we havecreated a notional global truth model at 5cm and a single region at25mm ground sample distance These truth models were used tocreate images using GSFCs software Freespace Then these imageswere used by SPC to form a derived shape model with a groundsample distance of 5cmWe will report on both the absolute and relative error that thederived shape model has compared to the original truth model aswell as other empirical and theoretical measurement of errorswithin SPCJorda L et al (2014) The Shape of Comet 67PChuryumov-Gerasimenko from RosettaOsiris Images AGU Fall MeetingP41C-3943 Gaskell R (2012) SPC Shape and Topography ofVesta from DAWN Imaging Data DSP Meeting 44 20903Palmer L Sykes M V Gaskll RW (2014) Mercator mdashAutonomous Navigation Using Panoramas LPCS 45 1777

Author(s) Eric Palmer Robert W Gaskell John R WeirichInstitution(s) 1 Planetary Science Institute

21318 ndash From microscope to telescope Usinglaboratory spectroscopic measurements to constrain

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the thermal evolution of silicate bodies in the solarsystemSpectral measurements of planets and asteroids have long beenused to inventory the composition of their surfaces If laboratorytechniques can be extrapolated to the larger spatial scales of remoteobservations infrared spectroscopic measurements offer thepotential to delve even deeper into the thermal evolution of thesebodies However the scattering of light and mixing from themicroscopic through macroscopic scales greatly complicates theanalysis of components present even when surfaces are viewed atcomparably high spatial resolution (lt10-100 mpixel) For thisproject we have prepared and measured a set of meteorites andterrestrial analog rocks to perform coordinated spectroscopicstudies from microscopic spectral measurements across individualgrains through measurement of bulk mineral and rock samples inultra-high vacuum (UHV) to investigate two questions (1) canmicroscopic mineral textures related to cation ordering andexsolution be reliably distinguished from physical mixtures asoccur in regoliths and (2) can internally bound water in minerals bedistinguished from water that has adsorbed from the environmentIn each case we explore how well the laboratory techniquesaddress these questions and through spectral modeling what thelimitations and challenges are for extrapolating thesemeasurements to remote observations

Author(s) Rachel L Klima Brianna C Young Andy SRivkinInstitution(s) 1 Johns Hopkins University Applied PhysicsLaboratory

21319 ndash New insights into asteroid 3200 Phaethonsmeteor complexIn this work we study the meteor complex originating fromasteroid 3200 Phaethon Using a modeling of variety of meteoroidstreams and following their dynamical evolution we confirm thepresence of two filaments crossing the Earth observed as Geminidand Daytime Sextantid meteor showers We use numericalintegrations of modeled particles performed for several pastperihelion passages of the asteroid considering (i) only the gravityof planets and (2) gravity of planets and the Poynting-Robertsoneffect We present the results of comparing our models (predictedshowers) with observed showers We also point out discrepanciestheir possible solutions andor new hypothesis concerning theexamined meteor complex

Author(s) Marian Jakubik Lubos NeslusanInstitution(s) 1 Astronomical Institute of the Slovak Academyof Sciences

21320 ndash Scale-Dependent Measurements of MeteoriteStrength and Fragmentation Tamdakht (H5) andAllende (CV3)Meteorites are pieces of natural space debris which have survivedejection from their parent bodies and passage through the Earthrsquosatmosphere As such they provide a unique opportunity to studythe fundamental physical and mechanical properties of early SolarSystem materials But to date few direct studies of physicalproperties have been conducted on meteoritic materials in contrastto extensive chemical and isotopic analyses It is important todetermine these properties as they are related to disruption andfragmentation of bolides and asteroids and activities related tosample return and hazardous asteroid mitigation Here we presentresults from an ongoing suite of scale-dependent studies ofmeteorite strength and fragmentation The meteorites studied areTamdakht (H5) an ordinary chondrite that exhibits aheterogeneous structure criss-crossed with shock veins andcentimeter-sized regions of white and light grey and thecarbonaceous chondrite Allende (CV3) which suitable pieces arelight grey with abundant chondrules and CAIs Uniaxialcompression tests are performed on meteorite cubes ranging from05 to 4 centimeters using an Instron 5985 frame with a 250 kNload cell and compression fixtures with 145mm diameter radialplatens All tests are conducted at room temperature and indisplacement control with a displacement rate of 025 mm per

minute to ensure quasi-static conditions A three-dimensionaldigital image correlation (DIC) system that enables noncontactmeasurement of displacement and strain fields is also usedAnalysis of the strength and failure process of the two meteoritetypes is conducted and compared to terrestrial materials

Author(s) Desireeacute Cotto-Figueroa Erik Asphaug LaurenceGarvie Melissa Morris Ashwin Rai Aditi Chattopadhyay Nikhilesh ChawlaInstitution(s) 1 Arizona State University 2 State University ofNew York at Cortland

21321 ndash Compositional study of asteroids in theErigone collisional family using visible spectroscopyat the 104m GTCAsteroid families are formed by the fragments produced by thedisruption of a common parent body (Bendjoya amp Zappalagrave 2002)Primitive asteroids in the solar system are believed to haveundergone less thermal processing than the S-complex asteroidsThus study of primitive asteroid families provides informationabout the solar system formation period The Erigone collisionalfamily together with other three families (Polana Clarissa andSulamitis) are believed to be the origin of the two primitiveNear-Earth asteroids that are the main targets of the NASArsquosOSIRIS-REx ((101955) Bennu) and JAXArsquos Hayabusa 2 ((162173)1999 JU3) missions (Campins et al 2010 Campins et al 2013Lauretta et al 2010 Tsuda et al 2013) These spacecrafts will visitthe asteroids and a sample of their surface material will bereturned to Earth Understanding of the families that areconsidered potential sources will enhance the scientific return ofthe missions The main goal of the work presented here is tocharacterize the Erigone collisional family Asteroid (163) Erigonehas been classified as a primitive object (Bus 1999 Bus amp Binzel2002) and we expect the members of this family to be consistentwith the spectral type of the parent body We have obtained visiblespectra (05-09 μm) for 101 members of the Erigone family usingthe OSIRIS instrument at the 104m Gran Telescopio Canarias Weperformed a taxonomical classification of these asteroids findingthat the number of primitive objects in our sample is in agreementwith the hypothesis of a common parent body In addition we havefound a significant fraction of asteroids in our sample that presentevidences of aqueous alteration Study of aqueous alterations isimportant as it can give information on the heating processes ofthe early Solar System and for the associated astrobiologicalimplications (it has been suggested that the Earthrsquos present watersupply was brought here by asteroids instead of comets inopposition to previous explanations (Morbidelli et al 2000)

Author(s) David Morate Julia de Leoacuten Maacuterio De Praacute Javier Licandro Antonio Cabrera-Lavers Humberto Campins Noemiacute Pinilla-Alonso Viacutector Aliacute-LagoaInstitution(s) 1 GTC Project Office 2 Instituto de Astrofisica deCanarias 3 Lagrange Boulevard de lrsquoObservatoire 4Observatoacuterio Nacional 5 University of Central Florida 6University of Tennessee

214 ndash Asteroid Dynamics21401 ndash On the dynamical dispersal of primordialasteroid familiesMany asteroid families are identified and well characterized all overthe main belt asteroid Interestingly however none of them areolder than ~4 Gyr Many mechanisms have been proposed todisperse such old primordial asteroid families that presumablyhave existed but none have really worked Here we present aplausible mechanism for dispersing primordial asteroid familiesthat is based on the 5-planet instability model known as jumpingJupiter Using two different evolutions for the jumping-Jupitermodel we have numerically integrated orbits of eight primordialfamilies Our results show that the most important effect on theasteroid families eccentricity and inclination dispersal is that of thesecular resonances in some cases associated with the mean motionresonances As for the semimajoraxes spreading we find that the

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principal effect is that of close encounters with the fifth giant planetwhose orbit briefly overlaps with (part of) the main belt Thereforethe existence of a fifth giant planet with the mass comparable withthat of Uranus or Neptunes could contribute in important ways todispersal of the primordial asteroid families To have that effect theinterloper planet should penetrate and considerably interact withthe asteroids during the instability phase

Author(s) Pedro Ivo de Oliveira Brasil Fernando Roig David Nesvornyacute Valerio Carruba Safwan Aljbaae MarielaEspinoza HaumanInstitution(s) 1 Observatoacuterio Nacional 2 SwRI 3 UNESP

21402 ndash Modeling Asteroid Dynamics using AMUSEFirst Test CasesWe are creating a dynamic model of the current asteroidpopulation The goal is to reproduce measured impact rates in thecurrent Solar System from which well derive delivery rates ofwater and organic material by tracing low-albedo C-class asteroids(using the measured albedo distribution from WISE catalog) theparent bodies of carbonaceous chondrite meteorites Ultimatelywe aim at studying the role of exo-asteroids in the delivery ofwater to exoplanetsOur model is set up using the Astrophysical Multipurpose SoftwareEnvironment (AMUSE amusecodeorg) AMUSE provides acommon Python wrapper around numerous astrophysical codesincluding N-body gravity codes such as Mercury and HuaynoWe report first results towards a validation of our model long-termintegrations of the planets alone as well as studies of the depletionof the Kirkwood gaps in the asteroid belt Further modeldevelopments will be discussed

Author(s) Kateryna Frantseva Michael Mueller Floris vander Tak Frank P HelmichInstitution(s) 1 Kapteyn Astronomical Institute (University ofGroningen) 2 Netherlands Institute for Space Research

21403 ndash Stability of the Slivan statesThe past decade has seen an increase in the number of asteroids forwhich observations allowed resolving the rotation pole orientationThis data led to new studies of asteroids and their populations Oneof the early examples was a discovery of Slivan states in the Koronisfamily (Slivan 2002) The group of prograde-rotating asteroids hadspin axes nearly parallel in inertial space and similar rotationperiods (later dubbed the Slivan states) Vokrouhlicky et al (2003)proposed model based on the idea that the spin axis is confined in aresonance between its precession rate by solar torques and aparticular mode of these asteroidsrsquo orbit precession in the inertialspace (in this case the s mode) The theoretical frameworkdescribing such situation is called Cassini dynamicsSince the past decade the importance of the Cassini dynamics indescription of asteroid rotation has significantly increased we aimto present an efficient tool for its descriptionWe combined two symplectic integration tools into a singlesoftware First we use the widespread and well-tested swiftintegrator for orbital dynamics of the asteroid (Levison amp Duncan1994) Second we included the spin propagator formulated byBreiter et al (2005) into the swift architecture This enables tosimultaneously integrate orbital and rotational dynamics in a singlerunWe show tests that reproduce Slivan states in the Koronis zone Wealso analyse stability of the Slivan states in the inner main beltspecifically in the Flora family region We find Massalia family to bea more suitable inner main-belt location of the classical Slivanstates because of a separation between the s and s nodalfrequencies We also demonstrate that the Slivan states mayassociated with other than the s frequency Under well-tunedconditions the Slivan states may also exists for the s planetaryfrequency For the outer main-belt body 184 Dejopeja we find itspole location near a stable s -associated Slivan state Because theforced inclination of the s term is significantly smaller than that ofthe s term the obliquity range of the s Cassini state is very smallTherefore the new s -related Slivan states are perhaps of only anacademic interest

Author(s) Jan Vrastil David VokrouhlickyInstitution(s) 1 Charles University in Prague

21404 ndash The Orbit and Size of (87) Sylvias Romulusfrom the 2015 ApparitionUsing the US Air Forces Starfire Optical Range 35 meter telescopewith adaptive optics and a laser guidestar we obtained 68 images ofasteroid (87) Sylvia and its satellite Romulus over 10 nights inMarch and May of 2015 Adding an additional 3 images from earlierobservations on one night in November 2012 we are able to derivea circular (but not an eccentric) orbit for Romulus leading to adensity for Sylvia of 137plusmn004 gmcm Extending the time base to14 years by combining our data with previous observations fromKeck HST and the VLT reported in the literature we can fit for anew circular orbit and improve the density estimate to 135plusmn003gmcm By fitting a Fourier series to the measured magnitudedifference between Sylvia (V=125) and Romulus which rangedfrom 41 to 51 in the J-band (λ=12microm) and modeling both astriaxial ellipsoids we are able to derive equatorial ellipsoiddiameters for Romulus of 39x29 both plusmn1 km (All errors here areformal fitting errors) As far as we know our 35 m telescope is thesmallest ground-based telescope to ever image any asteroidsmoon

Author(s) Jack D Drummond Odell Reynolds MilesBuckmanInstitution(s) 1 Starfire Optical Range

21405 ndash The evolution of asteroids in the jumping-Jupiter migration modelIn this work we investigate the evolution of a primordial belt ofasteroids represented by a large number of massless test particlesunder the gravitational effect of migrating Jovian planets in theframework of the jumping-Jupiter model We perform severalsimulations considering test particles distributed in the Main Beltas well as in the Hilda and Trojan groups The simulations startwith Jupiter and Saturn locked in the mutual 32 mean motionresonance plus 3 Neptune-mass planets in a compact orbitalconfiguration Mutual planetary interactions during migration ledone of the Neptunes to be ejected in less than 10 Myr of evolutioncausing Jupiter to jump by about 03 au in semi-major axis Thisintroduces a large scale instability in the studied populations ofsmall bodies After the migration phase the simulations areextended over 4 Gyr and we compare the final orbital structure ofthe simulated test particles to the current Main Belt of asteroidswith absolute magnitude H lt 97 The results indicate that in orderto reproduce the present Main Belt the primordial belt should havehad a distribution peaked at sim10 in inclination and at sim01 ineccentricity We discuss the implications of this for the Grand Tackmodel The results also indicate that neither primordial Hildas norTrojans survive the instability confirming the idea that suchpopulations must have been implanted from other sources Inparticular we address the possibility of implantation of Hildas andTrojans from the Main Belt population but find that thiscontribution should be minor

Author(s) Fernando Virgilio Roig David NesvornyacuteInstitution(s) 1 Observatorio Nacional 2 Southwest ResearchInstitute

21406 ndash Predicting close encounters betweenasteroids with the STB softwareWe have developed a method that can quickly and efficientlycalculate close encounters between all known asteroids both in thepast and the future Only several hundred asteroids out of morethan 690000 have their masses currently known The mostaccurate values are from direct measurements by in situ visits (egDawn at Ceres and Vesta (Russell et al 2012 Science 336 6082pp 684) Hayabusa at Itokawa (Abe et al 2006 Science 312 5778pp 1344-1349)) followed by measurements of binary systems andalso from mutual orbit perturbations during close encountersbetween a handful of the largest MBAsWe used software called ldquoSpace Time Boxrdquo (STB) invented by IBMcapable of efficiently determine co-located entities in 3D space and

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time Orbits from the MPCORBDAT database were placed intoselected STB granularity with 1 day and 005 AU-wide bins Bydetermining and only tracking asteroids co-located within aselected minimal distance the computational requirements weresignificantly reduced Selected instances of co-location were thenprovided as an input for a numerical integrator SWIFT with 8planets as perturbers and were integrated until desired epoch witha 05 and 1 day timestep We then used interpolation for thespecified time window to check if the positions of asteroidsintersect or are within a certain distance parameterUsing the STB optimization we calculated close encountersbetween years 2014 and 2039 These events offer the opportunityto search in the survey archives for potential collisions andcarefully select the events for mass determination based on theirminimal approach distance angle and mass ratio of participatingobjects A follow-up astrometric campaign would ensureimprovement of the mass determination precision Predictedfuture events can also be directly observed in the real time withoptical and IR telescopes in search for collisions or mass lossAs an example we present one close encounter event observed withthe University of Hawaii 22 m telescope on June 9th 2015

Author(s) Eva Lilly (Schunova) Jeff Jonas MudhakarSrivatsa Raghu Ganti Dakshi Agrawal Larry Denneau Martin Kratky Richard J WainscoatInstitution(s) 1 Comenius University Bratislava 2 IBM 3Institute for Astronomy University of Hawaii

21407 ndash Thermally-driven destruction of asteroids atsmall perihelion distancesState-of-the-art models describing the orbits and absolutemagnitudes of near-Earth objects (NEOs) predict that numerousNEOs should have been found on orbits with small periheliondistances but few actual discoveries have been made In additioneven though the NEO population in general is an even mix oflow-albedo and high-albedo asteroids the characterized NEOs nearthe Sun show a strong preference for high albedos We have foundvia a quantitative comparison of actual NEO detections and a newNEO model accounting for observational selection effects that thedeficit is produced by the super-catastrophic disruption of asubstantial fraction of NEOs when they achieve periheliondistances of a few tens of solar radii The destruction distanceincreases for small asteroids and their temperatures duringperihelion passages do not reach levels where evaporation couldexplain their disappearance Although both bright and darkasteroids eventually disrupt our work shows a preference for theelimination of low-albedo NEOs farther from the Sun whichexplains the apparent excess of high-albedo NEOs and suggeststhat low-albedo asteroids break more easily as a result of thermaleffects

Author(s) Mikael Granvik Alessandro Morbidelli RobertJedicke Bryce Bolin William F Bottke Ed Beshore DavidVokrouhlicky Marco Delbo Patrick MichelInstitution(s) 1 Institute for Astronomy University of Hawaii2 Institute of Astronomy Charles University 3 OCA 4Southwest Research Institute 5 University of Arizona 6University of Helsinki

21408 ndash Monitoring NEO discoveries for imminentimpactorsWe are setting up an automated service that will regularly computeasteroid-Earth collision probabilities for objects on the MinorPlanet Centers Near-Earth-Object Confirmation Page (NEOCP)Our goal is to identify objects similar to 2008 TC and 2014 AA andprovide enough warning time to allow for eg detailed follow-upobservations prior to a collision Our system downloads all the newdata on the NEOCP every 30 minutes and for each object with newdata solves the orbital inverse problem which results in a sample oforbits that describes the typically highly-nonlinear orbital-elementprobability-density function (PDF) We then propagate the orbital-element PDF forward in time for 7 days and compute the collisionprobability as the weighted fraction of the sample orbits that impactthe Earth Our tests have shown that the system correctly predicts

the collisions of 2008 TC and 2014 AA based on the very firstastrometry batches available (collision probabilities greater than70) Using the same configuration we find that the collisionprobabilities for objects typically on the NEOCP based on 4 weeksof continuous operations are always less than 1 in 10 million

Author(s) Otto Solin Mikael Granvik Karri MuinonenInstitution(s) 1 University of Helsinki

21409 ndash Overview of the JPL Center for NEO Studies(CNEOS)Concurrent with the reformulation of NASArsquos Near-Earth Object(NEO) program at NASA Headquarters the Jet PropulsionLaboratory has formed the Center for NEO Studies (CNEOS)which will continue the technical work on NEOs that JPL hasperformed in the past and expand on that work The poster willprovide a brief history of NEO activities at JPL including theestablishment of the original NEO Program Office at JPL in 1998 toprovide a central node of critical expertise in the area of trajectorydynamics of Near-Earth Objects (NEOs) With the reformulation ofthe NEO program at NASA HQ that office has become the Centerfor NEO Studies The poster will review some of the Centerrsquos keyactivities such as the computation of high precision orbits forNEOs tabulation of their close approaches and calculation ofimpact probabilities by all known NEOs over the next century viathe Sentry and Scout impact monitoring systems The Center willcontinue to host the website for NASArsquos NEO Program providingdetailed information on the orbits and physical characteristics of allknown NEOs Other technical activities of the Center will also beoutlined including the Horizons on-line ephemeris service thedevelopment of hypothetical impact scenarios and online kinetic-impactor deflection analysis tools and the detection and mappingof keyholes

Author(s) Paul ChodasInstitution(s) 1 Jet Propulsion Laboratory

21410 ndash Gravitational Influence of a Large CapturedBody on the Stability of Jupiterrsquos Trojan AsteroidsThe Trojan asteroids orbit the Sun about the L4 and L5 Lagrangianpoints of Jupiter These objects have a wide range of eccentricitiesand inclinations and are thought to be captured planetesimalsSince the origin of the Trojan asteroids is expected to provide cluesto the dynamical evolution of the planets and small bodies in theSolar System various models have been proposed eg capturedue to gas drag from the solar nebula capture during Jupiterrsquosmass growth or capture during smooth migration of JupiterHowever such models failed to reproduce some importantcharacteristics of the present Trojan asteroids such as the totalmass of the Trojans the distribution of orbital elements or thedistribution of the libration amplitudes On the other hand recentmodels for the formation of the Solar System suggest that the giantplanets likely experienced significant radial migration and orbitalinstability after their formation Studies of capture of Trojanasteroids based on such models of giant planet migration show thaticy planetesimals originally in the outer Solar System can becaptured into Jupiterrsquos Trojan regions and the present total massas well as the observed orbital characteristics of the Trojanasteroids can be explained in such models However in suchstudies of capture of the Trojan asteroids asteroids were treated astest particles thus gravitational interactions between planetesimalsare not taken into account Although effects of gravitationalinteractions between sufficiently small asteroids may reasonably beneglected there may have been significantly large objects in theoriginal swam of Trojan asteroids immediately after their captureIn the present study we assume that a large body was captured intoJupiterrsquos Trojan region and examine its dynamical influence onother Trojan asteroids using orbital integration From the results ofour calculations we will discuss constraints on the mass of bodiesexisted in the Trojan swarm in the past

Author(s) Keiji Ohtsuki Hiroaki OkayamaInstitution(s) 1 Kobe University

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215 ndash Mercury and the Moon21501 ndash Observations of the minor species Al Fe andCa in Mercuryrsquos exosphereWe report here on the first observational evidence of Al and Fe inthe exosphere of Mercury based on measurements of 4-5-σresolved emission lines of these metals with Keck-1HIRES AlIemission was observed on two separate runs in 2008 and 2013with tangent column densities of 24 and 3 x 10 Al atoms cm ataltitudes of 1300 and 1850 km (11 and 15 R ) respectively FeIemission has been observed once yielding a tangent column of 62x 10 cm at an altitude of 950 km (14 R ) in 2009 We alsopresent observations of 35-σ Ca emission features nearMercuryrsquos equatorial anti-solar limb in 2011 from which astringent tangent column abundance of 40 x 10 cm is derivedfor the Ca ionA simple model for zenith column abundances of the neutralspecies yields 20 x 10 Al cm and 82 x 10 Fe cm Theobservations appear to be consistent with production of thesespecies by impact vaporization with a large fraction of the Al ejectain molecular form and that for Fe in mixed atomic and molecularforms The scale height of the Al gas is consistent with a kinetictemperature of 4800-8200 K while that of Fe is 5000-13000 KThe apparent high temperature and low density of the Al gas wouldsuggest that it may be produced by dissociation of molecules Alarge fraction of both Al and Fe appear to condense in a vapor cloudat low altitudes

Author(s) Rosemary M Killen Thomas A BidaInstitution(s) 1 Lowell Observatory 2 NASA Goddard SpaceFlight Center

21502 ndash Dissociation of Ca-bearing Molecules as aSource of Mercurys Ca ExosphereObservations of Mercurys calcium exosphere by MESSENGERhave revealed three key features (1) The Ca is extremely energeticwith a temperature ~70000 K if the source is thermal (2) thesource region is located in the dawn hemisphere and (3) there is astrong annual variation in the Ca source rate (Burger et al 2014)Killen and Hahn (2015) have shown that the source rate isconsistent with impact vaporization by interplanetary dust and theintersection of Mercury with a cometary dust stream (likelyassociated with Comet Encke Christou et al submitted)Killen et al (2005) suggested that energetic calcium could beproduced by the dissociation of Ca-bearing molecules produced inimpact vaporization plumes We test this hypothesis with a MonteCarlo model that follows the evolution of atomic and molecularcalcium produced in impact plumes Ca-bearing molecules such asCaO CaOH and Ca(OH) are more likely to be are produced invapor plumes than atomic Ca (Berezhnoy and Klumov 2008)these molecules quickly break apart either through vibrationaldissociation or photodissociation The excess energy associatedwith dissociation gives the atomic Ca an extra energy boost abovethe temperature of the impact plumes (~5000 K) We determineimpact vaporization rates and excess energies required by thedissociation process to reproduce the scale height and spatialmorphology of the Ca exosphere as observed by the MESSENGERUltraviolet and Visible Spectrometer (UVVS)ReferencesBerezhnoy AA and Klumov BA Impacts as sources of theexosphere on Mercury Icarus 195 511-522 2008doi101016jicarus200801005Burger MH et al Seasonal variations in Mercurys daysidecalcium exosphere Icarus 238 51-58 2014doi101016jicarus201404049Killen RM et al The calcium exosphere of Mercury Icarus 173300-311 2005 doi101016jicarus200408022Killen RM and Hahn JM Impact vaporization as a possiblesource ofMercurys calcium exosphere Icarus 250 230-237 2015doi101016jicarus201411035

Author(s) Matthew H Burger Rosemary M KillenInstitution(s) 1 GSFC 2 Morgan State University

21503 ndash Comparing Different Exospheric Species atMercury to Constrain Source Loss and TransportProcessesMercuryrsquos exosphere is maintained by processes that eject atoms ormolecules from the surface of the planet The atoms are initially apart of the regolith or are possibly delivered to the planet viameteorites In either case spatial and temporal variations in sourceprocesses dynamical transport processes such as radiationpressure and ion recycling and the surface chemistry associatedwith exospheric atoms impacting the regolith affect the distributionof species in the exosphere Each of these processes acts differentlydepending on the particular atom due in part to the atomic masssurface sticking coefficient and thermal accommodationcoefficient of the atom A comparison between the differences andsimilarities in the spatial distribution and temporal variations ofmore than one atomic species helps to unravel the physicalprocesses driving the exosphere and ultimately helps to understandsurface-exosphere interactions The Mercury Atmospheric andSurface Composition Spectrometer (MASCS) on the MESSENGERspacecraft obtained profiles of Mercuryrsquos exosphere during threeMercury flybys and during the orbital phase of the mission fromMarch 2011 through April 2015 Specifically MASCS a scanning-grating monochromator observed resonantly scattered emissionsat discrete wavelengths from atoms in the exosphere A strategywas employed where several exospheric species were observedsequentially with integration times short enough that theobservations for a particular set of exospheric atoms were almostsimultaneous These measurements are useful for comparing thedistributions of different atoms since the geometry associated withthe observation of each species is approximately the same I willpresent results from an analysis of MASCS data comparing thedifferences and similarities of the spatial distributions andtemporal variations of different exospheric species

Author(s) Eric Todd BradleyInstitution(s) 1 Univ of Central Florida

21505 ndash Characterizing Water and Hydroxyl onAirless Bodies from Vacuum UV and IR MeasurementsWater exists in the surfaces of airless bodies as ice and potentiallyas adsorbed species [1] either as molecular water or dissociatedinto hydroxyl when bulk water (ice) is not stable [2] All physicalstates of water have a strong spectral signatures in the infraredfrom 27 to 3-um because of a fundamental OH-cation or H-O-Hstretch vibration But the IR is not always definitive of physicalstate Although a band at 307 um is associated with water ice analmost identical band exists in some hydrated minerals Brucite analteration product of olivine possesses this band [6] as doesgoethite another alteration mineral of basalts [7] In fact the305-um band on Ceres which was initially attributed to water icehas more recently been attributed to brucite [6] Spectralobservations in the UV can potentially resolve this degeneracy Inthe UV water ice possesses a very strong band near 180 nm [8]but adsorbed molecular water does not induce a band Because ofthis a combination of UV measurements at wavelengths from ~150 nm to ~200 nm and IR measurements near 3 um candiscriminate ice from adsorbed water The UV region however isalso sensitive to silicate composition with iron bearing mineralshaving a strong OMCT absorption feature near 300 nm and againshortward of 200 nm that can potentially be a source of confusionbetween the identification of iron-poor minerals and water ice Inconclusion the IR can sense all three forms of water (ice adsorbedmolecular water and hydroxyl) and the UV being sensitive to icemay potentially be used either alone or with the IR to identify waterice separately from other phases of hydrationReferences [1] Hibbitts et al Icarus 213 64-72 2011 [2]Schorghofer N and GJ Taylor JGR 112 E02010doi1010292007 [3] Poston et al JGR 118 105-115 2013 [4] Dyar et alIcarus 208425-437 2010 [5] Zeller et al JGR 71 4855-48601966[6] Milliken RE and AS Rivkin Nature Geosci DOI101038 2009 [7] Beck P et al 42 LPSC 2047 2011 [8]Hendrix AR and CJ Hansen Icarus 193 323-333 2008

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Author(s) Charles A HibbittsInstitution(s) 1 JHU-APL

21506 ndash Revised Age Constraints on Absolute AgeLimits for Mercurys Kuiperian and MansurianSystemsOn the basis of morphologically distinct basin and crater depositsMercuryrsquos surface units have been subdivided into fivetime-stratigraphic systems (youngest to oldest) KuiperianMansurian Calorian Tolstojan and pre-Tolstojan Approximateage limits were initially suggested for these systems on the basis ofthe lunar-derived impact-flux history High-resolution andmulti-band image data obtained by the MErcury Surface SpaceENviroment GEochemistry and Ranging (MESSENGER)spacecraft were used to catalogue fresh impact craters interpretedto have formed during the Mansurian and Kuiperian systemsMansurian and Kuiperian craters are characterized asmorphologically fresh with crisp morphologies well-preservedrims few or no superposed craters continuous ejecta with radiallineaments and well-defined secondary craters Kuiperian cratershave bright ray systems while Mansurian craters maintain freshmorphologies but no longer have discernable ray systemsThe density of fresh craters in these datasets along with the recentproduction and chronology function of Marchi et al [2009] areused to estimate new limits for the boundaries of the two mostrecent of Mercuryrsquos systems Given the effects of strength andother parameters (such as density) we estimate a model age for thepopulation of craters that have formed since the onset of theMansurian of ~19 plusmn03 Gyr Likewise we estimate a model age forthe population of craters that have formed since the onset of theKuiperian of ~300 plusmn40 Myr A particularly good fit for theMansurian crater size frequency distribution (SFD) was found forthe NEO-derived crater distribution The same is true for theKuiperian SFD although the fit is not as robust as for theMansurian SFD

Author(s) Maria E Banks Xiao Zhiyong Sarah E Braden Simone S Marchi Nadine G Barlow Clark R Chapman CalebI FassettInstitution(s) 1 Arizona State University 2 Department ofSpace Studies Southwest Research Institute 3 Dept ofAstronomy Mount Holyoke College 4 NASA Lunar ScienceInstitute Southwest Research Institute 5 Northern ArizonaUniversity 6 Planetary Science Institute 7 School of EarthSciences China University of Geosciences (Wuhan)

21507 ndash The Lunar Reconnaissance Orbiter - SixYears of Science and Exploration at the MoonThe LRO mission currently in an extended mission phase isproducing a remotely sensed dataset that is unrivaled in planetaryscience With an ever-increasing baseline of measurements theLRO data has revealed the Moonrsquos surface and environment to bedynamic with new craters and distal ejecta variations in volatiles atand near the surface a variable exosphere and a surface thatresponds to variations in the flux of radiation from the Sun Takentogether the LRO dataset has significant value in forming how weunderstand airless bodies work in the Solar System and howplanets evolve We will discuss recent observations from themission including geologically recent volcanism contemparayimpacts and polar volatilesWe will also discuss the missions support of future exploration ofthe Moon As initially conceived one of the primary objectives forthe Lunar Reconnaissance Orbiter (LRO) was to identify safelanding sites for future human and robotic exploration and LROmission remains capable of targeted high resolution observationsto support the planning of future robotic missions to the MoonThe LRO team seeks to engage with mission planners to discussLROs enabaling capabilities

Author(s) John W Keller Noah E Petro Timothy PMcClanahan Richard R VondrakInstitution(s) 1 NASAGoddard Space Flight Center

21508 ndash Secondary electron emission from lunar soil

by solar wind type ion impact LaboratorymeasurementsIntroduction The lunar surface potential is determined bytime-varying fluxes of electrons and ions from the solar windphotoelectrons ejected by UV photons cosmic rays andmicrometeorite impacts Solar wind ions have a dual role in thecharging process adding positive charge to the lunar regolith uponimpact and ejecting negative secondary electrons (SE) Electronemission occurs when the energy from the impacting ion istransferred to the solid ionizing and damaging the materialelectrons with kinetic energy greater than the ionization potential(band gap + electron affinity) are ejected from the solid[1]Experiment We investigate the energy distribution of secondaryelectrons ejected from Apollo soils of varying maturity and lunaranalogs by 4 keV He Soils are placed into a shallow Al cup andcompressed In-situ low-energy oxygen plasma is used to cleanatmospheric contaminants from the soil before analysis[2] X-rayphotoelectron spectroscopy ascertains that the sample surface isclean Experiments are conducted in a PHI 560 system (lt10Torr) equipped with a double-pass cylindrical-mirror electronenergy analyzer (CMA) and μ-metal shield The spectrometer isused to measure SE distributions as well as for in situ surfacecharacterization A small negative bias (~5V) with respect to thegrounded entrance grid of the CMA may be placed on the sampleholder in order to expose the low energy cutoffTo measure SEenergy distributions primary ions rastered over a ~6 x 6 mm areaare incident on the sample at ~40deg relative to the surface normalwhile SE emitted with an angle of 423degplusmn 35deg in a cone areanalyzedResults The energy distribution of SE ejected from 4 keV He ionirradiation of albite with no bias applied shows positive charging ofthe surface The general shape and distribution peak (~4 eV) areconsistent with spectra for low energy ions on insulatingmaterial[1]Acknowledgements We thank the NASA LASER program forsupportReferences [1]P Riccardi R Baragiola et al (2004) SurfScience 57 L305-L310 [2]CA Dukes amp RA Baragiola (2010)Surface Interface Anal 42 40-44

Author(s) Catherine Dukes Caixia Bu Raul A BaragiolaInstitution(s) 1 Univ Of Virginia

21509 ndash Comparison of Computational Techniquesfor Estimating Solar Wind Ion Sputtering Yields onSilicatesBodies in space containing silicates and oxides continuouslyexperience ion collisions that result in surface sputteringKnowledge of sputter yields allows for the estimation of destructionrates of small grains in protoplanetary clouds and predictions ofexosphere densities around small bodies to be carried outHowever sputter yields for astrophysical type materials are poorlyconstrained and there has been little work to comparecomputational models to experimental results Theoretical modelsusing sputtering yields commonly use the software SRIM tosimulate ion implantation into solids However the program hasbeen shown to give results that are in poor agreement withexperimental data for low energy (lt10 keV) incident ions typical ofthe solar windHere we compare predicted sputtering yields from SRIM and aprogram based on the TRIMSp algorithm called SDTrimSP Bothprograms were designed to simulate atomic collisions inamorphous targets with predefined stoichiometric compositionsand atomic binding energies During the simulation a onedimensional target is exposed to an incident beam of particles witha composition and energy determined by the user The binarycollision approximation is used to handle the collisions and theenergy loss of the incident particle and energy gain of the recoil isthen calculated This process is repeated for resulting collisionsuntil all particle energies fall below a preset value or have left thetarget However SDTrimSP can account for changing surfacecomposition with increasing irradiation fluence and also providesthe option to use several different surface binding energy modelsSimulations of H and He irradiation of simple oxides were run

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using both programs at energies in the 01-10 keV range andcompared to published experimental data SDTrimSP was seen todisplay a better agreement with this data than SRIM making it amore reliable method of estimating sputtering yields The modelwas then expanded to simulate more complex meteoritecompositions in order to determine the timescale at whichequilibrium is achieved

Author(s) Adam Hutcherson Micah Schaible RobertJohnsonInstitution(s) 1 University of Virginia

216 ndash Beyond the Moon The LunarCommunity Branches Out21601 ndash NASAs Solar System Exploration ResearchVirtual Institute (SSERVI)NASAs Solar System Exploration Research Virtual Institute(SSERVI) represents a close collaboration between sciencetechnology and exploration and was created to enable a deeperunderstanding of the Moon and other airless bodies SSERVI issupported jointly by NASArsquos Science Mission Directorate andHuman Exploration and Operations Mission Directorate Theinstitute currently focuses on the scientific aspects of explorationas they pertain to the Moon Near Earth Asteroids (NEAs) and themoons of Mars but the institute goals may expand depending onNASAs needs in the future The 9 initial teams selected in late2013 and funded from 2014-2019 have expertise across the broadspectrum of lunar NEA and Martian moon sciences Theirresearch includes various aspects of the surface interiorexosphere near-space environments and dynamics of thesebodiesNASA anticipates a small number of additional teams to be selectedwithin the next two years with a Cooperative Agreement Notice(CAN) likely to be released in 2016 Calls for proposals are issuedevery 2-3 years to allow overlap between generations of instituteteams but the intent for each team is to provide a stable base offunding for a five year period SSERVIs mission includes acting asa bridge between several groups joining together researchers from1) scientific and exploration communities 2) multiple disciplinesacross a wide range of planetary sciences and 3) domestic andinternational communities and partnershipsThe SSERVI central office is located at NASA Ames ResearchCenter in Mountain View CA The administrative staff at thecentral office forms the organizational hub for the domestic andinternational teams and enables the virtual collaborativeenvironment Interactions with geographically dispersed teamsacross the US and global partners occur easily and frequently ina collaborative virtual environment This poster will provide anoverview of the 9 current US teams and international partners aswell as information about outreach efforts and future opportunitiesto participate in SSERVI

Author(s) Yvonne J PendletonInstitution(s) 1 NASA Ames Research Center

21602 ndash Extending the Lunar Mapping and ModelingPortal ndash New Capabilities and New WorldsNASArsquos Lunar Mapping and Modeling Portal (LMMP) provides aweb-based Portal and a suite of interactive visualization andanalysis tools to enable mission planners lunar scientists andengineers to access mapped lunar data products from past andcurrent lunar missions (httplmmpnasagov) During the pastyear the capabilities and data served by LMMP have beensignificantly expanded New interfaces are providing improvedways to access and visualize data Many of the recentenhancements to LMMP have been specifically in response to therequirements of NASAs proposed Resource Prospector lunarrover and as such provide an excellent example of the applicationof LMMP to mission planningAt the request of NASArsquos Science Mission Directorate LMMPrsquostechnology and capabilities are now being extended to additionalplanetary bodies New portals for Vesta and Mars are the first of

these new products to be releasedOn March 31 2015 the LMMP team released Vesta Trek(httpvestatrekjplnasagov) a web-based application applyingLMMP technology to visualize the asteroid Vesta Data gatheredfrom multiple instruments aboard Dawn have been compiled intoVesta Trekrsquos user-friendly set of tools enabling users to study theasteroidrsquos featuresReleased on July 1 2015 Mars Trek replicates the functionality ofVesta Trek for the surface of Mars While the entire surface of Marsis covered higher levels of resolution and greater numbers of dataproducts are provided for special areas of interest Early releasesfocus on past current and future robotic sites of operation Futurereleases will add many new data products and analysis tools asMars Trek has been selected for use in site selection for the Mars2020 rover and in identifying potential human landing sites onMarsOther destinations will follow soon The Solar Sytem ExplorationResearch Virtual Institute which manages the project invites theuser community to provide suggestions and requests as thedevelopment team continues to expand the capabilities of theseportalsThis presentation will provide an overview of all three portalsdemonstrate their uses and capabilities highlight new featuresand preview coming enhancements

Author(s) Brian Day Emily LawInstitution(s) 1 NASA AMES Research Center 2 NASA Jetpropulsion Laboratory

217 ndash Venus21701 ndash Ionospheric Modulation of Venus ExpressLightning Detection RatesVenus Express completed its nearly 9 year campaign at Earthrsquossister planet in late 2014 During this period the onboard fluxgatemagnetometer collected data up to 64 Hz in frequency while nearperiapsis This is the expected frequency range for lightning-generated whistler-mode waves at Venus between the localelectron and ion gyrofrequencies These waves are right-handcircularly polarized and are guided by the local magnetic fieldWhen the Venusian ionopause is low enough in altitude to residein the collisional region the interplanetary magnetic field can getcarried down with the ions and magnetize the lower ionosphere Asthe field travels towards the terminator it gains a radial componentenabling whistlers to reach higher altitudes and be detected by thespacecraftThe mission covered almost an entire solar cycle and frequentlyobserved a magnetized ionosphere during the solar minimumphase when the ionosphere was weak due to reduced incidentEUV Detection was most common at 250 km altitude where thewaves travel more slowly due to reduced ionospheric density Inresponse they increase in amplitude in order to conserve magneticenergy flux Here we examine the changes in the ionosphericproperties associated with the evolution of the solar cycle and therate of detection of these lightning-generated signals

Author(s) Richard A Hart Christopher T Russell TielongZhangInstitution(s) 1 Austrian Academy of Science 2 University ofCalifornia Los Angeles

21702 ndash Chemistry in the Venus clouds Sulfuric acidreactions and freezing behavior of aqueous liquiddropletsVenus has a thick cloud deck at 40-70 km altitude consisting ofliquid droplets and solid particles surrounded by atmosphericgases The liquid droplets are highly concentrated aqueoussolutions of sulfuric acid ranging in concentration from 70-99 wtWeight percent drops off with altitude (Imamura and Hashimoto2001) There will be uptake of atmospheric gases into the dropletsolutions and the ratios of gas-phase to liquid-phase species willdepend on the Henryrsquos Law constant for those solutions Reactionsof sulfuric acid with these gases will form products with differing

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solubilities For example uptake of HCl by H SO H O dropletsyields chlorosulfonic acid ClSO H (Robinson et al 1998) insolution This may eventually decompose to thionyl- or sulfurylchlorides which have UV absorbances HF will also uptakecreating fluorosulfonic acid FSO H which has a greater solubilitythan the chloro- acid As uptake continues there will be manydissolved species in the cloudwaters Baines and Delitsky (2013)showed that uptake will have a maximum at ~62 km and this isvery close to the reported altitude for the mystery UV absorber inthe Venus atmosphere In addition at very strong concentrationsin lower altitude clouds sulfuric acid will form hydrates such asH SO H O and H SO 4H O which will have very differentfreezing behavior than sulfuric acid with much higher freezingtemperatures (Carslaw et al 1997) Using temperature data fromVenus Express from Tellmann et al (2009) and changes in H SOconcentrations as a function of altitude (James et al 1997) wecalculate that freezing out of sulfuric acid hydrates can besignificant down to as low as 56 km altitude As a result balloonsaircraft or other probes in the Venus atmosphere may be limited toflying below certain altitudes Any craft flying at altitudes above~55 km may suffer icing on the wings propellers balloons andinstruments which could cause possible detrimental effects(thermal changes reduced buoyancy effects on control surfacesplugging of sample inlets etc) Therefore de-icing equipmentshould be considered when designing aircraft expected to fly athigh altitudes in the Venus clouds

Author(s) M L Delitsky K H BainesInstitution(s) 1 California Specialty Engineering 2 Universityof Wisconsin

21703 ndash Venus Atmospheric Maneuverable PlatformScience MissionOver the past several years we have explored a possible newapproach to Venus upper atmosphere exploration by applyingrecent Northrop (non-NASA) development programs and havecome up with a new class of exploration vehicle an atmosphericrover We will discuss a possible suite of instruments andmeasurements to study the current climate through detailedcharacterization of cloud level atmosphere and to understand theprocesses that control climate on Earth-like planetsOur Venus atmospheric rover concept the Venus AtmosphericManeuverable Platform (VAMP) is a hypersonic entry vehicle withan ultra-low ballistic coefficient that transitions to a semi-buoyantair vehicle (AV) after entering the Venus atmosphere Prior toentry the AV fully deploys to enable lifting entry and eliminates theneed for an aeroshell The mass savings realized by eliminating theaeroshell allows VAMP to accommodate significantly moreinstruments compared to previous Venus in situ explorationmissions VAMP targets the global Venus atmosphere between50ndash65 km altitudes and would be an ideal stable platform foratmospheric and surface interaction measurements We willpresent a straw man concept of VAMP including its scienceinstrument accommodation capability and platformrsquos physicalcharacteristics (mass power wingspan etc) We will discuss thevarious instrument optionsVAMPrsquos subsonic flight regime starts at ~94 km and after lt1 hourthe AV will reach its cruise altitude of ~65 km During this phase offlight the VAMP sensor suite will acquire a pre-defined set ofupper atmosphere measurements The nominal VAMP lifetime atcruise altitude is several months to a year providing numerouscircumnavigation cycles of Venus at mid-latitude The stability ofthe AV and its extended residence time provide the very longintegration times required for isotopic mass analysis VAMPcommunicates with the orbiter which provides data relay andpossibly additional science measurements complementing the insitu measurements from the AV We will specifically focus uponkey factors impacting the design and performance of VAMPscience

Author(s) Ronald S Polidan Gregory Lee Floyd Ross Daniel Sokol Linden BolisayInstitution(s) 1 L-Garde 2 Northrop Grumman AerospaceSystems

21704 ndash Some questions about the Venus atmospherefrom past measurementsThe many missions undertaken in the past half a century to exploreVenus with fly-by spacecraft orbiters descending probes landersand floating balloons have provided us with a wealth of data Thesedata have been supplemented by many ground based observationsat reflected solar wavelengths short and long wave infrared to radiowaves Inter-comparison of the results from such measurementsprovide a good general idea of the global atmosphere Howeverre-visiting these observations also raises some questions about theatmosphere that have not received much attention lately butdeserve to be explored and considered for future measurementsThese questions are about the precise atmospheric composition inthe deep atmosphere the atmospheric state in the loweratmosphere the static stability of the lower atmosphere the cloudsand hazes the nature of the ultraviolet absorber and wind speedand direction near the surface from equator to the pole Theanswers to these questions are important for a betterunderstanding of Venus its weather and climate Themeasurements required to answer these questions require carefuland sustained observations within the atmosphere and fromsurface based stations Some of these measurements should andcan be made by large missions such as Venera-D (Russia) VenusClimate Mission (Visions and Voyages ndash Planetary Science DecadalSurvey 2013-2022 or the Venus Flagship Design ReferenceMission (NASA) which have been studied in recent years but somehave not been addressed in such studies For example the fact thatthe two primary constituents of the Venus atmosphere ndash CarbonDioxide and Nitrogen are supercritical has not been considered sofar It is only recently that properties of binary supercritical fluidsare being studied theoretically and laboratory validation is neededWith the end of monitoring of Venus by Venus Express orbiter inNovember 2014 after nearly a decade of observations and theimminent insertion of JAXArsquos Akatsuki spacecraft into orbitaround Venus it is a good moment to consider the unanswered orunexplored questions about Venus

Author(s) Sanjay LimayeInstitution(s) 1 University of Wisconsin

21705 ndash Long-term variations of carbon monoxideand trace species in the Venus troposphere fromVenus ExpressVIRTIS between 2006-2009The understanding of spatial and temporal variations intropospheric abundances of trace gases such as carbon monoxide iskey to understanding the deep atmosphere of Venus These gasesare entrained in the global circulation as well as being keyingredients to creating the sulfuric acid clouds Long-termtemporal variations of these species across Venusrsquos disc would beprovide key insights into the large-scale circulation and cloudforming processes in the troposphereThe Venus Express spacecraft orbited Venus from April 2006 toDecember 2014 The VIRTIS instrument is a near-infrared imagingspectrometer that covers 03 to 50 microm Nightside thermalemissions at 232 microm is sensitive to CO at 35 km We present longterm abundances of CO and other trace abundances as observed byVIRTIS from April 2006 through October 2008 when the MIRchannel ceased operations We compare the methods of Tsang etal (2009) and Barstow et al (2012) of deriving CO from bandratios We will also provide long-term variations of cloud particlesizes This work is done in conjunction with a study of long-termvariations of 173 microm thermal emission brightnesses a proxy ofcloud optical depth in the lower atmosphere with the same data(McGouldrick and Tsang 2015) This work is supported by NASArsquosPlanetary Mission Data Analysis Program grant numberNNX14AP94G

Author(s) Constantine Tsang Kevin McGouldrickInstitution(s) 1 Southwest Research Institute 2 University ofColorado

21706 ndash Ground-Based Venusian Thermal Structureand Dynamics Observations in August 2010We measured equatorial winds above the cloud tops of Venus and

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in the lower thermosphere over 19-23 Aug 2010 (UT) a componentof a Venus measurement program that extends over ~30+ yearsusing ground-based Infrared Heterodyne Spectroscopy (IRHS)IRHS obtains sub-Doppler resolution on molecular transitions ofatmospheric species We used the Heterodyne Instrument forPlanetary Winds and Composition (HIPWAC NASA GoddardSpace Flight Center) at the NASA Infrared Telescope Facility toacquire high-resolution spectra on pressure-broadened COabsorption featuresprobing the lower mesosphere (70 km altitude)with non-LTE core emission that probes the lower thermosphere(110 km) The two features probe the transition from zonal windflow near the cloud tops to subsolar-to-antisolar flow in thethermosphere Fully resolved carbon dioxide transitions weremeasured near the 9528808 cm (10494 microm) rest frequency atresolving power λΔλ = 25times10 on the equator on positionsdistributed about the central meridian and across the terminator at~15deg intervals in longitude The non-LTE emission is solar-pumped and appears only on the daylight side probing subsolar-to-antisolar wind velocity flowing radially from the subsolar pointthrough the terminator which was near the central meridian inthese observations with maximum tangential velocity but zeroline-of-sight projection at the terminator and zero tangentialvelocity but maximum projection at the limb The maximummeasurable Doppler shift thus appears within the disc betweencentral meridian and limb The velocity of the zonal flow isapproximately uniform with constant tangential velocity andmaximum line-of-sight projection at the limb and can bemeasured by the frequency of the absorption line on both thedaylight and dark side Variations in Doppler shift between theobservable features and the differing angular dependence of thecontributing wind phenomena thus provide independentmechanisms to distinguish dynamical processes at the altitude ofeach observed spectral feature Winds up to gt100 ms weredetermined in previous investigations with uncertainties of order10 ms or less This work was supported by the NASA PlanetaryAstronomy Program

Author(s) Tilak Hewagama Theodor Kostiuk TimothyLivengood Tobias Stangier Kelly Fast John Annen ManuelaSornig Pia KrauseInstitution(s) 1 DLR and Univ of Cologne 2 NASA 3NASAGoddard Space Flight Center 4 NASAGoddard SpaceFlight Center (Retired) 5 Univ of Maryland 6 University ofCologne

21707 ndash The Role of Rheological Weakening in theFormation of Narrow Rifts on VenusThe rift zones on Venus are remarkably similar to those seen onEarth despite Venusrsquo current lack of plate tectonics The DevanaChasma rift on Beta Regio accommodates extension in a narrowzone and is associated with volcanism As a result it has often beencompared to the East African Rift (Burov and Gerya 2014 Fosterand Nimmo 1996) It has been suggested that plate boundariesdevelop on Earth because an interconnected network of localizedshear zones (areas of concentrated weakening) can form throughthe lithosphere (Regenauer-Lieb and Yuen 2001) If Venusianrifts such as Devana Chasma are similar to terrestrial plateboundaries then it is possible that shear zones should form inthose locationsMontesi (2013) showed that water-bearing minerals such asmicas which are probably not present on Venus largely dominateweakening in the Earthrsquos crust On Venus melts are likely to playthe role of the weak phase that allows for localization due to its lowviscosity relative to host rocks Weakening due to grain sizereduction is also possible if a dislocation-accommodated grainboundary sliding mechanism is active on Venus (Montesi 2013)Rift stability for Venus-like conditions has been analyzed using themodel of Buck (1991) This model links the evolution oflithospheric strength with the style of rifting (wide narrow ormetamorphic core complex) The crust and mantle are assumed tobe dry diabase and dry olivine respectively (diabase rheologicalparameters are from Mackwell et al (1998) olivine rheologicalparameters are from Hirth and Kohlstedt (2003)) The crustalthickness and surface heat flux are varied based on estimatedvalues from the literature (Nimmo and McKenzie 1998 Buck

2002) Without the inclusion of a weakening mechanism the largemajority of model runs predict wide rifts developing Adding asimplistic exponential decay to the lithospheric yield strengthallows for more narrow rift formation to occur Including explicitweakening processes which may be associated with grain sizereduction or development of a foliation appears necessary toexplain the presence of narrow rifts on Venus

Author(s) Alexis Martone Laurent MontesiInstitution(s) 1 University of Maryland College Park

21708 ndash Reflection and Emission Spectra of Fe-OxidesUnder Venus-Like ConditionsThe Solar Systemrsquos last solid planet for which we have nomineralogy data is Venus Soviet landers acquired images andelemental abundances at six locations on the surface of Venusγ-ray and XRF spectroscopy performed by the landers showed thatthe plains are made of mafic basalts Very large concentrations of Kat the Venera 8 and 13 landing sites indicated the presence ofalkaline basaltsNear-IR and thermal IR remote sensing of Mars both from orbitand at the surface have revealed the layered mineralogicalcomplexity of that planet Dominated by basalts and a wide-varietyof fluid-altered phases the mineralogy of Mars tells a complexstory of wet and dry epochs in a history of dramatic climate changeAt the surface of Venus optical pathlengths are small and there islittle scattering due to hazes The environment around a lander orrover on Venus can be mapped from 04 to 3 μm just as well as ithas been on Mars Laboratory spectra show that the ferric edge at055 μm that makes Mars red shifts to 1 μm at Venus surfacetemperatures (Pieters et al 1986) This spectral feature is causedby strong charge transfer transitions in the UV betweenoverlapping orbitals of iron and oxygen and crystal-field electronictransition bands of ferric Fe (Pieters and Englert 1993) Pressureand temperature will alter and broaden crystal-field electronictransition bands Johnson and Fegley (2000) showed that ahalogenatedhydrated amphibole (tremolite) is metastable onVenus thus metamorphic remnants of an ancient hydrospherecould still exist In future work the reflectance and emission spectraof this phase will also be studied at high temperaturesWe will present reflection and emission spectra of severalFe-oxides up to 450degC and 100 bars These environmentalconditions are programmable in a small off-the-shelf 1 cc chamberthat sits in the optical path of a Nicolet FTIR spectrometer Ourwork will show that ambient pressure and temperature havesignificant effects on Fe-oxide spectra and that both must beunderstood to use near-IR spectroscopy to diagnose themineralogy near a Venus lander

Author(s) Mark A Bullock Con CC Tsang Dan D Durda Jeffrey S KargelInstitution(s) 1 Southwest Research Inst 2 University ofArizona

21709 ndash An Induced Venusian Magnetosphere Modelfor Investigating Venusrsquos InteriorThe deep layers of Venus are usually considered to be similar tothose of the Earth but the parameters of these layers including thesize of the Venusian core remain unknown If Venus has a metalliccore the magnetic field that enters the planet cannot diffuse intothe core within the time scales when the external magnetic field canremain steady The bending of magnetic field lines by the corecould be measured at low altitudes providing information to inferthe core size This method of magnetic sounding has successfullyestimated the size of the lunar core helped by the fact that theEarthrsquos magnetotail can provide a uniform background magneticfield for the Moon At Venus the magnetic field is much morecomplicated as the solar wind interaction with the planet developsan induced magnetosphere Estimating the magnetic induction bythe core in this non-uniform non-axisymmetric magnetic fieldenvironment also requires numerical computationThis study develops an induced Venusian magnetosphere modelthat is suitable for understanding Venusrsquos interior Different fromthe global plasma models this model includes the planetary

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interior in the model domain A tradeoff is the use of magnetostaticequations which enables faster computation in return Thisapproach is similar to that adopted by popular empirical models forthe terrestrial magnetosphere Improved from our previous 2-Dmodel the new 3-D model consists of a conducting core the Venuscounterpart of the Chapman-Ferraro current and the tail currentsheet In a separate scenario a global dipole moment is alsoconsidered The finite element method is used to compute themagnetic field vectors within the induced Venusian magnetopauseWe will present model results as well as their comparisons with themagnetic field measurements by PVO and by the more recent VEXmission

Author(s) Peter J Chi Christopher T Russell Michaela NVillarreal Janet G Luhmann T L ZhangInstitution(s) 1 Department of Earth Planetary and SpaceSciences UCLA 2 Space Research Institute Austrian Academy ofSciences 3 Space Sciences Laboratory University of CaliforniaBerkeley

218 ndash Planetary Rings21801 ndash Investigations of Saturnrsquos Main Rings overBroad Range of WavelengthsAn abundance of information about the characteristics of Saturnrsquosring particles and their regolith can be obtained by comparing thechanges in their brightness color and temperature with changingviewing geometry over a wide range of wavelengths from ultravioletthrough the thermal infrared Data from Cassinirsquos CompositeInfrared Spectrometer (CIRS) Visual and Infrared MappingSpectrometer (VIMS) Imaging Science Subsystem (ISS) andUltraviolet Imaging Spectrograph (UVIS) are jointly studied usingdata from the lit and unlit main rings at multiple geometries andsolar elevations over 11 years of the Cassini mission Using multi-wavelength data sets allows us to test different thermal models bycombining the effects of particle albedo regolith grain size andsurface roughness with thermal emissivity and inertia particle spinrate and spin axis orientationCIRS temperatures ISS colors and UVIS brightness appear to varynoticeably with phase angle but are not a strong function ofspacecraft elevation angle Color temperature and brightnessdependence on solar elevation angle are also observed VIMSobservations show that the infrared ice absorption band depthschange with the solar phase angle in particular between 0-20deg andat high phase This trend indicates that single scatteringapproximation is correct only at low phases (lt20deg) while at highphase multiple scattering must be taken into accountThese results imply that the individual properties of the ringparticles may play a larger role than the collective properties of therings in particular at visible wavelengths The temperature andcolor variation with phase angle may be a result of scattering withinthe regolith as well as scattering between individual particles orclumps in a many-particle-thick layer Initial results from our jointstudies will be presentedThis research was carried out in part at the Jet PropulsionLaboratory California Institute of Technology under contract withNASA Copyright 2015 California Institute of TechnologyGovernment sponsorship is acknowledged

Author(s) Linda J Spilker Estelle Deau RyujiMorishima Gianrico Filacchione Matt Hedman PhilNicholson Josh Colwell Todd Bradley Mark Showalter StuPilorz Shawn Brooks Mauro Ciarniello Institution(s) 1 Cornell University 2 Idaho University 3INAF-IAPS 4 JPL 5 SETI Institute 6 UCLA 7 University ofCentral Florida

21802 ndash Multi-frequency VLA Observations ofSaturnrsquos RingsWe will present the calibration and analysis of recent VLAobservations on Saturn and its rings at Q K Ku and X band (07 ndash36 cm) These observations were collected in January 2015 using8-hr tracks in the CnB array configurations to map the system at

high spatial resolution (comparable to the resolution of availablemicrowave Cassini datasets) while remaining sensitive to largescale structure These data complement and extend Cassiniobservations obtained with its 22-cm radiometer The significantreduction in the emissivity of water-ice at 36 cm relative to that at07 cm results in a strong differential response to the fractionalabundance of non-icy material in the rings which is observablewith VLA The VLA data will confirm and extend our previousnon-icy material distributions derived from Cassini data Increasednon-icy material contamination and changes in the particle sizedistribution affect the brightness temperatures noticeablydifferently at shorter wavelengths (07 - 2 cm) Therefore themulti-wavelength nature of the VLA dataset will enable us todisentangle brightness temperature variations from changes in theparticle size distribution and non-icy material abundance We willpresent an update on the analysis of both the VLA dataset as well asthe ongoing analysis of the Cassini observations

Author(s) Zhimeng Zhang Alexander Hayes Imke dePater Phillip Nicholson Michael Janssen Jeffrey Cuzzi David Dunn Bryan ButlerInstitution(s) 1 Ames Research Center 2 Cornell University 3Jet Propulsion Laboratory 4 National Radio AstronomyObservatory 5 Sierra College 6 University of California atBerkeley

21803 ndash Heating Saturns Clumpy RingsWe model Cassini CIRS data using a Monte Carlo radiative transfer-- thermal balance technique first developed for protostellar diskswith the goals of1 Exploring whether the A- and B-ring temperatures variationwith viewing angle is consistent with the wake structures suggestedby the observed azimuthal asymmetry in optical depth by analyticarguments and by numerical N-body modeling2 Better constraining the shape size spacing and optical depths ofsubstructure in the A-ring using the unexpectedly hightemperatures observed at equinox If the wake features have highenough contrast Saturn-shine may penetrate the gaps between thewakes and heat thering particles both top and bottom3 Determining how much of the heating of the A- and B-ringsunlit sides is due to radiative transport and how much is due toparticle motions especially vertical motions This will help inconstraining the rings surface densities and masses

Author(s) Neal J Turner Ryuji Morishima Linda JSpilkerInstitution(s) 1 JPLCaltech 2 UCLA IGPP

21804 ndash Detections of Propellers in Saturns Ringsusing Machine Learning Preliminary ResultsWe report on the initial analysis of the output of a tool designed toidentify persistent non-axisymmetric features in the rings ofSaturn This project introduces a new paradigm for scientificsoftware development The preliminary results include what appearto be new detections of propellers in the rings of SaturnThe Planetary Data System (PDS) working with the NASATournament Lab (NTL) Crowd Innovation Lab at HarvardUniversity and the Topcoder community at Appirio Inc underthe umbrella ldquoCassini Rings Challengerdquo sponsored a set ofcompetitions employing crowd sourcing and machine learning todevelop a tool which could be made available to the community atlarge The Challenge was tackled by running a series of separatecontests to solve individual tasks prior to the major machinelearning challenge Each contest was comprised of a set ofrequirements a timeline one or more prizes and other incentivesand was posted by Appirio to the Topcoder Community In the caseof the machine learning challenge (a ldquoMarathon Challengerdquo on theTopcoder platform) members competed against each other bysubmitting solutions that were scored in real time and posted to apublic leader-board by a scoring algorithm developed by Appirio forthis contestThe current version of the algorithm was run against ~30000 ofthe highest resolution Cassini ISS images That set included 668

1 11 3 2

4 56 3 2

1 7 7 55 4 3

2 26 2 3 1

5 4

1 21

65

images with a total of 786 features previously identified aspropellers in the main rings The tool identified 81 of thosepreviously identified propellers In a preliminary closeexamination of 130 detections identified by the tool we determinedthat of the 130 detections 11 were previously identified propellerdetections 5 appear to be new detections of known propellers and4 appear to be detections of propellers which have not been seenpreviously A total of 20 valid detections from 130 candidatesimplies a relatively high false positive rate which we hope to reduceby further algorithm development The machine learning aspect ofthe algorithm means that as our set of verified detections increasesso does the pool of ldquoground-truthrdquo data used to train the algorithmfor future use

Author(s) Mitchell K Gordon Mark R Showalter Jennifer Odess Ambi Del Villar Andy LaMora Jin Paik Karim Lakhani Rinat Sergeev Kristen Erickson Carol Galica

Edwin Grayzeck Thomas Morgan William Knopf Institution(s) 1 Appirio Inc 2 Carl Sagan Center SETIInstitute 3 Crowd Innovation LabNASA Tournament Lab atHarvard University 4 Goddard Space Flight Center 5 NASAHeadquarters

21805 ndash Characteristics of Small Scale WaveStructure Near Strong Janus Inner LindbladResonancesRegions of compression and rarefaction within Saturnrsquos ringsinclude Inner Lindblad Resonances (ILR) at spiral density wavesand spiral bending waves at vertical resonances along withsmaller-scale self-gravity and overstability waves However fewinvestigations have searched for structure at scales under 100metersWe investigate Cassini UVIS HSP stellar occultation profilescollected between May 19 2005 and June 2 2013 (Cassinirevolutions 8 - 191) within and near strong A ring and B ring spiraldensity waves We report an unexpected number of statistically-significant gaps in ring optical depth within the density wavesgenerated at strong resonances While the frequency of gaps differsacross resonance locations size distribution power laws at similarregions have similar indices We compare the frequency of gapsbetween the peaks troughs and intermediate regions of the ILRspiral density waves

Author(s) Zarah Brown Morgan Rehnberg LarryEsposito Nicole Albers Miodrag SremčevićInstitution(s) 1 University of Colorado BoulderLASP

21806 ndash Direct numerical modeling of Saturns denserings at high optical depthSaturns B ring exhibits complex optical depth structure ofuncertain origin We are investigating the extent to which viscousoverstability andor gravitational wakes can give rise to thisstructure via discrete particle numerical simulations We use theparallelized N-body tree code pkdgrav with a soft-sphere collisionmodel for detailed treatment of particle collisional physicsincluding multi-point persistent contact with static sliding rollingand twisting friction forces This enables us to perform localsimulations with millions of particles realistic sizes andconfigurable material properties in high-optical-depth ring patcheswith near-linear scaling across multiple processors Recent codeimprovements to the collision search algorithm provide a furtherroughly factor of 2 speedup We present results from the first yearof this study in which a library of simulations with different opticaldepths was constructed Parameters explored include normal(dynamical) optical depths between 05 (approximately 100000particles) and 40 (approximately 83 million particles) in ringpatches of dimension 6 by 6 critical Toomre wavelengths usingmaterial parameters ranging from highly elastic smooth spheres torough gravel-like particles We also vary the particle internaldensities to enhance (low density)suppress (high density) viscousoverstability in order to compare against gravitational instability inthese different regimes These libraries will be used to carry outsimulated observations for comparison with Cassini CIRStemperature measurements and UVIS occulation data of Saturns

dense rings

Author(s) Derek C Richardson Ronald-Louis Ballouz Ryuji MorishimaInstitution(s) 1 Univ of California 2 Univ of Maryland

21807 ndash A survey of the Saturnian ring edges Resultsfrom double star occultationsThe Cassini Ultraviolet Imaging Spectrograph (UVIS) High SpeedPhotometer (HSP) has recorded more than 150 stellar occultationsof Saturns rings About one third are observations involvingdouble stars where each star contributes its own independentlight curve For each light curve its footprint as projected into thering plane and depending on observation geometry samples adifferent region in the ring Here we focus on ring edges Eachoccultation then yields two independent edge measurements at twodifferent times and longitudes We infer relative changes in opticaldepth and radial position over an azimuthal distance as short as 20meters These relative measurements require neither photometricnor geometric calibration and inform on the small-scale variabilityof structurefeatures with relative resolutions an order ofmagnitude higher than typically achievedThe Encke and Keeler gap edges as well as the outer B and A ringedges show radial excursions on the order of tens of meters Theseradial variations are in comparison to the common multi-modeanalysis of edge kinematics high-frequency components withcorresponding m numbers of mgt5000000 We note that spatialdimensions inferred here are 10-100 times smaller than those offeatures Region A and B at the B ring edge or Peggy-type objectsat the A ring edge and are comparable to individual self-gravitywakes or clumpsparticles The Titan and Huygens ringlets innerand outer edges on the other hand are in comparison highlyregular and smooth with radial variations of only a few metersNevertheless they show changes in normal optical depth on theorder of 04 well above the expected margin due to intrinsic stellarvariability We also identified three features in the C ring that showlittle radial variability and can thus be considered smoothInterestingly this irregularity or raggedness of the edges -manifestation of intrinsic small-scale structure of the ring - isstronger with increasing radial distance from Saturn This isconsistent with the current understanding that larger structuresform in regions of weaker tidal forces or perturbed regions such asthe A and B ring edgesThis work is supported by the Cassini project

Author(s) Nicole AlbersInstitution(s) 1 LASPUniversity of Colorado

21808 ndash Modeling Cassini Occultations for HighResolution Simulations of Saturnrsquos RingsWe present the preliminary results of attempts to accurately modelCassini occultations numerically with high-resolution patchsimulations of Saturnrsquos rings The simulations use particledistributions that match measurements of surface densities fromdensity waves and particle sizes distributions that extend down toradii of a decimeter or smaller Synthetic occultationmeasurements are produced using ray tracing techniques withgeometries that match those of various Cassini observations forcomparison

Author(s) Mark C Lewis Josh E ColwellInstitution(s) 1 Trinity Univ 2 University of Central Florida

21809 ndash Simulating ldquoStrawrdquo in the Keeler Gap RegionPrevious simulations by Lewis and Stewart (2005) indicated thatgravity wakes at the edge of the Encke Gap region could grow tokilometers in length through the systematic motion of the ringmaterial produced by the interaction with Pan Recent simulationsof the Keeler gap region indicate that this same process can occurthere as well if there is sufficient surface density to sustain theclustering of particles These simulations use a single large fixedcell and include the eccentricity and inclination of Daphnis Thesefactors lead to time variability that is not seen at the Encke gap Weshow where and how these form at the Keeler Gap and how they

2 21 1 1 33 3 5

5 4 4 5

1 11 1 1

2 21

1

1 2

66

might appear in occultation and imaging observations

Author(s) Alexander K Hansen Mark C LewisInstitution(s) 1 Trinity University

21810 ndash Physics of Tidal Disruption of Big Objects atthe Close Encounter to SaturnThe origin of Saturns main rings is still debated According to theNice model of Late Heavy Bombardment planets couldexperience significant amount of close encounters with bodiesscattered from primordial Kuiper belt that surrounded the giantplanets Such primordial belt could have been significantly massiveand may have contained a larger number of big objects thancurrently observed in the Kuiper Belt In this work we revisit thephysical processes of tidal disruption of such big object passinginside the Saturns Roche limit and discuss the possibility of themass implantation around Saturn as a result of the tidal disruption[Charnoz et al 2009 Icarus 199 413-428] utilized an analyticalformula that is derived from simply assuming uniform distributionof energy within a body [Dones 1991 Icarus 92 194-203] to obtainmasses that are captured onto bound orbits around planet afterclose encounter However the physical processes of tidaldisruption remained unclear and thus we might need to re-assessthe captured mass In this work we perform SPH simulations ofclose encounters of homogeneous and differentiated bodiesaround Saturn in order to investigate how such objects could betidally destructed and how much mass could be captured aroundSaturn as a result of the destruction We find that our numericalresults are not always consistent with Dones (1991) formula thatin general significantly overestimates or underestimates thecaptured mass as the pericenter distance of the passing objectbecomes larger depending on the mass of objects Effects ofrotation and self-gravity within the body will be also investigatedWe show that there is a wide range of outcomes for tidal disruptionand that the implantation of rings is possible

Author(s) Ryuki Hyodo Seacutebastien Charnoz Keiji Ohtsuki Hidenori GendaInstitution(s) 1 Earth-Life Science Institute Tokyo Institute ofTechnology 2 Institut de Physique du Globe de Paris 3 KobeUniversity

21811 ndash Orbit Averaging in Perturbed Planetary RingsThe orbital period is typically much shorter than the time scale fordynamical evolution of large-scale structures in planetary ringsThis large separation in time scales motivates the derivation ofreduced models by averaging the equations of motion over the localorbit period (Borderies et al 1985 Shu et al 1985) A moresystematic procedure for carrying out the orbit averaging is to useLie transform perturbation theory to remove the dependence onthe fast angle variable from the problem order-by-order in epsilonwhere the small parameter epsilon is proportional to the fractionalradial distance from exact resonance This powerful technique hasbeen developed and refined over the past thirty years in the contextof gyrokinetic theory in plasma physics (Brizard and Hahm RevMod Phys 79 2007) When the Lie transform method is appliedto resonantly forced rings near a mean motion resonance with asatellite the resulting orbit-averaged equations contain thenonlinear terms found previously but also contain additionalnonlinear self-gravity terms of the same order that were missed byBorderies et al and by Shu et al The additional terms result fromthe fact that the self-consistent gravitational potential of theperturbed rings modifies the orbit-averaging transformation atnonlinear order These additional terms are the gravitationalanalog of electrostatic ponderomotive forces caused by largeamplitude waves in plasma physics The revised orbit-averagedequations are shown to modify the behavior of nonlinear densitywaves in planetary rings compared to the previously publishedtheory This reserach was supported by NASAs Outer PlanetsReserach program

Author(s) Glen R StewartInstitution(s) 1 Univ of Colorado

21812 ndash A new look back at the structure of Uranusnarrow ringsWith the Cassini mission to Saturn providing new insights into howrings work a new examination of the available Uranus ring datawill provide further insights into the ringsrsquo structure and dynamicsas well as the planetary interior We investigate the fine-scalequasiperiodic optical depth variations within the Uranian ringsobserved in the Voyager 2 radio and stellar occultations Previousinvestigations of these patterns within the ε δ and γ ringssuggested that some of these may be density waves at locations ofeccentric Lindblad resonances with the satellites Cordelia andOphelia (Porco and Goldreich 1987 AJ) as well as possibleunidentified satellites (Horn et al 1988 Icarus Gresh et al 1989Icarus and Yanamandra-Fisher 1992 ASR) We revisit thesestructures as well as others in the α β 4 5 and 6 rings usingmodern analytical techniques in order to better constrain theirorigins The α and β rings exhibit highly periodic patterns whichhave very different wavelengths in the different occultation cuts(even after accounting for the ringletsrsquo width variations) Weexplore the possibility that these structures could be moonletwakes similar to those found in Saturnrsquos rings near the smallmoons Pan and Daphnis

Author(s) Robert O Chancia Matthew M Hedman RichardG FrenchInstitution(s) 1 University of Idaho 2 Wellesley College

21813 ndash Evolution of regolith depth and fractionalpollution of Saturnrsquos ringsWe model the evolution of the fractional pollution of Saturnrsquosrings by calculating the ratio of exogenous meteoritic material toendogenous icy material native to the ring system Comparison toring spectra can constrain the age of the planetrsquos ring system Weupdate our Markov-chain based model (Elliott and Esposito 2011)to numerically calculate the regolith depth and fractional pollutionof a simulated system of ring particles for a given input meteoriticmass flux distribution into the system over long time scales Weuse new mass flux values recently reported by Kempf et al (EPSC2015) derived from the Cassini Cosmic Dust Analyzer (CDA) tocalculate new fractional pollution values and calculate thebidirectional reflectance spectra using reflectance data of comet67PChuryumovndashGerasimenko obtained by the Alice UVspectrometer onboard the Rosetta spacecraft as the pollutant aswell as several other pollutant species for comparison to CassiniUVIS spectra

Author(s) Joshua Peter Elliott Larry W EspositoInstitution(s) 1 Laboratory for Atmospheric and Space PhysicsUniversity of Colorado 2 National Ecological ObservatoryNetwork

219 ndash EPO - Scientists Showcase Programsand Best Practices21901 ndash Discoveries in the Solar System Spreadingthe Good WordSolar system exploration in recent years has completely capturedthe interest of the public worldwide and we as scientists can play aunique role in disseminating this information The public wants tohear from us about the latest results from the Pluto flyby to see thenewest Titan image to hear stories of the plucky Philae cometlander and to hear our thoughts on the Earth-like exoplanet evenif we are not directly involved in these missions or discoveriesThey trust us because they know our background makes us viablejudges of the value of these endeavors The public relies on us todistill the material which is typically science-jargon-rich intosomething inspiring and digestible by them in the time they haveavailable The best way to start reaching out is to find and distributewhat most excites us because it is clearly obvious when wersquore trulyexcited about something as opposed to just regurgitating the latestand greatest If you like the latest picture from MSL because itlooks like your back yard show a picture of the two next to each

1 1

2 2 31

1

1 12

2 1

67

other We should be familiar with and even solicit the differentoutreach platforms such as such as social media of various kindspublic talks in all shapes and forms news venues including radioand TV and popular articles Finally we need to know ouraudience prepare and practice I have never given the exact sameoutreach talk twice because the audience is always slightlydifferent The last two public talks I gave were carefully wordedpracticed and even partly memorized which gave me an edge ofpreparedness that allowed me to be more dynamic Being involvedin outreach in the best way for you will make you happier andbetter focused in your research will ensure the public supportsNASA and will make a positive impact in the lives of many people

Author(s) Jani RadebaughInstitution(s) 1 Brigham Young University

21902 ndash Exoplanet Science in the National ScienceOlympiadThe National Science Olympiad is one of the United States largestscience competitions reaching over 6000 schools in 48 states TheOlympiad includes a wide variety of events stretching a full rangeof potential future STEM careers from biological sciences toengineering to earth and space sciences The Astronomy event hasbeen a mainstay at the high school level for well over a decade andnominally focuses on aspects of stellar evolution For the2014-2015 competition season the event focus was aligned toinclude exoplanet discovery and characterization along with starformation Teams studied both the qualitative features ofexoplanets and exoplanetary systems and the quantitative aspectsbehind their discovery and characterization including basiccalculations with the transit and radial velocity methods Studentswere also expected to have a qualitative understanding of stellarevolution and understand the differences between classes of youngstars including T Tauri and FU Orionis variables and Herbig AeBestars Based on the successes of this event topic we are continuingthis event into the 2015-2016 academic year The key modificationis the selection of new exoplanetary systems for students toresearch We welcome feedback from the community on how toimprove the event and the related educational resources that arecreated for Science Olympiad students and coaches We alsoencourage any interested community members to contact yourregional or state Science Olympiad tournament directors andvolunteer to organize competitions and supervise events locally

Author(s) Thaddeus D Komacek Donna YoungInstitution(s) 1 NASA Astrophysics Divison 2 University ofArizona

21903 ndash PACA_Rosetta67P Global AmateurObserving Support for ESARosetta MissionThe PACA (Professional - Amateur Collaborative Astronomy)Project is an ecosystem of several social media platforms(Facebook Pinterest Twitter Flickr Vimeo) that takes advantageof the global and immediate connectivity amongst amateurastronomers worldwide that can be galvanized to participate in agiven observing campaign The PACA Project has participated inorganized campaigns such as Comet Observing Campaign(CIOC_ISON) in 2013 and Comet Siding Spring(CIOC_SidingSpring)in 2014 Currently the PACA Project issupporting ESARosetta mission with ground-based observationsof the comet 67PChuryumov-Gerasimenko (CG) through itsperihelion in August 2015 and beyond providing baselineobservations of magnitude and evolution from locations aroundthe globe Comet 67PCG will reach its brightest post-perihelionand pass closest to Earth in November 2015 We will present thevarious benefits of our professional - amateur collaborationdeveloping and building a core astronomer community defining anobserving campaign from basic information of the comet from itsprevious apparitions coordinating with professionals and themission to acquire observations albeit low-resolution but on along timeline while addressing the creation of several scienceproducts such as the variation of its magnitude over time and thechanging morphology We will present some of our results to dateand compare with observations from professionals and previous

apparations of the comet We shall also highlight the challengesfaced in building a successful collaborative partnership between theprofessional and amateur observers and their resolution With thepopularity of mobile platforms and instant connections with peersglobally the multi-faceted social universe has become a vital part ofengagement of multiple communities for collaborative scientificpartnerships and outreach We shall also highlight other cometaryobserving campaigns that The PACA Project has initiated to evolvethis model of collaborative partnerships

Author(s) Padma A Yanamandra-Fisher ClaudiaAlexander Efrain Morales Christiana Feliciano-RiveraInstitution(s) 1 CITJet Propulsion Laboratory 2 JaicoaObservatory 3 Sloohcom 4 Space Science Institute

21904 ndash STEM education for teachers in the RioGrande ValleyWe have worked with elementary and middle school teachers in theRio Grande Valley for the last 10 years bringing Earth and SpaceScience themed workshops to underserved areas of Texas TheTexas curriculum was also changed to include Astronomy andSpace Science requirement in the tests students need to take toprove their academic preparedness The teachers worked through avariety of inquiry-based hands-on activities after a shortpresentation on the background science In order to evaluate oureffectiveness we have asked the teachers to take pre- andpost-workshop tests and we asked them to fill out a self-reflectivesurvey We will report on our experiences what works best with theteachers and in what areas we still have a long way to goThis work was supported by various NASA education grants andCooperative agreements as well as grants provided by the TexasSpace Grant Consortium

Author(s) Judit Gyorgyey Ries Margaret R BaguioInstitution(s) 1 Univ of Texas Austin

21905 ndash Were mass communicating podcasting asoutreachThe New York Times (July 18th 2015) called podcasting thatrarest thing in the technology industry a subset of media showingsustained growth That same article quotes an Edison Researchreport that found that roughly 15 Americans have listened to apodcast in the last month The most popular podcasts receive amillion downloads per episode and over all podcasts the mediannumber of downloads per episode is ~150 (Libsyn statistics) Thepopularity and easy accessibility of podcasts make them an idealvehicle for outreachThere are several excellent podcasts covering planetary scienceincluding Planetary Radio produced by the Planetary SocietyStarTalk Radio several official NASA podcasts and individualefforts such as Al Grauers Travelers in the Night and Jane JonesWhats upSpacepod is a weekly podcast on space exploration that launched inAugust 2015 Episodes feature an expert guest discussing aninteresting aspect of their job for a general audience Episodes havean intimate conversational feel letting the audience hang outwith space scientists and engineers Spacepod has shown stronggrowth since launch and was featured in iTunes New andNoteworthy section Episodes can be found atwwwlistentospacepodcom and the show tweetslisten2spacepod

Author(s) Carolyn R NugentInstitution(s) 1 CaltechIPAC

21906 ndash The Crossroads of Science and FaithWe have recently completed a 4-year project to produce a textbookfor students that uniquely addresses the needs of the Christianhomeschool community It is also relevant for students of otherfaith and non-faith backgrounds Two elements are at workparents want their kids to become mature adults adhering to thefaith of their upbringing and students are challenged when theydont understand how to rationally discuss their beliefs in relationto many current scientific discoveries To add to the polarization a

1

2 1

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1 1

1

68

few scientists have spread an atheistic naturalistic worldviewtogether with their teaching of science as if it was part of scienceitself As a result many parents avoid materials they considercontroversial and students later come to believe they must choosebetween science and their faith The key to bridging this gap areprofessional astronomers who hold to a Christian worldview andwho can speak both languages understanding the complexities ofboth communities The role of science educators is to teachscience not to impose worldviews Science is well received byChristians when it is presented not as a threat to faith but rather asa complementary way to understand God leading to a moreintegrated view of reality Our textbook boasts four hallmarksproviding students with 1) An understanding of the relationshipbetween faith and science with the goal of helping students toidentify and integrate their own worldview 2) Scientificallyreviewed and accurate astronomical information 3) Examples ofscientists who have wrestled with sciencefaith issues and come toa coherent relationship between the two And 4) exercises for thestudents to interact with the material in both faith and scientificareas We hope this will be a resource to help parents who holdtightly to particular ideologies to be less closed to current scientificdiscovery and more excited about how new discoveries can bolsterand enable their faith We will present an overview of ourmaterials the positive experience we have had so far in testing ourmaterials and our goals for future training within the homeschooland church communities For more information about thetextbook see httpwwwglimpseofhissplendorcom

Author(s) Susan D Benecchi Gladys Kober PaulaGossardInstitution(s) 1 Carin University 2 GSFCNASA 3 PlanetaryScience Institute

21907 ndash NASA SMD and DPS Resources for HigherEducation FacultyThe NASA Education and Public Outreach Forums have developedand provided resources for higher education for the past six yearsthrough a cooperative agreement with NASArsquos Science MissionDirectorate Collaborations with science organizations includingAASrsquos Division of Planetary Sciences have resulted in more toolsprofessional training opportunities and dissemination of resourcesfor teaching in the undergraduate classroom Resources have beendeveloped through needs assessments of the community and withinput from scientists and undergraduate instructors All resourcesare freely availableNASA Wavelength (nasawavelengthorg) is a collection of digitalpeer reviewed Earth and space science resources for formal andinformal educators of all levels All resources were developedthrough funding of the NASA Science Mission Directorate and haveundergone a peer-review process through which educators andscientists ensure the content is accurate and useful in aneducational setting Within NASA Wavelength are specific lists ofactivities and resources for higher education faculty Additionallyseveral resources have been developed for introductory collegeclassrooms The DPS Discovery slide sets are 3-slide presentationsthat can be incorporated into college lectures to keep classesapprised of the fast moving field of planetary science(httpdpsaasorgeducationdpsdisc) The ldquoAstro 101 slide setsrdquodeveloped by the Astro Forum are presentations 5-7 slides inlength on a new development or discovery from a NASAAstrophysics mission relevant to topics in introductory astronomycourses of discoveries not yet in textbooks Additional resourcesguides are available for Astro 101 courses and include cosmologyand exoplanets (httpswwwastrosocietyorgeducationresources-for-the-higher-education-audience)Professional development opportunities are available to faculty toincrease content knowledge and pedagogical tools These includeworkshops at scientific meetings and online webinars that arearchived for later viewing For more information visit the SMDEPO community workspace at httpsmdepoorg

Author(s) Sanlyn Buxner Jennifer Grier Bonnie Meinke Nick Schneider Rusty Low Greg Schultz James Manning Andrew Fraknoi Nicholas GrossInstitution(s) 1 Astronomical Society of the Pacific 2 BostonUniversity 3 Foothill College 4 IGES 5 NASA SMD AstroForum 6 Planetary Science Institute 7 Space Telescope ScienceInstitute 8 University of Colorado

21908 ndash Space Scientists in Education and PublicOutreach A Summary of NASA Resources for EffectiveEngagementThe NASA Education and Public Outreach (EPO) Forumsdeveloped and provided resources for scientists through a five-yearcooperative agreement Through this work the Fourms havesupported scientists who are involved in EPO and who wish tobecome involved Forums have conducted interviews facilitatededucation oral and poster sessions provided lsquoHelp Desksrsquo for moreinformation curated activities as well as produced guidespamphlets and tips sheets Our interviews with over 30 planetaryscientists allowed us to identify needs and target gaps in resourcesensuring we could provide scientists with effective support andproducts Interviews were conducted in collaboration with the AASDivision of Planetary Sciences with the goal of betterunderstanding scientistsrsquo requirements barriers attitudes andperception of education and outreach work We collectedinformation about how scientists were engaged in EPO activities(or not) what support they did or did not have what resources theyused in their efforts and what resources they would like to have tosupport and improve their EPO engagement The Forums haveconvened andor supported EPO oral and poster sessions at avariety of annual meetings These sessions allowed scientists tonetwork share lessons learned and become aware of newresources and products These meetings included the DPS AASLPSC AGU ASP IAU and more lsquoHelp Desksrsquo were offered toallow scientists the chance to have extended one-on-oneconversations with EPO providers in order to share theirprograms and learn how to become involved These have beenparticularly popular with early career scientists looking to extendtheir EPO efforts A host of education activities developed by thespace science community have been archived at the NASA siteldquoWavelengthrdquo (nasawavelengthorg) Special lists have beencurated to allow scientists to easily target those activities that fittheir particular needs from engineering to higher education tooutreach at public events Guides information sheets and ldquoHowTorsquosrdquo have been developed to answer specific questions and needsthat scientists have specifically expressed These resources areopenly available at the NASA SMD community site (smdepoorg)

Author(s) Jennifer A Grier Sanlyn Buxner NickSchneider Bonnie Meinke Stephanie ShippInstitution(s) 1 LASPUniversity of Colorado 2 Lunar andPlanetary Institute 3 Planetary Science Institute 4 SpaceTelescope Science Institute

21909 ndash Best Practices in Pulic Outreach EventsIntroductionEach year the National Aeronautics and Space Administration(NASA) sponsors public outreach events designed to increasestudent educator and general public engagement in its missionsand goals NASA SMD Educationrsquos review of large-scale eventsldquoBest Practices in Outreach Eventsrdquo highlighted planning andimplementation best practices which were used by the Dawnmission to strategize and implement its Ceres arrival celebrationevent i C CeresBackgroundThe literature review focused on best identifying practices risingfrom evaluations of large-scale public outreach events Thefollowing criteria guided the study Public science-related events open to adults and children Events that occurred during the last 5 years Evaluations that included information on data collected fromvisitors andor volunteers Evaluations that specified the type of data collectedmethodology and associated results

3 21

6 6 78 4 1 53 2

3 31 4 2

69

Best Practices Planning and ImplementationThe literature review revealed key considerations for planningimplement large-scale events Best practices included can bepertinent for all event organizers and evaluators regardless of eventsize A summary of related best practices is presented below1) Advertise the event2) Use and advertise access to scientists Attendees who reported an interaction with a science professionalwere 15 to 19 more likely to report positive learning impacts(SFA 2012 p 24)3) Recruit scientists using findings such as High percentages of scientists (85 to 96) from most eventswere interested in participating again (SFA 2012)4) Ensure that the event is group and particularly child friendly5) Target specific event outcomesBest Practices Informing Real-world Planning Implementationand EvaluationDawn missionrsquos collaborative design of a series of events i C Ceresincluding in-person interactive events geared to families and livepresentations will be shared with focus on the family event andthe evidence that scientist participation was a particular driver forthe eventrsquos impact and successScience Festival Alliance (SFA) (2012) Get inspired A first look atscience festivals Retrieved from httpsciencefestivalsorgnews_itemget-inspired

Author(s) Whitney Cobb Sanlyn Buxner Stephanie ShippInstitution(s) 1 Lunar and Planetary Institute 2 McRELInternational 3 Planetary Science Institute

21910 ndash Lessons from a Train-the-TrainerProfessional Development Program The SustainableTrainer Engagement Program (STEP)The Sustainable Trainer Engagement Program (STEP) is amodified train-the-trainer professional development programbeing conducted by the Lunar and Planetary Institute (LPI) STEPhas provided two cohorts of 6-8th grade science specialists and leadteachers in the Houston region with in-depth Earth and SpaceScience (ESS) content activities and pedagogy over 15 days eachaligned with Texas science standards This project has twoover-arching goals to improve middle school ESS instruction andto create and test an innovative model for Train-the-TrainerThis poster will share details regarding STEPrsquos activities andresources program achievements and its main findings to dateSTEP is being evaluated by external evaluators at the ResearchInstitute of Texas part of the Harris County Department ofEducation External evaluation shows an increase after one year inSTEP participantsrsquo knowledge (cohort 1 showed a 10 increasecohort 2 showed a 20 increase) confidence in teaching Earth andSpace Science effectively (cohort 1 demonstrated a 10 increasecohort 2 showed a 20 increase) and confidence in preparingother teachers (cohort 1 demonstrated a 12 increase cohort 2showed a 20 increase) By September 2015 STEP participants led(or assisted in leading) approximately 40 workshops for about1800 science teachers in Texas Surveys of teachers attendingprofessional development conducted by STEP participants showvery positive responses with averages for conference workshopevaluations ranging from 36 on a 4 point scale and otherevaluations averaging from 41 to 50 on a 5 point scaleMain lessons for the team on the train-the-trainer model include alack of confidence by leaders in K-12 science education inpresenting ESS professional development difficulties in arrangingfor school or district content-specific professional development theminimal duration of most school and district professionaldevelopment sessions and uncertainties in partnerships betweenscientists and educators

Author(s) Christine Shupla Alicia Gladney HeatherDalton Keliann LaConte Jeannette Truxillo Stephanie ShippInstitution(s) 1 Harris County Department of Education 2Lunar and Planetary Institute

21911 ndash Inexpensive DAQ based physics labsQuality Data Acquisition (DAQ) based physics labs can be designed

using microcontrollers and very low cost sensors with minimal labequipment A prototype device with several sensors anddocumentation for a number of DAQ-based labs is showcased Thedevice connects to a computer through Bluetooth and uses asimple interface to control the DAQ and display real time graphsstoring the data in txt and xls formats A full device including alarger number of sensors combined with software interface anddetailed documentation would provide a high quality physics labeducation for minimal cost for instance in high schools lacking labequipment or students taking online classes An entire semesterrsquoslab course could be conducted using a single device with amanufacturing cost of under $20

Author(s) Benjamin Lewis Shane ClarkInstitution(s) 1 Mississippi State University

21912 ndash Assessment of Impact on Students andTeachers of Student-led inquiry-based planetaryscience instruction in Grades 3-8The University of Houston is in the process of developing a flexibleprogram that offers children an in-depth educational experienceculminating in the design and construction of their own modelMars rover The program is called the Mars Rover ModelCelebration (MRC) It focuses on students teachers and parents ingrades 3-8 Students design and build a model of a Mars rover tocarry out a student selected science mission on the surface of MarsA total of 195 Mars Rover teachers from the 2012-2013 2013-2014and 2014-2015 cohorts were invited to complete the Mars RoverTeacher Evaluation Survey The survey was administered onlineand could be taken at the convenience of the participant So far ~90teachers have participated with responses still coming in A total of1300 students from the 2013-2014 and 2014-2015 cohort wereinvited to submit brief self-assessments of their participation in theprogram Teachers were asked to rate their current level ofconfidence in their ability to teach specific topics within the Earthand Life Science realms as well as their confidence in their abilityto implement teaching strategies with their students The moststriking increase in this area was the reported 48 of teachers whofelt their confidence in teaching ldquoEarth and the solar system anduniverserdquo increased ldquoQuite a bitrdquo as a result of their participation inthe MRC program The vast majority of teachers (86-100) feltsomewhat to very confident in their ability to effectively implementall of the listed teaching strategies The most striking increaseswere the percentage of teachers who felt their confidence increasedldquoQuite a bitrdquo as a result of their participation in the MRC program inthe following areas ldquoGetting students interested in and curiousabout sciencerdquo (63) ldquoTeaching science as a co-inquirer withstudentsrdquo (56) and ldquoContinually find better ways to teachsciencerdquo (59) Student outcome analysis is pending correlationwith final progress reports for the participating students A keyfinding is that 354365 responding students in the 2014-2015cohort report substantial increase in science excitement owing toparticipation in the program

Author(s) Edgar Andrew Bering Coleen Carlson KennethNieser Elana SlagleInstitution(s) 1 Starfish Education 2 University of Houston

21913 ndash PUMAS The On-line journal of Math andScience Examples for Pre-College EducationPUMAS ndash ldquoPractical Uses of Math And Sciencerdquo ndash is an on-linecollection of brief examples showing how math and science topicstaught in K-12 classes can be used in interesting settings includingevery day life The examples are written primarily by scientistsengineers and other content experts having practical experiencewith the material They are aimed mainly at classroom teachers toenrich their presentation of math and science topics The goal ofPUMAS is to capture for the benefit of pre-college education theflavor of the vast experience that working scientists have withinteresting and practical uses of math and science There arecurrently over 80 examples in the PUMAS collection and they areorganized by curriculum topics and tagged with relevant gradelevels and curriculum topic benchmarks The published examplescover a wide range of subject matter from demonstrating why

2 3 1

2 12 2 1 2

1 1

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70

summer is hot to describing the fluid dynamics of a lava lamp tocalculating the best age to collect Social Security Benefits Theexamples are available to all interested parties via the PUMAS website httppumasnasagovWe invite the community to participate in the PUMAS collectionWe seek scientists and scientific thinkers to provide innovativeexamples of practical uses for teachers to use to enrich theclassroom experience and content experts to participate inpeer-review We also seek teachers to review examples fororiginality accuracy of content clarity of presentation andgrade-level appropriateness Finally we encourage teachers tomine this rich repository for real-world examples to demonstratethe value of math in science in everyday life

Author(s) Melissa G Trainer Ralph A KahnInstitution(s) 1 NASA Goddard Space Flight Center

21914 ndash DPS Planetary Science Graduate ProgramsListing A Resource for Students and AdvisorsWe began a web page on the DPS Education site in 2013 listing allthe graduate programs we could find that can lead to a PhD with aplanetary science focus Since then the static page has evolved intoa database-driven filtered-search site It is intended to be a usefulresource for both undergraduate students and undergraduateadvisers allowing them to find and compare programs across abasic set of search criteria From the filtered list users can click onlinks to get a quick look at the database information and followlinks to the program main siteThe reason for such a list is because planetary science is a headingthat covers an extremely diverse set of disciplines The usual case isthat planetary scientists are housed in a discipline-placeddepartment so that finding them is typically noteasymdashundergraduates cannot look for a Planetary Sciencedepartment but must (somehow) know to search for them in alltheir possible places This can overwhelm even determinedundergraduate student and even many advisersWe present here the updated site and a walk-through of the basicfeatures In addition we ask for community feedback on additionalfeatures to make the system more usable for them Finally we callupon those mentoring and advising undergraduates to use thisresource and program admission chairs to continue to review theirentry and provide us with the most up-to-date informationThe URL for our site is httpdpsaasorgeducationgraduate-schools

Author(s) David R Klassen Anthony Roman BonnieMeinkeInstitution(s) 1 Rowan Univ 2 Space Telescope ScienceInstitute

21915 ndash A Guide for Scientists Interested inResearching Student OutcomesScientists spend years training in their scientific discipline and arewell versed the literature methods and innovations in their ownfield Many scientists also take on teaching responsibilities withlittle formal training in how to implement their courses or assesstheir students There is a growing body of literature of whatstudents know in space science courses and the types ofinnovations that can work to increase student learning butscientists rarely have exposure to this body of literature Forscientists who are interested in more effectively understandingwhat their students know or investigating the impact their courseshave on students there is little guidance Undertaking a moreformal study of students poses more complexities including findingrobust instruments and employing appropriate data analysisAdditionally formal research with students involves issues ofprivacy and human subjects concerns both regulated by federallawsThis poster details the important decisions and issues to considerfor both course evaluation and more formal research using acourse developed facilitated evaluated and researched by a hybridteam of scientists and science education researchers HabWorldsdesigned and implemented by a team of scientists and faculty atArizona State University has been using student data to

continually improve the course as well as conduct formal researchon studentsrsquo knowledge and attitudes in science This ongoingproject has had external funding sources to allow robustassessment not available to most instructors This is a case studyfor discussing issues that are applicable to designing and assessingall science courses Over the course of several years instructorshave refined course outcomes and learning objectives that areshared with students as a roadmap of instruction The team hassearched for appropriate tools for assessing student learning andattitudes tested them and decided which have worked or not forassessment in the course Data from this assessment has led tomany changes in the course to better meet the course goals Wewill share challenges and lessons learned in our project to assistother instructors interested in doing research on studentoutcomes

Author(s) Sanlyn R Buxner Ariel Anbar Steve Semken Chris Mead Lev Horodyskyj Viranga Perera Geoffrey Bruce David SchoumlnsteinInstitution(s) 1 Arizona State University 2 Smart Sparrow 3University of Arizona

21916 ndash Small Worlds Week An online celebration ofplanetary science using social media to reach millionsIn celebration of the many recent discoveries from New HorizonsDawn Rosetta and Cassini NASA launched Small Worlds Weekan online social media driven outreach program leveraging theinfrastructure of Sun-Earth Days that included a robust webdesign exemplary education materials hands-on fun activitiesmultimedia resources science and career highlights and aculminating social media event Each day from July 6-9 a newclass of solar system small worlds was featured on the websiteMonday-comets Tuesday-asteroids Wednesday-icy moons andThursday-dwarf planets Then on Friday July 10 nine scientistsfrom Goddard Space Flight Center Jet Propulsion LaboratoryNaval Research Laboratory and Lunar and Planetary Institutegathered online for four hours to answer questions from the publicvia Facebook and Twitter Throughout the afternoon the scientistsworked closely with a social media expert and several summerinterns to reply to inquirers and to archive their chats By allaccounts Small Worlds Week was a huge success with 37 millionpotential views of the social media QampA posts The group plans toimprove and replicate the program during the school year with amore classroom focus and then to build and extend the program tobe held every year For more information visit httpsunearthdaynasagov or catch us on Twitter nasasww

Author(s) Louis MayoInstitution(s) 1 NASAs GSFC

21917 ndash Travelers In The Night in the Old and NewMediaTravelers in the Night is a series of 2 minute audio programsbased on current research in astronomy and the space sciencesAfter more than a year of submitting ldquoTravelers In The Nightrdquo 2minute audio pieces to NPR and Community Radio stations withlimited success a parallel effort was initiated by posting the piecesas audio podcasts on Spreakercom and iTunesThe classic media dispenses programming whose content andschedule is determined by editors and station managers Riding thewave of new technology people from every demographic groupacross the globe are selecting what when and how they receiveinformation and entertainment This change is significant with thePew Research Center reporting that currently more than 60 ofFacebook and Twitter users now get their news andor links tostories from these sources What remains constant is the publicrsquosinterest in astronomy and spaceThis poster presents relevant statistics and a discussion of theinitial results of these two parallel efforts

Author(s) Albert D GrauerInstitution(s) 1 University of Arizona

21918 ndash Helping students understand planet

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2

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71

categories using sensing personification Jupiter aswant-to-be star Earth as want-to-be Jupiter etcStudents often in learning about the classification of planetsconsider the planets to be in strict categories (such as gas giantsand terrestrial planets) and assume that these categories aredrastically different in nature This is not the case Small objectssuch as asteroids have a weak gravitational pull such that theycannot hold an atmosphere while terrestrial planets are capable ofholding a gaseous (often transparent) atmosphere according totheir larger mass However asteroids and terrestrial planets arevery similar in composition (though not necessarily inhomogeneity due to varying presence of collisional heating duringformation) Meanwhile gas giant planets (also often referred to asJovian planets) such as Jupiter have been theorized to containsuper-sized rocky terrestrial-like planets interior to their densecloud covering Hence due then to their similar natures thecategorization of the terrestrial and gas giant planets is made notdue to fundamental differences in the nature of the planets aconcept often ill-understood by students Examining this furtherthe gas giants are planets whose masses and hence gravitationalability to condense their gases especially those close to their coreis less than those of stars wherein thermonuclear fusion initiatesThis implies that stars also have terrestrial cores (albeit likelyextremely densely packed) but the gaseous environments ofhydrogen are dense enough to start and sustain this process ofthermonuclear fusion It is proposed here that seeing planets asfundamentally related to each other in composition thoughdiffering in size allows students to better understand the variety ofplanet types AND describing these as want-to-be (or wanna-be) interms of ranking and according to a ldquosensingrdquo personification thateschews anthropomorphism animism or teleology [see A ETabor-Morris ldquoThinking in terms of sensors personification of selfas an object in physics problem solvingrdquo Physics Education 502(Feb 2015) 203-209] to assist in putting this into perspective forstudents

Author(s) Anne Tabor-MorrisInstitution(s) 1 Georgian Court University

21919 ndash New Horizons at Pluto An Overview ofEducational Activities Outreach at Fernbank ScienceCenter Atlanta Georgia (USA)We report on educational activities and associated outreach atFernbank Science Center (Atlanta GA) in conjunction with theJuly 2015 New Horizons spacecraft encounter at Pluto Onencounter day a public lecture about the dwarf planet waspresented by Georgiarsquos NASA Solar System ambassador to kick offthe arrival of the space probe at Pluto In the months following theflyby we presented a program called ldquoExploring New Horizonsrdquo inthe Science Centerrsquos Zeiss planetarium This program is a digitalfull-dome presentation about the discovery of Pluto and itssubsequent exploration ndash including an overview of the NewHorizons mission Since NASA continues to receive data from theprobe a brief update (tribute) is included at the end of eachplanetarium program that features the latest imagery and data fromthe dwarf planet We anticipate running the planetarium programthroughout the fall semester of 2015 With Pluto visible in the earlyevening autumn sky observations are possible with Centerrsquos 09 mtelescope which is open for public viewing on clear Thursday andFriday nights following the planetarium program Although Pluto issomewhat faint through the telescopes eyepiece it is visible andclearly identified within the surrounding starfield Intermittentpost-encounter lectures (Messages from the Outer Solar System)have been given on Friday evenings as well Finally due to thecontinued interest in Pluto we have developed a new outreachprogram about dwarf planets in general geared towards 4 ndash 6students

Author(s) Edward F Albin R Scott HarrisInstitution(s) 1 Fernbank Science Center

21920 ndash Partnering to Enhance Planetary ScienceEducation and Public Outreach ProgramThe Lunar and Planetary Institute (LPI) in Houston Texas utilizes

many partners to support its multi-faceted Education and PublicOutreach (EPO) program The poster will share what we havelearned about successful partnerships One portion of the programis focused on providing training and NASA content and resourcesto K-12 educators Teacher workshops are performed in severallocations per year including LPI and the Harris CountyDepartment of Education as well as across the country incooperation with other programs and NASA Planetary SciencemissionsTo serve the public LPI holds several public events per year calledSky Fest featuring activities for children telescopes for night skyviewing and a short scientist lecture For Sky Fest LPI partnerswith the NASA Johnson Space Center Astronomical Society theyprovide the telescopes and interact with members of the public asthey are viewing celestial objects International Observe the MoonNight (InOMN) is held annually and involves the same aspects asSky Fest but also includes partners from Johnson Space CenterrsquosAstromaterials Research and Exploration Science group whoprovide Apollo samples for the eventAnother audience that LPI EPO serves is the NASA PlanetaryScience EPO community Partnering efforts for the EPOcommunity include providing subject matter experts forprofessional development workshops and webinars connections togroups that work with diverse and underserved audiences andavenues to collaborate with groups such as the National ParkService and the Afterschool AllianceAdditional information about LPIrsquos EPO programs can be found athttpwwwlpiusraedueducation View a list of LPI EPOrsquospartners here httpwwwlpiusraedueducationpartners

Author(s) Heather Dalton Stephanie Shipp ChristineShupla Andrew Shaner Keliann LaConteInstitution(s) 1 Lunar and Planetary Institute

21921 ndash Contextual Student Learning throughAuthentic Asteroid Research Projects using a RoboticTelescope NetworkSkynet is a worldwide robotic telescope network operated by theUniversity of North Carolina at Chapel Hill with active observingsites on 3 continents The queue-based observation request systemis simple enough to be used by middle school students butpowerful enough to supply data for research scientists The SkynetJunior Scholars program funded by the NSF has teamed up withprofessional astronomers to engage students from middle school toundergraduates in authentic research projects from targetselection through image analysis and publication of resultsAsteroid research is a particularly fruitful area for youthcollaboration that reinforces STEM education standards and canallow students to make real contributions to scientific knowledgeeg orbit refinement through astrometric submissions to theMinor Planet Center We have created a set of projects for youth to1 Image an asteroid make a movie and post it to a gallery 2Measure the asteroidrsquos apparent motion using the Afterglow onlineimage processor and 3 Image asteroids from two or moretelescopes simultaneously to demonstrate parallax The apparentmotion and parallax projects allow students to estimate thedistance to their asteroid as if they were the discoverer of a brandnew object in the solar system Older students may take onadvanced projects such as analyzing uncertainties in asteroidorbital parameters studying impact probabilities of known objectsobserving time-sensitive targets such as Near Earth Asteroids andeven discovering brand new objects in the solar systemImages are acquired from among seven Skynet telescopes in NorthCarolina California Wisconsin Canada Australia and Chile aswell as collaborating observatories such as WestRock in ColumbusGeorgia Stone Edge in El Verano California and AstronomicalResearch Institute in Westfield Illinois

1

th th

1 1

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72

Author(s) Vivian L Hoette Andrew W Puckett Tyler RLinder Sue Ann Heatherly Travis A Rector Joshua BHaislip Kate Meredith Austin L Caughey Johnny E Brown Cameron B McCarty Kevin T WhitmoreInstitution(s) 1 Astronomical Research Institute 2 ColumbusState University 3 National Radio Astronomy Observatory 4University of Alaska Anchorage 5 University of Chicago 6University of North Carolina at Chapel Hill

21922 ndash Spatial Reasoning Training Through LightCurves Of Model AsteroidsRecent research has demonstrated that spatial reasoning skillslong known to be crucial to math and science success areteachable Even short stints of training can improve spatialreasoning skills among students who lack them (Sorby et al2006) Teaching spatial reasoning is particularly valuable towomen and minorities who through societal pressure often doubttheir spatial reasoning skill (Hill et al 2010) We have designed ahands on asteroid rotation lab that provides practice in spatialreasoning tasks while building the studentrsquos understanding ofphotometry For our tool we mount a model asteroid with anyshape of our choosing on a slowly rotating motor shaft whosespeed is controlled by the experimenter To mimic an asteroid lightcurve we place the model asteroid in a dark box shine a movablelight source upon our asteroid and record the light reflected onto amoveable camera Students may then observe changes in the lightcurve that result from varying a) the speed of rotation b) the modelasteroidrsquos orientation with respect to the motor axis c) the modelasteroidrsquos shape or albedo and d) the phase angle After practicingwith our tool students are asked to pair new objects to theircorresponding light curves To correctly pair objects to their lightcurves students must imagine how light scattering off of a threedimensional rotating object is imaged on a ccd sensor plane andthen reduced to a series of points on a light curve plot Through theuse of our model asteroid the student develops confidence inspatial reasoning skills

Author(s) Julie Ziffer Paul A Nakroshis Benjamin TRudnick Maxwell J Brautigam Tyler W NelsonInstitution(s) 1 Falmouth High School 2 University ofSouthern Maine

21923 ndash 3-D Printed Asteroids for OutreachAstronomy Education3-D printed asteroids provide new opportunities for outreachastronomy education due to their low cost interactive potentialand high interest value Telescopes are expensive bulky fragileand cannot be used effectively during the day 3-D printing ofasteroids combines exciting new technology with astronomyappealing to a broader audience The printed models arescientifically accurate as their shapes have been modeled usinglight-curve inversion techniques using and occultation data toprovide a jumping off point for discussions of these advanced andexciting topics

Author(s) April RussellInstitution(s) 1 Siena College

21924 ndash An Update on the NASA Planetary ScienceDivision Research and Analysis ProgramIntroduction NASArsquos Planetary Science Division (PSD) solicitsits research and analysis (RampA) programs each year in ResearchOpportunities in Space and Earth Sciences (ROSES) Beginningwith the 2014 ROSES solicitation PSD changed the structure of theprogram elements under which the majority of planetary scienceRampA is done Major changes included the creation of five coreresearch program elements aligned with PSDrsquos strategic sciencequestions the introduction of several new RampA opportunities newsubmission requirements and a new timeline for proposalsubmissionROSES and NSPIRES ROSES contains the researchannouncements for all of SMD Submission of ROSES proposals isdone electronically via NSPIRES httpnspiresnasaprscom Wewill present further details on the proposal submission process to

help guide younger scientists Statistical trends including theaverage award size within the PSD programs selections rates andlessons learned will be presented Information on new programswill also be presented if availableReview Process and Volunteering The SARA website(httpsaranasagov) contains information on all ROSESsolicitations There is an email address (SARAnasagov) forinquiries and an area for volunteer reviewers to sign up The peerreview process is based on ScientificTechnical Merit Relevanceand Level of Effort and will be detailed within this presentationROSES 2015 submission changes All PSD programs willcontinue to use a two-step proposal submission process A Step-1proposal is required and must be submitted electronically by theStep-1 due date The Step-1 proposal should include a descriptionof the science goals and objectives to be addressed by the proposala brief description of the methodology to be used to address thescience goals and objectives and the relevance of the proposedresearch to the call submitted to

Author(s) Max Bernstein Christina Richey Jonathan RallInstitution(s) 1 NASA HQ

21925 ndash Astronomy Education amp Outreach in SouthAfricaAlthough South Africa has evolved greatly in the 20 years since theend of apartheid it remains a very divided country The highest-performing students are comparable in ability to those in the USand Europe but nearly all of these students are from privelegedAfrikaaner (European) backgrounds The vast majority of studentsin the country are native African and school standards remain verylow across the country It is common that students have notextbooks teachers have only a high school education and schoolshave no telephones and no toilets By high school graduation themajority of students have never used a web browser -- evenstudents in the capital of Johannesburg And while a few studentsare inspired by home-grown world-class projects such as theSquare Kilometer Array (SKA) and Southern African LargeTelescope (SALT) most remain unaware of their existenceDespite the poor state of education in the country students workhard are curious and desire information from the outside worldAstronomy is one subject in which students in rural Africa oftenshow exceptional interest Perhaps astronomy serves as a gatewayscience linking the physically observable world with the exotic andunknownHere I report on many visits I have made to both rural and urbanschools in South Africa during the 2013-2015 period I haveinteracted with thousands of grade 7-12 students at dozens ofschools as well as taught students who graduated from this systemand enrolled in local universities I will present an assessment ofthe state of science education in South Africa as well as a fewbroader suggestions for how scientists and educators in developedcountries can best make an impact in Southern Africa

Author(s) Henry B ThroopInstitution(s) 1 PSI

300 ndash Titans Atmosphere and Surface30001 ndash Monstrous Ice Cloud System in TitansPresent South Polar StratosphereDuring southern autumn when sunlight was still availableCassinis Imaging Science Subsystem discovered a cloud around300 km near Titans south pole (West R A et al AASDPSAbstracts 45 30503 2013) the cloud was later determined byCassinis Visible and InfraRed Mapping Spectrometer to containHCN ice (de Kok et al Nature 514 pp 65-67 2014) This cloudhas proven to be only the tip of an extensive ice cloud systemcontained in Titans south polar stratosphere as seen through thenight-vision goggles of Cassinis Composite InfraRed Spectrometer(CIRS) As the sun sets and the gloom of southern winterapproaches evidence is beginning to accumulate from CIRS far-IRspectra that a massive system of nitrile ice clouds is developing inTitans south polar stratosphere Even during the depths of

5 21 3 46 5 2 2

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northern winter nothing like the strength of this southern systemwas evident in corresponding north polar regionsFrom the long slant paths that are available from limb-viewingCIRS far-IR spectra we have the first definitive detection of the νband of cyanoacetylene (HC N) ice in Titanrsquos south polarstratosphere In addition we also see a strong blend of nitrile icelattice vibration features around 160 cm From these data we areable to derive ice abundances The most prominent (and stillchemically unidentified) ice emission feature the Haystack (at220 cm ) is also observed We establish the vertical distributionsof the ice cloud systems associated with both the 160 cm featureand the Haystack The ultimate aim is to refine the physical andpossibly the chemical relationships between the twoTransmittance thin film spectra of nitrile ice mixtures obtained inour Spectroscopy for Planetary ICes Environments (SPICE)laboratory are used to support these analyses

Author(s) Carrie Anderson Robert Samuelson JasonMcLain Richard Achterberg F Michael Flasar Stefanie MilamInstitution(s) 1 NASA GSFC 2 University of Maryland

30002 ndash Condensation of trace species to form icelayers in Titans stratosphereIn addition to the organic haze particles produced photochemicallyin Titans upper atmosphere a number of trace gases are alsocreated These hydrocarbon and nitrile species include C H C H C H HCN HC N C H CN and many more While bothVoyager and Cassini observations have found evidence for ices (egC N HCN) in the atmosphere above Titans poles these speciesare also likely to condense at other latitudes forming optically thinice layers in the stratosphere A series of simulations have beenconducted using Titan CARMA a 1-D microphysics and radiativetransfer model to explore cloud particle formation with ~20 ofTitans trace hydrocarbon and nitrile gases These species reachtheir condensation temperatures between 60 and 110 km Mostcondense solely as ices however C H will condense first near 70km as a liquid and then freeze as the droplets descend toward thesurface C H and C H join CH as a liquid at Titans surfaceMany ices have long condensation timescales resulting in particleradii ~1 μm or less Several (including HCN C H C H ) willgrow 10-50 times larger Expected condensation altitudes andparticle sizes will be presented as well as the implications for theoptical properties of Titans stratospheric aerosol particlesThis work was supported by the NASA Outer Planets Researchprogram

Author(s) Erika L BarthInstitution(s) 1 Southwest Research Inst

30003 ndash Wind Shear May Produce Long-Lived Stormsand Squall Lines on TitanThe impact of CAPE and wind shear on storms in a Titan-likeenvironment are explored through numerical simulationNumerical modeling indicates that both large-scale shear andCAPE environment control the dynamics of the clouds Thisresponse to the large-scale environment is analogous to thebehavior of deep convective clouds on Earth The balance betweenshear and CAPE as expressed through the bulk RichardsonNumber (N ) is a good indicator of the response of a storm to itsenvironment Large N results in short-lived single cell storms(Figure 1) As shear increases for a given CAPE and N decreasesthe storms transition to a multicellular regime Multicellularstorms are longer-lived and are characterized by a downdraftgenerated cold pool that interacts with the background shearvorticity to initiate cells along the leading edge of the storm gustfront (Figure 2) Very long-lived storms (gt24 hours) propagatingfor 1000 km or more might be possible The most intensemulticellular systems simulated in this study behave similar toterrestrial squall lines and very long-lived storms (gt24 hours)propagating for 1000 km or more might be possible Cloudoutbursts and linear cloud features observed from ground andCassini may be the result of these organized storm systemsVarying amounts of shear in the Titan environment might explainthe variety of convective cloud expressions identified in Cassini

orbiter and ground-based observations The resulting distributionand magnitude of precipitation as well as surface winds associatedwith storms have implications on the formation of fluvial andaeolian features including dunes and on the exchange of methanewith the surface and lakes

Author(s) Scot CR Rafkin Erika BarthInstitution(s) 1 SWRI

30004 ndash Asymmetric lake distribution on Titanmediated by methane transport due to atmosphericeddiesThe observed north-south asymmetry in the distribution of Titansseas and lakes has been proposed to be a consequence of orbitalforcing affecting Titans hydrologic cycle as in the present thenorthern summer is longer but milder than its southerncounterpart Though recent general circulation models havesimulated asymmetrical surface liquid distributions themechanism that generates this asymmetry has not been explainedIn this work we compare axisymmetric and three-dimensionalsimulations of Titans atmospheric circulation with the TitanAtmospheric Model (TAM) [Lora et al 2015 Icarus 250] toinvestigate the transport of moisture by the atmosphere Asignificant hemispheric asymmetry only develops in the latter caseand we demonstrate that equatorward transport by high-latitudebaroclinic eddies is responsible Eddies transport moisture fromthe high latitudes into the low and midlatitude cross-equatorialmean meridional circulation producing an atmospheric bucketbrigade The moisture transport by eddies is more intense in thesouth than in the north as a consequence of the orbital forcing andtherefore the result is net northward transport of methaneexplaining the surface buildup in the north

Author(s) Juan M Lora Jonathan L MitchellInstitution(s) 1 University of California

30005 ndash Seasonal Surface Temperature Changes onTitanThe Composite Infrared Spectrometer (CIRS) on Cassini has beenmeasuring surface brightness temperatures on Titan since 2004(Jennings et al 2011 Cottini et al 2012 Tan et al 2015) Radiationfrom the surface reaches space through a window of minimumopacity in Titanrsquos atmosphere near 19 microns wavelength Wemapped surface temperatures in five time periods each about 2years centered on solar longitudes Ls = 313deg 335deg 0deg 28deg and 53degdegrees Using zonally-averaged spectra binned in 10-degreelatitude intervals we clearly see the seasonal progression of thepole-to-pole temperature distribution Whereas peak temperaturesin the vicinity of the Equator have been close to 94 K throughoutthe Cassini mission early in the mission temperatures at the NorthPole were as low as 90 K and at the South Pole were 92 K Late inthe mission the pattern has reversed 92 K in the north and 90 K inthe south Over 2005 to 2014 the peak temperature moved inlatitude from about 15 S to 15 N We estimate a seasonal lag of 02Titan month In 2010 the temperature distribution wasapproximately symmetric north and south agreeing with Voyager 1from one Titan year earlier The surface temperatures followclosely the predictions of Tokano (2005) Our measurements mayindicate a lower thermal inertia in the south than in the northJennings DE et al ApJ Lett 737 L15 (2011)Cottini V et al 2012 Planet Space Sci 60 62 (2012)Tan S P et al Icarus 250 64 (2015)Tokano T Icarus 204 619 (2005)

Author(s) Donald E Jennings Valeria Cottini Conor ANixon Athena Coustenis Tetsuya TokanoInstitution(s) 1 Department of Astronomy University ofMaryland 2 LESIA Paris Obs PSL-Research Univ CNRS UnivParis 06 Sorbonne Univ Univ Paris-Diderot 3 NASA GoddardSpace Flight Center 4 Universitaumlt zu Koumlln

30006 ndash Titanrsquos mid-latitude surface regions withCassini VIMS and RADARThe Cassini-Huygens mission instruments have revealed Titan to

63

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4 2

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3 8 2 2

1

RR

R

1 1

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3 13 2 4

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have a complex and dynamic atmosphere and surface Data fromthe remote sensing instruments have shown the presence ofdiverse surface terrains in terms of morphology and compositionsuggesting both exogenic and endogenic processes [1] We defineboth the surface and atmospheric contributions in the VIMSspectro-imaging data by use of a radiative transfer code in thenear-IR range [2] To complement this dataset the Cassini RADARinstrument provides additional information on the surfacemorphology from which valuable geological interpretations can beobtained [3] We examine the origin of key Titan terrains coveringthe mid-latitude zones extending from 50ordmN to 50ordmS The differentgeological terrains we investigate include mountains plainslabyrinths craters dune fields and possible cryovolcanic andorevaporite features We have found that the labyrinth terrains andthe undifferentiated plains seem to consist of a very similar if notthe same material while the different types of plains showcompositional variations [3] The processes most likely linked totheir formation are aeolian fluvial sedimentary lacustrine inaddition to the deposition of atmospheric products though theprocess of photolysis and sedimentation of organics We show thattemporal variations of surface albedo exist for two of the candidatecryovolcanic regions The surface albedo variations together withthe presence of volcanic-like morphological features suggest thatthe active regions are possibly related to the deep interior possiblyvia cryovolcanism processes (with important implications for thesatellitersquos astrobiological potential) as also indicated by new interiorstructure models of Titan and corresponding calculations of thespatial pattern of maximum tidal stresses [4] However anexplanation attributed to exogenic processes is also possible [5]We will report on results from our most recent research on thesurface properties of Titan[1] Solomonidou et al Icarus accepted [2] Solomonidou et al JGR119 1729ndash1747 2014 [3] Lopes et al Icarus in rev [4] Sohl et alJGR 119 1013-1036 2014 [5] Moore amp Pappalardo Icarus 212790-806 2011

Author(s) Anezina Solomonidou Rosaly MC Lopes Athena Coustenis Michael Malaska Sebastien Rodriguez Luca Maltagliati Pierre Drossart Michael Janssen KennethLawrence Ralf Jaumann Frank Sohl Katrin Stephan RobertH Brown Emmanuel Bratsolis Christos MatsoukasInstitution(s) 1 Department of Physics National andKapodistrian University of Athens 2 DLR Institute of PlanetaryResearch 3 Laboratoire AIM Universiteacute Paris Diderot Paris7CNRSCEA-Saclay DSMIRFUSAp 4 LESIA - Observatoire deParis CNRS UPMC Univ Paris 06 Univ Paris-Diderot 5 Lunarand Planetary Laboratory University of Arizona 6 NASA JetPropulsion Laboratory California Institute of Technology

30007 ndash Using the VIMS Dataset to UnderstandTitanrsquos Hydrologic Cycle Through CloudCharacterizationAlong with Earth Titan is the only body in our Solar System topossess an active hydrologic cycle Monitoring how Titanrsquosmethane-based hydrologic cycle varies with season over Saturnrsquos297-year orbital period is essential for understanding its climatesystemUsing a newly developed radiative transfer pipeline with updatedHITRAN methane line parameters we will present an ongoinganalysis of the known cloud observations in the VIMS datasetAlthough much work has gone into finding clouds in this datasetlittle work has been done on understanding the characteristics ofthese clouds barring a handful of individual analyses Our pipelineallows for fast determination of these cloud characteristicsincluding optical depth altitude and mean drop size VIMS offerstwo advantages providing consecutive observations of individualcloud systems to help diagnose formation mechanism andproviding a decade long dataset to track seasonal variations likethose observed in cloud frequency and location Characterizingclouds allows for an understanding of seasonally varying formationmechanisms traces Titanrsquos atmospheric methane content acrossseasonal timescales and can indicate clouds that could potentiallyhave precipitated to provide context for interpreting observedsurface features

We will also present an update on an ongoing ground based- cloudmonitoring campaign This campaign begun in April 2014 has(nearly) continually monitored Titan on a variety of telescopes forthe past 15 years To date no cloud activity has been observeddespite the variety in observation techniques that multipletelescopes allow This is interesting because large cloud outburstswere observed during the equivalent point in southern summerand suggest a dichotomy in the seasonal dynamics of Titanrsquosatmosphere Understanding when and with what frequency cloudsbegin to form in the north is crucial to understanding Titanrsquoshydrologic cycle on seasonal time scales

Author(s) Paul Corlies Alexander G Hayes SebastienRodriguez Mate Adamkovics Patricio Rojo Elizabeth PTurtleInstitution(s) 1 Cornell University 2 John Hopkins UnivApplied Physics Laboratory 3 Universidad de Chile 4 UniversiteParis Diderot - Paris 7 5 University of California Berkeley

30008 ndash Hydrology-based understanding of OntarioLacus in Titans south poleOntario Lacus is the largest presently filled lake at the south pole ofTitan Many other large basins in south pole exist at lowerelevations than Ontario Lacus but are currently empty To find outwhat sets Ontario apart from those empty basins we have carried adetailed hydrological assessment of Ontario Lacus Topography ofthe region as derived from Cassini RADAR altimetry was used todetermine the catchment area of Ontario Lacus We could map theareal extent of catchments as far as southern mid-latitudes Cloudsin southern mid and high latitudes have been observed by CassiniVIMS which indicate possible precipitation in those regionsPrecipitation in southern mid-latitudes coupled with the largecatchment areas of Ontario Lacus could be the reason behind itbeing filled Our mass conservation calculations indicate that ifrunoff was the only contributor to the lake volume then the lakemight be filled within one Titan year (295 Earth years) in entiretyWe also observe a non-linear relationship between the longestidentifiable stream and the catchment area (Hacks Law) which isconsistent with terrestrial hydrological systems and may help infurther interpretation of the hydrology of Ontario Lacus

Author(s) Rajani D Dhingra Jason W Barnes Brian JYanites Randolph L KirkInstitution(s) 1 Astrogeology Science Center United StatesGeological Survey 2 University of Idaho

30009 ndash Near Infrared Spectroscopy of LiquidHydrocarbon Mixtures for Understanding theComposition of Titanrsquos LakesThe presence of ethane and methane lakes on Titan was confirmedby the Cassini Visible and Infrared Mapping Spectrometer (VIMS)data in 2008 and has been investigated in further detail by theCassini radar instrument (Brown et al 2008 Pailloue et al 2008)Modeled compositions suggest that the lakes are predominantlyliquid ethane with liquid methane propane and butane howeverpure liquid methane lakes (such as Ligeia Mare) may also bepresent (Cordier et al 2009 Mastrogiuseppe et al 2014) Wepresent a proof-of-concept instrument consisting of a nearinfrared (NIR) spectrometer with a fiber optic probe in order toconduct non-invasive analyses of cryogenic fluids on planetarybodies To determine the utility of spectroscopy for in-situ studieswe collected transmission spectra of hydrocarbon mixtures puremethane and ethane endmembers and nitrogen-saturatedhydrocarbons in the NIR region between 900 to 2500 nm liquidhydrocarbons were measured in a dewar filled with liquid nitrogencontained within a glove bag pumped with gaseous nitrogen at atotal oxygen concentration of lt 01 The resultant spectracontained key absorption features that allowed us to determine therelative abundances of each endmember and the effectstemperature and dissolved nitrogen based on the changes in peakintensity Peak intensity as well as integrated absorbancefull-width half-maximum and peak location were calculated usinga multi-peak fitting algorithm we also adopted a simple linearmixing model which used pure ethane and methane spectra as well

6 64 6 3

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2

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75

as the measured mixtures to calculate the linear coefficients ofeach endmember within the mixture Resultant plots of changes inpeak intensity with temperature (for methane) peak intensity withmole fraction of methane (or ethane) and comparisons of themodeled linear coefficients with the mole fraction of methane (orethane) added will yield useful data on how methane ethane anddissolved nitrogen mix Ideally this information can also be used tobetter validate theoretical models on hydrocarbon mixing andnitrogen solubility providing insight on the loss tangentmeasurements of Titanrsquos lakes obtained by Mastrogiuseppe fromradar altimetry data

Author(s) Bryne Hadnott Robert Hodyss Morgan Cable Tuan Vu Alexander HayesInstitution(s) 1 Cornell University 2 Jet PropulsionLaboratory

301 ndash Asteroid Surveys See and Say30101 ndash NEOWISE Reactivation Mission Year OnePreliminary Asteroid Diameters and AlbedosThe infrared NEOWISE project (Mainzer et al 2011a) hasmeasured diameters and albedos for sim20 of the known asteroidpopulation the majority of these measurements to date (Mainzeret al 2011b 2012 2015 Masiero et al 2011 2012 Grav et al 20112012a Bauer et al 2013) Here we expand the number of asteroidscharacterized by NEOWISE deriving diameters and albedos for7959 asteroids detected between December 13 2013 andDecember 13 2014 during the first year of the Reactivationmission 7758 are Main Belt or Mars-crossing asteroids 17 ofthese objects have not been previously characterized using WISEor NEOWISE thermal measurements Diameters are determined toan accuracy of ~20 or better If good-quality H magnitudes areavailable albedos can be determined to within ~40 or better

Author(s) Carolyn Nugent A Mainzer J R Masiero JBauer R M Cutri T Grav E Kramer S Sonnett RStevenson E WrightInstitution(s) 1 CaltechIPAC 2 JPL 3 Planetary ScienceInstitute 4 Self 5 UCLA

30102 ndash NEOSurvey An Spitzer Exploration ScienceSurvey of Near Earth Object PropertiesWe are carrying out a Spitzer Cycle 11 (2015-2016) ExplorationScience program entitled NEOSurvey in which we are observing597 known Near Earth Objects (NEOs) in 710 hours of observingtime Each object is observed at 45 microns The primary goal ofour program is to use a thermal model to create a catalog of NEOdiameters and albedos that can be used for a wide range of sciencegoals From this catalog we will derive the size distribution of NEOsdown to 100 meters and measure the compositional distribution ofNEOs as a function of size We include in our target list only objectsthat are too faint to be detected by NEOWISE This catalog istherefore highly complementary to existing and forthcomingsamples and will complete a database of diameters and albedos fornearly 2000 NEOs (including results from our previous Spitzerprogram ExploreNEOs as well as objects observed by NEOWISE)We will present the status of the program and results to date somenine months into the execution of the program All observationaland model results are published immediately online atnearearthobjectsnauedu Support for this work is provided by theSpitzer Science Center

Author(s) David E Trilling Michael Mommert JosephHora Steve Chesley Joshua Emery Giovanni Fazio AlanHarris Michael Mueller Howard SmithInstitution(s) 1 German Aerospace Centre (DLR) 2 Harvard-Smithsonian Center for Astrophysics 3 NASAJPL 4 NetherlandsInstitute for Space Research 5 Northern Arizona University 6 UTennessee Knoxville

30103 ndash Main-Belt Source Regions for PotentiallyHazardous Near-Earth Asteroids and Sample Return

TargetsSpectroscopic and taxonomic information is now available for morethan 1000 near-Earth objects (NEOs) thanks in large measure tothe NASA IRTF long-term NEO spectral reconnaissance programwe call the MIT-Hawaii Near-Earth Object Spectroscopic Survey(MITHNEOS) [1] This sample comprises about 10 of the totalNEO population including Potentially Hazardous Asteroids(PHAs) and finds that all defined main-belt asteroid classes arealso present within the near-Earth population Using this largestavailable NEO dataset and dynamic source region models (such as[2]) we will present new results on the provenance of PHAs sourceregions for each of the asteroid taxonomic classes and pinpointsources for major meteorite classes such as H L and LL ordinarychondrites In finding these correlations we find that source regionsignatures for B- C- and Cg-type NEOs include Jupiter familycomets further adding interest to the sampling of these classes byimpending missions [3 4] This work is supported by the NationalScience Foundation Grant 0907766 and NASA GrantNNX10AG27G[1] Tokunaga A et al (2006) BAAS 38 5907 [2] Bottke WF etal (2002) Icarus 156 399 [3] Lauretta D S et al (2015) MAPS50 834 [4] Abe M et al (2012) 39th COSPAR AbstractH02-7-12

Author(s) Richard P Binzel F E DeMeo B J Burt DPolishook T H Burbine N Moskovitz S J Bus ATokunaga M BirlanInstitution(s) 1 Lowell Observatory 2 MIT 3 ParisObservatory 4 University Hawaii

30104 ndash The Bias-Corrected Taxonomic Distributionof Mission-Accessible Small Near-Earth ObjectsAlthough they are thought to compose the majority of theNear-Earth object (NEO) population the small (d lt 1 km)near-Earth asteroids (NEAs) have not yet been studied asthoroughly as their larger cousins Sub-kilometer objects areamongst the most abundant newly discovered NEOs and are oftentargets of opportunity observable for only a few days to weeks aftertheir discovery Even at their brightest (V ~ 18) these asteroids arefaint enough that they must be observed with large ground-basedtelescopesThe Mission Accessible Near-Earth Object Survey (MANOS) beganin August 2013 as a multi-year physical characterization surveythat was awarded survey status by NOAO MANOS will targetseveral hundred mission-accessible NEOs across visible andnear-infrared wavelengths ultimately providing a comprehensivecatalog of physical properties (astrometry light curves spectra)Fifty-seven small mission-accessible NEAs were observed betweenmid 2013 and mid 2015 using GMOS at Gemini North amp Southobservatories as well as the DeVeny spectrograph at LowellObservatorys Discovery Channel Telescope Archival data of 43objects from the MIT-UH-IRTF Joint Campaign for NEO SpectralReconnaissance (PI R Binzel) were also used Taxonomicclassifications were obtained by fitting our spectra to the meanreflectance spectra of the Bus asteroid taxonomy (Bus amp Binzel2002) Small NEAs are the likely progenitors of meteorites animproved understanding of the abundance of meteorite parentbody types in the NEO population improves understanding of howthe two populations are related as well as the biases Earthsatmosphere imposes upon the meteorite collectionWe present classifications for these objects as well as results for thedebiased distribution of taxa(as a proxy for composition) as a function of object size andcompare to the observed fractions of ordinary chondritemeteorites and asteroids with d gt 1 km Amongst the smallestNEOs we find an unexpected distribution of taxonomic types thatdiffers from both large NEOs and meteoritesWe acknowledge funding support from NASA NEOO grant numberNNX14AN82G

1 2 22 1

1 2 22 1 3 2 2

4 5

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76

Author(s) Mary L Hinkle Nicholas Moskovitz DavidTrilling Richard P Binzel Cristina Thomas Eric Christensen Francesca DeMeo Michael J Person David Polishook MarkWillmanInstitution(s) 1 Catalina Sky Survey 2 Harvard-SmithsonianCenter for Astrophysics 3 Institute for Astronomy - U Hawaii 4Lowell Observatory 5 MIT 6 Northern Arizona University 7PSI 8 Weizmann Institute of Science

30105 ndash Constraining the shape distribution andbinary fractions of asteroids observed by NEOWISEKnowing the shape distribution of an asteroid population givesclues to its collisional and dynamical history Constraining lightcurve amplitudes (brightness variations) offers a first-orderapproximation to the shape distribution provided all asteroids inthe distribution were subject to the same observing biasesAsteroids observed by the NEOWISE space mission at roughly thesame heliocentric distances have essentially the same observingbiases and can therefore be inter-compared We used the archivalNEOWISE photometry of a statistically significant sample of JovianTrojans Hildas and Main belt asteroids to compare the amplitude(and by proxy shape) distributions of L4 vs L5 Trojans Trojans vsHildas of the same size range and several subpopulations of Mainbelt asteroidsFor asteroids with near-fluid rubble pile structures very large lightcurve amplitudes can only be explained by close or contact binarysystems offering the potential to catalog and characterize binarieswithin a population and gleaning more information on itsdynamical evolution Because the structure of most asteroids is notknown to a high confidence level objects with very high light curveamplitudes can only be considered candidate binaries In Sonnettet al (2015) we identified several binary candidates in the JovianTrojan and Hilda populations We have since been conducting afollow-up campaign to obtain densely sampled light curves of thebinary candidates to allow detailed shape and binary modelinghelping identify true binaries Here we present preliminary resultsfrom the follow-up campaign including rotation propertiesThis research was carried out at the Jet Propulsion Laboratory(JPL) California Institute of Technology (CalTech) under acontract with the National Aeronautics and Space Administration(NASA) and was supported by the NASA Postdoctoral Program atJPL We make use of data products from the Wide-field InfraredSurvey Explorer which is a joint project of the University ofCalifornia Los Angeles and JPLCalTech funded by NASA Thispublication also makes use of data products from NEOWISEwhich is a project of JPLCalTech funded by the Planetary ScienceDivision of NASA

Author(s) Sarah M Sonnett Amy Mainzer Tommy Grav Joseph Masiero James Bauer Pierre Vernazza Judit GyorgyeyRies Emily KramerInstitution(s) 1 Jet Propulsion Laboratory 2 LaboratoiredAstrophysique de Marseille 3 Planetary Science Institute 4University of Texas at Austin

30106 ndash Hilda Asteroid Compositions as anObservational Test of Giant Planet Migration ModelsMultiple lines of evidence indicate that planetary migration is a keypart of the evolution of planetary systems Planetary migrationmodels of the solar system suggest that the Jupiter Trojan andHilda stable resonances were repopulated during giant planetmigration We have completed a 4-year multi-epoch photomtericmulti-color survey of Hilda asteroids in order to determineindividual object composition The colors of ~500 Hildas are nowknown a factor of 3 increase in objects with determinedcompositions compared to the start of our observations We reportthe results of our survey in the context of the predictions fromcurrent dynamical migration models identify the modelinconsistent with the compositional results and address futureobservational data that is required in addition to Hilda asteroidcompositions to validate the Nice and Grand Tack modelsThis work supported by the University of MinnesotaUndergraduate Research Scholarship Program and NASAPlanetary Astronomy Grant NNX13AJ11G

Author(s) Erin L Ryan Charles E Woodward BenjaminSharkey Keith S NollInstitution(s) 1 Minnesota Institute for AstrophysicsUniversity of Minnesota 2 NASA GSFC 3 University ofMaryland

30107 ndash The Pan-STARRS search for Near EarthObjectsThe two Pan-STARRS telescopes located on Haleakala Hawaii are18-meter diameter telescopes equipped with 14 Gigapixel camerasthat deliver 7 square degree fields of view The first telescopePan-STARRS1 (PS1) has been conducting a survey for Near-EarthObjects The second telescope Pan-STARRS2 (PS2) is nearingcompletion The telescope was commissioned using an incompletefocal plane with only 18 good detectors (60 required) The camerais presently being upgraded and will be operated from October2015 with 60 detectors (some engineering grade) A final upgradeto the camera in early 2016 will make the telescope fullyoperationalThe two telescopes survey much of the sky accessible fromHaleakala multiple times each lunation The area surveyed rangesfrom +90 degrees in the north down to -475 degrees declination inthe south The ldquosweet spotsrdquo close to the Sun have been productivein discovery of large objectsThe PS1 survey is becoming more mature and productive havingdiscovered more than half of all NEOs in 2015 to date and morethan 60 of the larger NEOs and PHAs discovered in 2015 BothPS1 and PS2 deliver excellent astrometry and photometry PS1continues to discover a significant number of large (gt 1km) NEOsPS1 has become the leading discover of comets discovering morethan half of the new comets in both 2014 and 2015In good weather conditions the discovery rate of NEO candidatesby PS1 overwhelms the external NEO followup resourcesparticularly for fainter NEOs As a result we needed to repeat fieldsto recover NEO candidates As PS2 matures with a complete focalplane and when the G96 camera upgrade is complete thecombination of these three telescopes will facilitate a higher NEOdiscovery rate a better census of the NEOs in the sky and betterorbits for NEOs This will in turn lead to a better understanding ofthe size and orbit distribution of NEOs The Pan-STARRS NEOsurvey is also likely to discover asteroids suitable for the NASAasteroid retrieval missionSome early science highlights from the Pan-STARRS survey will bediscussed

Author(s) Richard J Wainscoat Kenneth Chambers EvaLilly Robert Weryk Serge Chastel Larry Denneau MarcoMicheliInstitution(s) 1 ESA NEO Coordination Centre 2 Univ ofHawaii

30108 ndash Olivine-rich asteroids in the main asteroidbeltOlivine-dominated asteroids classified as A-types withnear-infrared spectral measurements are largely thought to be themantle remnants of disrupted differentiated small bodies TheseA-type asteroids hold clues to asteroid differentiation and to thecollisional history of those differentiated bodies Preliminarystudies of the abundance and distribution of A-type asteroids wereperformed by Carvano et al (2010) and DeMeo amp Carry (20132014) using the Sloan Digital Sky Survey (SDSS) To confidentlyidentify these olivine-dominated A-type asteroids howevernear-infrared spectral measurements are needed to identify thedistinct broad and deep 1-micron olivine absorption feature Usingthe Sloan Digital Sky Survey Moving Object Catalog to select A-typeasteroid candidates we have performed a near-infrared spectralsurvey of over 70 asteroids with SpeX on the IRTF We present theabundance and distribution of A-type asteroids throughout themain asteroid belt and compare these results with similar surveysfor basalt-rich V-type asteroids (eg Moskovitz et al 2008) Thiswork is supported by NASA under grant number NNX12AL26Gissued through the Planetary Astronomy Program

6 46 5 7 1

2 5 83

1 1 31 1 2

4 1

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2 22 2 2 2

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77

Author(s) Francesca E DeMeo David Polishook BenoitCarry Nick Moskovitz Brian Burt Rick BinzelInstitution(s) 1 Lowell Observatory 2 Massachusetts Instituteof Technology 3 Nice Observatory

30109 ndash Revealing Secrets of Triple Asteroid Systemswith SPHEREA multiple-asteroid system provides otherwise unattainableinformation about the intrinsic properties of the system itself aswell as its formation and evolution Comparative spectroscopy andimaging of two large multiple main-belt asteroids (93) Minervaand (130) Elektra were performed using the newly commissionedSpectro-Polarimetric High-contrast Exoplanet Researchinstrument (SPHERE) on ESOs 82-m VLT A new moon (S2014(130) 1) of the known binary asteroid (130) Elektra wasdiscovered based on the SPHERE observations making (130)Elektra the sixth triple system detected in the asteroid belt We willpresent the component-resolved near infrared spectra from 09 to16 micron of the Minerva and the Elektra triple systems We willalso present the orbital solution and the dynamical simulations onthe two moons of (130) Elektra

Author(s) Bin Yang Zahed Wahhaj Laurene Beauvalet Franck Marchis Christophe Dumas Michaeumll MarssetInstitution(s) 1 Carl Sagan Center of the SETI Institute 2European Southern Observatory 3 Observatoacuterio Nacional Rio deJaneiro 4 TMT International Observatory

302 ndash Formation of Planets Satellites andSmall Bodies30201 ndash The collisional evolution of chondritic parentbodiesMost meteorites are fragments form recent collisions in theasteroid belt The collision speed between two objects of theasteroid belt is given by the eccentricity and inclination of theirrespective Keplerian orbits Typical values are on the order of a fewkm s In such a hyper-velocity collision the smaller collisionpartner (projectile) is destroyed whereas depending on the massratio of the colliding objects a crater on the larger body (target) isformed or the target is entirely destroyed too The present sizedistribution of the asteroid belt suggests that an asteroid with 100km radius is encountered ~10 times during the lifetime of theSolar System by objects larger than 10 cm in radius the formedcraters cover the surface of the asteroid about 100 timesWe will present a numerical study that simulates the statisticalbombardment on an asteroidal surface and tracks the resultingmorphological changes of the parent body due to the formation ofcraters the compaction of the material beneath the craters as wellas the formation of a regolith layer The crater ejecta from recentimpacts on a consolidated asteroid are then compared to the knownmeteorites particularly concerning the distribution of shock stagesComparing the compaction of ejected material from the simulatedcollisions that occurred during the last 20 Myrs which is the meancosmic ray exposure age of meteorites with shock stages ofmeteorites we find that meteorites most likely stem from smallerparent bodies that do not have a significant regolith layer Forlarger objects that inevitably accrete regolith layers a prediction ofthe thickness depending on the largest visible crater can be madeAdditionally we compare the crater distribution of an initially 100km (radius) large object with a shape model of asteroid (21)Lutetia assuming it to be initially formed spherical with a radiusthat is equal to its longest present ellipsoid length and find areasonable agreement Following our study predictions of theporosity of the surface and the interior of the asteroid as well as theshock stages of ejected material can be made

Author(s) Juumlrgen Blum Eike Beitz Mirta Gabriela ParisiInstitution(s) 1 Instituto Argentino de Radioastronomia 2 TUBraunschweig

30202D ndash Planetesimal Formation - Collisions ofDecimeter Ice and Dust

The early stages (from microm to mm) as well as the late stages (fromkm to planet size) of planet formation are quite well understoodThe intermediate stage of planetesimal formation is notunderstood in detail yet Several processes such as bouncing orradial drift can potentially stall growth beyond the millimeter orcentimeter size rangeThe collision dynamics of decimeter bodies are important inplanetesimal formation models They are interesting forcoagulation models as radial drift towards the central star becomessevere at sizes of decimeter to meter But they are also crucial forgravitational instability models because concentrationmechanisms are believed to be strongest for decimeter bodiesWe performed various collision experiments with decimeter as wellas centimeter bodies made up of both silicate dust and water iceWe investigated threshold conditions such as the threshold tofragmentation which are especially interesting for the coagulationmodelsThough mutual collisions might lead to bouncing or evenfragmentation already at velocities that are much lower thanrelative velocities expected in PPDs growth beyond decimeter sizesis still possible Decimeter bodies start to decouple from to thesurrounding gas which results in relative velocities to smallerbodies of several ms In such collisions of bodies of different sizesthe bigger body can gain mass This can be by direct mass transferfrom the smaller body Here the accretion efficiency is a crucialparameter Mass can also be transferred through gas-drivenre-accretion of fragments of the smaller body which are producedin the collision The velocity and size distribution of the ejectedfragments are significant for re-accretion

Author(s) Johannes Deckers Jens Teiser Gerhard WurmInstitution(s) 1 Universitaumlt Duisburg-Essen

30203 ndash Icy Collisions ndash Planet Building beyond thesnowlineCollisions of small icy and dust particles beyond the ldquosnow-linerdquo area key step in planet formation Whilst the physical forces thatunderpin the aggregation of the smallest grains (van der Waals)and the largest planetessimals (gravity) are well understood theprocesses involving mm ndash cm sized particles remain a mysteryIn a unique set of experiments we investigated low velocitycollisions of dust and icy particles in this size range undermicrogravity conditions ndash utilizing parabolic flight (eg Salter2009 Hill 2015 (a) amp (b)) Experiments were performed atcryogenic temperatures (below 140 K) for icy aggregates andambient as well as cryogenic temperatures (80 ndash 220 K) for dustaggregatesThe kinetic analysis of the observed collisions of different aggregatetypes in different shapes and sizes revealed astonishing results ndash asthe collisional properties of all investigated particles differ stronglyfrom the usual assumptions in models of planet formationHere we present a summary of the results on the collisions of icyparticles as well as first results on the collisions of dust aggregatesFocus will be on the coefficient of restitution which measures theloss of translational energy in bouncing collisions and is a keyparameter in models of planet formation

Author(s) Sabrina Gaertner Catherine Hill DanielHeisselmann Juergen Blum Helen FraserInstitution(s) 1 Technische Universitaet Braunschweig 2 TheOpen University

30204 ndash Forming the Terrestrial Planets from anAnnulusWe present results from the growth of planets directly fromplanetsimals initially constrained to a narrow annulus between07-10 AU The simulations examine the idea that the EarthMarsmass ratio can be explained when the planets form from atruncated disk with an outer edge at 10 AU Using the Lagrangiancode known as LIPAD we present results on the role offragmentation and the effects of interactions with the gas-disk onthe evolution of a large number of planetesimals as they grow toplanetsIn particular we report on simulations where initially the solids in

2 23 1 2 2

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-1

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78

the disk are planetesimals with the same initial radii (varied fromrun to run between 3 and 300 km) with and withoutfragmentation and with and without the effects of a gas-disk Thepresence of a gas disk strongly changes the outcomes of the firstfew million years of growth keeping accretion rates high throughlow relative velocity collisions Meanwhile fragmention processescan produce small particles that by way of dynamical friction canprovide some of the same dynamical affects as the gas-disk -though with the side effect of mass loss due to the grind of particlesto small sizes and subsequent drift out of the annulusIn sum the final planetary systems sometimes produceMars-analogs with appropriately small mass but due to dodiffusive spreading rather than violent scattering However theyrarely produce objects as massive as Earth and Venus do to thesame effect

Author(s) Harold F Levison Kevin WalshInstitution(s) 1 Southwest Research Inst

30205 ndash Planetsimals to Planets - RevisitingTerrestrial Planet FormationNearly all previous models of terrestrial planet formation focus oneither a short span of time or a narrow sliver of the disk tounderstand a specific mode of growth The final stages of growththe giant impact stage are typically picked up after the growth ofMoon- to Mars-sized embryos have grown and are spreadthroughout the diskHere by way of simulations starting with 30 km planetesimals thatspan the entire inner region of the Solar System from 07 to 30 auwe examine the growth throughout the entire disk We find thatthe growth is strongly inside-out with Mars-sized embryos formedinside of 1 au before any embryos are formed beyond 2 auFurthermore we test various effects owing to the existence ortimescale of dispersal of the gaseous solar nebula on the stages ofgrowth and timing of instabilities

Author(s) Kevin J Walsh Harold F LevisonInstitution(s) 1 Southwest Research Institute

30206 ndash Moon formation coupled with the protolulardiskIt is thought that the Moon accreted from the protolunar disk thatwas assembled after the last giant impact on Earth Due to its hightemperature the protolunar disk may act as a thermochemicalreactor in which the material is processed before beingincorporated into the Moon Outstanding issues likedevolatilisation and istotopic evolution are tied to the diskevolution however its lifetime dynamics and thermodynamics areunknown Here we numerically explore the long term viscousevolution of the protolunar disk using a one dimensional modelwhere the different phases (vapor and condensed) are verticallystratifiedOur major innovation is that we compute at the same time theproto-moon growth along with the disk evolution and calculate thethermodynamical equilibrium of the proto-lunar seed as it growsWe will discuss the long term dynamics thermodynamics coolingtimescale and possibility for volatile depletion We will show thatdue to different effective viscosities substantial fractionation ofvolatiles and refractory material is possibleFinally we will compare different scenarios of moon impacts(standard sub-earths fast spinning Earth) and their differentadvantages for explaining todayrsquos moon material content

Author(s) Sebastien Charnoz Lisa Bugnet Chloeacute MichautInstitution(s) 1 Universiteacute Paris Diderot

30207 ndash Lunar volatile depletion due to incompleteaccretion within an impact-generated diskThe Moon likely formed from a disk produced by a giant impactwith the Earth The Moon and the bulk silicate Earth (BSE) sharemany compositional similarities (eg Ringwood 1979 Dauphas etal 2014) However compared with the BSE the Moon is moredepleted in volatile elements including moderately volatile K andNa as well as more highly volatile elements eg Zn (eg OrsquoNeill

1991 Taylor amp Wieczorek 2014) The origin of this depletion ispoorly understood Prior results suggest escape (eg Paniello et al2012) but at least hydrodynamic escape appears minimal forexpected disk conditions (Nakajima amp Stevenson 2014)In the limit of no escape and a closed system a depletion couldinstead result if disk volatiles were preferentially accreted by theEarth rather than by the Moon Taylor et al (2006) advocated thatthe lunar depletion pattern is most consistent with incompletecondensation from an initially high temperature vapor with theaccretion of condensates by the Moon ldquocut-offrdquo at a temperatureallowing incorporation of a small component of alkalis (eg K andNa) but only a tiny fraction of more volatile elements (eg Zn)Neither the mechanism that would produce the cut-off nor whatthe relevant cut-off temperature would be in an oxygen-richprotolunar disk (eg Visscher amp Fegley 2013) were knownWe identify a mechanism wherein a depletion results because diskvolatiles are preferentially accreted by the Earth rather than by theMoon The Moon may acquire the final tens to 60 of its massfrom melt originating from the inner portions of the disk (Salmonamp Canup 2012) Initially the inner disk melt is hot andvolatile-poor but as the disk cools volatiles condense We combinedynamical thermal and chemical models to show that delivery ofinner disk material to the Moon effectively ends as gravitationalinteractions cause the Moonrsquos orbit to expand away from the diskwith this cut-off occurring prior to condensation of key depletedelements The portion of the Moon derived from the inner disk isthen volatile depleted even without escape This mechanism couldproduce part or all of the observed depletion pattern dependingprimarily on the degree of mixing within the Moon

Author(s) Robin M Canup Channon Visscher JulienSalmon Bruce FegleyInstitution(s) 1 Dordt College 2 Southwest Research Inst 3Washington University

30208 ndash Formation of Phobos and Deimos in anextended circum-Martian accretion diskRecent exploration of Phobos by Mars Express has renewed theinterest in the origin of the Martian moons which remains an openissue New studies have recently focused on accretion of debris in acircum-Martian disk Craddock (Icarus 2011) has proposed ascenario of formation of such a disk (about 10 to 10 the massof Mars) from a giant collision occurred early in Mars historyRosenblatt and Charnoz (Icarus 2012) have shown that moonletscan be formed with Phobos and Deimos masses in a compact diskclose to the planet Nevertheless the orbit of these moonletsrapidly recedes back to Mars and the moonlet system vanishes inmuch less than 1 GyCitron at al (Icarus 2015) have modeled the formation of a disk ofdebris resulting from a giant collision but with a larger mass (01 of Mars mass) than in Craddock (2011) They have shown thatmost of the disk mass is concentrated close to the planet but asmall part can extend beyond the synchronous limit (6 Mars radii)We study here the accretion of debris in an extended disk focusingin the edge of this disk where surface density of material is thelowest However we take into account the gravitational influenceof the more massive bodies formed in the denser part of the diskOur results highlight the driven mechanisms of accretion in acircum-Martian disk of debris

Author(s) Pascal Rosenblatt Seacutebastien Charnoz MarikoDunseath-Terao Kevin Dunseath Antony TrinhInstitution(s) 1 Laboratoire AIM Universiteacute Paris DiderotCEACNRS 2 Royal Observatory of Belgium 3 Universiteacute deRennes-I

30209 ndash Testing Migration of the Jupiter TrojanAsteroids in the LabTodayrsquos Jupiter Trojan asteroids may have orininated in the KuiperBelt (eg Morbidelli et al Nature 2005 Nesvorny et al ApJ 2013)and migrated to capture at their present locations If this is thecase it is expected that their surfaces will contain chemical traces ofthis history No distinct spectral bands have been conclusivelyidentified in the literature however visible and near-infrared

1 1

1 1

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79

spectra of Kuiper Belt Centaur and Trojan populations each showtwo sub-populations distinguished by their spectral slopes (Brownet al ApJL 2011 Emery et al AJ 2011) The slopes are all positive(or ldquoredrdquo) steepest in the Kuiper Belt and least steep in the Trojanpopulation Here we test the hypothesis that the asteroids formedspanning a stability line for a critical substance in this case we testsulfur as H S The hypothesis is that irradiating mixed icescontaining H S will result in a refractory residue of steeper slopethan the same composition without the H S We have simulatedthis history in the Minos chamber at the Icy Worlds SimulationLaboratory at NASArsquos Jet Propulsion Laboratory Ices that will bediscussed include a 3331 mixture of H S NH CH OH H Oand a 331 mixture of NH CH OH H O After deposition at 50K the ices were irradiated with a beam of 10 keV electrons to formthe refractory crust The ices were then warmed (while continuingirradiation) to 120 K and observed for several days Reflectancespectra were collected throughout the experiment in the visible andinfrared The spectral slope increased dramatically after irradiationof the mixture containing H S while the spectral slope for themixture without any sulfur changed very little This is consistentwith sulfur being the critical component determining which of thespectral populations an object belongs to in the present inventoryof outer solar system objects Quantitative analysis is underwayThis work has been supported by the Keck Institute for SpaceStudies (KISS) The research described here was carried out at theJet Propulsion Laboratory Caltech under a contract with theNational Aeronautics and Space Administration (NASA) and at theCaltech Division of Geological and Planetary Sciences

Author(s) Michael Poston Jordana Blacksberg MikeBrown Elizabeth Carey Robert Carlson Bethany Ehlmann John Eiler Kevin Hand Robert Hodyss Ahmed Mahjoub IanWongInstitution(s) 1 California Institute of Technology 2 JetPropulsion Laboratory

304 ndash Gerard P Kuiper Prize Chemistry ofPlanetary Atmospheres Insights andProspects Yuk Yung (Caltech)30401 ndash Chemistry of Planetary AtmospheresInsights and ProspectsUsing observations from the Mariners Pioneers VikingsVoyagers Pioneer Venus Galileo Venus Express CuriosityCassini New Horizons and numerous observatories both in orbitof Earth and on the ground I will give a survey of the majorchemical processes that control the composition of planetaryatmospheres For the first time since the beginning of the spaceage we understand the chemistry of planetary atmospheresranging from the primitive atmospheres of the giant planets to thehighly evolved atmospheres of terrestrial planets and small bodiesOur understanding can be distilled into three important ideas (1)The stability of planetary atmospheres against escape of theirconstituents to space (2) the role of equilibrium chemistry indetermining the partitioning of chemical species and (3) the role ofdisequilibrium chemistry which produces drastic departures fromequilibrium chemistry To these three ideas we must also add afourth the role of biochemistry at Earths surface which makes itsatmospheric chemistry unique in the cosmochemical environmentOnly in the Earths atmosphere do strong reducing and oxidizingspecies coexist to such a degree For example nitrogen species inthe Earths atmosphere span eight oxidation states from ammoniato nitric acid Much of the Earths atmospheric chemistry consistsof reactions initiated by the degradation of biologically producedmolecules Life uses solar energy to drive chemical reactions thatwould otherwise not occur it represents a kind of photochemistrythat is special to Earth at least within the Solar System It remainsto be seen how many worlds like Earth there are beyond the SolarSystem especially as we are now exploring the exoplanets usingKepler TESS HST Spitzer soon to be launched missions such asJWST and WFIRST and ground-based telescopes Theatmospheres of the Solar System provide a benchmark for studyingexoplanets which in turn serve to test and extend our current

understanding of planetary atmospheres Ultimately we may beable to answer these profound questions Are we alone in theuniverse What makes a planet habitable How does life originateAnd what is the destiny for life on our own planet

Author(s) Yuk YungInstitution(s) 1 Caltech

305 ndash MAVEN Mission to Mars Results onUpper Atmosphere Ionosphere Solar-WindInteractions and Escape to Space BruceJakosky (University of Colorado)30501 ndash MAVEN Mission to Mars Results on UpperAtmosphere Ionosphere Solar-Wind Interactionsand Escape to SpaceThe Mars Atmosphere and Volatile Evolution (MAVEN) spacecrafthas been orbiting Mars since 21 September 2014 and collecting datain science mode since 16 November 2014 The science objectives ofthe MAVEN mission are to characterize the upper atmosphere andionospheric structure and composition the interactions of the sunand the solar wind with the planet and the processes driving loss ofgas from the atmosphere to space Our goal is to understand thechain of processes leading to escape today learn how to extrapolateback in time and determine the integrated loss of atmosphere overMartian history Measurements are being collected from all of thescience instruments in our normal mapping orbit and throughmultiple ldquodeep diprdquo campaigns Results are providing a first-timecomprehensive look at the upper-atmospheric system surroundingMars and are elucidating the key processes and history of theatmosphere Results will be integrated into a coherent view of theprocesses controlling the upper-atmosphere system and the escapeto space

Author(s) Bruce M JakoskyInstitution(s) 1 Univ of Colorado

306 ndash New Views on Inner Solar Systemsand Extreme Planets Rebekah Dawson(University of California Berkeley)30601 ndash New Views on Inner Solar Systems andExtreme PlanetsAn abundance of exoplanets have been discovered with orbitalperiods shorter than Mercuryrsquos including thousands of planets andplanet candidates found by the Kepler Mission and over a hundredby radial velocity surveys The abundance and properties of theseshort-period planets have inspired new views on planet formationand evolution in the inner regions of solar systems I will reviewresults that have caused major shifts or debates in theories ofplanet formation including where and when planets (and theirbuilding blocks) form I will highlight problems that constraintsfrom the large observed population of exoplanets are particularlywell-suited to address despite our limited knowledge of mostindividual exoplanets I will also argue for the power of the mostextreme exoplanets to serve as exceptions that prove the rulerdquo fortheories of how planets form and evolve Ongoing statistical andtheoretical studies as well as complementary exoplanetobservations from upcoming missions will help addressoutstanding questions in planet formation

Author(s) Rebekah Ilene DawsonInstitution(s) 1 University of California Berkeley

307 ndash Asteroid Spin States30701 ndash A path to asteroid bulk densitiesSimultaneous size and shape optimization fromoptical lightcurves and Keck disk-resolved data

22

2

2 3 3 23 3 2

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A reliable bulk density of an asteroid can be determined from theknowledge of its volume and mass This quantity provides hints onthe internal structure of asteroids and their origin We computevolume of several asteroids by scaling sizes of their 3D shapemodels to fit the disk-resolved images which are available in theKeck Observatory Archive (KOA) and the Virtual ObservatoryBinary Asteroids Database (VOBAD) The size of an asteroid isoptimized together with its shape by the All-Data AsteroidModelling inversion algorithm (ADAM Viikinkoski et al 2015AampA 576 A8) while the spin state of the original convex shapemodel from the DAMIT database is only used as an initial guess forthe modeling Updated sets of optical lightcurves are usuallyemployed Thereafter we combine obtained volume with massestimates available in the literature and derive bulk densities fortens of asteroids with a typical accuracy of 20-50On top of that we also provide a list of asteroids for which (i) thereare already mass estimates with reported uncertainties better than20 or their masses will be most likely determined in the futurefrom Gaia astrometric observations and (ii) their 3D shape modelsare currently unknown Additional optical lightcurves are necessaryin order to determine convex shape models of these asteroids Ourweb page (httpsasteroid-obsocaeufoswikibinviewMainPhotometry) contains additional information about thisobservation campaign

Author(s) Josef Hanus Matti Viikinkoski Franck Marchis Josef DurechInstitution(s) 1 Astronomical Institute Faculty of Mathematicsand Physics Charles University in Prague V Holesovickach 218000 Prague Czech Republic 2 Department of MathematicsTampere University of Technology PO Box 553 33101 TampereFinland 3 Laboratoire Lagrange UMR7293 Universite de la CotedAzur CNRS Observatoire de la Cote dAzur Blvd delObservatoire CS 34229 06304 Nice cedex 4 France 4 SETIInstitute Mountain View Mountain View CA United States

30702 ndash A Review of Asteroid Rotation Statistics withand without the Results from Wide-field SurveysSeveral recent wide-field surveys eg Waszczak et al (2015) andChang et al (2015) have added more than 10000 asteroid rotationrates to the asteroid lightcurve database (LCDB) Warner et al(2009) In previous works Harris et al (2012) Warner et al(2011) we explored the possible effects on asteroid rotationalstatistics with the large infusion of results from such surveysespecially if using ldquosparserdquo data sets eg those with fewer than 60data points from a short span of 2-4 nightsNow that such data sets exist we examine asteroid rotationstatistics with and without the results from the surveys looking attwo specific points 1) the possible biases introduced when usingsurvey data and 2) assuming that the stated results are statisticallyuseful what the larger data set now tells us about asteroid rotationratesFor point 1 there appears to be the expected substantial biasesagainst low amplitude and very short or long period lightcurveswith the period problems stemming from the observing cadenceand limited number of observations Furthermore the two latestsurveys found periods for only about 20 of all observed objectsmeaning that only the ldquoeasierrdquo results were found While the twosurveys tended to go deeper and therefore work smaller objectsthat raises yet another bias success in finding a period depends onbrightness As a result we would urge caution when interpretingspin properties versus sizeFor point 2 we first note that the vast majority of objectsobserved by the two surveys were in the broad regions of the inneror outer main-belt Significantly less than 10 NEAs were observedFor this reason it makes it difficult to compare the effects of YORPas seen by rotation rate distribution on small asteroids at differentdistances When considering main-belt objects with 10 lt D lt 40km the difference between plots with and without survey datashow essentially the same Mawellian-like distribution

Author(s) Brian D Warner Alan W Harris Robert DStephensInstitution(s) 1 Center for Solar System Studies - Palmer DivideStation 2 Center for Solar System Studies - Trojan Station 3MoreData

30703 ndash Rotational Properties of Jupiter Trojan 1173AnchisesAnchises (1173) is a large Trojan asteroid librating about JupiterrsquosL5 Lagrange point Here we examine its rotational and lightcurveproperties by way of data collected over a 35 year observingcampaign The length of the campaign means that data weregathered for more than a quarter of Anchises full orbital revolutionwhich allows for accurate determinations of pole orientation andbulk shape properties for the asteroid that can then be compared toresults of previous work (ie French 1987 Horner et al 2012) Inaddition to light curves photometric data taken during thiscampaign could potentially detect color differences betweenhemispheres as the viewing geometry changes over timeUnderstanding these details about a prominent member of theJupiter Trojans may help us better understand the history of thisfascinating and important group of asteroids

Author(s) Joseph Chatelain Todd Henry Linda French David TrillingInstitution(s) 1 Georgia State University 2 Illinois WesleyanUniversity 3 Northern Arizona University 4 RECONS Institute

30704 ndash Improved Algorithms for Radar-BasedReconstruction of Asteroid Spin States and ShapesEarth-based radar is a powerful tool for gathering informationabout bodies in the Solar System Radar observations candramatically improve the determination of the physical propertiesand orbital elements of small bodies (such as asteroids andcomets) An important development in the past two decades hasbeen the formulation and implementation of algorithms forasteroid shape reconstruction based on radar dataBecause of the nature of radar data recovery of the spin statedepends on knowledge of the shape and vice versa Even withperfect spin state information certain peculiarities of radar images(such as the two-to-one or several-to-one mapping betweensurface elements on the object and pixels within the radar image)make recovery of the physical shape challenging This is acomputationally intensive problem potentially involving hundredsto thousands of free parameters and millions of data pointsThe method by which radar-based shape and spin state modellingis currently accomplished a Sequential Parameter Fit (SPF) isrelatively slow and incapable of determining the spin state of anasteroid from radar images without substantial user interventionWe implemented a global-parameter optimizer and Square RootInformation Filter (SRIF) into the asteroid-modelling softwareshape This optimizer can find shapes more quickly than thecurrent method and can determine the asteroidrsquos spin stateWe ran our new algorithm along with the existing SPF throughseveral tests composed of both real and simulated data Thesimulated data were composed of noisy images of procedurallygenerated shapes as well as noisy images of existing shape modelsThe real data included recent observations of both 2000 ET70 and1566 IcarusThese tests indicate that SRIF is faster and more accurate thanSPF In addition SRIF can autonomously determine the spin stateof an asteroid from a variety of starting conditions a considerableadvance over the existing algorithm We will present the results ofthese comparisons along with several visualizations of the shapeand spin state fitting process

Author(s) Adam Greenberg Jean-Luc MargotInstitution(s) 1 University of California Los Angeles

30705 ndash Rotation Frequencies of Small Jovian TrojanAsteroids An Excess of Slow RotatorsSeveral lines of evidence support a common origin for and possiblehereditary link between cometary nuclei and jovian Trojanasteroids Due to their distance and low albedos few comet-sized

3 2 41

1 32

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81

Trojans have been studied We discuss the rotation properties ofJovian Trojan asteroids less than 30 km in diameterApproximately half the 131 objects discussed here were studiedusing densely sampled lightcurves (French et al 2015a b)Stephens et al 2015) and the other half were sparse lightcurvesobtained by the Palomar Transient Factory (PTF Waszcazk et al2015)A significant fraction (~40) of the objects in the ground-basedsample rotate slowly (P gt 24h) with measured periods as long as375 h (Warner and Stephens 2011) The PTF data show a similarexcess of slow rotators Only 5 objects in the combined data sethave rotation periods of less than six hours Three of these fastrotators were contained in the data set of French et al these threehad a geometric mean rotation period of 529 hours A prolatespheroid held together by gravity rotating with this period wouldhave a critical density of 043 gmcm a density similar to that ofcomets (Lamy et al 2004)Harris et al (2012) and Warner et al (2011) have explored thepossible effects on asteroid rotational statistics with the resultsfrom wide-field surveys We will examine Trojan rotation statisticswith and without the results from the PTF

Author(s) Linda M French Robert D Stephens David JJames Daniel Coley Kyle ConnourInstitution(s) 1 Center for Solar System Studies 2 Cerro TololoInteramerican Observatory 3 Illinois Wesleyan Univ

30706 ndash Internal turmoil of small primitive bodiesrock-water-organic processing as context for Bennuand JUThe OSIRIX-REx (NASA 101955 Bennu) and Hayabusa 2 (JAXA1999 JU3) missions are set to explore small porous and primitiveasteroids (C and B type) Such bodies should contain organiccompounds and hydrated minerals Thus it is of great interest todecipher the internal structure and composition how it evolvedand how representative is the surface of the bulk interior For thiswe need to understand the physical conditions which drive thechemical evolution of water and organic-rich material through aporous medium as even main-belt asteroids of various sizes couldhave incorporated water ice upon formation Indeed the meteoriticrecord reveals such evidence in the form of hydrated mineralsmostly in the CI CM and CR carbonaceous chondrites which alsoindicate that more complex physical-chemical interactions undervarious conditions must have happened early on and set thecompositions and lithologies we observe today The precursorbodies may have also undergone early evolution and internalprocessing of mineral and organic reservoirs If conditions are metand sustained exothermic reactions (eg serpentinization andFischer-Tropsch) can contribute greatly to the overall heatingbalance and compositional variationOur thermal evolution code can deal with mixtures of water silicateminerals and organic compounds with relevant transitions andinteractions as a function of the thermodynamic variables We willutilize the robustness of the code to examine different origin andearly evolution scenarios such as parent-body evolution increasedcollision input early on orbital evolution at furthercloserperihelia varied initial composition and buried reservoirs ofvolatile compounds We will further examine the boundaryconditions in surface and near-surface layers by calculating heattransfer effects in granular material including conductionradiation and advection between particles and pores The granularmaterial can further react to vapor flows and small impactseffectively changing the diffusivity and conductivity of surfacelayersWe will present preliminary integrative models for internalevolution from formation to current state as a reactive rock-water-organic porous system

Author(s) Gal SaridInstitution(s) 1 Florida Space Institute U of Central Florida

30707 ndash Preliminary Light Curve Results of NEOsfrom the Characterization and Astrometric Follow-UpProgram at Adler Planetarium

We are nearing the halfway mark of a two-year program fornear-Earth object (NEO) astrometric follow-up andcharacterization utilizing 500 hours of observing time per year withthe Astrophysical Research Consortium (ARC) 35-meter telescopeat Apache Point Observatory (APO) Our observing is divided intotwo-hour blocks approximately every other night for astrometry(see poster by K A Nault et al) and several half-nights per monthfor spectroscopy (see poster by M Hammergren et al) and lightcurve studiesWe present preliminary results from variable photometryobservations as part of the characterization portion of the AdlerPlanetariumrsquos NEO program The frequent scheduling of half-nightobserving time allows us to capture data for small NEOs near thetime when they are closest to Earth before their apparentmagnitudes rapidly diminish beyond the range of detectability Wesearched for variability in newly discovered NEOs that had closeapproaches to Earth near the time of observation These include2014 RQ17 2014 SB145 2014 SF304 2014 WO4 2014 WY119 and2015 BC In addition we observed 2340 Hathor and 2007 EC whenthey each made a close approach to Earth to compare with lightcurves and magnitude variation constraints from previousapparitions We will construct light curves for all of the objectslisted above and determine rotational periods for those withsufficient temporal coverageThe targets were selected from candidates in the JPL NEO EarthClose Approaches table Arecibo planetary radar targets and theGoldstone asteroid radar schedule Due to the sensitivity of AGILEwe restricted our targets to those with apparent magnitudes in Vless than 19 magnitudesObservations were made using the frame transfer CCD cameraAGILE on the ARC 35-meter telescope AGILE has a field-of-viewof 22x22 and a plate scale of 0258rdquopixel with 2x2 binningThis work is based on observations obtained with the Apache PointObservatory 35-meter telescope which is owned and operated bythe Astrophysical Research Consortium We gratefullyacknowledge support from NASA NEOO award NNX14AL17G andthank the University of Chicago Department of Astronomy andAstrophysics for observing time in 2014

Author(s) Melissa J Brucker Kristie A Nault MarkHammergren Jennifer Sieben Geza Gyuk Michael RSolontoiInstitution(s) 1 Adler Planetarium 2 Illinois WesleyanUniversity 3 Lynchburg College

30708 ndash Spin-Spin Coupling in Asteroidal BinariesGravitationally bound binaries constitute a substantial fraction ofthe small body population of the solar system and characterizationof their rotational states is instrumental to understanding theirformation and dynamical evolution Unlike planets numeroussmall bodies can maintain a perpetual aspheroidal shape givingrise to a richer array of non-trivial gravitational dynamics In thiswork we explore the rotational evolution of triaxial satellites thatorbit permanently deformed central objects with specific emphasison quadrupole-quadrupole interactions Our analysis shows that inaddition to conventional spin-orbit resonances both prograde andretrograde spin-spin resonances naturally arise for closely orbitinghighly deformed bodies Application of our results to theillustrative examples of (87) Sylvia and (216) Kleopatra multi-asteroid systems implies capture probabilities slightly below ~10for leading-order spin-spin resonances Cumulatively our resultssuggest that spin-spin coupling may be consequential for highlyelongated tightly orbiting binary objects

Author(s) Konstantin Batygin Alessandro MorbidelliInstitution(s) 1 California Institute of Technology 2Observatoire de la Cocircte dAzur

30709 ndash Surprise The oft-ignored Moon mightactually be important for changing the spins ofasteroids during Earth flybysAnalysis near-Earth asteroid archival data has revealed thatasteroids with Earth MOIDs (minimum orbit intersection distancea proxy for flyby distance) smaller than 10-15 lunar distances have

3

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a systematically larger dispersion in spin rate than more distantflybys (Siu et al 2015 DPS) While tidal torques during closeencounters are expected to alter the spin states of asteroids (egScheeres et al 2000 Icarus) there is no intrinsic reason to expectthe observed sharp transition in spin rate distribution at 10-15lunar distances as tidal forces drop off smoothly with distanceWhile the Moon itself is too diminutive to directly alter thespin-states of asteroids we show that its presence is enough tosignificantly affect asteroid encounter trajectories Asteroidsentering the Earth-Moon system are subject to three-bodydynamics (due to the combined gravitational effects of the Earthand Moon) Depending on the flyby geometry the Moon can act asa temporary sink for the asteroids geocentric orbital energy Thisallows some fraction of asteroids to have closer approaches withthe Earth than expected when considering the Earth-Moonbarycenter alone In rare cases (~01) this process enables thecapture of temporary moons around the Earth (Granvik et al 2012Icarus) Asteroids that undergo these enhanced flybys can haveboth closer-than-expected encounter distances (resulting in moresignificant tidal perturbations) and repeated encounters with theEarth and Moon before leaving the system (resulting in theaccumulation of multiple tidal interactions) By numerically solvingthe circular restricted three-body problem we show that thisprocess naturally produces a sharp transition in the asteroidpopulation asteroids with MOIDs less than 15 lunar distances canundergo these enhanced close approaches possibly explaining thesharp transition in the dispersion of asteroid spin rates at thisdistance Future work will investigate the efficiency of this processand the relationship between the physical response of the asteroidto tidal perturbations and the statistical distribution of asteroid spinrates

Author(s) James Tuttle Keane Hosea C Siu Nicholas AMoskovitz Richard P BinzelInstitution(s) 1 Lowell Observatory 2 Massachusetts Instituteof Technology 3 University of Arizona

30710 ndash Distributions of spin axes and shapes ofasteroidsWe developed a new simplified model for the determination ofshapes and spin states of asteroids to fully exploit photometric datasparse in time (few measurements per night) which are producedby all-sky surveys and were re-calibrated into the Lowellphotometric database by Bowell et al (2014) We model asteroidsas geometrically scattering triaxial ellipsoids The model comparesobserved values of mean brightness and the dispersion ofbrightness with computed values obtained from the parameters ofthe model ndash ecliptical longitude λ and latitude β of the pole and theratio ab of axes of the ellipsoid These parameters are optimized toget the best agreement with the observation We revealed that thedistribution of λ for the main-belt asteroids is anisotropic (inagreement with findings of Bowell et al (2014)) and dependent onthe inclination of orbit (for sin i lt 004 there is an excess of λ ~ 70deg+- 180deg) We are looking for a physical or observationalmechanism that would explain this distribution From the analysisof the distribution of ab we found that larger asteroids (D gt 25km) are more often spherical (ab ~ 1) than the smaller

Author(s) Helena Cibulkova Josef Durech MikkoKaasalainen Edward Bowell Dagmara OszkiewiczInstitution(s) 1 Astronomical Institute of the CharlesUniversity 2 Astronomical Observatory Institute A MickiewiczUniversity 3 Department of Mathematics Tampere University ofTechnology 4 Lowell Observatory

30711 ndash Looking for Kilometer-Sized Super-Fast-Rotators Using PTFWe have carried out three 6-field (~40 square deg each) asteroidrotation surveys using PTF with 10 min cadence to searh forkilometer-sized super-fast rotators (SRF) in 2014 Nov 2015 Janand 2015 Feb From these surveys we found several SFRcandidates showing reasonable folded lightcurves With thesecandidates we estimate that the population of SFR is ~01 ofrubble-pile asteroid

Author(s) Chan-Kao Chang Hsing-Wen Lin Wing-HuenIpInstitution(s) 1 Institute of Astronomy National CentralUniversity Taiwan

30712 ndash Nutation damping in viscoelastic tumblingrotatorsPresently 138 asteroids show signs of being in non-principal spinstates (Warner et al 2009 updated September 2015) Such spin isoften called `tumble or `wobble The instantaneous rotation axisof a wobbling body performs nutation about the direction of the(conserved) angular-momentum vector Incited by collisions andYORP wobble is mitigated by internal dissipation due to thenutation-caused alternating stresses inside the asteroidThe knowledge of the timescale related to the damping of thenutation angle is complementary to the knowledge of thetimescales associated with collisions and YORP Previousevaluations of the nutation relaxation rate were based on aninherently inconsistent approach that may be called Q-modelFirst the elastic energy in a periodically deforming rotator wascalculated in assumption of the deformation being elasticTherefrom the energy dissipation rate was determined byintroducing an ad hoc quality factor Q This ignored the fact thatfriction (and the ensuing existence of Q) is due to deviation fromelasticityWe use the viscoelastic Maxwell model which naturally impliesdissipation (as any other viscoelastic model would) In thisapproach we compute the power and damping time for an oblateellipsoid and a prism Now the viscosity assumes the role of theproduct μQ in the empirical Q-model with μ being the rigidityContrarily to the Q-model our model naturally gives a nulldissipation for a shape tending to a sphere We also explore whenthe constant part of the stress can be ignored in the derivation ofthe damping time The neglect of prestressing turns out to belegitimate for the mean viscosity exceeding a certain thresholdvalue

Author(s) Julien Frouard Michael EfroimskyInstitution(s) 1 US Naval Observatory

30713 ndash Photometric Follow-up of Asteroid 4660Nereus and Reanalysis of its YORP EffectWe carried out new photometric observations of small near-Earthasteroid 4660 Nereus in 2013 and reanalyzed the secular change inthe asteroid rotation period due to the YORP effect The shape andpole orientation of Nereus have been derived from the radarobservations which predicts that a detectable change could occurin a few years (Brozovic et al 2009) Since the YORP-inducedlinear change of rotation period leads to a phase lag that isquadratic in time we examined it by comparing 22 lightcurvesobserved in 1997-2013 with the modeled ones The new dataset oflightcurves enabled us to further constrain the solutions of theasteroid rotational state and we found that it would be difficult toreproduce the observed lightcruves with a constant-period model

Author(s) Kohei Kitazato Shinsuke Abe MasateruIshiguro Yukihiro Ishibashi Yuhei Takagi Masanao AbeInstitution(s) 1 Japan Aerospace Exploration Agency 2 NihonUniversity 3 Seoul National University 4 University of Aizu 5University of Hyogo

308 ndash Asteroid Observational Surveys30801 ndash The Near-Earth Object Camera ANext-Generation Minor Planet SurveyThe Near-Earth Object Camera (NEOCam) is a next-generationasteroid and comet survey designed to discover characterize andtrack large numbers of minor planets using a 50 cm infraredtelescope located at the Sun-Earth L1 Lagrange point Proposed toNASAs Discovery program NEOCam is designed to carry out acomprehensive inventory of the small bodies in the inner regionsof our solar system It address three themes 1) quantify thepotential hazard that near-Earth objects may pose to Earth 2)

3 21 2

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1 11

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83

study the origins and evolution of our solar system as revealed byits small body populations and 3) identify the best destinations forfuture robotic and human exploration With a dual channelinfrared imager that observes at 4-5 and 6-10 micron bandssimultaneously through the use of a beamsplitter NEOCamenables measurements of asteroid diameters and thermal inertiaNEOCam complements existing and planned visible light surveysin terms of orbital element phase space and wavelengths sincealbedos can be determined for objects with both visible andinfrared flux measurements NEOCam was awarded technologydevelopment funding in 2011 to mature the necessary megapixelinfrared detectors

Author(s) Amy K Mainzer Edward L Wright JamesBauer Tommy Grav Roc M Cutri Joseph Masiero Carolyn RNugentInstitution(s) 1 IPACCaltech 2 JPL 3 PSI 4 UCLA

30802 ndash Asteroid Detection Results Using the SpaceSurveillance TelescopeFrom 1998-2013 MIT Lincoln Laboratory operated a highlysuccessful near-Earth asteroid search program using two 1-moptical telescopes located at the MIT Lincoln LaboratoryExperimental Test Site (ETS) in Socorro NM In 2014 the LincolnNear-Earth Asteroid Research (LINEAR) program successfullytransitioned operations from the two 1-m telescopes to the 35-mSpace Surveillance Telescope (SST) located at Atom Site on WhiteSands Missile Range NM This paper provides a summary offirst-year performance and results for the LINEAR program withSST and provides an update on recent improvements to themoving-object pipeline architecture that increase utility of SST datafor NEO discovery and improve sensitivity to fast-moving objectsRuprecht et al (2014) made predictions for SST NEO searchproductivity as a function of population model This paper assessesthe NEO search performance of SST in the first 15 years ofoperation and compares results to model predictionsThis work is sponsored by the Defense Advanced Research ProjectsAgency and the National Aeronautics and Space Administrationunder Air Force Contract FA8721-05-C-0002 The viewsopinions andor findings contained in this articlepresentation arethose of the authors presenters and should not be interpreted asrepresenting the official views or policies of the Department ofDefense or the US Government Distribution Statement AApproved for public release distribution unlimited

Author(s) Jessica D Ruprecht Gregory Ushomirsky Deborah F Woods Herbert E M Viggh Jacob Varey Mark ECornell Grant StokesInstitution(s) 1 MIT Lincoln Laboratory 2 MITLL ETS FieldSite

30803 ndash Absolute magnitudes and slope parametersfor 250000 asteroids observed by Pan-STARRS1Absolute magnitude (H) of an asteroid is used for thedetermination of its diameter and apparent brightness Theobserved brightness changes as a function of asteroids geometrywith respect to the Sun and Earth and surface properties of theasteroid which is described by a phase function depending on theslope parameter (G) H and G parameters are derived from mostlyoptical observations of asteroids Nowadays databases of asteroidobservations contain millions of entries coming from multipletelescopic surveys employing different photometric calibrationsand standards They usually lack information on photometricerrors and photometric precision is truncated above thephotometric accuracy of current major surveys We derived H andG of almost 250000 asteroids observed by a single survey ndashPan-STARRS1 - during its first 15 months of operation 1250000detections in our sample were filtered by morphological parametersand photometric quality and achieved photometric errors less than004 mag Our method was based on Monte Carlo technique and asparse Bayesian marginalization over taxonomic classification lightcurve amplitude and period and both Bowells (1989) andMuinonens (2010) phase functions Resulting H and G valueswere derived with statistical and systematic uncertainties and

errors The method was tested by comparison with accurate resultsfor about 500 asteroids provided by Pravec et al (2012) and resultsagree with Oszkiewicz et al (2012) work Our results confirm thatthe bias discovered by Juric et al (2002) and confirmed by Parkeret al (2008) and Pravec et al (2012) is still present in Minor PlanetCenter photometry The trend of G depending on semi-major axiswas confirmed as well Derived table of H and G and other relevantparameters is publicly available at httpwwwifahawaiieduNEO This work was supported by NASA grant NoNNX12AR65G

Author(s) Peter Veres Robert Jedicke Alan Fitzsimmons Larry Denneau Mikael Granvik Bryce Bolin Serge Chastel Richard WainscoatInstitution(s) 1 Institute for Astronomy University of Hawaii2 Jet Propulsion Laboratory California Institute of Technology 3Queenrsquos University 4 University of Helsinki 5 UNS-CNRS-Observatoire de la Cote dlsquoAzur

30804 ndash Dormant Comets in the Near-Earth AsteroidPopulationThe population of near-Earth objects comprises active comets andasteroids covering a wide range of dynamical parameters andphysical properties Dormant (or extinct) comets masquerading asasteroids have long been suspected of supplementing thenear-Earth asteroid (NEA) population We present a search forasteroidal objects of cometary origin based on dynamical andphysical considerations Our study is based on albedos derivedwithin the ExploreNEOs program and is extended by adding datafrom NEOWISE and the Akari asteroid catalog We use a statisticalapproach to identify asteroids on orbits that resemble those ofshort-period near-Earth comets using the Tisserand parameterwith respect to Jupiter the aphelion distance and the minimumorbital intersection distance with respect to Jupiter We identify atotal of 23 near-Earth asteroids from our sample that are likely tobe dormant short-period near-Earth comets and based on ade-biasing procedure applied to the cryogenic NEOWISE surveyestimate both magnitude-limited and size-limited fractions of theNEA population that are dormant short-period comets We findthat 03-33 of the NEA population with H lt= 21 and 9(+2-5)of the population with diameters d gt= 1 km are dormant short-period near-Earth comets We also present an observation programthat utilizes the 18m Vatican Advanced Technology Telescope(VATT) on Mt Graham AZ to identify dormant comet candidatesand search for activity in these objects Our targets are NEAs oncomet-like orbits based on the dynamical criteria derived in theabove study that are accessible with the VATT (V lt= 22) Weidentify dormant comets based on their optical spectral sloperepresented by V-R color measurements as albedo measurementsfor most of these objects are not available For each target wemeasure and monitor its V magnitude in order to reveal activityoutbreaks We also search for extended emission around ourtargets using deep imaging and a point-spread-function subtractiontechnique that allows us to obtain an upper limit on the dustproduction rate in each target We present preliminary results fromthis program This work is supported in part by funding from theSpitzer Science Center

Author(s) Michael Mommert Alan W Harris MichaelMueller Joseph L Hora David E Trilling Matthew Knight William F Bottke Cristina Thomas Marco Delbo Josh PEmery Giovanni Fazio Howard A SmithInstitution(s) 1 Deutsches Zentrum fuer Luft- und Raumfahrt2 Harvard-Smithsonian CfA 3 Lowell Observatory 4 NorthernArizona University 5 Observatoire de la Cote dAzur 6 PSI 7SRON 8 SWRI 9 University of Tennessee

30805 ndash The Asteroid 2015 KA122The Asteroid ldquo2015 KA122rdquo was discovered on May 252015 by theCatalina Sky Survey This object is not well known Its absolutemagnitude of 232 indicates a diameter of about 70 meters Theasteroid was at aproximately 33 lunar distances from the Earth onJune 62015 It has an orbital period of 211 years From ourObservatory located in Pasto-Colombia we captured several

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84

pictures videos and astrometry data during three days Our datawas published by the Minor Planet Center (MPC) and also appearsat the web page of NEODyS Our observatoryrsquos code at the MPC isldquoH78rdquo Pictures of the asteroid were captured with the followingequipment 14rdquo LX200 GPS MEADE (f10 Schmidt-CassegrainTelescope) and STL-1001 SBIG camera Astrometry was carriedout and we calculated the orbital elements We obtained thefollowing orbital parameters eccentricity = 04089630 +-000189 semi-major axis = 164254884 +- 000505 AU orbitalinclination = 1268490 +- 0039 deg longitude of the ascendingnode = 7314715 +- 00013 deg argument of perihelion =21482393 +- 0007 deg orbital period = 211 years (76890 days)mean motion = 046819485 +- 000216 degd perihelion distance= 097080706 +- 0000119 AU aphelion distance = 231429061+- 00103 AU The parameters were calculated based on 81observations (2015 June 3-5) with mean residual = 0343arcseconds Our videos appear in the following linkshttpspaceweathergallerycomindiv_uploadphpupload_id=113197httpspaceweathergallerycomindiv_uploadphpupload_id=113238ampPHPSESSID=f2lkigjogsfgcmi1rscc9jil36httpspaceweathergallerycomindiv_uploadphpupload_id=113257

Author(s) Alberto Quijano Vodniza Mario Rojas PereiraInstitution(s) 1 University of Narino Observatory

30806 ndash Target-of-Opportunity Characterization of100-Meter Class Near-Earth AsteroidsIt is generally believed that minor planet rotation periods smallerthan ~2 hours are indicative of non-negligible tensile strength forthese objects [1] This would put limits on the degree of fracture oreven suggest a monolithic structure for fast rotating asteroidsCombining rotations rates with spectral information for 100-meterclass Near-Earth asteroids (NEAs) can provide an even betterunderstanding of the physical properties and collisional history ofthe smaller members of the asteroid population which are alsothose that will impact the Earth with the most frequencyRobust characterization of 100-meter class asteroids is usuallylimited to when these objects make close approaches to the EarthThe observing window for such studies is usually weeks days orfor the smallest members of this population just a single day ortwo bracketing their closest approach to Earth For many the onlyoptimal occasions for investigation for the foreseeable future occurimmediately after discovery Therefore these are truly targets-of-opportunityAs part of an effort to obtain astrometric data on newly discoverednear-Earth asteroids using the Magdalena Ridge Observatoryrsquos(MRO) 24-meter telescope a program has been implemented toobtain rotation rate and spectral information on 100-meter classand smaller NEAs [2] Prioritized are recently discovered objectsthat have limited observing prospects Results thus far have shownthat although slow rotators do exists in this size regime about 70of our targets with absolute magnitude Hgt22 have rotation periodsless than 2 hours In addition approximately 20 of our targetshave indicated tumbling behavior with primary periods rangingfrom hours to minutes Therefore any origin model must beconsistent with the observed rotation rate distribution allow forthe existence of a significant fraction of tumblers and be consistentwith the evolving spectral class distribution For this effort wequantify the observing window that exists for various objects in thissize regime using the MRO 24-meter telescope We then present asample of recent lightcurve and spectral results from this program[1] Pravec et al Asteroids III 2002[2] Ryan and Ryan DPS 2014

Author(s) William Ryan Eileen V RyanInstitution(s) 1 NM TechMRO

30807 ndash Radar Observations of Near-Earth Asteroid(52760) 1998 ML14 Constraints from the 1998 and2013 ApparitionsOstro et al (Meteoritics amp Planetary Science 36 1225-1236 2001)

produced a shape model of the approximately 1-km diameternear-Earth asteroid (52760) 1998 ML14 using radar images takenwith the Arecibo and Goldstone planetary radar systems in 1998However the spin state (pole orientation and rotation period) wasnot well determined in their modelling The published shape modelwas produced using a 1483 h sidereal rotation period consistentwith the synodic period of 1498 plusmn 006 h found by opticalobservations in 1998 (Hicks amp Weissman IAU Circular 6987 11998) Optical observations in 2013 found a faster period of 1428 plusmn001 h (Warner The Minor Planet Bulletin 41 2 113-124 2014)Further radar observations at Arecibo in 2013 are inconsistent withthe 1483 h sidereal period Use of Arecibo radar images from bothapparitions with resolution as fine as 15 m per pixel are best fit bya sidereal period within 1 of 1428 h and constrain the poleorientation to within approximately ten degrees An updated shapemodel will be presented using this new information Theseimproved constraints illustrate the power of multiple apparitionsfor better determining the true shapes and spin states ofnear-Earth asteroids

Author(s) Benjamin N L Sharkey Patrick A Taylor Michael C Nolan Ellen S HowellInstitution(s) 1 Arecibo Observatory 2 LPLU Arizona 3University of Minnesota - Twin Cities

30808 ndash Arecibo and Goldstone Radar Observationsof the First-Recognized Binary Near-Earth Asteroid(385186) 1994 AW1Near-Earth asteroid (385186) 1994 AW1 was discovered at PalomarObservatory on 11 January 1994 Subsequent observations of thisAmor family Sa-class asteroid also identified it as the firstcandidate binary NEA as indicated by multiple periodicities andpossible mutual eclipsingocculting events in the objectrsquoslightcurve On 15 July 2015 this asteroid made its closest approachto Earth since its discovery coming within 0065 AU (25 lunardistances) and prompting an extended observation campaignusing both the JPL-Goldstone and Arecibo Observatory planetaryradars Goldstone observations covered the 14-19 July period ofclosest approach (0066-0070 AU) while the object remainedbelow Areciborsquos observing horizon with Arecibo picking up theobservations between 20-30 July as the object moved from 0075to 0126 AU distance At Goldstone we were able to observe thisobject with range resolutions of 150 m using a Goldstone (DSS-14)to Green Bank Telescope (GBT) bistatic configuration while atArecibo we conducted monostatic observations of 1994 AW1 usingthe 2380 MHz (126 cm) radar at resolutions of 30 m and 75 mAs a result and twenty years after its discovery these observationshave confirmed the binary nature of 1994 AW1 showing theprimary body to be about 600 m in diameter the secondary body tobe about half the diameter of the primary with the two orbiting acommon center of mass at a distance of about 12 km apart Delay-Doppler image comparisons of the primary over the course of sixnights (at 30 m resolution) confirm a lightcurve-derived rotationperiod of 2518 +- 0002 hr as gt90 longitude coverage wasachieved revealing a slightly elongated irregular surfacemorphology Delay-Doppler images of the secondary reveal anelongated irregular body which appears to be tidally locked withits long axis pointed towards the primary as it orbits with a period ofabout 22 hr (also consistent with the lightcurve analysis) Thesevery early results point to a total system mass of (16 +- 05) x10^11 kg and a crude mean system density estimate of 1400 +-500 kgm^3 Additional analysis and shape-modeling will bepresented

Author(s) James E Richardson Patrick A Taylor EdgardG Rivera-Valentin Linda A Rodriguez-Ford Lance AMBenner Shantanu P Naidu Jon D Giorgini Michael WBusch Frank d Ghigo Adam Kobelski Brian D Warner Alessondra Springmann Sean E Marshall Jordan K Steckloff Benjamin SharkeyInstitution(s) 1 Arecibo Observatory (USRA) 2 Center forSolar System Studies 3 Cornell University 4 Jet PropulsionLaboratory 5 National Radio Astronomy Observatory 6 PurdueUniversity 7 SETI Institute 8 University of Arizona 9University of Minnesota Twin Cities

1 1

1 1

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8 3 69

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30809 ndash LSSTrsquos Projected Near-Earth AsteroidDiscovery PerformanceThe Large Synoptic Survey Telescope (LSST) is an ambitiousproject that has the potential to make major advances inNear-Earth Asteroid search efforts With construction alreadyunderway and major optical elements complete first light is set for2020 followed by two years of commissioning Once regular surveyoperations begin in 2022 LSST will systematically survey theobservable sky over a ten-year period from its site on CerroPachon Chile With an 84 m aperture (65 m effective) 96 squaredegree field of view and a 32-Gigapixel camera LSST representsthe most capable asteroid survey instrument ever builtLSST will be able cover over 6000 square degrees of sky per clearnight with single visit exposures of 30 s reaching a faint limit of245 mag in the r band However the cadence of survey operationsis a critical factor for the near-Earth asteroid search performanceand there are multiple science drivers with different cadenceobjectives that are competing to shape the final survey strategy Weexamine the NEA search performance of various LSST searchstrategies paying particular attention to the challenges of linkinglarge numbers asteroid detections in the presence of noiseOur approach is to derive lists of synthetic detections for a giveninstantiation of the LSST survey based on an assumed model forthe populations of solar system objects from the main asteroid beltinwards to the near-Earth population These detection lists arecombined with false detection lists that model both random noiseand non-random artifacts resulting from image differencingalgorithms These large detection lists are fed to the Moving ObjectProcessing System (MOPS) which attempts to link the syntheticdetections correctly without becoming confused or overwhelmedby the false detectionsThe LSST baseline survey cadence relies primarily on single nightpairs of detections with roughly 30-60 min separating elements ofthe pair The strategy of using pairs is an aggressive and potentiallyfragile approach but theoretically represents the most productiveNEA search with the minimum impact on other LSST sciencedrivers

Author(s) Steven R Chesley Peter VerešInstitution(s) 1 JPL

30810 ndash The Mission Accessible Near-Earth ObjectSurvey (MANOS) mdash First ResultsThe Mission Accessible Near-Earth Object Survey (MANOS) beganin August 2013 as a multi-year physical characterization surveythat was awarded survey status by NOAO and has since expandedoperations to include facilities at Lowell Observatory and theUniversity of Hawaii MANOS will target several hundred mission-accessible NEOs across visible and near-infrared wavelengthsproviding a comprehensive catalog of physical properties(astrometry light curves spectra) Particular focus is paid tosub-km NEOs where little data currently exists These small bodiesare essential to understanding the link between meteorites andasteroids pose the most immediate impact hazard to the Earth andare highly relevant to a variety of planetary mission scenariosObserving these targets is enabled through a combination ofclassical queue and target-of-opportunity observations carried outat 1- to 8-meter class facilities in both the northern and southernhemispheres The MANOS observing strategy enables thecharacterization of roughly 10 of newly discovered NEOs beforethey fade beyond observational limitsTo date MANOS has obtained data on over 200 sub-km NEOs andwill ultimately provide major advances in our understanding of theNEO population as a whole and for specific objects of interest Herewe present first results from the survey including (1) the de-biasedtaxonomic distribution of spectral types for NEOs smaller than~100 meters (2) the distribution of rotational properties for smallobjects with high Earth-encounter probabilities (3) progress indeveloping a new set of online tools at asteroidlowelledu that willhelp to facilitate observational planning for the small body observercommunity and (4) physical properties derived from rotationallight curvesMANOS is supported through telescope allocations from NOAOLowell Observatory and the University of Hawaii We acknowledge

funding support from NASA NEOO grant number NNX14AN82Gand an NSF Astronomy and Astrophysics Postdoctoral Fellowshipto N Moskovitz

Author(s) Nicholas Moskovitz Louis Avner RichardBinzel Brian Burt Eric Christensen Francesca DeMeo MaryHinkle Michael Mommert Michael Person David Polishook Robert Schottland Hosea Siu Audrey Thirouin CristinaThomas David Trilling Lawrence Wasserman Mark WillmanInstitution(s) 1 CSSUA 2 Lowell Observatory 3 MIT 4Northern Arizona University 5 PSI 6 University of Hawaii 7Weizmann Institute of Science

30811 ndash Albedo Size and Taxonomy of the Small BodyPopulations Outside the Main BeltUsing the data from the WISENEOWISE mission we have derivedalbedo and size distributions of ~1200 Cybeles ~1000 Hildas~1700 Jovian Trojans and a dozen irregular satellites of Jupiter andSaturn These data increases by an order of magnitude ourknowledge of the makeup of the small body populations betweenthe Main Belt and Saturn We find that all these populations aredominated by low albedo objects with only the Cybeles (with lessthan 10) having any significant fraction of possible interloperobjects with albedo higher than 15 Using the near-infraredalbedos (in the 34 and 46μm bands denoted W1 and W2respectively) we were able to derive the taxonomic classifications ofthe largest objects in each population showing that they aredominated by surfaces that are similar to C- P- and D-typeasteroids The dominance of these dark primitive surfaces indicatetwo possible formation scenarios These small body populationsmay have been formed in situ beyond the snow line potentiallyserving as bodies that can provide significant insight into thecomposition of the early Solar Nebula in the region of the currentGiant Planets Alternatively they may be captured bodies that wereperturbed from the region outside the Giant Planets as the planetsmigrated during the early stages of Solar System formation Thisallows for insight into the composition of the Trans-Neptunianpopulation by study of populations that are significantly closerbrighter and more accessible The low percentages of potentiallyhigher albedo stony objects common in the Main Asteroid Beltindicates that only a few of these objects have embeddedthemselves into these populations potentially imposing significantconstraints on the migration of Jupiter inside its current orbit

Author(s) Tommy Grav Amy Mainzer James Bauer Joseph R Masiero Roc Cutri Carrie Nugent Sarah Sonnett Emily A KramerInstitution(s) 1 Infrared Processing and Analysis Center -California Institute of Technology 2 Jet Propulsion Laboratory 3Planetary Science Institute

30812 ndash Results from the LCOGT Near-Earth ObjectFollow-up NetworkLas Cumbres Observatory Global Telescope Network (LCOGT) hasdeployed a homogeneous telescope network of nine 1-meter andtwo 2-meter telescopes to five locations in the northern andsouthern hemispheres with plans to extend to twelve 1-metertelescopes at 6 locations The versitility and design of this networkallows for rapid response to target of opportunity events as well asthe long-term monitoring of slowly changing astronomicalphenomena The networks global coverage and the apertures oftelescopes available make LCOGT ideal for follow-up andcharacterization of Solar System objects (eg asteroids Kuiper BeltObjects comets Near-Earth Objects (NEOs)) and ultimately forthe discovery of new objectsLCOGT has completed the first phase of the deployment with theinstallation and commissioning of the nine 1-meter telescopes atMcDonald Observatory (Texas) Cerro Tololo (Chile) SAAO (SouthAfrica) and Siding Spring Observatory (Australia) This iscomplimented by the two 2-meter telescopes at Haleakala (Hawaii)and Siding Spring Observatory The telescope network has beenfully operational since May 2014 and observations are beingexecuted remotely and robotically Future expansion to sites in theCanary Islands and Tibet are planned for 2016

1 1

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86

The LCOGT near-Earth object group is using the network toconfirm newly detected NEO candidates produced by the major skysurveys such as Catalina Sky Survey (CSS) PanSTARRS (PS1) andNEOWISE with several hundred targets being followed per yearFollow-up astrometry and photometry of radar-targeted objectsand those on the Near-Earth Object Human Space FlightAccessible Targets Study (NHATS) or Asteroid Retrieval Mission(ARM) lists are improving orbits producing light curves androtation periods and better characterizing these NEOs Recentresults include the first period determinations for several of theGoldstone-targeted NEOs In addition we are in the process ofbuilding a NEO portal that will allow professionals amateurs andCitizen Scientists to plan schedule and analyze NEO imaging andspectroscopy observations and data using the LCOGT Network andto act as a coordination hub for the NEO follow-up efforts

Author(s) Sarah Greenstreet Tim Lister Edward Gomez Eric Christensen Steve LarsonInstitution(s) 1 Catalina Sky Survey 2 Las CumbresObservatory Global Telescope Network

30813 ndash Searching for a Differentiated AsteroidFamily A Spectral Survey of the Massalia Merxia andAgnia FamiliesAsteroid families were formed by catastrophic collisions or largecratering events that caused fragmentation of the parent body andejection of asteroidal fragments with velocities sufficient to preventre-accretion Due to these formation processes asteroid familiesshould provide us with the opportunity to probe the interiors of theformer parent bodies Differentiation of a large initially chondriticparent body is expected to result in an onion shell object with aniron-nickel core a thick olivine-dominated mantle and a thinplagioclasepyroxene crust However most asteroid families tendto show similar spectra (and therefore composition) among themembers Spectroscopic studies have observed a paucity ofmetal-like materials and olivine-dominated assemblages within theMain Belt asteroid familiesThe deficit of olivine-rich mantle material in the meteorite recordand in asteroid observations is known as the Missing Mantleproblem For years the best explanation has been the battered tobits hypothesis that all differentiated parent bodies (aside fromVesta) were disrupted very early in the Solar System and theresulting olivine-rich material was collisionally broken down overtime until the object diameters fell below our observational limitsIn a competing hypothesis Elkins-Tanton et al (2013) havesuggested that previous work has overestimated the amount ofolivine produced by the differentiation of a chondritic parent bodyWe are conducting a visible and near-infrared wavelength spectralsurvey of asteroids in the Massalia Merxia and Agnia S-type MainBelt asteroid families These families were carefully chosen for theproposed spectroscopic survey because they have compositionsmost closely associated with a history of thermal metamorphismand because they represent a range of collisional formationscenarios In addition the relatively young ages (under 400 Myr)of these families permit testing of the ldquobattering to bits timescaleWe will present initial results from our ongoing spectral survey ofthese three Main Belt families and discuss evidence fordifferentiation among the family membersWe acknowledge funding support from the NASA PlanetaryAstronomy program

Author(s) Cristina A Thomas Lucy Lim NicholasMoskovitz David TrillingInstitution(s) 1 Lowell Observatory 2 NASA GSFC 3 NASAGSFCUSRA 4 Northern Arizona University

30814 ndash Public Archiving and Curation of SpacewatchDataImage data from Spacewatchs astrometry of asteroids date back to1985 At this meeting we introduce data from the most voluminousmode of operation of Spacewatch to the web for public access Thesurvey with the Spacewatch 09-meter telescope has goodastrometric and photometric accuracy and revisits the same cohortsof main belt asteroids at 4-day intervals by migrating the telescope

pointings appropriately This pattern has made possiblemulti-night prediscovery detections (precoveries) of Near EarthObjects (NEOs) when they were distant slowly moving andtherefore originally unnoticed and is a similarly unique asset toother researches in the temporal domain Limiting V magnitude is20-215 and sky coverage is 1400 square degrees per lunationthree times per position This survey has been in operationuniformly with the same equipment and procedure from 2003 tothe present (2015) producing some 17 TB of imaging dataProcessing includes documentation of instrumental parametersbias subtraction flat-fielding defringing positional registrationastrometric mapping and indexing relevant image parameters to asearchable database Tools for finding images that contain movingobjects will be demonstrated at the meeting Examples ofapplications of these data are prediscovery observations of NEOsand comets to improve knowledge of the objects orbits Asteroidswhose orbits and albedos suggest that they might be dormantcomets can also be checked for cometary features Beyond the solarsystem the cadence of the Spacewatch mosaic data will providephotometric sampling of variable stars and galaxies on time scalesfrom tens of minutes to 12 years a range rarely available fromdatabases of this typeSupport of Spacewatch wasis from a JPL subcontract (2010-2011)NASANEOO grants the Lunar and Planetary Laboratory StewardObservatory Kitt Peak National Observatory the BrinsonFoundation of Chicago IL the estates of R S Vail and R LWaland and other private donors We are also indebted to theMPC and JPL for their web services

Author(s) Jeffrey A Larsen Robert S McMillan TerrenceH Bressi Ronald A Mastaler James V Scotti Andrew FTubbioloInstitution(s) 1 Lunar and Planetary Laboratory University ofArizona 2 US Naval Academy

30815 ndash Astrometric Results of NEOs from theCharacterization and Astrometric Follow-up Programat Adler PlanetariumWe present astrometric results of near-Earth objects (NEOs)targeted in fourth quarter 2014 and in 2015 This is part of AdlerPlanetariumrsquos NEO characterization and astrometric follow-upprogram which uses the Astrophysical Research Consortium(ARC) 35-m telescope at Apache Point Observatory (APO) Theprogram utilizes a 17 share of telescope time amounting to a totalof 500 hours per year This time is divided up into two hourobserving runs approximately every other night for astrometry andfrequent half-night runs approximately several times a month forspectroscopy (see poster by M Hammergren et al) and light curvestudies (see poster by M J Brucker et al)Observations were made using Seaver Prototype Imaging Camera(SPIcam) a visible-wavelength direct imaging CCD camera with2048 x 2048 pixels and a field of view of 478rsquo x 478rsquo Observationswere made using 2 x 2 binningSpecial emphasis has been made to focus on the smallest NEOsparticularly around 140m in diameter Targets were selected basedon absolute magnitude (prioritizing for those with H gt 25 mag toselect small objects) and a 3σ uncertainty less than 400rdquo to ensurethat the target is in the FOV Targets were drawn from the MinorPlanet Center (MPC) NEA Observing Planning Aid the JPL WhatrsquosObservable tool and the Spaceguard priority list and faint NEO listAs of August 2015 we have detected 670 NEOs for astrometricfollow-up on point with our goal of providing astrometry on athousand NEOs per year Astrometric calculations were done usingthe interactive software tool Astrometrica which is used for datareduction focusing on the minor bodies of the solar system Theprogram includes automatic reference star identification fromnew-generation star catalogs access to the complete MPC databaseof orbital elements and automatic moving object detection andidentificationThis work is based on observations done using the 35-m telescopeat Apache Point Observatory owned and operated by theAstrophysical Research Consortium We acknowledge the supportfrom the NASA NEOO award NNX14AL17G and thank theUniversity of Chicago Astronomy and Astrophysics Department for

2 2 21 1

3 21 4

2 11 1 11

87

observing time in 2014

Author(s) Kristie A Nault Melissa J Brucker MarkHammergren Geza Gyuk Mike R SolontoiInstitution(s) 1 Adler Planetarium 2 Lynchburg College

30816 ndash The Las Cumbres Observatory (LCOGT)Network for NEO and Solar System ScienceLas Cumbres Observatory Global Telescope Network (LCOGT) hasdeployed a homogeneous telescope network of nine 1-metertelescopes to four locations in the northern and southernhemispheres with a planned network size of twelve 1-metertelescopes at 6 locations This 1-meter network is in addition to thetwo 2-meter Faulkes Telescopes that have been operating since2005 This network is very versatile and is designed to respondrapidly to target of opportunity events and also to perform longterm monitoring of slowly changing astronomical phenomena Theglobal coverage of the network and the apertures of telescopeavailable make LCOGT ideal for follow-up and characterization ofSolar System objects eg Near-Earth Objects (NEOs) cometsasteroids and Kuiper Belt Objects and also for the discovery of newobjectsLCOGT has completed the first phase of the deployment with theinstallation and commissioning of the nine 1-meter telescopes atMcDonald Observatory (Texas) Cerro Tololo (Chile) SAAO (SouthAfrica) and Siding Spring Observatory (Australia) The telescopenetwork has been fully operational since 2014 May andobservations are being executed remotely and robotically Futureexpansion to sites in the Canary Islands and Tibet are planned for2016-2017I will describe the Solar System science research that is beingcarried out using the LCOGT Network with highlights from theLCOGT NEO Follow-up Network long-term monitoring of theRosetta spacecraft target comet 67P and comet C2013 A1 (SidingSpring) and work on Kuiper Belt Object occultation targetsincluding Pluto

Author(s) Tim Lister Sarah Greenstreet Edward Gomez Eric Christensen Stephen LarsonInstitution(s) 1 Las Cumbres Observatory 2 University ofArizona

30817 ndash Searching for dormant comets in the NEOregion using data from the Canadian Meteor OrbitRadarDormant comets (DCs) are objects that appear asteroidal but havecometary origins Earth-approaching DCs may produce dust duringtheir final active stages which potentially are detectable as weakmeteor showers at the Earth However identifying DCs is difficultas they are observationally indistinguishable from asteroids Pastasteroid-stream searches have produced some possible linkagesbetween asteroids and meteor showers the most notable being theGeminids and 3200 (Phaethon) and the Quadrantids and (196256)2003 EH1 However a comprehensive survey to look for allpossible weak streams from recent DC activity including dynamicalformation and evolution of early dust trails has yet to beperformed Here we report on the progress of a DC meteoroidstream survey whereby we have identified all DC candidates whoseorbits are such that recent (last several hundred years) dust releasewould be currently detectable at the Earth We have simulated theevolution of dust trails for all candidate DC-stream objects andgenerate predictions for the characteristics of the associated DCshower at Earth We then perform a cued survey for such streamsamong the 15 mega meteoroid orbits measured by CMOR since2002 using a wavelet-based search algorithm with probe sizestuned to the expected shower characteristics The search is focusedon ~300 Earth-approaching asteroids that have dynamicalcharacteristics of comets (or asteroids in cometary orbits ACOs)For some cases we will also discuss the connection between themeteor data and astrophysical observations of the parent bodyitself

Author(s) Quan-Zhi Ye Peter BrownInstitution(s) 1 The University of Western Ontario

30818 ndash Meteor shower forecast improvements froma survey of all-sky network observationsMeteoroid impacts are capable of damaging spacecraft andpotentially ending missions In order to help spacecraft programsmitigate these risks NASArsquos Meteoroid Environment Office (MEO)monitors and predicts meteoroid activity Temporal variations innear-Earth space are described by the MEOrsquos annual meteorshower forecast which is based on both past shower activity andmodel predictionsThe MEO and the University of Western Ontario operate sisternetworks of all-sky meteor cameras These networks have been inoperation for more than 7 years and have computed more than20000 meteor orbits Using these data we conduct a survey ofmeteor shower activity in the ldquofireballrdquo size regime using DBSCANFor each shower detected in our survey we compute the date ofpeak activity and characterize the growth and decay of the showerrsquosactivity before and after the peak These parameters are thenincorporated into the annual forecast for an improved treatment ofannual activity

Author(s) Althea V Moorhead Glenn Sugar Peter GBrown William J CookeInstitution(s) 1 NASA 2 Stanford University 3 University ofWestern Ontario

30819 ndash Status of The Catalina Sky SurveyThe Catalina Sky Survey (CSS) continues to be a key contributor toNASArsquos Near-Earth Object (NEO) survey effort accounting for 42of all new discoveries in the last calendar year (618 of 1478)Recent upgrades and improvements include the routine queue-scheduled remote operation of a 10-m telescope principallydedicated to the follow-up of newly discovered NEOsenhancement of the moving object detection software resulting in a10-15 increase in efficiency reduction in acquisition overheadsresulting in ~10 higher data throughput and changes to the datareduction pipeline which have yielded overall better data quality(flat-fielding astrometry and photometry) Significantinstrumentation upgrades to the 15-m telescope (MPC code G96)and 07-m Schmidt telescope (MPC code 703) are underwaydespite significant delays in procuring science-grade 10k x 10kdetectors The G96 camera has been fully assembled in the lab andon-sky commissioning is imminent When complete these newcameras will increase the fields-of-view of the 15-m and 07-m by40x (to 50 sq deg) and 24x (to 194 sq deg) dramaticallyexpanding the nightly coverage for both telescopesThe Catalina Sky Survey is funded by NASArsquos Near-Earth ObjectObservation program (NNX15AF79G)

Author(s) Eric J Christensen David Carson Fuls Alex RGibbs Albert D Grauer Rik E Hill Jess A Johnson Richard AKowalski Stephen M Larson Rose G Matheny Frank C ShellyInstitution(s) 1 The University of Arizona

30820 ndash A systematic search for undiscoveredcompanions to near-Earth asteroids in radar imagesRadar observations have been paramount to the characterization ofsmall (lt20 km) Near-Earth Objects (NEOs) specifically withregards to asteroid trajectories shapes spins and multi-component systems Binary systems make up a sizable fraction(~16) of the asteroid population in near-Earth space Theirformation process is understood to be rotational fission caused bythe YORP effect Possible outcomes of post-fission dynamicsinclude contact binaries tightly and loosely bound binaries andasteroid pairs Radar images have been used to identify asteroidsatellites that orbit near the primary component but relatively littleattention has been paid to the detection of more distant satellitesWe are conducting a systematic search for faint andor distantsatellites in the Arecibo radar data archive To this end we havedeveloped a software package to identify candidate objects in radarimages and to differentiate these candidates from backgroundnoise using statistical analysis preliminary results of the searchwill be presented at the meeting Possible future applicationsinclude systematic measurements of asteroid radar properties (egDoppler and range extents) that could become part of an

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88

automated data reduction pipeline

Author(s) M Oliver Bowman Jean-Luc MargotInstitution(s) 1 University of California Los Angeles

30821 ndash Serendipitous Observations of Asteroids bythe K2 MissionThe K2 mission is using the unique assets of the Kepler spacetelescope to perform long-baseline high-cadence high-precisionphotometry of targets selected by the community Unlike theoriginal Kepler mission the loss of two reaction wheels requires K2to point near the ecliptic plane As a result thousands of faintasteroids can be seen to pass through the target pixel masks thatare downlinked to earth after each ~75-day observing campaign Iwill show how these serendipitous observations of asteroids can beused to obtain lightcurves for faint (Vgt18) objects which areotherwise challenging to target from the ground In particular I willdemonstrate that the data are well-suited to identify small asteroidswith rotation periods near or below the ~2 hour spin barrier I willalso highlight the K2 data of other solar system bodies includingthe comets trans-Neptunian objects and Jupiter trojans for whichdedicated pixel masks have been (or will be) downlinked Owing toits ecliptic pointing and 14-meter diameter mirror K2 is offeringunique time-series photometry of small solar system bodies at aprecision which is unlikely to be rivaled by the future smaller-aperture photometric missions such as TESS and PLATO

Author(s) Geert BarentsenInstitution(s) 1 NASA Ames

309 ndash Formation of Planets Satellites andSmall Bodies30901 ndash Tidal Evolution of the Moon from aHigh-Obliquity Fast-Spinning EarthIn the conventional Giant Impact (GI) model of lunar formationthe Moon forms primarily from the debris of the impactor that islaunched into Earth orbit This is in conflict with extremelyEarth-like isotopic composition of the Moon All pre-2012 GImodels relied on the classic picture of lunar tidal evolution (egGoldreich 1965 Touma and Wisdom 1994) in which angularmomentum (AM) of the Earth-Moon system has been conservedsince lunar formation Cuk and Stewart (2012) showed that ahigh-AM Earth-Moon system can lose AM through the evectionresonance between the Moon and the Sun allowing for GIs that aremore conducive to incorporating Earth material into the MoonMore recently Lock et al (2015) show that a very-fast spinningEarth should be heavily coupled to the protolunar disk resulting inthe uniform composition of the Moon and Earths mantle Whilethe geophysical and geochemical benefits of the high-AM GI areclear further confirmation is needed that AM loss is both likely andconsistent with observed lunar orbit Not only does the evectionresonance not explain the current 5-degree lunar inclination butChen and Nimmo (2013) show that the conventional model oflunar spin evolution (Ward 1975) would lead to large-scaledamping of lunar inclination in the past The prospect of a pasthigh-inclination Moon requires complete revision of lunar tidalevolution models We use a numerical integrator that follows boththe orbit and the spin of the Moon and find that the Moon waslikely in non-synchronous rotation for a prolonged period duringCassini state transition implying inclination damping in excess ofthat in synchronous rotation We propose that the Moonscomposition and past large inclination can be explained by Earthspost-GI obliquity of about 70 degrees which led to instability oflunar orbit at the Laplace plane transition (Tremaine et al 2009)causing AM loss Earth obliquity reduction and lunar inclinationexcitation Subsequent secular resonance between Earths spin andthe Moons orbit further reduced Earths obliquity to its presentvalue

Author(s) Matija Cuk Sarah Stewart Simon Lock DouglasHamiltonInstitution(s) 1 Harvard U 2 SETI Institute 3 UC Davis 4University of Maryland

30902 ndash Dynamical Sequestration of theMoon-Forming Impactor in Co-Orbital Resonancewith EarthRecent concerns about the giant impact hypothesis for the origin ofthe moon and an associated ldquoisotope crisisrdquo are assuaged if theimpactor was a local object that formed near Earth and the impactoccurred relatively late We investigated a scenario that may meetthese criteria with the moon-forming impactor originating in 11co-orbital resonance with Earth Using N-body numericalsimulations we explored the dynamical consequences of placingMars-mass companions in various co-orbital configurations with aproto-Earth having 90 of its current mass We modeledconfigurations that include the four terrestrial planets as well asconfigurations that also include the four giant planets In both the4- and 8-planet models we found that a single additionalMars-mass companion typically remains a stable co-orbital ofEarth for the entire 250 million year (Myr) duration of oursimulations (33 of 34 simulations) In an effort to destabilize sucha system we carried out an additional 45 simulations that includeda second Mars-mass co-orbital companion Even with twoMars-mass companions sharing Earthrsquos orbit most of these models(28) also remained stable for the entire 250 Myr duration of thesimulations Of the 17 two-companion models that eventuallybecame unstable 12 impacts were observed between Earth and anescaping co-orbital companion The average delay we observed foran impact of a Mars-mass companion with Earth was 101 Myr andthe longest delay was 221 Myr Several of the stable simulationsinvolved unusual 3-planet co-orbital configurations that couldexhibit interesting observational signatures in plantetary transitsurveys

Author(s) Stephen J Kortenkamp William J HartmannInstitution(s) 1 Planetary Science Institute

30903 ndashThermal History and Volatile Partitioning betweenProto-Atmosphere and Interior of Mars Accreted in aSolar NebulaRecent precise Hf-W chronometry of Martian meteorites revealsthat Mars had likely reached the half of its present mass within 3Myr from the birth of the solar system (Dauphas and Pourmand2011) Hence the accretion is considered to almost proceed withinthe solar nebula associated with the capture of nebula gascomponents At the same time the impact degassing mayinevitably occur because impact velocity increases high enough forsuch degassing when a proto-planet gets larger than around lunarsize Thus we can expect the formation of a hybrid-type proto-atmosphere that consists of nebula gas and degassed oneThis study analyzes the thermal structure of this proto-atmospheresustained by accretional heating by building a 1D radiative-convective equilibrium model Raw materials of Mars are supposedto be volatile-rich on the basis of the geochemical systematics ofMars meteorites (Dreibus and Wanke 1988) The composition ofdegassed component comprised of H H O CH and CO isdetermined by chemical equilibrium with silicate and metal underthe physical condition of locally heated region generated by eachimpact (Kuramoto 1997) Degassed component lies beneath thenebula gas atmosphere at altitudes below the compositionalboundary height that would change depending on the amount ofdegassed component The accretion time is taken to be from 1 to 6MyrOur model predicts that the surface temperature exceeds theliquidus temperature of rock when a proto Mars grows larger than07 times of its present mass for the longest accretion time case Inthis case the magma ocean mass just after the end of accretion is02 times of its present mass if heat transfer and heat sources suchas short-lived radionuclides are neglected in the interior Thecorresponding amount of water dissolved into the magma oceanwould be around 18 times the present Earth ocean mass These

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results suggest that the earliest Mars would be hot enough to formdeep magma oceans which promotes the core-mantledifferentiation and wet sufficient to make a deep-water ocean

Author(s) Hiroaki Saito Kiyoshi KuramotoInstitution(s) 1 Hokkaido University

30904 ndash Energy Dissipation in the Full N-BodyProblemWhen accounting for the dissipation of energy systems of finitedensity particles may achieve minimum energy resting states thatare unattainable in the classic point-mass treatment of the N-BodyProblem These aggregates serve as a model for rubble pileasteroids protoplanetary disk grains and planetary ring particlesAnalytical studies have shown all relative equilibria both stableand unstable as functions of angular momentum and energy forfew-N systems of spheres this approach likely applies to larger-Nsystems with mathematical and topological complexity increasingwith N and with the geometrical complexity of the constituentsUsing these studies as a guideline we simulate thousands ofrandomly generated small-N systems in order to determine thelikelihood of achieving one resting configuration over anotherprovided that multiple minimum energy configurations exist for aconstant angular momentum By restricting our aggregates to rigidparticles whose size is small enough to not compromise the rigidityof component bodies our study effectively probes the dynamical-mechanical properties of a wide array of small solar systemaggregates We outline the effects of energy dissipation on suchsystems primarily the effects of the coefficient of restitution whosevalue is the cumulative sum of mechanical deformations due toimpact in order to shed light on the early evolution of rubble-pilebodies

Author(s) Travis SJ Gabriel Daniel J ScheeresInstitution(s) 1 University of Colorado Boulder

30905 ndash Accretion of Cometary Nuclei in the SolarNebula Boulders Not PebblesComets are the most primitive bodies in the solar system Theyretain a largely unprocessed record of conditions in the primordialsolar nebula 456 Gyr ago including the initial accretion of dustand ice particles into macroscopic bodies Current accretion theorysuggests that ice and dust aggregates grew to pebble (cm) sizesbefore streaming instabilities and gravitational collapse broughtthese pebble swarms together as km-sized (or larger) bodiesRecent imaging of the nucleus of comet 67PChuryumov-Gerasimenko by the Rosetta OSIRIS camera team has revealed theexistence of ldquogoose bumprdquo terrain on the nucleus surface and liningthe interior walls of large ~200 m diameter and 180 m deepcylindrical pits These pits are believed to be sinkholes formedwhen near-surface materials collapse into voids within the nucleusrevealing the fresh comet interior on the walls of the pits Thegoose bump terrain consists of 3-4 m diameter ldquobouldersrdquorandomly stacked one on top of another We propose that theseboulders likely with an icy-conglomerate composition are thebasic building blocks of cometary nuclei This is the firstobservational confirmation of current accretion theories with thecaveat that rather than pebbles the preferred size range is 3-4 mboulders for objects formed in the giant planets region of the solarsystem The presence of icy grains beyond the solar nebulasnow-line and the large heliocentric range of the giant planetsregion likely contribute to the formation of these larger bouldersbefore they are incorporated into cometary nuclei This work wassupported by NASA through the US Rosetta Project

Author(s) Paul R Weissman Michael AHearnInstitution(s) 1 Planetary Science Institute 2 University ofMaryland

30906 ndash Formation of giant planetsrsquo cores by classicalplanetesimal accretionIn the core accretion scenario for formation of giant planetssolid-cores each with a roughly ten Earth masses first formfollowed by gravitational capture of massive gaseous envelopes

Although recent models favor solid core growth by accretion ofcentimeter-sized pebbles classical models in which embryos growby accretion of km-sized planetesimals have not been fullyunderstood We perform a suite of simulations for accretion ofsolid cores using a particle-based hybrid code that we have recentlydeveloped (Morishima 2015 Icarus 260 368) The code uses anN-body routine for interactions with planetary embryos while alarge number of small planetesimals are represented by a smallnumber of tracers and tracerndashtracer interactions are handled by astatistical routine The initial surface densities of both solid and gasare assumed to be seven times the minimum mass solar nebulaThe initial planetesimal size r_0 is varied from 100 m to 100 kmCollisions are assumed to result in either merging or hit-and-runbouncing depending on impact velocity (Genda et al 2012) whilefragmentation is ignored We find that embryos cannot usuallygrow to 10 Earth masses within 2 Myr although it can happen insome cases For the case of r_0 = 100 m embryos can grow up to6-7 Earth masses although they are quickly pushed toward thecentral star by planetesimals For r_0 = 100 km embryo massescan reach only two Earth masses within 2 Myr at best as theirgrowth is slow The case of r_0 = 1 km is found to be mostpromising as growth of embryos is fast while their inwardmigration is not very rapid

Author(s) Ryuji MorishimaInstitution(s) 1 University of California Los Angeles

30907 ndash Two- and Three-dimensional simulations ofatmospheric erosion by impactsOne of the key features of Earth-sized planets in this and othersystems is the presence or absence of an atmosphere Amechanism for atmsopheric loss post-formation is erosion byhypervelocity impacts by massive objects We are carrying outsimulations of the effects of hypervelocity impacts with the aim ofassessing the efficiency of the process and disentangling the effectsof impact erosion from other mechanisms such as thermal escapeFor our overall project we consider three types of planetsMars-type Earth-type and a super-Earth (8 M_earth) Surfaceatmospheric pressures are 1 10 and 100 bars Three diameters ofimpactors are considered (46 17 and 368 km) with impactvelocities of 2 4 6 and 8 times the escape velocity of the targetImpact simulations can be divided between local and globalcases depending on the geometry of the impact chiefly theimpactor size relative to the target planet and the depth of theatmosphere compared to the planets radius The calculationsdiscussed here are local the curvature of the planet and the radialdependence of the gravitational field are neglected The impactsimulations are carried out with the CTH code developed at SandiaNational Laboratory CTH is a highly advanced code widely used inthe planetary science community It utilizes adaptive meshrefinement to concentrate computational resources at locations ofphysical interest in the simulation such as shockfronts andmaterial interfaces It makes use of material strength models andadvanced tabular equations of state such as ANEOS and theSESAME library Post-impact analysis yields fluxes of materialmoving at escape speed or faster through the boundaries (chieflythe upper boundary at the exobase) we integrate the flux to get thetotal amount of escaping material Although we track three kinds ofmaterial (impactor target surface atmosphere) here we reportonly on the last (escaping atmosphere) We will present resultsfrom 2D and 3D simulations of impacts primarily for the largestimpactor (368 km diameter) This work was supported by NASAPlanetary Atmospheres Program award NNX14AJ45GComputations were carried out on the NASA Pleiades NAS clusterat NASA Ames

Author(s) D G Korycansky Kevin J Zahnle David CCatlingInstitution(s) 1 NASA Ames Reseatch Center 2 University ofCalifornia Santa Cruz 3 University of Washington

30908 ndash An experimental path to constraining theorigin of Jupiterrsquos Trojan asteroids by identifyingchemical fingerprints

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We present an experimental study aimed at exploring thehypothesis suggested by recent dynamical models ndash that theJupiter Trojan asteroids originated in the outer solar system werescattered by the same instability responsibility for the radicalrearrangement of the giant planets and were subsequentlycaptured in their current location (eg Morbidelli et al 2005Nesvorny et al 2013) We seek to identify spectroscopic chemicaland isotopic properties that can tie the Trojan populations to theseevolutionary pathways providing experimental support ofdynamical models and providing testable hypotheses that can feedinto the design of experiments that might be performed onpotential future missions to these and other primitive bodiesWe present the results of experiments devised to explore thehypothesis that Kuiper Belt Objects (KBOs) represent the parentpopulations of the Trojan asteroids Numerous thin ice filmscomposed of select solar system volatiles (H O H S CH OHNH ) were grown in various mixtures to simulate compositionalchanges of icy bodies as a function of volatility and radial distanceof formation from the Sun Subsequent processing of these icybodies was simulated using electron irradiation and heating Visiblereflectance spectra show significant reddening when H S ispresent Mid-infrared spectra confirm the formation of non-volatilesulfur-containing molecules in the products of H S-containingices These experiments suggest that the presence of specificsulfur-bearing chemical species may play an important role in thecolors of both the KBOs and Trojans today Finally we discuss therole of the silicate component expected on the surface of the Trojanasteroids (Emery et al 2006) and the implications of a surfacecomposed of silicates in intimate contact with the nonvolatileorganic residues generated by ice irradiationThis work has been supported by the Keck Institute for SpaceStudies (KISS) The research described here was carried out at theJet Propulsion Laboratory Caltech under a contract with theNational Aeronautics and Space Administration (NASA) and at theCaltech Division of Geological and Planetary Sciences

Author(s) Jordana Blacksberg Ahmed Mahjoub MichaelPoston Mike Brown John Eiler Bethany Ehlmann KevinHand Robert W Carlson Robert Hodyss Ian WongInstitution(s) 1 California Institute of Technology 2 JetPropulsion Laboratory

30909 ndash Into coldness Where CO ice collisions ruleplanet formationIn protoplanetary disks CO appears in solid state beyond itssnowline at 10AU Being highly abundant it can affect theproperties of collisional growth in this region of the diskIn this work we carried out laboratory collision experiments with~100μm CO ice particles and a wall covered with a CO ice layer at80K Collision velocities varied between 0 - 25 msWe measured the threshold velocity of 004ms between stickingand bouncing and found onset of fragmentation for velocitiesabove 075ms Furthermore we deduced models for the coefficientof restitution and the fragmentation strength which are consistentwith the experimental dataWe conclude that CO ice shows a similar collisional behavior assilicate dust Compared to H O ice the sticking velocity is an orderof magnitude smaller One consequence is the loss of any bdquostickingadvantageldquo for H O ice particles if they are mantled with CO iceand planetesimal growth might be preferred in the zone betweenthe H O snowline and the CO snowline

Author(s) Grzegorz Musiolik Jens Teiser Tim Jankowski Gerhard WurmInstitution(s) 1 Universitaumlt Duisburg-Essen

30910 ndash Origin of the ices agglomerated by Comet67PChuryumov-GerasimenkoThe nature of the icy material accreted by comets during theirformation in the outer regions of the protosolar nebula is a majoropen question in planetary science Some scenarios of cometformation predict that these bodies agglomerated from clathratescrystallized in the protosolar nebula Concurrently alternativescenarios suggest that comets accreted amorphous ice originating

from the interstellar cloud Here we show that the recent N2COand ArCO ratios measured in the coma of the Jupiter family comet67PChuryumov-Gerasimenko by the ROSINA instrument aboardthe European Space Agencys Rosetta spacecraft can helpdisentangling between these two scenarios

Author(s) Olivier Mousis Jonathan I Lunine AdriennLuspay-Kuti Tristan Guillot Bernard Marty Peter Wurz Mohamad Ali-Dib Kathrin Altwegg Myrtha Haumlssig MartinRubin Pierre Vernazza Jack H WaiteInstitution(s) 1 Cornell University 2 CRPG-CNRS Universiteacutede Lorraine 3 Laboratoire dAstrophysique de Marseille 4Observatoire de la Cocircte dAzur 5 SWRI 6 Universiteacute de Franche-Comteacute 7 University of Bern

30911 ndash Comet missions and what can still be donefrom groundMuch of the knowledge on comet nuclei that has become availablesince the 1PHalley encounters in 1986 is based on spacemissions The nucleus shape and some surface parameters(topography morphology thermal optical behaviourcomposition) can directly be determined through remote-sensingmeasurements at close encounters At present 8 comets have beenvisited The information that became available from these missionsis discussed in view to its relevance for understanding solar systemformation Emphasis is put on comets 81PWild-2 9PTempel103Hartley-3 and 67PChuryumov-Gerasimenko Furthermoreoptions and prospects are discussed on how to benefit moreeffectively from spacecraft data If the knowledge coming fromspacecraft data is properly transferred to other comets it willprovide new means to distinguish whether differences betweencomets observed in the coma reflect differences of the nucleus orare related to different environmental conditions of the comets atthe time of observation This in turn has important implications tothe question of how and where comets were formed in the earlysolar system Some unknowns can only be addressed if data exist ofa statistically relevant number of comets hence may remain openfor a rather long time Options will be discussed on how toapproach these questions in the future

Author(s) Rita SchulzInstitution(s) 1 ESA Scientific Support Office

310 ndash Titans Surface and Atmosphere31001 ndash Geologic Conditions Required for the FluvialErosion of Titanrsquos CratersIn comparison to other icy satellites Titan has a small number ofimpact craters on its surface This suggests that it has a youngsurface andor erosional processes that remove craters from itssurface The set of geological conditions on Titan that would allowcraters to become unrecognizable by orbiting spacecraft such asCassini is unclear Initial results suggest that not all geologicconditions would allow for complete degradation of impact craterson Titan Using a landscape evolution model we explored a largerparameter space to determine the conditions under which arepresentative 40 km crater on Titan would be eroded We focusedon varying the values of parameters such as bedrock and regolitherodibility sediment grain size the weathering rate of the regolithand whether or not the regolith was saturated with liquidhydrocarbons We found that only after changing the saturationstate of the regolith mid-way through the simulation was it possibleto completely erode the crater Since there are few craters on Titanthis suggests that during Titanrsquos geological history there may havebeen varying quantities of liquid on its surface Titan is known tohave a dense atmosphere not unlike that of the Earth that couldallow for surface liquids to vary under a changing climate Theerosion rate could then also vary as a direct result of changingclimatic conditions

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Author(s) Rebeca Kinser Catherine Neish Alan Howard Paul Schenk Veronica BrayInstitution(s) 1 Florida Institute of Technology 2 Lunar andPlanetary Institute 3 University of Arizona 4 University ofVirginia 5 University of Western Ontario

31002 ndash Usefulness and Limitations of EnergyLimited Escape Titan and Other PlanetaryAtmospheresBecause thermal conduction and IR cooling are inefficient heattransfer processes adiabatic expansion leading to molecular escapeis often the dominant cooling process for energy deposited in theupper atmosphere of planetary bodies This led to the use of theenergy-limited escape (EL) approximation in which the loss rate isroughly proportional to the heating rate Q In applying the ELapproximation it was also frequently assumed that the adiabaticexpansion resulted in the gas outflow going sonic Johnson et al(2013) used molecular kinetic simulations of an atmosphere with aheated layer to show this was not necessarily the case andestimated a critical heating rate Q For Q greater than ~Q a sonicpoint formed below the exobase where the gas properties werecollision dominated As Q increased above ~Q sonic escape waseventually limited by the energy and number fluxes from the belowthe heated layer In that case adiabatic cooling did dominate upperatmosphere cooling but the escape rate did not increase withincreasing Q as predicted by the EL model Instead the escape rateremained nearly constant and the energy per molecule carried offincreased nearly monotonically with Q For heating rates fromabout twice Q to more than an order of magnitude lower themolecular escape rate was well approximated by the energy limitedrate but the upper atmospheric structure could not be described bya fluid model with a sonic point and escape was Jeans-like althoughthe Jeans expressions was often a poor approximation That ismolecules escape from well below the nominal exobase andcollisions remained important well above it (Tucker et al 20092013) resulting in enhanced-Jeans-like escape (Volkov et al2011ab Erwin et al 2013) Here we give a new expression for theescape rate produced by adiabatic cooling and expansion of theupper atmosphere and apply it to atmospheric loss from an earlyTitan atmosphere and related atmospheresRef ErwinJT et alIcarus 226375(2013)JohnsonRE etalApJL768 L4(6pp)ErratApJL77490(2013) TuckerOJ et alPSS571889 (2009) TuckerOJ et alIcarus 222149(2013)VolkovAN et alApJLett729L24(5pp)(2011a) ibid Phys Fluids23(2011b)

Author(s) Robert E Johnson Alexey N Volkov Orenthal JTuckerInstitution(s) 1 Univ of Virginia 2 University of Alabama 3University of Michigan

31003 ndash Titans Seasonal Haze Variation fromHST-STIS Image CubesFive STIS image cubes of Titan taken between 1997 and 2004constrain Titans seasonal haze variations during the season beforethe arrival of Cassini Each image cubes contains wavelengths530-1020 nm at 05 nm sampling with up to 005 arc-sec samplingin both spatial dimensions By comparing reflectivities betweendifferent dates stepping from the continuum wavelengths intomethane bands we determined the changing physical parametersand the size and phase of the variation including its altitudeWhile Titans north-south asymmetry is well know to change withTitans seasons HST and VIMS data showed its phasing to bespectrally dependent suggesting that the asymmetry does notchange simultaneously at all altitudesOur principal component analysis of the STIS cubes revealed thatthe north-south asymmetry is separated in two distinctcomponents a larger component describing changes at altitudesbelow 80+-20 km and a smaller component describing changes ataltitudes above 150+-50 km Altitudes in between did not showany change at any latitudeBoth components have a different phasing explaining phase shiftswith wavelengths noted above The high-altitude componentswitched the hemispherical asymmetry in 2001 The low-altitude

component had a rolling asymmetry change in 2002 at lowaltitudes in 2003 at mid latitude and in early 2004 at highaltitudesBoth components are due to variations of the aerosol opacity thatare probably driven by global dynamics The first component mayalso be partially due to a variation in the aerosol phase function andaerosol size which may be due to variable condensation of gasessuch as HCN onto aerosolsEquatorial latitudes have above average haze opacities at highaltitudes but below average at low altitudesA new haze model gives the haze opacity as function of altitudelatitude and time and fits the HST data well and even fits someCassini results obtained after the HST observations fairly well Itpredicts the next hemispherical asymmetry switch to occur in 2016at high altitudes and 2017 through 2018 at low altitudesDeails are currently being published in the Icarus special issue onTitan This research was supported by STScI through programAR12624

Author(s) Erich KarkoschkaInstitution(s) 1 Univ of Arizona

31004 ndash Titans aerosol optical properties with VIMSobservations at the limb of TitanThe study of Titan properties with remote sensing relies on a goodknowledge of the atmosphere properties The in-situ observationsmade by Huygens combined with recent advances in the definitionof methane properties enable to model and interpret observationswith a very good accuracy Thanks to these progresses we cananalyze in this work the observations made at the limb of Titan inorder to retrieve information on the haze properties as its verticalprofiles but also the spectral behaviour between 088 and 52 μmTo study the haze layer and more generally the source of opacitiesin the stratosphere we use som observation made at the limbe ofTitan by the VIMS instrument onboard Cassini We used a modelin spherical geometry and in single scattering and we accountedfor the multiple scattering with a parallel plane model that evaluatethe multiple scattering source function at the plane of the limbOur scope is to retrieve informations about the vertical distributionof the haze its spectral properties but also to obtain details aboutthe shape of the methane windows to disantangle the role of themethane and of the aerosolsWe started our study at the latitude of 55degN with a image taken in2006 with a relatively high spatial resolution (for VIMS) Ourpreliminary results shows the spectral properties of the aerosols arethe same whatever the altitude This is a consequence of the largescale mixing From limb profile between 09 and 52 μm we canprobe the haze layer from about 500 km (at 09 μm) to the ground(at 52 μm) We find that the vertical profile of the haze layer showsthree distinct scale heights with transitions around 250 km and350 km We also clearly a transition around 70-90 km that may bedue to the top of a condensation layer

Author(s) Pascal Rannou Benoit Seignovert PanayotisLavvas Steacutephane Lemouelic Christophe SotinInstitution(s) 1 JPLNASA 2 LPGNUniversiteacute de Nantes 3University of Reims-Champagne Ardenne

31005 ndash Microphysical Modeling of Titans DetachedHaze Layer in a 3D GCMWe investigate the formation and seasonal cycle of the detachedhaze layer in Titanrsquos upper atmosphere using a 3D GCM withcoupled aerosol microphysics The base of the detached haze layeris defined by a local minimum in the vertical extinction profile Thedetached haze is seen at all latitudes including the south pole asseen in Cassini images from 2005ndash2012 The layer merges into thewinter polar haze at high latitudes where the Hadley circulationcarries the particles downward The hemisphere in which the hazemerges with the polar haze varies with season We find that thebase of the detached haze layer occurs where there is a nearbalance between vertical winds and particle fall velocities Generallythe vertical variation of particle concentration in the detached hazeregion is simply controlled by sedimentation so the concentrationand the extinction vary roughly in proportion to air density This

1 5 42 3

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92

variation explains why the upper part of the main haze layer andthe bulk of the detached haze layer follow exponential profilesHowever the shape of the profile is modified in regions where thevertical wind velocity is comparable to the particle fall velocity Oursimulations closely match the period when the base of the detachedlayer in the tropics is observed to begin its seasonal drop in altitudeand the total range of the altitude drop However the simulationshave the base of the detached layer about 100 km lower thanobserved and the time for the base to descend is slower in thesimulations than observed These differences may point to themodel having somewhat lower vertical winds than occur on Titanor somewhat too large of particle sizes or some combination ofboth Our model is consistent with a dynamical origin for thedetached haze rather than a chemical or microphysical one Thisbalance between the vertical wind and particle fall velocities occursthroughout the summer hemisphere and tropics The particleconcentration gradients that are established in the summerhemisphere are transported to the winter hemisphere bymeridional winds from the overturning Hadley cell Our model isconsistent with the disappearance of the detached haze layer inearly 2014

Author(s) Erik J Larson Owen B Toon Robert A West AJames FriedsonInstitution(s) 1 Jet Propulsion Laboratory 2 University ofColorado

31006 ndash Comparing the Treatment of Spherical andFractal Particles in Titanrsquos Atmosphere using CARMAThe nature of Titanrsquos optically thick haze is of great interest in thestudy of its atmosphere In an attempt to further understand theparticle distribution and radiative properties of this haze we appliedthe Community Aerosol and Radiation Model for Atmospheres(CARMA) originally designed for Earth to simulate themicrophysical and radiative transfer properties of Titanrsquosatmosphere In the past the model treated the haze particles asspheres however it is more accurate to treat the haze particles asfractals (Lavvas et al 2010) We first simulated spherical particlesto verify the modelrsquos consistency with past studies (ie Toon et al1992) We then ran simulations considering fractal haze particlesIn both instances we considered a 600km atmosphere with aproduction zone centered at 300km from the surface Theseparticles initially 00013 microm in radius are then subject to verticaltransport and coagulation processes affecting the size number anddistribution of the particles Our results for both cases show thatfor wavelengths of 550nm the optical depth and extinction of theatmosphere rapidly decreases above 400km however there is agreater concentration of fractal particles at altitudes above 400kmthan spherical particles by at least two orders of magnitude Initialresults indicate that above 400km there were approximately 2x10fractal particlescm whereas there were only at most 1x10spherical particlescm corresponding with a greater cumulativeoptical depth of Titanrsquos atmosphere for fractal particles thanspherical particles The full effects of these results on thecumulative optical depth of the atmosphere are still being exploredThis work was funded by the NASA Outer Planets researchprogram

Author(s) Alexander Lanzano Erika BarthInstitution(s) 1 Laboratory for Atmospheric and Space Physics2 Southwest Research Institute

31007 ndash Soundings of Titans atmosphere by Cassiniusing the two-way radio occultation techniqueIn December 2011 the Ultra Stable Oscillator aboard Cassini failedand all subsequent radio occultations have been done using thetwo-way technique The two-way technique uses a highly stablefrequency reference on the ground rather than the on board USOA pure X band tone is transmitted to the spacecraft and that uplinksignal as Cassini receives it is used as the frequency reference forthe three returned S X and Ka band tones transmitted by thespacecraft On May 17 and June 18 of 2014 two occultations ofCassini by Titan occured during targeted Titan encounters T101and T102 and were done using the two-way technique for the first

time for Titan occultations We present the four soundings ofTitans atmosphere obtained from the resulting data using the twoway numerical inversion technique described in Schinder et alRadio Science 50 712 The ingress occultation on T101 occured at66 N latitude and egress is at 46 S On T102 ingress occured at 63N and 66 S latitude We will also place these results in context withthe earlier Titan occultations (Schinder et al Icarus 215 460Schinder et al Icarus 221 1020) done in one way mode

Author(s) Paul J Schinder F Michael Flasar EssamMarouf Richard French Aseel Anabtawi Elias BarbinisInstitution(s) 1 Cornell Univ 2 Jet Propulsion Laboratory 3NASA Goddard Space Flight Center 4 San Jose State University5 Wellesley College

31008 ndash Seasonal variations of temperature andcomposition at the Titan polesWe present an analysis of spectra acquired by CassiniCIRS at highresolution from October 2010 until September 2014 in nadir mode([1] amp refs therein) Since 2010 we have observed the appearance atTitanrsquos south pole of several trace species for the first time such asHC N and C H observed only at high northern latitudes beforeequinox We investigate here latitudes poleward of 50degS and 50degNfrom 2010 (after the Southern Autumnal Equinox) until 2014 Forsome of the most abundant and longest-lived hydrocarbons(C H C H and C H ) and CO the evolution in the past 4years at a given latitude is not significant within error bars untilmid-2013 More recently these molecules show a trend forincrease in the south This trend is dramatically more pronouncedfor the other trace species especially in 2013-2014 and at 70degSrelative to 50degS These two regions then demonstrate that they aresubject to different dynamical processes in and out of the polarvortex region For most species we find higher abundances at50degN compared to 50degS with the exception of C H CO C Hand HC N which arrive at similar mixing ratios after mid-2013While the 70degN data show generally no change except a smalldecrease for most species within 2014 the 70degS results indicate astrong enhancement in trace stratospheric gases after 2012 The663 cm HC N and the C H 674 cm emission bands appearedin late 2011early 2012 in the south polar regions and have sincethen exhibited a dramatic increase in their abundances At 70degSHC N HCN and C H have increased by 3 orders of magnitudeover the past 3-4 years while other molecules including C H C H and C H have increased less sharply (by 1-2 orders ofmagnitude) This is a strong indication of the rapid and suddenbuildup of the gaseous inventory in the southern stratosphereduring 2013-2014 as expected as the pole moves deeper intowinter shadow Subsiding gases that accumulate in the absence ofultraviolet sunlight evidently increased quickly since 2012 andsome of them may also be responsible for the reported hazedecrease in the north and its appearance in the south at the sametimeReference [1] Coustenis et al 2015 Icarus doi101016jicarus201508027

Author(s) Athena Coustenis Donald E Jennings RichardK Achterberg Georgios Bampasidis Panayiotis Lavvas ConorA Nixon Nicholas A Teanby Valeria Cottini Carrie MAnderson F Michael FlasarInstitution(s) 1 Faculty of Physics National and KapodistrianUniversity of Athens 2 GSMA Universiteacute Reims Champagne-Ardenne 3 Laboratoire drsquoEtudes Spatiales et drsquoInstrumentation enAstrophysique (LESIA) Observatoire de Paris PSL-ResearchUniv CNRS Univ Pierre et Marie Curie Paris 06 SorbonneUniv Univ Paris-Diderot 4 NASA Goddard Space Flight Center5 School of Earth Sciences University of Bristol

31009 ndash Titans Gas Behavior During the South PoleFallTitanrsquos southern middle atmosphere has been showing severalchanges since the start of fall season in 2009 In 2012 a large cloudappeared [1] [2] [3] temperatures became very low andcondensation and gas concentration at the South Pole increased[3] [4]

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In this work we will show the results of gas abundances retrievalsin the South Pole and their latitudinal variation changes as the coldseason evolved with timeWe analyzed several Cassini Composite InfraRed Spectrometer(CIRS [5]) mid-infrared observations of the South Pole acquiredduring 2013-2014 The data coordinates were converted in order tobe centered on the atmospheric pole and refer to the 1 mbar leveland not to the surface We first determine stratospherictemperatures from the same data and latitudes from the n band ofmethane centered around 1300 cm We retrieve the temperatureprofiles applying a radiative transfer forward model combined witha non-linear optimal estimation inversion method [6] We thenretrieve the main gases abundances and track their variation withlatitude using the same methodLatitudinal changes of the main Titanrsquos gases - HC N C H C H C H C H C H and HCN - show different trends in theSouthern polar regions over 2014 when winter was getting closerWe observe a ring-shape in some of the gas abundancedistributions with a local maximum peak around -75 deg oflatitude We also observe an increase of abundance of most of thegases toward the south pole as seen previously in the North duringthe winter The observed increase of benzene over the South Pole isdefinitely evident and strong References [1] West R A et al(2013) BAAS 45 30503 [2] Jennings D E et al (2012) ApJ 754L3 [3] de Kok R et al (2014) Nature 514 7520 65-67 [4]Vinatier S et al (2015) Icarus Volume 250 p 95-115 [5] Flasar etal (2004) Space Sci Rev 115 169ndash297 [6] Irwin PGJ et al(2008) J Quant Spectrosc Radiat Trans 109 1136ndash1150

Author(s) Valeria Cottini Conor A Nixon Richard KAchterberg Donald E Jennings Nicolas Gorius Patrick G JIrwinInstitution(s) 1 Catholic University of America 2 NASA GSFC3 University of Maryland 4 University of Oxford

31010 ndash Seasonal evolution of tropospheric H onTitan from the Cassini CIRS investigationFar-infrared Titan spectra obtained with the Composite Infra-RedSpectrometer on the Cassini spacecraft have been analyzed to studythe latitude distribution of H in the troposphere as well as itstemporal evolution over the period from March 2007 to August2014 This analysis shows that the previously observeddistribution characterized by a 30-70 enhancement at highNorthern latitudes has become more symmetrical since EquinoxHence the reversed pole-to-pole Hadley cell circulationestablished shortly after Equinox has been effective in equilibratingthe H mole fraction in both polar regions although not effectiveenough to produce a reversal of the polar enhancements probablybecause of a long time constant for the transport of air masses fromthe stratosphere to the troposhere

Author(s) Reacutegis CourtinInstitution(s) 1 LESIA - Observatoire de Paris

31011 ndash The Non-LTE Model of IR Emissions ofMethane in the TitansAtmosphereAbove about 400-450 km in Titans atmosphere the assumption oflocal thermodynamic equilibrium (LTE) breaks down for molecularvibrational levels of methane and various trace gases Above thisaltitude non-LTE significantly impacts the formation of infraredro-vibrational band emissions of these species observed in the limbviewing geometry We present detailed model of the non-LTE inmethane in the Titans atmosphere based on a new extendeddatabase of the CH4 spectroscopic parameters calculated for thisstudy We analyze vibrational temperatures of various 12CH4 and13CH4 levels as well as CH4 limb emissions in the 76 and 33 umspectral regions The impact on these emissions of many weakone-quantum and combinational bands which are missing incurrent databases is studied Implications for the non-LTEdiagnostics of the Cassini CIRS and VIMS measurements arediscussed

Author(s) Alexander Kutepov Ladislav Rezac ArtemFeofilov Michael Rey Andrei Nikitin Vladimir TyuterevInstitution(s) 1 Centre National de la RechercheScientifiqueEacutecole Polytechnique 2 Groupe de SpectromeacutetrieMoleacuteculaire et Atmospheacuterique UMR CNRS 3 Laboratory ofTheoretical Spectroscopy Institute of Atmospheric Optics 4 MaxPlanck Institute for Solar System Study 5 The Catholic Universityof America

31012 ndash Transmission windows in Titans lowertroposphere Implications for IR spectrometersaboard future aerial and surface missionsTitans thick atmosphere contains a 15 - 57 methane molefraction Methanes possession of fundamental overtone andcombination bands across much of the near and mid IR results insignificant absorption in the atmosphere across this spectralregion The consequence is spectral windowing such that Titanssurface can only be observed at a handful of methane transmissionwindows The narrow width of these windows for observationsfrom the top of the atmosphere (ToA) make only multispectralimaging of the surface possible This limits the information thatcan be gleaned about the surface composition which remainslargely unknown From ToA there is effectively zero transmissionat most wavelengths between the windows so that improvementsto the detectors or telescopes of IR spectrometers aboard orbital orflyby missions would not result in any appreciable widening of thewindows Only decreasing the methane column through whichobservations are made with a future mission operating near or onthe surface would result in any widening of the windows Wepresent a new line-by-line radiative transfer model to quantify thewindow widths for an IR spectrometer aboard an aerial or surfacemission to Titan We take spectral line parameters from theHITRAN database (Rothmann et al 2013) for methane and sixtrace gases include N2-N2 and N2-H2 collision-inducedabsorptions as measured by McKellar 1989 and the haze extinctionmeasured in situ by Huygens DISR The number of vertical layersin the model is chosen to correspond with the high cadence ofmeasurements of the physical conditions of Titans atmosphere byHuygens HASI We find that the transmission windows do notwiden appreciably for an aerial mission operating at altitudes onthe order of kilometers above the surface For surface missionsobserving at distances of order 10 m the windows widenconsiderably to encompass regions where absorptions fromhydrated minerals sulfates and pentane and higher order alkanescould be detected with hyperspectral observations We thus suggestthat infrared remote sensing from surface rather than aerialplatforms would be considerably better suited for characterizingTitans surface composition

Author(s) George D McDonald Paul M Corlies James JWray Jason D Hofgartner Sarah M Houmlrst Alexander GHayes Lucas R Liuzzo Jacob J BuffoInstitution(s) 1 Cornell University 2 Georgia Institute ofTechnology 3 Johns Hopkins University

31013 ndash Lifting Entry amp Atmospheric Flight (LEAF)System Concept Applications at Solar System BodiesWith an AtmosphereNorthrop Grumman and LrsquoGarde have continued the developmentof a hypersonic entry semi-buoyant maneuverable platformcapable of performing long-duration (months to a year) in situ andremote measurements at any solar system body that possesses anatmosphereThe Lifting Entry amp Atmospheric Flight (LEAF) family of vehiclesachieves this capability by using a semi-buoyant ultra-low ballisticcoefficient vehicle whose lifting entry allows it to enter theatmosphere without an aeroshell The mass savings realized byeliminating the heavy aeroshell allows significantly more payloadto be accommodated by the platform for additional sciencecollection and returnIn this presentation we discuss the application of the LEAF systemat various solar system bodies Venus Titan Mars and Earth Wepresent the key differences in platform design as well asoperational differences required by the various target

4-1

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94

environments The Venus implementation includes propulsivecapability to reach higher altitudes during the day and achieves fullbuoyancy in the mid-cloud layer of Venusrsquo atmosphere at nightTitan also offers an attractive operating environment allowingLEAF designs that can target low or medium altitude operationsalso with propulsive capabilities to roam within each altituderegime The Mars version is a glider that descends graduallyallowing targeted delivery of payloads to the surface or highresolution surface imaging Finally an Earth version could remainin orbit in a stowed state until activated allowing rapid responsetype deployments to any region of the globe

Author(s) Greg Lee Ronald Polidan Floyd Ross DanielSokol Steve WarwickInstitution(s) 1 Northrop Grumman

31014 ndash Titan Science with the James Webb SpaceTelescopeThe James Webb Space Telescope (JWST) scheduled for launch in2018 is an ambitious next-generation large-aperture (65 m) spaceobservatory focused on pushing the boundaries of infraredastronomy (06-280 μm) This long-wavelength focus gives it verysubstantial potential for solar system science since the thermalemissions from the surfaces and atmospheres of many planetsmoons and small bodies peak in this part of the spectrum Here wereport the findings of a task team convened to examine thepotential for Titan science using JWST These can be divided intofive broad areas (i) the surface especially the rotational lightcurve(ii) clouds in the lower atmosphere from direct imaging andnear-IR spectroscopy (iii) composition of the lower atmosphereespecially methane relative humidity (iv) composition of themiddle atmosphere including thermal and fluorescent emissionsfrom gases (v) hazes in the middle atmosphere including seasonalchanges in hemispheric contrast The capability of the major JWSTinstruments in each area is considered and limitations such aspotential saturation is noted and mitigation strategies (such assub-arraying) discussed Overall we find that JWST can makesignificant contributions to Titan science in many areas not least intemporal monitoring of seasonal change after the end of theCassini mission in 2017 in partnership with other next-generationobserving facilities (TMT GMT EELT ALMA)

Author(s) Conor A Nixon Richard Achterberg MateAdamkovics Bruno Bezard Gordon Bjoraker ThomasCornet Alexander Hayes Emmanuel Lellouch MarkLemmon Manuel Lopez Puertas Sebastien Rodriguez Christophe Sotin Nicholas Teanby Elizabeth Turtle RobertWestInstitution(s) 1 Cornell University 2 ESA ESAC 3 Instituto deAstrofisica de Andalucia 4 JHU APL 5 JPLCaltech 6 NASAGSFC 7 Observatoire de Paris 8 Texas AampM University 9Universite Paris-Diderot 10 University of Bristol 11 University ofCalifornia 12 University of Maryland

31015 ndash Vertical Profiles and Isotopic Ratios in HCNand its Isotopologues from ALMA Observations ofTitanThe photodissociation of methane (CH ) and molecular nitrogen(N ) provides the raw materials to create a suite of nitriles inTitans atmosphere the simplest and most abundant of these ishydrogen cyanide (HCN) The unprecedented sensitivity andspectral resolution of the Atacama Large MillimeterSub-millimeter Array (ALMA) permits the characterization of rotationaltransitions in this molecule and many of its isotopologues In thisstudy we leverage publicly available ALMA calibration observationsof Titan taken between April and July 2014 each lasting around160 seconds We report the detection of a new HCN isotopologueon Titan H C N and use this along with high signal-to-noiseobservations of HCN H CN HC N and DCN to determine theisotopic ratios C C N N and DH Isotopic ratios areknown to diverge throughout the solar system in planetaryatmospheres due to a variety of processes includingmass-dependent escape photochemistry and condensationTherefore accurate knowledge of isotopic ratios can provide

important constraints on models of the origin and evolution ofplanetary atmospheres

Author(s) Edward M Molter Conor A Nixon Martin ACordiner Steven B Charnley Patrick G J Irwin JosephSerigano Nicholas A TeanbyInstitution(s) 1 NASA Goddard Space Flight Center 2 OxfordUniversity 3 University of Bristol

31016 ndash Spectral Maps of Titanrsquos SurfaceTitanrsquos surface can be observed most clearly at 7 spectral regionsthat lie in between the strong methane bands in Titanrsquos spectrumWithin these rdquowindowsrdquo between 08 to 5 microns the surface isnonetheless obscured by methane and haze the latter of which isoptically thick at lower wavelengths Studies of Titanrsquos surface musteliminate the effects of atmospheric extinction which particularlyat high latitudes are not well constrained A more generalchallenge in the study of planetary surfaces is the extraction ofsubtle spectral features from a large quantity of low-resolutiondata which have dominant spectral trends upon which lessertrends reside This characteristic (a dominant spectral trend) isseen in Titanrsquos data images at all 7 wavelengths appear essentiallythe same with the bright terrain relatively bright at all wavelengthsand vise versa The question arises as to how to discern and mapthe smaller and orthogonal spectral trends of Titanrsquos surface inorder to investigate the composition Towards this goal we haveconstructed spectral maps of Titanrsquos surface by minimizing thecovariance matrix of the IF values (and separately the surfacealbedo) at the 7 window wavelengths This application of thePrincipal Components Analyses (PCA) yields the orthogonalspectral trends based on the variance of the IF values andseparately the surface albedos derived from radiative transfermodels Here we will present some of the interesting spectraltrends detected through the application of this method to smallsections of Titanrsquos surface

Author(s) Caitlin Ann Griffith Paulo Penteado Jake DTurner Tymon Khamsi Nicholas J MontielInstitution(s) 1 University of Arizona 2 University of Virginia

31017 ndash Titans Length-of-Day VariationsThe Cassini radar observation of Titan over several years show thatthe rotation period is slightly faster than the synchronous motion(Lorenz et al 2008 Stiles et al 2008 and 2011 Meriggiola 2012)The seasonal variation in the mean and zonal wind speed anddirection in Titanrsquos lower troposphere causes the exchange of asubstantial amount of angular momentum between the surfaceand the atmosphere (Tokano and Neubauer 2005 Richard et al2014) The rotation variation is affected by the influence of theatmosphere when we assume that Titan is a differentiated body andthe atmosphere interacts only with the outer layerIn this work we calculate variations of Titanrsquos length-of-day whenthe body is formed by two independent rotating parts and assumingthat friction occurs at the interface of them The tides areconsidered using the extension of two different theories -- theDarwin tide theory and Ferraz-Mellorsquos creep tide theory -- to thecase of one body formed by two homogeneous parts The resultsare compared and their differences are discussed

Author(s) Hugo Alberto Folonier Sylvio Ferraz-MelloInstitution(s) 1 IAG-USP

31018 ndash FT-IR measurements of mid-IR propene(C H ) cross sections and far-IR ammonia (NH ) lineintensitiesWe present spectroscopy measurements of propene (C H ) in themid-infrared and ammonia (NH ) in the far-infrared from twodifferent laboratory studies [1] For propene (CH -CH-CH aliaspropylene) which was detected in the stratosphere of Titan [Nixonet al 2013] temperature dependent cross sections in the 650 ndash1530 cm (65 ndash 153 μm) have been measured from a series ofhigh-resolution (00022 cm ) spectra of pure and N -mixturesamples of C H recorded at 150 ndash 296 K at Jet PropulsionLaboratory The observed spectral features cover the strongest v

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42

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band with its outstanding Q-branch peak at 912 cm and threeother strong bands of v v and v at 990 1442 and 1459 cm respectively In addition we have generated a HITRAN-formatempirical lsquopseudoline list containing line positions intensities andeffective lower state energies by fitting all the observed spectrasimultaneously The results are compared with early work fromrelatively warm temperatures (278 ndash 323 K) [2] For ammonia(NH ) we obtained multiple sets of high-resolution spectra in theTHz and far-infrared region (50 ndash 650 cm ) at room temperatureusing AILES beamline at Synchrotron SOLEIL France (NH ) Inthis work we have measured line intensities for more than 4500transitions and made quantum assignments for ~2900 linesincluding ~960 very weak ΔK = 3 forbidden lines Final results willbe compared with the current databases (eg HITRAN GEISA)and ab initio calculations [Research described in this paper wasperformed at the Jet Propulsion Laboratory California Institute ofTechnology under contract with the National Aeronautics andSpace Administration Sung and Yu acknowledge the SynchrotronSoleil for the AILES beam line time]

Author(s) Keeyoon Sung Geoffrey C Toon Timothy JCrawford Shanshan Yu John C Pearson Fridolin KwabiaTchana Laurent Manceron Olivier PiraliInstitution(s) 1 CNRS-Univ Paris Est 2 Jet PropulsionLaboratory

311 ndash Jovian Planets Atmospheres andInteriors31101 ndash Uranus Persistent Patterns and Featuresfrom High-SNR Imaging in 2012-2014Since 2012 Uranus has been the subject of an observing campaignutilizing high signal-to-noise imaging techniques at KeckObservatory (Fry et al 2012 Astron J 143 150-161) High qualityobserving conditions on four observing runs of consecutive nightsallowed longitudinally-complete coverage of the atmosphere over aperiod of two years (Sromovsky et al 2015 Icarus 258 192-223)Global mosaic maps made from images acquired on successivenights in August 2012 November 2012 August 2013 and August2014 show persistent patterns and six easily distinguishedlong-lived cloud features which we were able to track for longperiods that ranged from 5 months to over two years Two atsimilar latitudes are associated with dark spots and move with theatmospheric zonal flow close to the location of their associated darkspot instead of following the flow at the latitude of the brightfeatures These features retained their morphologies and drift ratesin spite of several close interactions A second pair of features atsimilar latitudes also survived several close approaches Several ofthe long-lived features also exhibited equatorward drifts andlatitudinal oscillations Also persistent are a remarkablenear-equatorial wave feature and global zonal band structure Wewill present imagery maps and analyses of these phenomenaPMF and LAS acknowledge support from NASA PlanetaryAstronomy Program PMF and LAS acknowledge funding andtechnical support from W M Keck Observatory We thank those ofHawaiian ancestry on whose sacred mountain we are privileged tobe guests Without their generous hospitality none of ourgroundbased observations would have been possible

Author(s) Patrick M Fry Lawrence A Sromovsky Imke dePater Heidi B Hammel Phillip MarcusInstitution(s) 1 AURA 2 Univ of Wisconsin 3 University ofCalifornia

31102 ndash Uranusrsquo Hemispheric Asymmetries in PolarCloud and Circulation StructuresWe report on the north polar region of Uranus in thepost-equinoctial era Near-IR imaging with Keck 2 using NIRC2 in2012-2014 revealed numerous small bright features as well assmall dark features between 50 degrees N and the north poleTracking of these features yielded circulation patterns with theremarkable result that the region from 60 degrees to at least 83degrees rotates about the northern pole as a solid body with a drift

rate of 41 degreeshour westward relative to the interior(Sromovsky et al 2015 Icarus 258 192-223) For the south polethe same latitude region had dramatically different characteristicsas judged by 1986 Voyager and 2003 Keck observations Thesouthern region showed no discrete near-IR features detailedcirculation measurements in that region were based solely onlow-contrast features in re-analyzed Voyager images (Karkoschka2015 Icarus 250 294-307) They revealed a large gradient in driftrates with values reaching twice that seen in the correspondingnorthern regionThe north-south asymmetry in circulation and cloudstructuremorphology is surprising because the distribution ofupper tropospheric methane is relatively symmetric roughlyconstant over a region from 30 S to 30 N and then declining athigher latitudes in both hemispheres The methane distributionsuggests symmetric down-welling motion in both polar regionswhich would inhibit formation of condensation clouds there incontrast to the observed dichotomy Some asymmetry may be aneffect of seasonal forcing since the north versus south polarmeasurements were made during different seasons If so thenmajor changes can be expected in the north polar region as Uranusproceeds toward its 2030 northern summer solstice Hubble STISobservations expected in October of 2015 will further examine thevertical distribution and stability of the polar methane abundancesFuture high-resolution imaging with Earth-based facilities will beable to track circulation changes (unless the developing north polarhaze obscures trackable clouds)This research was supported by grants from NASAs PlanetaryAstronomy program and from the Space Telescope ScienceInstitute

Author(s) Heidi B Hammel Lawrence Sromovsky PatFry Imke de PaterInstitution(s) 1 AURA 2 U Wisconsin 3 UC Berkeley

31103 ndash Meridional trends in Neptunersquos backgroundaerosol structureWe will present retrieval results for Neptunersquos aerosol structure inregions free of discrete cloud features using data from the KeckOSIRIS integral field spectrograph and a two layer model for theaerosols We use a Markov chain Monte Carlo algorithm toperform a thorough search of the parameter space this analysisreveals a substantial decrease in the optical depth of the upperaerosol layer with increasing distance from the equator similar towhat is observed for the ldquoupper hazerdquo of Uranus in a simpletwo-cloud model (eg de Kleer et al 2015) We also tentativelyidentify an increase in the optical depth of the deeper aerosol layerfrom the equator to the south pole opposite to what is observed forUranus but in agreement with the conclusions of Karkoschka ampTomasko (2011) for Neptune from HST-STIS spectroscopy Finallywe will present our constraints on Neptunersquos methane profile andits latitude dependence and discuss the significance of theseresults in terms of Neptunersquos global circulation

Author(s) Statia H Luszcz-Cook Katherine de Kleer Imkede Pater Mate Adamkovics Heidi B HammelInstitution(s) 1 American Museum of Natural History 2AURA 3 University of California Berkeley

31104 ndash Composition of the Upper Atmosphere ofNeptuneIt has been previously asserted that sulfur-bearing species such asCS and SO2 may be present in the upper atmosphere of Neptuneas remnants of cometary impacts (Iino et al 2014) Based on theexample of the SL9 event on Jupiter CS in particular may be one ofthe most abundant tracers of past cometary impactsWe present the results of our search for spectral (sub)mmsignatures of HCN CS and SO in Neptunersquos stratosphereperformed on archival public data from the Atacama LargeMillimetersubmillimeter Array (ALMA) Neither CS or SO2 were detected on Neptune We estimated anupper limit on the SO stratospheric ratio significantly lower thanthe SO ratio in comets suggesting that S and O cannot both solelyoriginate from a cometary impact

-1

18 16 7 -1

3-1

3

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1 1 1

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1 22 3

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2

96

Author(s) Elizabeth NanceInstitution(s) 1 St Marys College of Maryland

31105 ndash Exploring the connections between dark spotdynamics and zonal wind structure on UranusThe past several years have witnessed new observations revealingmore clouds and long-lived features in the atmosphere of UranusEach new set of images provides new cloud-tracking data and theopportunity to assess the structure of the zonal winds on UranusThis has led to a sequence of fits for the Uranian zonal winds withthe latest entries being those proposed in Sromovsky et al (2015)Karkoschka (2015) also provides a new view of the zonal winds butin this case through reanalyzing the Voyager II observations Whileall these profiles have in common features like a retrogradeequatorial jet the details of these profiles differ significantly Thesedifferences can be further accentuated when considering thevorticity profiles derived from these zonal winds As shown inLeBeau and Dowling (1998) and Hammel et al (2009)atmospheric simulations using different zonal vorticity profilessuggest that the vorticity gradient can affect the dynamics of darkspot vortices in the atmosphere Later work (Deng et al 2009) hasindicated that these dynamics may be further complicated by thepresence of cloud companion featuresTo further investigate these interactions some of the most recentzonal profiles are used in simulations of Uranus with the ExplicitPlanetary Isentropic Coordinate (EPIC) atmospheric model Byinducing vortices at different latitudes the effects of different zonalwind profiles on these features can be investigated A methanemicrophysics model is used to generate representative companionclouds The subsequent vortex and companion cloud motions canthen be compared to observations providing another tool in theeffort to understand possible changes in the zonal wind structure ofUranusReferencesLA Sromovsky et al Icarus 258192-223 2015E Karkoschka Icarus 250294-307 2015HB Hammel et al Icarus 201257-271 2009RP LeBeau and TE Dowling Icarus 132239-265 1998X Deng et al 1st AIAA Atmospheric and Space EnvironmentsConference AIAA-2009-3643 2009

Author(s) Raymond P Le Beau Csaba PalotaiInstitution(s) 1 Florida Institute of Technology 2 Saint LouisUniversity

31106 ndash Convection in Uranus and NeptuneIt is a common assumption of interior models that the outerplanets of our solar system are convective and that the internaltemperature distributions are therefore adiabatic If thisassumption is not correct the inferred internal structures of theseplanets can be different than typically thought Thereforeexploring this topic is crucial for planetary characterization Weinvestigate how the internal temperature profiles of Uranus andNeptune depend on the treatment of layered-convection We thenuse a set of possible temperature profiles associated with layered-convection together with density profiles derived from interiormodels that match the measured gravitational fields to derive thecompositions of the planets We find that the inferredcompositions of both Uranus and Neptune are not very sensitive tothe thermal profile In addition we show that calculating thethermal flux is important for understanding the energy transportmechanism in giant planets Finally we suggest that Neptunersquosinterior is just at the boundary between being convective orconductive and both configurations are consistent with its thermalflux while Uranusrsquo interior is mostly conductive This result isconsistent with recent dynamo models and useful forunderstanding the origin of the magnetic fields of the planets

Author(s) Morris Podolak Ravit Helled Gerald SchubertInstitution(s) 1 Tel Aviv University 2 UCLA

31107 ndash Revisiting the Galileo Probe results by astretched atmospheric modeThe Juno spacecraft will arrive at Jupiter in the late 2016 One of its

major scientific target is to measure the deep water abundancethrough its Microwave Radiometer (MWR) Prior to the arrival ofJuno the only observation of the weather layer of Jupiter was theGalileo probe (Niemann et al 1996 Wong et al 2004) whichreturned puzzling results In contrast to the detected 2 ndash 5 timesenrichment of CH NH and H S with respect to the solar valuesthe amount of water was severely subsolar Three dimensionalmodeling (Showman amp Dowling 2000) shows that dynamic drydowndrafts could create a huge trough in the material surface suchthat air flowing through the hot spots undergoes a temporaryincrease in pressure by a factor of 2 though it is still too small toexplain the Galileo probe results Inspired by the 3D modelingresult we constructed a stretched atmospheric model toparameterize the alteration of the thermodynamic state of air parcelby dynamics In our model an air parcel is initially in itsequilibrium condensation state and later has been dynamicallystretched to higher pressure modeled by a multiplicative factor SWhen S=1 the atmosphere is unaltered by dynamics representingthe equilibrium condensation model We found that when S=4the mixing ratios of H O NH and H S match all observationscoming from the Galileo probe site Thus this stretch parameterprovides a continuous representation of dynamic processes fromthe equilibrium condensation model to the Galileo probe resultsWe also show that the strength of stretch (S) can be retrieved fromJunoMWR limb darkening observations

Author(s) Cheng Li Andrew P Ingersoll Michael A JanssenInstitution(s) 1 Caltech 2 Jet Propulsion Laboratory

31108 ndash Updated Measurements of Saturnrsquos ZonalWind between 2004 - 2014 from Cassini ISS ImagesWe present updated zonal wind measurements of Saturn usingCassini ISS images taken between 2004 and 2014 We previouslyreported that there may be small seasonal changes in Saturnrsquoszonal wind profile but measurement uncertainties prevented usfrom making definite statements In our previous report we usedthe zonal standard deviation of the wind vectors as a proxy for themeasurement uncertainty However zonal standard deviationcontains contributions from both real spatial variations in the windspeed as well as uncertainties in the measurements This raised adifficulty in distinguishing small real changes in the wind fieldfrom the uncertainties in the measurement We have developed atechnique which isolates real spatial variations from measurementuncertainties by analyzing the correlation fields produced in thetwo-dimensional Correlation Imaging Velocimetry (CIV) cloud-tracking wind measurement method The CIV algorithm computesa wind vector by calculating the two-dimensional correlationbetween the pair of maps a peak in the correlation is judged to be amatch We determine the size shape and orientation of the peakby fitting an ellipse to the peak and calculating the areaeccentricity and orientation angle of the ellipse Combining thesemetrics provides a measure of the uncertainty associated withindividual wind vectors Vectors with smaller sharper morecircular peaks will have a smaller uncertainty than vectors withlarger flatter more elliptical peaks Using this new technique ournew measurements reveal small temporal changes in the zonalwind profiles Our work has been supported by NASA PATMNNX14AK07G and NSF AAG 1212216

Author(s) John J Blalock Kunio M Sayanagi Andrew PIngersoll Shawn P Ewald Ulyana A DyudinaInstitution(s) 1 California Institute of Technology 2 HamptonUniversity

31109 ndash On the Ammonia Absorption on SaturnThe ammonia absorption bands centered at wavelengths of 645and 787 nm in the visible spectrum of Saturn are very weak andoverlapped with more strong absorption bands of methaneTherefore the allocation of these bands is extremely difficult Infact the NH3 band 787 nm is completely masked by methane TheNH3 645 nm absorption band is superimposed on a relatively weakshortwave wing of CH4 band in which the absorption maximumlies at the wavelength of 667 nm In 2009 during the equinox onSaturn we have obtained the series of zonal spectrograms by

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scanning of the planet disk from the southern to the northern polarlimb Besides studies of latitudinal variation of the methaneabsorption bands we have done an attempt to trace the behavior ofthe absorption of ammonia in the band 645 nm Simple selection ofthe pure NH3 profile of the band was not very reliable Thereforeafter normalizing to the ring spectrum and to the level of thecontinuous spectrum for entire band ranging from 630 to 680 nmin the equivalent widths were calculated for shortwave part of thisband (630-652 nm) where the ammonia absorption is present anda portion of the band CH4 652-680 nm In any method ofeliminating the weak part of the methane uptake in the short wingshow an increased ammonia absorption in the northernhemisphere compared to the south This same feature is observedalso in the behavior of weak absorption bands of methane incontrast to the more powerful such as CH4 725 and 787 nm Thisis due to the conditions of absorption bands formation in theclouds at multiple scattering Weak absorption bands of methaneand ammonia are formed on the large effective optical depths andtheir behavior reflects the differences in the degree of uniformity ofthe aerosol component of the atmosphere of Saturn

Author(s) Victor G Tejfel A M Karimov P G Lyssenko GA KharitonovaInstitution(s) 1 Fessenkov Astrophysical Institute

31110 ndash Saturnrsquos fast spin determined from itsgravitational field and oblatenessKnowledge of the rotation period of a giant planet is crucial forconstraining its internal structure and atmosphere dynamicsHowever this physical property is not accurately determined in thecase of Saturn Spacecraft measurements of Saturnrsquos radioemission have revealed an uncertainty of nearly 10 minutes in itsrotation period Theoretical efforts to infer the rotation period haveincreased the uncertainty even more and at present Saturnrsquosrotation period is thought to be between sim 10h 32m and sim10h 47mWe present a new statistical optimization approach to determineSaturnrsquos rotation period We find that by using its measuredgravitational field and without imposing any constraints on theplanetary shape and internal density profile Saturnrsquos rotationperiod can be determined to within several minutes Moreover ifwe include limits based on the observed planetary shape andpossible density profiles the rotation period can be determined tobe 10h 32m 44s plusmn 46s The success of our method is confirmed byapplying it for Jupiter and reproducing exactly its measuredrotation period which is well-known

Author(s) Ravit Helled Eli Galanti Yohai KaspiInstitution(s) 1 Tel-Aviv University 2 The Weizmann Instituteof Science

31111 ndash Waves and eddies simulated byhigh-resolution Global Climate Modeling of Saturnstroposphere and stratosphereThe longevity of the Cassini mission permitted a detailed analysisof Saturns tropospheric storms an exceptional coverage ofSaturns Great White Spot (and subsequent stratosphericwarming) an assessment of the remarkable stability of thehexagonal polar jet and the seasonal monitoring of Saturnsequatorial oscillation Those observations open new questions thatadd to those related to the extent and forcing of Saturns alternatedjets One of the best step forward to progress is to build a GlobalClimate Model (GCM) for giant planets by coupling anhydrodynamical solver (dynamical core) with physical models forexternal forcings on the fluid We built a new GCM for Saturn bothversatile and powerful enough to resolve resolve the eddies arisingfrom hydrodynamical instabilities and forcing the planetary-scalejets extend from the troposphere to the stratosphere with goodenough vertical resolution and use optimized radiative transfer topredict seasonal tendencies over decade-long giant planets yearsTo that end we coupled our seasonal radiative model tailored forSaturn with DYNAMICO the next state-of-the-art dynamical corefor Earth and planetary climate studies in our lab using an originalicosahedral mapping of the planetary sphere which ensuresexcellent conservation and scalability properties in massively

parallel resources Using a new petaflops acquisition by CINES(France) we run our GCM for Saturn down to unprecedentedresolutions of 14deg and 18deg and to run sensitivity tests at 12degresolution Those high-resolution GCM runs show a detailed viewinto a striking variety of eddies and vortices on Saturn as well asthe arising of alternated banded jets the formation of a polarvortex the deformation of the polar jet into polygonal structuresWe will assess the nature and characteristics of both eddies andeddy-driven features in the troposphere and in the stratosphereusing spectral and dynamical analysis We will discuss how closeour simulations are to the observed features by Cassini and otherobservational campaigns and assess which processes are in need tobe improved in our GCM Perspectives for Jupiters atmosphericmodeling will also be described

Author(s) Aymeric Spiga Sandrine Guerlet YannMeurdesoif Mikel Indurain Ehouarn Millour ThomasDubos Meacutelody Sylvestre Jeacutereacutemy Leconte Thierry FouchetInstitution(s) 1 Laboratoire dAstrophysique de BordeauxCentre National de la Recherche Scientifique 2 LaboratoiredEtudes Spatiales et dInstrumentation en AstrophysiqueUniversiteacute Pierre et Marie Curie 3 Laboratoire de MeacuteteacuteorologieDynamique Centre National de la Recherche Scientifique 4Laboratoire de Meacuteteacuteorologie Dynamique Ecole Polytechnique 5Laboratoire de Meacuteteacuteorologie Dynamique Universiteacute Pierre etMarie Curie 6 Laboratoire des Sciences du Climat et delEnvironnement Commissariat agrave lEnergie Atomique

31112 ndash Polar Disturbance Surrounding a Long LivingCyclone in Saturnrsquos AtmosphereIn 2014 and 2015 a large lsquodark spotrsquo about 6000 km in length andlocated at planetocentric latitude +585deg (+63deg N planetographic)was tracked on the best ground-based amateur images of Saturnrevealing a long-lived feature an uncommon phenomenon inSaturnrsquos atmosphere Images captured by the Imaging ScienceSubsystem (ISS) onboard Cassini spacecraft showed the feature asa very contrasted dark spot in the MT3 filter and barely visible inthe deep sounding filters CB2 and CB3 On mid-May 2015ground-based observations obtained by amateur astronomersoperating small telescopes started to show a disturbance aroundthis dark spot Following the onset of this disturbance the drift ofthe dark spot remained unaltered and equal to the motion it hadpreviously but thedisturbance evolved zonally in a complex manner giving hints of akind of large scale phenomena in Saturnrsquos atmosphere of anunprecedented type Unfortunately the orbital path of the Cassinispacecraft was not appropriate to see details of the disturbance atthat time Images by the Hubble Space Telescope (HST) WFC3instrument obtained in directorrsquos time (DDT) allow us to describethe detailed dynamics of the disturbance while the study of itslong-term evolution is possible thanks to the efforts of thecommunity of amateur astronomers In this work we analyze thedynamics of the region before the start of the disturbance and thedynamics and evolution of the disturbance after its onset

Author(s) Teresa Del Rio Gaztelurrutia Agustiacuten Sanchez-Lavega Arrate Antuntildeano Ricardo Hueso Santiago Peacuterez-Hoyos Jose F Rojas Mike H Wong Amy A Simon Imke dePater Josep M Goacutemez-ForrelladInstitution(s) 1 Fundacioacute Observatori Esteve Duran 2 NASAGoddard Space Flight Center 3 University of California 4University of the Basque Country (UPVEHU)

31113 ndash Jupiters auroral-related thermal infraredemission from IRTF-TEXESAuroral processes on Jupiter can be observed at a large range ofwavelengths Charged particles of the solar wind are deflected byJupiterrsquos magnetic field and penetrate the atmosphere at highlatitudes This results in ion andor electron precipitation whichproduces emission at X-ray UV visible near-infrared and evenradio wavelengths These observations indicate three distinctfeatures of the aurora 1) filament-like oval structures fixed at themagnetic poles (~80degW (System III) in the south ~180degW in thenorth) 2) spatially-continuous but transient aurora that fill these

1 1 11

1 2 2

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44 4 44 4 3 2

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98

oval regions and 3) discrete spots associated with the magneticfootprints of Io and other Galilean satellites Howeverobservations in the thermal infrared indicate the aurora alsomodify the neutral atmosphere Enhanced emission of CH isobserved coincident with the auroral ovals and indicatesheightened stratospheric temperatures possibly as a result of jouleheating by the influx of charged particles Stronger emission is alsoobserved of C H C H C H and even C H though previouswork has struggled to determine whether this is a temperature orcompositional effect In order to quantify the auroral effects on theneutral atmosphere and to support the 2016 Juno mission (whichhas no thermal infrared instrument) we have performed a retrievalanalysis of IRTF-TEXES (Texas Echelon Cross EchelleSpectrograph 5- to 25-μm) spectra obtained on Dec 11 2014 nearsolar maximum The instrument slit was scanned east-west acrosshigh latitudes in each hemisphere and Jupiterrsquos rotation was usedto obtain ~360deg longitudinal coverage Spectra of H S(1) CH C H C H and C H emission were measured at a resolvingpower of R = 85000 allowing a large vertical range in theatmosphere (100 ndash 0001 mbar) to be sounded Preliminaryretrievals of the vertical temperature profile from H S(1) and CHmeasurements at 60degN 180degW (on aurora) in comparison to60degN 60degW (quiescent) indicate the majority of auroral heatingoccurs from 10- to 1-μbar We plan on further testing thetemperature retrievals and adopting these results in thesubsequent retrievals of C H C H and C H to determinecompositional contrasts

Author(s) James Sinclair Glenn Orton ThomasGreathouse Leigh Fletcher Patrick IrwinInstitution(s) 1 Atmospheric Oceanic and Planetary PhysicsUniversity of Oxford 2 Jet Propulsion Laboratory 3 SouthwestResearch Institute 4 University of Leicester

31114 ndash Deriving Temperatures from the Homopauseof JupiterRecently Kim et al (Icarus 2015) derived homopausetemperatures from several places on the north and south polarregions of Jupiter by analyzing the 3-μm spectro-images of CH which were obtained using the Gemini Near-Infrared Spectrograph(GNIRS) The spectral resolution of the data was R~18000 whichis enough to resolve the sharp 3-μm emission lines of the P and Qbranches of CH From the next yearrsquos JUNO encounter withJupiter we are expecting low resolution spectra from JUNOrsquos IR2-5 μm spectrograph whose resolution is only R~300 at 3 μm Wewill present a method to derive homopause temperatures fromlow-resolution spectra utilizing the gross envelopes of the P Q Rbranch lines of CH We will discuss possible sciences extractedfrom the constructed maps of homopause temperatures over theauroral or non-auroral regions of Jupiter

Author(s) Sang J KimInstitution(s) 1 Kyunghee Univ

31115 ndash Photochemistry mixing and transport inJupiterrsquos stratosphere constrained by CassiniJupiterrsquos obliquity and eccentricity drive the seasonal forcing on itsatmosphere The seasonal variations on its stratospherictemperature through radiative heating and composition throughphotochemistry are smaller than for Saturn due to a lowerobliquity and eccentricity Although the physical conditions inthese two planets are different the stratospheric photochemistry isinitiated and controlled by the methane photolysis [1] We adapteda 2D (altitude-latitude) seasonal photochemical model of Saturn[2] to Jupiter We compare the seasonal effects on the atmosphericcomposition between these two planets We use previous 1Dphotochemical models for the vertical mixing efficiency [13] andrecent Cassini observations to constrain the meridional mixingefficiency and transport processes [456]Cassinirsquos flyby of Jupiter has allowed mapping its stratospherictemperature as a function of latitude [7] It has also revealed themeridional distribution of hydrocarbons [89] which weresuggested by earlier studies [104] Previous models suggest thatvertical mixing alone is not sufficient to reproduce the observations

of C H and C H [56] and that meridional mixing is needed Weshow that in addition to meridional mixing advective circulation isrequired to reproduce Cassini observations of C H Preliminaryresults from our model suggest an equator-to-pole circulation cellin Jupiterrsquos stratosphere around 30-001 mbarReferences[1] Moses et al 2005 JGR 110 8001[2] Hue et al 2015 Icarus 257 163-184[3] Gladstone et al 1996 Icarus 119 1-52[4] Kunde et al 2004 Science 305 1582-1587[5] Liang et al 2005 ApJ Lett 635 L177-L180[6] Lellouch et al 2006 Icarus 184 (2) 478-497[7] Simon-Miller et al 2006 Icarus 180 (1) 98-112[8] Nixon et al 2007 Icarus 188 47-71[9] Nixon et al 2010 PSS 58 1667-1680[10] Maguire et al 1984 Bulletin of the AAS 16 647-647

Author(s) Vincent Hue Franck Hersant Thibault Cavalieacute Michel DobrijevicInstitution(s) 1 LAB Universiteacute de Bordeaux CNRS UMR5804 2 LESIA Observatoire de Paris CNRS Universiteacute Paris 06Universiteacute Paris-Diderot

31116 ndash Saturns Stratospheric Water VaporDistributionWater is a sought after commodity in the solar system It is used asan indication of life planetary formation timescales and signaturesof past cometary impacts In Saturnrsquos atmosphere there are twosources of water an internal primordial reservoir that is confinedto the troposphere and an external source of unknown origin thatdelivers water to the stratosphere Potential sources ofstratospheric water include Saturnrsquos main rings (via neutral infallandor ions transported along magnetic field lines ndash ldquoRing Rainrdquo)interplanetary dust particles and the E-ring that is supplied withwater from the plumes of Enceladus Measuring the latitudinal andseasonal variation of H O on Saturn will constrain the source ofSaturnrsquos stratospheric waterCassinirsquos Composite InfraRed Spectrometer (CIRS) has detectedemission lines of H O on Saturn at wavelengths of 40 and 50microns CIRS also retrieves the temperature of the stratosphereusing CH lines at 77 microns Using our retrieved temperatureswe derive the mole fraction of H O at the 05-5 mbar level forcomparison with water-source models The latitudinal variation ofstratospheric water vapor will be presented as a first step inunderstanding the external source of water on Saturn Theobserved local maximum near Saturnrsquos equator supports either aneutral infall from the rings or a source in the E-ring We will lookfor secondary maxima at mid-latitudes to determine whether ldquoRingRainrdquo also contributes to the inventory of water in Saturnrsquos upperatmosphere

Author(s) Brigette E Hesman Gordon L Bjoraker RichardK Achterberg Paul N Romani Patrick GJ IrwinInstitution(s) 1 NASA GSFC 2 Oxford University 3 UnivMarylandNASA GSFC

31117 ndash Saturns stratospheric temperature andcomposition in 2015 from CassiniCIRS limbobservationsAs Cassinis solstice mission goes on our understanding ofSaturns atmospheric seasonal evolution continues to build upInfrared spectra acquired by CassiniCIRS in limb viewinggeometry in 2015 (end of spring in the northern hemisphere) areanalysed to retrieve vertical profiles of the stratospherictemperature and hydrocarbon abundances at several latitudesspanning tropical mid and high latitudesThese new measurements reveal how the equatorial oscillationcontinues to propagate downward with time and help bettercharacterize its period At 40N the previously observedtemperature anomaly and enrichment in hydrocarbons associatedwith the 2011 storm have since disappeared Compared to previousmeasurements acquired between 2005 and 2012 (Guerlet et alIcarus 2009 Sylvestre et al Icarus 2015) these new limbmeasurements also allow the study of the warming and cooling

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trends at different pressure levels associated with the change ofseasons These trends will be compared to predictions from aradiative climate model (Guerlet et al Icarus 2014)We also report the detection of benzene and aerosols at 77N whichconfirms that these compounds are enhanced in auroral regionscompared to low and mid latitudes as already derived from aprevious measurement at 80S in 2007 (Guerlet et al AampA 2015)The aerosol optical depth is found twice lower at 77N in 2015 (endof spring in N hemisphere) than that derived at 80S in 2007 (endof summer in S hemisphere) However whether this northsouthdifference stems from a permanent asymmetry or from a temporalvariation of the aerosol optical depth cannot be assessed from thesetwo measurements alone We will discuss implications for the roleof aerosols in the radiative forcing of the polar regions

Author(s) Sandrine Guerlet Thierry Fouchet BrigetteHesman Gordon Bjoraker Aymeric Spiga Melody SylvestreInstitution(s) 1 Laboratoire de Meteorologie Dynamique 2LESIA Observatoire de Paris 3 NASAGSFC

31118 ndash Effect of the 77 degree N Jet on SaturnrsquosHexagon Cloud MorphologyWe study how Saturnrsquos 77 degree N jet shapes the sharp edges ofthe hexagon The hexagonal morphology is shaped by ameandering jetstream that encircles the north pole of Saturn ataround 77 degree N planetographic latitude (Antunano et al 2015)Laboratory and numerical models have demonstrated that ajetstream could develop a six-sided shape in two different ways Inthe first which we call the vortex street model alternating pairs ofcyclonic and anticyclonic vortices form through shear instabilitiesand form a hexagonal pattern (Barbosa Aguiar et al 2010 Morales-Juberias et al 2011) In the second which we call the meanderingjet model a jetstream accompanied by a sharp gradient of potentialvorticity develops a meandering path without accompanyingvortices (Morales-Juberias et al 2015) The observed wind field ofSaturnrsquos hexagon is consistent with that of the meandering jetmodelIn the present study we first present Cassini ISS images of thehexagon captured using various filters and show that its cloudband boundary has a sharp contrast gradient along the path of thejetstream at 77 degree N We hypothesize that this sharp boundaryis a consequence of the transport barrier effect of the meanderingjetstream We further hypothesize that such sharp cloudboundaries cannot accompany a hexagonal jet formed through avortex street scenario We test our hypothesis by performingnumerical simulations using the EPIC atmosphere model (Dowlinget al 1998 2004) We use passive tracers to represent clouds in oursimulations to study the mixing across the jetstream in both thevortex street and meandering jet scenarios and test whether sharphexagonal cloud morphology could be reproduced by either of thescenariosOur research is supported by the NASA grants from Outer PlanetResearch (NNX12AR38G) Planetary Atmospheres(NNX14AK07G) Cassini Data Analysis (NNX15AD33G) programsand NSF Astronomy amp Astrophysics Program grant 1212216

Author(s) Kunio M Sayanagi Rauacutel Morales-Juberiacuteas John J Blalock Richard G Cosentino Andrew P Ingersoll Shawn P Ewald Ulyana A DyudinaInstitution(s) 1 California Institute of Technology 2 HamptonUniversity 3 New Mexico Institute of Mining and Technology

31119 ndash The Ongoing Evolution of a Long-LivedAnticyclone in Saturnrsquos Great Storm Region as seen byCassiniVIMSOnce the home of the enigmatic String of Pearls feature on Saturnthe region of 34 N was the scene of a titanic storm system thatswept around the planet in late 20102011 It left two things in itswake - a clear 5-μm bright zone around the planet and a curiousand persistent anticylone both of which remain to this day Wehave observed this anticyclone with CassiniVIMS since 2011 andfind that it seems to oscillate up and down latitudinally in thisstormy region Centered at 359 planetocentric latitude in May2011 it drifted northward to 378 in 2012 hovered near 37

through 2013 then settled southward back down to ~359 in2014 2015 has it once again drifting northward to ~37 It alsoperiodically interacts with the dark band above it exchangingmaterial in August 2013 and May 2015 We measured a progradezonal drift speed of ~22 ms in 2012 increasing as much as 60through 2013 then relaxing back to a more moderate ~15 ms in2014 as the oval sagged southward We expect its current 154 msrate to increase if it continues to drift northward in latitudefollowing the Voyager wind profile The feature has varied in size aswell spanning 49 x 32 in 2011 elongating zonally to 73 x 29by 2013 contracting in 2014 to an average of ~55 x ~29 andgrowing again to ~9 x ~4 in 2015 with an extended tendril ofmaterial streaming off one edge in May By August it wassymmetrically oval again It has varied in terms of cloudiness being~90 5-μm dark (obscured) in 2011 whereas by 2013 it wasmostly bright (clear) with a thin dark edge now returning to ~90dark in 2015 By utilizing night observations to isolate thermal fluxwe find that the mean 5-μm flux coming from the anticyclone hasdiminished steadily by about 50 since 2013 The storm latitude of~34 N itself has remained remarkably 5-μm bright since 2011 buthas begun to dim as well and is now bisected by a thin dark cloudyribbon which appears associated with the anticyclone We arecontinuing to monitor the evolution of the anticyclone and theStorm Region over time with CassiniVIMS

Author(s) Thomas W Momary Kevin H Baines SarahBadman Robert H Brown Bonnie J Buratti Roger N Clark Philip D Nicholson Christophe SotinInstitution(s) 1 Cornell University 2 Lancaster University 3NASAJet Propulsion Laboratory 4 Planetary Science Institute 5SSECUniversity of Wisconsin-Madison 6 University of Arizona

31120 ndash The search for atmospheric waves below theclouds of Jupiter using radio wavelength observationsWe observed Jupiter at 2 cm wavelength with the VLA in earlyFebruary 2015 This particular frequency is mostly sensitive tovariations in ammonia opacity and probes a depth between 1 and 2bars pressure below the visible cloud deck at 07 bars The dataacquired was projected into a cartographic map of the planetfollowing the technique of Sault et al (2004) The horizontalresolution is ~1500 km and we have examined the map foratmospheric waves on these and larger scales The map hasrevealed prominent features near 8N in the North Equatorial Beltwhere the 5 micron hotspot planetary wave feature also residesThe Great Red Spot is also prominent and has a noticeablemeridional asymmetry We will present our analysis of the spatialstructure for the entire map and best fit of its wave featurespectrumOur research is supported by NRAO and NMT

Author(s) Rick Cosentino Bryan Butler Bob Sault RaulMorales-Juberias Amy SimonInstitution(s) 1 New Mexico Institute of Mining andTechnology 2 NRAO 3 Solar System Exploration DivNASAGSFC

31121 ndash Numerical Modeling of Normal-ModeOscillations in Planetary Atmospheres Application toSaturn and TitanWe have developed a numerical model to calculate the frequenciesand eigenfunctions of adiabatic non-radial normal-modeoscillations in the gas giants and Titan The model solves thelinearized momentum energy and continuity equations for theperturbation displacement pressure and density fields and solvesPoissonrsquos equation for the perturbation gravitational potential Theresponse to effects associated with planetary rotation including theCoriolis force centrifugal force and deformation of the equilibriumstructure is calculated numerically This provides the capability toaccurately compute the influence of rotation on the modes even inthe limit where mode frequency approaches the rotation rate whenanalytical estimates based on functional perturbation analysisbecome inaccurate This aspect of the model makes it ideal forstudying the potential role of low-frequency modes for drivingspiral density waves in the C ring that possess relatively low pattern

1 23 3 1 2

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speeds (Hedman MM and PD Nicholson MNRAS 4441369-1388) In addition the model can be used to explore theeffect of internal differential rotation on the eigenfrequencies Wewill (1) present examples of applying the model to calculate theproperties of normal modes in Saturn and their relationship toobserved spiral density waves in the C ring and (2) discuss how themodel is used to examine the response of the superrotatingatmosphere of Titan to the gravitational tide exerted by SaturnThis research was supported by a grant from the NASA PlanetaryAtmosphere Program

Author(s) Andrew James Friedson Leon DingInstitution(s) 1 JPL 2 Summer Undergraduate ResearchFellow Caltech

31122 ndash Analysis of Cassini UVIS Extreme and FarUltraviolet Observations of Saturnrsquos AtmosphereThe atmosphere of Saturn is mainly composed of H and neutralatomic helium The study of He 584 Aring and H Lyman-αbrightnesses is interesting as the EUV and FUV (Extreme and FarUltraviolet) planetary airglow have the potential to yield usefulinformation about mixing and other important parameters in itsthermosphere Time variation asymmetries and polarenhancement of the airglow are also possible and analysis alreadyperformed using the public archived Cassini mission data sets haveshown we can solve some of the outstanding problems associatedwith these phenomena for SaturnSpecifically we have (1) examined epochal eddy mixing disparitiesin the Saturnian upper atmosphere and quantify temporal mixingvariations that may have occurred in the upper atmosphere ofSaturn as may be evidenced in Cassini mission data (2) quantifiedany enhanced mixing in the auroral regions of Saturn and (3)performed a robust study of Saturnian H Lyman-α brightness withthe view to discover any longitudinal H Lyman-α planetaryasymmetry or ldquobulgerdquo across the disc such as was discovered byVoyager at Jupiter indicative of the distribution of atomic H andaccounting for the observed flux and any variations from thenormal temperature profileWe have analyzed Cassini UVIS EUV and FUV airglow data fromSaturn using sophisticated photochemical and radiative transfermodels to investigate unexplained differences in the dynamicalprocesses operating within its upper atmosphere Powerful analysistechniques allow us to extract information on atmospheric mixingtemperatures and temporal changes due to the solar and seasonalcycles from the variations in distribution and intensity of airglowemissions that result We report on results of these efforts to date

Author(s) Christopher D Parkinson Tommi Koskinen Guillaume Gronoff Yuk L Yung Larry EspositoInstitution(s) 1 California Institute of Technology 2 LASPUniversity of Colorado 3 LPL 4 SCIENCE SYSTEMS ANDAPPLICATIONS INC 5 Univ of Michigan

31123 ndash Peeking into Saturns atmosphere the HSTlow-phase angle viewRecent Hubble Space Telescope WFC3 observations of Saturn haveprovided a low-phase angle view of the planet that nicelycomplements the higher phase angles and increased spatialresolution view from the Cassini spacecraft HST orbits wereperfectly timed for observing an atmospheric perturbation at polarlatitudes but they serendipitously captured other interestingfeatures at the Equatorial Zone (EZ) In this presentation we willdiscuss how the synergy between the CassiniISS and HSTWFC3observations provides an excellent way for peeking into Saturnsatmosphere and analyze the vertical distribution and properties ofthe particles and aerosols located in the lower stratosphere andupper troposphere of the planet We first discuss how CassiniISSobservations at a variety of phase angles constrain particleproperties and phase function in particular at the Equatorial ZoneThis had not been investigated since the early 1980s (Tomasko ampDoose 1984) more than a Saturnian year before the current workWe will also discuss the sizes and shapes of particles in thetroposphere as constrained by the retrieved phase function Withthis information the HSTWFC3 observations at 10 filters from

near-ultraviolet to the near-infrared provide substantialinformation on the vertical cloud structure and composition thefilters in and out of the intermediate and deep methane bands atthe near infrared give information on particle number densityaround the tropopause level (5-10 partcm ) and down to theammonia condensation level while near-ultraviolet and blue filterscharacterize the absorption of unknown chromophores in Saturnsatmosphere We will further show observations and radiativetransfer models of selected atmospheric features that haveimportant dynamical implications for understanding Saturnsatmospheric dynamics at the EZ and the Northern polaratmosphere In particular fast-moving features in the EZ withVoyager-era speeds seem to be located deeper (ge 2 bar) than thefeatures used for cloud-tracking since the pre-Cassini era (01 -1bar) thus simultaneously sounding for the first time threeseparate levels in the Equatorial region of the planet withsubstantially different wind speeds

Author(s) Santiago Perez-Hoyos JF Sanz-Requena ASanchez-Lavega R Hueso T del Riacuteo-Gaztelurrutia JFRojas AA Simon MH Wong I de Pater PGJ Irwin IIrizarInstitution(s) 1 Goddard Space Flight Center 2 Universidaddel Pais Vasco UPVEHU 3 Universidad Miguel de Cervantes 4University of California 5 University of Oxford

31124 ndash The Colors of SaturnVery little is known about the coloring agents or chromophoresthat color the clouds of Saturnrsquos belts and zones Although theclouds of Saturn are more muted in their coloration and do notexhibit the more striking variations seen among Jupiterrsquos beltszones and cyclonic storm features the physical processes thatrender Saturnrsquos clouds a yellowish hue are likely similar to those atwork on Jupiter Thus a comprehensive color study that includesboth Jupiter and Saturn is warranted to advance our understandingof chromophores in the giant planet atmospheres Here we reporton our efforts to characterize the colors of Saturnrsquos cloudsThis study involves the analysis of two imaging data sets thosefrom Cassinirsquos Imaging Science Subsystem (ISS) and Wide FieldPlanetary Camera 2 images taken with the Hubble Space Telescope(HST) The HST data were acquired in 1994 1998 2002 and 2004using eleven different filters spanning 255-973 nm After theimages were photometrically and geometrically calibrated we usedthem to create low resolution spectra for six different latituderegions the Equatorial Zone the Equatorial Belt the SouthEquatorial Belt the South Temperate Zone the South TemperateBelt and the South South Temperate Belt The Cassini ISS imageswere acquired in 2004 and 2011 using twelve different filtersspanning 258-938 nm and corresponding low resolution spectra ofthe same latitude regions were generated using the ISS images Wecompare these low resolution spectra to Saturnrsquos full-disk spectrum(Karkoschka E 1994 Icarus 111 174) to examine colors of discretelatitudes versus the full-disk spectrum of Saturn The extensivetemporal coverage afforded by the combination of the HST and ISSimages will enable us to explore possible seasonal variations inSaturnrsquos cloud colors Finally we examine the color evolution ofthe major 2011 storm on Saturn using the ISS dataThis work was supported by the Discovery Scholars Program inNMSUrsquos College of Arts and Sciences and NASArsquos Outer PlanetsResearch program through grant NNX12AJ14G

Author(s) Kayla DeVogel Nancy Chanover AlexanderThelenInstitution(s) 1 New Mexico State University

31125 ndash Photochemistry in Saturnrsquos Ring-ShadowedAtmosphere Modulation of Hydrocarbons andAerosolsCassini has been orbiting Saturn for over eleven years now Duringthis epoch the ring shadow has moved from covering much of thenorthern hemisphere (the solar inclination was 24 degrees) tocovering a large swath south of the equator and it continues tomove southward At Saturn Orbit Insertion in 2004 the projectionof the A-ring onto Saturn reached as far as 40N along the central

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meridian (52N at the terminator) At its maximum extent the ringshadow can reach as far as 48NS (58NS at the terminator) Thenet effect is that the intensity of both ultraviolet and visiblesunlight penetrating through the rings to any particular latitudewill vary depending on both Saturnrsquos axis relative to the Sun andthe optical thickness of each ring system In essence the rings actlike semi-transparent venetian blindsOur previous work examined the variation of the solar flux as afunction of solar inclination ie for each 725-year season atSaturn Here we report on the impact of the oscillating ringshadow on the photolysis and production rates of hydrocarbons(acetylene ethane propane and benzene) and phosphine inSaturnrsquos stratosphere and upper troposphere The impact of theseproduction and loss rates on the abundance of long-livedphotochemical products leading to haze formation are exploredSimilarly we assess their impact on phosphine abundance adisequilibrium species whose presence in the upper tropospherecan be used as a tracer of convective processes in the deeperatmosphereWe will also present our ongoing analysis of Cassinirsquos datasets thatprovide an estimate of the evolving haze content of the northernhemisphere and we will begin to assess the implications fordynamical mixing In particular we will examine how the nowfamous hexagonal jet stream acts like a barrier to transportisolating Saturnrsquos north polar region from outside transport ofphotochemically-generated molecules and hazeThe research described in this paper was carried out in part at theJet Propulsion Laboratory California Institute of Technologyunder a contract with the National Aeronautics and SpaceAdministration Copyright 2015 California Institute of TechnologyGovernment sponsorship is acknowledged

Author(s) Scott G Edgington Sushil K Atreya Eric HWilson Kevin H Baines Robert A West Gordon L Bjoraker Leigh N Fletcher Tom MomaryInstitution(s) 1 Goddard Space Flight Center 2 Jet PropulsionLaboratoryCalTech 3 University of Michigan 4 University ofOxford

31126 ndash Comprehensive Optical Coverage of Jupiterfor Spectral Comparison with NH SHThe distinct regions in Jupiters atmosphere ndash comprised of beltszones storms and the Great Red Spot ndash are thought to be coloredby unidentified chemical compounds called chromophores Thesemolecules created through Jupiters complex atmosphericchemistry may be responsible for the spectral slope and lack offeatures in the blue (shortwards of 500 nm) portion of Jupitersoptical spectrum Though many candidate compounds have beenproposed ndash such as ammonium hydrosulfide (NH SH) ndash theidentity of the coloring agent (or agents) remains elusive due to thesparse history of laboratory experiments conducted at appropriatetemperatures and pressures for Jovian conditions To build onprevious ground-based observations of Jupiter in the optical wehave obtained spectra with the Dual Imaging Spectrograph ndashmounted on the Astrophysical Research Consortium 35-metertelescope at Apache Point Observatory ndash over a wide portion of thevisible spectrum (~380-880 nm) by utilizing multiple centralwavelength settings These observations taken during February2013 and April 2015 cover multiple latitudinal regions on Jupiterincluding the Great Red Spot In this study we present the spectralcomparison of various regions in the Jovian atmosphere with datataken at the Cosmic Ice Laboratory at NASArsquos Goddard Space FlightCenter By exposing thin films of NH SH to varying amounts ofionizing radiation at Jovian temperature conditions we can analyzethe color and spectral changes of the ice This enables us toevaluate NH SH as a candidate chromophore throughcomparisons of spectral slope and features found in ground-basedoptical spectra of Jupiter This work was supported by NASArsquosOuter Planets Research Program through grant numberNNX12AJ14G

Author(s) Alexander E Thelen Nancy Chanover MarkLoeffler Reggie Hudson Amy SimonInstitution(s) 1 NASA Goddard Space Flight Center 2 NewMexico State University

31127 ndash Helium Rain and the Thermal Evolution ofthe Jovian PlanetsThe atmospheres of Jupiter and Saturn are observed to be depletedin helium relative to the protosolar nebula Coupled with Saturnsdrastic overluminosity compared to homogeneous thermalevolution models this constitutes strong evidence that HHephase separation is underway within the deep interiors of bothplanets We compute thermal evolution models for Jupiter andSaturn adopting a recent HHe phase diagram based on ab initiosimulations We find that if He settles efficiently despiteconvection then differentiation contributes a significant amount ofluminosity It also establishes a composition gradient that tends tostabilize the fluid against convection between one and a few millionbars A steeper-than-adiabatic temperature gradient is thusrequired to deliver the planets intrinsic flux a feature whichprofoundly affects the thermal history and which has not beenaddressed in previous studies In this quasistable region weconsider two possibilities (i) that overturning convection persistsbut with decreased efficiency due to the added expense of mixingup heavier material and (ii) that overturning convection gives wayto overstable double-diffusive convection We will judge thesuccess of the adopted phase diagram along with these generalizedtheories of heat transport in matching the observed luminositiesand atmospheric He abundances of Jupiter and Saturnsimultaneously The models we develop will be poised toincorporate the upcoming Juno and Cassini gravity fieldmeasurements

Author(s) Christopher Mankovich Jonathan J Fortney Kevin L Moore Nadine NettelmannInstitution(s) 1 University of California Santa Cruz

31128 ndash Measurement Of The DH Abundance OnJupiter And Saturn Using The CIRS Far-IRInterferometerIt is believed that the majority of the hydrogen on Jupiter andSaturn was obtained when the solar system formed about 46 Gyrago Consequently knowing the DH abundance on Jupiter andSaturn is essential to understanding stellar nucleosynthesis in ourgalaxy and subsequently the composition of the primordial nebulaThe Composite Infrared Spectrometer (CIRS) aboard the Cassiniorbiter made observations of Jupiter in 2000-2001 and has beenmaking continuous observations of Saturn since 2004 at a 05 cmspectral resolution and covering all latitudes Utilizing this highspectral resolution we have sought to model the HD rotationaltransitions (S0 S1 S2 S3 at 8923 17784 26525 and 35088cm respectively) to retrieve the DH ratios on Jupiter and Saturnand show preliminary fitting to the far-IR spectral region using theCIRS FP1 far-IR interferometer This work will provide a newmeasurement of DH on the giant planets that will give improvedconstraint on formation and evolution models of the solar systemand other planetary systems

Author(s) J D Roberts-Pierel C A Nixon G L Bjoraker BE Hesman R K Achterberg P GJ Irwin F M FlasarInstitution(s) 1 CRESSTUMBC 2 NASA GSFC 3 OxfordUniversity 4 UMCP

31129 ndash Convective Origin of Long-Lived Spots on theGiant PlanetsIn an earlier paper (Chan and Mayr 2013 Earth and PlanetaryScience Letters 371-372 212-219) we discussed the generation oflong-lived cyclones and anticyclones in fast rotating convectionzones The mechnism was applied to explain phenomenon like theGreat Red Spot on Jupiter In those calculations only singlecompact vortices could be formed and generation of anticyclonescould only be realized in high latitude Similar problems exist incalculations by other authors (eg Kapyla et al 2011 ApJ 74234-41 Julien et al 2012 Geophys Astrophys Fluid Dyn 106392-428 Guervilly et al 2014 JFM 758 407-435) Here wepresent new calculations with higher aspect ratio (widthdepth = 8)showing that (i) anticyclones can be generated in low latitude (225degree N in our case) (ii) multiple cyclonesanticyclones can formin a single computational domain Besides demonstrating the

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prevalence of long-lived vortices in fast rotating convection zonesthe result also shows that aspect ratio of the domain is animportant factor in simulation implying its effect also onlaboratory experiments

Author(s) Kwing Lam Chan Hans G MayrInstitution(s) 1 Applied Physics Laboratory 2 Space ScienceInstitute Macau University of Science amp Technology

31130 ndash Evaluation of Data Used for Modelling theStratosphere of SaturnPlanetary atmospheres are modeled through the use of aphotochemical and kinetic reaction scheme constructed fromexperimentally and theoretically determined rate coefficientsphotoabsorption cross sections and branching ratios for themolecules described within them The KINETICS architecture haspreviously been developed to model planetary atmospheres and isapplied here to Saturnrsquos stratosphere We consider the pathwaysthat comprise the reaction scheme of a current model and updatethe reaction scheme according the to findings in a literatureinvestigation We evaluate contemporary photochemical literaturestudying recent data sets of cross-sections and branching ratios fora number of hydrocarbons used in the photochemical scheme ofModel C of KINETICS In particular evaluation of newphotodissociation branching ratios for CH C H C H C H C H and C H and new cross-sectional data for C H C H C H C H C H C H and C H are considered Byevaluating the techniques used and data sets obtained a newreaction scheme selection was drawn up These data are then usedwithin the preferred reaction scheme of the thesis and applied tothe KINETICS atmospheric model to produce a model of thestratosphere of Saturn in a steady state A total output of thepreferred reaction scheme is presented and the data is comparedboth with the previous reaction scheme and with data from theCassini spacecraft in orbit around SaturnOne of the key findings of this work is that there is significantchange in the modelrsquos output as a result of temperature dependentdata determination Although only shown within the changes tothe photochemical portion of the preferred reaction scheme it issuggested that an equally important temperature dependence willbe exhibited in the kinetic section of the reaction scheme Thephotochemical model output is shown to be highly dependent onthe preferred reaction scheme used within it by this thesis Theimportance of correct and temperature-appropriate photochemicaland kinetic data for the atmosphere under examination isemphasised as a consequence

Author(s) Eleanor Sophie Armstrong Patrick G J Irwin Julianne I MosesInstitution(s) 1 Space Science Institute 2 University of Oxford

31131 ndash Distribution of alkali gases in Ios atmosphereThanks to high-sensitivity (sub)millimeter spectroscopicobservations KCl and NaCl in gas phase have been detected at lowconcentration levels in Ios atmosphere These molecules are likelyto be the main potassium and sodium carriers from the moon to itsenvironment Indeed potassium and sodium are known to bepresent in Ios neutral clouds and plasma torus which are believedto be fed from the moon itselfThe immediate sources of gaseous NaCl and KCl in Iosatmosphere are still unknown Based on thermochemicalarguments both molecules could be present in volcanic plumesTheir lifetime in gaseous form is predicted to be rather low (a fewhours) and a large portion of the emitted gas should quicklycondense on the ground Sputtering of surface condensates byhigh-energy particles may re-inject some of the condensates backin the atmosphere The efficiency of this process is highlydependant on the local atmospheric column densityWe present maps of NaCl and KCl emission distribution obtainedin 2012 and 2015 with the Atacama Large Millimter Array (ALMA)The distribution maps will be compared to the distribution ofvolcanic centers and Ios bulk atmosphere (SO ) in an attempt tocharacterize their immediate sources

Author(s) Arielle Moullet Emmanuel Lellouch MarkGurwell Raphael Moreno John Black Bryan ButlerInstitution(s) 1 Chalmers University of Technology 2 LESIA-Observatoire de Paris 3 NRAO 4 NRAO 5 SAO-Center ForAstrophysics

31132 ndash The effect of large-scale tropospheric stormson the ionospheres of giant planetsIt is well recognized that large-scale storms in the Earthtroposphere can leave observable signatures in the structure of theionosphere in terms of local electron density distributionTerrestrial numerical models indicate that thunderstorms canchange the electron density by more than an order of magnitude(Shao et al 2012) The atmospheres of Jupiter and Saturn areriddled by atmospheric storms of all scales Lightning has beensuccessfully detected in optical images in the tropospheres of bothplanets Our work presents a theoretical study of the dynamical andelectromagnetic effects of large thunderstorms on the verticalplasma distribution in the ionospheres of Jupiter and Saturn andcompares the predicted signatures with the available electrondensity profiles from the Galileo and the Cassini missions

Author(s) Katia MatchevaInstitution(s) 1 University of Florida

31133 ndash Laboratory Measurements and Modeling ofMolecular Photoabsorption Cross Sections in theUltraviolet Diatomic Sulfur (S ) and Sulfur Monoxide(SO)Our research program comprises the measurement and modelingof ultraviolet molecular photoabsorption cross sections with thehighest practical resolution It supports efforts to interpret andmodel observations of planetary atmospheres Measurement andmodeling efforts on diatomic sulfur (S ) and sulfur monoxide (SO)are in progressS Interpretations of atmospheric (Io Jupiter cometary comae)S absorption features are hindered by a complete lack oflaboratory cross section data in the ultraviolet We are working toquantify the photoabsorption spectrum of S from 240 to 300 nmbased on laboratory measurements and theoretical calculationsWe have constructed an experimental apparatus to produce astable column of S vapor at a temperature of 800 KHigh-resolution measurements of the absorption spectrum of thestrong B ndash X system of S were completed using the NISTVUV-FTS at Gaithersburg MD These measurements are beingincorporated into a coupled-channel model of the absorptionspectrum of S to quantify the contributions from individual bandsand to establish the mechanisms responsible for the strongpredissociation signature of the B ndash X system A successful coupledchannels model can then be used to calculate the B ndash X absorptionspectrum at any temperatureSO There has been a long-standing need for high-resolution crosssections of SO radicals in the UV and VUV regions where themolecule strongly predissociates for modeling the atmospheres ofIo and Venus and for understanding sulfur isotope effects in theancient (pre-O ) atmosphere of Earth We have produced ameasurable column of SO in a continuous-flow DC discharge cellusing SO as a parent molecule Photoabsorption measurementswere recently recorded with the high-resolution VUV-FTS on theDESIRS beamline of the SOLEIL synchrotron A number of strongpredissociated SO bands were measured in the 140 to 200 nmregion Weaker features associated with the SO B ndash X system weresimultaneously recorded allowing for an approximatedetermination of the VUV SO band f-values

Author(s) Glenn Stark James Lyons Hannah Herde Gillian Nave Nelson de OliveiraInstitution(s) 1 Arizona State University 2 BrandeisUniversity 3 NIST 4 Synchrotron SOLEIL 5 WellesleyCollege

31134 ndash Measurement and modeling of cold CHspectra from 21 to 27 micromA new study of CH line intensities and positions in the Octad

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region between 3600 and 4800 cm will be reported Nine spectrawere recorded with two Fourier transform spectrometers (theMcMath-Pierce FTS at Kitt Peak Observatory and the Bruker 125HR FTS at the Jet Propulsion Laboratory) using C-enrichedsamples at temperatures from 299 K to 80 K Line positions andintensities were retrieved by non-linear least squares curve-fittingprocedures and analyzed using the effective Hamiltonian and theeffective Dipole moment expressed in terms of irreducible tensoroperators adapted to spherical top molecules Quantumassignments were found for all the 24 sub-vibrational states of theOctad (some as high as J=10) Over 4750 experimental linepositions and 3300 line intensities were fitted with RMS standarddeviations of 0004 cm and 69 respectively A new linelist ofover 9600 measured positions and intensities from 3607 to 4735cm was produced with known quantum assignments given for45 of the features A manuscript and database has beensubmitted to J Quant Spectrosc Radiat Transfer

Part of the research described in this paper was performed at theJet Propulsion Laboratory California Institute of TechnologyNASA Langley Research Center and Connecticut College undercontracts and cooperative agreements with the NationalAeronautics and Space Administration The support of theGroupement de Recherche International SAMIA between CNRS(France) and RFBR (Russia) is acknowledged

Author(s) Linda R Brown Keeyoon Sung Timothy JCrawford Andrei V Nikitin Sergeri A Tashkun Michael Rey Vladimir G Tyuterev Mary Ann H Smith Arlan MantzInstitution(s) 1 Dept of Physics Astronomy andGeophysicsConnecticutt College 2 Groupe de SpectromeacutetrieMoleacuteculaire et Atmospheacuterique Universiteacute de Reims 3 JetPropulsion Laboratory California Institute of Technology 4Laboratory of Theoretical Spectroscopy VE Zuev Institute ofAtmospheric Optics 5 Science Directorate Nasa Langley

31135 ndash Probing the Depths of Jupiter and Saturn atFive-MicronsBoth Jupiter and Saturn exhibit dramatic and dynamic changes atall levels of their atmospheres as probed at various wavelengthsfrom the cloud tops to the deeper atmosphere and through theirstratospheric changes One common thread that is evident is thatmany changes observed in the clouds seem to be initiated in thedeep atmospheres via the five micron spectral window on bothplanets based on the data acquired from the NASAInfraRedTelescope Facility (IRTF) Jupiter exhibits traditional 5-micron hotspots however their inventory varies with time Similar features atother latitudes (eg SEB) may indicate a similar mechanism atplay Another region that underwent global change is recent fade ofthe northern component of the North Equatorial Belt (NEBn) Itwas characterized by visible brown barges along its northernboundary that are partially clear but not as cloudless as 5-micronhot spots On Saturn long-term studies of thermal emission fromits atmospheric window between 51 and 52 microns revealed adetailed cloud structure representing variations of cloud opacityaround Saturnrsquos 2-3 bar pressure region that we have tracked since1995 Since that time the zonal-mean narrow dark bands haveremained constant and are correlated with variations of zonal jetsWe have identified long-term variations in the cloud opacity that doappear to be correlated with seasonal changes with a decrease ofzonal-mean cloud opacity strongly correlated with seasonalchanges in insolation Substantial perturbations to the atmospherein the northern hemisphere from the great storm of 2010-2011have led to significant perturbations of the deep cloud fielddetected at 51 microns The clouding over of the central stormtrack during early 2011 was followed by a central clearing andclouding over of regions to its north and south making the stormlatitude the clearest atmospheric region ever detected We willdiscuss these trends and others over time in particular radiancesdiscrete features for Saturn and present a comparison of thesetrends with high quality images from the amateur community toidentify correlationanitcorrelations of the visible cloud field

Author(s) Padma A Yanamandra-Fisher Sara MGutierrez Anna Payne Glenn S Orton James SinclairInstitution(s) 1 CITJet Propulsion Laboratory 2 SpaceScience Institute 3 University of California Berkeley 4 WelleslyCollege

312 ndash Future Missions Instruments andFacilities31201 ndash Historical trends of participation of womenin robotic spacecraft missionsFor many planetary scientists being involved in a spacecraftmission is the highlight of a career Many young scientists hope toone day be involved in such a mission We will look at the scienceteams of several flagship-class spacecraft missions to look fortrends in the representation of groups that are underrepresented inscience We will start with The Galileo Cassini and Europamissions to the outer solar system as representing missions thatbegan in the 1980s 1990s and 2010s respectively We would alsolike to extend our analysis to smaller missions and those to targetsother than the outer solar system

Author(s) Julie A Rathbun Luke Dones Pamela Gay Barbara Cohen Sarah Horst Emily Lakdawalla JamesSpickard Moses Milazzo Kunio M Sayanagi Joanna SchugInstitution(s) 1 College of William and Mary 2 HamptonUniversity 3 Johns Hopkins 4 NASA Marshall 5 SIUE 6southwest Research Institute 7 The Planetary Society 8 Univ ofRedlands 9 USGS Flagstaff

31202 ndash NASAs Planetary Data System Support forthe Delivery of Derived Data Sets at the AtmospheresNodeNASArsquos Planetary Data System is charged with archiving electronicdata products from NASA planetary missions that are sponsored byNASArsquos Science Mission Directorate This archive currentlyorganized by science disciplines uses standards for describing andstoring data that are designed to enable future scientists who areunfamiliar with the original experiments to analyze the data and todo this using a variety of computer platforms with no additionalsupport These standards address the data structure descriptioncontents and media design The new requirement in the NASAROSES-2015 Research Announcement to include a DataManagement Plan will result in an increase in the number ofderived data sets that are being delivered to the PDS These datasets may come from the Planetary Data Archiving Restoration andTools (PDART) program other Data Analysis Programs (DAPs) orbe volunteered by individuals who are publishing the results oftheir analysis In response to this increase the PDS AtmospheresNode is developing a set of guidelines and user tools to make theprocess of archiving these derived data products more efficientHere we provide a description of Atmospheres Node resourcesincluding a letter of support for the proposal stage acommunication schedule for the planned archive effort productlabel samples and templates in extensible markup language (XML)documentation templates and validation tools necessary forproducing a PDS4-compliant derived data bundle(s) efficiently andaccurately

Author(s) Nancy J Chanover Reta Beebe LynnNeakrase Lyle Huber Shannon Rees Danae HornungInstitution(s) 1 New Mexico State Univ

31203 ndash The Planetary Data System--preparing for aNew DecadeIn order to improve NASArsquos ability to serve the Planetary ScienceCommunity the Planetary Data System (PDS) has beentransformed NASA has used the highly successful virtual institutemodel (eg for NASArsquos Astrobiology Program) to re-compete theScience Nodes within the PDS Structure The new institutestructure will facilitate our efforts within the PDS to improve botharchive searchability and product discoverability We will continue

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the adaption of the new PDS4 Standard and enhance our ability towork with other archivecuration activities within NASA and withthe community of space faring nations (through the IPDA) PDSscience nodes will continue to work with NASA missions from theinitial Announcement of Opportunity through the end of missionto define organize and document the data This process includespeer-review of data sets by members of the science community toensure that the data sets are scientifically useful effectivelyorganized and well documentedThe Science nodes were selected through a Cooperative AgreementNotice (NNH15ZDA006C) which specifically allowed thecommunity to propose specific archive concepts The selectednodes are Cartography and Imaging Sciences Rings-MoonSystems Planetary Geosciences Planetary Plasma InteractionsAtmospheres and Small Bodies Other elements of the PDS includean Engineering Node the Navigation and Ancillary InformationFacility and a small project officeThe prime role of the PDS is unchanged We archive and distributescientific data from NASA planetary missions astronomicalobservations and laboratory measurements NASArsquos ScienceMission Directorate sponsors the PDS Its purpose is to ensure thelong-term usability of NASA data and to stimulate advancedresearchIn this presentation we discuss recent changes in the PDS and ourfuture activities to build on the new Institute Near term effortsinclude developing a PDS Roadmap for the next decade lead by PDSChief Scientist Dr Ralph McNutt We are actively seekingcommunity involvement in this process Please visit our UserSupport Area at the meeting if you have questions accessing ourdata sets or providing data to the PDS or about the new PDSstructure

Author(s) Thomas H Morgan William P Knopf Edwin JGrayzeckInstitution(s) 1 NASA HQ 2 NASAGSFC

31204 ndash Metadata Design in the New PDS4 Standards- Something for EverybodyThe Planetary Data System (PDS) archives supports anddistributes data of diverse targets from diverse sources to diverseusers One of the core problems addressed by the PDS4 datastandard redesign was that of metadata - how to accommodate theincreasingly sophisticated demands of search interfaces analyticalsoftware and observational documentation into label standardswithout imposing limits and constraints that would impinge on thequality or quantity of metadata that any particular observer or teamcould supply And yet as an archive PDS must have detaileddocumentation for the metadata in the labels it supports or theinstitutional knowledge encoded into those attributes will be lost -putting the data at riskThe PDS4 metadata solution is based on a three-step approachFirst it is built on two key ISO standards ISO 11179 InformationTechnology - Metadata Registries which provides a commonframework and vocabulary for defining metadata attributes andISO 14721 Space Data and Information Transfer Systems - OpenArchival Information System (OAIS) Reference Model whichprovides the framework for the information architecture thatenforces the object-oriented paradigm for metadata modelingSecond PDS has defined a hierarchical system that allows it todivide its metadata universe into namespaces (data dictionariesconceptually) and more importantly to delegate stewardship for asingle namespace to a local authority This means that a missioncan develop its own data model with a high degree of autonomyand effectively extend the PDS model to accommodate its ownmetadata needs within the common ISO 11179 framework Finallywithin a single namespace - even the core PDS namespace -existing metadata structures can be extended and new structuresadded to the model as new needs are identifiedThis poster illustrates the PDS4 approach to metadata managementand highlights the expected return on the development investmentfor PDS users and data preparers

Author(s) Anne C Raugh John S HughesInstitution(s) 1 Jet Propulsion Laboratory 2 University ofMaryland

31205 ndash SPICE Supports Planetary ScienceObservation GeometrySPICE is an information system comprising both data andsoftware providing scientists with the observation geometryneeded to plan observations from instruments aboard roboticspacecraft and to subsequently help in analyzing the data returnedfrom those observations The SPICE system has been used on themajority of worldwide planetary exploration missions since thetime of NASAs Galileo mission to Jupiter Along with its freeprice tag portability and the absence of licensing and exportrestrictions its stable enduring qualities help make it a popularchoice But stability does not imply rigidityndashimprovements andnew capabilities are regularly added This poster highlights recentadditions that could be of interest to planetary scientistsGeometry Finder allows one to find all the times or time intervalswhen a particular geometric condition exists (eg occultation) orwhen a particular geometric parameter is within a given range orhas reached a maximum or minimumDigital Shape Kernel (DSK) provides means to computeobservation geometry using accurately modeled target bodies atessellated plate model for irregular bodies and a digital elevationmodel for large regular bodiesWebGeocalc (WGC) provides a graphical user interface (GUI) to aSPICE geometry engine installed at a mission operations facilitysuch as the one operated by NAIF A WGC user need have only acomputer with a web browser to access this geometry engine Usingtraditional GUI widgetsndashdrop-down menus check boxes radiobuttons and fill-in boxesndashthe user inputs the data to be used thekind of calculation wanted and the details of that calculation TheWGC server makes the specified calculations and returns results tothe users browserCosmographia is a mission visualization program This toolprovides 3D visualization of solar system (target) bodies spacecrafttrajectory and orientation instrument field-of-view cones andfootprints and moreThe research described in this publication was carried out at the JetPropulsion Laboratory California Institute of Technology under acontract with the National Aeronautics and Space Administration

Author(s) Charles Hall Acton Nathaniel J Bachman BorisV Semenov Edward D WrightInstitution(s) 1 Jet Propulsion Laboratory

31206 ndash NASAs Asteroid Redirect Mission (ARM)The National Aeronautics and Space Administration (NASA) isdeveloping a robotic mission to visit a large near-Earth asteroid(NEA) collect a multi-ton boulder from its surface and redirect itinto a stable orbit around the Moon Once returned to cislunarspace in the mid-2020s astronauts will explore the boulder andreturn to Earth with samples This Asteroid Redirect Mission(ARM) is part of NASArsquos plan to advance the technologiescapabilities and spaceflight experience needed for a humanmission to the Martian system in the 2030s Subsequent humanand robotic missions to the asteroidal material would also befacilitated by its return to cislunar space Although ARM isprimarily a capability demonstration mission (ie technologies andassociated operations) there exist significant opportunities toadvance our knowledge of small bodies in the synergistic areas ofscience planetary defense asteroidal resources and in-situresource utilization (ISRU) and capability and technologydemonstrations In order to maximize the knowledge return fromthe mission NASA is organizing an ARM Investigation Teamwhich is being preceded by the Formulation Assessment andSupport Team These teams will be comprised of scientiststechnologists and other qualified and interested individuals to helpplan the implementation and execution of ARM An overview ofrobotic and crewed segments of ARM including the missionrequirements NEA targets and mission operations will beprovided along with a discussion of the potential opportunitiesassociated with the mission

2 12

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105

Author(s) Paul Abell Dan Mazanek David Reeves BoNaasz Benjamin CichyInstitution(s) 1 NASA Goddard Space Flight Center 2 NASAJohnson Space Center 3 NASA Langley Research Center

31207 ndash The Whipple Mission Exploring the KuiperBelt and the Oort CloudWhipple will characterize the small body populations of the KuiperBelt and the Oort Cloud with a blind occultation survey detectingobjects when they briefly (~1 second) interrupt the light frombackground stars allowing the detection of much more distantandor smaller objects than can be seen in reflected sunlightWhipple will reach much deeper into the unexplored frontier of theouter solar system than any other mission current or proposedWhipple will look back to the dawn of the solar system bydiscovering its most remote bodies where primordial processes lefttheir imprintSpecifically Whipple will monitor large numbers of stars at highcadences (~12000 stars at 20 Hz to examine Kuiper Belt events asmany as ~36000 stars at 5 Hz to explore deep into the Oort Cloudwhere events are less frequent) Analysis of the detected events willallow us to determine the size spectrum of bodies in the Kuiper Beltwith radii as small as ~1 km This will allow the testing of models ofthe growth and later collisional erosion of planetesimals in theearly solar system Whipple will explore the Oort Cloud potentiallydetecting objects as far out as ~10000 AU This will be the firstdirect exploration of the Oort Cloud since the original hypothesis of1950Whipple is a Discovery class mission that was proposed to NASA inresponse to the 2014 Announcement of Opportunity The missionis being developed jointly by the Smithsonian AstrophysicalObservatory Jet Propulsion Laboratories and Ball Aerospace ampTechnologies with telescope optics from L-3 Integrated OpticalSystems and imaging sensors from Teledyne Imaging Sensors

Author(s) Charles Alcock Michael Brown Tom Gauron Cate Heneghan Matthew Holman Almus Kenter RalphKraft John Livingstone Ruth Murray-Clay Paul Nulsen Matthew Payne Hilke Schlichting Amy Trangsrud JanVrtilek Michael WernerInstitution(s) 1 Caltech 2 Harvard-Smithsonian CfA 3 JPL4 MIT 5 UC Santa Barbara

31208 ndash Trojan Tour and Rendezvous (TTR) A NewFrontiers Mission to Conduct the First DetailedReconnaissance of the Jupiter Trojan AsteroidsAmong the most potentially diagnostic but least exploredpopulations of small bodies are the Jupiter Trojan asteroids whichorbit at ~5 AU in the L4 and L5 Lagrange points of Jupiter TheTrojans provide a unique perspective on solar system historybecause their locations and physical compositional andmineralogic properties preserve evidence for importantgravitational interactions among the giant planets The locationsand orbital properties of more than 6200 Jupiter Trojans are nowknown but that is likely only a small fraction of a population of upto ~1e6 Trojans gt1 km in size The Trojans are hypothesized to beeither former KBOs scattered into the inner solar system by earlygiant planet migration and then trapped in L4 and L5 or bodiesformed near 5 AU in a more quiescent early solar systemImportant Planetary Decadal Survey questions that can beaddressed by studying the Trojans include (a) How did the giantplanets and their satellite systems accrete and is there evidencethat they migrated to new orbital positions (b) What is therelationship between large and small KBOs Is the smallpopulation derived by impact disruption of the large one (c) Whatkinds of surface evolution radiation chemistry and surface-atmosphere interactions occur on distant icy primitive bodies And(d) What are the sources of asteroid groups (Trojans and Centaurs)that remain to be explored by spacecraftHere we describe the Trojan Tour and Rendezvous (TTR) NewFrontiers mission concept which is designed to answer theseDecadal questions and to test hypotheses for early giant planetmigration and solar system evolution Via close flybys of many ofthese objects and orbital characterization of at least one large

Trojan TTR will enable the initial up-close exploration of thispopulation Our primary mission goals are to characterize theoverall surface geology geochemistry and mineralogy of theseworlds to characterize their internal structure and dynamicalproperties to investigate the nature sources and history of activityon these bodies and to explore the diversity of the broader Trojanasteroid population

Author(s) James F Bell Cathy Olkin Julie Castillo-RogezInstitution(s) 1 Arizona State Univ 2 Jet PropulsionLaboratory Caltech 3 Southwest Research Inst

31209 ndash REASON for EuropaThe science goal of the Europa multiple flyby mission is to ldquoexploreEuropa to investigate its habitabilityrdquo One of the primaryinstruments selected for the scientific payload is a multi-frequencymulti-channel ice penetrating radar system This ldquoRadar for EuropaAssessment and Sounding Ocean to Near-surface (REASON)rdquowould revolutionize our understanding of Europarsquos ice shell byproviding the first direct measurements of its surface character andsubsurface structure REASON will address key questionsregarding Europarsquos habitability including the existence of anyliquid water through the innovative use of radar soundingaltimetry reflectometry and plasmaparticles analyses Theseinvestigations require a dual-frequency radar (HF and VHFfrequencies) instrument with simultaneous shallow and deepsounding that is designed for performance robustness in thechallenging environment of Europa The flyby-centric missionconfiguration is an opportunity to collect and transmit minimallyprocessed data back to Earth and exploit advanced processingapproaches developed for terrestrial airborne data sets Theobservation and characterization of subsurface features beneathEuroparsquos chaotic surface requires discriminating abundant surfaceclutter from a relatively weak subsurface signal Finally themission plan also includes using REASON as a nadir altimetercapable of measuring tides to test ice shell and ocean hypotheses aswell as characterizing roughness across the surface statistically toidentify potential follow-on landing sites We will present a varietyof measurement concepts for addressing these challenges

Author(s) Gerald Wesley Patterson Don Blankenship Alina Moussessian Jeffrey Plaut Yonggyu Gim DustinSchroeder Krista Soderlund Cyril Grima Elaine ChapinInstitution(s) 1 Jet Propulsion Laboratory California Instituteof Technology 2 Johns Hopkins University Applied PhysicsLaboratory 3 University of Texas Institute for Geophysics

31210 ndash MarsCAT Mars Array of ionosphericResearch Satellites using the CubeSat AmbipolarThrusterThe MarsCAT (Mars Array of ionospheric Research Satellites usingthe CubeSat Ambipolar Thruster) Mission is a two 6U CubeSatmission to study the ionosphere of Mars proposed for the NASASIMPLeX opportunity The mission will investigate the plasma andmagnetic structure of the Martian ionosphere including transientplasma structures magnetic field structure and dynamics andenergetic particle activity The transit plan calls for a piggy back ridewith Mars 2020 using a CAT burn for MOI the first demonstrationof CubeSat propulsion for interplanetary travel MarsCAT willmake correlated multipoint studies of the ionosphere and magneticfield of Mars Specifically the two spacecraft will make in situobservations of the plasma density temperature and convection inthe ionosphere of Mars They will also make total electron contentmeasurements along the line of sight between the two spacecraftand simultaneous 3-axis local magnetic field measurements in twolocations Additionally MarsCAT will demonstrate theperformance of new CubeSat telemetry antennas designed at theUniversity of Houston that are designed to be low profile ruggedand with a higher gain than conventional monopole (whip)antennas The two MarsCAT CubeSats will have five scienceinstruments a 3-axis DC magnetometer adouble-Langmuir probea Faraday cup a solid state energetic particle detector (ScienceEnhancement Option) and interspacecraft total electron contentradio occulation experiment The MarsCAT spacecraft will be solar

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powered and equipped with a CAT thruster that can provide up to48 kms of delta-V which is sufficient to achieve Mars orbit usingthe Mars 2020 piggyback They have an active attitude controlsystem using a sun sensor and flight-proven star tracker fordetermination and momentum wheels for 3-axis attitude control

Author(s) Edgar Andrew Bering Lawrence S Pinsky Liming Li David Jackson Ji Chen Helen Reed MarkMoldwin Justin Kasper J P Sheehan James RichardForbes Thomas Heine Anthony Case Michael Stevens DavidG SibeckInstitution(s) 1 HarvardSmithsonian Center for Astrophysics2 NASAGSFC 3 Texas AampM University 4 University ofHouston 5 University of Michigan

31211 ndash Linear Ion Traps in Space The Mars OrganicMolecule Analyzer (MOMA) Instrument and BeyondHistorically quadrupole mass spectrometer (QMS) instrumentshave been used to explore a wide survey of planetary targets in oursolar system from Venus (Pioneer Venus) to Saturn (Cassini-Huygens) However linear ion trap (LIT) mass spectrometers havefound a niche as smaller versatile alternatives to traditionalquadrupole analyzersThe core astrobiological experiment of ESArsquos ExoMars Program isthe Mars Organic Molecule Analyzer (MOMA) onboard theExoMars 2018 rover The MOMA instrument is centered on alinear (or 2-D) ion trap mass spectrometer As opposed to 3-Dtraps LIT-based instruments accommodate two symmetrical ioninjection pathways enabling two complementary ion sources to beused In the case of MOMA these two analytical approaches arelaser desorption mass spectrometry (LDMS) at Mars ambientpressures and traditional gas chromatography mass spectrometry(GCMS) The LIT analyzer employed by MOMA also offers higherion capacity compared to a 3-D trap of the same volume redundantdetection subassemblies for extended lifetime and a link toheritage QMS designs and assembly logistics The MOMAengineering test unit (ETU) has demonstrated the detection oforganics in the presence of wt-levels of perchlorate effective ionenhancement via stored waveform inverse Fourier transform(SWIFT) and derivation of structural information through tandemmass spectrometry (MSMS)A more progressive linear ion trap mass spectrometer (LITMS)funded by the NASA ROSES MatISSE Program is being developedat NASA GSFC and promises to augment the capabilities of theMOMA instrument by way of an expanded mass range (ie 20 ndash2000 Da) detection of both positive and negative ions spatiallyresolved (lt1 mm) characterization of individual rock core layersand evolved gas analysis and GCMS with pyrolysis up to 1300deg C(enabling breakdown of refractory phases) The AdvancedResolution Organic Molecule Analyzer (AROMA) instrumentbeing developed through NASA PICASSO and ESA Research andDevelopment Programs combines a highly capable LIT front end(a la LITMS) with a high-resolution Orbitrap (a laCosmOrbitrap) mass analyzer to enable disambiguation of complexmolecular signals in organic-rich targets

Author(s) Ricardo Arevalo William Brinckerhoff PaulMahaffy Friso van Amerom Ryan Danell Veronica Pinnick Xiang Li Lars Hovmand Stephanie Getty Andrej Grubisic Fred Goesmann Herveacute CottinInstitution(s) 1 CRESST University of Maryland BaltimoreCounty 2 CRESST University of Maryland College Park 3Danell Consulting Inc 4 Laboratoire Interuniversitaire desSystegravemes Atmospheacuteriques 5 Linear Labs LLC 6 Max-Planck-Institut fuumlr Sonnensystemforschung 7 Mini-Mass Consulting 8NASA Goddard Space Flight Center

31212 ndash Exploring near Earth objectrsquos activity withcubesats low surface brightnessEver smaller Near Earth Objects (NEOs) continue to be discoveredwith most potentially hazardous ones already surveyed andongoing plans for space missions to deflect and mine them in thenear future These transitional objects in relatively unstable orbitshave recently experienced collisional or dynamical encounters that

have sent them to Earthrsquos vicinity Finding comet-like activity(sublimation and ejected dust) is necessary to understand theirorigin recent history and evolution Mommert et al (2014) haverecently discovered cometary activity on the third largest NEO(3552) Don Quixote using near-Infrared imaging fromSpitzerIRAC they detect both a coma and tail as extendedemission they identify as CO ice sublimation This activity hasgone unnoticed due to either sporadic activity or the relatively lowsurface brightness in optical wavelengths of light reflecting off dust26 magarcsec which necessarily imposes an extreme bias againstdetection We propose to find this activity directly in the optical bygoing above the atmosphereWe are developing a 6U Cubesat to carry a 20cm aperturetelescope The volume restrictions impose a deployment systemdesign for the telescope We will study the optimal mission andoptical setup for our goals including the feasibility of a novelcoronagraph to increase the sensitivity Detecting NEO activityrequires stability and low instrumental noise over many hoursAtmospherersquos varying point spread function (PSF) coupled withthe extended PSF of reflective telescopes lead us to propose todevelop the concept and technology to manage a refractivetelescope in space with the potential inclusion of a coronagraphoptimized for detecting faint features near bright targets Theexperiment considers targeting nearby NEOs and optimizingobservations for low surface brightness

Author(s) Cesar Fuentes Marcos Diaz Claudio Falcon Marcel ClercInstitution(s) 1 Universidad de Chile

31213 ndash Fast Transit Access to the Outer Solar SystemWe explore the capability of a VASIMR reusable probe ldquocatapultrdquoconcept to send a 4000-5000 kg spacecraft to Jupiter on aHohmann-like transfer orbit arriving in just 36 months elapsedtime The VASIMR performs a slingshot pass close to the Sunand uses the high level of available solar energy to produce asustained burst of high thrust Enough kinetic energy is providedto the probe to reach Jupiter orbit within 07-14 AU The Catapultrelease the probe with enough speed to reach Jupiter in threeyears and returns to Earth for another mission This studyidentifies the important parameters in the probe ejector operation(power level propellant mass payload release point distance ofclosest approach to the Sun) and scan these parameters tounderstand and optimize the capabilities of the proposed systemWe assume that the Catapult and its payload begin at the Earthrsquossphere of influence (SOI) and are coasting in the Earthrsquos orbitabout the Sun The VASIMR enginersquos power rating must matchthe peak power available when the spacecraft is closest to the SunThe solar array is assumed to be a planar array rather than aconcentrator since it will have to operate near the Sun where aconcentrator would overheat photovoltaic cells The feasibility ofnot releasing the payload and using the VASIMR to providethrust for the duration of the transfer orbit will also be examinedIn this scenario the VASIMR RF generators could serve doubleduty as radar RF sources

Author(s) Jared Squire Edgar Bering MatthewGiambusso Mark Carter Andrew Ilin Franklin R Chang DiazInstitution(s) 1 AdAstra Rocket Company 2 University ofHouston

31214 ndash Modeling momentum transfer by the DARTspacecraft into the moon of DidymosThe Asteroid Impact and Deflection Assessment (AIDA) mission isa joint concept between NASA and ESA designed to test theeffectiveness of a kinetic impactor in deflecting an asteroid Themission is composed of two independent but mutually supportivecomponents the NASA-led Double Asteroid Redirect Test (DART)and the ESA-led Asteroid Impact Monitoring (AIM) mission Thespacecraft will be sent to the near-Earth binary asteroid 65803Didymos which makes unusually close approaches to Earth in2022 and 2024 These close approaches make it an ideal target for akinetic impactor asteroid deflection demonstration as it will beeasily observable from Earth-based observatories The ~2 m 300

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kg DART spacecraft will impact the moon of the binary system at625 kms The deflection of the moon will then be determined bythe orbiting AIM spacecraft and from ground-based observationsby measuring the change in the moonrsquos orbital period A modelingstudy supporting this mission concept was performed to determinethe expected momentum transfer to the moon following impactThe combination of CTH hydrocode models analytical scalingpredictions and N-body pkdgrav simulations helps to constrainthe expected results of the kinetic impactor experimentTo better understand the large parameter space (including materialstrength porosity impact location and angle) simulations of theDART impact were performed using the CTH hydrocode Theresultant crater size velocity imparted to the moon andmomentum transfer were calculated for all cases For ldquorealisticrdquoasteroid types simulated DART impacts produce craters withdiameters on the order of 10 m an imparted Δv of 05ndash2 mms anda dimensionless momentum enhancement (ldquobeta factorrdquo) of107ndash5 for targets ranging from a highly porous aggregate to a fullydense rock These results generally agree with predictions fromtheoretical and analytical studies Following impact pkdgravsimulations of the system evolution track changes in the orbitalperiod of the moon and examine the effects of the shapes ofDidymos and its moon on the deflection These simulationsindicate that the shapes of the bodies can influence the subsequentdynamics of the moon

Author(s) Angela M Stickle Justin A Atchison Olivier SBarnouin Andy F Cheng Carolyn M Ernst Derek CRichardson Andy S RivkinInstitution(s) 1 Johns Hopkins University Applied PhysicsLaboratory 2 University of Maryland

31216 ndash Fourier transform spectroscopy for futureplanetary missionsThermal-emission infrared spectroscopy is a powerful tool forexploring the composition temperature structure and dynamics ofplanetary atmospheres and the temperature of solid surfaces Ahost of Fourier transform spectrometers (FTS) such as MarinerIRIS Voyager IRIS and Cassini CIRS from NASA Goddard havemade and continue to make important new discoveries throughoutthe solar systemFuture FTS instruments will have to be more sensitive (when weconcentrate on the colder outer reaches of the solar system) andless massive and less power-hungry as we cope with decreasingresource allotments for future planetary science instruments Withthis in mind NASA Goddard was funded via the PlanetaryInstrument Definition and Development Progrem (PIDDP) todevelop CIRS-lite a smaller version of the CIRS FTS for futureplanetary missions Following the initial validation of CIRS-liteoperation in the laboratory we have been acquiring atmosphericdata in the 8-12 micron window at the 12 m telescope at theGoddard Geophysical and Astronomical Observatory (GGAO) inGreenbelt MD Targets so far have included Earths atmosphere(in emission and in absorption against the moon) and VenusWe will present the roadmap for making CIRS-lite a viablecandidate for future planetary missions

Author(s) John C Brasunas Tilak Hewagama John RKolasinski Theodor KostiukInstitution(s) 1 NASAS GSFC 2 University of Maryland

31217 ndash Planetary Science with the StratosphericObservatory for Infrared Astronomy (SOFIA)The Stratospheric Observatory for Infrared Astronomy (SOFIA) iscurrently conducting the third annual Cycle of guest investigatorobserving programs Programs selected for the fourth Cycle (2016)were announced in October The planetary science community hasmade a significant showing in all proposal Cycles comprisingapproximately 15 of the time awarded in Cycles 1-3 SOFIA offersobservers access to the complete infrared spectrum with much lessatmospheric absorption than from even the finest ground-basedtelescope sites New capabilities include high-resolutionspectroscopy in the mid-infrared with the Echelon-Cross-EchelleSpectrograph (EXES) that allows spectroscopy of molecules from

narrow stratospheric lines of planetary atmospheres plus imagingspectroscopy with the Field Imaging Far-Infrared LineSpectrometer (FIFI-LS) capable for example of simultaneousobservations in 9 spatial pixels in each of two far-infrared spectrallines Also the FLITECAM near-IR and FORCAST mid-IR camerasinclude grisms that allow moderate-resolution spectral imaging atwavelengths inaccessible from the ground and HIPO and FPI+high-speed photometric imagers are capable of high-SNmeasurements of stellar occultations and exoplanet transitsPlanetary science targets observed to date include comets ISONand PanSTARRS main belt asteroids Mars Jupiter NeptunePluto Europa exoplanets and debris disks This poster willshowcase science highlights give details regarding the SOFIAobservatory and instrument capabilities and present observingprogram statistics

Author(s) Dana E Backman William T ReachInstitution(s) 1 SOFIA

31218 ndash Capabilities of the Thirty-Meter Telescope(TMT) for Solar System AstronomyThe TMT will consist of a 30-m filled-aperture segmented primarymirror and will include non-sidereal rate tracking capabilities forobserving Solar System objects Its sensitivity will be 14 times largerthan that of 8-m class telescopes for seeing-limited observations-up to 200 times larger for background limited adaptive optics (AO)observations- and will allow high angularspatial resolution withdiffraction-limited capability in the near infrared AO guiding willaccommodate faint small angular size solar system objects to serveas natural guide stars for non-sidereal observations For Kuiperbelt objects (KBOs) on-instrument wavefront sensors can crawlthe field-of-view to look for background natural stars that can beused for tiptilt correction We will describe the maincharacteristics of the Thirty Meter Telescope its first lightinstrumentation suite and the most relevant science-drivenrequirements for its design emphasizing the strengths of the TMTfor Solar System astronomical research Some real-case scenariosof sensitivities for solar system targets will be presented for thefirst-light instrumentsComplementary information about TMT and the opportunities itoffers for planetary science research will be presented at thismeeting by Dumas et al and at the TMT Solar System Town Hallevent on TuesdayThe international TMT partnership includes Canada China IndiaJapan Caltech the University of California and Funding is alsoprovided by the Gordon and Betty Moore Foundation AURA is anAssociate Member of TMT on behalf of the US nationalcommunity Through a cooperative agreement with the NSF TMTand a US TMT Science Working Group are developing a model forpotential US national partnership in the TMT

Author(s) Angel Otarola Christophe Dumas KarenMeech Tomohiko Sekiguchi Warren Skidmore Feng Tian Tony Travouillon Michael H Wong Brent Ellerbroek LucSimardInstitution(s) 1 Institute for Astronomy University of Hawaii2 Hokkaido University of Education 3 TMT InternationalObservatory 4 Tsinghua University 5 University of California atBerkeley

31219 ndash The TMT International Observatory A quickoverview of future opportunities for planetary scienceexplorationThe construction of the Thirty-Meter-Telescope InternationalObservatory (TIO) is scheduled to take about eight years withfirst-light currently planned for the horizon 202324 and start ofscience operations soon after Its innovative design the unequalledastronomical quality of its location and the scientific capabilitiesthat will be offered by its suite of instruments all contribute toposition TIO as a major ground-based facility of the next decadeIn this talk we will review the expected observing performances ofthe facility which will combine adaptive-optics correctedwavefronts with powerful imaging and spectroscopic capabilitiesTMT will enable ground-based exploration of our solar system -

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3 5 33

108

and planetary systems at large - at a dramatically enhancedsensitivity and spatial resolution across the visible andnear-thermal- infrared regimes This sharpened vision spanningthe study of planetary atmospheres ring systems (cryondash)volcanicactivity small body populations (asteroids comets trans-Neptunian objects) and exoplanets will shed new lights on theprocesses involved in the formation and evolution of our solarsystem including the search for life outside the Earth and willexpand our understanding of the physical and chemical propertiesof extra-solar planets complementing TIOs direct studies ofplanetary systems around other starsTIO operations will meet a wide range of observing needsObserving support associated with classical and queue modeswill be offered (including some flavors of remote observing) TheTIO schedule will integrate observing programs so as to optimizescientific outputs and take into account the stringent observingtime constraints often encountered for observations of our solarsystem such as for instance the scheduling of target-of-oportunityobservations the implementation of short observing runs or thesupport of long-term key-science programmesComplementary information about TIO and the opportunities itoffers for planetary science research will be presented at thismeeting by Otarola et al in addition to the TMT Solar SystemTown Hall event on Tuesday

Author(s) Christophe Dumas Sandra Dawson AngelOtarola Warren Skidmore Gordon Squires TonyTravouillon Thomas K Greathouse Jian-Yang Li Junjun Lu Frank Marchis Karen J Meech Michael H WongInstitution(s) 1 California Institute of Technology 2 PlanetaryScience Institute 3 SETI Institute 4 Southwest Research Institute5 Thirty-Meter-Telescope International Observatory 6 UCBerkeley 7 University of Hawaii

31220 ndash The NASA Infrared Telescope Facility (IRTF)New Observational CapabilitiesThe NASA Infrared Telescope Facility (IRTF) is a 30-m infraredtelescope located at an altitude of 42 km near the summit ofMauna Kea on the island of Hawaii The IRTF was established byNASA to support planetary science missions Current instrumentsinclude (1) SpeX a 07-53 μm moderate resolution spectrographwith a slit-viewing camera that is also an imager (2) MORIS ahigh-speed CCD imager attached to SpeX for simultaneous visibleand near-infrared observations and (3) CSHELL a 1-5 μmhigh-resolution spectrograph MORIS can also be used as a visiblewavelength guider for SpeX Detector upgrades have recently beenmade to SpeX We discuss new observational capabilities resultingfrom completion of a new echelle spectrograph for 1-5 μm withresolving power of 70000 with a 0375 arcsec slit This instrumentwill be commissioned starting in the spring of 2016 We also plan torestore to service our 8-25 μm camera MIRSI It will be upgradedwith a closed-cycle cooler that will eliminate the need for liquidhelium and allow continuous use of MIRSI on the telescope Thiswill enable thermal observations of NEOs on short notice We alsoplan to upgrade MIRSI to have a simultaneous visible imager forguiding and for photometry The IRTF supports remote observingfrom any site This eliminates the need for travel to the observatoryand short observing time slots can be supported We also welcomeonsite visiting astronomers In the near future we plan toimplement a low-order wave-front sensor to allow real-time focusand collimation of the telescope This will greatly improveobservational efficiency For further information on the IRTF andits instruments including visitor instruments seehttpirtfwebifahawaiiedu We gratefully acknowledge thesupport of NASA contract NNH14CK55B NASA Science MissionDirectorate

Author(s) Alan T Tokunaga S J Bus Michael SConnelley John T RaynerInstitution(s) 1 Univ of Hawaii

31221 ndash The (new) Mid-Infrared Spectrometer andImager (MIRSI) for the NASA Infrared TelescopeFacility

The Mid-Infrared Spectrometer and Imager (MIRSI) wasdeveloped at Boston University and has been in use since 2002 onthe Infrared Telescope Facility (IRTF) making observations ofasteroids planets and comets in the 2 - 25 μm wavelength rangeRecently the instrument has been unavailable due to electronicsissues and the high cost of supplying liquid helium on MaunakeaWe have begun a project to upgrade MIRSI to a cryocooler-basedsystem with new array readout electronics and a dichroic andoptical camera to simultaneously image the science field for imageacquisition and optical photometry The mechanical cryocooler willenable MIRSI to be continuously mounted on the IRTF multipleinstrument mount (MIM) along with the other facility instrumentsmaking it available to the entire community for multi-wavelengthimaging and spectral observations We will propose to use therefurbished MIRSI to measure the 10 μm flux from Near EarthObjects (NEOs) and determine their diameters and albedosthrough the use of a thermal model We plan to observe up to 750NEOs over the course of a three year survey most of whosediameters will be under 300 meters Here we present an overviewof the MIRSI upgrade and give the current status of the projectThis work is funded by the NASA Solar SystemObservationsNEOO program

Author(s) Joseph L Hora David Trilling MichaelMommert Howard A Smith Nicholas Moskovitz Alan PMarscher Alan Tokunaga Lars Bergknut Morgan Bonnet Schelte J Bus Michael Connelly John Rayner DarrylWatanabeInstitution(s) 1 Boston University 2 Harvard-SmithsonianCfA 3 Lowell Observatory 4 Northern Arizona University 5University of Hawaii

31222 ndash Solar System science with the Large SynopticSurvey TelescopeThe Large Synoptic Survey Telescope (LSST httplsstorg) will bea large-aperture wide-field ground-based telescope that willsurvey half the sky every few nights in six optical bands from 320 to1050 nm It will explore a wide range of astrophysical questionsranging from performing a census of the Solar System toexamining the nature of dark energy It is currently in constructionslated for first light in 2019 and full operations by 2022The LSST will survey over 20000 square degrees with a rapidobservational cadence to typical limiting magnitudes of r~245 ineach visit (96 square degree field of view) Automated software willlink the individual detections into orbits these orbits as well asprecisely calibrated astrometry (~50mas) and photometry(~001-002 mag) in multiple bandpasses will be available as LSSTdata products The resulting data set will have tremendouspotential for planetary astronomy multi-color catalogs ofhundreds of thousands of NEOs and Jupiter Trojans millions ofasteroids tens of thousands of TNOs as well as thousands of otherobjects such as comets and irregular satellites of the major planetsLSST catalogs will increase the sample size of objects withwell-known orbits 10-100 times for small body populationsthroughout the Solar System enabling a major increase in thecompleteness level of the inventory of most dynamical classes ofsmall bodies and generating new insights into planetary formationand evolution Precision multi-color photometry will allowdetermination of lightcurves and colors as well as spin state andshape modeling through sparse lightcurve inversion LSST iscurrently investigating survey strategies to optimize science returnacross a broad range of goals To aid in this investigation we aremaking a series of realistic simulated survey pointing historiesavailable together with a Python software package to model andevaluate survey detections for a user-defined input populationPreliminary metrics from these simulations are shown here thecommunity is invited to provide further input

Author(s) Lynne Jones Mike Brown Zeljko Ivezić MarioJurić Renu Malhotra David TrillingInstitution(s) 1 CalTech 2 Lunar and Planetary Lab 3Northern Arizona University 4 Univ of Washington

31223 ndash The Space Launch System and Missions to

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4 1 44 2 3

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the Outer Solar SystemIntroduction Americarsquos heavy lift launch vehicle the SpaceLaunch System enables a variety of planetary science missionsThe SLS can be used for most if not all of the National ResearchCouncilrsquos Planetary Science Decadal Survey missions to the outerplanets The SLS performance enables larger payloads and fastertravel times with reduced operational complexityEuropa Clipper Our analysis shows that a launch on the SLSwould shorten the Clipper mission travel time by more than fouryears over earlier mission concept studiesJupiter Trojan Tour and Rendezvous Our mission conceptreplaces Advanced Stirling Radioisotope Generators (ASRGs) in theoriginal design with solar arrays The SLS capability offers manymore target opportunitiesComet Surface Sample Return Although in our missionconcept the SLS launches later than the NRC mission study(November 2022 instead of the original launch date of January2021) it reduces the total mission time including sample returnby two yearsSaturn Apmospheric Entry Probe Though Saturn arrivialtime remains the same in our concept as the arrival date in theNRC study (2034) launching on the SLS shortens the missiontravel time by three years with a direct ballistic trajectoryUranus Orbiter with Probes The SLS shortens travel time foran Uranus mission by four years with a Jupiter swing-by trajectoryIt removes the need for a solar electric propulsion (SEP) stage usedin the NRC mission concept studyOther SLS Science Mission Candidates Two other missionconcepts we are investigating that may be of interest to thiscommunity are the Advanced Technology Large Aperature SpaceTelescope (ATLAST) and the Interstellar Explorer also referred toas the Interstellar ProbeSummary The first launch of the SLS is scheduled for 2018followed by the first human launch in 2021 The SLS in its evolvingconfigurations will enable a broad range of exploration missionswhich will serve to recapture the enthusiasm and commitment thatpermeated the planetary exploration community during the earlyyears of robotic exploration

Author(s) Kurt K Klaus Kevin PostInstitution(s) 1 The Boeing Company

31224 ndash THEO Testing the Habitability ofEnceladusrsquos OceanSaturnrsquos moon Enceladus offers a unique opportunity in the searchfor life and habitable environments beyond Earth a key theme ofthe 2013 Decadal Survey as it informs our understanding of life andhabitability on our own planet by addressing (1) the limits of lifeunder colder fainter sun conditions (2) the importance ofhydrothermal alteration in the origin of life and (3) thedistribution of molecules in the solar system that may have servedas the precursors for life Plumes of predominately water vapor andice spew from the south pole of Enceladus Cassinirsquos data suggestthese plumes are sourced by a liquid reservoir beneath the moonrsquosicy crust that contains organics salts and water-rock interactionderivatives Thus the ingredients for life as we know itmdash liquidwater hydrocarbons and energy sourcesmdash are available inEnceladusrsquos subsurface ocean We only have to sample the plumesto investigate this hidden ocean environmentWith the help of TeamX the 2015 JPL Planetary Science SummerSchool student participants developed a proof of concept EnceladusNew Frontiers-class solar-powered orbiter The mission Testingthe Habitability of Enceladusrsquos Ocean (THEO) conducts remotesensing and in-situ analyses with the following instrument suite amass spectrometer a sub-mm radiometer-spectrometer a cameraand two magnetometers Measurements from these instrumentscan address four key questions for ascertaining Enceladean oceanhabitability within the context of the moonrsquos geological activityHow are the plumes and ocean connected Is there evidence ofbiological processes Are the abiotic conditions of the oceansuitable for habitability What mechanisms maintain the liquidstate of the ocean By taking advantage of the opportunityEnceladusrsquos plumes offer THEO represents a viable solar-poweredoption for exploring the potentially habitable ocean worlds of the

outer solar system This work was carried out at JPLCaltech undera contract with NASA

Author(s) Shannon MacKenzie Tess Caswell MatteoCrismani Kevin DeBruin Jasmeet Dhaliwal JasonHofgartner Akshata Krishnamurthy Kristen John CharityPhillips-Lander Cecilia Leung Joseph OrsquoRourke ElainePetro Samson Phan Kathryn Powell E Natasha Stavros Casey Steuer Vivian Sun Jut Wynne Charles Budney KarlMitchellInstitution(s) 1 Brown University 2 California Institute ofTechnology 3 Cornell University 4 CU Boulder 5 Jet PropulsionLaboratory California Institute of Technology 6 MassachusettsInstitute of Technology 7 NASA 8 Northern Arizona University9 Stanford University 10 University of Arizona 11 University ofCalifornia San Diego 12 University of Idaho 13 University ofMaryland 14 University of Michigan 15 University ofOklahoma 16 Washington University

31225 ndash Deliverable water from small NEOs to DRLOWe have developed a simplified mission model to estimate thequantity of deliverable water from small NEOs to distant retrogradelunar orbit (DRLO) as a function of Earth-return trip time and ΔvOur model is designed to be analytically simple computationallyefficient and close enough to optimal to provide a realistic butconservative assessment of the relevant parameters The challengestems from the fact that we are not considering a mission to aspecific known target but rather missions to the ensemble ofNEOs in a model population To further simplify the analysis wetreat Earths heliocentric orbit as circular with a semi-major axis of1 au and zero inclination

Author(s) Robert Jedicke Joel Sercel Karen Morenz Leslie S GertschInstitution(s) 1 Missouri University of Science and Technology2 TransAstra Corp 3 University of Hawaii 4 University ofToronto

31226 ndash Laboratory Spacecraft Data Processing andInstrument Autonomy AOSAT as TestbedRecent advances in small spacecraft allow for their use as orbitingmicrogravity laboratories (eg Asphaug and ThangavelauthamLPSC 2014) that will produce substantial amounts of data Powerbandwidth and processing constraints impose limitations on thenumber of operations which can be performed on this data as wellas the data volume the spacecraft can downlink We show thatinstrument autonomy and machine learning techniques canintelligently conduct data reduction and downlink queueing tomeet data storage and downlink limitations As small spacecraftlaboratory capabilities increase we must find techniques toincrease instrument autonomy and spacecraft scientific decisionmaking The Asteroid Origins Satellite (AOSAT) CubeSat centrifugewill act as a testbed for further proving these techniquesLightweight algorithms such as connected components analysiscentroid tracking K-means clustering edge detection convex hullanalysis and intelligent cropping routines can be coupled with thetradition packet compression routines to reduce data transfer perimage as well as provide a first order filtering of what data is mostrelevant to downlink This intelligent queueing provides timelierdownlink of scientifically relevant data while reducing the amountof irrelevant downlinked data Resulting algorithms allow forscientists to throttle the amount of data downlinked based oninitial experimental results The data downlink pipeline prioritizedfor scientific relevance based on incorporated scientific objectivescan continue from the spacecraft until the data is no longer fruitfulCoupled with data compression and cropping strategies at the datapacket level bandwidth reductions exceeding 40 can be achievedwhile still downlinking data deemed to be most relevant in a doubleblind study between scientist and algorithm Applications of thistechnology allow for the incorporation of instrumentation whichproduces significant data volumes on small spacecraft withoutcomparable increases to power and bandwidth budgets

1 1

12 14 5 11

3 6 715 10 2

13 9 16 514 1 8 5

5

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110

Author(s) Jack Lightholder Erik Asphaug JekanThangavelauthamInstitution(s) 1 Arizona State University

400 ndash Jovian Planet Atmospheres Stormsand Upper Atmosphere40001 ndash Spectral analysis of Uranusrsquo 2014 brightstorm with VLTSINFONIObservations by amateur observers of an extremely bright stormsystem in Uranusrsquo atmosphere in September 2014 triggered aninternational campaign to view this feature with many telescopesacross the world Near infrared observations of the storm systemwere acquired in OctoberNovember 2014 with SINFONI on ESOrsquosVery Large Telescope (VLT) in Chile SINFONI is an Integral FieldUnit spectrometer recording 64 times 64 pixel images with 2048wavelengthspixel using adaptive optics H-band (143 ndash 187 microm)image cubes were obtained at spatial resolutions of sim 01Prime perpixel The observations show that the centre of the storm featureshifts markedly with increasing altitude moving in the retrogradedirection and slightly poleward with increasing altitude A faint tailof more reflective material was also seen to the immediate south ofthe storm which again trails in the retrograde direction Theobserved spectra were analysed with the radiative transfer andretrieval code NEMESIS (Irwin et al 2008) We find that thestorm is well-modelled using either two main cloud layers of a5-layer aerosol model based on Sromovsky et al (2011) oremploying the simpler two-cloud-layer model of Tice et al (2013)The deep component appears to be caused by a brightening (ie anincrease in reflectivity) and increase in altitude of the maintropospheric cloud deck at 2 ndash 3 bars for both models while theupper component of the feature appears to be due to either athickening of the tropospheric haze of the 2-layer model or avertical extension of the upper tropospheric cloud of the 5-layermodel assumed to be composed of methane ice and based at theassumed methane condensation level at 123 bar For the 5-layermodel we also found this methane ice cloud to be responsible forthe faint lsquotailrsquo seen to the featurersquos south and the brighter polarlsquohoodrsquo seen in all observations polewards of sim 45degNDuring the twelve days between our sets of observations thehigher-altitude component of the feature was observed to havebrightened significantly and moved to even higher altitudes whilethe deeper component faded

Author(s) Patrick Gerard Joseph Irwin Leigh NFletcher Peter L Read Dane Tice Imke de Pater Glenn SOrton Nicholas A Teanby Gary R DavisInstitution(s) 1 Jet Propulsion Laboratory 2 Square KilometreArray Organisation 3 University of Bristol 4 University ofCalifornia Berkeley 5 University of Oxford

40002 ndash Bright features in Neptune on 2013-2015from ground-based observations with small (40 cm)and large telescopes (10 m)Observations of Neptune over the last few years obtained withsmall telescopes (30-50 cm) have resulted in several detections ofbright features on the planet In 2013 2014 and 2015 differentobservers have repeatedly observed features of high contrast atNeptunersquos mid-latitudes using long-pass red filters This success atobserving Neptune clouds with such small telescopes is due to thepresence of strong methane absorption bands in Neptunersquos spectraat red and near infrared wavelengths these bands provide goodcontrast for elevated cloud structures In each case theatmospheric features identified in the images survived at least a fewweeks but were essentially much more variable and apparentlyshorter-lived than the large convective system recently reported onUranus [de Pater et al 2015] The latest and brightest spot onNeptune was first detected on July 13th 2015 with the 22mtelescope at Calar Alto observatory with the PlanetCam UPVEHUinstrument The range of wavelengths covered by PlanetCam (from350 nm to the H band including narrow-band and wide-band filtersin and out of methane bands) allows the study of the vertical cloudstructure of this bright spot In particular the spot is particularly

well contrasted at the H band where it accounted to a 40 of thetotal planet brightness Observations obtained with smalltelescopes a few days later provide a good comparison that can beused to scale similar structures in 2013 and 2014 that wereobserved with 30-50 cm telescopes and the Robo-AO instrument atPalomar observatory Further high-resolution observations of the2015 event were obtained in July 25th with the NIRC2 camera inthe Keck 2 10-m telescope These images show the bright spot as acompact bright feature in H band with a longitudinal size of 8300km and a latitudinal extension of 5300 km well separated from anearby bright band The ensemble of observations locate thestructure at -41ordm latitude drifting at about +2427ordmday or -923 msconsistently with the zonal winds This work demonstratesexcellent opportunities for pro-am collaboration in the study ofNeptune and the value of nearly continuous monitoring of theplanet by a broad network of amateur collaborators

Author(s) Ricardo Hueso Marc Delcroix ChristophBaranec Agustiacuten Saacutenchez-Lavega Josep Mariacutea Goacutemez-Forrellad Jose Feacutelix Rojas Statia Luszcz-Cook Imke dePater Katherine de Kleer Franccedilois Colas Joan Guarro Peter Goczynski Paul Jones Willem Kivits Paul Maxson Michael Phillips John Sussenbach Anthony Wesley Heidi BHammel Santiago Peacuterez-Hoyos Intildeigo Mendikoa ReedRiddle Nicholas M Law Kunio SayanagiInstitution(s) 1 American Museum of National History 2Association of Universities for Research in Astronomy 3California Institute of Technology 4 Fundacioacute Observatori EsteveDuran 5 Hampton University 6 IMCCE Observatoire de Paris7 International Outer Planets Watch Planetary VirtualObservatory Laboratory 8 Socieacutete Astronomique de France 9Universidad del Paiacutes Vasco 10 University of California 11University of Hawaii at Manoa 12 University of North Carolina

40003 ndash An endurign rapidly moving storm as aguide to Saturns equatorial jet complex structureSaturn has an intense and broad eastward equatorial jet at cloudlevel whose variability and meridional and vertical structure arecomplex and actively debated Due to its 27ordm rotation axis tilt andorbital eccentricity Saturn is under a strong seasonal insolationcycle enhanced at equator by the ring shadowing periods Thesefactors make it a good natural laboratory to test models ofequatorial jet generation in giant planets We report on a brightequatorial storm at 6 degrees North latitude observed in 2015 thatmoved rapidly but steadily at a high speed of 450 ms notreported since Voyagers times (Sanchez-Lavega et al Icarus 147405-420 2000) Imaging with the Hubble Space Telescope (HST)WFC3 showed detailed storm morphology at red wavelengths (689750 and 937 nm) confirming its high speed Other equatorialclouds moved with lower velocities matching the Cassini ISS profile(Garciacutea-Melendo et al Icarus 215 62-74 2011) while the stormmatches the Voyager 1 and 2 profile We interpret this result as thesimultaneous detection of the wind profile at two separated altitudelevels within the cloud layer In addition the HST methane bandand ultraviolet images allowed retrieving winds at a third altitudelevel of motion in the haze layer above the cloud deck Combiningthe current wind data with previous dates allowed us to construct avertical ndash meridional section of the structure of Saturnrsquos equatorialjet at cloud level We discuss the implications of these results onthe long-term stability of Saturnrsquos equatorial jet

Author(s) Agustin Sanchez-Lavega Mike H Wong AmySimon Ricardo Hueso Santiago Perez-Hoyos ArrateAntuntildeano Jose Felix Rojas Teresa del Rio-Gaztelurrutia Naiara Barrado-Izagirre Itziar Garate-Lopez Enrique Garcia-Melendo Jose Francisco Sanz-Requena Josep Maria Gomez-Forrellad Imke de PaterInstitution(s) 1 Fundacioacute Observatori Esteve Duran 2 NASAGoddard Space Flight Center 3 Universidad del Pais VascoUPVEHU 4 Universidad Europea Miguel de Cervantes 5University of California

40004 ndash The Clearing of Ammonia and Deeper Cloudsin the Wake of Saturns Great Storm of 2010-2011

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Saturns Great Storm of 2010-2011 produced a planet-encirclingwake that slowly transitioned from a region that was mainly dark at5 microns in February 2011 to a region that was almost entirelybright and remarkably uniform by January 2012 (Momary andBaines 2014 AASDPS Meeting Abstracts) The uniformity andhigh emission levels suggested that the entire wake region hadbeen cleared not only of the ammonia clouds that the storm hadgenerated but also of deep aerosols that normally providesignificant blocking of the thermal emission from Saturns warmerdeep atmosphere Measurements of 22-cm emission in May 2011(Jannsen et al 2013 Icarus 226 522-535 Laraia et al 2013 Icarus226 641-654) showed that the wake region was becoming driedout with respect to ammonia vapor suggesting that a depletion ofNH clouds might be occurring Our analysis of VIMS spectra fromDecember 2012 confirmed a clearing of NH particles but showedthat two significant cloud layers remained behind about 5 opticaldepths (at 2 microns) in a 120-530 mbar layer (needed to matchlevels of reflected sunlight) and an optically thick cloud near 35bars (needed to limit 5-micron thermal emission) From spectrataken from the same latitude region upstream of the storm inFebruary 2011 we inferred a similar cloud structure with the mainexception being that the deep thermal blocking layer likelycomposed of NH SH particles was more spatially variable and at alower effective pressure (29 bars vs 35 bars) reducing 5-micronemission by a factor of 2 or more relative to the cleared region inthe wake While the storm head and early wake region displayedstrong signatures of ammonia ice these were not present prior tothe storm and disappeared completely as part of the wake clearingevent The main reason for the high 5-micron brightness of thecleared region is the removal of cloud particles in the regionbetween about 500 mbar and 35 bars Its exceptional horizontaluniformity remains to be explainedThis research was supported by a grant from NASAs CDAPSprogram

Author(s) Lawrence A Sromovsky Kevin H Baines Patrick M FryInstitution(s) 1 Univ of Wisconsin Madison

40005 ndash The Evolution of Saturnrsquos Storm-PerturbedLatitudinal Band Determined from CassiniVIMSDaytime and Nighttime SpectraSaturnrsquos Great Storm of 2010-2011 was one of the most powerfulconvective events ever witnessed as indicated for example by itsability to deliver spectrally-identifiable water ice to the top of itsconvective tower ~200 km above the water vapor condensationlevel near 20 bar (Sromovsky L A et al Icarus 226 402-4182013) and by its ability over ~ 6 months to encircle the planet withapparently anvil-like ammonia clouds sheared away from the top ofits convective tower(s) Within a half-year after the storm subsidedin mid-2011 these globe-encircling anvil-like clouds appeared tohave largely disappeared replaced by a 5-micron-bright bandencircling the planet over nearly the same latitude region the stormgenerated clouds had been indicating a dramatic decrease in theopacity of aerosols sensitive to 5-micron radiation (heat)emanating from the warm depths of the planet Here we presentquantitative results on the 5-year evolution of this storm-affected5-micron-bright region from its initial appearance associated witha large anti-cyclone that formed in the Spring of 2011 through May26-27 2015 using both daytime and nighttime CassiniVIMSspectral maps Compared to the ldquonormalrdquo unperturbed regionalcloud structure upstream of the storm as observed on Feb 24 2011we find that the initial 5-micron-bright region on May 11 2011 hadlost ~60 of its upper-cloud (100-500 mbar) opacity (i enominally 27 opacity post-storm at 2-microns vs 71 pre-storm)and that the pressure of an opaque putatively NH SHoptically-thick ldquosheetrdquo cloud dropped in altitude from a pre-stormlevel of 29 bar to the 32-bar level post-storm Subsequently overthe next 4 years the upper-cloud region recovered half of its lostopacity reaching ~56 on March 21 2014 (and nearly recovered to~ 7 in our tentative May 26-27 2015 data) corresponding to ane-folding time back to pre-storm opacity of 27 years but the lowercloud has dropped down to the 33-bar level (rising to ~ 30 bar inour tentative analysis of the May 2015 data) Throughout the

region has remained 5-micron-bright predominantly due to thedeeper warmer level of the opaque putative NH SH cloud

Author(s) KH Baines Larry A Sromovsky Patrick M Fry Thomas W Moimary Sarah Badman Robert H Brown BonnieJ Buratti Roger N Clark Philip D Nicholson Christophe SotinInstitution(s) 1 Cornell University 2 Lancaster University 3NASAJet Propulsion Laboratory 4 Planetary Science Institute 5SSECUniversity of Wisconsin-Madison 6 University of Arizona

40006 ndash Shallow Water Simulations of the Three LastSaturns Giant StormsShallow Water (SW) simulations are used to present a unifiedstudy of the polar (1960) equatorial (1990) and mid-latitude(2010) major storms in Saturn nicknamed as Great White Spots(GWS) The 2010 GWS appeared at +40 moved at -30 m s-1 wherethe Coriolis force is predominant producing an open anticyclonewith a high speed peripheral circulation and a cloud front aroundthe convective source a long-lived anticyclone and strong zonaladvection on the south part of the storm forming a turbulentregion The 1990 GWS onset took place near the equator between+12 and +5 on the broad prograde equatorial jet (450 m s-1) whereequatorial dynamics dominated producing a storm nucleus withrapid expansion to the west of a Kelvin-Helmholtz instability onthe north side of the perturbation due to advection and trappedequatorial waves which also expanded the storm to the east aroundthe equator The 1960 GWS appeared at high latitudes (+56) whereCoriolis force is predominant in a region where zonal wind velocityis 0 m s-1 SW simulations predict a strong injection of relativevorticity which may produce large anticyclones on the anticyclonicside of the zonal profile and a quick turbulent expansion on thebackground cyclonic regions at mid and high latitudes In generalsimulations indicate that negative relative vorticity injected by thestorms also defines the natural interaction with the zonal winds atlatitudes where the Coriolis force is dominant dictating its largescale dynamical behavior Numerical experiments on the 1990storm indicate that the onset of the storm can only be reproduced ifthe Voyager era background zonal flow is used which suggests thatit dominated the circulation dynamics at the stormrsquos outbreakregion at that time They also reproduce its most importantmorphological features and show the production of planetarywaves and turbulence We discuss possible mechanism for theobserved equatorial jet alterations during the storm expansion

Author(s) Enrique Garcia-Melendo Agustin Sanchez-LavegaInstitution(s) 1 Fundacio Observatori Esteve Duran 2University of the Basque Country

40007D ndash Theoretical estimation of the radiativecooling rate in the Jovian troposphereJupiter exhibits characteristic cloud activities but their physicalmechanism remains poorly understood Recently Sugiyama et al(2014) demonstrated that the Jovian cloud convection may have asignificant intermittency in the generation of cumulonimbusclouds with the typical interval length controlled by the radiativecooling rate in the upper troposphere In spite of such importanceas a controlling factor of cloud activity the tropospheric radiativecooling rate profile has never been systematically quantified for theJovian system In the Jovian troposphere condensable species(NH H S H O) and their condensates might significantlycontribute to radiative transferHere we show numerical estimates of radiative cooling rate profileunder Jovian troposphere condition by using our non-grayradiative transfer model that contains optical properties of gasspecies (H He H O CH NH H S and PH ) and cloud layersmade of H O NH SH and NH ice particles The temperatureprofile is determined by the radiative-convective equilibrium statesatisfying an observed potential temperature of Joviantroposphere The mean vertical distributions of gas and cloud aregiven on the basis of the latest hydrodynamic simulation of Joviancloud convection (Sugiyama et al 2014) and cosmochemicalconsiderationThe modeled atmosphere has the tropopause at ~038 bar level

33

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The radiative cooling rate reaches the maximum 15 x 10 KJovianday at ~05 bar level then decreases with depth and approacheszero below 5 bar level This profile is largely determined by thethermal absorption and emission due to gaseous NH and H witha slight modification by solar heating due to CH The cloud layersare found to have only a weak effect on either radiative cooling orheating because their opacities in the longwave radiation areestimated to be very small which agrees with the observed5-micron spectrum with high brightness temperatures Theuncertainty in H O abundance in deep troposphere would notaffect the radiative cooling because H O mostly condenses out inthe deep region with large optical depths for longwave radiation

Author(s) Yasuto Takahashi George L Hashimoto MasakiIshiwatari Yoshiyuki O Takahashi Ko-ichiro Sugiyama Masanori Onishi Kiyoshi KuramotoInstitution(s) 1 Hokkaido University 2 ISASJAXA 3 KobeUniversity 4 Okayama University

40008D ndash Seasonal evolution of SaturnsstratosphereThe exceptional duration of the Cassini-Huygens mission enablesunprecedented study of Saturns atmospheric dynamics andchemistry In Saturns stratosphere (from 20 hPa to 10 hPa)photochemical and radiative timescales are in the same order asSaturns revolution period (295 years) Consequently the largeseasonal insolation variations experienced by this planet areexpected to influence significantly temperatures and abundances ofphotochemical by-products in this region We investigate theseasonal evolution of Saturns stratosphere by measuringmeridional and seasonal variations (from 2005 to 2012) oftemperature and C H C H and C H abundances usingCassiniCIRS limb observations We complete this study with thedevelopment of a GCM (Global Climate Model) in order tounderstand the physical processes behind this seasonal evolutionThe analysis of the CIRS limb observations show that the lower andupper stratospheres do not exhibit the same trends in theirseasonal variations especially for temperature In the lowerstratosphere the seasonal temperature contrast is maximal (at 1hPa) and can be explained by the radiative contributions includedin our GCM In contrast upper stratospheric temperatures (at 001hPa) are constant from northern winter to spring at odds with ourGCM predictions This behavior indicates that other physicalprocesses such as gravity waves breaking may be at play At 1 hPaC H C H and C H abundances exhibit a striking seasonalstability consistently with the predictions of the photochemicalmodels of Moses and Greathouse 2005 and Hue et al 2015However the meridional distributions of these species do notfollow the predicted trends which gives insight on atmosphericdynamics We perform numerical simulations with the GCM tobetter understand dynamical phenomena in Saturns atmosphereWe investigate how the large insolation variations induced by theshadow of the rings influence temperatures and atmosphericdynamics We also study the characteristics of atmospheric wavesin the numerical simulations and compare them to existingobservations (Achterberg and Flasar 1996 Orton et al 2013)

Author(s) Melody Sylvestre Thierry Fouchet AymericSpiga Sandrine GuerletInstitution(s) 1 Laboratoire de Meacuteteacuteorologie DynamiqueUniversiteacute Pierre et Marie Curie 2 LESIA - Observatoire de Paris

401 ndash Marss Atmosphere and Surface40101 ndash Mars Science Laboratorys rover CuriosityOngoing investigations into the habitability of MarsNASArsquos Curiosity rover has the objective to determine whetherMars was habitable The roverrsquos science team has achieved that andmore including two major firsts in planetary science First GaleCrater was determined to once have an aqueous environment andable to support microbial life evidenced by conglomerates and thedetailed analyses of the drill samples [1] Second the age dating ofrock on another planet ndash radiogenic and cosmogenic noble gases in

a mudstone yielded a K-Ar age of 421 plusmn 035 Ga while 3He 21Neand 36Ar yielded surface exposure ages of 78 plusmn 30 Ma [2]suggesting the potential to find rocks whose organic content hasnot yet been destroyed by cosmic rays Indeed organic compoundshave been found in samples from the Sheepbed mudstone [3]Reports of plumes of methane in the martian atmosphere havedefied explanation to date Curiosity measured a constantbackground level of atmospheric methane with a mean value of069 plusmn 025 ppbv consistent with methane released from thedegradation of interplanetary dust and meteorites However infour consecutive measurements spanning two months the rovermeasured a ten-fold increase (72 plusmn 21 ppbv) suggesting thatmethane was actively added from an unknown source [3] Periodicmeasurements will continue perhaps revealing the possiblesources of high methane whether biological or abiologicalEnhancing our concept of Marsrsquo capability to support life theCuriosity rover has detected nitrogen-bearing compounds of110ndash300 ppm of nitrate in scooped sand and 70ndash1100 ppm ofnitrate in drilled mudstone Discovery of martian nitrogen hasimportant implications for a nitrogen cycle at some point inmartian history [4] More recent exploration has focused on theinvestigation of a mudstone-sandstone geologic contact high Siand H abundances and organics These and the latest results fromCuriosity will be discussed exploring the transition of Mars from ahabitable world to the desert planet it is today [1] Grotzinger et alScience 343 388 (2014) [2] Farley et al Science 343 389 (2014)[3] Feissinet et al JGR 120 495-514 (2015) [3] Webster et alScience 347 415-427 (2015) [4] Stern et al PNAS 1124245-4250 (2015)

Author(s) Michael Meyer Ashwin VasavadaInstitution(s) 1 JPL 2 NASA HQ

40102 ndash Liquid Water Lakes on Mars UnderPresent-Day Conditions Sustainability and Effects onthe SubsurfaceDecades of Mars exploration have produced ample evidence thataqueous environments once existed on the surface Much evidencesupports groundwater emergence as the source of liquid water onMars [1-4] However cases have also been made for rainfall [5] andsnow pack melts [6]Whatever the mechanism by which liquid water is emplaced on thesurface of Mars whether from groundwater seeps atmosphericprecipitation or some combination of sources this water wouldhave collected in local topographic lows and at least temporarilywould have created a local surface water system with dynamicthermal and hydrologic properties Understanding the physicaldetails of such aqueous systems is important for interpreting thepast and present surface environments of Mars It is also importantfor evaluating potential habitable zones on or near the surfaceIn conjunction with analysis of surface and core samples valuableinsight into likely past aqueous sites on Mars can be gainedthrough modeling their formation and evolution Toward that endwe built a 1D numerical model to follow the evolution of smallbodies of liquid water on the surface of Mars In the model liquidwater at different temperatures is supplied to the surface atdifferent rates while the system is subjected to diurnally andseasonally varying environmental conditions We recentlysimulated cases of cold (275 K) and warm (350 K) water collectingin a small depression on the floor of a mid southern latitude impactcrater When inflows create an initial pool gt 3 m deep andinfiltration can be neglected we find that the interior of the poolcan remain liquid over a full Mars year under the present cold anddry climate as an ice cover slowly thickens [7] Here we present newresults for the thermal and hydrologic evolution of surface waterand the associated subsurface region for present-day conditionswhen infiltration of surface water into the subsurface is considered[1] Pieri (1980) Science 210[2] Carr (2006) The Surface of Mars[3] Wray et al (2011) J Geophys Res 116[4] Michalski et al (2013) Nature Geosci 6[5] Craddock and Howard (2002) J Geophys Res 107[6] Clow (1987) Icarus 72[7] Goldspiel (2015) Astrobio Sci Conf Abs 7110

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Author(s) Jules M GoldspielInstitution(s) 1 Planetary Science Institute

40103 ndash CO -driven formation of gullies on MarsSince their discovery by the Mars Observer Camera Martian gullieshave attracted considerable attention because they resembleterrestrial debris flows formed by the action of liquid water Thisinterpretation is now questioned by the discovery of ongoing gullyformation occurring in conditions much too cold for liquid waterbut with seasonal CO frost present and defrosting However howa relatively thin seasonal dry ice cover could trigger the formationof decameter large debris flows exhibiting levees and sinuosities asif they were liquid-rich remained mysteriousWe have developed an innovative thermo-physical model of theMartian soil able to compute the seasonal evolution of a columncomposed of an underlying regolith a CO ice layer and theatmosphere above Below the surface in the CO ice layer (whenpresent) and in the regolith the model simultaneously solves theheat conduction the radiative transfer through the ice as well asthe diffusion condensation and sublimation of CO and the relatedlatent heat exchangesWe have found that during the defrosting season the pores belowthe ice layer can be filled with CO ice and subject to extremepressure variations The subsequent gas fluxes can destabilize thesoil and create gas-lubricated debris flows with the observedgeomorphological characteristics of the Martian gullies Inparticular the viscosity of such flows can be estimated to rangefrom a few tens to a few thousands of Pas similar to watertriggered debris flows and consistent with previous calculations onMartian gullies Importantly these gas fluidized debris flows canoccur below the theoretical angle of repose which has been aconcern in the understanding of gully landforms formation Wealso performed model calculations for a wide range of latitudes andslope orientations These simulations reveal that high-pressureCO gas trapping in the subsurface and the subsequent formationof ice within the regolith pores are predicted at latitudes and slopeorientations where gullies are observed and not elsewhere Inparticular the model explains why gullies are only observed on polefacing slopes between 30deg and 45deg latitude and with no orientationpreference above 45deg latitude

Author(s) Cedric Pilorget Franccedilois ForgetInstitution(s) 1 Institut dAstrophysique Spatiale 2Laboratoire de Meteorologie Dynamique

40104 ndash The Coupled Water-Dust Cycles on Mars AnInvestigation of Cloud Formation UsingMarsCAM-CARMAVariability in the present day Martian climate is dominated by theimpact of atmospheric dust On Earth mineral dust is a well knownnucleation site for high altitude cirrus clouds Similarly tenuouswater ice and carbon dioxide clouds have been observed on MarsTheir impact is expected to be large but is historically difficult tomodel accurately Here we present results from the NCARCommunity Atmosphere Model for Mars (MarsCAM) coupled witha physically based state-of-the-art cloud and dust physics packagedeveloped for Earth the Community Aerosol and Radiation Modelfor Atmospheres (CARMA) Directly modeling heterogeneousnucleation on a time varying fully interactive dust field provides afirst step to better understanding the formation distribution andcompostion of clouds on present day and early Mars

Author(s) Victoria Hartwick O Brian ToonInstitution(s) 1 University of Colorado - Boulder

40105 ndash Reduced Baroclinicity During Martian GlobalDust StormsThe eddy kinetic energy equation is applied to the Mars AnalysisCorrection Data Assimilation (MACDA) dataset during thepre-winter solstice period for the northern hemisphere of MarsTraveling waves are triggered by geopotential flux convergencegrow baroclinically and decay barotropically Higher optical depthincreases the static stability which reduces vertical and meridionalheat fluxes Traveling waves during a global dust storm year

develop a mixed baroclinicbarotropic growth phase beforedecaying barotropically Baroclinic energy conversion is reducedduring the global dust storm but eddy intensity is undiminishedInstead the frequency of storms is reduced due to a stabilizedvertical profile

Author(s) Joseph Battalio Istvan Szunyogh MarkLemmonInstitution(s) 1 Texas AampM University

40106 ndash The effect of a temperature-dependentcontact parameter on Mars cloud formationModeling the current water cycle on Mars is a complex problemthat at present remains a scientific challenge The water cycle ishighly coupled to atmospheric temperature dust surface icetemperature atmospheric transport and mixing (ie planetaryboundary layer (PBL) processes and radiation just to name a fewOne of the main features of Mars water cycle is the formation ofthe aphelion cloud belt Clouds are formed at altitude (10-40 km)within the subtropics during the aphelion season (Ls=60deg-120deg)In general the aphelion cloud belt forms at higher altitudescompared to the polar and high-latitude clouds and therefore atcolder temperatures (180 K and below) Laboratory experiments ofnucleation under cold temperatures indicate that nucleationbecomes more difficult at and below 180 K than expected This canbe modeled by using a temperature-dependent contact parameterm(T) In this study we use the NASA Ames Mars Global CirculationModel (Mars GCM) to compare the constant contact parameterwith the temperature-dependent contact parameterizationdescribed by Iraci et al (2010) The simulations demonstrate thatthe contact parameter has a significant affect on the opacity of theaphelion clouds as well as the clouds that form at the edge of theseasonal CO ice caps Both types of clouds tend to form near 180K supporting the importance of a temperature-dependent contactparameter

Author(s) Richard Atsuki Urata Jeffery Hollingsworth Melinda KahreInstitution(s) 1 Bay Area Environmental Research 2 NASAAmes Research Center

40107 ndash CRISM Limb Observations of Coincident COIce Clouds and O Emission in the Mars EquatorialMesosphereLimb observations with the CRISM visiblenear IR (04-4 μm)imaging spectrometer (Murchie et al 2009) onboard the MarsReconnaissance Orbiter have supported a broad range ofatmospheric airglow (127 μm O 145 and 29 μm OH) and aerosol(dust H O and CO ice) vertical profile retrievals Most recentlyCRISM limb observations over L =62-137deg in MY32 (Dec2013-May 2014) have obtained the first visible-to-near IRscattering spectra of CO ice clouds in the Mars equatorialmesosphere (ie 60-70 km altitudes 10S-10N over L =0-140degClancy et al 2007 Montemessin et al 2007) These spectra arehighly diagnostic of both the CO ice composition and cloudparitcle sizes (R =1-2 μm) The current report regards May 272014 (L =137deg) CRISM limb imaging observations of CO iceclouds centered near 10S75W at an altitude of 60 kmWhat is distinct about the May 2014 observation is the coincidenceof striking mesospheric O ( Δ ) 127 μm dayglow indicative ofvery low H Otemperature conditions which lead to locally intenseO enhancements (and 127 μm O emission associated with Ophotolysis) In this respect we have an unique temperatureindicator in the presence of CO ice clouds Interestingly LMDGCM photochemical simulations exhibit such localized O dayglowat the same locationseason associated with a thermal tidetemperature minimum (the current best explanation formesospheric CO ice cloud formation) We present CO cloudoptical depth and particle size determinations and discussobserved and modeled O mesospheric peak emissions in thecontext of very cold atmospheric temperatures implied by local COice formation and O emission

1

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Author(s) R T Clancy Michael Smith Franck Lefvegravere Brad Sandor Michael Wolff Tim McConnochie Kim Seelos Hari Nair Anthony Toigo Scott MurchieInstitution(s) 1 JHUAPL 2 LATMOS UPMC Univ Paris 3NASAGSFC 4 Space Science Inst 5 Univ Maryland

40108 ndash A Plume Tracing Source IdentifyingTechnique for Mars RoversWe have developed and field-tested a technique to identify andcharacterize the source of an effluent plume (biogenic orotherwise) on Mars using a slow-moving vehicle like a MarsRover The technique is based on terrestrial plume characterizationmethods (EPA Method 33a) and uses puff models of variablecomplexity to predict the plume behavior for a given source Thetechnique is developed assuming that a Mars Rover would beequipped with a high-performance eddy-sensing 3-D anemometer(eg a Martian Sonic Anemometer) as well as a fast-responsetracer molecule-specific sensor (eg a TLS methane sensor) Theplatform is assumed to move only once a day but have the abilityto observe throughout the day and night Data obtained from anyone sol while the effluent plume meanders across the rover can beused to estimate the azimuth range and strength of the source butcombining observations from multiple sols and locations is used toimprove the estimate of the souce location and strengthWe have conducted preliminary field tests using a SonicAnemometer (Gill and Campbell) and fast-response methanesensors (LICOR and Picarro) on mobile platforms using bothcontrolled and existing methane releases to prove our algorithm insimple terrain and with varying atmospheric stability We willdiscuss our results and the efficacy of our algorithm in real worldconditions

Author(s) Don Banfield Brian Lamb Chris Hovde TomFerraraInstitution(s) 1 Cornell Univ 2 GHD Inc 3 SouthwestSciences 4 Washington State University

40109 ndash Martian upper atmospheric aerosolproperties from Phobos eclipse observationSolar occultation photometry is a useful method for probing upperatmospheric aerosols using a long atmospheric path for directextinction measurements During April-June 2015 the MarsScience Laboratoryrsquos Mastcam was used for solar occultationphotometry by proxy 3 eclipse ingresses by Phobos into Marsrsquoshadow were observed as were 3 egresses from the shadow Theobservations occurred in late Southern summer at L 331-352degThe observations of the moonrsquos brightness sample the Martianatmosphere along the lines of site from the Sun to Phobos Theingresses and egresses sampled longitudes up to 1000s of km westor east of the roverrsquos position respectively sampled latitudes from30deg S to 7deg S over time and sampled local sunset or sunriserespectively Each eclipse was imaged with both Mastcam camerasM-100 with an RGB filter (638 551 and 493 nm) and M-34 withan 867-nm filter Light-curves for the eclipses were derived fromthe images and interpreted via a geometric model of the eventaccounting for the full range of lines of sight through theatmosphere The altitude of 50 extinction was found to varywithin the 40-60 km range Extinction varied with wavelengthfour events showed significantly higher extinction in the blue witha monotonic decrease with wavelength interpreted as a result of03-04 μm dust aerosols Two events (one of each type) showed nosignificant wavelength variation of extinction interpreted as aresult of large (gt1 μm) aerosols One of these probing local sunriseconditions may suggest a thin layer of CO ice cloud Future workmay allow retrieval of vertical gradients in aerosol size near themid-point of the sensitive region (ie altitudes near that of 50transmission andor path optical depth unity) andor identificationof discrete layers vs well-mixed aerosols (for instance clouds vsdust)

Author(s) Mark T LemmonInstitution(s) 1 Texas AandM University

402 ndash Asteroid Spins YORP and InteriorsThe Turning and Turning The CentreCannot Hold40201 ndash YORP Its originItrsquos all about photons and their behavior Yarkovsky (1844-1902)did not have the knowledge we have today about photons andradiation pressure Nevertheless he published a pamphlet in 1901that small rotating celestial bodies could absorb sunlight andreradiate it as heat after a delay resulting in possible orbitalchanges setting the stage for radiation effects in celestialmechanics Yarkovslyrsquos work remained obscure until Oumlpik recalledhaving read Yarkovskyrsquos pamphlet Oumlpik brought Yarkovskyrsquos ideato the attention of John A OrsquoKeefe in the late 1960s OrsquoKeefe thementor for two aspiring PhD students Paddack and Rubincamtold them about Yarkovsky In 1968 Paddack postulated that thereflection of sunlight off of small irregularly shaped celestialbodies could have a significant effect on their spin rates Hereferred to this as a windmill effect Paddack and OrsquoKeefe tested theidea of windmill shapes causing spin by dropping crushed stoneswith irregular shapes into a swimming pool and watching themtwirl Paddack then mimicked the space environment by placingwindmill-shaped artificial objects and tektites in a vacuum chamberon an almost frictionless bearing and spinning them up with astrong source of light conclusively showing the relation of shape tospin Earlier in 1954 Radzievskii wrote about the effects radiationpressure on variations in the albedo of small celestial bodies as ameans of changing their spin rates The uniform color of Paddackrsquostest bodies ruled out Radzievskiirsquos effect as the cause for theobserved spin-up The Yarkovsky effect was minimized because thetest object had a coating of vapor-deposited aluminum with a veryhigh albedo and consequently did not heat up In 2000 Rubincamapplied Paddackrsquos idea to small asteroids and called it the YORPeffect (YORP = Yarkovsky-OrsquoKeefe-Radzievskii-Paddack) to give ita catchy name and sell the idea In 2007 results were published inScience about the observed behavior of asteroid (54509) 2000 PH5stating that its spin rate changes because of the YORP effect(Lowery et al and Taylor et al) Since 2000 there have been morethan 400 papers and talks with ldquoYORPrdquo in the title or the abstract

Author(s) Stephen Paddack David P RubincamInstitution(s) 1 Goddard Space Flight Center 2 Self

40202 ndash Challenging the wall of fast rotatingasteroids ndash constraining internal cohesive strengthfor MBAs and NEAsWe report an observation of a 2 km size main belt asteroid (MBA)(60716) 2000 GD65 with a lightcurve indicating a rotation periodof 19529plusmn00002 hours ie challenging the lsquorubble pile spinbarrierrsquo This adds to a handful of MBAs recently observed by thePalomar Transient Factory (PTF) survey (Chang et al 2014 2015)with diameters between 05-15 km and lightcurves indicatingrotation periods of 12-19 hours These asteroids are relativelylarge compared to the population of small near-Earth asteroids(NEAs Dlt300 m) that can reach rotation periods as fast as 15797seconds as is the case of NEA 2014 RC (Moskovitz and MANOSteam)We apply the Holsapple (2007) model to these two distinctpopulations in order to constrain the cohesion within these objectsand to search for monolithic asteroids We use the lightcurversquosamplitude as indication of the triaxial shape ratio ab and assumebc=1 (ie agtb=c) While the density is a free parameter the givencohesion is the average of values for density ranges between 15 to25 gr cm^ which are measured density values for asteroids(Carry 2012)We find that the fast rotating MBAs must have internal cohesivestrength of at least ~25 to ~250 Pa in order to prevent disruptionagainst centrifugal acceleration Similar cohesion values have beenfound within lunar soils (100-1000 Pa Mitchell et al 1974)However since only a few MBAs rotate so quickly such internalcohesive strength might be rare within the population of km-sizeMBAs Among NEAs about 25 have minimal constrainedcohesion values similar to those found for the fast rotating MBAs

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Approximately 65 have no need for substantial cohesion valuesgt25 Pa Only ~10 of NEAs must have substantial internalcohesion of over 1000 Pa to prevent disruption however none ofthem are rotating fast enough to require a fully monolithic bodyie cohesion gt10 kPa

Author(s) David Polishook Nicholas Moskovitz Richard PBinzel Francesca E DeMeo Oded Aharonson CristinaThomas Matthew Lockhart Audrey Thirouin MichaelMommert David Trilling Brian BurtInstitution(s) 1 Lowell Observatory 2 MIT 3 NASA GoddardSpace Flight Center 4 Northern Arizona University 5 WeizmannInstitute of Science

40203 ndash Effects of Earth Encounters on theRotational Properties of Near-Earth ObjectsThe effects of Earth encounters on the physical properties ofnear-Earth objects (NEOs) have been shown to be significantfactors in their evolution Previous studies have examined theeffects of these encounters on reflectance spectra and effects suchas spin state and shape changes have been studied for specificasteroids and through simulation In this study archive data fromprevious NEO surveys were used to investigate rotationalfrequencies as a function of minimum orbit intersection distance(MOID) which we use as a proxy for Earth encounter likelihoodWhen comparing objects of similar sizes we find a highlysignificant difference in the dispersion of rotational frequency (p lt001 significant at a gt99 confidence level) between NEOpopulations that were likely to have had an Earth encounter andthose that are less likely to have had such an encounter Theencounternon-encounter distinction is found at a dividing MOIDvalue of 1 lunar distance (LD) These results were robust tochanges in the size of the moving average window as well as toremoval of the smallest objects from the encounter population andthe largest objects from the non-encounter population whichwould be most strongly affected by a known sizespin period biaswhere smaller objects tend to have shorter periods There was nostatistically significant difference in the mean rotation rates ofencounter and non-encounter objects however indicating thatencounters cause greater dispersion but do not preferentially spinobjects up or down at a detectable level Recent modeling work alsolends credibility to the idea that NEO interactions with theEarth-Moon system as a whole may be leading to the dispersiondifference boundary at 1 LD (Keane et al 2015 DPS)

Author(s) Ho Chit Siu James T Keane NicholasMoskovitz Richard P BinzelInstitution(s) 1 Lowell Observatory 2 Massachusetts Instituteof Technology 3 University of Arizona

40204 ndash Failure modes and conditions of ItokawaThe YORP effect has been found to play a crucial role in therotational evolution of small bodies Recent studies have arguedthat the YORP effect is very sensitive to the shape of an asteroid(Statler 2015 Icarus 202 502) and as the shape deforms canpossibly change (McMahon 2015 DDA meeting 30104) Suchsensitivity has been considered to affect the orbital evolution of anasteroid (Bottke et al 2015 Icarus 247 191) As a result thismysterious effect could make fast and slow rotators (personalcommunication with Bill Bottke 2015) In addition possiblecandidates of rotational disruption have also been discovered in thelast decades (eg Jewitt et al 2014 ApJ 784 L8) These studiesgave rise to the following question how does the shape of anasteroid change when subject to rotational variations from theYORP effect Better understandings of asteroid deformation andfailure at different spin periods will help us find clues of it To dothis we are surveying the failure modes and conditions of availableshape models with detailed mass information The main techniqueused is a plastic finite element model by Hirabayashi and Scheeres(2015 ApJ 798 L8) We have analyzed asteroid Itokawa which iscurrently spinning at a spin period of 121 hours Itokawarsquos failureconditions at different spin periods can be described by using theminimum cohesive strength that ensures stability of the structureThe results show that this minimum cohesive strength increases as

the spin period becomes shorter If the spin period is longer than45 hours a failure mode caused by a combination of compressionand tension occurs at cohesive strength less than 6 Pa At shorterspin periods however tension spreads out across the neck causingthe body to fail even at cohesive strength higher than it Since Hillrsquosstability condition is 52 hours once the body fails at spin periodsshorter than 45 hours it breaks into two components thateventually escape from one another In this presentation we willdiscuss the detailed failure modes and conditions of four differentshapes including Itokawa a top-like shape an elongated shape acontact binary and a strangely shaped asteroid

Author(s) Masatoshi Hirabayashi Daniel J ScheeresInstitution(s) 1 University of Colorado at Boulder

40205 ndash Asteroids With Tensile Strength The Case of2015 HM10Near-Earth asteroid 2015 HM10 was discovered on 2015 April 19with the 4-m Blanco Telescope at Cerro Tololo (MPEC 2015-H90)HM10 made a 000295 AU 114 lunar distance flyby of Earth onJuly 7 This was the asteroidrsquos closest approach to Earth until atleast 2419We observed HM10 with radar between July 5 and July 8 usingArecibo the 70 m DSS-14 and 34 m DSS-13 antennas at GoldstoneGreen Bank and elements of the Very Long Baseline Array(VLBA) Bistatic observations were crucial to obtainhigh-resolution images of HM10 due to the short round-trip traveltime of the radar signal which was as low as 295 s on July 7 Ourfinest image resolution was 375 mpixel in range obtained on July7 with the new 80 kW C-band (7190 MHz 42 cm) transmitter onDSS-13 and receiving at Green Bank with the new radar backendOptical lightcurves obtained prior to closest approach indicated thatHM10 has a spin period of ~222 minutes and an elongated shape(W Ryan pers comm) The delay-Doppler radar images confirmthe rotation period estimated from photometry and reveal thatHM10 has a long-axis extent of 80-100 m with an equatorial aspectratio of about 21 Radar speckle tracking transmitting from Areciboand receiving with the VLBA on July 6 rule out any non-principalaxis lsquowobblersquo with an amplitude greater than ~10ordmHM10rsquos rapid rotation implies significant cohesion with aminimum tensile strength of 25-150 Pa required at its center toprevent disruption assuming overall bulk density between 07 and39 g cm This is comparable to strength predictions forrubble-pile aggregates (eg Scheeres Britt Carry amp Holsapple2015 Asteroids IV in press) HM10 is not necessarily a lsquomonolithrsquoHM10rsquos shape is complex and irregular The radar images showangular features and lsquofacetsrsquo up to ~30 m across There is also acluster of radar-bright pixels that tracks with HM10rsquos rotationconsistent with a high standing feature 15-20 m across Thisfeature is similar in appearance to radar images of decameter-scaleboulders on other asteroids

Author(s) Michael W Busch Lance AM Benner Shantanu P Naidu Marina Brozovic James E Richardson Edgard G Rivera-Valentin Patrick A Taylor H Alyson Ford Frank D Ghigo Jon D Giorgini Joseph S Jao LawrenceTeitelbaumInstitution(s) 1 Arecibo Observatory 2 Jet PropulsionLaboratory California Institute of Technology 3 National RadioAstronomy Observatory 4 SETI Institute

40206 ndash Size estimate of (99942) Apophis based onradar imaging(99942) Apophis is one of the most important near-Earth asteroidsever discovered It will make a very close Earth approach on FridayApril 13 2029 when it will pass within only a few Earth radii aboveEarths surface This will be the closest approach by something thislarge currently known Apophis approached within 01 au inJanuary of 2013 and we organized an extensive radar campaign atGoldstone and Arecibo between December 2012 and March 2013Our primary objective was to obtain ranging measurements toimprove the orbit characterize its physical properties and facilitatedetection of the Yarkovsky effect leading to estimation of the massand bulk density We obtained frequency-only data and 150 m and

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75 m ranging data The signal-to-noise ratios (SNRs) were strongenough so that coarsely resolved delay-Doppler images revealedaspects of Apophisrsquo shape The visible extents varied from ~02 kmto ~04 km and the bandwidths varied from 09 Hz to14 Hz Theobject is clearly elongated which is consistent with the largelightcurve amplitude of ~09 mag reported by Behrend et al (httpobswwwunigech~behrendr099942apng) and Pravec etal (Icarus 233 48-60 2014) The radar images suggest thatApophis could be a contact binaryPravec et al have estimated the shape and spin of Apophis fromlightcurves that were collected at similar times as our radar dataThe radar data were not strong enough for 3D shape modeling butwe used the Shape software (Hudson Remote Sens Rev 8195-203 1993 and Magri et al Icarus 186 152-177 2007) to scalethe convex lightcurve-derived shape model to fit the radar data Wefind that the best χ value corresponds to the model that has043times030times026 (plusmn004 plusmn003 plusmn003) km for long intermediateand short axis and a dynamically equivalent equal volumeellipsoid of 031plusmn003 km

Author(s) Marina Brozovic Lance Benner JosephMcMichael Petr Pravec Petr Scheirich Jon Giorgini ChrisMagri Michael Busch Joseph Jao Clement Lee MichaelNolan Patrick Taylor Ellen Howell Martin SladeInstitution(s) 1 Arecibo Observatory 2 Astronomical InstituteAcademy of Sciences of the Czech Republic 3 Jet PropulsionLaboratoryCaltech 4 SETI Institute 5 University of Arizona 6University of Maine

40207 ndash Orbital and Physical Characteristics ofMeter-sized Earth ImpactorsWe have analysed the orbits and ablation characteristics in theatmosphere of more than 60 earth-impacting meteoroids of onemeter in diameter or larger Using heights at peak luminosity as aproxy for strength we find that there is roughly an order ofmagnitude spread in the apparent strength of the population ofmeter-sized impactors at the Earth The orbits and physicalstrength of these objects are consistent with the majority beingasteroidal bodies originating from the inner main asteroid belt Wefind ~10-15 of our objects have a probable cometary (Jupiter-Family comet andor Halley-type comet) origin based on orbitalcharacteristics alone Only half this number however showevidence for the expected weaker than average structure comparedto asteroidal bodies Almost all impactors show peak brightnessbetween 20-40 km altitude Several events have exceptionally high(relative to the remainder of the population) heights of peakbrightness These are physically most consistent with highmicroporosity objects though all were on asteroidal-type orbitsWe also find three events including the Oct 8 2009 airburst nearSulawesi Indonesia which display comparatively low heights ofpeak brightness consistent with strong monolithic stones or ironmeteoroids Based on orbital similarity we find a probableconnection among several NEOs in our population with the Tauridmeteoroid complex No other major meteoroid streams showlinkages with the pre-atmospheric orbits of our meter-classimpactors Our events cover almost four orders of magnitude inmass but no trend in height of peak brightness is evidentsuggesting no strong trend in strength with size for small NEOs afinding consistent with the results of Popova et al (2011)

Author(s) Peter G Brown Paul Wiegert David Clark Edward TagliaferriInstitution(s) 1 ET Space Systems 2 Univ of Western Ontario

40208 ndash Patterns of Failure in HeterogeneousSelf-gravitating AggregatesDuring the last 15 years or so the Planetary Sciences communityhas been using DEM simulation codes to study small granularNEOs In general these codes treat gravitational aggregates asconglomerates of spherical particles Lately Finite ElementMethod (FEM) codes and theoretical tools (Limit analysis)commonly used to study soil mechanics have also been employedto analyze the failure conditions and disruption patterns ofgranular asteroids as well as idealized simulation constructs One

general assumption has been that these granular systems havehomogeneous interiors In this research we change this and studythe effect of stronger and weaker interiors in their disruptionpatterns and failure mechanismsTheory and simulations have shown that homogeneous aggregatesspun at disruption rates fail initially at the centre and so it isinteresting to explore the influence of a stronger or weaker core intheir disruption mechanisms In our research we explore thefailure mechanics of spherical aggregates with an angle of frictionof 35˚ and systematically change the tensile strength and size of aspherical concentric core These aggregates are slowly spun up todisruption spin rates so that we can observe and analyze theirdisruption mechanics through our DEM code At the same time weuse Limit analysis to provide the upper and lower bounds to findthe actual conditions for failureWhat we observe is that simulations and theory point to surfaceshedding as the prevalent mechanism for aggregates with strongercores Also a core of appropriate size produces a shape profilesimilar to 1999 KW4 alpha Initial simulations of aggregates withweak cores continue to fail first a the centre but if in homogeneousaggregates there was a smooth (cohesion dependent) change fromshedding to fission here this does not happen When the size ofthe core is gt05R where R is the radius of the original bodymaterial is shed from a now oblate body For a core with a radius of05R on the other hand we observe that the break-up of the coreleads to a severe fracturing but not to fission These and otherscenarios will be explored in greater detail during the conference

Author(s) Paul Saacutenchez Daniel Scheeres MasatoshiHirabayashiInstitution(s) 1 University of Colorado at Boulder

40209 ndash Geodynamic stability of the primary in thebinary asteroid system 65803 DidymosThe moon of the near-Earth binary asteroid 65803 Didymos is thetarget of the Asteroid Impact and Deflection Assessment (AIDA)mission This mission is a joint concept between NASA and ESA toinvestigate the effectiveness of a kinetic impactor in deflecting anasteroid The mission is composed of two components theNASA-led Double Asteroid Redirect Test (DART) that will impactthe Didymos moon and the ESA-led Asteroid Impact Monitoring(AIM) mission that will characterize the Didymos system In orderto provide AIDA constraints on the physical character of the bothobjects in this binary system we undertook preliminary numericalinvestigations to evaluate the stability of the shape of the primaryusing its rapid 226 h rotation We modeled the primary as a rubblepile Each model consisted of thousands of uniform rigid spherescollapsed together under their own gravity to form a spherical pilethat was then carved to match the current radar-derived shapemodel of the primary as well as other comparable shapes (egasteroid 1999 KW4 spheres) that were scaled to match bestestimates of the size of Didymos Each model was given a startingrotation period of 6 h with the spin axis aligned to the pole At eachtimestep the spin rate was increased by a small amount so that afterabout 1 million timesteps the spin would match the observedrotation of 226 h We tested a range of bulk densities spanning thecurrent observational uncertainty (mean 24 gcc) usinggravel-like material parameters that provide significant resistanceto sliding and rolling We find that at the upper range of the densityuncertainty it is possible for Didymos to hold its shape and not losemass at its nominal rotation period without the need for cohesiveforces At lower densities or with smoother particles significantshape change occurs and mass loss is possible We conclude thatbased on the radar shape available at the time of this writingDidymos is marginally stable as a rubble pile with bulk densityclose to 3 gcc Revisions to the radar shape in process may allowfor stability at lower bulk densities without cohesion These resultssuggest that the moon of Didymos may also not be heavilyinfluenced by cohesion

Author(s) Olivier S Barnouin Clara Maurel Derek CRichardson Ronald-Louis Ballouz Stephen Schwartz PatrickMichelInstitution(s) 1 ISAE-Supaero 2 JHUAPL 3 Lagrange LabUCA Cocircte drsquoAzur Observatory CNRS 4 Univ of Maryland

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403 ndash Jovian Planet Interiors DeepAtmosphere and Structure40301 ndash Gravity and Zonal Flows of Giant PlanetsFrom the Euler Equation to the Thermal WindEquationThe nature of the east-west zonal flows observed on the cloud levelof the solar system giant planets remains to be determined Theupcoming gravity and magnetic field measurements to be carriedout by the Juno mission and the Cassini Grand Finale provide anopportunity to establish an observational fact about whether theseflows are shallow atmospheric dynamics or surface expression ofdeep interior dynamics It is currently debated whether the thermalwind equation (TWE) is applicable in forward calculating thegravity field associated with deep zonal flows Here we will presenta critical comparison between the Euler equation and the thermalwind equation (TWE) The TWE which is a local diagnosticrelation captures the local density variations associated with thezonal flows while neglects the global shape change and densityvariations with non-local origins Our analysis shows that theglobal corrections to the high degree gravity moments are small(less than a few tens of percent) Our analysis also shows that theapplicability of the TWE in calculating the gravity moments doesdepend crucially on retaining the non-sphericity of the backgrounddensity and gravity Only when the background non-sphericity ofthe planet is taken into account the TWE makes accurate enoughprediction (with a few tens of percent errors) for the high-degreegravity moments associated with deep zonal flows

Author(s) Hao Cao David J StevensonInstitution(s) 1 Caltech

40302 ndash The gravity signature of atmosphericdynamics on giant planets comparing the potential-theory and thermal-wind approachesThe upcoming Juno and Cassini gravity experiments of Jupiter andSaturn respectively will allow us to probe the internal dynamics ofthese planets through accurate analysis of their gravity spectra Todate two general approaches have been suggested for relating theflow velocities and gravity fields In the first potential-theory isinvoked to calculate the gravity field due to internal dynamics in anoblate spheroid planet with full differential rotation The secondapproach calculated in the reference frame of the rotating planetassumes that due to the large scale and rapid rotation of theseplanets the winds are to leading order in geostrophic balance andtherefore thermal wind balance relates the wind shear to thedensity gradients The first method allows accurate calculations ofthe gravity harmonics but can take into account only the case offull differential rotation (completely barotropic flow) while thesecond method can take into account any internal flow structurebut is limited to only calculating the dynamical contribution and tospherical symmetry This study comes to relate the two methodsboth from a theoretical perspective showing that they areanalytically identical in the barotropic limit and numericallythrough systematically comparing the model solutions of thegravity harmonics We find that despite the sphericity assumptionthe thermal wind solutions match well the potential-theorysolutions

Author(s) Joseph E Davighi Yohai Kaspi Eli Galanti William B HubbardInstitution(s) 1 University of Arizona 2 University ofCambridge 3 Weizmann Institute of Science

40303 ndash Tides in Giant PlanetsThe arrival of Juno at Jupiter in less than a year necessitatesanalysis of what we can learn from the gravitational signal due totides raised on the planet by satellites (especially Io but alsoEuropa) In the existing literature there is extensive work on statictidal theory (the response of the planet to a tidal potential whosetime dependence is ignored) and this is what is usually quotedwhen people refer to tidal Love numbers If this were correct thenthere would be almost no new information content in the

measurement of tidally induced gravity field since the perturbationis of the same kind as the response to rotation (ie themeasurement of J a well-known quantity) However tides aredynamic (that is k is frequency dependent) and so there is newinformation in the frequency dependent part There is also (highlyimportant) information in the imaginary part (more commonlyexpressed as tidal Q) but there is no prospect of direct detection ofthis by Juno since that quadrature signal is so small The differencebetween what we expect to measure and what we can alreadycalculate directly from J is easily shown to be of order the squareof tidal frequency over the lowest order normal mode frequencyand thus of order 10 However the governing equations are notsimple (not separable) because of the Coriolis force Anapproximate solution has been obtained for the n =1 polytropeshowing that the correction to k is even smaller typically a fewpercent because the tidal frequency is not very different from twicethe rotation frequency Moreover it is not highly sensitive tostructure in standard models However the deep interior of theplanet may be stably stratified because of a compositional gradientand this modifies the tidal flow amplitude changing the dynamick but not the static k This raises the exciting possibility that wecan use the determination of k to set bounds on the extent ofstatic stability if any There is also the slight possibility that thetidal frequency is coincidentally close to some resonance as wouldbe required if (as some have suggested) the tidal Q is currentlysmall (eg a few thousand or less) Predictions and detectability forJuno will be presented

Author(s) David J StevensonInstitution(s) 1 Caltech

40304 ndash Laboratory Measurements of the 5-20 cmWavelength Opacity of Ammonia and Water Vaporunder High-Temperature Conditions charactyeristicof the Deep Jovian AtmosphereIn the past decade several extensive laboratory studies have beenconducted of the microwave opacity of ammonia and water vapor inpreparation for interpretation of the precise measurements ofJovian microwave emission to be made with the Juno MicrowaveRadiometer (MWR) instrument (See eg Hanley et al (Icarus202 2009) Karpowicz and Steffes (Icarus 212 2011) Karpowiczand Steffes (Icarus 214 2011) and Devaraj et al (Icarus 2412014)) All of these works include models for the opacity of theseconstituents valid over the pressure and temperature rangesmeasured in their laboratory experiments (temperatures up to 500K and pressures up to 100 bars) However studies of the Jovianmicrowave emission indicate that significant contributions to theemission at the 24-cm and 50-cm wavelengths to be measured bythe Juno MWR will be made by layers of the atmosphere withtemperatures at or exceeding 600 K While the ammonia opacitymodels described by Hanley et al (Icarus 202 2009) and Devarajet al (Icarus 241 2014) give consistent results at temperatures upto 500 K (within 6) they diverge significantly at temperaturesand pressures exceeding 550 K and 50 bars respectively Similarlyat temperatures above 600 K the model for water vapor opacitydeveloped by Karpowicz and Steffes (Icarus 212 2011 Icarus 2142011) exhibits larger than expected microwave opacity To resolvethese ambiguities we present results of laboratory measurementsof the microwave opacity of ammonia in a hydrogenheliumatmosphere at temperatures up to 600 K and pressures up to 80Bars and that for water vapor at temperatures up to 600 K

This work was supported by the NASA Juno Mission

Author(s) Amadeo Bellotti Paul G SteffesInstitution(s) 1 Georgia Institute of Technology

40305 ndash The depths of clouds on JupiterObservational constraints on the OH ratioThe oxygen abundance in Jupiter is an important constraint onplanet formation and conditions in protoplanetary disks Oxygenin the form of water is also dynamically significant in Jupitersatmosphere as a tracer of circulation and as a carrier of latent heatWe have developed a technique to spectroscopically measure the

1 1

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22

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depth of opaque cloud tops in Jupiters atmosphere (Bjoraker et al2015 ApJ in press arXiv150804795) We measure resolvedCH D line shapes in the 5-micron window of Jupiters spectrum todistinguish between cloud-top pressure levels of about 3 to 10 barsWe will use the retrieved cloud top pressure levels to place lowerlimits on the deep OH ratio in Jupiter based on KeckNIRSPECspectra acquired in January 2013 Since our spectra do not directlygive the temperaturepressure profile in the cloud layerconstraining the OH ratio requires independent atmosphericstructure data We will review observational and theoreticalconstraints on Jupiters thermal structure which lead touncertainty bounds on the OH ratio we derive Preliminary workto date suggests that our technique may be able to determinewhether or not the Galileo Probe Mass Spectrometer OHmeasurement can be representative of the planets bulkabundance and whether O is supersolar in Jupiter like the othervolatile elements C N and S If we can distinguish between OHlower limits of 10x and 3x solar we will be able to test thehypothesis that Jupiters volatiles must have been delivered viawater ice clathrates[This conference abstract is supported by NASA grantNNX11AM55G issued through the Outer Planets ResearchProgram and by grants NNX14AJ43G and NNX15AJ41G throughthe Planetary Astronomy and Solar System ObservationsPrograms]

Author(s) Michael H Wong Gordon L Bjoraker Imke dePater Maacuteteacute AacutedaacutemkovicsInstitution(s) 1 NASA Goddard Space Flight Center 2University of California

40306 ndash Variation in the Deep Gas Composition inHot Spots on JupiterWe used CSHELL on NASArsquos Infrared Telescope Facility andNIRSPEC on the Keck telescope in the last two years to spectrallyresolve line profiles of CH D NH PH and H O in 5-micronHot Spots on Jupiter The profile of the CH D lines at 466 micronsis very broad in both NEB and SEB Hot Spots due to collisions withup to 8 bars of H where unit optical depth occurs due to collision-induced H opacity The extreme width of these CH D featuresimplies that the Hot Spots that we observed do not have significantcloud opacity for P gt 2 bars We retrieved NH PH and gaseousH O within Hot Spots in both the NEB and SEB We had dry nightson Mauna Kea and a sufficient Doppler shift to detect H O We willcompare line wings to derive H O profiles in the 2 to 6-bar regionNEB Hot Spots are depleted in NH with respect to adjacentregions Interestingly SEB Hot Spots exhibit stronger NHabsorption than NEB Hot Spots In addition SEB Hot Spots havevery similar 5-micron spectra as neighboring longitudes in the SEBimplying similar deep gas composition The dynamical origin ofSEB Hot Spots is much less studied than that of NEB Hot Spots soour observations of gas composition in both regions may constrainmechanisms for forming Hot Spots

Author(s) Gordon Bjoraker Imke de Pater Michael HWong Mate Adamkovics Tilak Hewagama Brigette HesmanInstitution(s) 1 NASAs GSFC 2 Univ of California-Berkeley3 Univ of Maryland

40307 ndash Coupled Gas Giant Atmospheres SolarHeating vs Interior HeatingThe weather layers of Jupiter and Saturn receive both solarradiation and heat from the deep interior Currently numericalmodels fall into two broad categories deep convecting interiorsthat lack an outer solar-heated troposphere or thin shells thatrepresent only a troposphere with parameterized heating from thelower boundary Here we present results from a new coupledcirculation model that allows deep convective plumes andcolumnar structures to interact with a stable troposphere that isheated by the sun Equatorial superrotation observed on Jupiterand Saturn extends in axially-aligned columns from the deepinterior through the troposphere A tropospheric midlatitudebaroclinic zone due to solar heating competes with the outer edgesof the deep rotating columns to characterize midlatitude jet and

temperature structure We demonstrate this interplay betweensolar heating and interior heating in setting the strength and depthof the jets for a range of idealized gas giants The relative impact ofeach is modulated by the static stability of the troposphere whichacts as a proxy for water abundance We also show the impact ofaxial tilt with respect to solar radiation on asymmetries betweenthe Northern and Southern hemispheres

Author(s) Morgan E ONeill Yohai Kaspi Eli GalantiInstitution(s) 1 Weizmann Institute of Science

40308 ndash Deciphering Jupiters complex flowdynamics using the upcoming Juno gravitymeasurements and an adjoint based dynamical modelThe nature of the large scale flow on Jupiter below the cloud level isstill unknown The observed surface wind might be confined to theupper layers or be a manifestation of deep cylindrical flowMoreover it is possible that in the case where the observed wind issuperficial there exists deep flow that is completely separated fromthe surface To date all models linking the wind (via the induceddensity nomalies) to the gravity field to be measured by Junoconsider only wind flow related to the observed could level windSome assume full cylindrical flow while others allow for the wind todecay with depthHere we explore the possibility of complex wind dynamics thatinclude both the upper-layer wind and a deep flow that iscompletely detached from the flow above it The surface flow isbased on the observed cloud level flow and is set to decay withdepth The deep flow is constructed synthetically to producecylindrical structures with variable width and magnitude thusallowing for a wide range of possible setups of the unknown deepflow This flow is also set to decay when approaching the surfaceflow in coordination with the exponential decay rate The combined3D flow is then related to the density anomalies via a dynamicalmodel taking into account oblateness effects as well and theresulting density field is then used to calculate the gravitationalmoments An adjoint inverse model is constructed for thedynamical model thus allowing backward integration of thedynamical model from the expected observations of the gravitymoments to the parameters controlling the setup of the deep andsurface flows We show that the model can be used for examinationof various scenarios including cases in which the deep flow isdominating over the surface wind The novelty of our adjoint basedinversion approach is in the ability to identify complex dynamicsincluding deep cylindrical flows that have no manifestation in theobserved cloud-level wind Furthermore the flexibility of theadjoint method allows for a wide range of dynamical setups so thatwhen new observations and physical understanding will arisethese constraints could be easily implemented and used to betterdecipher Jupiter flow dynamics

Author(s) Eli Galanti Yohai KaspiInstitution(s) 1 Weizmann Institute of Science

40309 ndash Jupiterrsquos tropospheric composition andcloud structure from high-resolution ground-basedspectroscopyThe CRIRES instrument on the Very Large Telescope was used tomake high-resolution (R=100000) observations of Jupiter in the45-52 μm spectral range At these wavelengths Jupiterrsquosatmosphere is optically thin and the spectra are sensitive to the 4-8bar region This enabled us to spectrally resolve the line shapes offour minor species in Jupiterrsquos troposphere CH D GeH AsHand PH The slit was aligned north-south along Jupiterrsquos centralmeridian allowing us to search for latitudinal variability in theseline shapes The spectra were analysed using the NEMESISradiative transfer code and retrieval algorithmThe CH D line shape is narrower in the cool zones than in thewarm belts CH D is chemically stable and does not condense inJupiterrsquos atmosphere so this difference cannot be due to variationsin the CH D abundance Instead it can be modelled as variationsin the opacity of a deep cloud located at around 4 bar This deepcloud is opaque in the zones and transparent in the beltsWe also observe variability in the GeH line shape with stronger

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absorption features in the belts than in the zones As adisequilibrium species GeH is expected to vary with latitude butwe found that the variations in the line shape could be entirelyexplained by the variations in the cloud structureIn contrast there is clear evidence for spatial variability in theremaining two molecular species AsH and PH Their absorptionfeatures are weak near the equator and significantly stronger athigh latitudes A full latitudinal retrieval leads to a broadlysymmetric profile for both species with a minimum at the equatorand an enhancement towards the poles

Author(s) Rohini Sara Giles Leigh N Fletcher Patrick GJ IrwinInstitution(s) 1 Leicester University 2 Oxford University

404 ndash Extrasolar Planets Terrestrial andNeptunian Planets40401 ndash Cassini VIMS Spectra of the Earth fromSaturn Orbit an Extrasolar Planet AnalogCassini VIMS has obtained spectra of the Earth while in Saturnorbit making observations of the Saturn system when the sun wasbehind Saturn The observations made in September 15 2006 andJuly 19 2013 are visible-near-infrared spectra (035 - 51 microns)of the Earth obtained at the furthest distance from the sun to dateThe Earth was sub-pixel 00088 milliradian in 2013 and 00085milliradian in 2006 and the signal-to-noise ratio is low A VIMSpixel IFOV is 025 x 05milliradian As such these data are likely representative of the firstspectra that might be obtained of extrasolar terrestrial-like planetsWhat information can be derived from such remote observationsThe observation made in 2013 had a phase angle of 97 degrees withmultipleimage cubes providing a higher SN average The 2006 observationwas made at a phase angle of 33 degrees but is a single cube 1 pixelThe 2006 observation has Africa dominant on the disk while the2013 observation is mostly ocean with part of South America insunlight The 2013 visible data show clear signatures of Rayleighscattering but this blue coloring can be from both the atmosphereandor ocean The 2006 data show a flatter spectrum a signatureof land Both observations include the Moon in the field of viewThe 035-25 micron spectral range shows significant absorptiondue to H2O liquid + gas The thermal signature is very strong withthe highest SN of the entire spectrum The best fit preliminarytemperatures are 280 K with a small 380 K component (from theMoon) putting at least some of the planet in the goldilocks zoneThere is strong absorption by CO2 at 425 microns in both 2013and 2006 data There is possible detection of chlorophyll andoxygen emission but higher SN would be required for a positivedetection The spectral profile of the thermal emission could beused to constrain the diameter of the planet If such spectra wereobtained of an extrasolar planet we could conclude that the planethad large regions of liquid water and exposed land at temperaturesexcellent for life in a habitable zone If the chlorophyll signaturecould be confirmed it would be a positive identification of life froma remote distance

Author(s) Roger Nelson Clark Matthew M Hedman Robert H Brown Gianrico Filacchione Philip D Nicholson Jason W BarnesInstitution(s) 1 Cornel U 2 INAF 3 Planetary ScienceInstitute 4 U Arizona 5 U Idaho

40402 ndash Under an Orange Sky The ManyImplications of Organic Haze for Earthlike PlanetsGeochemical evidence suggests Archean Earth was intermittentlyenshrouded in an organic haze resulting from methane photolysisHazy exoplanets may be common and hazes can significantlyimpact the environment of habitable planets Earth is frequentlystudied as an analog for habitable exoplanets and Archean Earth isthe most alien planet we have geochemical data for We have used1D photochemical-climate and radiative transfer simulations toexamine the climate surface radiation environment and spectra of

Archean Earth with fractal hydrocarbon haze We find that hazewould have strongly impacted Earthrsquos climate lowering theplanetary surface temperature by 20-30 K However this coolingcan be countered by concentrations of greenhouses gasesconsistent with geochemical constraints For example anatmosphere with 2 CO 037 CH and a self-consistenthydrocarbon haze has a globally averaged surface temperature of274 K which GCM models have shown is consistent with a largeopen ocean fraction (Charnay et al 2013) The cooling from hazemeans that there exists a ldquohazy habitable zonerdquo closer to the starthan the traditional habitable zone boundaries Our results suggestthat the hazy habitable zone can extend to the distance of VenusAn organic haze produces strong remotely detectable spectralfeatures especially at wavelengths lt 05 μm reddening theplanetrsquos color The strong absorption of UV radiation by this hazemeans it could have provided a UV shield for the Archean Earthprior to the rise of oxygen when there was no ozone layer we showthat an organic haze can block 97 of the surface-incident UVC (λlt 028 μm) radiation compared to a haze-free planet UVCradiation directly dissociates DNA and it is blocked by ozone in themodern atmosphere Organic hazes may therefore benefit surfacebiospheres on Earth and similar exoplanets Finally assuminggeochemical constraints on the Archean atmospheric compositionwe show that abiotic levels of methane flux to the atmosphere areinsufficient to form an organic haze For Earthlike exoplanetsorganic haze may therefore be a novel type of spectral biosignature

Author(s) Giada Arney Shawn D Domagal-Goldman Victoria S Meadows Eric Wolf Edward W Schwieterman Benjamin Charnay Mark Claire Eric HebrardInstitution(s) 1 NASA Goddard Space Flight Center 2University of Colorado 3 University of St Andrews 4 Universityof Washington

40403 ndash CO Effects on Habitability of StellarExoplanet SystemsWe assess how differences in the composition of exoplanet hoststars might affect the availability of water in their systemsparticularly the role of carbon and oxygen abundances Water oneof the key chemical ingredients for habitability may be in shortsupply in carbon-rich oxygen-poor systems even if planets exist inthe lsquohabitable zonersquo For the solar system CO = 055 is particularlyimportant in determining the refractory (silicate and metal) tovolatile ice ratio expected in material condensed beyond the snowline (Gaidos E J Icarus 145 637 2000 Wong M H et al inOxygen in the Solar System GJ MacPherson Ed 2008) Ouranalysis of published compositions for a set of exoplanet host stars(Johnson T V et al ApJ 757(2) 192 2012) showed that theamount of condensed water ice in those systems might range fromas much as 50 by mass for sub-solar CO = 035 to less than a fewpercent for super-solar CO = 07 A recent analysis using similartechniques (Pekmezci G S Dottorato di Ricerca in AstronomiaUniversitagrave Degli Studi di Roma ldquoTor Vergatardquo 2014) of a muchlarger stellar composition data set for 974 FGK stars (Petigura Eand Marcy G Journal of Astrophysics 735 2011) allows us toassess the possible range of water ice abundance in thecircumstellar accretion disks of these lsquosolar-typersquo stars (of which 72were known to have one or more planets as of 2011) Stellar CO ina subset (457 stars) of this stellar database with reported C O Niand Fe abundances ranges from 03 to 14 The resulting computedwater ice fractions and refractory (silicate + metal) fractions rangefrom ~0 to 06 and 03 to 09 respectively These results haveimplications for assessing the habitability of exoplanets since theyconstrain the amount of water available beyond the snow line fordynamical delivery to inner planets depending on the host starsrsquoCO in the circumstellar nebula TVJ acknowledges governmentsupport at JPLCaltech under a contract with NASA JIL wassupported by the JWST Project through NASA OM acknowledgessupport from CNES

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Author(s) Torrence V Johnson Guumll Sevin Peckmezci Olivier Mousis Jonathan I Lunine Nikku MadhusudhanInstitution(s) 1 Aix Marseille Universiteacute CNRS LAM(Laboratoire dAstrophysique de Marseille) 2 Center forRadiophysics and Space Research 3 Institute of AstronomyUniversity of Cambridge 4 Jet Propulsion Laboratory 5Universitagrave Degli Studi di Roma ldquoTor Vergatardquo

40404 ndash Spectral identification of abiotic O buildupfrom early runaways and rarefied atmospheresThe spectral detection of oxygen (O ) in a planetary atmospherehas been considered a robust signature of life because O is highlyreactive on planets with Earth-like redox buffers and becausesignificant continuous abiotic sources were thought to beimplausible However recent work has revealed the possibility thatsignificant O may build-up in terrestrial planet atmospheresthrough (1) photochemical channels or (2) through massivehydrogen escape We focus on the latter category here Significantamounts of abiotic O could remain in the atmospheres of planetsin the habitable zones of late type stars where an early runawaygreenhouse and massive hydrogen escape during the pre-main-sequence phase could have irreversibly oxidized the crust andmantle (Luger amp Barnes 2015) Additionally it has beenhypothesized that O could accumulate in the atmospheres ofplanets with sufficiently low abundances of noncondensable gasessuch as N where water would not be cold trapped in thetroposphere leading to H-escape from UV photolysis in a wetstratosphere (Wordsworth amp Pierrehumbert 2014) Weself-consistently model the climate photochemistry and spectra ofboth rarefied and post-runaway high-O atmospheres Because anearly runaway might not have lasted long enough for the entirewater inventory to have escaped we explore both completelydesiccated scenarios and cases where a surface ocean remains Wefind ldquohabitablerdquo surface conditions for a wide variety of oxygenabundances atmospheric masses and CO mixing ratios If Obuilds up from H escape the O abundance should be very highand could be spectrally indicated by the presence of Ocollisionally-induced absorption (CIA) features We generatesynthetic direct-imaging and transit transmission spectra of theseatmospheres and calculate the strength of the UVVisible and NIRO CIA features We find that while both the UVVisible and NIRO CIA features are strong in the direct-imaging spectra of veryhigh-O atmospheres only the NIR O CIA features are significantin transmission spectra We also conclude that detection of N -NCIA in transmission or direct-imaging spectra could rule out Oorigination from H-escape from thin atmospheres

Author(s) Edward Schwieterman Victoria Meadows Shawn Domagal-Goldman Giada Arney Rodrigo Luger RoryBarnesInstitution(s) 1 NASA Goddard Space Flight Center 2University of Washington

40405 ndash Exoplanet Magma Ocean Magnetic Fieldsmay be CommonKepler data suggest that many exoplanets have low densities fortheir mass and therefore probably have hydrogen-richatmospheres For all but very thin atmospheres these have aconvective zone beneath the radiative outer region and as aconsequence have high temperatures at the assumed silicatesurface usually above the liquidus implying a magma ocean Inmany cases the resulting high internal temperatures are sufficientto allow for dynamo action in the magma There the electricalconductivities are high enough to support such a dynamo but notso high that the thermal conductivity favors conduction overconvection High conductivity is bad for a dynamo so this lowerthermal conductivity makes such magma ocean dynamospreferable to a putative iron core dynamoIn our simple models the atmospheres of exoplanets will contain aconvective zone beneath a radiative zone if sufficiently thick Wedevelop a simple model for the surface temperature of a rockyexoplanet with atmosphere-to-planet mass ratios 0001 to 10planet masses 1-10 Moplus and effective temperatures 150-1000 K Inmost models with atmosphere mass ratios greater than 01 the

rocky surface is above 1500 K above the liquidus for silicatemagma Assuming a fully molten silicate magma ocean planet ofEarthlike composition the primary mode of heat transport isconvection except at the high-temperature high atmosphere massratio end From that even with conservative estimates of theelectrical conductivity of the liquid silicate magma the nominalmagnetic Reynolds number at the surface seldom falls below 10Thus the tentative conclusion is that rocky exoplanets withsufficiently thick atmospheric envelopes to melt the surface cangenerate magnetic fields irrespective of their putative coresEstimates of the magnetic field were done following Christensenyielding surface values in the range of 01 to 05 Gauss

Author(s) Alexander Bourzutschky David StevensonInstitution(s) 1 California Instiute of Technology

40406 ndash Understanding the Early Evolution of Mdwarf Extreme Ultraviolet RadiationThe chemistry and evolution of planetary atmospheres depends onthe evolution of high-energy radiation emitted by its host starHigh levels of extreme ultraviolet (EUV) radiation can drasticallyalter the atmospheres of terrestrial planets through ionizingheating expanding chemically modifying and eroding them duringthe first few billion years of a planetary lifetime While there isevidence that stars emit their highest levels of far and nearultraviolet (FUV NUV) radiation in the earliest stages of theirevolution we are currently unable to directly measure the EUVradiation Most previous stellar atmosphere models under-predictFUV and EUV emission from M dwarfs here we present newmodels for M stars that include prescriptions for the hot lowestdensity atmospheric layers (chromosphere transition region andcorona) from which this radiation is emitted By comparing ourmodel spectra to GALEX near and far ultraviolet fluxes we are ableto predict the evolution of EUV radiation for M dwarfs from 10 Myrto a few Gyr This research is the next major step in the HAZMAT(HAbitable Zones and M dwarf Activity across Time) project toanalyze how the habitable zone evolves with the evolvingproperties of stellar and planetary atmospheres

Author(s) Sarah Peacock Travis Barman EvgenyaShkolnikInstitution(s) 1 Arizona State University 2 University ofArizona LPL

40407 ndash A Statistical Characterization of Reflectionand Refraction in the Atmospheres of sub-SaturnKepler Planet CandidatesWe present the results of our method to detect small atmosphericsignals in Keplerrsquos close-in sub-Saturn planet candidate lightcurves We detect an average secondary eclipse for groups of super-Earth Neptune-like and other sub-Saturn-sized candidates byscaling and combining photometric data of the groups ofcandidates such that the eclipses add constructively This greatlyincreases the signal-to-noise compared to combining eclipses forindividual planets We have modified our method for averagingshort cadence light curves of multiple planet candidates (2014 ApJ794 133) and have applied it to long cadence data accounting forthe broadening of the eclipse due to the 30 minute cadence Wethen use the secondary eclipse depth to determine the averagealbedo for the group In the short cadence data we found that agroup of close-in sub-Saturn candidates (1 to 6 Earth radii) wasmore reflective (geometric A ~ 022) than typical hot Jupiters(geometric A ~ 006 to 011 Demory 2014 ApJL 789 L20) Withthe larger number of candidates available in long cadence weimprove the resolution in radius and consider groups of candidateswith radii between 1 and 2 2 and 4 and 4 and 6 Earth radii We alsomodify our averaging technique to search for refracted light justbefore and after transit in the Kepler candidate light curves asmodelled by Misra and Meadows (2014 ApJL 795 L14)

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Author(s) Holly A Sheets Drake Deming Giada Arney Victoria MeadowsInstitution(s) 1 Astronomy Department University ofWashington 2 Department of Astronomy University ofMaryland

40408 ndash Mechanisms controlling the number andlatitudinal spacing of jets-streams on multiple jetplanets from terrestrial planets to gas giantsZonal jets dominate the atmospheric dynamics of a wide range ofplanetary systems as observed in all Solar System planetaryatmospheres and even observed on exoplanets Specifically whenthe ratio between the eddy length scale and the planetary scalebecomes small these planetary atmospheres develop multiple jetsIn this study we use an idealized general circulation model todemonstrate how such multiple-jets are formed and what controlstheir latitudinal width and spacing We find that for each latitudeover a wide range of parameters the jet spacing scales with theRhines scale The simulations show the presence of a criticallatitude where poleward (equatorward) of this latitude the Rhinesscale is larger (smaller) than the Rossby deformation radiusPoleward of this latitude a classic geostrophic turbulence pictureappears with a -53 spectral slope of inverse energy cascade fromthe deformation radius up to the Rhines scale A shallower slopethan the classic -3 slope of forward cascade is found from thedeformation radius down to the viscosity scale due to the broadinput of baroclinic eddy kinetic energy At these latitudeseddy-eddy interactions transfer barotropic eddy kinetic energyfrom the input scales of baroclinic eddy kinetic energy up to the jetscale and down to smaller scales We provide scaling laws for thenumber of eddy driven jets their latitudinal width and speed as afunction of a broad range of planetary parameters

Author(s) Yohai Kaspi Rei ChemkeInstitution(s) 1 Weizmann Institute of Science

40409 ndash Equilibrium and Disequilibrium Chemistryin Evolved Exoplanet AtmospheresIt has been found that sub-Neptune-sized planets although notexisting in our Solar System are ubiquitous in our interstellarneighborhood This revelation is profound because due to theirspecial sizes and proximity to their host stars Neptune- andsub-Neptune-sized exoplanets may have highly evolvedatmospheres I will discuss helium-dominated atmospheres as oneof the outcomes of extensive atmospheric evolution on warmNeptune- and sub-Neptune-sized exoplanets Due to depletedhydrogen abundance the dominant carbon and oxygen speciesmay not be methane or water on these evolved planetsEquilibrium and disequilibrium chemistry models are used tocompute the molecular compositions of the atmospheres and theirspectral features Applications to GJ 436 b and other Neptune- andsub-Neptune-sized exoplanets will be discussed As theobservations to obtain the spectra of these planets continue toflourish we will have the opportunity to study unconventionalatmospheric chemical processes and test atmosphere evolutiontheories

Author(s) Renyu HuInstitution(s) 1 Jet Propulsion Laboratory

405 ndash Galilean Satellites40501D ndash The spatial structure and temporalvariability of Ganymedersquos auroral ovals from HubbleSpace Telescope observationsWe analyze spectrally and spatially resolved images of GanymedersquosFUV-auroral ovals obtained during the past two decades byHubblersquos Space Telescope Imaging Spectrograph (HSTSTIS) Wefind both spatial inhomogeneities of the brightness-distributionon the observed disk as well as temporal variation as a function ofGanymedersquos position relative to the Jovian current sheet Thebrightness of the ovals is not equally distributed along the ovalsie the Jupiter-facing side is always brighter than the anti-Jupiter

side at least by ~60 When Ganymede moves from high elevatedmagnetic latitudes towards the center region of the Jovian currentsheet the brightness of the aurora on the leading side increases byover 30 from ~80 Rayleigh up to ~108 Rayleigh Simultaneouslyinside the current sheet center the auroral ovals are displaced by anaverage of ~6deg of planetographic latitude ie the ovals shiftfurthermore down towards the planetographic equator on theleading side and up towards the poles on the trailing side Botheffects the increase of brightness and the moving of the ovals arecorrelated to increased plasma interaction inside the current sheetGanymedersquos electron-impact-excited auroral emissions are thoughtto be driven by electron acceleration by strong field-alignedcurrents at the boundary area between open and closed magneticfield lines of Ganymedersquos mini-magnetosphere The change of theauroral morphology is a direct response to the changing plasmaenvironment ie changing ram and thermal pressures Thus theinvestigation of the aurora proves to be a suitable diagnostic tool ofthe various processes that contribute to Ganymedersquos complexplasma and magnetic field environment

Author(s) Fabrizio Musacchio Joachim Saur LorenzRoth Kurt D Retherford Melissa A McGrath Paul DFeldman Darrel F StrobelInstitution(s) 1 Department of Physics and Astronomy JohnsHopkins University 2 School of Electrical Engineering KTHRoyal Institute of Technology 3 SETI Institute 4 SouthwestResearch Institute 5 University of Cologne

40502 ndash Jupiters Satellite Europa Evidence for anExtremely Fine-Grained High Porosity SurfaceWe have measured the polarization phase curves of highlyreflective fine-grained particulate materials that simulateEuroparsquos predominately water ice regolith Our laboratorymeasurements exhibit polarization phase curves that areremarkably similar to results reported by experienced astronomers(Rosenbush et al 1997 2015) Our previous reflectance phasecurve measurements of the same materials were in agreement withthe same astronomical observers In addition we found that thesematerials exhibit an increase in circular polarization ratio withdecreasing phase angle This is consistent with coherentbackscattering (CB) of photons in the regolith (Nelson et al 20002002) Shkuratov et al (2002) report that the polarizationproperties of these particulate media are also consistent with theCB enhancement process (Shkuratov 1989 Muinonen 1990)We have reconfigured a goniometric photopolarimeter (Nelson etal 2000 2002) to undertake measurements of the polarizationphase curves of these particulate materials Our reconfigurationapplies the Helmholtz Reciprocity Principle (Hapke 2012 p264) -ie we present our samples with linearly polarized light andmeasure the intensity of the reflected component These laboratorymeasurements are physically equivalent to the astronomicalpolarization measurements We report here the polarization phasecurves of high albedo Aluminium Oxide particulates of size 01ltDlt30 microm five of which are 15 microm or smaller in diameter The phaseangle varied from 005 to 15 degrees We find for particles less thanor equal to 15 microm that the depth and position of the polarizationphase curve minimum the crossover point and the slope at thecrossover point all correlate with particle size and porosity We findzero polarization for the particle sizes greater than 2 micromOur results replicate the astronomical data and are consistent witha Europan regolith that is extremely fine-grained with remarkablyhigh porosity probably with void space exceeding 90 The EuropaClipper Mission science value would be strongly enhanced bymeasuring the polarization phase angle data of the GalileansatellitesThis work is supported by NASArsquos Cassini Saturn Orbiter mission

Author(s) Robert M Nelson Mark D Boryta Bruce WHapke Ken S Manatt Adaeze Nebedum Desiree Kroner Yuriy Shkuratov Vladimir Psarev William D SmytheInstitution(s) 1 Jet Propulsion Laboratory 2 KarazinUniversity 3 Mount San Antonio College 4 Planetary ScienceInstitute 5 University of California at Los Angeles 6 Universityof Pittsburgh

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122

40503 ndash Using Lava Tube Skylights To Derive LavaEruption Temperatures on IoThe eruption temperature of Iorsquos silicate lavas constrains Iorsquosinterior state and composition [1] We have examined thetheoretical thermal emission from lava tube skylights abovebasaltic and ultramafic lava channels Assuming that tube-fed lavaflows are common on Io skylights could also be commonSkylights present steady thermal emission on a scale of days tomonths We find that the thermal emission from such a targetmeasured at multiple visible and NIR wavelengths can provide ahighly accurate diagnostic of eruption temperature However thesmall size of skylights means that close flybys of Io are necessaryrequiring a dedicated Io mission [2] Observations would ideally beat night or in eclipse We have modelled the thermal emissionspectrum for different skylight sizes lava flow stream velocitiesend-member lava compositions and skylight radiation shapefactors determining the resulting flow surface cooling rates Wecalculate the resulting thermal emission spectrum as a function ofviewing geometry From the resulting 0709 μm ratios we see aclear distinction between basaltic and ultramafic compositions forskylights smaller than 20 m across even if sub-pixel Our analysiswill be further refined as accurate high-temperature short-wavelength emissivity values become available [3] This work wasperformed at the Jet Propulsion Laboratory-California Institute ofTechnology under contract to NASA We thank the NASA OPRProgram for support References [1] Keszthelyi et al (2007) Icarus192 491-502 [2] McEwen et al (2015) The Io Volcano Observer(IVO) LPSC-46 abstract 1627 [3] Ramsey and Harris (2015)IAVCEI-2015 Prague Cz Rep abstract IUGG-3519

Author(s) Ashley Gerard Davies Laszlo P Keszthelyi Alfred S McEwenInstitution(s) 1 JPL 2 University of Arizona 3 USGSAstrogeology Division

40504 ndash The Spatial Distribution of Volcanic Eventson Io in 2013-2015The spatial distribution of heat flow on Io is a key prediction of tidalheat dissipation models and therefore provides an importantconstraint for understanding Iorsquos interior However the majority ofour knowledge about eruption locations is derived from geologicalfeatures tracing long time periods (eg Hamilton et al 2013) andfrom activity during the Galileo era (eg Davies et al 2015 Veederet al 2015)We report on new results from a campaign to image Io in thenear-infrared with adaptive optics on the Keck and Gemini Ntelescopes We observed Io on 93 nights between August 2013 andJune 2015 detecting volcanic activity at dozens of hot spotlocations We present the spatial distribution of the observederuption sites during this period and compare this with thedistributions inferred from past hot spot and patera locations byprevious authors We discuss the locations of eruptions of differentmagnitudes including a preponderance of bright activity atlatitudes polewards of 45 degrees in both hemispheres and anapparent spatial clustering of activity in the months following largeeruptions Finally we address the durations of the detectederuptions as well as connecting our findings to the EXCEEDMissionrsquos observations of the Io plasma torus during the same timeperiod

Author(s) Katherine R de Kleer Imke de PaterInstitution(s) 1 UC Berkeley

40505 ndash Insights into Iorsquos volcanoes by combiningground-based and spacecraft dataActive volcanoes dominate Iorsquos surface They dominate Iorsquosinfrared flux they add to the composition of the atmosphere andare the origin of material in the Io Plasma torus Understandingwhen how and why they erupt is the key to understandingmaterial input into the Jovian system They are also key tounderstanding the dominant heating process in the solar systemtidal heating because Io is where that process has the greatest andmost obvious effectThe Galileo spacecraft obtained data from Io during periods less

than a few days on more than 30 occasions between mid 1996 andlate 2001 The New Horizons spacecraft observed Io for a 2-weekperiod in early 2007 Other spacecraft while not as useful forvolcano observations observed the Jupiter system in recentdecades The Cassini spacecraft flew by the Jupiter system in 2001and the JAXA Hisaki (SPRINT-A) spacecraft observed the Jovianmagnetosphere in 2014 The Juno spacecraft will reach Jupiter in ayear An mission specifically to Io has been submitted to theDiscovery Program and will be allowed to the New FrontiersProgram starting with call number 5NASArsquos Infrared Telescope Facility (IRTF) has been used toobserve Iorsquos volcanoes for more than two decades Data consist ofimages in 3 wavelengths (22 35 and 48 microns) with shortexposures for shift-and-add processing to increase spatialresolution In addition Jupiter occultations of Io while it is ineclipse enable the accurate determination of the intensity and 1-Dlocation of active volcanoes on the Jupiter-facing hemisphere of Iobut only in a single wavelength IRTF observations were obtainedon more than 100 nights concentrated at times when a spacecraftis also observing IoCombining data from multiple instruments and facilities hasallowed us to determine length of eruption events such as Lokiand Tvashtar as well as temperatures of the erupted lavas We willshow how IRTF and New Horizons data specifically have beencombined to yield greater information into the nature of Iorsquosvolcanism and we will discuss how ground-based observationsduring future missions can be optimized for the greatest scientificoutput

Author(s) Julie A Rathbun John R Spencer RobertHowell Rosaly LopesInstitution(s) 1 JPL 2 Southwest Research Institute 3 Univof Redlands 4 University of Wyoming

40506 ndash Sea salt irradiation experiments relevant tothe surface conditions of ocean worlds such as Europaand EnceladusWe have conducted a set of laboratory experiments to measurechanges in NaCl KCl MgCl and mixtures of these salts as afunction of exposure to the temperature pressure and radiationconditions relevant to ice covered ocean worlds in our solar systemReagent grade salts were placed onto a diffuse aluminum target atthe end of a cryostat coldfinger and loaded into an ultra-highvacuum chamber The samples were then cooled to 100 K and thechamber pumped down to ~10 Torr achieving conditionscomparable to the surface of several moons of the outer solarsystem Samples were subsequently irradiated with 10 keVelectrons at an average current of 1 microAWe examined a range of conditions for NaCl including pure saltsgrains (~300 microm diameter) salt grains with water ice deposited ontop and evaporites For the evaporites saturated salt water wasloaded onto the cryostat target the chamber closed and thenslowly pumped down to remove the water leaving behind a saltevaporate for irradiationThe electron bombardment resulted in the trapping of electrons inhalogen vacancies yielding the the F- and M- color centers Afterirraditiation we observed yellow-brown discoloration in NaCl KClwas observed to turn a distinct violet In NaCl these centers havestrong absorptions at 450 nm and 720 nm respectively providing ahighly diagnostic signature of otherwise transparent alkali halidesmaking it possible to remotely characterize and quantify thecomposition and salinity of ocean worlds

Author(s) Kevin P Hand Robert W CarlsonInstitution(s) 1 JPL

40507 ndash Linear spectral modeling of ground-basedobservations of Europa (ESOVLTSINFONI)Jupiterrsquos moon Europa may harbor a global salty subsurface liquidwater ocean (Kivelson et al 2000) and its surface should containimportant clues about its composition However debate stillpersists about the nature of the surface chemistry and the relativeroles of exogenous versus endogenous processing Recently Rothet al (2014) reported the presence of activity by the detection of

1 32

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123

plumes reinforcing Europa as a major target of interests ofupcoming space missions such as the ESA L-class mission JUICETo continue the investigation of the composition of the surface ofEuropa a global mapping campaign of the satellite was performedbetween October 2011 and January 2012 with the integral fieldspectrograph SINFONI on the Very Large Telescope (VLT) in ChileThe high spectral binning of this instrument (05 nm) is suitable todetect any narrow signature in the wavelength range 145-245 μmThe spatially resolved spectra we obtained over five epochs nearlycover the entire surface of Europa with a pixel scale of 125 by 25mas (~35 by 70 km on Europarsquos surface)We perform linear spectral modeling using 4 types of species water-ice (both crystalline and amorphous) sulfuric acid hydratesulfate salts and Cl-rich salts At first order spectra on the leadingside are as expected dominated by water-ice distorted andasymmetric absorption features whereas sulfuric acid hydratethought to originate from Iogenic sulfur ion bombardment isclearly predominant on the trailing side (Carlson et al 2005)Saltsare also required to fit any SINFONI spectrum with the followingnotable result when NaK-bearing chlorines instead ofMg-sulfates are used the fits are improved whatever the regionThe feature centered at ~207 microm previously associated to themagnesium sulfates (Brown et al 2013) is also observed in theSINFONI spectra and can be reproduced by some chlorine saltsGlobal abundance maps will be presented regional variations ofabundances will be discussed and the question of the endogenic orexogenic origin of salts will be addressed Finally a preliminarycomparison with similar SINFONI data of Ganymede and Callistowill be presented

Author(s) Nicolas Ligier Franccedilois Poulet John Carter Yves Langevin Christophe Dumas Florian GourgeotInstitution(s) 1 European Southern Observatory (ESO) 2Institut dAstrophysique Spatiale (IAS) 3 Observatorio Nacional(ON)

40508 ndash Thermal Coupling Between the Ocean andMantle of Europa Implications for Ocean ConvectionMagnetic induction signatures at Europa indicate the presence of asubsurface ocean beneath the cold icy crust The underlying mantleis heated by radioactive decay and tidal dissipation leading to athermal contrast sufficient to drive convection and active dynamicswithin the ocean Radiogenic heat sources may be distributeduniformly in the interior while tidal heating varies spatially with apattern that depends on whether eccentricity or obliquity tides aredominant The distribution of mantle heat flow along the seafloormay therefore be heterogeneous and impact the regional vigor ofocean convection Here we use numerical simulations of thermalconvection in a global Europa-like ocean to test the sensitivity ofocean dynamics to variations in mantle heat flow patterns Towardsthis end three end-member cases are considered an isothermalseafloor associated with dominant radiogenic heating enhancedseafloor temperatures at high latitudes associated with eccentricitytides and enhanced equatorial seafloor temperatures associatedwith obliquity tides Our analyses will focus on convective heattransfer since the heat flux pattern along the ice-ocean interfacecan directly impact the ice shell and the potential for geologicactivity within it

Author(s) Krista M Soderlund Britney E Schmidt Johannes Wicht Donald D BlankenshipInstitution(s) 1 Georgia Institute of Technology 2 Max PlanckInstitute for Solar System Research 3 University of Texas Institutefor Geophysics

406 ndash Harold Masursky Award The CSWASurvey on Workplace Climate andAnti-Harassment Policies Christina Richey(NASA HQ)40601 ndash The CSWA Survey on Workplace Climate andAnti-Harassment Policies

Workplace climate can promote or hinder scientific productivityand innovation The Committee on the Status of Women inAstronomy (CSWA) Survey on Workplace Climate sought todiscover whether scientists in the astronomical and planetaryscience communities experienced a hostile work environment Thesurvey investigated the extent to which negative experiences 1)were motivated by the targets identity (eg gender genderidentity sexual orientation ability status religion neurodiversityor race and ethnicity) and 2) affected the extent to whichrespondents felt safe in their workplaces 426 participants wererecruited for an online survey This presentation will include thepreliminary results from respondents experiences in the last fiveyears Notable conclusions include 1 Scientists in theastronomical and planetary science communities experience andwitness inappropriate language verbal harassment and physicalassault 2 Abuses that relate to gender are those that appear in thegreatest proportion in this sample 3 Inappropriate commentsharassment and assault lead to a number of scientists feelingunsafe in their workplaces and pursuing fewer scholarlyopportunities as a direct result of these experiences Thispresentation in addition to highlighting results from the recentCSWA Survey will also include a definition for harassment andhighlight the types of harassment that are frequently encounteredby scientists as well as highlight techniques for dealing withharassment both in the workplace and at conferences

Author(s) Christina RicheyInstitution(s) 1 NASA HQ

407 ndash Rosetta at Perihelion The JourneyContinues Paul Weissman (PlanetaryScience Institute)40701 ndash Rosetta at Perihelion The JourneyContinuesESArsquos Rosetta spacecraft with participation by NASA has been inorbit around the nucleus of comet 67PChuryumov-Gerasimenkofor over one year It has been a year of great discoveries andaccomplishments including the first successful spacecraft landingon the surface of a cometary nucleus (and the second and the thirdlandings) The discoveries include 1) the unusual shape of thebi-lobed nucleus 2) the substantial change of the nucleus rotationperiod (which continues to evolve) 3) the high dust-to-gas ratio 4plusmn 1 (by mass) 4) the low bulk density of the nucleus 050 gcm 5) the high deuteriumhydrogen ratio of the coma water molecules53 x 10 more than 3 times the terrestrial value 6) the highlycomplex and different terrains on the nucleus surface 7) the lack ofany intrinsic magnetic field 8) the existence of cylindrical pits inthe nucleus surface typically ~200 m in diameter and ~180 mdeep 9) the existence of ldquogoose bumprdquo terrain which may provideclues to the accretion of the comet nucleus 10) the existence ofmany similarly-sized boulders on the nucleus surface and muchmore The spacecraft and comet passed through perihelion onAugust 13 2015 which has been marked by substantialvolatile-rich outbursts from the cometary nucleus The Rosettamission has now been extended to September 2016 when thecomet and spacecraft will be approaching 4 AU outbound from theSun This talk is dedicated to the memory of Dr Claudia JAlexander US Rosetta Project Scientist who passed away in Julyof this year Her tireless efforts and tremendous enthusiasm onbehalf of Rosetta contributed greatly to the success of the mission

Author(s) Paul R Weissman Matthew Taylor Claudia JAlexanderInstitution(s) 1 European Space Agency 2 Jet PropulsionLaboratory 3 Planetary Science Institute

408 ndash 20 Years of Exoplanets From SurveysTowards Characterization Emily Rauscher(University of Michigan)

2 2 22 1 3

3 12 3

1

3

-4

3 12

124

40801 ndash 20 Years of Exoplanets From SurveysTowards CharacterizationTwenty years ago the discovery of the first planet outside of oursolar system ushered in a new subfield of exoplanet study In theyears since the number of known planets has skyrocketed into thethousands due to an ever-expanding pool of detection methodsprojects and missions and substantial improvements in techniqueThese remarkable discoveries have revealed an exoplanetpopulation that is highly diverse in many cases breakingexpectations set by the single example of our own solar system andproviding us with the opportunity to study planets under a widerange of physical conditions Equally as exciting as the increasingnumber of known exoplanets within the last dozen years we haveseen the move from exoplanet discovery to characterization weare currently able to measure atmospheric properties of many ofthe brightest exoplanets We are now in an era where we can studythe diversity of atmospheric conditions for dozens of exoplanetsincluding measurements of their temperatures albedoscompositions and in some cases even more detailed informationabout their two- or three-dimensional atmospheric structures andcirculation patterns In this talk I will review the current state oftheory and observations the lessons we have learned and thequestions and techniques that direct future work

Author(s) Emily RauscherInstitution(s) 1 University of Michigan

409 ndash Galilean Satellites40901 ndash Mutual Occultation Observations of VolcanicHot Spots on Io in 2015During spring 2015 we observed a series of mutual occultations andeclipses of Io using the SpeX instrument on the NASA InfraredTelescope Facility (IRTF) Mutual event lightcurves were obtainedon 4 Feb 18 Feb 15 Mar and 22 Mar in the Lp (38 micron)filter with observations on 11 Feb and on 8 and 10 Mar lost toweather Such lightcurves can potentially provide the highestspatial resolution observations of Ios volcanic hotspots possiblefrom ground-based observations The geometry of the recentevents was particularly favorable for studies of the Loki Pateraregion but unfortunately Loki remained relatively faint during the2015 series An eruption of Pillan was observed on 18 Feb and isdiscussed in more detail by de Pater et al (2015) at this meetingWhile the relative faintness of Loki during the recent series limitsthe value of the new observations for studying that source recentimprovements to the Galilean satellite ephemerides also allow us tosignificantly improve the analysis of previous Loki occultationsfrom 1985 1991 1997 and 2003 In that earlier work it wasnecessary to allow adjustable offsets in the relative position of thesatellites to accommodate ephemeris uncertainty That in turnlimited the accuracy with which hot regions within Loki Pateracould be fixed and limited the ability to test different models forPatera activity Initial analysis of the most recent event seriesindicates that such arbitrary adjustments are no longer necessaryWe will present the occultation lightcurves for the most recentseries and the constraints on the location of Loki activity providedby those observations and from earlier occultation series

Author(s) Robert R Howell John R Spencer Julie ARathbun Jay D GoguenInstitution(s) 1 JPL 2 Planetary Science Institute 3 SwRI 4Univ of Wyoming

40902 ndash Large Binocular Telescope Observations ofEuropa Occulting Ios Volcanoes at 48 μmOn 8 March 2015 Europa passed nearly centrally in front of Io TheLarge Binocular Telescope observed this event in dual-apertureAO-corrected Fizeau interferometric imaging mode using themid-infrared imager LMIRcam operating behind the LargeBinocular Telescope Interferometer (LBTI) at a broadbandwavelength of 48 μm (M-band) Occultation light curves generatedfrom frames recorded every 123 milliseconds show that both Lokiand PelePillan were well resolved Europas center shifted by 2

kilometers relative to Io from frame-to-frame The derived lightcurve for Loki is consistent with the double-lobed structurereported by Conrad et al (2015) using direct interferometricimaging with LBTI

Author(s) Michael F Skrutskie Albert Conrad AaronResnick Jarron Leisenring Phil Hinz Imke de Pater Katherine de Kleer John Spencer Andrew Skemer Charles EWoodward Ashley Gerard Davies Denis DefreacutereInstitution(s) 1 Amherst College 2 Large Binocular TelescopeObservatory 3 NASAJPL 4 Southwest Research Institute 5Univ of Minnesota 6 Univ Of Virginia 7 University of Arizona8 University of California Berkeley

40904 ndash Search for Trace Species at EuropaUnderstanding the present surface composition of Europa providescritical information about its potential habitability From Earth wecurrently have very few tools at our disposal to measure Europarsquoscomposition Two notable exceptions are Keck NIR spectroscopy(cf Brown and Hand 2013) and Hubble Space Telescope UVspectroscopy (cf Cunningham et al 2015) In March 2015 weobtained 5 orbits of deep UV spectroscopy of Europa using theCosmic Origins Spectrograph covering wavelength range1170ndash1760 Aring The purpose of the observations was to detect tracespecies in Europarsquos exosphere which is generated by chargedparticle sputtering of Europarsquos water ice surface The compositionof the exosphere therefore provides an indirect measurement ofsurface composition Furthermore if active plumes are present thecomposition of the exosphere may also reflect the composition ofEuroparsquos subsurface water reservoir Of particular interest in theobserved wavelength range are multiplets of atomic chlorinebecause chlorine is predicted to be a major constituent of Europarsquosocean (Kargel et al 2000) and Na and K chlorides are expected tobe major constituents of the icy shell (Zolotov and Shock 2001Zolotov and Kargel 2009) The present situation at Europa isanalogous to that at Io in the late 1990s when chlorine ions werefirst detected in the plasma near Io (Kuppers and Schneider 2000)motivating searches for atomic chlorine and chlorine-bearingspecies that were subsequently detected in Iorsquos atmosphere(Lellouch et al 2003 Feaga et al 2004) Galileo plasmameasurements have detected chlorine ions near Europa (Volwerket al 2001) which has motivated the present search for chlorine inEuroparsquos exosphere We will present the new COS spectra ofEuropa and discuss the implications of the trace species that havebeen detected in these data

Author(s) Melissa McGrath William Sparks JohnSpencerInstitution(s) 1 SETI Institute 2 STScI 3 SWRI

40905 ndashThe distinct spectrum of large-scale chaos on Europafrom 1-4 micronWe present new spatially-resolved reflectance spectra of thesurface of Europa obtained with Keck NIRSPEC and adaptiveoptics These include the first spatially-resolved high-quality 3-4micron spectra on Europa In recent work (Fischer et al 2015 inreview) we show that Europas surface consists of three majorcompositional units at the ~100 km scale one of which isgeographically associated with large-scale chaos and thereforeendogenous processes We focus on this region we will present thefirst moderate-resolution spectrum of large-scale chaos from14-25 and 31-40 micron We will also present cryogeniclaboratory spectra of candidate materials from 1-4 micron anddiscuss the implications for identifying Europas nativecomposition

Author(s) Patrick D Fischer Michael E Brown Kevin PHandInstitution(s) 1 Caltech 2 JPL

40906 ndash Time Evolution of Iorsquos volcanoes Pele andPillan from 1996 ndash 2015 as derived from Galileo NIMSKeck Gemini IRTF and LBTI observations

1

4 32 1

6 21 7 7 8

8 4 75 3 7

1 23

1 12

125

We present highlights of our observations of Pele and Pillan on Ioand a multi-decade timeline of thermal emission intensities in bothregions Io was regularly observed by Galileo NIMS during1996-2001 Since 2001 the satellite has been imaged semi-regularlywith NIRC2 coupled to an adaptive optics system on the 10-mKeck telescope In 1997 Galileo NIMS observed a large and highly-variable eruption close to Pillan Mons this eruption lasted severalmonths [1] Since that time no eruptions had been seen (but timecoverage was scarce) until our Keck images on 14 August 2007revealed an active and highly-energetic eruption at a location closeto that of the 1997 eruptions A one-temperature blackbody fit tothe data revealed a (blackbody) temperature of 840 plusmn 40 K over anarea of 17 km with a total power output of ~500 GW UsingDaviesrsquo (1996) Io Flow Model [2] we find that the oldest lavapresent is less than 1-2 hours old having cooled down from theeruption temperature of gt1400 K to ~710 K This young hot lavasuggests that an episode of lava fountaining was underway Since2007 several eruptions have been seen in the Pillan region The 18February 2015 eruption was discovered during a mutualoccultation event with the NASA IRTF This event was(serendipitously) subsequently imaged with the Large BinocularTelescope Interferometer (LBTI) on 8 March 2015 during a mutualevent occultation and again with the IRTF on 15 March The sitewas imaged with the Keck and Gemini-N telescopes between 27March and May 5 during which time the intensity graduallydecreased Interestingly the precise location of the eruption hadshifted to the north-west from Pillan Patera where the initial (18Feb) eruption had taken place In contrast to the episodicity ofPillan Pele has been remarkably consistent in its thermal emissionduring the Galileo era [1] through February 2002 when ablackbody temperature of 940 plusmn 40 K and an area of 65 km wasmeasured Since that time however the radiant flux from this largeoverturning lava lake has gradually subsided over the next decadeby a factor of ~4 [1] Davies et al (2001) JGR 106 33079-33103[2] Davies (1996) Icarus 124 45-61

Author(s) Imke de PaterInstitution(s) 1 UC Berkeley

410 ndash Enceladus41001 ndash Resolving Enceladus thermal emission at the10s of meters scale along Baghdad Sulcus usingCassini CIRSOn 14 April 2012 Cassini executed one of its closest flyby to theSouth Pole of Enceladus with the primary goal to study the moonrsquosgravity During this flyby the Composite InfraRed Spectrometer(CIRS) was orientated such that its three focal planes were draggedacross Baghdad sulcus The instrument was specifically configuredto record interferograms with 52 seconds duration CIRS focalplane 1 (17 to 1000 microm) single circular detector provided a spatialresolution of about 300 meters CIRS focal plane 3 and 4 (9 to 17microm and 7 to 9 microm) are 2 1x10 detectors arrays Both arrays wereused in pair mode leading to 5 elements per focal plane and aresolution of about 43 meters across trackThe ground-track speed was so fast during this observation thatthis was enough time to observe the entire South Polar Region in asingle integration The thermal sources were passed over so rapidlythat it is not possible to reconstruct a spectrum from the resultinginterferogram instead features were created in the interferogramwhenever the scene temperature changed The signature of thesefeatures was also altered by bit trimming and band-pass filterconvolution To enable interpretation of the interferograms wedeveloped an innovative new approach that included thedevelopment of new instrument models modification of the flightsoftware and multiple in flight validation experiments Ourpreliminary results show temperature variability of the tiger stripesat 10s meters scale along track providing a constraint on thedistribution and temperature profile of Enceladusrsquo endogenicsourcesA similar methodology will be used for the penultimate targetedEnceladus flyby in Oct 28 2015 and we aim to also present ourpreliminary analysis of the results from this encounter

Author(s) Nicolas Gorius Carly Howett John Spencer Shane Albright Don Jennings Terry Hurford Paul Romani Marcia Segura Anne VerbiscerInstitution(s) 1 Catholic University of America 2 GoddardSpace Flight Center 3 Southwest Research Institute 4 System andSoftware Design 5 University of Maryland 6 University ofVirginia

41002 ndash Drawing the Curtain on EnceladusSouth-Polar EruptionsFor a comprehensive description of Enceladus south-polareruptions observed at high resolution they must be represented asbroad curtains rather than discrete jets Meanders in the fracturesfrom which the curtains of material erupt give rise to opticalillusions that look like discrete jets even along fractures with nolocal variations in eruptive activity implying that many featurespreviously identified as jets are in fact phantoms By comparingCassini images with model curtain eruptions we are able to obtainmaps of eruptive activity that are not biased by the presence ofthose phantom jets The average of our activity maps over all timesagrees well with thermal maps produced by Cassini CIRS We canbest explain the observed curtains by assuming spreading angleswith altitude of up to 14deg and zenith angles of up to 8deg for curtainsobserved in geometries that are sensitive to those quantities

Author(s) Joseph N Spitale Terry A Hurford Alyssa RRhoden Emily E Berkson Symeon S PlattsInstitution(s) 1 Arizona State University 2 NASA GoddardSpace Flight Center 3 Planetary Science Institute 4 RochesterInstitute of Technology 5 University of Arizona

41003 ndash Venting of CO at Enceladusrsquo SurfaceEnceladus has CO surface deposits in its South Polar Region thathave been recently mapped by J-P Combe et al (2015 AGU FallMeeting) Assuming that these are CO frost we show how theycan be formed We use an ocean-water circulation model [1] thatspecifies pressure gradients that drive water to the surface from arelatively gas-rich subsurface ocean We now examine themovement of CO to the surface formation of shallow CO gaspockets in the ice and the venting of CO when at least some ofthe gas freezes to form frost If the local heat flow is known (cf[2]) then the depths of the corresponding gas pockets can becalculated References [1] Matson et al (2012) Icarus 221 53-62[2] Howett et al (2011) J Geophys Res 116 E03003Acknowledgements AGD thanks the NASA OPR Program forsupport

Author(s) Dennis L Matson Ashley G Davies Torrence VJohnson Jean-Philippe Combe Tom B McCord JaniRadebaughInstitution(s) 1 Bear Fight Institute 2 Brigham YoungUniversity 3 Jet Propulsion Laboratory-California Institute ofTechnology

41004 ndash Inside Enceladusrsquo plumes the view fromCassinirsquos mass spectrometerBetween early 2008 and late 2012 the Ion and Neutral MassSpectrometer (INMS) on Cassini measured particles deep insidethe plumes of Enceladus seven times from varying altitudes andlocations From these measurements and the models that usethem we have extracted information that can be used to constrainthe physical processes that create the plumes and govern theirsourceNeutral densities are high only when INMS is within view of thetiger stripes Inside the plumes INMS measures spatial variationsthat are consistent with Mach-4 jets superimposed on more-diffusevapor INMS measured vapor velocity directly during a portion ofone encounter finding a Mach-4 distribution centered on 12 kmsModeling of vapor sources distributed along the tiger stripes showthey contribute 20 to 75 of the total density depending on theencounter and assumptions on the discrete sources Model-fittedvelocities range from 500 to 1300 ms The INMS data also show3x variations in total density that are consistent with theorbit-phase variations detected in visual and IR remote

2

2

1

th

th

1 3 34 2 2 2

5 6

3 21 4 5

2

2

2

2 22

1 31 3 3

2

126

observations of dust plumes Only H O ions are observed clearlyinside the plumesAn ice grain entering INMS increases the counts for onemeasurement These spikes are the largest source of uncertainty(40) in vapor measurements but also provide independentmeasurements of ice grains The frequency of these ice grainsmatches the Cosmic Dust Analyzer counts for grains larger than 02μm Their orbit-phase variability as seen by INMS is also consistentwith VIMS dataWater vapor comprises at least 90 of the plumes with CO NH and CH positively identified and less than 1 each H is likely5-10 but its abundance is uncertain due to fractionation of H Oin the instrument A species (CO or N ) with a mass of 28 u is asabundant as CO The C group totals lt 05 and the C group lt001 The high-velocity encounters show carbon fractions oforganic molecules with masses gt 100 u During individualencounters CO and the 28-u species show differences that aredue at least in part to mass-dependent thermal spreading inhigh-velocity jets There has been no significant variation in totalcomposition between encounters

Author(s) Mark E Perry Dana M Hurley Ben D Teolis JHunter Waite Brian A Magee H Todd Smith ValeriyTenishev Joe H Westlake Ralph L McNuttInstitution(s) 1 Johns Hopkins Applied Physics Lab 2Southwest Research Institute 3 University of Michigan

41005 ndash Modeling of the Enceladus water vapor jetsfor interpreting UVIS star and solar occultationobservationsOne of the most spectacular discoveries of the Cassini mission isjets emitting from the southern pole of Saturnrsquos moon EnceladusThe composition of the jets is water vapor and salty ice grains withtraces of organic compounds Jets merging into a wide plume at adistance are observed by multiple instruments on Cassini Recentobservations of the visible dust plume by the Cassini ImagingScience Subsystem (ISS) identified as many as 98 jet sourceslocated along ldquotiger stripesrdquo [Porco et al 2014] There is a recentcontroversy on the question if some of these jets are ldquoopticalillusionrdquo caused by geometrical overlap of continuous sourceeruptions along the ldquotiger stripesrdquo in the field of view of ISS [Spitaleet al 2015] The Cassinirsquos Ultraviolet Imaging Spectrograph (UVIS)observed occultations of several stars and the Sun by the watervapor plume of Enceladus During the solar occultation separatecollimated gas jets were detected inside the background plume[Hansen et al 2006 and 2011] These observations directly providedata about water vapor column densities along the line of sight ofthe UVIS instrument and could help distinguish between thepresence of only localized or also continuous sources We useMonte Carlo simulations and Direct Simulation Monte Carlo(DSMC) to model the plume of Enceladus with multiple (orcontinuous) jet sources The models account for molecularcollisions gravitational and Coriolis forces The models result inthe 3-D distribution of water vapor density and surface depositionpatterns Comparison between the simulation results and columndensities derived from UVIS observations provide constraints onthe physical characteristics of the plume and jets The specificgeometry of the UVIS observations helps to estimate theproduction rates and velocity distribution of the water moleculesemitted by the individual jetsHansen C J et al Science 3111422-1425 (2006) Hansen C J etal GRL 38L11202 (2011) Porco CC et al Astron J 148 45(2014) Spitale JN et al Nature 521 57-60 (2015)

Author(s) Ganna Portyankina Larry W Esposito Klaus-Michael Aye Candice J HansenInstitution(s) 1 Laboratory for Atmospheric and Space PhysicsUniversity of Colorado 2 Planetary Science Institute

41006 ndash Modeling of the spatial profile of neutrals inthe plume of Enceladus observed by Cassini INMSMonte Carlo modeling of the vapor erupting from EnceladusrsquoSouth polar region is presented to demonstrate the influence ofphysical characteristics of the emitted vapor on the distribution of

particles at altitude The modeled sources include both localizedjets and eruptions distributed along the surface features calledldquotiger stripesrdquo The modeling reveals that density enhancements ataltitude can be displaced from the source location Thedisplacement can be produced by the angle of emission Howeverin some cases it is caused by superposition of material fromadjacent sources Assuming different molecules are emitted at thesame bulk velocity and the same temperature differences in theamount of spreading for the different species emerges owing to thedependence of thermal velocity on mass The altitude of thesuperposition is mass dependent and contributes to differencesobserved in the mass 28 and mass 44 channels of the Cassini INMSduring Enceladus encountersWe present comparisons of INMS data with the model for fourCassini Enceladus flybys INMS data are modeled using only thetiger stripe sources to reproduce the broad structure of the plumeThe difference between the data and the model is attributed to thepresence of stronger more-localized sources which are identifiedby their excess In particular an additional source is required formass 44 u on the Saturn-facing hemisphere of Baghdad Sulcus Itis apparent in 3 parallel Cassini flybys A relative decrease in thesource rate is observed for mass 28 u for E14 The lack ofsmall-scale spatial structure of high-density regions in the 28 uINMS observations compared to the more collimated structure ofthe 44 u INMS observations is consistent with increased thermalspreading for low-mass constituents of the plume This indicatesthat even less spatial structure should be expected for thedominant species in the plume--water

Author(s) Dana Hurley Mark Perry Hunter WaiteInstitution(s) 1 JHUAPL 2 SwRI

411 ndash Icy Satellites41101 ndash Searching for Thermal Anomalies on IcySatellites Step 1- Validation of the Three DimensionalVolatile-Transport (VT3D)In the last few decades thermal data from the Galileo and Cassinispacecraft have detected various anomalies on Jovian andSaturnian satellites including the thermally anomalous ldquoPacManrdquoregions on Mimas and Tethys and the Pwyll anomaly on Europa(Howett et al 2011 Howett et al 2012 Spencer et al 1999) Yetthe peculiarities of some of these anomalies like the weakdetection of the ldquoPacManrdquo anomalies on Rhea and Dione and thelow thermal inertia values of the widespread anomalies onequatorial Europa are subjects for on-going research (Howett et al2014 Rathbun et al 2010) Further analysis and review of all thedata both Galileo and Cassini took of these worlds will provideinformation of the thermal inertia and albedos of their surfacesperhaps highlighting potential targets of interest for future Jovianand Saturnian system missions Many previous works have used athermophysical model for airless planets developed by Spencer(1990) However the Three Dimensional Volatile-Transport(VT3D) model proposed by Young (2012) is able to predict surfacetemperatures in significantly faster computation timeincorporating seasonal and diurnal insolation variations This workis the first step in an ongoing investigation which will use VT3Drsquoscapabilities to reanalyze Galileo and Cassini data VT3D which hasalready been used to analyze volatile transport on Pluto isvalidated by comparing its results to that of the Spencer thermalmodel We will also present our initial results using VT3D toreanalyze the thermophysical properties of the PacMan anomalyprevious discovered on Mimas by Howett et al (2011) usingtemperature constraints of diurnal data from CassiniCIRS VT3Dis expected to be an efficient tool in identifying new thermalanomalies in future Saturnian and Jovian missionsBibliographyCJA Howett et al (2011) Icarus 216 221CJA Howett et al (2012) Icarus 221 1084CJA Howett et al (2014) Icarus 241 239JA Rathbun et al (2010) Icarus 210 763J R Spencer (1990) Icarus 83 27J R Spencer et al (1999) Science 284 1514L A Young (2012) Icarus 221 80

3 +

2 34 2

22

2 2 3

2

1 1 22 2 1

3 1 1

1 11 2

1 1 2

127

Author(s) Gary G Simmons Carly JA Howett Leslie AYoung John R SpencerInstitution(s) 1 Southwest Research Institute 2 University ofColorado-Boulder

41102 ndash Dark material on the classical Uraniansatellites What is it and where did it come fromDuring Voyager 2rsquos flyby of Uranus its Imaging Science Subsystem(ISS) camera captured tantalizing images of the icy gray-tonedsurfaces of the classical Uranian satellites Additionallyground-based near-infrared (NIR) observations of these moonshave detected a mixture of H O ice and a low albedo andpotentially carbonaceous constituent on their surfaces Analysis ofISS color maps demonstrated that the leading hemispheres of thesemoons are spectrally redder than their trailing hemispheres andboth the degree of reddening and the correlation between lowalbedo and spectrally red regions increases with distance fromUranus However ISS almost exclusively observed the southernhemispheres of these moons (subsolar point ~81ordm S) and we havecollected new observations of their northern hemispheres (currentsubsolar point ~29ordm N) By characterizing the distribution of thedark material we will be able to constrain the primary productionmechanism for this low albedo constituent Our preferredhypothesis is that the dark material represents accumulatedintraplanetary dust that originated on Uranusrsquo retrograde irregularsatellitesTo characterize the distribution of the spectrally red low albedomaterial on these moons we are measuring their spectral slopesusing visible wavelength (VIS) spectra and photometry gatheredover similar wavelengths to those sensed by ISS (~04 ndash 06 microm)Additionally we have collected NIR spectra of these satellites inorder to characterize the relative strengths of 152 and 202 micromH O ice bands which are modified by the presence of low albedocontaminants Our results indicate that the 152 and 202 microm H Obands are stronger on the leading hemispheres of these moonsand the hemispherical asymmetry in H O band strengthsdecreases with distance from Uranus Spectral modeling of theseNIR spectra will help discern between contaminant mixing andgrain size effects on the relative strength of the H O bands We willpresent our interpretation of the H O band strength results andour ongoing analysis of VIS spectral slopes for the classical Uraniansatellites

Author(s) Richard J Cartwright Joshua P Emery Michael P Lucas Noemi Pinilla-Alonso David E Trilling AndyS RivkinInstitution(s) 1 John Hopkins University Applied PhysicsLaboratory 2 Northern Arizona University 3 University ofTennessee

41103 ndash Structural diversity of the 3-micronabsorption band in Enceladusrsquo plume from CassiniVIMS Insights into subsurface environmentalconditionsWater ice particles in Enceladusrsquo plume display their diagnostic3-micron absorption band in Cassini VIMS data These nearinfrared measurements of the plume also exhibit noticeablevariations in the character of this band Mie theory calculationsreveal that the shape and location of the 3-micron band arecontrolled by a number of environmental and structuralparameters Hence this band provides important insights into theproperties of the water ice grains and about the subsurfaceenvironmental conditions under which they formed For examplethe position of the 3-micron absorption band minimum can beused to distinguish between crystalline and amorphous forms ofwater ice and to constrain the formation temperature of the icegrains VIMS data indicates that the water ice grains in the plumeare dominantly crystalline which could indicate formationtemperatures above 113 K [eg 1 2] However there are slight (butobservable) variations in the band minimum position and bandshape that may hint at the possibility of varying abundance ofamorphous ice particles within the plume The modeling resultsfurther indicate that there are systematic shifts in band minimumposition with temperature for any given form of ice but the

crystalline and amorphous forms of water ice are stilldistinguishable at VIMS spectral resolution Analysis of theeruptions from individual source fissures (tiger stripes) usingselected VIMS observations reveal differences in the 3-micronband shape that may reflect differences in the size distributions ofthe water ice particles along individual fissures Mie theory modelssuggest that big ice particles (gt3 micron) may be an importantcomponent of the plume[1] Kouchi A T Yamamoto T Kozasa T Kuroda and J MGreenberg (1994) AampA 290 1009-1018 [2] Mastrapa R M E WM Grundy and M S Gudipati (2013) in M S Gudipati and JCastillo-Rogez (Eds) The Science of Solar System Ices pp 371

Author(s) Deepak Dhingra Matthew M Hedman Roger NClarkInstitution(s) 1 Planetary Science Institute 2 University ofIdaho

41104 ndash Deriving the Structure and Composition ofEnceladusrsquo Plume from Cassini UVIS ObservationsCassinirsquos Ultraviolet Imaging Spectrograph (UVIS) has observed 4stellar and one solar occultation by Enceladusrsquo water vapor plumeThe July 2005 occultation observation established that water is theprimary constituent of the plume [1] and allowed us to calculatethe flux of water coming from the plume the 2007 occultationshowed super-sonic jets of gas imbedded within the plume [2] Thesolar occultation observation set upper limits for N as aconstituent of the plume and provided higher resolution data onthe jets [3] On 19 October 2011 epsilon and zeta Orionis weresimultaneously occulted by the plume The stars were in separatepixels on the detector separated by 24 mrad or ~20 km with thelower altitude star (epsilon Orionis) 18 km above the limb at itsclosest point The profile at two altitudes shows evidence for a newgas jet location possibly between dust jet 50 and 51 identified in[4]Results from the assemblage of these data sets with implicationsfor the composition and vertical structure of the plume and jetswill be described Gas being expelled from the ldquotiger striperdquo fissuresis largely on a vertical escape trajectory away from EnceladusUpper limits are set for water vapor near the limb at latitudes wellaway from the south pole at 3 x 10 cm Upper limits are set forthe amount of ethylene and H in the plume two species ofinterest to the chemistry of the plume [5] No hydrogen or oxygenemission features have been observed from Enceladusrsquo water vaporplume in contrast to the purported plumes at Europa probablydue to the very different plasma environment at Saturn Data havenow been processed consistently for all occultations with slightlydifferent results for water vapor supply to the Saturnmagnetosphere than previously reported Overall eruptive activityhas been steady to within ~20 from 2005 to 2011References [1] Hansen C J et al Science 3111422 (2006)Hansen C J et al Nature 456477 (2008) [3] Hansen C J et alGRL 38L11202 (2011) [4] Porco C C et al Ast J 14845(2014) [5] Glein C R et al GCA 162202 (2015)

Author(s) Candice Hansen Larry Esposito Josh Colwell Amanda Hendrix Ganna Portyankina Don Shemansky RobertWestInstitution(s) 1 JPL CIT 2 PSI 3 Space EnvironmentTechnologies 4 University of Central Florida 5 University ofColorado

41105 ndash The lsquoExcessrsquo Emission from the Warm SurfaceAdjacent to Active Fissures on Enceladus fromCombined VIMS and CIRS SpectraThe exciting discovery of thermal emission from the tiger stripefissures at the S pole of Enceladus is a major highlight of theCassini mission Both VIMS (Visible and Infrared MappingSpectrometer) and CIRS (Composite InfraRed Spectrometer)detect the thermal lsquoblackbodyrsquo spectrum emitted from the warmfissure areas The VIMS instrument is uniquely suited tomeasuring the hottest active locations because VIMS covers the 3to 5 micron wavelength range where the rising edge of the Planckfunction for these T~200 K areas dominates the emission

2 11 1

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spectrum At longer wavelengths the spectrum is morecomplicated because contributions from small hot areas and largercooler areas combine to form the broad emission spectrum that isdetected by the CIRS instrument at wavelengths gt67 microns It isthe combination of VIMS and CIRS spectra that paint a morecomplete portrait of the fissure heat transfer processes Usingspectra that span both the VIMS and CIRS wavelengths places astronger constraint on the T distribution near the fissures thanconsideration of the spectra from either instrument aloneWe show that when the best (= highest spatial resolution 800mpixel and smaller) VIMS and CIRS spectra of the fissure thermalemission are considered together there is a large (up to 400)component of lsquoexcessrsquo emission spanning 7 to 17 microns thatrequires explanation New analysis of ~2 km spatial resolutionVIMS spectra of the Damascus hot spot on 8132010 are similar tothe highest resolution 4142012 VIMS Baghdad spectraconfirming that differences in location or time between the bestVIMS and CIRS spectra do not explain away the excess Theobvious interpretation is that there are processes that transfer heatfrom the fissure eruption to the surface within 400 m of the fissurecenter in addition to heat conduction through the fissure wallsCandidate heat transfer processes include fallback of large warmlow velocity ice particles from the edges of the plume andcondensation of the low velocity component of water vaporexpanding outward from the edge of the plumeThis research was conducted at the Jet Propulsion LaboratoryCalifornia Institute of Technolgy Pasadena CA

Author(s) Jay D Goguen Bonnie J Buratti Robert RHowellInstitution(s) 1 JPL 2 University of Wyoming

41106 ndash A 1-D evolutionary model for icy satellitesapplied to EnceladusA 1-D long-term evolution code for icy satellites is presented whichcouples multiple processes water migration geochemicalreactions water and silicate phase transitions crystallizationcompaction by self-gravity and ablation The code takes intoaccount various energy sources tidal heating radiogenic heatinggeochemical energy released by serpentinization or absorbed bymineral dehydration gravitational energy and insolation Itincludes heat transport by conduction convection and advectionThe code is applied to Enceladus by guessing the initial conditionsthat would render a structure compatible with present-dayobservations and adopting a homogeneous initial structureAssuming that the satellite has been losing water continually alongits evolution it follows that it was formed as a more massive moreice-rich and more porous object and gradually transformed into itspresent day state due to sustained tidal heating Several initialcompositions and evolution scenarios are considered and theevolution is simulated for the age of the Solar System The resultscorresponding to the present configuration are confronted with theavailable observational constraints The present configuration isshown to be differentiated into a pure icy mantle several tens ofkm thick overlying a rocky core composed of dehydrated rock inthe central part and hydrated rock in the outer part Such adifferentiated structure is obtained not only for Enceladus but forother medium size ice-rich bodies as wellPredictions for Enceladus are a higher rockice mass ratio thanpreviously assumed and a thinner ice mantle compatible withrecent estimates based on gravity field measurements Althoughobviously the 1-D model cannot be used to explain localphenomena it sheds light on the internal structure invoked inexplanations of localized features and activities

Author(s) Dina Prialnik Uri MalamudInstitution(s) 1 Tel Aviv University

412 ndash Irregular Satellites41201 ndash The Himalia Satellite Group A Case Study onthe Dynamical Self-spreading of Families of IrregularSatellites and Asteroids

Many of the outer planets irregular satellites are grouped intofamilies thought to originate from collisional fragmentation(Nesvornyacute et al 2004 AJ) Interestingly families associated withthe largest irregulars are either more dispersed than expected (egJ6 Himalia Nesvornyacute et al 2003 AJ) or do not exist at all (eg S9Phoebe Ćuk et al 2003 DDA meeting 34) Christou (2005Icarus) found that gravitational scattering by Himalia of its owngroup could explain the large velocity dispersion found byNesvornyacute et al (2003 AJ) At the same time Christou identified anew type of dynamical mechanism that intermittently locks thenode of the satellite J10 Lysithea to that of Himalia The samemechanism but due to Ceres was recently found to operate withinthe Hoffmeister family dispersing its members and allowing anestimate of its age (Novaković et al 2015 ApJ)Here we revisit the issue of family self-dispersion aiming to betterunderstand it by studying its effects on the Himalia group For thiswe utilise (a) intensive test particle simulations on a larger scalethan those by Christou (2005 Icarus) (b) a semi-analyticaltreatment of the new resonance based on the secular theory ofcoorbital motion by Namouni (1999 Icarus) This has allowed us toobtain firmer constraints on the rate of dispersion over time and onhow the resonance affects the long-term evolution of the orbitalelements A principal result of this work is that particles near theresonance evolve differently than those away from it During themeeting we will present a new estimate of the familyrsquos age as wellas an analysis of the resonant structure and how it affects Himaliafamily members We will also discuss the broader implications forthe long-term evolution of orbital concentrations of small bodies inthe solar systemAstronomical research at the Armagh Observatory is funded by theNorthern Ireland Department of Culture Arts and Leisure (DCAL)

Author(s) Daohai Li Apostolos A ChristouInstitution(s) 1 Armagh Observatory

41202 ndash Lightcurves for 25 Irregular Satellites ofSaturnThis abstract reports rotational-lightcurve observations of irregularmoons of Saturn based on disk-integrated observations with theNarrow-Angle Camera of the Cassini spacecraft For 16 objectssynodic rotation periods have been derived at lt1 accuracy for 6others at lower accuracy or with an ambiguity with respect to theamount of maxima and minima The average of all 22 measuredperiods lies between 16 and 19 h For the 19 objects with periodsfaster than 24 h the average is ~125 hThe objects were observed at phase angles between 2deg and 143degAmong the lightcurves obtained at low phases (lt ~45deg) ~85exhibit 2 maxima and 2 minima while only ~15 show3max3min For mid-phase lightcurves (~45deg to ~90deg) the ratiobetween 2max2min and 3max3min lightcurves is almost equalAt high phases (gt ~90deg) only ~13 of the lightcurves display2max2min while ~23 show 3max3min or even 4max4min Forlow- and mid-phase angles the lightcurve amplitudes clearlyincrease with increasing phase While ~50 of the objects showlightcurves with amplitudes below ~04 mag at low phases wefound almost no such small amplitudes for mid and high phasesBetween mid- and high-phase angles the trend of magnitudeincrease lessens The most extreme measured amplitudes were~25 magNo object with a period close to the spin barrier for Main Beltasteroids (~23 h) was detected By assuming a bulk density of theSaturnian irregulars of ~1 g cm the fastest measured period of55 h would be close to the spin barrier for these objectsA comparison of the irregular moons rotation periods with fiveorbit parameters indicates possible weak correlations with two ofthem Periapses and co-latitude of the orbit pole (i with i = i forprograde i = 180deg-i for retrograde moons i is the objects orbitinclination) For moons with orbits of high i gt ~27deg no fast rotator(P lt 10 h) has been found and their average rotation period is~17x longer than for the low-i objects The five fastest rotators areall members of the low-i group A null hypothesis claiming thatobjects of the two inclination bins come from the same populationis rejected at the 95 confidence level

1 12

1 1

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-3

129

Author(s) Tilmann Denk Stefano MottolaInstitution(s) 1 DLR 2 Freie Universitaumlt

41204 ndash Radial Profiles of Saturnrsquos Phoebe RingIn 2009 the Spitzer observatory discovered a vast circumplanetarydust ring around Saturn sourced by its swarm of irregularsatellites This material had been hypothesized to exist in order toblanket Iapetusrsquo leading face and create its stark hemisphericaldichotomy Unfortunately observations from near-Earth spacecannot probe how far inward the Phoebe ring extends as they areoverwhelmed by scattered light from the planet Additionally todate such measurements have only been achieved of thermalemission in the mid-infraredBy contrast we present results from recent observations with theCassini spacecraft (in orbit about Saturn) at optical wavelengthsUsing a novel observational technique that exploits the movingshadow cast by Saturn we mitigate the scattered light andbackground and have been able to clearly extract the exceedinglyfaint Phoebe ring signal (line-of-sight optical depth of 10e-9surface brightness of roughly 27 magarcsec^2)Our extracted albedos are consistent with dark material liberatedfrom the irregular satellites Additionally we present reconstructedradial profiles over the broad range of distances from Saturnspanned by our observations We also connect these results totheoretical models of the size-dependent dynamics of Phoebe ringdust grains under the action of the relevant perturbations

Author(s) Daniel Tamayo Stephen Markham Matthew MHedman Joseph A BurnsInstitution(s) 1 Cornell University 2 University of Idaho 3University of Toronto at Scarborough

413 ndash 67PChuryumov-Gerasimenko41301 ndash The nucleus of comet 67P through the eyes ofthe OSIRIS camerasThe Rosetta spacecraft is studying comet 67PChuryumov-Gerasimenko from a close distance since August 2014 Onboard thespacecraft the two scientific cameras the OSIRIS narrow- and thewide-angle camera are observing the cometary nucleus its activityas well as the dust and gas environmentThis overview paper will cover OSIRIS science from the early arrivaland mapping phase the PHILAE landing and the escort phaseincluding the two close fly-bys With a first characterization ofglobal physical parameters of the nucleus the OSIRIS cameras alsoprovided the data to reconstruct a 3D shape model of the comet anda division into morphologic sub-units From observations ofnear-surface activity jet-like features can be projected onto thesurface and active sources can be correlated with surface featureslike cliffs pits or flat planes The increase of activity during andafter perihelion in August 2015 showed several outbursts whichwere seen as strong collimated jets originating from the southernhemisphereA comparison of results between different Rosetta instruments willgive further inside into the physics of the comets nucleus and itscoma The OSIRIS and VIRTIS instruments are particularly wellsuited to support and complement each other With an overlap inspectral range one instrument can provide the best spatialresolution while the other is strong in the spectral resolution Asummary on collaborative efforts will be given

Author(s) Carsten Guettler Holger Sierks CesareBarbieri Philippe Lamy Rafael Rodrigo Detlef Koschny Hans Rickman The OSIRIS Team Fabrizio Capaccioni Gianrico Filacchione Mauro Ciarniello Stephane Erard Giovanna Rinaldi Federico TosiInstitution(s) 1 Centro de Astrobiologiacutea CSIC-INTA 2European Space Research and Technology CentreESA 3 INAF 4LAM (Laboratoire dAstrophysique de Marseille) 5 Max PlanckInstitute for Solar System Research 6 Observatoire de Paris 7University of Padova 8 Uppsala University

41302 ndash Interpretation of spectrophotometric surface

properties of comet 67PChuryumov-Gerasimenko bylaboratory simulations of cometary analogsThe OSIRIS imaging system [1] onboard European Space AgencyrsquosRosetta mission has been orbiting the comet 67PChuryumov-Gerasimenko (67P) since August 2014 It provides an enormousquantity of high resolution images of the nucleus in the visiblespectral range 67P revealed an unexpected diversity of complexsurface structures and spectral properties have also been measured[2]To better interpret this data a profound knowledge of laboratoryanalogs of cometary surfaces is essential For this reason we haveset up the LOSSy laboratory (Laboratory for Outflow Studies ofSublimating Materials) to study the spectrophotometric propertiesof ice-bearing cometary nucleus analogs The main focus lies onthe characterization of the surface evolution under simulated spaceconditions The laboratory is equipped with two facilities thePHIRE-2 radio-goniometer [3] designed to measure thebidirectional visible reflectance of samples under a wide range ofgeometries and the SCITEAS simulation chamber [4] designed tostudy the evolution of icy samples subliming under lowpressuretemperature conditions by hyperspectral imaging in theVIS-NIR range Different microscopes complement the twofacilitiesWe present laboratory data of different types of fine grained iceparticles mixed with non-volatile components (complex organicmatter and minerals) As the ice sublimes a deposition lag ofnon-volatile constituents is built-up on top of the ice possiblymimic a cometary surface The bidirectional reflectance of thesamples have been characterized before and after the sublimationprocessA comparison of our laboratory findings with recent OSIRIS data[5] will be presented[1] Keller H U et al 2007 Space Sci Rev 128 26[2] Thomas N 2015 Science 347 Issue 6220 aaa0440[3] Jost B submitted Icarus[4] Pommerol A et al 2015 Planet Space Sci 109106-122[5] Fornasier S et al in press Icarus arXiv150506888

Author(s) Bernhard Jost Antoine Pommerol OlivierPoch Nathalie Carrasco Cyril Szopa Nicolas ThomasInstitution(s) 1 Center for Space and Habitability University ofBern 2 LATMOS-IPSL Universiteacute Versailles St-Quentin 3Physics Institute University of Bern

41303 ndash Photometric properties of the nucleus of67PChuryumov-Gerasimenko from OSIRISRosettaspace telescope and ground-based observationsIn-situ imaging of the nucleus of comet 67PChuryumov-Gerasimenko by the OSIRIS Narrow Angle Camera (NAC) allowsan in depth characterization of its photometric properties that canbe compared with remote observations thus helping in theinterpretation of other nuclei We performed a photometricanalysis of both unresolved and resolved NAC images of thenucleus obtained during twenty five observational campaignsspreading from 23 March to 6 August 2014 with up to twelve filterswhose spectral coverage extended from 271 to 986 nm An accuratephotometric calibration was obtained from the observations of asolar analog star 16 Cyg B We further combined this analysis withprevious observations obtained with the Hubble and Spitzer spacetelescopes and ground-based telescopes The analysis furtherincorporates the shape model and the rotational state the nucleusof 67P independently determined from the NAC images We willpresent results on the geometric albedo phase function color andthermal properties and put them in the broader context ofproperties of cometary nuclei

Author(s) Philippe L Lamy Guillaume Faury Imre Toth Laurent Jorda Robert Gaskell Olivier Groussin ClaireCapannaInstitution(s) 1 AKKA Technologies 2 Konkoly Observatory3 Laboratoire dAstrophysique de Marseille 4 Planetary ScienceInstitute

41304 ndash The Nucleus and Coma of Comet 67PC-G as

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Seen at Millimeter and Submillimeter Wavelengths bythe MIRO InstrumentThe Microwave Instrument for the Rosetta Orbiter (MIRO) is aUS instrument on the European Space Agencys Rosettaspacecraft currently flying along side comet 67PChuryumov-Gerasimenko MIRO is designed to study the nucleus and coma ofthe comet as a coupled system It makes broad-band continuummeasurements of the thermal emission of the nucleus at 190 and563 GHz (16 and 05 mm) which probe the thermal and dielectricproperties of the nucleus as a function of depth from ~1 mm to ~10cm When looking off the nucleus continuum emission from dustcan be used to constrain the abundance and size distribution ofparticles In addition to its continuum channels MIRO has a highresolution (44 kHz) spectrometer fixed tuned to submillimeterlines of H O H O H O CO NH and three CH OHtransitions All 8 lines have been observed yielding estimates ofthe abundance velocity and temperature of these species in thecoma This talk will provide an overview of the instrument and ourresults to date

Author(s) Mark D Hofstadter Samuel Gulkis Mark Allen Paul von Allmen Gerard Beaudin Nicolas Biver DominiqueBockelee-Morvan Mathieu Choukroun Jacques Crovisier Pierre Encrenaz Therese Encrenaz Margaret Frerking PaulHartogh Wing Ip Michael Janssen Christopher Jarchow Stephen Keihm Seungwon Lee Emmanuel Lellouch CedricLeyrat Ladislav Rezac Frederick Peter Schloerb ThomasSpilkerInstitution(s) 1 JPL 2 Max Planck 3 National CentralUniversity 4 Observatoire de Paris 5 Solar System Science andExploration 6 University of Massachusetts

41305 ndash Search for regional variations of thermal andelectrical properties of comet 67PCG probed byMIRORosettaSince June 2014 The MIRO (Microwave Instrument for RosettaOrbiter) on board the Rosetta (ESA) spacecraft observes comet67P-CG along its heliocentric orbit from 325 AU to 124 AU MIROoperates in millimeter and submillimeter wavelengths respectivelyat 190 GHz (156 mm) and 562 GHz (05 mm) While thesubmillimeter channel is coupled to a Chirp TransformSpectrometer (CTS) for spectroscopic analysis of the coma bothbands provide a broad-band continuum channel for sensing thethermal emission of the nucleus itselfContinuum measurements of the nucleus probe the subsurfacethermal emission from two different depths The first analysis(Schloerb et al 2015) of data already obtained essentially in theNorthern hemisphere have revealed large temperature variationswith latitude as well as distinct diurnal curves most prominent inthe 05 mm channel indicating that the electric penetration depthfor this channel is comparable to the diurnal thermal skin depthInitial modelling of these data have indicated a low surface thermalinertia in the range 10-30 J K-1 m-2 s-12 and probed depths oforder 1-4 cm We here investigate potential spatial variations ofthermal and electrical properties by analysing separately thegeomorphological regions described by Thomas et al (2015) Foreach region we select measurements corresponding to those areasobtained at different local times and effective latitudes We modelthe thermal profiles with depth and the outgoing mm and submmradiation for different values of the thermal inertia and of the ratioof the electrical to the thermal skin depth We will present the bestestimates of thermal inertia and electricthermal depth ratios foreach region selected Additional information on subsurfacetemperature gradients may be inferred by using observations atvarying emergence anglesThe thermal emission from southern regions has been analysed byChoukroun et al (2015) during the polar night Now that the comethas reached perihelion the South Pole is fully illuminatedallowing extension of this study to these regions

Author(s) Cedric Leyrat Doriann Blain EmmanuelLellouch Paul von Allmen Stephen Keihm MatthieuChoukroun Pete Schloerb Nicolas Biver Samuel Gulkis Mark HofstadterInstitution(s) 1 Jet Propulsion Laboratory 2 LESIA -Observatoire de Paris 3 University of Massachusetts

41306 ndash Modeling of the VIRTIS-M Observations ofthe Coma of Comet 67PChuryumov-GerasimenkoThe recent images of the inner coma of 67PChuryumov-Gerasimenko (CG) made by the infrared channel of the VIRTIS-Minstrument on board the Rosetta spacecraft show the gasdistribution as it expands in the coma (Migliorini et al 2015 DPSabstract)Since VIRTIS is a remote sensing instrument a proper modeling ofthese observations requires the computation of the full coma ofcomet CG which necessitates the use of a kinetic approach due tothe rather low gas densities Hence we apply a Direct SimulationMonde Carlo (DSMC) method to solve the Boltzmann equationand describe CGrsquos coma from the nucleus surface up to a fewhundreds of kilometers The model uses the SHAP5 nucleus shapemodel from the OSIRIS team The gas flux distribution takes intoaccount solar illumination including self-shadowing The localactivity at the surface of the nucleus is given by sphericalharmonics expansion reproducing best the ROSINA-DFMS dataThe densities from the DSMC model outputs are then integratedalong the line-of-sight to create synthetic images that are directlycomparable with the VIRTIS-M column density measurementsThe good agreement between the observations and the modelillustrates our continuously improving understanding of thephysics of the coma of comet CGAcknowledgementsWork at UofM was supported by contracts JPL1266313JPL1266314 and NASA grant NNX09AB59G Work at UoB wasfunded by the State of Bern the Swiss National Science Foundationand by the European Space Agency PRODEX Program Work atSouthwest Research institute was supported by subcontract1496541 from the JPL Work at BIRA-IASB was supported by theBelgian Science Policy Office via PRODEXROSINA PEA 90020The authors would like to thank ASI CNES DLR NASA forsupporting this research VIRTIS was built by a consortium formedby Italy France and Germany under the scientific responsibility ofthe IAPS of INAF which guides also the scientific operations Theconsortium includes also the LESIA of the Observatoire de Parisand the Institut fuumlr Planetenforschung of DLR The authors wishto thank the RSGS and the RMOC for their continuous support

Author(s) Nicolas Fougere Michael R Combi ValeriyTenishev Andre Bieler Alessandra Migliorini GiuseppePiccioni Fabrizio Capaccioni Gianrico Filacchione GaborToth Zhenguang Huang Tamas Gombosi Kenneth Hansen Dominique Bockelee-Morvan Vincent Debout StephaneErard Cedric Leyrat Uwe Fink Martin Rubin KathrinAltwegg Chia-Yu Tzou Lena Le Roy Ursina Calmonte Jean-Jacques Berthelier Henri Reme Myrtha Hassig StephenFuselier Bjorn Fiethe Johan De KeyserInstitution(s) 1 Belgian Institute for Space Aeronomy 2Istituto Nazionale di Astrofisica 3 Laboratoire drsquoEtudes Spatialeset drsquoInstrumentation en Astrophysique Observatoire deParisCNRSUniversiteacute Pierre et Marie CurieUniversiteacute Paris-Diderot 4 Southwest Research Institute 5 TU Braunschweig 6Universite de Toulouse 7 University of Arizona 8 University ofBern 9 University of Michigan

41307 ndash Activity and jets of comet 67P as observed byOSIRIS since August 2014Dust jets ie fuzzy collimated streams of cometary material arisingfrom the nucleus have been observed in-situ on all comets sincethe Giotto mission flew by comet 1PHalley in 1986 Yet theirformation mechanism remains unknown Several solutions havebeen proposed from localized physical mechanisms on thesurfacesub-surface to purely dynamical processes involving thefocusing of gas flows by the local topography While the latterseems to be responsible for

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the larger features high resolution imagery has shown that broadstreams are composed of many smaller features (a few meterswide) that connect directly to the nucleus surfaceThe OSIRIS cameras on board Rosetta are monitoring these jets inhigh resolution images since August 2014 We followed this type ofactivity from 36 AU to perihelion (123 AU) We have traced thejets back to their sources on the surface and noticed a goodcorrelation with sub-solar latitude surface morphologies and colorvariations As the comet receives more insolation we observeddifferent type of jets some of them sustained beyond the localsunset and an increasing number of transient events with suddenrelease of gas and dustWe will present here how activity changes with local seasons andhow it contributes to the erosion of the surfaceAcknowledgements OSIRIS was built by a consortium led by theMax-Planck-Institut fuumlr Sonnensystemforschung GoumlttingenGermany in collaboration with CISAS University of Padova Italythe Laboratoire dAstrophysique de Marseille France the Institutode Astrofisica de Andalucia CSIC Granada Spain the ScientificSupport Office of the European Space Agency Noordwijk TheNetherlands the Instituto Nacional de Tecnica AeroespacialMadrid Spain the Universidad Politechnica de Madrid Spain theDepartment of Physics and Astronomy of Uppsala UniversitySweden and the Institut fuumlr Datentechnik undKommunikationsnetze der Technischen Universitaumlt BraunschweigGermany We thank the Rosetta Science Ground Segment at ESACthe Rosetta Mission Operations Centre at ESOC and the RosettaProject at ESTEC for their outstanding work enabling the sciencereturn of the Rosetta Mission

Author(s) Jean-Baptiste Vincent Nilda Oklay MaurizioPajola Sebastian Houmlfner Holger Sierks Cesare Barbieri Philippe Lamy Rafael Rodrigo Hans Rickman DetlefKoschnyInstitution(s) 1 CISAS 2 ESTEC 3 INTA-CSIC 4 LAM 5MPS 6 Uppsala University

41308 ndash Dust Outbursts From Comet67PChuryumov-Gerasimenko Observed byRosetta-AliceThe comet 67PChuryumov-Gerasimenko passed throughperihelion on 13 August 2015 In the weeks surrounding theperihelion passage several dramatic outbursts of dust have beenobserved by instruments aboard ESArsquos Rosetta spacecraft Theseoutbursts are typically intense and short-lived with timescales onthe order of several tens of minutes to a few hours We report onthe two largest of these dusty outbursts observed by the Alicefar-ultraviolet (700-2050Aring) spectrograph which occurred on 10July 2015 and 22 August 2015 On 10 July 2015 0206 UTC Alicespectra of the sunward limb nucleus and anti-sunward limb showtypical levels of dust-scattered sunlight with the sunward limb3-4x brighter than the anti-sunward limb Beginning around 0210UTC the dust on the anti-sunward side of the nucleus brightenedrapidly increasing by a factor of 21 over pre-outburst levels whenintegrated over a 10-minute exposure A 40s exposure beginning at0220 showed an additional factor of two increase in brightnessDuring the outburst the dust became significantly brighter thanthe sunlit nucleus Concurrent NAVCAM images show a large dustcloud expanding out from the night side of the nucleus Despitethis forty-fold increase in dust brightness the Alice data show noevidence of enhancements of H O CO CO O O or H in thepost-outburst spectra By 0424 UTC after a 2-hour data gap thecomet had returned to pre-event levels Although complicated bythe scanning motion of the spacecraft the start of Aliceobservations on 22 August 2015 revealed a major dust outburst inprogress this time confined to the sunward side of the nucleusBetween 0703 and 0754 the brightness of dust on the sunwardside faded by a factor of 7 NAVCAM images from this period alsoshow a dramatic fan-shaped cloud of dust Unlike the 10 Julyevent the 22 August event shows some evidence of increased gasemissions

Author(s) Andrew J Steffl Paul D Feldman Michael FAHearn Jean-Loup Bertaux Lori M Feaga Brian A Keeney Matthew M Knight John Noonan Joel Wm Parker Eric RSchindhelm S Alan Stern Ronald J Vervack Harold AWeaverInstitution(s) 1 Johns Hopkins University 2 Johns HopkinsUniversity Applied Physics Lab 3 LATMOS 4 LowellObservatory 5 Southwest Research Institute 6 Univeristy ofColorado 7 Univeristy of Maryland

41309 ndash Evidence for a precession of the nucleus ofcomet 67PC-G from ROSETTAOSIRIS imagesThe retrieval of the rotational parameters of comet 67PC-G is partof the shape reconstruction process conducted from data collectedby the OSIRIS imaging system aboard ROSETTA Among otherparameters this includes the reconstruction of the (RADec)direction of the Z axis of the body-fixed frame and that of theangular momentum vector The stereophotogrammetric solution(Preusker et al AampA 2015 in press) obtained in Aug-Sep 2014already showed evidence for a complex rotation of comet 67PC-GA subsequent analysis of the rotational data obtained using thestereophotoclinometry method (Gaskell et al MPampS 43 10492008) up to April 2015 also revealed a precession with a likelihoodgreater than 9999 The amplitude and period of the (RADec)variations measured with both methods are fully compatibleWe propose an interpretation of the measured period as acombination of torque free motions a rotation combined with aprecession of small amplitude The modeling of this motion hasimplications on the value of the moments of inertia from which itis possible to constrain the internal density distribution of comet67PC-G

Author(s) Laurent Jorda Pedro Gutierrez BjoernDavidsson Robert Gaskell Stubbe Hviid Horst Uwe Keller Lucie Maquet Stefano Mottola Frank Preusker FrankScholtenInstitution(s) 1 European Space Agency 2 German AerospaceCenter (DLR) 3 Instituto de Astrofisica de Andalucia 4Laboratoire dAstrophysique de Marseille 5 Planetary ScienceInstitute 6 Technical University of Braunschweig 7 University ofUppsala

41310 ndash The interior of 67PC-G nucleus revealed byCONSERT measurements and simulationsThe CONSERT bistatic radar onboard the Rosetta spacecraft andthe Philae lander has begun to reveal the internal structure ofComet 67PChuryumov-Gerasimenko through radio tomographicmapping between the lander and main spacecraft The small lobewas found to be structurally homogeneous at the spatial scale often meters corresponding to a few wavelengths of CONSERTinstrument [1] The real part of the relative permittivity has beenderived from the travel time of the strongest signals obtained on12-13 November 2014 from Philae final landing site Since the finalposition of the lander was not accurately defined numerousray-tracing simulations were performed to constrain theambiguities on Philae position using the known position of Rosettaand the propagation time and paths inside and outside the nucleusA least square statistical analysis between measurements andsimulations lead to deduce a bulk relative permittivity about (127 plusmn01) meanwhile the uncertainty in the lander location was reducedto an area of about 21 by 34 square meters [1]Ongoing theoretical and experimental simulations are providingmore insights on the nucleus properties Numerical ray-tracingsimulations of the propagation at grazing angles have beenperformed for various subsurface permittivity models Theyestablish that a permittivity gradient in the shallow sub-surfacewould have a strong effect on the wave propagation Thepermittivity probably decreases with depth suggesting that asignificant increase of dustice ratio with depth is unlikely [2]Laboratory simulations of the permittivity of subsurface cometaryanalog materials [3] and of surface porous analog samples [4]have taken place Results suggest 67P dielectric properties to bemainly controlled by porosity the dustice volumetric ratio torange from 04 to 26 and the porosity to range from 75 to 85 [1]

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132

Further on-going laboratory measurements will be discussedSupports from CNES and NASA are acknowledged[1] Kofman et al Science 349 6247 aab0639 2015[2] Ciarletti et al AampA (Rosetta issue) in press 2015[3] E Heggy et al Icarus 221 925 2012[4] Brouet et al AampA (Rosetta issue) in press 2015

Author(s) A Levasseur-Regourd Wlodek Kofman AlainHerique Valeacuterie Ciarletti Essam Heggy Jeacutereacutemie LasueInstitution(s) 1 IPAG-CNRS 2 IRAP-OMP CNRS-UPS 3University of Southern California 4 UPMC (Sorbonne Univ) 5UVSQ (UPSay)

41311 ndash 3D reconstruction of the final PHILAE landingsite AbydosThe Abydos region is the region of the final landing site of thePHILAE lander The landing site has been potentially identified onimages of this region acquired by the OSIRIS imaging systemaboard the orbiter before (Oct 22 2014) and after (Dec 6-13 2014)the landing of PHILAE (Lamy et al in prep) Assuming that thisidentification is correct we reconstructed the topography of Abydosin 3D using a method called ``multiresolution photoclinometry bydeformation (MPCD Capanna et al The Visual Computer29(6-8) 825-835 2013) The method works in two steps (a) aDTM of this region is extracted from the global MPCD shapemodel (b) the resulting triangular mesh is progressively deformedat increasing spatial resolution in order to match a set of 14 imagesof Abydos at pixel resolutions between 1 and 8 m The method usedto perform the image matching is the L-BFGS-b non-linearoptimization (Morales et al ACM Trans Math Softw 38(1) 1-42011)In spite of the very unfavourable illumination conditions weachieve a vertical accuracy of about 3 m while the horizontalsampling is 05 m The accuracy is limited by high incidence angleson the images (about 60 deg on average) combined with a complextopography including numerous cliffs and a few overhangs Wealso check the compatibility of the local DTM with the imagesobtained by the CIVA-P instrument aboard PHILAE If the Lamy etal identification is correct our DTM shows that PHILAE landed ina cavity at the bottom of a small cliff of 8 m height

Author(s) Claire Capanna Laurent Jorda Philippe Lamy Gilles Gesquiegravere Ceacutedric Delmas Joeumllle Durand PhilippeGaudon Eric JuradoInstitution(s) 1 CNES 2 Laboratoire dAstrophysique deMarseille 3 LIRIS

41312 ndash Report on the ground-based observationcampaign of 67PChuryumov-GerasimenkoRosetta gets closer to the nucleus than any previous mission andreturns wonderfully detailed measurements from the heart of thecomet but at the cost of not seeing the large scale coma and tailsThe ground-based campaign fills in the missing part of the picturestudying the comet at about 1000 km resolution and followinghow the overall activity of the comet varies These data providecontext information for Rosetta so changes in the inner coma seenby the spacecraft can be correlated with the phenomena observablein comets This will not only help to complete our understanding ofthe activity of 67P but also to allow us to compare it with othercomets that are only observed from the groundThe ground-based campaign includes observations with nearly allmajor facilities world-wide In 2014 the majority of data came fromthe ESO VLT as the comet was still relatively faint and in Southernskies but as it returns to visibility from Earth in 2015 it isconsiderably brighter approaching its perihelion in August and atNorthern declinations I will present results from the 2014campaign including visible wavelength photometry andspectroscopy and the latest results from 2015 observations

Author(s) Emmanuel JehinInstitution(s) 1 Universiteacute de Liegravege

41313 ndash Hubble Space Telescope Imaging Polarimetryof Comet 67PChuryumov-Gerasimenko Obtained

During the Rosetta MissionWe present pre- and post-perihelion high-spatial resolution (005arcsecpixel) 06 micron imaging polarimetry of Comet67PChuryumov-Gerasimenko taken with the Advanced Camerafor Surveys aboard the Hubble Space Telescope (HST) Thepre-perihelion observations were obtained at two epochs chosen tobracket the times when the closest orbits of Rosetta were flown(down to 10 km for extended periods 2014-Aug-19 r = 352 au Δ= 276 au α asymp 120˚) and the Philae landing took place (2014-Nov-17 r = 296 au Δ = 343 au α asymp 157˚) Our preliminaryanalyses of both pre-perihelion epochs shows that the polarizationposition angle lies in the scattering plane thus is negative with adegree of polarization p asymp -2 The two post-perihelion epochswere matched to the first time after perihelion that the comet wasobservable with HST (2015-Oct-10 r = 143 au Δ = 180 au α asymp335˚) and when the comet was again viewed at small phase angle(2016-Feb-19 r = 240 au Δ = 149 au α asymp 120˚) We discuss ourpolarimetry results in context with in situ measurements of dustparticles obtained with the Rosetta spacecraft

Author(s) Dean C Hines Anny-Chantal Levasseur-Regourd Edith Hadamcik Vadym Kaydash Matthew M Knight

Ludmilla Kolokolova Jian-Yang Li Carey M Lisse KarriMuinonen Max Mutchler Yuriy Shkuratov ColinSnodgrass Michael L Sitko Matt G G T Taylor GordenVideen Padmavati A Yanamandra-Fisher Evgenij ZubkoInstitution(s) 1 Applied Physics Laboratory 2 ESA ESTEC 3Kharkov National University 4 Lowell Observatory 5 MPI forSolar System Research 6 Planetary Science Institute 7 SpaceScience Institute 8 Space Telescope Science Institute 9 Universityof Helsinki 10 University of Helsinki 11 University of Maryland12 UPMC (Sorbonne Univ) 13 UPMC LATMOS

41314 ndash Water production rates of recent comets(2015) by SOHOSWAN and the SOHOSWAN surveyThe all-sky hydrogen Lyman-alpha camera SWAN (Solar WindAnisotropies) on the SOlar and Heliospheric Observatory (SOHO)satellite makes observations of the hydrogen coma of comets Mostwater molecules produced by comets are ultimatelyphotodissociated into two H atoms and one O atom producing ahuge atomic hydrogen coma that is routinely observed in the dailyfull-sky SWAN images in comets of sufficient brightness Waterproduction rates are calculated using our time-resolved model(Maumlkinen amp Combi 2005 Icarus 177 217) typically yielding about1 observation every 2 days on the average for each comet Here wedescribe the progress in analysis of observations of cometsobserved in 2015 and those selected from the archive for analysisThese include comets C2013 US10 (Catalina) C2014 Q1(PanSTARRS) and possibly 67PChuryumov-Gerasimenko Astatus update on the entire SOHOSWAN archive of waterproduction rates in comets will also be given SOHO is aninternational cooperative mission between ESA and NASA Supportfrom grants NNX11AH50G from the NASA Planetary AstronomyProgram and NNX13AQ66G from the NASA Planetary MissionData Analysis Program are gratefully acknowledged as is supportfrom CNRS CNES and the Finnish Meteorological Institute(FMI)

Author(s) Michael R Combi J T T Maumlkinen Jean-LoupBertaux Eric Queacutemerais Steacutephane FerronInstitution(s) 1 ACRI-st 2 Finnish Meteorologoical Institute3 LATMOSIPSI Universiteacute de Versailles Saint-Quentin 4 Univof Michigan

41315 ndash The primordial nucleus of Comet67PChuryumov-GerasimenkoObservations of Comet 67PChuryumov-Gerasimenko by Rosettashow that the nucleus is bi-lobed extensively layered has a lowbulk density a high dust-to-ice mass ratio (implying high porosity)and weak strength except for a thin sintered surface layer Thecomet is rich in supervolatiles (CO CO2 N2) may containamorphous water ice and displays little to no signs of aqueousalteration Lack of phyllosilicates in Stardust samples from Comet81PWild 2 provides further support that comet nuclei did not

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contain liquid waterThese properties differ from those expected for 50-200 kmdiameter bodies in the primordial disk We find that thermalprocessing due to Al-26 combined with collisional compactioncreates a population of medium-sized bodies that are comparablydense compacted strong heavily depleted in supervolatilescontaining little to no amorphous water ice and that haveexperienced extensive aqueous alteration Irregular satellitesPhoebe and Himalia are potential representatives of thispopulation Collisional rubble piles inherit these properties fromtheir parents We therefore conclude that observed comet nucleiare primordial rubble piles and not collisional rubble pilesWe propose a concurrent comet and TNO formation scenario thatis consistent with these observations We argue that TNOs formdue to streaming instabilities at sizes of about 50-400 km and thatabout 350 of these grow slowly in a low-mass primordial disk to thesize of Triton causing little viscous stirring during growth Wepropose a dynamically cold primordial disk that preventsmedium-sized TNOs from breaking into collisional rubble pilesand allows for the survival of primordial rubble-pile comets Weargue that comets form by hierarchical agglomeration out ofmaterial that remains after TNO formation This slow growth isnecessary to avoid thermal processing by Al-26 and to allow cometnuclei to incorporate 3 Myr old material from the inner SolarSystem found in Stardust samples Growth in the Solar Nebulacreates porous single-lobe nuclei while continued growth in amildly viscously stirred primordial disk creates denser outer layersand allow bi-lobe nucleus formation through mergers

Author(s) Bjorn Davidsson Holger Sierks CarstenGuettler Francesco Marzari Maurizio Pajola HansRickman Michael AHearn Anne-Therese Auger MohamedEl-Maarry Sonia Fornasier Pedro Gutierrez Horst UweKeller Matteo Massironi Colin Snodgrass Jean-BaptisteVincent Cesare Barbieri Philippe Lamy Rafael Rodrigo Detlef Koschny Antonella Barucci Jean-Loup Bertaux Ivano Bertini Gabriele Cremonese Vania Da Deppo StefanoDebei Mariolino De Cecco Clement Feller Marco Fulle Olivier Groussin Stubbe Hviid Sebastian Hoefner Wing-Huen Ip Laurent Jorda Joerg Knollenberg GaborKovacs Joerg-Rainer Kramm Ekkehard Kuehrt MichaelKueppers Fiorangela La Forgia Luisa Lara MonicaLazzarin Jose Lopez Moreno Richard Moissl-Fraund Stefano Mottola Giampiero Naletto Nilda Oklay NicolasThomas Cecilia TubianaInstitution(s) 1 Aix Marseille Universite CNRS LAM(Laboratoire dAstrophysique de Marseille) 2 Centro deAstrobiologia CSIC-INTA 3 Centro di Ateneo di Studi ed AttivitaSpaziali Giuseppe Colombo (CISAS) University of Padova 4CNR-IFN UOS Padova LUXOR 5 Department of IndustrialEngineering ndash University of Padova 6 Deutsches Zentrum fuerLuft- und Raumfahrt (DLR) 7 INAF - Osservatorio Astronomico8 INAF Osservatorio Astronomico di Padova VicolodellOsservatorio 9 Institut fuer Geophysik und extraterrestrischePhysik (IGEP) Technische Universitaet Braunschweig 10Instituto de Astrofisica de Andalucia (CSIC) 11 LaboratoiredrsquoAstrophysique de Marseille 12 LATMOS CNRSUVSQIPSL 13LESIA-Observatoire de Paris CNRS Universite Pierre et MarieCurie Universite Paris Diderot 14 Max-Planck-Institut fuerSonnensystemforschung 15 National Central UniversityGraduate Institute of Astronomy 16 Operations DepartmentEuropean Space Astronomy CentreESA 17 PAN Space ResearchCenter 18 Physikalisches Institut der Universitaet Bern 19Planetary and Space Sciences Department of Physical SciencesThe Open University 20 Scientific Support Office European SpaceResearch and Technology CentreESA 21 University of MarylandDepartment of Astronomy 22 University of Padova Departmentof Information Engineering 23 University of PadovaDepartment of Physics and Astronomy 24 University of PadovaDepartment of Physics and Astronomy Vicolo dellOsservatorio25 University of Trento 26 University of Uppsala Dept ofPhysics and Astronomy

41316 ndash Comet 67P observations with LOTUS a newnear-UV spectrograph for the Liverpool Telescope

The European Space Agencyrsquos Rosetta spacecraft has been orbitingcomet 67PChuryumov-Gerasimenko (hereinafter ldquo67Prdquo) sinceAugust 2014 providing in-situ measurements of the dust gas andplasma content of the coma within ~100km of the nucleusSupporting the mission is a world-wide coordinated campaign ofsimultaneous ground-based observations of 67P (wwwrosetta-campaignnet) providing wider context of the outer coma and tailinvisible to Rosetta We can now compare these observationsaugmented by ground truth from Rosetta with those of othercomets past and future that are only observed from EarthThe robotic Liverpool Telescope (LT) is part of this campaign dueto its unique ability to flexibly and autonomously schedule regularobservations over entire semesters Its optical imagery has recentlybeen supplemented by near-UV spectroscopy to observe the UVmolecular bands below 4000Aring that are of considerable interest tocometary science The LTs existing spectrographs FRODOSpec andSPRAT cut off at 4000Aring so the Liverpool Telescope Optical-to-UVSpectrograph - LOTUS - was fast-track designed built anddeployed on-sky in just five months LOTUS contains no movingparts acquisition is made with the LTs IOO imaging camera anddifferent width slits for calibration and science are selected byfine-tuning the telescopes pointing on an innovative step designin its single slitWe present here details of the LOTUS spectrograph and somepreliminary results of our ongoing observations of comet 67P

Author(s) Jon Marchant Helen Jermak Iain Steele ColinSnodgrass Alan Fitzsimmons Geraint JonesInstitution(s) 1 Liverpool John Moores University 2 QueensUniversity Belfast 3 The Open University 4 University CollegeLondon

414 ndash Active Asteroids41402 ndash The Reactivation of Main-Belt Comet 324PLaSagra (P2010 R2)We present observations using the Baade Magellan and Canada-France-Hawaii telescopes showing that main-belt comet 324PLaSagra formerly known as P2010 R2 has become active again forthe first time since originally observed to be active in 2010-2011The object appears point-source-like in March and April 2015 as itapproached perihelion (true anomaly of ν~300 deg) but was ~1mag brighter than expected if inactive suggesting the presence ofunresolved dust emission Activity was confirmed by observationsof a cometary dust tail in May and June 2015 We find an apparentnet dust production rate of lt01 kgs during these observations324P is now the fourth main-belt comet confirmed to berecurrently active a strong indication that its activity is driven bysublimation It now has the largest confirmed active range of alllikely main-belt comets and also the most distant confirmedinbound activation point at R~28 AU Further observations duringthe current active period will allow direct comparisons of activitystrength with 324Prsquos 2010 activity

Author(s) Henry H Hsieh Scott SheppardInstitution(s) 1 Carnegie Institution for Science 2 PlanetaryScience Institute

41403 ndash Evidence for an Impact Event on (493)GriseldisAn extended feature associated with the main-belt asteroid (493)Griseldis has been detected in three R-band exposures of 330 to350 sec duration spanning 5 hours taken on 2015 Mar 17 UT withthe HyperSuprimeCam instrument on the 8-m Subaru telescopeAdditional observations of Griseldis were taken with the 65-mMagellan telescope on 2015 Mar 21 UT and the extended featurewas still detected though weaker No extended feature wasdetected in one unfiltered 600 sec exposure taken with the 22-mUniversity of Hawaii telescope on 2015 Mar 24 UT or in Magellanimages taken on 2015 Apr 18 and May 21 UT Griseldis is a 46 kmdiameter P-type asteroid with semimajor axis of 312 AUeccentricity of 017 inclination of 15 deg and Tisserand parameterof 3187 relative to Jupiter The heliocentric distance on 2015 Mar

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17 was 333 AU thus the asteroid was closer to aphelion than it wasto perihelion The most recent perihelion passage was on 2013 Aug17 and the orbital period is 55 years Additional images in theSubaru and CTIO DECam archives from 2010 and 2012respectively show no signs of activity The position angle of theextended feature does not match either the antisolar direction orthe negative velocity vector of the asteroid The rotationallightcurve of Griseldis is known to show a peak-to-peak amplitudeof up to 045 mag over a 52-hour period No anomalousbrightening of the asteroid is evident in the 2015 photometryreported along with the astrometry of this object The observationsare consistent with the occurrence of an impact event on thisasteroid Additional analysis of the images is in progress

Author(s) David J Tholen Scott S Sheppard Chad ATrujilloInstitution(s) 1 Carnegie Inst 2 Gemini Obs 3 Univ ofHawaii

41404 ndash Thermal alteration in carbonaceouschondrites and implications for sublimation in rockcometsRock comets are small solar system bodies in Sun-skirting orbits(perihelion q lt ~015 AU) that form comae rich in mineralsublimation products but lack typical cometary ice sublimationproducts (H2O CO2 etc) B-class asteroid (3200) Phaethonconsidered to be the parent body of the Geminid meteor shower isthe only rock comet currently known to periodically eject dust andform a coma Thermal fracturing or thermal decomposition ofsurface materials may be driving Phaethonrsquos cometary activity (Li ampJewitt 2013) Phaethon-like asteroids have dynamically unstableorbits and their perihelia can change rapidly over their ~10 Myrlifetimes (de Leoacuten et al 2010) raising the possibility that otherasteroids may have been rock comets in the past Here we proposeusing spectroscopic observations of mercury (Hg) as a tracer of anasteroidrsquos thermal metamorphic history and therefore as aconstraint on its minimum achieved perihelion distanceB-class asteroids such as Phaethon have an initial compositionsimilar to aqueously altered primitive meteorites such as CI- orCM-type meteorites (Clark et al 2010) Laboratory heatingexperiments of ~mm sized samples of carbonaceous chondritemeteorites from 300K to 1200K at a rate of 15Kminute showmobilization and volatilization of various labile elements attemperatures that could be reached by Mercury-crossing asteroidsSamples became rapidly depleted in labile elements and inparticular lost ~75 of their Hg content when heated from~500-700 K which corresponds to heliocentric distances of~015-03 au consistent with our thermal models Mercury hasstrong emission lines in the UV (~ 185 nm) and thus its presence(or absence) relative to carbonaceous chondrite abundances wouldindicate if these bodies had perihelia in their dynamical historiesinside of 015 AU and therefore may have previously beenPhaethon-like rock comets Future space telescopes orballoon-borne observing platforms equipped with a UVspectrometer could potentially detect the presence or absence ofstrong ultraviolet mercury lines on rock comets or rock cometcandidates

Author(s) Alessondra Springmann Dante S Lauretta Jordan K SteckloffInstitution(s) 1 Purdue University 2 University of Arizona

415 ndash Comets Physical CharacteristicsDynamics and Composition41501 ndash Sizing Up the Comets The NEOWISE MissionSurvey of Cometary NucleiiThe NEOWISE mission has provided the largest cometary surveyin the infrared The NEOWISE mission was originally anaugmentation to detect solar system objects and specifically NearEarth Objects using the Wide-Field Infrared Survey Explorer(WISE) spacecraft Funded by NASAs Planetary Division throughthe Near-Earth Object Observation program NEOWISE detected

moving objects throughout the WISE mission[1-2] after which thespacecraft was placed in a state of hybernation After 32 monthsthe re-christened NEOWISE spacecraft was returned to a zenith-pointing orbit On December 23 2013 the reactivated surveybegan[3]While NEOWISEs primary purpose was the detection of NEOs atotal of 163 comets have been identified in the prime survey(January 7 2010 - Febraury 1 2011) and over 75 have beenobserved during the NEOWISE reactivate mission to date Theseobservations have been made at multiple epochs often when thecomets were at large heliocentric distances or exhibited little or noactivity Preliminary analysis of the 25 NEOWISE-discoveredcomets has indicated possible differences between the sizedistributions of long-period comets (LPCs) and short-periodcomets (SPCs) in their raw (not de-biased) samples[4] On averagethe observed LPCs were larger than the SPCs We will discuss theresults of the analysis of the larger sample of more than 65 nucleiiextracted from the prime mission data as well as the reactivatedmission sampleThis publication makes use of data products from the Wide-fieldInfrared Survey Explorer which is a joint project of the Universityof California Los Angeles and the Jet PropulsionLaboratoryCalifornia Institute of Technology funded by theNational Aeronautics and Space Administration as well as dataproducts from NEOWISE which is a project of JPLCaltechfunded by the Planetary Science Division of NASA RS SS and EKwere supported by the NASA Postdoctoral Program[1] Cutri et al 2013 (httpwise2ipaccaltechedudocsreleaseallskyexpsupindexhtml)[2] Mainzer et al 2011 ApJ 731 53[3] Mainzer et al 2014 ApJ 792 30[4] Bauer J M et al 2015The NEOWISE-Discovered CometPopulation and the CO+CO2 production rates ApJ Submitted

Author(s) James M Bauer Tommy Grav A K Mainzer Emily Kramer Rachel A Stevenson Yanga R Fernaacutendez Joseph R Masiero Carolyn R Nugent Roc M Cutri SarahSonnett Frank J Masci Karen J Meech Russel Walker Carey M Lisse Paul R Weissman John W Dailey NathanBlair Andrew Lucas Robert S McMillan Edward L WrightInstitution(s) 1 Applied Physics Laboratory Johns HopkinsUniversity 2 Department of Astronomy University of California3 Infrared Analysis and Processing Center (IPAC) CaliforniaInstitute of Technology 4 Institute for Astronomy University ofHawaii 5 Jet Propulsion Lab 6 Lunar and PlanetaryLaboratory University of Arizona 7 Monterey Institute forResearch in Astronomy 8 Planetary Science Institute 9University of Central Florida

41502 ndash Investigating the Effects of Temperature onthe Signatures of Shocks Propagated Through Impactsinto Minerals Found in Comets and AsteroidsComets and asteroids are subjected to extremely cold conditionsthroughout their lifetimes During their sojourns in the solarsystem they are subjected to collisions at speeds that are easilycapable of generating shock waves in their constituent materials Inaddition to ices more common silicate minerals such as olivinesand pyroxenes are important components of these objects Thecollision-induced shocks could affect the spectral signatures ofthose mineral components which could in turn be detectedtelescopically We have embarked on a project to determine howimpact-generated shock might affect the reflectance spectra andstructures of select silicates as both impact speed and targettemperature are varied systematicallyWhile the effects of impact speed (in the form of shock stress) onnumerous materials have been and continue to be studied the roleof target temperature has received comparatively little attentionpresumably because of the operational difficulties it can introduceto experimentation Our experiments were performed with thevertical gun in the Experimental Impact Laboratory of the JohnsonSpace Center A liquid-nitrogen system was plumbed to permitcooling of the target container and its contents under vacuum totemperatures as low as -100degC (173 K) Temperatures weremonitored by thermocouples mounted on the outside of the target

3 12

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container Because those sensors were not in contact with thetarget material at impact the measured temperatures are treated aslower limits for the actual values Peridot (Mg-rich olivine) andenstatite (Mg-rich orthopyroxene) were used as targets whichinvolved the impact of alumina (Al O ) spheres at speeds of 20 ndash27 km s and temperatures covering 25degC to -100degC (298 K to 173K) We have begun collecting and analyzing data in the near tomid-IR with a Fourier-transform infrared spectrometer andpreliminary analyses show that notable differences inabsorption-band strength and position occur as functions of bothimpact speed (peak shock stress) and initial temperatureFunding was provided by the NASA PGampG grant 09-PGG09-0115NSF grant AST-1010012 Special thanks to the NASA EIL staff FCardenas and R Montes

Author(s) Susan M Lederer Elizabeth A Jensen MichaelFane Douglas C Smith Jacob Holmes Lindsay P Keller SeanS Lindsay Diane H Wooden Mark J Cintala Michael EZolenskyInstitution(s) 1 Cal State Univ SB 2 NASA Ames ResearchCenter 3 NASA Johnson Space Center 4 Planetary ScienceInstitute 5 Univ of Oxford

41503 ndash High precision comet trajectory estimatesthe Mars flyby of C2013 A1 (Siding Spring)The Mars flyby of C2013 A1 (Siding Spring) represented a uniqueopportunity for imaging a long-period comet and resolving itsnucleus and rotation period Because of the small encounterdistance and the high relative velocity the goal of successfullyobserving C2013 A1 from the Mars orbiting spacecrafts posedstrict requirements on the accuracy of the comet ephemerisestimate These requirements were hard to meet as comets areknown for being highly unpredictable astrometric observationscan be significantly biased and nongravitational perturbationssignificantly affect the trajectory Therefore we remeasured acouple of hundred astrometric positions from images provided byground-based observers and also observed the comet with the MarsReconnaissance Orbiterrsquos HiRISE camera on 2014 October 7 Inparticular the HiRISE observations were decisive in securing thetrajectory and revealed that nongravitational perturbations werelarger than anticipated The comet was successfully observed andthe analysis of the science data is still ongoing By adding somepost-encounter data and using the Rotating Jet Model fornongravitational accelerations we constrain the rotation pole ofC2013 A1

Author(s) Davide Farnocchia Steven R Chesley MarcoMicheli Alan Delamere Rodney S Heyd David J Tholen JonD Giorgini William M Owen Leslie K TamppariInstitution(s) 1 Delamere Support Services 2 ESA NEOCoordination Center 3 Institute for Astronomy University ofHawaii 4 Jet Propulsion Laboratory California Institute ofTechnology 5 Planetary Image Research Laboratory Lunar andPlanetary Laboratory University of Arizona

41504 ndash The Resolved Nucleus and Coma of CometSiding Spring from MRO ObservationsComet Siding Spring (C2013 A1) is a dynamically new cometdiscovered on January 4 2013 On October 19 2014 just 6 dayspefore perihelion Siding Spring made an historic close approach(CA) to Mars closing to a distance of only 140500 km We usedthe HiRISE camera on the Mars Reconaissance Orbiter to observethe comet from October 17-20 (CA-60 hr to CA+15 hrs) obtaining122 images primarily in broadband filters centered near 500 (BG)and 700 (RED) nm with another filter near 900 (IR) nm addednear close approach The HiRISE pixel scale in these observationsis as small as 138 mpix essentially making this event a fortuitousnatural flyby of a dynamically new cometEnhancement of the closest approach images using both anunsharp mask and a coma fitting and subtraction routine reveals asharply-defined crescent that changes its appearance as the viewinggeometry varies during the comets passage The crescent is likelythe illuminated limb of the nucleus making this the first occasionon which the nucleus of a dynamically new comet has been

resolved Preliminary analyses indicate that the nucleus iselongated (prolate ellipsoid) with a length on the order of akilometerPhotometric measurements of the coma in a constant 48-kmradius aperture show brightness variations in the RED filtersequence with a periodicity of 81 hr Because this is a measure ofdust production the single-peaked lightcurve represents therotation period of the nucleus During the observations oneprimary fan feature is seen in the coma The lightcurve variationswith amplitude of ~40 (60-140) of the average brightness in the48 km aperture correlate to the feature visibility indicating thatthe jet that produces it is the primary source of activity The shapeand direction of the fan suggests that the source is near a poleproducing a cone of dust around the spin axis We anticipate thatthe long time baseline and wide range of viewpoints covered in theMRO images will be useful in computing an independent poleorientation

Author(s) Tony L Farnham W Alan Delamere MichaelSP Kelley Rodney Heyd Jian-Yang LiInstitution(s) 1 Delamere Support Services 2 Lunar andPlanetary Laboratory 3 Planetary Science Institute 4 Univ ofMaryland

41505 ndash Comparing CN Features in Two Comets1PHalley and 103PHartley 2Comets 1PHalley and 103PHartley 2 show distinct CN features intheir respecive comae Both comets are non-principal-axis rotators1PHalley is the proto-type for Halley-type comets with the OortCloud as its possible source region whereas 103PHartley 2 is aJupiter-Family comet that possibly originated from the Kuiper BeltBoth comets were spacecraft targets and studied widely from bothspace and from the groundWe will discuss the properties of CN features and in particular thebehavior of the derived outflow velocities based on the CN featurespresent in the groundbased coma images of these two comets Thecorresponding heliocentric distances for CN images of comet1PHalley range from approximately 08 AU to 20 AU (during itspost-perihelion leg of the 1986 apparition) For CN images ofcomet 103PHartley 2 the corresponding heliocentric distancesrange from 131 AU through the perihelion (at 106 AU) to 125 AU(during its 2010 apparition)Ultimately these results will be used to understand the rotationalstates and the activity behaviors of these two comets

Author(s) Nalin H Samarasinha Cassandra Lejoly JoseBarrera Beatrice Mueller David SchleicherInstitution(s) 1 Lowell Observatory 2 Planetary ScienceInstitute

41506 ndash Rotational Spin-up Caused CO Outgassingon Comet 103PHartley 2The Deep Impact spacecraftrsquos flyby of comet 103PHartley 2 onNovember 4 2010 revealed its nucleus to be a small bilobate andhighly active world [1] [2] The bulk of this activity is driven by COsublimation which is enigmatically restricted to the tip of the smalllobe [1] Because Hartley 2s CO production responds to thediurnal cycle of the nucleus [1] CO ice must be no deeper than afew centimeters below the surface of the small lobe However thehigh volatility of CO would suggest that its sublimation frontshould recede deep below the surface such that diurnal volatileproduction is dominated by more refractory species such as waterice as was observed at comet Tempel 1 [3]Here we show that both the near surface CO ice and its geographicrestriction to the tip of the small lobe suggest that Hartley 2recently experienced an episode of fast rotation We use theGRAVMAP code to compute the stability of slopes on the surface ofHartley 2 as a function of spin period We determine that thesurface of the active region of Hartley 2rsquos small lobe becomesunstable at a rotation period of ~10-12 hours (as opposed to itscurrent spin period of ~ 18 hours [1]) and will flow toward the tipof the lobe excavating buried CO ice and activating CO -drivenactivity However the rest of the surface of the nucleus is stable atthese spin rates and will therefore not exhibit CO activity We

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additionally use Finite Element Model (FEM) analysis todemonstrate that the interior of Hartley 2rsquos nucleus is structurallystable (assuming a cohesive strength of at least 5 Pa) at these spinratesThe uncommonly high angular acceleration of Hartley 2 which haschanged the nucleus spin period by two hours in three months [4]suggests that this episode of fast rotation may have existed only afew years or decades ago Thus Hartley 2 may provide an excellentcase study into the reactivation of quiescent comet nuclei viarotational spin up as would result from weak homogeneous gasemissions via the SYORP EffectReferences [1] AHearn et al Science 332 1396 (2011) [2] Thomaset al Icarus 222 550 (2013) [3] Feaga et al Icarus 190 345 (2007)[4] Samarasinha amp Mueller Ap J 775L10 (2013)

Author(s) Jordan Steckloff Kevin Graves MasatoshiHirabayashi James RichardsonInstitution(s) 1 Arecibo Observatory 2 Purdue University 3University of Colorado

41507 ndash The Distribution of Geometric Albedos ofJupiter-Family Comets From SEPPCoN and Visible-Wavelength PhotometryWe present a preliminary estimate of the distribution of geometricalbedos among the Jupiter-family comet (JFC) population Whilean assumption of 4 is common and consistent with theheretofore limited number of known cometary albedos the trueaverage albedo and albedo spread have not been well constrainedBy knowing a statistically-significant number of albedos and thusthe distribution of albedo values across the comet population wecan investigate overarching science questions about the evolutionof cometary surfaces Our current work makes use of and builds onthe results of the Survey of Ensemble Physical Properties ofCometary Nuclei (SEPPCoN) in which we obtained new andindependent estimates of the radii of 89 JFCs [12] By using thethus-known radius and photometry of a bare nucleus we canconstrain its geometric albedo We will present our preliminaryalbedo estimates for ~50 JFC nuclei and we will discuss theimplications of the ensemble of the results These JFCs were allobserved in R-band and were all observed at relatively largeheliocentric distances (usually gt4 AU from the Sun) where thecomets appeared inactive thus minimizing coma contaminationWe acknowledge the support of NASA grant NNX09AB44G of NSFgrant AST-0808004 and of the Astrophysical ResearchConsortiumApache Point Observatory for this work References[1] Y R Fernandez et al 2013 Icarus 226 1138 [2] M S Kelley etal 2013 Icarus 225 475

Author(s) Yanga R Fernandez Harold Weaver CareyLisse Karen Meech Stephen Lowry James Bauer AlanFitzsimmons Colin SnodgrassInstitution(s) 1 CaltechJPL 2 JHU APL 3 Open Univ 4Queens Univ Belfast 5 UH-IfA 6 Univ Kent 7 Univ of CentralFlorida

41508 ndash The physical properties of water ice incomets a comparative studyDetections of water ice in comets are notably scarce (~10 comets)and our knowledge of cometary ice remains poor As such we arenot able to consider water-ice characteristics in the evaluation ofcomet nuclei formation scenarios despite water ice being the majorcomponent of comets To overcome this deficiency we have beguna systematic low-resolution near-infrared spectroscopic survey tolook for and characterize water-ice grain halos in cometary comaeThe ultimate goal is to survey a large sample of Jupiter-family andOort cloud comets to understand the conditions that favor thedetectability of a comets water-ice grain halo and the factors ifany that may control the observed water-ice properties We reporton the modeling approach to determine the relative abundances ofthe major components within the coma their grain sizes and thetype of mixing (mixed within the coma or mixed within eachaggregate) We present results on a selected set of comets that wereobserved prior and during our survey

Author(s) Silvia Protopapa Michael SP Kelley Bin Yang Jacqueline Keane Jessica Sunshine Michael F AHearn Ludmilla KolokolovaInstitution(s) 1 European Southern Observatory 2 Universityof Hawaii 3 University of Maryland

41509 ndash Volatile Composition of Comet C2012 K1(PanSTARRS)On 2014 May 22 and 24 we characterized the volatile compositionof the dynamically new Oort Cloud comet C2012 K1 (PanSTARRS)using the long-slit high resolution (λΔλ asymp 25000) infared echellespectrograph (NIRSPEC) at the 10m Keck 2 telescope onMaunakea HI We detected fluorescent emission from six primaryspecies (H O HCN CH C H CH OH and CO) and promptemission from one product species (OH - a directory proxy for H-

O) Upper limits were derived for C H and H CO We reportrotational temperatures production rates and mixing ratios(relative to water) Based on the inventory of comets characterizedto date mixing ratios of trace gases in C2012 K1 (PanSTARRS) areabout normal ndash CH OH and C H are slightly enriched CO CH HCN and H CO are average and C H is depleted I will discussC2012 K1 (PanSTARRS) in the context of an emerging taxonomyfor comets based on volatile compositionThis work is supported through the NASA Missouri Space GrantConsortium and the National Science Foundation (NSF 1211362)the NASA Astrobiology Institute through a grant to the GoddardCenter for Astrobiology (81107302120391) and the NASAPlanetary Astronomy Program (81107302030343)

Author(s) Nathan Roth Erika Gibb Boncho P Bonev Michael A DiSanti Geronimo L Villanueva Lucas Paganini Michael J MummaInstitution(s) 1 Catholic University of America 2 NASAGoddard Space Flight Center 3 University of Missouri - St Louis

41510 ndash The Volatile Composition of Comet C2013 V5(Oukaimeden) from Infrared SpectroscopyWe obtained high-quality pre-perihelion spectra of long-periodcomet C2013 V5 (Oukaimeden) on 2014 September 5 and 6 (R =078 AU) with NIRSPEC at Keck 2 and on September 13 (R =050 AU) with CSHELL at the NASA-IRTF Our observationstargeted nine primary volatiles (ie native ices) H2O CO H2COCH3OH HCN NH3 C2H2 CH4 C2H6 Comparison ofabundance ratios for trace volatiles relative to H2O with thosemeasured for other comets reveals an overall depleted chemistry inOukaimedenWe gratefully acknowledge support from NASA PlanetaryAtmospheres Planetary Astronomy and Astrobiology programsand NSF Astronomy and Astrophysics Research Grants

Author(s) Michael A DiSanti Boncho P Bonev Erika LGibb Nathan X Roth Geronimo L Villanueva LucasPaganini Michael J MummaInstitution(s) 1 CUA 2 NASAs GSFC 3 University ofMissouri-St Louis

41511 ndash The favorable apparition of comet C2014 Q2(Lovejoy) and unique insights from ground-based IRobservationsIn February 2015 we observed comet C2014 Q2 (Lovejoy) on twoconsecutive nights using NIRSPEC at the Keck Observatory inHawaii Comet Q2 underwent strong activity and a favorableapparition which triggered astronomical observing campaignsworldwide and yielded unique scientific results over a range ofwavelength regimes From the infrared (IR) observations weretrieve production rates temperatures cosmogonic parametersand abundances of native species (ie volatiles released directlyfrom the nucleus) that are of unique importance in theinterpretation of global properties and highly complementary tomeasurements performed at other wavelengths both of native andproduct species in the coma Our measurements show detection ofseveral molecules we typically detect in the IR and strongunidentified lines We also performed a deep search for HDOemission lines yielding constraints of the DH ratio We will

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discuss our preliminary results in the context of complementarystudies of C2014 Q2 and compare the measured abundances withthose in other comets

Author(s) Lucas Paganini Michael J Mumma Erika LGibb Michael A DiSanti Stefanie N Milam Boncho PBonev Martin A Cordiner Steven Charnley Sara Faggi Geronimo L VillanuevaInstitution(s) 1 INAF - Osservatorio Astrofisico di Arcetri 2NASA Goddard Space Flight Center 3 University of Missouri StLouis

41512 ndash Outgassing and chemical evolution of C2012S1 (ISON)Volatile production rates relative abundances rotationaltemperatures and spatial distributions in the coma were measuredin C2012 S1 (ISON) using long-slit high-dispersion (λΔλ ~25000) infrared spectroscopy as part of a worldwide observingcampaign Spectra were obtained on UT 2013 October 26 and 28with NIRSPEC at the W M Keck Observatory and UT 2013November 19 and 20 with CSHELL at the NASA IRTF H O wasdetected on all dates with production rates increasing by about afactor of 40 between October 26 (R = 112 AU) and November 20(R = 043 AU) Short-term variability of H O was also seen as theproduction rate increased by nearly a factor of two duringobservations obtained over a period of about six hours onNovember 19 C H CH OH and CH abundances were slightlydepleted relative to H O in ISON compared to mean values forcomets measured at infrared wavelengths On the November datesC H HCN and OCS abundances relative to H O appear to beclose to the range of mean values whereas H CO and NH weresignificantly enhanced We will compare derived chemicalabundances in ISON to other comets measured with infraredspectroscopy

Author(s) Neil Dello Russo Ronald J Vervack HideyoKawakita Anita Cochran Adam J McKay Walter M Harris Harold A Weaver Carey M Lisse Michael A DiSanti HitomiKobayashi Nicolas Biver Dominique Bockeleacutee-Morvan Jacques Crovisier Cyrielle Opitom Emmanuel JehinInstitution(s) 1 JHU-APL 2 Koyama AstronomicalObservatory Kyoto Sangyo University 3 LESIA Observatoire deParis 4 Lunar and Planetary Laboratory University of Arizona5 McDonald Observatory 6 NASA-GSFC 7 Universiteacute de Liegravege

41513 ndash Coma in Comet C2012 S1 (ISON) at ~4 auWe analyze HST observations of Comet ISON (C2012 S1) atheliocentric distance ~4 au and phase angle ~12ndash14 degree Theinner coma (lt 5000 km) reveals two polarimetric features positivedegree of linear polarization P = (248 plusmn 045) at projecteddistances less than 236 km and negative polarization P = ndash (16 plusmn045) at 1000 ndash 5000 km [Hines et al 2014 ApJL 780 L32] Atthese projected distances average color slope was found to be ~6per 100 nm [Li et al 2013 ApJL 779 L3] When consideredsimultaneously these two features place significant constraint onthe physical and chemical properties of dust particles [Zubko et al2015 Planet Space Sci httpdxdoiorg101016jpss201508002]We model this response with agglomerated debris particles havinghighly irregular morphology and density of constituent materialbeing consistent with in situ studies of comets We considerparticles of 28 different refractive indices that correspond to in situstudies of comets and plausible assumptions on chemicalcomposition of cometary dust and ices What emerges from ouranalysis is that the ISON coma was chemically heterogeneous atthe epoch of observation The positive polarization at smallprojected distances suggests a high spatial concentration of highlyabsorbing materials such as amorphous carbon andor organicshighly irradiated with UV radiation At larger distances thenegative polarization P = ndash (16 plusmn 045) and color slope ~6 per100 nm appear consistent with organics slightly processed with UVradiation tholins Mg-Fe silicates and Mg-rich silicatescontaminated with ~10 (by volume) amorphous carbon Asignificant abundance of pure water-ice particles andor pure

Mg-rich silicates must be ruled out in this region These materialshave been found in situ in other comets and also detected withimaging polarimetry in the circumnucleus halo regions Analyses ofpolarimetric images suggest that Mg-rich silicates could originatefrom a refractory surface layer on the surface of cometary nuclei[Zubko et al 2012 AampA 544 L8] A depletion of such particles inComet ISON could imply an absence of such a layer on its nucleus

Author(s) Gorden Videen Evgenij Zubko Dean C Hines Yuriy Shkuratov Vadym Kaydash Karri Muinonen MatthewW Knight Michael L Sitko Carrey M Lisse Max Mutchler Diane H Wooden Jian-Yang Li Hiroshi KobayashiInstitution(s) 1 Johns Hopkins University APL 2 NagoyaUniversity 3 NASA Ames Research Center 4 Planetary ScienceInstitute 5 Space Science Institute 6 Space Telescope ScienceInstitute 7 University of Helsinki 8 VN Karazin KharkovNational University

41514 ndash Radio OH spectroscopic mapping survey of 26comets Trends in outflow velocity and collisionalquenchingBetween 2000-2015 we obtained 18cm OH spectra of 26 cometsusing the Arecibo Observatory 305m Gordon Telescope and theNational Radio Astronomy Observatory 100m R W Byrd GreenBank Telescope (GBT) Spectra of both long-period and periodiccomets were obtained at 1667 and 1665 MHz (18cm wavelength)with a beam resolution of 29 arcminutes at Arecibo and 74arcminutes at GBT Heliocentric distances for comets in the samplerange between 04 to 28 AU with gas production rates from01--30 x 10 mols A wide range of gas velocities are observedfrom 05 to nearly 2 kms with the highest variability in outflowvelocities for comets at heliocentric distances less than 1 AUMapping observations provide a direct constraint on the radiuswithin which there is collisional quenching an important factor inestimating total water production rates and a useful constraint oncoma density We find that collisional quenching variesconsiderably and generally exceeds what might be expectedtheoretically so it is best when observations make a directconstraint on this value We will present aggregate velocity gasproduction and quenching results from this comet survey derivedfrom a kinetic model utilizing Monte Carlo simulations

Author(s) Amy J Lovell Ellen S HowellInstitution(s) 1 Agnes Scott College 2 LPLU Arizona

41515 ndash High-resolution spectroscopy of the CN redsystem in comet C2013 R1 (Lovejoy) using WINEREDat Koyama Astronomical ObservatoryCN radical has the strong electronic transition moments in opticalwavelength region and CN has extensively observed in cometsEspecially the CN violet system (B Σ mdashX Σ ) has been observedby using high-resolution spectroscopic technique in order to inferthe isotopic ratios of carbon and nitrogen in comets via C N

C N and C N However the wavelength range for thissystem (~388 nm) is severely extinct if a comet is close to the Sun(we have to observe the comet at low elevations from theground-based observatories) On the other hand CN radical alsohas the strong electronic transition in near-infrared (~11 microns)the CN red system (A Π mdashX Σ ) Although there are few reportson the high-resolution spectra of this band in comets thiswavelength region is not severely affected by the telluric extinctionand considered as the new window for the observations of thecarbon and nitrogen isotopic ratios in cometsHigh resolution near-infrared spectra of comet C2013 R1(Lovejoy) using the WINERED (R~3x10 ) spectrometer mountedon the 13-m Araki telescope at Koyama Astronomical Observatorywere acquired on UT 2013 Nov 30 The heliocentric and geocentricdistances were 091 AU and 049 AU respectively We detectedstrong emission lines of the CN red system (00) at around 11microns The rotational line intensities of this band approximatelyfollow the Boltzmann distribution at ~300K for our observationsWe present the detailed analysis of the CN red system in cometC2013 R1 (Lovejoy) and discuss about the isotopic ratios in CN

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This research program is supported by the MEXT --- SupportedProgram for the Strategic Research Foundation at PrivateUniversities 2014 ndash 2018 and partially supported by JSPS15J10864

Author(s) Hideyo Kawakita Yoshiharu Shinnaka SoheiKondo Satoshi Hamano Hiroaki Sameshima KenshiNakanishi Takafumi Kawanishi Tetsuya Nakaoka ShogoOtsubo Masaomi Kinoshita Yuji Ikeda Ryo Yamamoto Natsuko Izumi Kei Fukue Chikako Yasui Hiroyuki Mito Yuki Sarugaku Noriyuki Matsunaga Naoto KobayashiInstitution(s) 1 Kyoto Sangyo University 2 LIH KoyamaAstronomical Observatory 3 National AstronomicalObservatory 4 University of Tokyo

41516 ndash Nitrogen Isotopic Ratios in Cometary NH Implication for N-fractionation in AmmoniaIsotopic ratios in cometary molecules are diagnostic for thephysico-chemical conditions where molecules formed and areprocessed from the interstellar medium to the solar nebulaUsually temperatures at the molecular formation control thefractionation of the heavier element in molecular species egD-fractionation in waterIn cometary volatiles the N N ratios in CN have been wellobserved (Manfroid et al 2009 AampA 503 613 and referencetherein) and is consistent with the ratio in HCN (a most probableparent of CN) measured in few comets (Bockeleacutee-Morvan et al2008 ApJ 679 L49) Those ratios are enriched compared to theproto-solar value by a factor of ~3 In contrast to those Nitrilesthere are only few reports on N N ratios in Ammonia (asAmine) (Rousselot et al 2014 ApJ 780 L17 Shinnaka et al 2014ApJ 782 L16) Ammonia (NH ) is usually the most abundant andHCN is the second most abundant N-bearing volatiles in cometaryice Especially recent observations of NH revealed the N Nratios in NH are comparable to those of CN However from theviewpoint of theoretical work the enrichment of N in cometaryNH cannot be reproduced by current chemical network modelsInformation about the diversity of the N N ratios in NH ofindividual comets is needed to understand the formationmechanismsenvironments of NH in the early solar systemTo clarify the diversity of the N N ratios in cometary NH wedetermine the N N ratios in NH for more than ten cometsindividually which include not only Oort cloud comets but alsoshort period comets by using the high-resolution optical spectra ofNH These spectra were obtained with both the UVES mountedon the VLT in Chile and the HDS on the Subaru Telescope inHawaiiThe derived N N ratios in NH for more than ten comets showhigh N-enrichment compared with the elemental abundances ofnitrogen in the Sun by about factor of ~3 and has no large diversitydepending on these dynamical properties We discuss about theorigin of the formation conditions of cometary NH and itsphysico-chemical evolution in the solar nebula based on our andother resultsThis work was supported by JSPS 15J10864 (Y Shinnaka)

Author(s) Yoshiharu Shinnaka Hideyo Kawakita Emmanueumll Jehin Alice Decock Damien Hutsemeacutekers JeanManfroid Akira AraiInstitution(s) 1 Koyama Astronomical Observatory of KyotoSangyo University 2 LESIA Observatoire de Paris 3 NationalAstronomical Observatory of Japan 4 Universiteacute de Liegravege

41517 ndash Spectroscopic studies of the molecularparentage of radical species in cometary comaeWe have observed several comets using an integral-field unitspectrograph (the George and Cynthia Mitchell Spectrograph) onthe 27m Harlan J Smith telescope at McDonald ObservatoryFull-coma spectroscopic images were obtained for various radicalspecies (C2 C3 CH CN NH2) By constructing azimuthal averageprofiles from the full-coma spectroscopic images we can test Hasermodel parameters with our observations The Haser model wasused to determine production rates and possible parent lifetimesthat would be consistent with the model By iterating through a

large range of possible parents lifetimes we can see what range ofvalues in which the Haser model is consistent with observationsAlso this type of analysis gives us perspective on how sensitive themodels fit quality is to changes in parent lifetimes Here wepresent the work completed to date and we compare our results toother comet taxonomic surveys

Author(s) Benjamin Lewis Donna Pierce Anita CochranInstitution(s) 1 Mississippi State University 2 UT-Austin

41518 ndash Gone in a Blaze of Glory the Demise of CometC2015 D1 (SOHO)We present studies of C2015 D1 (SOHO) the first sunskirtingcomet ever seen from ground stations over the past half centuryThe Solar and Heliospheric Observatory (SOHO) witnessed itspeculiar light curve with a huge dip followed by a flareup aroundperihelion the dip was likely caused by sublimation of olivinesdirectly evidenced by a coincident temporary disappearance of thetail The flareup likely reflects a disintegration event which wesuggest was triggered by intense thermal stress established withinthe nucleus interior Photometric data reveal an increasingly dustycoma indicative of volatile depletion A catastrophic mass loss rateof ~10 kg s around perihelion was seen Ground-basedXingming Observatory spotted the post-perihelion debris cloudOur morphological simulations of post-perihelion images findnewly released dust grains of size a gt~ 15 μm in radius however atemporal increase in a was also witnessed possibly due to swiftdispersions of smaller grains swept away by radiation forceswithout replenishment Together with the fading profile of the lightcurve a power law dust size distribution with index γ = 32 plusmn 01 isderived We detected no active remaining cometary nuclei over~01 km in radius in post-perihelion images acquired at LowellObservatory Applying radial non-gravitational parameter A =(1209 plusmn 0118) times 10 AU day from an isothermal water-icesublimation model to the SOHO astrometry significantly reducesresiduals and sinusoidal trends in the orbit determination Thenucleus mass ~10 --10 kg and the radius ~50--150 m (bulkdensity ρ = 04 g cm assumed) before the disintegration arededuced from the photometric data consistent results weredetermined from the non-gravitational effects

Author(s) Man-To Hui Quan-Zhi Ye Matthew ManningKnight Karl Battams David ClarkInstitution(s) 1 Department of Earth Planetary and SpaceSciences UCLA 2 Department of Physics and AstronomyUniversity of Western Ontario 3 Lowell Observatory 4 NavalResearch Laboratory

41519 ndash The Plasma Environment in Comets Over aWide Range of Heliocentric Distances Application toComent C2006 P1 (McNaught)On 2007 January 12 comet C2006 P1 (McNaught) passed itsperihelion at 017 AU Abundant remote observations offer plentyof information on the neutral composition and neutral velocitieswithin 1 million kilometers of the comet nucleus In early Februarythe Ulysses spacecraft made an in situ measurement of the ioncomposition plasma velocity and magnetic field when passingthrough the distant ion tail and the ambient solar wind Themeasurement by Ulysses was made when the comet was at around08 AU With the constraints provided by remote and in situobservations we simulated the plasma environment of CometC2006 P1 (McNaught) using a multi-species comet MHD modelover a wide range of heliocentric distances from 017 to 175 AUThe solar wind interaction of the comet at various locations ischaracterized and typical subsolar standoff distances of the bowshock and contact surface are presented and compared to analyticsolutions We find the variation in the bow shock standoffdistances at different heliocentric distances is smaller than thecontact surface In addition we modified the multi-species modelfor the case when the comet was at 07 AU and achievedcomparable water group ion abundances proton densities plasmavelocities and plasma temperatures to the UlyssesSWICS andSWOOPS observations We discuss the dominating chemicalreactions throughout the comet-solar wind interaction region and

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demonstrate the link between the ion composition near the cometand in the distant tail as measured by Ulysses The work at theUniversity of Michigan was supported by the NASA PlanetaryAtmospheres grant NNX14AG84G

Author(s) Yinsi Shou Michael Combi Yingdong Jia Tamas Gombosi Gabor Toth Martin RubinInstitution(s) 1 UCLA 2 University of Bern 3 University ofMichigan

41520 ndash Planets Perturbing Planetoids How Clear IsThe NeighborhoodIAU Resolution B5 adopted in Prague in 2006 states that acelestial body needs to have cleared the neighbourhood around itsorbit to qualify as a planet Pluto orbits within the Kuiper Belt soit does not meet this criterion but presumably the existence ofEarth-crossing asteroids does not disqualify the Earth fromplanetary status Stern and Levison (2002) Soter (2006) andMargot (2015) used equivalent criteria for planethood based on agravitational scattering parameter Λ which is proportional to thesquare of the planets mass and inversely proportional to its orbitalperiod This parameter assumes the small bodies to be clearedbegin with orbits like that of the planet In reality small bodies arefed in to the region of the planet at a more-or-less steady rate forinstance some main-belt asteroids become Near-Earth Asteroidswhile Kuiper Belt Objects can become Centaurs I will presentorbital integrations of small bodies from their source regions toquantify their steady-state populations at each planet in our SolarSystem and will compare the results with predictions from arefined version of the Λ parameterMargot J-L (2015) arXiv150706300Soter S (2006) Astron J 132 2513-2519Stern SA Levison HF (2002) in Highlights of Astronomy Vol12 pp 205-213

Author(s) Henry C (Luke) DonesInstitution(s) 1 Southwest Research Inst

41521 ndash Finding long-lost Comet LexellComet D1770 L1 (Lexell) made the closest observed pass by acomet to the Earth at approximately 0015 AU on 1 July 1770 Anaked-eye object observed by many astronomers of the time it wassubsequently lost the best contemporary estimates had it removedfrom its 1770 orbit by Jupiter in 1779 and sent to the outer SolarSystemNear-Earth asteroid 2010 JL33 has an orbit similar to that followedby Lexells comet during its observed apparition However thisNEAs nominal orbit which is well-known on the basis of adecade-long arc which includes radar observations does notapproach the Earth at the correct time to be Lexells comet That isunless modest non-gravitational forces are applied in which casethe famous near-miss can be reproducedModern measurements of 2010 JL33 together with those Lexellscomet made in the 18th century -which include motion exceeding40 degrees per day on the sky at closest approach- provideexquisite constraints on the dynamical processes at workcometary Yarkovsky or other I will discuss the implications of andthe conditions required for asteroid 2010 JL33 to be in factlong-lost comet Lexell

Author(s) Paul WiegertInstitution(s) 1 Univ of Western Ontario

41522 ndash A Continuing Analysis of Possible ActivityDrivers for the Enigmatic Comet 29PSchwassmann-Wachmann 1We present results from our continuing effort to understandactivity drivers in Comet 29PSchwassmann-Wachmann 1 (SW1)While being in a nearly circular orbit around 6 AU SW1 iscontinuously active and experiences frequent outbursts Ourgrouprsquos effort is focusing on finding constraints on physical anddynamical properties of SW1rsquos nucleus and their incorporation intoa thermophysical model [12] to explain this behavior Now we areanalyzing coma morphology of SW1 before during and after

outburst to place constraints on the spin-pole direction spinperiod and surface areas of activity (a spin period lower limit hasbeen measured) Also we are using the thermal model toinvestigate if the continuous activity comes from one or multipleprocesses such as the release of trapped supervolatiles during theamorphous to crystalline (A-C) water ice phase transition andorthe direct sublimation of pockets of supervolatile ices which maybe primordial or from the condensation of gases released duringthe A-C phase transition To explain the possibly quasi-periodic butfrequent outbursts we are looking into subsurface cavities whereinternal pressures can build reaching and exceeding surroundingmaterial strengths [34] andor thermal waves reaching a pocket ofsupervolatile ices causing a rapid increase in the sublimation rateFor all these phenomena the model is constrained by comparingthe output dust mass loss rate and its variability with what has beenobserved through optical imaging of the comet at various points inits orbit We will present preliminary thermal modeling of ahomogeneous progenitor nucleus that evolves into a body showinginternal material layering the generation of CO and CO2 icepockets and the production of outbursts thus bringing us closer toexplaining the behavior of this intriguing comet[1] Sarid G et al 2005 PASP 117 843 [2] Sarid G 2009 PhDThesis Tel Aviv Univ [3] Gronkowski P 2014 Astron NachrAN2 No 335 124-134 [4] Gronkowski P and Wesolowski M2015 MNRAS 451 3068-3077 We thank the NASA Outer PlanetsResearch Program (NNX12AK50G) and the Center for Lunar andAsteroid Surface Science (CLASS NNA14AB05A) for support ofthis work

Author(s) Charles Alfred Schambeau Yanga Fernandez Nalin Samarasinha Gal Sarid Beatrice Mueller Karen Meech Laura WoodneyInstitution(s) 1 California State University San Bernardino 2Florida Space Institute 3 Institute for Astronomy 4 PlanetaryScience Institute 5 University of Central Florida

41523 ndash Investigating the Spatial Structure of HCNEmission in Comet C2012 F6 (Lemmon)Comets are of particular interest in the field of Astrochemistry asthey can be used as a direct probe of formation chemistry of theSolar System Originating in the Oort Cloud reservoir these longperiod objects experience relatively limited solar influence Themajority of cometary material (water methane and ammonia ices)has remained in the same state as when it formed These ices areprecursors to more complex molecules which have been shown toform amino acids that are crucial for the development of life HCNor hydrogen cyanide is of particular interest because it can formthe nucleobase adenine (C H N ) The goals of this project are tomap the HCN distribution of Comet C2012 F6 (Lemmon) and toshow the simultaneous observation capabilities of the AtacamaLarge MillimeterSubmillimeter Array (ALMA) which allows theextraction of 7-m array 12-m array and single dish observationdata On UT 2013 May 11 Comet Lemmon was observed usingALMA The Cycle 1 configuration was used with the Band 6receivers with a 15 GHz range centered on the HCN transition at26586 GHz which gave a spectral resolution of 007 kms Weshow that Comet Lemmon has both a compact HCN region (foundwith the 12-m array) and also an extended component forming atail-like structure in the anti-motion direction (found with the 7-marray) We were also able to extract the autocorrelation data (singledish) and show that it is viable This project was supported andfunded by NRAO in conjunction with the National ScienceFoundation (NSF) with special thanks to the AstronomyDepartment at University of Virginia

Author(s) Shawn Booth Andrew Burkhardt JoannaCorby Niklaus Dollhopf Mark Rawlings Anthony RemijanInstitution(s) 1 National Radio Astronomy Observatory 2University of Virginia

41524 ndash New Analysis of the Deep Impact Comet9PTempel 1 Event Using High ResolutionSpectroscopy Evidence for High Velocity Long-LivedEmission from 630 nm [O( 1 D)] Emission

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Thorough analysis of narrow bandpass high spectral resolution (Rasymp100000) observations of [O 1 D] 630nm emission from comet9PTempel 1 taken over a ~1rsquo FOV both before and after the DeepImpact event provides evidence for a long-lived high velocityjet-like feature The observations were obtained with anall-reflective spatial heterodyne spectrometer (SHS) coupled to theMcMath-Pierce Main telescope Several spectra centered onTempel 1 were acquired during the period of 07042005-07062005 UT We report here on the presence and evolution of acometary emission feature that appears consistently andexclusively in the post-impact narrow-band spectra centered nearthe telluric [O 1 D] 630nm emission line This cometary emissionfeature shows substantial and distinct Doppler shifts overconsecutive post-impact observational nights and if the feature isthe anticipated [O 1 D] the corresponding line of sight velocitiesare -134 to -65 kms relative to the cometrsquos rest frame

Author(s) Jason B Corliss Walt M Harris Edwin JMierkiewicz Frederick L RoeslerInstitution(s) 1 Embry-Riddle Aeronautical University 2University of Arizona - LPL 3 University of Wisconsin-Madison

41525 ndash Detection of known meteoroid streams usingPan-STARRSMeteors are produced from meteoroids that are Near Earth Objects(NEOs) Created from the disruption of comets and asteroids theirstudy allows for the physical and chemical properties of parentbodies to be better constrained Because most meteoroids are toosmall to be directly observed in space ground-based cameranetworks (such as Weryk et al 2008) are often used to detectfireballs produced from centimetre sized objects and their massinflux can be extrapolated to larger sizesThe masssize distribution of meteoroid streams is an importanttopic relating directly to the impact hazard to the Earth (see Brownet al 2015) Unfortunately the largest meteoroids interact withthe Earthrsquos atmosphere so infrequently that their observation isvery biased and not predictable but due to their large size theymay be visible in space Barabanov and Smirnov (2005) presenteddetections of large possibly cometary meteoroids over 5 m indiameter but their results could not be confirmed by Beech et al(2004) More recently Micheli and Tholen (2015) looked forobjects in the meteoroid streams of several major showers butfound no stream objectsThe Pan-STARRS1 (PS1) telescope operated by the University ofHawai`i has a large seven square degree field-of-view which canreliably detect new NEOs However not every NEO candidate isfollowed up and linked into a well established orbit possibly due tothe fact that the smallest bodies will not be visible at the sensitivitylimit of PS1 for very long or that their predicted orbit is uncertainso follow up telescopes look in the wrong location In this work wepresent our results to date about searching for potential meteoroidstreams (with an emphasis on cometary streams) with the PS1telescope using its multi-year database of unlinked NEOdetections For recent observations where possible we haveobserved the true non-geocentric radiants directly during peakshower activity The detection of known meteoroid streams willallow for additional follow up studies with other telescopes

Author(s) Robert J Weryk Richard J WainscoatInstitution(s) 1 Univ of Hawaii

416 ndash Characterization of Extrasolar Planets41601 ndash The effects of H -He pressure broadeningparameters on the retrieval of brown dwarfatmospheresBrown dwarf atmospheres are compositionally very similar to thegas giant planets made up of approximately 85 H and 15 Heas well as other trace gases such as CH and H O depending onthe spectral type We have investigated the effects of using pressurebroadening parameters related to H -He broadening andcompared them to using air-broadening parameters for each of themajor trace gases involved in brown dwarf atmospheres We have

identified from limited data sets that H -He broadening relative toair broadening can act to increase or decrease the Lorentzianbroadening experienced by a given transition This change inLorentzian broadening is dependent on the gas considered and thetransitions associated quantum numbers (such as rotational andvibrational quantum numbers) By altering the transitionrsquoslineshape we also alter its opacity Some gases are affectedsignificantly at all pressure levels (NH CO CH ) some at deep(~1bar) pressure levels (CO H O) and others not at all (TiO VO)We conclude however that these limited data sets do not providethe complex and comprehensive dependence of pressurebroadening on the relevant quantum numbers that is available toair broadening and we cannot say for certain how much this limitsour results until more data is available Our conclusionsdemonstrate the need for further study of H and He broadeningparameters for the relevant gases from both experimental andcomputational means We present preliminary results of theknock-on effects that these broadening parameters have for theretrieval of atmospheric composition and thermal structure

Author(s) Ryan Garland Patrick G J Irwin SuzanneAigrain Joanna K BarstowInstitution(s) 1 University of Oxford

41602 ndash Spitzer Secondary Eclipse Observations ofHot-Jupiters WASP-26b and CoRoT-1bWASP-26b is a hot-Jupiter planet that orbits an early G star every27566 days at a distance of 003985 AU Using the Spitzer SpaceTelescope in 2010 as a part of the Spitzer Exoplanet Target ofOpportunity program (program 60003) we observed two secondaryeclipses of the planet one in the 36 μm channel on 7 Septemberand one in the 45 μm channel on 3 August We also reanalizearchival Spitzer data of CoRoT-1b which is another hot Jupiterorbiting a G star every 15089686 days at a distance of 00254 AUin the 36 and 45 μm channels The eclipse depths for WASP-26bare 000117 plusmn 000012 and 0001507 plusmn 000016 for the 36 and 45μm channels respectively The eclipse depths for CoRoT-1b are00047 plusmn 00003 and 00046 plusmn 00004 respecitvely We also refinetheir orbits using our own secondary eclipse measurements incombination with external radial-velocity and transit observationsfrom both professional and amateur observers Using our BayesianAtmostpheric Radiative Transfer code we characterize theatmospheres of these planets Spitzer is operated by the JetPropulsion Laboratory California Institute of Technology under acontract with NASA This work was supported by NASA PlanetaryAtmospheres grant NNX12AI69G and NASA Astrophysics DataAnalysis Program grant NNX13AF38G Blecic holds a NASA Earthand Space Science Fellowship

Author(s) Emerson DeLarme Joseph Harrington PatricioCubillos Jasmina Blecic Andrew SD Foster Justin Garland AJFoster Andrew Collier CameronInstitution(s) 1 University of Central Florida 2 University ofSt Andrews

41604 ndash Observation and Analysis of SecondaryEclipses of WASP-32bWe report two Spitzer secondary eclipses of the exoplanetWASP-32b Discovered in 2010 by Maxted et al this hot-Jupiterplanet has a mass of 36 plusmn 007 M a radius of 118 plusmn 007 R anequilibrium temperature of 1560 plusmn 50 K and an orbital period of271865 plusmn 000008 days around a G-type star We observed twosecondary eclipses in the 36 microm and 45 microm channels using theSpitzer Space Telescope in 2010 as a part of the Spitzer ExoplanetTarget of Opportunity program (program 60003) We presenteclipse depth estimates of 00013 plusmn 000023 in the 45 microm bandand inconclusive results in the 36 microm band We also report aninfrared brightness temperature of 1538 plusmn 110 in the 45 micromchannel and refinements of orbital parameters for WASP-32b fromour eclipse measurement as well as amatuer and professional datathat closely match previous results Spitzer is operated by the JetPropulsion Laboratory California Institute of Technology under acontract with NASA This work was supported by NASA PlanetaryAtmospheres grant NNX12AI69G and NASA Astrophysics Data

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Analysis Program grant NNX13AF38G JB holds a NASA Earth andSpace Science Fellowship

Author(s) Justin Garland Joseph Harrington Patricio ECubillos Jasmina Blecic Andrew S Foster Oliver Bowman Pierre F L MaxtedInstitution(s) 1 University of Central Florida 2 University ofKeele

41605 ndash Secondary eclipse observations and theatmosphere of exoplanet WASP-34bWASP-34b is a short-period exoplanet with a mass of 059 plusmn 001Jupiter masses orbiting a G5 star with a period of 43177 days andan eccentricity of 0038 plusmn 0012 (Smalley 2010) We observedWASP-34b using the 36 and 45 μm channels of the Infrared ArrayCamera aboard the Spitzer Space Telescope in 2010 (Program60003) We applied our Photometry for Orbits Eclipses andTransits (POET) code to present eclipse-depth measurementsestimates of infrared brightness temperatures and a refined orbitWith our Bayesian Atmospheric Radiative Transfer (BART) codewe characterized the atmospheres temperature and pressureprofile and molecular abundances Spitzer is operated by the JetPropulsion Laboratory California Institute of Technology under acontract with NASA This work was supported by NASA PlanetaryAtmospheres grant NNX12AI69G and NASA Astrophysics DataAnalysis Program grant NNX13AF38G J Blecic holds a NASAEarth and Space Science Fellowship

Author(s) Ryan C Challener Joseph Harrington PatricioCubillos Justin Garland Andrew S D Foster Jasmina Blecic AJ Foster Barry SmalleyInstitution(s) 1 Keele University 2 University of CentralFlorida

41606 ndash Atmospheric Orbital and Eclipse DepthAnalysis of the Hot Jupiter HAT-P-30-WASP-51bHAT-P-30-WASP-51b is a hot-Jupiter planet that orbits an F starevery 28106 days at a distance of 00419 AU Using the SpitzerSpace Telescope in 2012 (Spitzer Program Number 70084) weobserved two secondary eclipses of the planet one in the 36 μmchannel on 3 January and one in the 45 μm channel on 17January We present eclipse-depth measurements of 000163 plusmn00001 and 000146 plusmn 000013 and we esitmate the infraredbrightness temperatures to be 1900 plusmn 50 and 1600 plusmn 60 for thesetwo channels respectively from an analysis using our Photometryfor Orbits Eclipses and Transits (POET) pipeline We also refineits orbit using our own secondary-eclipse measurements incombination with radial-velocity and transit observations fromboth professional and amateur observers The most notable resultfrom this orbital analysis is a detection of eccentricity in theplanets orbit Using only the phase of our secondary eclipses wecan constrain ecosw to a minimum of 00084 plusmn 00004 a 20 sigmadetection of one component of the orbits eccentricity that isindependent of the effects that stellar tides have on radial velocitydata We then characterize its atmospheres temperature- pressureprofile and molecular abundances using our Bayesian AtmosphericRadiative Transfer code (BART) Spitzer is operated by the JetPropulsion Laboratory California Institute of Technology under acontract with NASA This work was supported by NASA PlanetaryAtmospheres grant NNX12AI69G and NASA Astrophysics DataAnalysis Program grant NNX13AF38G J Blecic holds a NASAEarth and Space Science Fellowship

Author(s) Andrew S Foster Joseph Harrington PatricioCubillos Jasmina Blecic A J Foster Ryan Challener JustinGarlandInstitution(s) 1 University of Central Florida

41607 ndash Chemical uncertainties in modeling hotJupiters atmospheresMost predictions and interpretations of observations in beyond ourSolar System have occurred through the use of 1D photo-thermo-chemical models Their predicted atmospheric compositions arehighly dependent on model parameters Chemical reactions are

based on empirical parameters that must be known attemperatures ranging from 100 K to above 2500 K and at pressuresfrom millibars to hundreds of bars Obtained from experimentscalculations and educated-guessed estimations these parametersare always evaluated with substantial uncertainties Howeveralthough of practical use few models of exoplanetary atmosphereshave considered these underlying chemical uncertainties and theirconsequences Recent progress has been made recently that allowus to (1) evaluate the accuracy and precision of 1D models ofplanetary atmospheres with quantifiable uncertainties on theirpredictions for the atmospheric composition and associatedspectral features (2) identify the lsquokey parametersrsquo that contributethe most to the models predictivity and should therefore requirefurther experimental or theoretical analysis (3) reduce andoptimize complex chemical networks for their inclusion inmultidimensional atmospheric modelsFirst a global sampling approach based on low discrepancysequences has been applied in order to propose error bars onsimulations of the atmospheres HD 209458b and HD 189733busing a detailed kinetic model derived from applied combustionmodels that was methodically validated over a range oftemperatures and pressures typical for these hot Jupiters Atwo-parameters temperature-dependent uncertainty factor hasbeen assigned to each considered rate constant Second a globalsensitivity approach based on high dimensional modelrepresentations (HDMR) has been applied in order to identifythose reactions which make the largest contributions to the overalluncertainty of the simulated results The HDMR analysis has beenrestricted to the most important reactions based on a non-linearscreening method using Spearman Rank Correlation Coefficientsat different level of the modeled atmospheres The individualcontributions of some key reactions as highlighted by this analysiswill be discussed

Author(s) Eric Hebrard Shawn Domagal-GoldmanInstitution(s) 1 NASA Goddard Space Flight Center

41608 ndash On the parameterization of 1D verticalmixing in planetary atmospheres insights from 2Dand 3D simulationsMost of the current atmospheric chemistry models for planets (egKrasnopolsky amp Parshev 1981 Yung amp Demore 1982 Yung Allenamp Pinto 1984 Lavvas et al 2008 Zhang et al 2012) and exoplanets(eg Line Liang amp Yung 2010 Moses et al 2011 Hu amp Seager2014) adopt a one-dimensional (1D) chemical-diffusion approachin the vertical coordinate Although only a crude approximationthese 1D models have succeeded in explaining the global-averagedvertical profiles of many chemical species in observations One ofthe important assumptions of these models is that all chemicalspecies are transported via the same eddy diffusion profile--that isthe assumption is made that the eddy diffusivity is a fundamentalproperty of the dynamics alone and does not depend on thechemistry Here we show that as also noticed in the Earthcommunity (eg Holton 1986) this ldquohomogenous eddy diffusionrdquoassumption generally breaks down We first show analytically whythe 1D eddy diffusivity must generally depend both on thehorizontal eddy mixing and the chemical lifetime of the speciesThis implies that the long-lived species and short-lived chemicalspecies will generally exhibit different eddy diffusion profiles evenin a given atmosphere with identical dynamics Next we presenttracer-transport simulations in a 2D chemical-diffusion-advectionmodel (Shia et al 1989 Zhang Shia amp Yung 2013) and a 3Dgeneral circulation model (MITgcm eg Liu amp Showman 2013)for both rapid-rotating planets and tidally-locked exoplanets tofurther explore the effect of chemical timescales on the eddydiffusivity From the 2D and 3D simulation outputs we deriveeffective 1D eddy diffusivity profiles for chemical tracers exhibitinga range of chemical timescales We show that the derived eddydiffusivity can depend strongly on the horizontal eddy mixing andchemistry although the dependences are more complex than theanalytic model predicts Overall these results suggest that cautionis warranted when using 1D models with multiple species mixed bya single eddy diffusivity profile Possible consequences will bediscussed

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Author(s) Xi Zhang Adam P ShowmanInstitution(s) 1 University of Arizona 2 University ofCalifornia Santa Cruz

41609 ndash Atmospheres of partially differentiatedsuper-Earth exoplanetsTerrestrial exoplanets have been discovered in a range of sizesdensities and orbital locations that defy our expectations basedupon the Solar System Planets discovered to date with radii lessthan ~15-16 Earth radii all seem to fall on an iso-density curvewith the Earth [1] However mass and radius determinationswhich depend on the known properties of the host star are notaccurate enough to distinguish between a fully differentiatedthree-layer planet (core mantle oceanatmosphere) and anincompletely differentiated planet [2] Full differentiation of aplanet will depend upon the conditions at the time of accretionincluding the abundance of short-lived radioisotopes which willvary from system to system as well as the number of giant impactsthe planet experiences Furthermore separation of metal andsilicates at the much larger pressures found inside super-Earthswill depend on how the chemistry of these materials change at highpressures There are therefore hints emerging that not all super-Earths will be fully differentiated Incomplete differentiation willresult in a more reduced mantle oxidation state and may haveimplications for the composition of an outgassed atmosphere Herewe will present the first results from a chemical equilibrium modelof the composition of such an outgassed atmosphere and discussthe possibility of distinguishing between fully and incompletelydifferentiated planets through atmospheric observations[1] Rogers L 2015 ApJ 801 41 [2] Zeng L amp Sasselov D 2013PASP 125 227

Author(s) Laura Schaefer Dimitar SasselovInstitution(s) 1 Harvard University

41610 ndash A Novel Approach to Atmospheric Retrievalfor Small ExoplanetsRetrieval of environmental parameters from the spectra ofsub-Neptune and terrestrial extrasolar planets is extremelychallenging due to the observational difficulty the inherentcomplexity of planetary processes and the likely diversity ofenvironments for these small objects The best retrieval techniqueswill use observations of the star-planet system along withknowledge of planetary processes gleaned from objects in the SolarSystem to constrain retrieved environmental parametersWe present ongoing work of the Virtual Planetary Laboratory(VPL) to develop a versatile terrestrial atmosphere retrieval suitecapable of capturing a wide range of terrestrial planet processeswhile employing robust statistics Our novel approach is to producefits to observed spectra that discriminate between degeneratesolutions by considering limitations on planetary environmentsderived from known physics and chemistry The forward modelleverages the SMART 1-D line-by-line fully multiple-scattering andwidely validated radiative transfer model (Meadows amp Crisp 1996)as the primary workhorse for computing transit transmissionthermal emission and reflectance spectroscopy Following theapproach of the CHIMERA code (Line et al 2013 2014) we employa variety of inverse models for the problem of parameterestimation Here we present preliminary results using optimalestimation for terrestrial and sub-Neptune planets The model isbeing validated against synthetic Solar System and existingexoplanet observationsThis model will be used to explore the capabilities of key telescopearchitectures to understand information loss when planets areviewed as a point source and to provide a data analysis frameworkfor future sub-Neptune super-Earth and Earth analog exoplanetobservations

Author(s) Jacob Lustig-Yaeger Victoria Meadows MichaelLine David CrispInstitution(s) 1 Jet Propulsion Laboratory California Instituteof Technology 2 University of California Santa Cruz 3University of Washington

41611 ndash A study of temporal variability of clouds inexo-atmospheres using Earth observations as a proxyClouds are strongly linked to the dynamics of the atmosphere andhave been observed to vary over multiple spatial scales andtimescales on Earth and the planets hourly diurnal seasonalinterannual and decadal The study of such variations inexoplanetary atmospheres could only be made through lightlyconstrained general circulation models (GCMs) In most cases theexoplanet itself is unresolved from its star and individual cloudpatches and their variations cannot be observed Howevertemporal and spatial variation of cloud fields can have significantimplications for the interpreting the observed phase-curve of thelights from the star-exoplanet system yet it remains almost whollyunconstrained To address this issue we model Earth as anexoplanet to understand changes in observables due to temporaland spatial variations of clouds by leveraging the rich datasetsavailable for Earth In particular the International Satellite CloudClimatology Project (ISCCP) has compiled cloud observations onEarth in the past three decades producing a high-resolutiondataset We perform radiative transfer calculations using cloudprofiles sampled from this dataset to produce disc integratedbrightness and polarization phase curves which map seasonal andinterannual cloud variations This exercise gives us the first(pseudo)-observation based constraints for temporal variability ofclouds in exo-atmospheres

Author(s) Pushkar Kopparla Albert Zhai Alice Zhai HuiSu Jonathan H Jiang Yuk Ling YungInstitution(s) 1 California Institute of Technology 2 JetPropulsion Laboratory

41612 ndash Atmospheric Ozone Formation andObservation Effects on Waterless Rocky Exoplanetsaround M DwarfsIt is recently proposed that up to two thousand bars of Oatmospheres could buildup on rocky planets near M dwarfs as theresult of stellar luminosity evolution and runaway water loss(Luger and Barnes 2015) Here we use a one-dimensionalphotochemical model to study ozone distributions in thesehypothetical O -rich atmospheres Our study showed that ozonelayers in denser O atmospheres locate at higher altitudes than thatin the Earthrsquos atmospheres A higher ozone layer should generatestronger O absorption feature potentially different from that ofour Earth We also present the enhancement of transmissionspectral features which could be useful to identify such denseO -rich atmospheres by future exoplanet characterization missionsand facilities such as JWST

Author(s) Chuhong Mai Feng TianInstitution(s) 1 Center for Earth System Sciences TsinghuaUniversity 2 School of Earth and Space Exploration ArizonaState University

41613 ndash HSTWFC3 Updates Impacting ExoplanetObserversWe provide a summary of new Wide Field Camera 3 (WFC3)capabilities and updates to the Hubble Space Telescope (HST)proposal process of interest to exoplanet observers In particularwe discuss recent studies on high precision photometry with spatialscanning that show up to 01 photometric repeatability for theUVIS channel and 05 for the IR channel We describe a new IRsample sequence spars5 which may open up more orient rangesand scheduling opportunities for exoplanet targets Finally wepresent a new mid-cycle proposal scheme for HST that will allowobservers to apply for up to 5 orbits outside the standard annualcall for proposals this will be especially advantageous for observersof recently discovered exoplanets

Author(s) Catherine Gosmeyer Peter R McCullough Sylvia Baggett Elena SabbiInstitution(s) 1 Space Telescope Science Institute

41614 ndash Forward Models of Exoplanets forAtmosphere Retrievals with JWST

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We present models of extrasolar planets focusing on super-Earthsand mini-Neptunes and incorporating self-consistent treatment ofinternal structures radiative cooling and XUV-driven mass lossover time and atmosphere models with 1-D radiative transfer and arange of compositions and cloud structures These models aredesigned for performing retrievals of atmosphere parameters withdata from the upcoming JWST mission

Author(s) Alex Howe Adam BurrowsInstitution(s) 1 Princeton University

41615 ndash 3D modeling of clouds in GJ1214bsatmosphereGJ1214b is a warm mini-Neptunewaterworld and one of the fewlow-mass exoplanets whose atmosphere is characterizable bycurrent telescopes Recent observations indicated a flat transitspectrum in near-infrared which has been interpreted as thepresence of high and thick condensate clouds of KCl or ZnS orphotochemical hazes However the formation of such highcloudshazes would require a strong vertical mixing linked to theatmospheric circulation In order to understand the transportdistribution and observational implications of such cloudshazewe studied the atmospheric circulation and cloud formation onGJ1214b for H-dominated and water-dominated atmospheresusing the Generic LMDZ GCMFirstly we analyzed cloud-free atmospheres We showed that thezonal mean meridional circulation corresponds to an anti-Hadleycirculation in most of the atmosphere with upwelling at midlatitudeand downwelling at the equator This circulation should stronglyimpact cloud formation and distribution leading to a minimum ofcloud at the equator We also derived 1D equivalent eddy diffusioncoefficients The corresponding values should favor an efficientformation of photochemical haze in the upper atmosphere ofGJ1214bSecondly we simulated cloudy atmospheres including latent heatrelease and radiative effects for KCl and ZnS clouds We analyzedtheir impacts on the thermal structure In particular we fund thatZnS clouds may lead to the formation of a stratospheric thermalinversion We showed that flat transit spectra consistent with HSTobservations are possible for cloud particle radii around 05microns Using the outputs of our GCM we also generatedemission and reflection spectra and phases curvesFinally our results suggest that primary and secondary eclipsesand phase curves observed by JWST should provide strongconstraints on the nature of GJ1214bs atmosphere and clouds

Author(s) Benjamin Charnay Victoria Meadows Jeacutereacutemyleconte Amit Misra Giada ArneyInstitution(s) 1 LMD 2 University of Washington

41616 ndash Polarisation of Planets and ExoplanetsWe present observations of the linear polarisation of several hotJupiter systems with our new high-precision polarimeter HIPPI(HIgh Precision Polarimetric Instrument) By looking at thecombined light of the star and planet we aim to detect the polarisedlight reflected from the planets atmosphere This can provideinformation on the presence of and nature of clouds in theatmosphere and constrain the geometric albedo of the planet Themethod is applicable to both transitting and non-transittingplanets and can also be used to determine the inclination of thesystem and thus the true mass for radial velocity detected planetsTo predict and interpret the polarisation from such observationswe have also developed an advanced polarimetric modellingcapability by incoroporating full polarised radiative transfer intoour atmospheric modelling code VSTAR This is done using theVLIDORT vector radiative transfer solver (Spurr 2006) Theresulting code allows us to predict disc-resolved phase-resolvedand spectrally-resolved intensity and linear polarisation for anyplanet exoplanet brown dwarf or cool star atmosphere that can bemodelled with VSTAR We have tested the code by reproducingbenchmark calculations in polarised radiative transfer and by SolarSystem test cases including reproducing the classic Hansen andHovenier (1974) calculation of the polarisation phase curves ofVenus

Hansen JE amp Hovenier JW 1974 J Atmos Sci 31 1137Spurr R 2006 JQSRT 102 316

Author(s) Jeremy Bailey Lucyna Kedziora-Chudczer Kimberly Bott Daniel V CottonInstitution(s) 1 University of New South Wales

41617 ndash Constraining the Structure of Hot JupiterAtmospheres Using a Hybrid Version of the NEMESISRetrieval AlgorithmUnderstanding the formation environments and evolutionscenarios of planets in nearby planetary systems requires robustmeasures for constraining their atmospheric physical propertiesHere we have utilized a combination of two different parameterretrieval approaches Optimal Estimation and Markov Chain MonteCarlo as part of the well-validated NEMESIS atmospheric retrievalcode to infer a range of temperature profiles and molecularabundances of H O CO CH and CO from available daysidethermal emission observations of several hot-Jupiter candidatesIn order to keep the number of parameters low and henceforthretrieve more plausible profile shapes we have used a parametrizedform of the temperature profile based upon an analytic radiativeequilibrium derivation in Guillot et al 2010 (Line et al 20122014) We show retrieval results on published spectroscopic andphotometric data from both the Hubble Space Telescope andSpitzer missions and compare them with simulations from theupcoming JWST mission In addition since NEMESIS utilizescorrelated distribution of absorption coefficients (k-distribution)amongst atmospheric layers to compute these models updates tospectroscopic databases can impact retrievals quite significantly forsuch high-temperature atmospheres As high-temperature linedatabases are continually being improved we also compareretrievals between old and newer databases

Author(s) Mahmuda A Badhan Avi M Mandell BrigetteHesman Conor Nixon Drake Deming Patrick Irwin JoannaBarstow Ryan GarlandInstitution(s) 1 NASA Goddard Space Flight Center 2University of Maryland 3 University of Oxford

41618 ndash Photochemical hazes in planetaryatmospheres solar system bodies and beyondRecent transit observations of exoplanets have demonstrated thepossibility of a wide prevalence of hazecloud layers at highaltitudes Hydrocarbon photochemical haze could be the candidatefor such haze particles on warm sub-Neptunes but the lack ofevidence for methane poses a puzzle for such hydrocarbonphotochemical haze The CH CO ratios in planetary atmospheresvary substantially from their temperature and dynamics Anunderstanding of haze formation rates and plausible opticalproperties in a wide diversity of planetary atmospheres is requiredto interpret the current and future observations

Here we focus on how atmospheric compositions specificallyCH CO ratios affect the haze production rates and their opticalproperties We have conducted a series of cold plasma experimentsto constrain the haze mass production rates from gas mixtures ofvarious CH CO ratios diluted either in H or N atmosphere Themass production rates in the N -CH -CO system are much greaterthan those in the H -CH -CO system They are rather insensitiveto the CH CO ratios larger than at 03 Significant formation ofsolid material is observed both in H -CO and N -CO systemswithout CH4 in the initial gas mixtures The complex refractiveindices were derived for haze samples from N -CH H -CH andH -CO gas mixtures These are the model atmospheres for TitanSaturn and exoplanets respectively The imaginary part of thecomplex refractive indices in the UV-Vis region are distinct amongthese samples which can be utilized for modeling these planetaryatmospheres

Author(s) Hiroshi Imanaka Dale P Cruikshank Christopher P McKayInstitution(s) 1 NASA Ames Research Center 2 SETI Institute

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41619 ndash The HSTSTIS BAR5 Occulter High Contrastin Space at Visible WavelengthsThe Hubble Space Telescope currently has only one operationalhigh contrast imaging coronagraphic mode the 50CORON imagingmode of the Space Telescope Imaging Spectrograph (STIS)50CORON includes two intersecting wedges and two bar occultingmasks in an image plane ahead of the detector that block light frombright stars to reveal the faint emission from circumstellar disks orfaint companions Recently the smallest supported inner workingangle for these occulters was 03 We present in this poster thecommissioning of new occulting locations on the detector thatallow for inner working angles as close as 015 at the new BAR5position We show preliminary results for BAR5 using two nearbydebris disks AU Mic and Beta Pictoris and provide interested userswith a prescription for how to design their own high contrastimaging observations

Author(s) John H Debes Andras Gaspar GlennSchneider Charles ProffittInstitution(s) 1 STScI 2 The University of Arizona

41620 ndash ARIEL Atmospheric Remote-SensingInfrared Exoplanet Large-surveyMore than 1000 extrasolar systems have been discovered hostingnearly 2000 exoplanets Ongoing and planned ESA and NASAmissions from space such as GAIA Cheops PLATO K2 and TESSwill increase the number of known systems to tens of thousandsOf all these exoplanets we know very little ie their orbital dataand for some of these their physical parameters such as their sizeand mass In the past decade pioneering results have beenobtained using transit spectroscopy with Hubble Spitzer andground-based facilities enabling the detection of a few of the mostabundant ionic atomic and molecular species and to constrain theplanetrsquos thermal structure Future general purpose facilities withlarge collecting areas will allow the acquisition of better exoplanetspectra compared to the currently available especially from faintertargets A few tens of planets will be observed with JWST andE-ELT in great detailA breakthrough in our understanding of planet formation andevolution mechanisms will only happen through the observation ofthe planetary bulk and atmospheric composition of a statisticallylarge sample of planets This requires conducting spectroscopicobservations covering simultaneously a broad spectral region fromthe visible to the mid-IR It also requires a dedicated space missionwith the necessary photometric stability to perform thesechallenging measurements and sufficient agility to observemultiple times ~500 exoplanets over mission life-timeThe ESA-M4 mission candidate ARIEL is designed to accomplishthis goal and will provide a complete statistically significant sampleof gas-giants Neptunes and super-Earths with temperatures hotterthan 600K as these types of planets will allow direct observation oftheir bulk properties enabling us to constrain models of planetformation and evolutionThe ARIEL consortium currently includes academic institutes andindustry from eleven countries in Europe the consortium is openand invites new contributions and collaborations

Author(s) Giovanna TinettiInstitution(s) 1 University College London

417 ndash Discoveries and Dynamics ofExtrasolar Planets41701 ndash The NASA Exoplanet ArchiveThe NASA Exoplanet Archive is an online astronomical exoplanetand stellar catalog and data service that collates and cross-correlates astronomical data on exoplanets and their host stars andprovides tools to work with these data The Exoplanet Archive isdedicated to collecting and serving important public data setsinvolved in the search for and characterization of extrasolar planetsand their host stars The data include stellar parameters exoplanet

parameters and discoverycharacterization data from theastronomical literature The Archive also hosts mission and surveydata including Kepler pipeline data such as candidate lists and datavalidation products and ground-based surveys from SuperWASPand KELT Tools provided for users to work with these data includea transit ephemeris predictor light curve viewing utilities and aperiodogram service

Author(s) Rachel L AkesonInstitution(s) 1 NASA Exoplanet Science Institute Caltech

41702 ndash PICK2 Planets in Clusters with K2Open clusters are remarkable laboratories for a wide variety ofastrophysical investigations They comprise the mosthomogeneous samples of stars that we can ever hope to find Theyare stars that share the same age initial chemical compositiondistance and dynamical environment The fundamental propertythat distinguishes one star from another in a cluster is simply thestellar mass This gives us the very rare opportunity to conduct wellcontrolled astrophysical studies of stars and as a result there is avast astronomical literature focused on understanding andcharacterizing the members of stellar clustersWe are searching for transiting planets in five open clusters in theNASA K2 mission Fields 4 5 and 7 These clusters range in agefrom 125My (Pleiades) through the 625My ages of the Hyades andPraesepe up to the much older Ruprecht 147 (25 Gyr) and M67(3-5 Gyr) clusters Examination of the distribution of planetaryorbital parameters as well as the planetary multiplicity radius andmass distributions as a function of stellar age (and in comparisonwith field stars from both K2 and Kepler) will provide a powerfultest of theories of planetary system formation and dynamicalevolution The radii of hot Jupiters and Saturns as a function ofcluster age will provide a sensitive test of theories to explain thepopulation of inflated hot JupitersOur team will process the K2 pixel files into light curves for eachtarget star and will then search these light curves for possibleplanet transit events We will apply standard vetting procedures toremove likely false-positives and we will then model the transitprofiles We will then conduct an extensive set of ground-basedfollow-up observations using a wide range of observationalfacilities at our disposal These will include imaging highresolution visible and near-IR spectroscopy precise radial velocitymeasurement and ground-based observations of further transitsas appropriate

Author(s) William D Cochran Michael Endl Marshall CJohnson Byeong-Cheol Lee Chan Park Inwoo Han HeikeRauer Juan Cabrera Szilard Csizmadia Martin Paetzold David Yong Martin Asplund Artie P HatzesInstitution(s) 1 Aust Nat Univ 2 DLR 3 KASI 4 TLSTautenburg 5 Univ Koumlln 6 Univ of Texas Austin

41703 ndash An Exo-Venus Around a Cool Nearby StarWe present the discovery and planetary confirmation of KOI-3138a likely Earth-sized (108 Earth radii ) planet in a 9-day orbitaround a nearby M Dwarf star A planet transit was detected aroundKOI-3138 with the Kepler spacecraft and confirmed via falsepositive analysis using data from the UK Infrared telescope DigitalSky Survey and DSSI Speckle imaging The planetrsquos short orbitalperiod places it close to its host star making it an interesting Venusanalog around a cool starIt remains possible although unlikely that KOI-313801 insteadorbits a bound undetected binary companion to KOI-3138 Underthese conditions the planet becomes a mini-Neptune-sized planetorbiting a brown dwarf with a mass of ~005 solar mass Follow-upradial velocity measurements on the host star are required in orderto accurately assess the likelihood of this possibility Specificallydetection of a significant radial velocity ( ~725 ms) uponobservation of KOI-3138 will indicate the presence of a boundcompanion that was not detected by our false positive analysisprocedures Such a companion if detected cannot be ruled out asthe host star around which KOI-313801 orbitsKOI-313801 is too small to induce a detectable ldquowobble in its host

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star We therefore make no conclusions about mass orcomposition However there is reasonable incentive to determinethese properties in the hopes of understanding the nature ofhabitable zones around M-type stars Kepler-186f a previouslydiscovered Earth-like exoplanet is similar in size to KOI-313801and orbits the outer reaches of its starrsquos conservative habitablezone KOI-313801 also Earth-sized orbits a similar star butresides much closer in The two planets together span the range ofdistances within the habitable zones of M Dwarfs Determining thecomposition and atmosphere of KOI-313801 is therefore useful inunderstanding the nature of habitable zone boundaries of such startypes This task may in fact be possible with the James Webb SpaceTelescope (JWST) which will characterize atmosphericcompositions of nearby Earth-sized planets like KOI-313801 andthereby provide insight into the habitability of both known andto-be-discovered exoplanets

Author(s) Isabel Angelo Jason F Rowe Steve B HowellInstitution(s) 1 NASA Ames Research Center 2 UC Berkeley

41704 ndash Connections among spacing compositionand flatness in super-Earth systemsThe collection of thousands of super-Earths discovered by theKepler Mission contains a wealth of information about the processof planet formation Their spacing distribution is an archaeologicalartifact of the final stages of planet formation when planets growfrom embryos to super-Earths We explore how the interplaybetween stirring and mergers establishes the spacing distributionand links it to the composition and flatness of planets in thesystem with the latter influenced by damping by residual gas Weshow how these links manifest in Kepler observables such asperiod ratio number of transiting planets and transit durationratios Our study theoretically motivates connections betweenarchitectures and compositions that reflect conditions during theend stages of planet formation and are not merely the result ofselection effects

Author(s) Rebekah Ilene Dawson Eve J Lee EugeneChiangInstitution(s) 1 University of California Berkeley

41705 ndash Spin-Orbit Misalignment of Two-Planet-System KOI-89 via Gravity DarkeningWe investigate the causes of spin-orbit misalignment in exoplanetsystems via two-planet-system KOI-89 This system is of particularinterest because it can experimentally constrain the numerousoutstanding hypotheses that have been proposed to generatemisalignments We constrain both the spin-orbit angles and therelative alignment between the planes of the two orbits usinggravity darkening By fitting KOI-89s 17 long cadence quarters ofKepler photometry we show that the 85-day-orbit and208-day-orbit planets are misaligned from the host stars rotationaxis by 72deg plusmn 3deg and 73deg (+11deg -5deg) respectively From theseresults we limit KOI-89s causes of spin-orbit misalignment basedon three criteria agreement with KOI-89s fundamentalparameters the capability to cause extreme misalignment andconformance with mutually aligned planets We limit likely causesto star-disk binary interactions disk warping via planet-diskinteractions Kozai resonance planet-planet scattering or internalgravity waves in the convective interior of the star Our resultsdisfavor planet-embryo collisions chaotic evolution of stellar spinmagnetic torquing coplanar high-eccentricity migration andinclination resonance

Author(s) Johnathon Ahlers Jason W Barnes RoryBarnesInstitution(s) 1 University of Idaho 2 University ofWashingon

41706 ndash Predicting Precession Rates from SecularDynamics for Extra-solar Multi-planet SystemsConsidering the secular dynamics of multi-planet systems providessubstantial insight into the interactions between planets in thosesystems Secular interactions are those that dont involve knowing

where a planet is along its orbit and they dominate when planetsare not involved in mean motion resonances These interactionsexchange angular momentum among the planets evolving theireccentricities and inclinations To second order in the planetseccentricities and inclinations the eccentricity and inclinationperturbations are decoupled Given the right variable choice therelevant differential equations are linear and thus the eccentricityand inclination behaviors can be described as a sum of eigenmodesSince the underlying structure of the secular eigenmodes can becalculated using only the planets masses and semi-major axes onecan elucidate the eccentricity and inclination behavior of planets inexoplanet systems even without knowing the planets currenteccentricities and inclinations I have calculated both theeccentricity and inclination secular eigenmodes for the populationof known multi-planet systems whose planets have welldetermined masses and periods Using this catalog and assuming aGausian distribution for the eigenmode amplitudes and a uniformdistribution for the eigenmode phases I have predicted what rangeof precession rates the planets may have Generally planets thathave more than one eigenmode significantly contribute to theireccentricity (groupies) can have a wide range of possibleprecession rates while planets that are loners have a narrow rangeof possible precession rates One might have assumed that in anygiven system the planets with shorter periods would have fasterprecession rates However I show that in systems where theplanets suffer strong secular interactions this is not necessarily thecase

Author(s) Christa L Van LaerhovenInstitution(s) 1 Canadian Institute for Theoretical Astrophysics(CITA)

41707 ndash Collisional Cascade in a Debris Disk from anExternal PerturberThe study of circumstellar debris disks has often been coupled withthe study of planet formation A thermally warm debris disk (~300K) may indicate the presence of an exoplanet orbiting within andstirring the disk However there is another possible mechanism forheating a debris disk an external stellar-mass perturber excitingthe eccentricities and inclinations of the particles in a diskWe explore the consequences of an external perturber on theevolution of a debris disk The perturber excites the eccentricities ofthe particles in the disk via the Kozai-Lidov mechanism triggeringa collisional cascade among the planetesimals These collisionsproduce smaller dust grains and damp the particlesrsquo largereccentricitiesWe present the results of our study of a such a disk using secularanalysis and collisional N-body simulations We will discuss theconnections to observations of warm disks and the implications forplanet formation

Author(s) Erika Nesvold Smadar Naoz Laura Vican Benjamin Zuckerman Erika HolmbeckInstitution(s) 1 Department of Physics and Astronomy UCLA2 Department of Physics University of Notre Dame 3Department of Terrestrial Magnetism Carnegie Institution ofWashington

41708 ndash Detection and Characterization of ExtrasolarPlanets through Mean-Motion ResonancesSimulations of Hypothetical Debris DisksA planet orbiting interior or exterior to a debris disk may producesignatures in the disk that reveal the planets presence even if itremains undetected These features appear near mean-motionresonances and provide a powerful tool to not only detect unseenplanets in extra-solar systems but also help constrain their massand orbital parameters I will present results from simulations ofhypothetical debris disks both for interior and exterior resonancesshowing that gaps can be opened in cold debris disks away from theorbit of the planet and thus that not all disk gaps need contain aplanetary body The results allow us to constrain planet massessemi-major axes and eccentricities based on the locations andwidths of the gaps Moreover distinct features likely arising fromLindblad resonances are seen when the planet perturbing the disk

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has non-zero orbital eccentricity Finally I will present expressionsthat relate the planetary mass to the widths and locations of theobserved gaps

Author(s) Maryam Tabeshian Paul A WiegertInstitution(s) 1 Department of Physics and AstronomyUniversity of Western Ontario

41709 ndash Planetesimal dispersal during resonantcoupled migration of giant planetsWhen two giant planets during their early phases of evolution aretrapped in a mean motion resonance they may migrate outwardsAlong their path towards the outer regions of the disk they scatteraway most planetesimals within their gravitational reach When thegaseous disk is finally dispersed the leftover planetesimals may notbe numerous enough to break the resonance lock nor to damp apotential eccentricity build-up produced during the coupledmigration phase We performed N-body numerical simulationsshowing that the planetesimal scattering during the coupledoutward migration prevents a pair of planets like Jupiter andSaturn from breaking the 21 resonance once they reach theirpresent location In addition the planet eccentricities forced by theresonance lock remain large and are only slightlydamped before most of the surviving planetesimals are ejectedfrom the system

Author(s) Francesco Marzari Gennaro DAngeloInstitution(s) 1 LANL 2 Univ of Padova

418 ndash Origins of Planetary Systems41801 ndash Pebble Accretion and the Diversity ofPlanetary SystemsUnderstanding how planetary systems form and why they exhibitgreat diversity are key questions in planetary science Recentlyseveral studies of planet formation have focussed on a mechanismcalled ``pebble accretion Here mm-to-m size particles in aprotoplanetary disk are strongly affected by both gas drag andgravity during an encounter with a growing planet This cansubstantially increase the capture probability speeding upplanetary growth and providing a possible solution to thelong-standing problem of how gas-giant planets form within theshort lifetimes of protoplanetary disks (Lambrechts and Johansen2012 Astron Astrophys 544 A32) It has also been suggested thatpebble accretion can explain the profound difference between therocky inner planets and the gas-rich outer planets of the SolarSystem (Morbidelli et al 2015 Icarus 258 418) Here I will presentnew simulations of planet formation in an evolving protoplanetarydisk spanning both the regions in which rocky and gaseous planetsare likely to form The simulations cover the runaway oligarchicand gas-accretion phases of planetary growth and includeapproximate models for pebble growth and the formation ofasteroid sized planetesimals from pebbles Planetary growth ratesin these models are sensitive to the poorly-constrained propertiesof pebbles in a protoplanetary disk and also the properties of thegaseous disk itself especially the strength of turbulence Differentdisk and pebble properties lead to a wide range of outcomesincluding some cases resembling the Solar System and mayexplain the observed diversity of extrasolar planetary systems

Author(s) John E ChambersInstitution(s) 1 Carnegie Inst of Washington

41802 ndash Planetesimals embedded in a gaseous disc vsmean-motion resonancesWe study orbital evolution of km-sized planetesimals in a gaseousdisc with one or more embedded giant protoplanets Especially wefocus on the regions intersected by the inner mean-motionresonances with the innermost (Jovian) protoplanet eg 21 5283 31 The planetesimals orbiting in these regions are subject tocombined effects of aerodynamic and resonant perturbations Weaim to numerically investigate two possible outcomes of thisinterplay First stable resonant islands can exist (as in Chrenko et

al 2015) and may slow down or capture planetesimals as theyspiral sunward In such a case the resonances might serve asnatural barriers for the flux of planetesimals and locally acceleratethe accumulation of the solid materialSecond the resonances can overcome the damping effects of thegas and pump the eccentricities of the crossing planetesimals(Marzari amp Weidenschilling 2002) This process might generateeccentric orbits which lead to increased relative velocities withrespect to the nebular gas and crossing of non-resonant (circular)orbits The environment of the gaseous disc is simulated with theFARGO code (Masset 2000) which is a 2D Eulerian solver of thefluid equations with fast azimuthal advection We modified thecode so it can treat small planetesimals as test particles affected bythe respective aerodynamic dragAcknowledgements The work of OC and MB has been supportedby Charles University in Prague project GA UK No 1062214

Author(s) Ondrej Chrenko Miroslav BrozInstitution(s) 1 Institute of Astronomy Charles University inPrague

41803 ndash The Fragility of the Terrestrial PlanetsDuring a Giant Planet InstabilityMany features of the outer solar system are replicated in numericalsimulations if the giant planets undergo an orbital instability thatejects one or more ice giants During this instability the orbits ofJupiter and Saturn are believed to diverge crossing their 21 meanmotion resonance (MMR) and this resonance-crossing can excitethe orbits of the terrestrial planets Using a large ensemble ofnumerical simulations of this giant planet instability we directlymodel the evolution of the terrestrial planet orbits during thisprocess paying special attention to those systems that reproducethe basic features of the outer planets In systems that retain fourgiant planets and finish with Jupiter and Saturn beyond their 21MMR we find an 80-90 probability that at least one terrestrialplanet is lost Moreover most systems that manage to retain allfour terrestrial planets finish with terrestrial planet eccentricitiesand inclinations larger than the observed ones There is less than a20 chance that the terrestrial planet orbits will have a level ofexcitation comparable to the observed orbits If we factor in theprobability that the outer planetary orbits are well-replicated wefind a probability of 3 or less that the orbital architecture of theinner and outer planets are simultaneously reproduced in the samesystem These small probabilities raise the prospect that the giantplanet instability may have occurred before the terrestrial planetshad formed Such a scenario implies that the giant planet instabilityis not the source of the Late Heavy Bombardment and that theterrestrial planets completed their formation within the giantplanetsrsquo post-instability configuration

Author(s) Nathan A Kaib John E ChambersInstitution(s) 1 Carnegie Institution for Science 2 Universityof Oklahoma

41804 ndash On the Origin of the Kepler-36 SystemThe Kepler-36 system comprises two exoplanets an innerterrestrial super-Earth (45 M ) and an outer gaseoussub-Neptune (81 M ) Both planets are orbiting very close to theirhost star (012 and 013 AU away) and to each other Their orbitalperiods are in nearly a 76 ratio a mean-motion resonance that isnot usually populated Finally the inner planet is much denserthan Earth (75 gcm ) while the outer planet is substantially lessdense (089 gcm ) a surprise given the close proximity of theirorbitsWe examine origin scenarios for Kepler-36 featuring planetarymigration due to dissipative forces within the circumstellar gasdisk In our model the planets did not form in situ but rathermoved inwards through a region of smaller planetesimals andembryos We assume that the outer body formed beyond the frostline with significant gas accretion to account for its low densityThis sub-Neptune migrated inward and captured an embryo ofnegligible relative mass into a 21 orbital resonance Collisionsbetween this embryo and other bodies of similar mass broke theresonance and allowed the two planets to converge while the inner

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one grew in mass and densityUsing HNDrag an N-body code we have found several scenariosthat might explain the observations Although our successfulscenarios occur with low probability this is actually a strength sincefew known systems share the peculiarities of Kepler-36 Our modelexplains the main observed features of this system in the context ofstandard planetary formation theory

Author(s) Thomas Rimlinger Douglas Hamilton DerekRichardsonInstitution(s) 1 University of MD College Park

41805 ndash KOI2138 -- a Spin-Orbit Aligned IntermediatePeriod Super-EarthA planets formation and evolution are encoded in spin-orbitalignment -- the planets inclination relative to its stars equatorialplane While the solar systems spin-orbit aligned planets indicateour own relatively quiescent history many close-in giant planetsshow significant misalignment Some planets even orbitretrograde Hot Jupiters then have experienced fundamentallydifferent histories than we experienced here in the solar system Inthis presentation I will show a new determination of the spin-orbitalignment of 21 R exoplanet candidate KOI2138 KOI2138shows a gravity-darkened transit lightcurve that is consistent withspin-orbit alignment This measurement is important because theonly other super-Earth with an alignment determination (55 Cnc eorbit period 074 days) is misaligned With an orbital period of2355 days KOI2138 is far enough from its star to avoid tidal orbitevolution Therefore its orbit is likely primordial and hence it mayrepresent the tip of an iceberg of terrestrial spin-orbit alignedplanets that have histories that more closely resemble that of thesolar systems terrestrial planets

Author(s) Jason W BarnesInstitution(s) 1 University of Idaho

41806 ndash Sustained Accretion on Gas GiantsSurrounded by Low-Turbulence CircumplanetaryDisksGas giants more massive than Saturn acquire most of theirenvelope while surrounded by a circumplanetary disk (CPD) whichextends over a fraction of the planetrsquos Hill radius Akin tocircumstellar disks CPDs may be subject to MRI-driven turbulenceand contain low-turbulence regions ie dead zones It wassuggested that CPDs may inhibit sustained gas accretion thuslimiting planet growth because gas transport through a CPD maybe severely reduced by a dead zone a consequence at odds with thepresence of Jupiter-mass (and larger) planets We studied how anextended dead zone influences gas accretion on a Jupiter-massplanet using global 3D hydrodynamics calculations with meshrefinements The accretion flow from the circumstellar disk to theCPD is resolved locally at the length scale Rj Jupiters radius Thegas kinematic viscosity is assumed to be constant and the deadzone around the planet is modeled as a region of much lowerviscosity extending from ~Rj out to ~60Rj and off the mid-planefor a few CPD scale heights We obtain accretion rates onlymarginally smaller than those reported by eg DAngelo et al(2003) Bate et al (2003) Bodenheimer et al (2013) who appliedthe same constant kinematic viscosity everywhere including in theCPD As found by several previous studies (eg DrsquoAngelo et al2003 Bate et al 2003 Tanigawa et al 2012 Ayliffe and Bate 2012Gressel et al 2013 Szulaacutegyi et al 2014) the accretion flow does notproceed through the CPD mid-plane but rather at and above theCPD surface hence involving MRI-active regions (Turner et al2014) We conclude that the presence of a dead zone in a CPD doesnot inhibit gas accretion on a giant planet Sustained accretion inthe presence of a CPD is consistent not only with the formation ofJupiter but also with observed extrasolar planets more massivethan Jupiter We place these results in the context of the growthand migration of a pair of giant planets locked in the 21 meanmotion resonance

Author(s) Gennaro DAngelo Francesco MarzariInstitution(s) 1 NASA Ames Research Center 2 University ofPadova

419 ndash Marss Atmosphere41901 ndash Collision-Induced Dissociation CrossSections Relevant to Atmospheric Loss from MarsThe flow onto an atmosphere of the solar wind plasma a plasmatrapped in a planetary magnetic field or a local pick-up ion plasmaproduces chemistry heating and atmospheric loss Theseprocesses which affect its evolution are often lumped together asatmospheric sputtering (Johnson 1994) When the atmospherenear the exobase is atomic then laboratory data calculations orscaled models for the collision cross sections are usually availablefor use in Monte Carlo simulations of atmospheric sputteringHowever atmospheres on a number of planetary bodies havemolecules at the exobase and in the corona for which cross sectiondata is often not available Of particular interest are studies of theatmosphere of Mars in which there can be are significant levels ofCO2 and CO in the exobase region Here we present newcalculations using improved potential energy surfaces of collision-induced dissociation of incident O atoms (~10eV-1keV) formed byneutralization of pick-up O+ incident on CO and CO2 moleculesand compare their importance to our earlier estimates (egJohnson and Liu 1998 Johnson et al 2002) and discuss theirrelevance to simulations of atmospheric loss from Mars

Author(s) Hayley N Williamson Cathy Tully RobertJohnsonInstitution(s) 1 University of Virginia

41902 ndash Modeling Results on the Seasonal Influenceat the Martian ExosphereAnalysis of HST ACSSBC images of Mars in the far-ultraviolettaken in Oct-Nov 2007 and May-November 2014 indicate seasonalinfluence as a driving factor of the hydrogen corona as has beenreported earlier To derive the changes in number density andtemperature the data must be compared to a radiative transfermodel to simulate the resonantly scattered optically thick Lyman αemission from the exosphere of Mars This work presents detailson the modeling process used to analyze the data and thecorresponding uncertainties The escape flux is highly dependenton the characteristics of the martian exosphere like the exobasetemperature and number density of H atoms as well as thepresence or absence of a superthermal population of hydrogenatoms Detailed studies on the workings of the radiative transfermodel indicate degeneracy between temperature and numberdensity values that can fit the data Therefore it is difficult toaccurately determine the characteristics of the martian hydrogenexosphere without independent measurement of at least one of thevariables However HST observations have the advantage ofobserving a large portion of the dayside exosphere with intensityprofiles extending from altitudes of 700 - 30000 km giving a betterestimate of the best-fit temperature and density values whichcharacterize the martian exosphere under different seasonalconditions Comparisons of the latitudinal symmetry from the HSTimages indicate the exosphere to be symmetric beyond 25 martianradii due to the broad trajectories of atoms at high altitudes

Author(s) Dolon Bhattacharyya John Clarke Jean-LoupBertaux Jean-Yves Chaufray Majd MayyasiInstitution(s) 1 Boston University 2 LATMOS

41903 ndash Stationary Planetary Waves in the MarsWinter Atmosphere as seen by the Radio ScienceExperiment MaRS on Mars ExpressStationary (Rossby) Waves are excited by the interaction of thezonally varying topography with the strong eastward winter jetsThey lead to distinctive longitudinal temperature variations whichcontribute significantly to the asymmetry of the seasonal polar CO2ice caps and are also important for the dust redistribution in theplanetary atmosphere

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Radio Science profiles from the Mars Express Radio ScienceExperiment MaRS at northern and southern high latitudes areused to gain insight into winter stationary wave structures on bothhemispheresMars Global Surveyor (MGS) radio occultation measurements fromthe same season and year with their exceptionally goodlongitudinal and temporal coverage can be used to estimate theinfluence of transient eddies Transient waves are especiallyimportant in the northern winter hemisphereWave number 2 stationary waves driven by topography aredominant in the northern winter latitudes while the wave number 1wave is the most significant wave number during southern winterThe wave amplitudes peak around winter solstice on bothhemispheresRadio occultation measurements provide the unique opportunityto determine simultaneous measurements of temperature andgeopotential height structures Assuming geostrophic balancethese measurements can be used to determine meridional windsand eddy heat fluxes which provide further insight into thecontribution of stationary waves to the heat exchange between thepoles and the lower latitudes

Author(s) Silvia Tellmann Martin Paumltzold BerndHaumlusler Leonard G Tyler David P HinsonInstitution(s) 1 Department of Electrical Engineering StanfordUniversity 2 Institut fuumlr Raumfahrttechnik undWeltraumnutzung Universitaumlt der Bundeswehr Muumlnchen 3Rheinisches Institut fuumlr Umweltforschung (RIU) Department ofPlanetary Research

41904 ndash Traveling Waves in the northern hemisphereof Mars - Structure Variability and EnergeticsInvestigations of the variability structure and energetics oftraveling waves in the northern hemisphere of Mars wereconducted with the MarsWRF general circulation model Using asimple annually repeatable dust scenario the model reproducesthe general characteristics of the observed traveling wavesincluding major wave periods and thermal signatures of travelingwaves suppression of transient eddy activity near the surface atnorthern winter solstice and wave mode transitions among zonalwavenumber m = 1 2 and 3 eastward traveling waves near thesurface Simulated wave structures in the temperature field differfrom those in the geopotential field Wave energetics calculationsindicate a mixed baroclinic-barotropic nature for representativewave modes This is consistent with Barnes et al (1993) There is alarge contrast in wave energetics between the near surface andhigher altitudes as well as between the poleward and equatorwardside of the maximum eddy available potential energy at higheraltitudes The modeled transient eddies exhibit strong zonalvariations in kinetic energy and various energy transfer terms Inparticular the eddy kinetic energy for a time period dominated by am = 3 traveling wave shows local maxima in Acidalia Utopia andArcadia which are the origination locations of ldquoflushingrdquo duststorms The eddy kinetic energy for a time period transitioningfrom m = 2 to m = 3 traveling waves shows local maxima in Acidaliaand Utopia There are direct energy exchanges between thermaltides and traveling waves but the exchange rate is much slowerthan other major energetics terms When thermal tides areremoved from the MarsWRF simulation the amplitudes of m = 3traveling waves are greatly reduced In the meantime theisotherms of the northern baroclinic zone slope more towards thepole satisfying an empirical condition for weaker traveling wavesnear the surface However this change cannot fully explain thestrength of the simulated m = 3 traveling waves as both weak andoccasional strong m = 3 waves emerge from very similar zonalmean temperature structures

Author(s) Huiqun Wang Anthony D ToigoInstitution(s) 1 APL 2 SAO

41905 ndash Large-Scale Weather Disturbances in MarsrsquoSouthern ExtratropicsBetween late autumn and early spring Marsrsquo middle and highlatitudes within its atmosphere support strong mean thermal

gradients between the tropics and poles Observations from boththe Mars Global Surveyor (MGS) and Mars Reconnaissance Orbiter(MRO) indicate that this strong baroclinicity supports intenselarge-scale eastward traveling weather systems (ie transientsynoptic-period waves) These extratropical weather disturbancesare key components of the global circulation Such wave-likedisturbances act as agents in the transport of heat and momentumand generalized scalartracer quantities (eg atmospheric dustwater-vapor and ice clouds) The character of large-scale travelingextratropical synoptic-period disturbances in Mars southernhemisphere during late winter through early spring is investigatedusing a moderately high-resolution Mars global climate model(Mars GCM) This Mars GCM imposes interactively lifted andradiatively active dust based on a threshold value of the surfacestress The model exhibits a reasonable dust cycle (ie globallyaveraged a dustier atmosphere during southern spring andsummer occurs) Compared to their northern-hemispherecounterparts southern synoptic-period weather disturbances andaccompanying frontal waves have smaller meridional and zonalscales and are far less intense Influences of the zonallyasymmetric (ie east-west varying) topography on southernlarge-scale weather are examined Simulations that adapt Marsrsquo fulltopography compared to simulations that utilize synthetictopographies emulating key large-scale features of the southernmiddle latitudes indicate that Marsrsquo transient barotropicbarocliniceddies are highly influenced by the great impact basins of thishemisphere (eg Argyre and Hellas) The occurrence of a southernstorm zone in late winter and early spring appears to be anchoredto the western hemisphere via orographic influences from theTharsis highlands and the Argyre and Hellas impact basinsGeographically localized transient-wave activity diagnostics areconstructed that illuminate dynamical differences amongst thesimulations and these are presented

Author(s) Jeffery L Hollingsworth Melinda A KahreInstitution(s) 1 NASA Ames Research Center

41906 ndash The Mars Dust and Water CyclesInvestigating the Influence of Clouds on the VerticalDistribution and Meridional Transport of Dust andWaterThe dust and water cycles are critical to the current Martianclimate and they interact with each other through cloud formationDust modulates the thermal structure of the atmosphere and thusgreatly influences atmospheric circulation Clouds provide radiativeforcing and control the net hemispheric transport of water throughthe alteration of the vertical distributions of water and dust Recentadvancements in the quality and sophistication of both climatemodels and observations enable an increased understanding ofhow the coupling between the dust and water cycles (through cloudformation) impacts the dust and water cycles We focus here on theeffects of clouds on the vertical distributions of dust and water andhow those vertical distributions control the net meridionaltransport of water We utilize observations of temperature dustand water ice from the Mars Climate Sounder (MCS) on the MarsReconnaissance Orbiter (MRO) and the NASA ARC Mars GlobalClimate Model (MGCM) to show that the magnitude and nature ofthe hemispheric exchange of water during NH summer is sensitiveto the vertical structure of the simulated aphelion cloud beltFurther we investigate how clouds influence atmospherictemperatures and thus the vertical structure of the cloud belt Ourgoal is to isolate and understand the importance ofradiativedynamic feedbacks due to the physical processes involvedwith cloud formation and evolution on the current climate of Mars

Author(s) Melinda A Kahre Robert M Haberle Jeffery LHollingsworth Amanda S Brecht Richard A UrataInstitution(s) 1 BAER Institute 2 NASA Ames Research Center

41907 ndash In Situ Observations of Line-of-SightExtinction Reveals the Depth of the PlanetaryBoundary Layer within Gale Crater MarsImagers onboard the Mars Science Laboratory have been used toderive line-of-sight extinction coefficients within Gale Crater Mars

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The images in use have similar pointings and look at roughly thesame section of the north crater rim some 30 km away Theobservations are taken on average once every seven sols and havespanned more than an entire martian year Another longstandingand more frequent observation is one in which the total columnoptical depth above Gale Crater can be derived When comparingthe two datasets one can conclude that the air within the northernpart of the crater supports less dust per volume than the bulkatmosphere above the crater As such little to no mixing has beenobserved between the two air masses More recently line-of-sightextinction variations with height have allowed the depth of theplanetary boundary layer (PBL) to be examined by comparingmorning and noon-time imaging The top of the PBL can be seen asa change in the slope of the extinction Below this change of slopewe observe that the PBL is well mixed with near constantextinction The reduced extinction within the PBL may indicatethat in contrast to other Mars landing sites where mixing isimplicated in dust lifting that the relatively mild dynamics ofmixing at Gale contribute to clearing of the PBL by enhancing thedelivery of dust to the surface Above the PBL extinction increasesrapidly The PBL is typically seen to be shallower than the height ofthe crater rim some 2 km above the crater floor Not only was asuppressed PBL within Gale Crater predicted before landing thefact that extinction is seen to increase above the PBL provides moreevidence that the air mass above the crater initially supports moredust on average than the air lower down in the crater

Author(s) Casey A Moore John E Moores Mark TLemmon Jason Van BeekInstitution(s) 1 Malin Space Science Systems 2 Texas AampMUniversity 3 York University

41908 ndash Ice Cloud Optical Depth Mapping fromMRO-CRISM Multispectral DataThe Mars Reconnaissance Orbiter (MRO) CompactReconnaissance Imaging Spectrometer for Mars (CRISM) multi-spectral mapping data are a reduced spectral sampling mapping setusing only 72 of its 545 channels This reduction allowed forgreater spatial coverage and the creation of nearly complete mapsafter several sols of orbits Using data from late 2006 through early2008 I have created 6 such maps in order to measure ice cloudoptical depth as a function of position for each of them Opticaldepth is retrieved using a DISORT-based radiative transfer code[1]One of the inputs for the code is surface reflectance which is notknown at each point a priori but instead is fit from a linearcombination of surface endmember spectramdashthe endmembercoefficients for each endmember along with dust and ice opticaldepth are adjustable model parameters that are varied until theRMS error between model and data is a minimum Surface spectralendmembers are recovered through a combination of principalcomponent analysis (PCA) and target transformation (TT) whichfirst reduces the dimensionality of the data (from 72 to 4) and thencreates a data cloud in this space of possible potential endmembersderived from best fits of a spectral library [2ndash4] The actualendmembers are chosen from extrema of this candidate cloudI will present six ice cloud optical depth maps made using thistechnique with a 3-endmember surface model[1] Wolff M J personal communication[2] Klassen D R (2013) AASDPS Abstracts 45 31305[3] Klassen D R (2014) LPI Contributions 1791 1384[4] Klassen D R (2014) The Fifth International Workshop on theMars Atmosphere 2303

Author(s) David R KlassenInstitution(s) 1 Rowan Univ

41909 ndash Detections and Sensitive Upper Limits forMethane and Related Trace Gases on Mars during2003-2014 and planned extensions in 2016Five groups report methane detections on Mars all results suggestlocal release and high temporal variability [1-7] Our team searchedfor CH on many dates and seasons and detected it on severaldates [1 9 10] TLS (Curiosity rover) reported methane upperlimits [6] and then detections [7] that were consistent in size with

earlier reports and that also showed rapid modulation of CHabundance[8] argued that absorption features assigned to Mars CH by [1]might instead be weak lines of terrestrial CH If not properlyremoved terrestrial CH signatures would appear on the bluewing of terrestrial CH even when Mars is red-shifted ndash but theydo not (Fig S6 of [1]) demonstrating that terrestrial signatureswere correctly removed [9] demonstrated that including thedependence of δ CH with altitude did not affect the residualfeatures nor did taking δ CH as zero Were δ CH importantits omission would have overemphasized the depth of CHterrestrial absorption introducing emission features in the residualspectra [1] However the residual features are seen in absorptionestablishing their origin as non-terrestrial ndash [8] now agrees withthis viewWe later reported results for multiple organic gases (CH CH OHH CO C H C H C H ) hydroperoxyl (HO ) three nitriles(N O NH HCN) and two chlorinated species (HCl CH Cl) [9]Most of these species cannot be detected with current space assetsowing to instrumental limitations (eg spectral resolving power)However the high resolution infrared spectrometers (NOMADACS) on ExoMars 2016 (Trace Gas Orbiter) will beginmeasurements in late 2016 In solar occultation TGO sensitivitieswill far exceed prior capabilitiesWe published detailed hemispheric maps of H O and HDO onMars inferring the size of a lost early ocean [10] In 2016 we planto acquire 3-D spatial maps of HDO and H O with ALMA andimproved maps of organics with iSHELLNASA-IRTFReferences [1] Mumma et al Sci09 [2] Formisano et al Sci04[3] Krasnopolsky et al Icar04 [4] Fonti and Marzo AampA10 [5]Krasnopolsky Icar12 [6] Webster et al Sci13 [7] Webster et alSci15 [8] Zahnle et al Icar11 [9] Villanueva et al Icar13 [10]Villanueva et al Sci15

Author(s) Michael J Mumma Geronimo L Villanueva Robert E NovakInstitution(s) 1 Iona College 2 NASAs GSFC

41910 ndash Longitudinal Maps of Marsrsquo O (singlet Delta)Emission for L =725deg and L =880degWe report longitudinal maps of the O (singlet Delta) emission rate(a tracer for high-altitude ozone) taken at two seasonal pointsL =725deg (03 April 2010) and L =880deg (10 February 2014) usingCSHELL at NASArsquos IRTF On these dates the entrance slit of thespectrometer was positioned E-W on Mars centered at thesub-Earth point but on 10 Feb 2014 additional spectra were takenwith the slit positioned 3 arc seconds North of the sub-Earth pointOn both dates spectralspatial images (near 127 microns) wererepeatedly taken over a four-hour period Spectral extracts fromthese images were taken at 06 arcsec intervals along the slit Amodel consisting of solar continuum with Fraunhofer linestwo-way transmission through Marsrsquo atmosphere and a one-waytransmission through the Earthrsquos atmosphere was used to isolateand analyze individual spectral lines Boltzmann analysis of theselines yielded the rotational temperature (~175 K) that was used todetermine the total emission rate from the measured linesThe slit on 03 Apr 2010 crossed the morning terminator yieldingmeasurements between 0600-1400 Local Time on 10 Feb 2014the slit went through the evening terminator (1000-1800 LT) Forboth dates data were taken over a four-hour interval in UT Whendisplayed versus local time the extracted emission rates revealsimilar patterns of growth before mid-day and of decline beforesunset regardless of surface topography The measured emissionrates that peak after noon local time depend on the angles to bothSun and Earth The post-noon emission rates (10 Feb 2014) varywith latitude because they depend on the location of thehygropauseThis work was partially funded by grants from NASAs PlanetaryAstronomy Program (344-32-51-96) NASArsquos AstrobiologyProgram (344-53-51) and the NSF-RUI Program (AST-805540)We thank the administration and staff of the NASA-IRTF forawarding observing times and coordinating our observations

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Author(s) Robert E Novak Michael J Mumma GeronimoL VillanuevaInstitution(s) 1 Iona College 2 NASA-GSFC

41911 ndash Diurnal and Interannual Variation inAbsorption Lines of Isotopic Carbon Dioxide in MarsAtmosphereGroundbased observations of Mars in 2003 2007 2012 and 2014have detected transitions of carbon dioxide containing the stableminor isotopes of oxygen and carbon as well as the primaryisotopes using the ultrahigh resolution spectrometer HIPWAC atthe NASA Infrared Telescope Facility The most well characterizedminor isotope is O-18 due to strong lines and observationalopportunities The average estimated O-18O-16 isotope ratio isroughly consistent with other in situ and remote spectroscopicmeasurements but demonstrates an additional feature in that theretrieved ratio appears to increase with greater ground surfacetemperature These conclusions primarily come from analyzing asubset of the 2007 data Additional observations have beenacquired over a broad range of local time and meridional position toevaluate variability with respect to ground surface temperatureThese additional observations include one run of measurementswith C-13 These observations can be compared to local in situmeasurements by the Curiosity rover to narrow the uncertainty inabsolute isotope ratio and extend isotopic measurements to otherregions and seasons on Mars The relative abundance of carbondioxide heavy isotopes on Mars is central to estimating theprimordial atmospheric inventory on Mars Preferential freeze-distillation of heavy isotopes means that any measurement of theisotope ratio can be only a lower limit on heavy isotope enrichmentdue to past and current loss to space

Author(s) Timothy A Livengood Theodor Kostiuk TilakHewagama John R Kolasinski Wade G HenningInstitution(s) 1 CRESSTUMDGSFC 2 NASA GSFC 3University of Maryland

41912 ndash The search for active release of volcanic gaseson MarsThe study of planetary atmospheres by means of spectroscopy isimportant for understanding their origin and evolution Thepresence of short-lived trace gases in the martian atmospherewould imply recent production for example by ongoing geologicactivity On Earth sulfur dioxide (SO ) sulfur monoxide (SO) andhydrogen sulfide (H S) are the main sulfur-bearing gases releasedduring volcanic outgassing Carbonyl sulfide (OCS) also releasedfrom some volcanoes on Earth (eg Erebus and Nyiragongo)could be formed by reactions involving SO or H S inside magmachambers We carried out the first ground-basedsemi-simultaneous multi-band and multi-species search for suchgases above the Tharsis and Syrtis volcanic regions on Mars Thesubmillimeter search extended between 23 November 2011 and 13May 2012 which corresponded to Marsrsquo mid Northern Spring andearly Northern Summer seasons (Ls = 34ndash110deg) The strongsubmillimeter rotational transitions of SO SO and H S weretargeted using the high-resolution heterodyne receiver (akaBarney) on the Caltech Submillimeter Observatory We reachedsensitivities sufficient to detect a volcanic release on Mars that is4 of the SO released continuously from Kilauea volcano inHawaii or 5 that of the Masaya volcano in Nicaragua Theinfrared search covered OCS in its combination band (ν +ν ) at342 μm at two successive Mars years during Marsrsquo late NorthernSpring and mid Northern Summer seasons spanning L = 43 andL = 147 The targeted volcanic districts were observed during thetwo intervals 14 Dec 2011 to 6 Jan 2012 in the first year and 30May 2014 to 16 June 2014 in the second year using the highresolution infrared spectrometer (CSHELL) on NASArsquos InfraredTelescope Facility (NASAIRTF) We will present our results anddiscuss their implications for current volcanic outgassing activityon the red planet We gratefully acknowledge support from theNASA Planetary Astronomy Program under NASA contractNNH14CK55B that supported AK and AT RTOP 344-32-07 andNASArsquos Astrobiology Program (RTOP 344-53-51) that supportedMJM and GLV

Author(s) Alain Khayat Geronimo Villanueva MichaelMumma Alan TokunagaInstitution(s) 1 Catholic University of America 2 Institute forAstronomy 3 NASA Goddard Spaceflight Center

41913 ndash Solar wind Mars interaction during theMAVEN Deep Dip campaigns multi-fluid MHDsimulations based upon the SWIA NGIMS and MAGmeasurementsThe 3-D Mars multi-fluid Block Adaptive Tree Solar-wind RoeUpwind Scheme (BATS-R-US) MHD code is used to study the solarwind interaction with the Martian upper atmosphere during theMAVEN Deep Dip campaigns MAVEN made the firstcomprehensive measurements of Martian thermosphere andionosphere composition structure and variability at altitudesdown to ~130 km in the subsolar region during the second of itsDeep Dip campaigns MAVEN will start its fourth Deep Dipcampaign this September and a large quantity of useful data will bereturned for this study as well In this study we adopt the MAVENmeasurements as the multi-fluid MHD inputs The estimated solarwind density and velocity the estimated interplanetary magneticfield (IMF) and the exactly measured neutral atmosphere profileare taken from the SWIA MAG and NGIMS instrumentsrespectively We will compare the calculated ionosphere ionprofiles with the NGIMS measurements In the meantime we willshow the calculations of the global ion escape rates based uponactual measured neutral atmosphere profiles during the MAVENDeep Dip campaigns

Author(s) Chuanfei Dong Stephen W Bougher YingjuanMa Gabor Toth Shannon M Curry Andrew F Nagy JasperS Halekas Janet G Luhmann Paul Mahaffy Mehdi Benna Jack E P Connerney Jared Espley David L Mitchell David ABrain Bruce M JakoskyInstitution(s) 1 NASA Goddard Space Flight Center 2University of California 3 University of California 4 Universityof Colorado 5 University of Iowa 6 University of Michigan

41914 ndash He Bulge Detection by MAVEN Neutral Gasand Ion Mass Spectrometer (NGIMS) in the UpperAtmosphere of MarsStudies of the Venusian atmospheres have demonstrated enhancedHe densities at high latitudes and on the night-side detections Todetermine if Mars has a similar enhanced He lsquobulgersquo in the sameregion we compared several periapsis passes from night to daysideThe first six weeks of the MAVEN prime mission had periapsis athigh latitudes on the night-side followed by the next three monthsat mid latitudes on the dayside moving to low latitudes on thenight-side In addition to its normal orbit which has a periapsis ofapproximately 150 km MAVEN conducts a few deep dip orbitswhere the spacecraft has a periapsis closer to 125km The first deepdip was at dusk at mid latitudes the second at noon at the equatorwith the third going from dawn to night in the southernhemisphere Initial analysis of the Neutral Gas and Ion MassSpectrometer (NGIMS) closed source data from all orbits with goodpointing revealed an enhanced He density on the night-side orbitsand a decreased He density on the dayside This enhancement ofHe demonstrates a bulge at Mars that will continue to be exploredover the course of the mission

Author(s) Meredith K Elrod Paul R Mahaffy Roger Yelle Shane Stone Mehdi Benna Bruce JakowskiInstitution(s) 1 NASA Goddard SFC 2 University of Arizona3 University of Colorado Boulder

41915 ndash New Observations of Molecular Nitrogen bythe Imaging Ultraviolet Spectrograph on MAVENThe Martian ultraviolet dayglow provides information on the basicstate of the Martian upper atmosphere The Imaging UltravioletSpectrograph (IUVS) on NASArsquos Mars Atmosphere and VolatileEvolution (MAVEN) mission has observed Mars at mid and far-UVwavelengths since its arrival in September 2014 In this work wedescribe a linear regression method used to extract components ofUV spectra from IUVS limb observations and focus in particular on

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molecular nitrogen (N ) photoelectron excited emissions Weidentify N Lyman-Birge-Hopfield (LBH) emissions for the firsttime at Mars and we also confirm the tentative identification of NVegard-Kaplan (VK) emissions We compare observed VK andLBH limb radiance profiles to model results between 90 and 210km Finally we compare retrieved N density profiles to generalcirculation (GCM) model results Contrary to earlier analyses usingother satellite data that indicated N densities were a factor of threeless than predictions we find that N abundances exceed GCMresults by about a factor of two at 130 km but are in agreement at150 km

Author(s) Michael H Stevens J S Evans Nicholas MSchneider AIF Stewart Justin Deighan Sonal K Jain Matteo MJ Crismani Arnaud Stiepen Michael S Chaffin William E McClintock Greg M Holsclaw Franck Lefevre Franck Montmessin Daniel Y Lo John T Clarke Stephen WBougher Bruce M JakoskyInstitution(s) 1 Center for Space Physics Boston University 2Computational Physics Inc 3 Department of Climate and SpaceSciences and Engineering University of Michigan 4 Laboratoryfor Atmospheric and Space Physics 5 LATMOSCNRS 6 Lunarand Planetary Laboratory University of Arizona 7 Space ScienceDivision Naval Research Laboratory

41916 ndash Two Types of Aurora on Mars as Observed byMAVENs Imaging UltraViolet SpectrographThe Imaging UltraViolet Spectrograph (IUVS) on the MAVENspacecraft has detected two distinct types of auroral emission onMars First we report the discovery of a low altitude diffuse auroraspanning much of Marsrsquo northern hemisphere coincident with asolar energetic particle outburst IUVS observed northerly latitudesduring late December 2014 detecting auroral emission in virtuallyall nightside observations for ~5 days spanning virtually allgeographic longitudes The vertical profile showed emission downto ~70 km altitude (1 microbar) deeper than confirmed at anyother planet The onset and duration of emission coincide with theobserved arrival of solar energetic particles up to 200 keVprecipitating directly and deeply into the atmosphere Preliminarymodeling of the precipitation energy deposition and spectral lineemission yields good matches to the observations Theseobservations represent a new class of planetary auroras producedin the Martian middle atmosphere Given minimal magnetic fieldsover most of the planet Mars is likely to exhibit aurora moreglobally than EarthSecond we confirm the existence of small patches of discreteaurora near crustal magnetic fields in Mars southern hemisphereas observed previously by SPICAM on Mars Express (Bertaux et alNature 435 790-794 (2005)) IUVS observed southern latitudes inJuly and August 2015 detecting discrete auroral emission in ~1of suitable observations Limb scans resolved both vertically andalong-slit indicate this type of auroral emission was patchy on thescale of ~40 km and located at higher altitudes ~140 km Thehigher altitudes imply a lower energy of precipitating particles Themix of spectral emissions also differed signficiantly from the diffuseaurora indicating different excitation and quenching processesWe will discuss the observed properties of the aurora andassociated charged particle precipitation as well as the broaderimplications of this high-energy deposition into Mars atmopshere

Author(s) Nicholas M Schneider J Deighan SK Jain A Stiepen D Larson DL Mitchell CO Lee R Lillis DBrain WE McClintock MS Chaffin M Crismani GMHolsclaw BM Jakosky C Mazelle JS Evans AIFStewart MH Stevens JT Clarke F Montmessin FLefevre D LoInstitution(s) 1 Center for Space Physics Boston University 2CNRS Institut de Recherche en Astrophysique et PlaneacutetologieFrance 3 Computational Physics Inc 4 LASP Univ ofColorado 5 LATMOSIPSL 6 Space Science Division NavalResearch Laboratory 7 Space Sciences Lab University ofCalifornia at Berkeley

41917 ndash Combined analysis of Far UV and Mid UV

spectra obtained by the MAVEN IUVS instrument in aStellar Occultation ModeIn this presentation we will focus on the results obtained by theImaging Ultraviolet Spectrograph (IUVS) onboard the MarsAtmosphere and Volatile and Evolution (MAVEN) mission whileperforming stellar occultations observations In the IUVSwavelength range CO possesses a distinct and broad signatureshortward of 200 nanometers which allows one to retrieve COconcentration and subsequently to deduce atmospheric pressureand temperature profiles from 30 to 150 km of altitude (uppertroposphere up to the thermosphere) as well as the concentrationof other atmospheric consitituents (cloudsaerosols ozone andmolecular oxygen) The occultation technique relies on thedetermination of atmospheric transmission at various altitudesabove the surface Only relative measurements are needed to inferspecies abundances and thus the method is self-calibratedThe ratio of spectra taken through (close to Mars) and outside (farfrom Mars) the atmosphere gives an atmospheric transmission ateach altitude If any absorbing orand scattering species is presentalong the optical path photons are lost and resulting transmissionsare lower than 1 The sampling rate yields a vertical resolutiontypically greater than 3 km on the vertical For Mars the soundedregion inside which a quantity of atmospheric constituents can bederived lies generally between 20 and 150 km depending on theatmospheric state (dust loading) The compiled dataset has alreadyyielded a variety of results showing high concentrations of ozonein the deep polar night as well as the detection of a highly elevatedaerosol layer potentially made of CO ice

Author(s) Franck Montmessin Hannes Groeller GaeacutetanLacombe Nicholas M Schneider Roger Yelle Ian Stewart Justin Deighan John Clarke Franck Lefevre Lucio Baggio William E McClintock Gregory M Holsclaw Bruce MJakoskyInstitution(s) 1 Boston University 2 CNRS LATMOS 3 LASP4 LPL

41918 ndash MAVENIUVS Observations of the GaseousPerturbation from Comet C2013 A1 (Siding Spring)on Mars and its Constant Metallic Ion LayerThe close passage of comet C2013 A1 (Siding Spring) by Marsafforded the newly arrived Mars Atmosphere and VolatileEvolutioN (MAVEN) mission the opportunity to observe acometary perturbation to the upper atmosphere The mostdramatic atmospheric effect was the ablation of cometary dust thatproduced a transient metallic ion layer near 120 km higher thanthe predicted (90 km) constant metallic ion layer from sporadicdust ablation due to the extreme relative velocity of the comet (56kms) Additionally cometary gases such as H O CO and theirdaughter species delivered mass and energy to the upperatmosphere where the temperature at 150 km was predicted toincrease by 30 KThe Imaging Ultraviolet Spectrograph (IUVS) on MAVEN takeslimb scans at periapse to construct altitude profiles of variousultraviolet species Using a Multiple Linear Regression (MLR)technique to extract spectral features we analyze the observationsof the perturbed atmosphere to determine whether the gaseousmass and energy deposition is distinguishable within typicalatmospheric variation Furthermore we use all subsequent daysideobservations to identify the metallic ion layer represented by thepresence of Mg and compare these observations with a robustnumerical model of ablation CAMBOD (Chemical AblationModel)

Author(s) Matteo Michael James Crismani NicholasSchneider Sonal Jain John Plane Justin DeighanInstitution(s) 1 CU Boulder 2 Laboratory for Atmospheric andSpace Physics 3 University of Leeds

41919 ndash The ExoMars 2016 missionThe ExoMars programme is a joint activity by the European SpaceAgency (ESA) and ROSCOSMOS Russia It consists of theExoMars 2016 mission with the Trace Gas Orbiter TGO and theEntry Descent and Landing Demonstrator Schiaparelli and the

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Exomars 2018 mission which carries a lander and a roverThe TGO scientific payload consists of four instruments These areACS and NOMAD both infrared spectrometers for atmosphericmeasurements in solar occultation mode and in nadir modeCASSIS a multichannel camera with stereo imaging capability andFREND an epithermal neutron detector for search of subsurfacehydrogen ESA is providing the TGO spacecraft and the SchiaparelliLander demonstrator and two of the TGO instruments andROSCOSMOS is providing the launcher and the other two TGOinstrumentsAfter the arrival of the ExoMars 2018 mission at the surface ofMars the TGO will handle the communication between the Earthand the Rover and lander through its UHF communication systemThe 2016 mission will be launched by a Russian Proton rocket fromBaikonur in January 2016 and will arrive at Mars in October thesame year This presentation will cover a description of the 2016mission including the spacecraft its payload and science and therelated plans for scientific operations and measurements

Author(s) Haringkan Svedhem Jorge Vago Rolf de GrootInstitution(s) 1 ESAESTEC

41920 ndash Self- and CO -broadened line shapeparameters for infrared bands of HDOKnowledge of CO -broadened HDO line widths and theirtemperature dependence is required to interpret infrared spectra ofthe atmospheres of Mars and Venus However this information iscurrently absent in most spectroscopic databases We haveanalyzed nine high-resolution high signal-to-noise spectra of HDOand HDO+CO mixtures to obtain broadening coefficients andother line shape parameters for transitions of the ν and νvibrational bands located at 713 and 270 μm respectively The gassamples were prepared by mixing equal amounts of high-puritydistilled H O and 99 enriched D O The spectra were recorded atdifferent temperatures (255-296 K) using a 2038 cm long coolablecell [1] installed in the sample compartment of the BrukerIFS125HR Fourier transform spectrometer at the Jet PropulsionLaboratory in Pasadena CA The retrieved HDO spectroscopicparameters include line positions intensities self- andCO -broadened half-width and pressure-induced shift coefficientsand the temperature dependences for CO broadening Thesespectroscopic parameters were obtained by simultaneousmultispectrum fitting [2] of the same interval in all nine spectra Anon-Voigt line shape with speed dependence was applied Linemixing was also observed for several transition pairs Preliminaryresults compare well with the few other measurements reported inthe literature[1] K Sung et al J Mol Spectrosc 162 124-134 (2010)[2] D C Benner et al J Quant Spectrosc Radiat Transfer 53705-721 (1995)The research performed at the College of William and Mary wassupported by NASArsquos Mars Fundamental Research Program(Grant NNX13AG66G) The research at Jet Propulsion LaboratoryCalifornia Institute of Technology Connecticut College LangleyResearch Center and Goddard Space Flight Center was conductedunder contracts and cooperative agreements with the NationalAeronautics and Space Administration RRG is pleased toacknowledge support of this study by the National ScienceFoundation through Grant No AGS-1156862

Author(s) Mary-Ann H Smith V Malathy Devi D ChrisBenner Keeyoon Sung Arlan W Mantz Robert R Gamache Geronimo L VillanuevaInstitution(s) 1 Connecticut College 2 Jet PropulsionLaboratory California Institute of Technology 3 NASA GoddardSpace Flight Center 4 NASA Langley Research Center 5 TheCollege of William and Mary 6 University of Massachusetts

41921 ndash Simulating Helium abundances in theMartian upper atmosphere using 1-D and 3-D modelsChemically inert species such as Helium serve as an excellenttracer for the interplay between turbulent eddy diffusive processesand molecular diffusive processes Using species such as Heliumwe can effectively constrain the altitude of the homopausemdashor the

transition from the well-mixed lower atmosphere to themass-separation characteristic of the upper atmosphere In thisstudy we will use the Mars Global Ionosphere-ThermosphereModel (M-GITM) to examine the impacts of altering the turbulentdiffusion coefficient (eddy diffusion coefficient) on the simulatedabundances of Helium Using data obtained by the Neutral Gas andIon Mass Spectrometer (NGIMS) onboard the Mars Atmosphereand Volatile Evolution (MAVEN) mission as a benchmark we canexamine what possible values for eddy diffusion in thethermosphere are most likely present in Marsrsquos upperatmospheremdashin other words we can assess where the meanhomopause altitude is most likely located during the MAVENmission Furthermore we will compare and contrast the resultsobtained when using a strictly classical 1-D treatment of theproblem with a more complete coupled global 3-D treatment of theMartian atmosphere

Author(s) Jared M Bell S W Bougher Paul Mahaffy Meredith ElrodInstitution(s) 1 Goddard Space Flight Center 2 NationalInstitute of Aerospace 3 University of Michigan

41922 ndash Boundary location of Mars nightsideionospheric plasma in term of the electron densityPhoto-ionized Mars atmosphere is forming an ionosphere andshielding the solar wind with creating barriers of bow shock Insidethe bow shock ionospheric plasma interact with solar wind plasmaand result different boundaries A question is how far theionospheric plasma can stand off the solar windOn the dayside in-situ data set from Mars magnetosphere missionsoften observed the sharp gradient of the thermal plasma flux andion composition change as well as the drop off of the magneticfluctuation simultaneously as a outer boundary of the ionosphericplasma and an obstacle to the solar wind Several models haveconstructed the shape of the boundary based on the statisticalobservations [eg Trotignon et al 2006 Edberg et al 2008]On the nightside plasma instrument onboard Phobos 2 observedthe particles and magnetic field characteristics similar to thedayside However the number of data is still too few to understandthe general location of boundaries We will present thecharacteristics of the nightside magnetospheric boundary region interm of the electron density MAVEN Langmuir probemeasurement (LPW) can estimate the electron density using thespacecraft environment As MAVEN pass from the bow shock andsheath region into the magnetosphere the electron density oftenshow a sharp gradient (the density jumps two orders of magnitudesin a few seconds) Comparing this to the data from particleinstrument the sharp electron density gradient was oftenassociated with the transition of the characteristic energy of ionsSeveral hundreds of boundaries crossing by MAVEN allow us toinvestigate the statistical view of the boundary We searched for alarge electron density gradient as an indicator of the plasmaboundary to identify the location of the ionosphericsolar windplasma boundary The results show that the many of the nightsideboundaries locates close to the tail region of Mars forming ellipticalshape of boundary We will provide the empirical model of thisboundary location and discuss the influence of solar wind

Author(s) Michiko W Morooka Laila Andersson BobErgun Christopher Fowler Adam Woodson Tristan Weber Greg Delory David Andrews Niklas Edberg Anders Eriksson David Michell Jack Connerney Jacob Gruesbeck JasperHalekasInstitution(s) 1 Department of Physics and AstronomyUniversity of Iowa 2 Laboratory for Atmospheric and SpacePhysics University of Colorado at Boulder 3 NASAGSFC 4Space Sciences Laboratory amp Center for Integrative PlanetarySciences University of California Berkeley 5 Space SciencesLaboratory University of Calfolnia Berkeley 6 Swedish Instituteof Space Physics

41923 ndash Examining Traveling Waves in MarsAtmosphere ReanalysesSynoptic-scale eddies (traveling waves) are a key feature of the

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variability of Mars atmosphere weather in the extratropics and arelinked to the initiation of dust storms Mars reanalyses whichcombine satellite observations with simulations from a Mars GlobalClimate Model (MGCM) provide a four-dimensional picture of theevolution of these waves in terms of temperature winds pressureand aerosol fields The Ensemble Mars Atmosphere ReanalysisSystem (EMARS) has created multiple years of Mars weather mapsthrough the assimilation of Thermal Emission Spectrometer (TES)and Mars Climate Sounder (MCS) temperature profiles using theensemble Kalman filter and the GFDL MGCM We investigate therobustness of the synoptic eddies to changes in the aerosol fieldsmodel parameters data assimilation system design andobservation dataset (TES vs MCS) We examine the evolution ofwavenumber regimes their seasonal evolution and interannualvariability Finally reanalysis fields are combined with spacecraftvisible imagery (eg MGS Mars Orbital Camera) demonstrating thelink between meteorological fields (temperature pressure andwind) and dust fronts

Author(s) Steven J Greybush R John WilsonInstitution(s) 1 GFDL 2 The Pennsylvania State University

41924 ndash Abiotic production of NO3 in the atmosphereof Early MarsRecent CuriositySAM measurements of Martian sediments haveshown the presence of NO3 trapped in the samples The ratio ofnitrate to perchlorate has been suggested to be an indicator forhabitability (Stern et al 2015) However the efficiency of theproduction of nitrate in the atmosphere has never been studied forthe case of the active young Sun To evaluate the effect of theabiotic production of nitrates we apply our 1D atmosphericphotochemical collisional model for the nitrogen-rich and CO2atmosphere of early Mars and calculate the production rate of NO3mediated by the precipitation of energetic particles associated withthe coronal mass ejections from the young SunWe propose a method to check the hypothesis of the abioticproduction if the production is driven by the precipitatingparticles then the magnetic shielding would reduce the NO3production at the equator Thus samples collected at high latitudesshould contain greater concentration of nitrates if the weatheringdid not homogenize it

Author(s) Guillaume Gronoff vladimir airapetian EricHebrardInstitution(s) 1 NASA GSFC 2 SSAI Nasa LaRC

41925 ndash New Approaches in estimating Dust DevilParameters Trajectories and Populations fromSingle-Station Measurements on Mars and EarthA Monte-Carlo modeling approach (Lorenz J Atm Sci 2014)using a power law population function and empirical correlationsbetween diameter and longevity can be used to reconcile single-station pressure records of vortex close-approaches with visualcounts of dust devils and Large Eddy Simulations (LES) That worksuggests that on Earth the populations can be reconciled ifdust-lifting occurs with a typical threshold corresponding to corepressure drop of 08 mb a little higher than the ~03 mb estimatedin laboratory experiments A similar analysis can be conducted atMars The highest vortex production rates in LES indicated fromfield encounters and extrapolated from visual counts appear to beof the order of 1000 per km2 per dayRecent field experiments at a playa near Goldstone CA (Lorenz etal Bulletin of the Seismological Society of America in press) showthat dust devils cause a ground tilt due to the negative pressureload of the vortex on the elastic ground that can be detected with abroadband seismometer like that on InSight Dust devils thereforecan serve as a lsquoseismic sourcersquo to characterize the shallowsubsurfaceObservations of the InSight landing area in Elysium by Reiss andLorenz (Icarus submitted) show that dust devil trails areabundant but smaller in diameter than those at Gusev This mayindicate a shallower Planetary Boundary Layer (PBL) at this siteand season Fenton and Lorenz (Icarus 2015) found that observeddust devil height and spacing in Amazonis relates to the PBL

thicknessQuantitative assessment of dust devil effects (eg electrical andmagnetic signatures) requires knowledge of encounter geometrynotably miss distance A recent heuristic approach has beendeveloped (Lorenz Icarus submitted) to fit an analytic vortexmodel to pressure windspeed and direction histories to recoverthis geometry Some ambiguities exist but can be constrained withcamera images andor the azimuth history estimated from seismicdata

Author(s) Ralph LorenzInstitution(s) 1 JHUAPL

41926 ndash Response of the Martian inducedmagnetosphere to variations in solar forcingSolar forcing and compression of Mars induced magnetospheremay play an important role in oxygen loss at Mars via enhancedionization and heating of the lower atmosphere and in theformation of ambipolar electric fields in the upper atmosphereSteep electron temperature gradients in the upper atmosphere canproduce strong ambipolar fields at altitudes where collisions areinfrequent leading to increased outflow of O and O Suchenhanced escape has been observed in simulations of Marsrsquoionosphere where the ambipolar field was artificially varied to studyits influence on escape It is important therefore to understandhow solar wind forcing modulates electron density- andtemperature-versus-altitude profiles in Mars ionosphereDuring the first five days of May 2015 MAVENrsquos Langmuir Probeand Waves Instrument (LPW) observed variations in the locationand extent of the transition region between the shocked solar windand the Martian ionosphere in the dayside hemisphere Solar winddensities and velocities derived from MAVENrsquos Solar Wind IonAnalyzer (SWIA) indicate that the solar wind dynamic pressure wasalso highly variable during this period In this work we investigatehow the shapes of the electron density- and temperature-versus-altitude profiles measured by LPW depend on the location andextent of the transition region as determined from Solar WindElectron Analyzer (SWEA) spectra and on solar wind forcing asdetermined from SWIA and MAVEN Magnetometer (MAG)measurements over this five-day period

Author(s) Adam Woodson Tristan Weber LailaAndersson Robert Ergun David Andrews Tiffany Chamandy John Connerny Greg Delory Anders Eriksson ChristopherFowler Jasper Halekas Paul Mahaffy David Mitchell Michiko MorookaInstitution(s) 1 CU Boulder Laboratory for Atmospheric andSpace Physics 2 NASA Goddard Space Flight Center 3 SwedishInstitute of Space Physics 4 U Iowa Department of Physics andAstronomy 5 UC Berkely Space Sciences Laboratory

420 ndash Mars Surface and Interior42001 ndash First results of the PlanetFour CitizenScience projectPlanetFour (httpwwwplanetfourorg) is a Citizen Science projectabout analyzing surface images from the south pole of Mars Mainobjectives are studying the surface atmosphere interactions at thepole especially during the local spring CO2 gas jets that are createdby basal sublimation of the seasonal CO2 ice layer deposit fine dustinto the atmosphere and coarser regolith on top of the ice sheet inform of fan-shaped albedo features The fine dust that entered theatmosphere is believed to have an important effect on theatmospheric temperature profile The seasonal removal of regolithover many years results in topographical features calledaraneiform These are dendritic troughs that connect to a commoncenter Their constant modification represents ongoing change inthe surface topography of Mars todayA further objective is to map the orientations of the regolithdeposits These orientations are controlled by the local winds thatexisted at the time of jet eruption Repeated surface observationsconstrain the time of eruption and are therefore able to providewind data points for atmospheric meso-scale simulations

2 1

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The image data used in the PlanetFour project comes from theHiRISE camera of the Mars Reconnaissance Orbiter Planet Fourcitizens are asked to identify and outline fans in the presented tilesWe cluster the resulting markings into final locations using theDBScan clustering algorithm after which the object coordinates areback-projected into latitude and longitude coordinates with astandard ISIS image calibration pipelineOutcomes are catalogs of object locations estimated sizes and winddirections With these catalogs we study the activity over time perregion compare these activity time-series between seasons andcompare the strength of observed activity between different regionsaround the pole The derived wind directions are used to improveatmospheric meso-scale simulations at Marsrsquo south pole which ispart of an ongoing NASA SSW project We will present results fromthe first publication of the PlanetFour project

Author(s) Klaus-Michael Aye Meg Schwamb GannaPortyankina Candice J HansenInstitution(s) 1 Institute of Astronomy amp AstrophysicsAcademia Sinica 2 Planetary Science Institute 3 University ofColorado Boulder

42002 ndash Mineralogical Stratigraphy of GangesChasma MarsMarsrsquo Valles Marineris canyon system reveals a several-kilometerdeep stratigraphies sequence that extends thousands of kilometersthis sequence thus represents a unique opportunity to exploremillions of years of volcanic and aqueous activity in this region ofMars Of particular interest to the study of both volcanic andaqueous processes is Ganges Chasma which lies on thenortheastern boundary of the Valles Marineris canyon system onMars The canyon likely opened during the Late Noachian to EarlyHesperian modifying previously emplaced Noachian-aged volcanicplains During formation volcanic activity from the nearby Tharsisshield complex emplaced olivine-rich dikes throughout the regionAfter formation sulfate-bearing Interior Layered Deposits (ILDs)were emplaced in Ganges and many other chasmata throughoutthe Valles Marineris system Today Ganges reveals a complexstratigraphy including wide-spread olivine-rich sands hydratedminerals on the plateaus surrounding the canyon and a centralsulfate-rich ILD Here we present updated stratigraphies ofGanges Chasma using new data from the CompactReconnaissance Imaging Spectrometer for Mars (CRISM) andsynthesizing it with previous data sets Olivine sands are tracedback to source outcrops on the canyon floor and new outcrops ofhydrated minerals on the surrounding plateau are identified andmapped Recently reported spectroscopic signatures of ankeriteand smectite in the chasm are assessed and new olivine-richoutcrops identified and mapped Understanding the stratigraphy ofGanges Chasma will help us compare stratigraphies among thechasmata of the Valles Marineris further building ourunderstanding of the geologic history of this large region of Mars

Author(s) Selby Cull-Hearth M Caroline ClarkInstitution(s) 1 Bryn Mawr College

42003 ndash ChemCam at Gale Crater Highlights andDiscoveries from Three Years of ChemicalMeasurements on MarsChemCam has undertaken a detailed chemical investigation of therocks and soils at Gale crater over the last three years with over sixthousand separate geochemical measurements Recentrecalibration of the ChemCam data using a new library of gt350geochemical standards has enabled increased elemental accuraciesover a wider compositional range The increased accuracycombined with ChemCamrsquos small spot size allows for the chemistryof mineral end members including feldspars high silica oxide richgrains to be identified ChemCam has observed both sedimentaryand igneous compositions Igneous compositions are generallypresent in conglomerates and in float rocks Compositions show awide range of igneous chemistry ranging from basaltic to feldsparrich assemblagesSedimentary rocks have a wide range of compositions reflectingboth differences in chemical source regions and in depositional and

diagenetic histories The ldquoSheepbedrdquo mudstones cluster aroundMartian average crustal compositions The ldquoKimberleyrdquo outcropshowed enhanced potassium reaching concentrations up to ~6 wtK O More recent observations in the Murray Formation at thebase of Mt Sharp reveal mudstones that are lower in magnesiumand higher in silica and aluminum than the more basalticmudstones previously investigated Extremely high silica (75-85wt) deposits have also been identified The high silicaobservations were associated with increased TiO While theMurray mudstones are generally low in magnesium localenhancements in magnesium have also been noted associated withresistant facies in the outcrop Chemical trends also indicate thatiron oxide phases may also be present as cements Sandstone facieswith a mafic composition are also present Veins in the unit alsoshow a wide range of compositions indicating fluid chemistries richin calcium sulfate fluorine magnesium and iron were presentVein chemistry could be the result of distinct fluids migratingthrough from a distance with a pre-established chemical signaturefluids locally evolved from water rock interactions or both Thusthe chemical relationships between the Pahrump bedrock and theveinsrsquo chemistry can be used to constrain the origin of the fluids

Author(s) Diana L Blaney Roger Wiens SylvestreMaurice Olivier Gasnault Ryan Anderson John Bridges Nathan Bridges Samuel Clegg Benton Clark BethanyEhlmann Melinda D Dyar Martin Fisk Raymond Francis Cecile Fabre Olivier Forni Jens Frydenvang JefferyJohnson Nina Lanza Richard Leveille Jeremie Lasue Laetitia Le Deit Nicholas Mangold Noureddine Melikechi Marion Nachon Horton Newsom Valerie Payre WilliamRapin Violane Sautter David Vaniman John Grotzinger Ashwin Vasavad Joy CrispInstitution(s) 1 Aplied Physics Laboratory 2 CaliforniaInstitute of Technology 3 Deleware State University 4 John HChapman Space Centre 5 Los Alamos National Laboratory 6Mount Holyoke College 7 Museum National dHistorie Naturelle8 NASA Jet Propulsion Laboratory California Institute ofTechnology 9 Oregon State University 10 Planetary ScienceInstitute 11 Space Science Institute 12 Universiteacute Paul SabatierUPS-OMP Institute de Recherche en Astrophysique et Planetologie(IRAP) 13 University Lorraine 14 University of Copenhagen 15University of Leicester 16 University of New Mexico 17Univertisty of Nantes 18 US Geologic Survey

42004 ndash Sub-surface gas flow in porous bodiesGas flow within porous media is of importance for various bodies inthe Solar System It occurs within the Martian soil might besignificant in the porous interiors of comets and also within dustyplanetesimals in the Solar Nebula In regimes of low atmosphericpressure thermal creep leads to an efficient gas flux if temperaturegradients are present eg by solar insolation This flow can lead toerosion or supports the exchange of volatiles within a porous bodyExperiments showed that this gas flux dominates over diffusive gastransport under Martian conditions with gas velocities on the orderof cms Results from the Rosetta spacecraft suggest that eolianprocesses occur on comets which might be related to thermal creepgas flow Here we present new results of microgravity experimentson a thermally induced gas flow Gas velocities and theirdependence on the atmospheric pressure for different gases(Helium and air) are studied as well as the influence of thegeometry of the pores

Author(s) Jens Teiser Mathias Schywek Caroline de Beule Gerhard WurmInstitution(s) 1 University Duisburg-Essen

42005 ndash Permeability Barrier Generation in theMartian LithospherePermeability barriers develop when a magma produced in theinterior of a planet rises into the cooler lithosphere and crystallizesmore rapidly than the lithosphere can deform (Sparks andParmentier 1991) Crystallization products may then clog theporous network in which melt is propagating reducing thepermeability to almost zero ie forming a permeability barrier

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155

Subsequent melts cannot cross the barrier Permeability barriershave been useful to explain variations in crustal thickness atmid-ocean ridges on Earth (Magde et al 1997 Hebert andMonteacutesi 2011 Monteacutesi et al 2011) We explore here under whatconditions permeability barriers may form on MarsWe use the MELTS thermodynamic calculator (Ghiorso and Sack1995 Ghiorso et al 2002 Asimow et al 2004) in conjunctionwith estimated Martian mantle compositions (Morgan and Anders1979 Waumlnke and Dreibus 1994 Lodders and Fegley 1997Sanloup et al 1999 Taylor 2013) to model the formation ofpermeability barriers in the lithosphere of Mars In order torepresent potential past and present conditions of Mars we varythe lithospheric thickness mantle potential temperature (heatflux) oxygen fugacity and water contentOur results show that permeability layers can develop in thethermal boundary layer of the simulated Martian lithosphere if themantle potential temperature is higher than ~1500degC The variousMartian mantle compositions yield barriers in the same locationsunder matching variable conditions There is no significantdifference in barrier location over the range of accepted Martianoxygen fugacity values Water content is the most significantinfluence on barrier development as it reduces the temperature ofcrystallization allowing melt to rise further into the lithosphereOur lower temperature and thicker lithosphere model runs whichare likely the most similar to modern Mars show no permeabilitybarrier generation Losing the possibility of having a permeabilitybarrier likely changed the character of volcanism on Mars maybepreventing the formation of new localized volcanic edifices in theAmazonian

Author(s) Joe Schools Laurent MonteacutesiInstitution(s) 1 University of Maryland

42006 ndash New estimates of the Martian landers androvers coordinates by combining Doppler data andtopography modelWe propose here a new method to determine the three coordinatesof a spacecraft landed on Mars with a high accuracy as early as thevery beginning of the mission The method consists of determiningfirst the in-equatorial plane coordinates with Doppler data only andthen inferring the Z-coordinate (along the polar axis) using theMOLA topography model The method is applied to several landedmissions providing good estimate of the Z-coordinate of Vikinglander 1 Pathfinder and Spirit but failing to improve the Z ofOpportunity and Viking lander 2 Finally the method is applied inthe InSight landing ellipse showing the high probability to getInSightrsquos Z coordinate with a precision better than 10m after only acouple of days of observations

Author(s) Sebastien Le MaistreInstitution(s) 1 Jet Propulsion Laboratory

500 ndash Comet 67PC-G -- Nucleus50001 ndash Mass Density and Composition of theNucleus 67PChuryumov-GerasimenkoCometary nuclei consist mostly of dust and water ice but theinternal structure of a comet nucleus is essentially unknown Bulkproperties such as mass volume (size and shape) and particularlythe density must be known for constraining its internal structureThe radio science experiment RSI on the Rosetta spacecraft derivedthe mass and the gravity field of comet 67PChuryumov-Gerasimenko at distances varying between 100 km and 10 km andtogether with the current best estimates of the volume by theOSIRIS camera the bulk density of the nucleus A model of theinternal structure is derived from the information of two shapemodels by comparing observed and theoretical gravity coefficientsThe comet nucleus appears to be a body of low mass low densityand high porosity with approximately four times more dust than iceby mass and 15 times more dust than ice by volume

Author(s) Martin Paetzold Tom Andert Matthias Hahn Sami W Asmar Jean-Pierre Barriot Michael K Bird BerndHaumlusler Kerstin Peter Silvia A Tellmann Eberhard Gruumln Paul Weissman Holger Sierks Laurent Jorda FrankPreusker Frank ScholtenInstitution(s) 1 Max-Planck-Institute for Nuclear Physics 2Institut fuumlr Planetenforschung DLR-Berlin-Adlershof 3 JetPropulsion Laboratory Caltech 4 Laboratoire dAstrophysique deMarseille 5 Max-Planck-Institut fuumlr Sonnensystemforschung 6Rheinisches Institut fuumlr Umweltforschung an der Universitaumlt zuKoumlln 7 Universitaumlt der Bundeswehr Muumlnchen 8 Universite de laPolynesie Francaise

50002 ndash MIRO Observations of subsurfacetemperatures of the nucleus of 67PChuryumov-GerasimenkoObservations of the nucleus of 67PChuryumov-Gerasimenko inthe millimeter-wave continuum have been obtained by theMicrowave Instrument for the Rosetta Orbiter (MIRO) We presentpre-perihelion data obtained at wavelengths of 05 mm and 16 mmduring August 2014-July 2015 over a range of heliocentric distancebetween 362 and 125 AU The data are fit to simple models of thenucleus thermal emission in order to characterize the observedbehavior and make quantitative estimates of important physicalparameters including thermal inertia and absorption properties atthe MIRO wavelengths MIRO brightness temperatures on theirregular surface of 67PC-G are strongly affected by the local solarillumination conditions and there is a strong latitudinaldependence of the mean brightness temperature as a result of theseasonal orientation of the comets rotation axis with respect to theSun The MIRO emission exhibits strong diurnal variations whichindicate that it arises from within the thermally varying layer in theupper centimeters of the surface The data are quantitativelyconsistent with very low thermal inertia values between 10-30 JK m s with the 05 mm emission arising from 1 cm beneaththe surface and the 16 mm emission from a depth of 4 cm TheMIRO brightness temperatures are also affected by the sublimationof ice at or beneath the surface and provide a valuable constraint ondistribution of the water production from the nucleus

Author(s) F Peter Schloerb Stephen Keihm Paul vonAllmen Mathieu Choukroun Emmanuel Lellouch CedricLeyrat Samuel Gulkis Mark HofstadterInstitution(s) 1 JPL 2 LESIA-Observatoire de Paris 3 Univof Massachusetts

50003 ndash Meter-scale thermal contraction crackpolygons on comet 67PChuryumov-GerasimenkoSince August 2014 high spatial resolution images of the nucleus ofcomet 67PChuryumov-Gerasimenko have been acquired by theOSIRIS camera onboard Rosetta enabling to identify meter-scalefeatures on the surface (Thomas et al 2015 El-Maary et al 2015)Here we report on the detection and characterization of thermalcontraction polygons We have identified more than 6000 polygonson 67P using OSIRIS images with a spatial resolution down to 16mpixel They are observed in consolidated terrains from flatterrains to steep terrains such as cliffs and pit walls The size ofpolygons is in the range 1 ndash 10 m with a mean value of 3 mPolygons detected on 67P show morphologies with an elevatedcenter Polygons are known to form on Mars and Earth when thethermal stress of the surface icy materials exceeds their tensilestrength therefore forming fractures (Lachenbruch 1962Mangold 2005 Marchant amp Head 2007) The size shape andspatial distribution of polygons across the surface provideconstraints on their formation and evolution processes thesub-surface water ice content the thermal history of the surfaceand the mechanical properties of the surface material (eg Mellonet al 2008 Levy et al 2011)

1 1

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156

Author(s) Anne-Theacuteregravese Auger Mohamed RamyEl-Maarry Olivier Groussin Laurent Jorda Sylvain Bouley Antoine Seacutejourneacute Claire Capanna Sebastian Houmlfner HolgerSierksInstitution(s) 1 Aix-Marseille Universiteacute LaboratoiredAstrophysique de Marseille 2 Laboratoire GEOPS 3Max-Planck-Institut fuumlr Sonnensystemforschung 4Physikalisches Institut University of Bern

50004 ndash Using quantitative analysis to understandthe current and past physical processes that sculptedthe Philae landing siteThe CIVA cameras onboard PHILAE provided the first ever in situimages of the surface of a comet (Bibring et al Science 2015) Thepanorama acquired by CIVA at the landing site on the 67P cometreveals a rough terrain dominated by fractures and agglomerates ofconsolidated materials While the composition of these materials isunknown they provide unique structures to constrain theconditions prevailing at the surface of a comet A quantitativeanalysis of the microscopic structures (grains that look like pebblesand fractures) will be presented The pebble size distribution will becompared to the size distribution of other cometary materials suchas boulders at the touchdown site (Mottola et al Science 2015)boulders surrounding the landing site (Lucchetti et al AampAsubmitted) gt7m sized boulders globally distributed on the comet(Pajola et al AampA 2015) grains collected by the COSIMAexperiment onboard Rosetta (Langevin et al JGR submitted) aswell as population of grains remotely observed in coma and jets ofother comets The nature of the pebbles will be then discussed inrelation to both endogenic and exogenic processes that couldexplain their formation The fractures exhibit two different sizedistributions that are correlated to the texture of the landscapeAmong different physical processes we will evaluate whetherthermal fatigue induced by diurnal temperature variations (Delboet al Nature 2014) could be a mechanism of surficialfragmentation

Author(s) Francois Poulet Alice Lucchetti Jean-PierreBibring Yves Langevin John Carter Marco Delbo PascalEng Brigitte Gondet Laurent Jorda Steacutephane Le Moueacutelic Stefano Mottola Ceacutedric Pilorget Mathieu Vincendon GabrieleCremoneseInstitution(s) 1 University of Padova 2 DLR 3 InstitutdAstrophysique Spatiale 4 LPG-Universiteacute de NantesCNRS 5Observatoire de Marseille 6 UNS-CNRS-Observatoire de la CotedAzur

50005 ndash Temporal morphological changes at thesurface of comet 67PChuryumov-GerasimenkoA key scientific question to understand how comets work andwhether they still contain pristine materials at or near their surfaceis to understand how the nucleus is changing with time and towhich extent activity modifies its surface Rosetta which has beenorbiting comet 67PChuryumov-Gerasimenko since August 2014offers a unique opportunity to tackle this fundamental questionHere we report on temporal morphological changes detected onthe surface of the nucleus of comet 67P by the OSIRIS camerasChanges have been detected in several regions and in particular inthe Imhotep region where they are visible in the form of roundishfeatures that are growing in size from a given location in apreferential direction Terrains bluer than the surroundings appearduring changes suggesting the presence of (water) ice exposed onthe surface

Author(s) Olivier Groussin H Sierks C Barbieri PLamy R Rodrigo D Koschny H Rickman H U KellerInstitution(s) 1 Aix Marseille Universiteacute CNRS LAM(Laboratoire dAstrophysique de Marseille) UMR 7326 2 Centrode Astrobiologia (INTA-CSIC) 3 Department of Physics andAstronomy Padova University 4 Department of Physics andAstronomy Uppsala University 5 Institute of PlanetaryResearch DLR 6 Max-Planck-Institut fuumlrSonnensystemforschung 7 Scientific Support Office EuropeanSpace Agency

50006 ndash The 67P nucleus composition and temporalvariations observed by the OSIRIS cameras onboardRosettaSince August 2014 the comet 67PChuryumov-Gerasimenko hasbeen mapped by the NAC and WAC cameras of the OSIRIS imagingsystem in the 250-1000 nm wavelength range OSIRIS got themost detailed maps at the highest spatial resolution of a cometnucleus surface Here we report on the colors andspectrophotometry of the whole 67P nucleus from images acquiredsince the first Rosetta bound orbits in August 2014 up to the cometperihelion passage Globally the nucleus shows a red spectralbehavior and it has spectrophotometric properties similar to thoseof bare cometary nuclei of primitive D-type asteroids such usJupiter Trojans and of the moderately red Transneptunians Noclear absorption bands have been identified yet in the UV-VIS-NIRrange except for a potential absorption centered at 290 nmpossibly due to SO ice The nucleus shows an important phasereddening with disk-averaged spectral slopes increasing from11(100 nm) to 16(100 nm) in the 13-54deg phase angle rangeOn the basis of the spectral slope we identified three differentgroups of regions characterized by a low medium and highspectral slope respectively The three groups are distributedeverywhere on the nucleus with no evident distinction betweenthe two lobes of the comet The comet southern hemisphere thathas been observed by Rosetta since April 2015 shows a lack ofspectrally red regions associated to the absence of wide spreadsmooth or dust covered terrains Several local bright and spectrallyblue patches have been identified on the nucleus and attributed toexposed water ice on the surface In particular we observed big (gt1500 m ) bright ice rich areas in the southern hemisphere whichcompletely sublimated in a few weeks We see evidence of verybright patches in the NUV-blue region close to the morningshadows that are compatible with the presence of frostsices Thesepatches disappear when fully illuminated by the Sun indicating thatimportant processes of sublimation and recondensation of volatilesare taking place on the nucleus

Author(s) Sonia Fornasier Maria Antonietta Barucci Clement Feller Prasanna JD Deshapriya Antoine Pommerol Luisa Lara Nilda Oklay Mike AHearn Bjorn Davidsson Davide Perna Holger SierksInstitution(s) 1 Department for Astronomy University ofMaryland 2 Department of Physics and Astronomy 3 IAA-CSIC4 LESIA-Observatoire de Paris CNRS Univ Paris Diderot UnivPierre et Marie Curie 5 Max-Planck-Institut fuumlrSonnensystemforschung 6 Physikalisches Institut Univ of Berna

50007 ndash Variegation of active regions on comet67PChuryumov-GerasimenkoSince Rosetta spacecraftrsquos arrival to the comet 67P the OSIRISscientific imager (Optical Spectroscopic and Infrared RemoteImaging System Keller et al 2007) is successfully observing thenucleus with high spatial resolution in the 250-1000 nm rangethanks to set of 26 dedicated filtersWhile 67P has a typical red spectral slope the active areas tend todisplay bluer spectra (Sierks et al 2015 Fornasier et al 2015) Weperformed a spectral analysis of the active areas and derivedspectral characteristics of them possibly indicating the presence ofmaterial enriched in volatilesThe lsquoactivity thresholdsrsquo spectral method (Oklay et al 2015) is usedfor the identification of the active areas In most cases areasdetected with this technique have been later on confirmed as activesources (Lara et al 2015 Lin et al 2015 Vincent et al 2015) bydirect detection of dust jets This technique is therefore able toidentify currently active areas but also predicts which regions ofthe surface are likely to become activated once they receive enoughinsolationAcknowledgements OSIRIS was built by a consortium led by theMax-Planck-Institut fuumlr Sonnensystemforschung GoumlttingenGermany in collaboration with CISAS University of Padova Italythe Laboratoire dAstrophysique de Marseille France the Institutode Astrofisica de Andalucia CSIC Granada Spain the ScientificSupport Office of the European Space Agency Noordwijk TheNetherlands the Instituto Nacional de Tecnica Aeroespacial

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Madrid Spain the Universidad Politechnica de Madrid Spain theDepartment of Physics and Astronomy of Uppsala UniversitySweden and the Institut fuumlr Datentechnik undKommunikationsnetze der Technischen Universitaumlt BraunschweigGermany We thank the Rosetta Science Ground Segment at ESACthe Rosetta Mission Operations Centre at ESOC and the RosettaProject at ESTEC for their outstanding work enabling the sciencereturn of the Rosetta MissionKeller et al 2007 Space Sci Rev 128 433Sierks et al 2015 Science 3471Fornasier et al 2015 AampA published onlineLara et al 2015 AampA published onlineLin et al 2015 AampA published onlineVincent et al 2015 AampA submittedOklay et al 2015 in preparation

Author(s) Nilda Oklay Jean-Baptiste Vincent SoniaFornasier Maurizio Pajola Sebastien Besse Luisa M Lara Maria Antonietta Barucci Stefano Mottola Holger Sierks Antoine Pommerol Nafiseh Masoumzadeh Monica Lazzarin Frank Scholten Frank Preusker Ian HallInstitution(s) 1 CISAS 2 DLR 3 ESA 4 IAA-CSIC 5 LESIA6 MPS 7 Physikalisches Institut Universitaumlt Bern

50008 ndash 67PCG morphological units and VIS-IRspectral classes a RosettaVIRTIS-M perspectiveVIRTIS-M the 025-51 microm imaging spectrometer on Rosetta(Coradini et al 2007) has mapped the surface of 67PCG nucleussince July 2014 from a wide range of distances Spectral analysis ofglobal scale data indicate that the nucleus presents differentterrains uniformly covered by a very dark (Ciarniello et al 2015)and dehydrated organic-rich material (Capaccioni et al 2015) Themorphological units identified so far (Thomas et al 2015El-Maarry et al 2015) include dust-covered brittle materialsregions (like Ash Maat) exposed material regions (Seth)large-scale depressions (like Hatmehit Aten Nut) smooth terrainsunits (like Hapi Anubis Imhotep) and consolidated surfaces (likeHathor Anuket Aker Apis Khepry Bastet Maftet) For each ofthese regions average VIRTIS-M spectra were derived with the aimto explore possible connections between morphology and spectralproperties Photometric correction (Ciarniello et al 2015) thermalemission removal in the 35-5 micron range and georeferencinghave been applied to IF data in order to derive spectral indicatorseg VIS-IR spectral slopes their crossing wavelength (CW) and the32 microm organic material bandrsquos depth (BD) suitable to identify andmap compositional variations Our analysis shows that smoothterrains have the lower slopes in VIS (lt17E-3 1microm) and IR(04E-3 1microm) CW=075 microm and BD=8-12 Intermediate VISslope=17-19E-3 1microm and higher BD=10-128 are typical ofconsolidated surfaces some dust covered regions and Seth wherethe maximum BD=13 has been observed Large-scaledepressions and Imhotep are redder with a VIS slope of 19-21E-31microm CW at 085-09 microm and BD=8-11 The minimum VIS-IRslopes are observed above the Hapi in agreement with thepresence of water ice sublimation and recondensation processesobserved by VIRTIS in this region (De Sanctis et al 2015)Authors acknowledge ASI CNES DLR and NASA financialsupportReferences-Coradini et al SSR 28 529-559 2007-Ciarniello et al AampA in press-Capaccioni et al Science 347 aaa0628 1-4 2015-Thomas et al Science 347 aaa0440 1-6 2015-El-Marry et al AampA in press-De Sanctis et al Nature in press

Author(s) Gianrico Filacchione Fabrizio Capaccioni Mauro Ciarniello Andrea Raponi Maria Cristina De Sanctis Federico Tosi Giuseppe Piccioni Priscilla Cerroni MariaTeresa Capria Ernesto Palomba Andrea Longobardo Alessandra Migliorini Stephane Erard Gabriele Arnold Dominique Bockelee-Morvan Cedric Leyrat Bernard Schmitt Eric Quirico Antonella Barucci Thomas B McCord KatrinStephan David KappelInstitution(s) 1 DLR 2 INAF-IAPS 3 LESIA Obs Paris 4 TheBear Fight Institute 5 Univ Grenoble Alpes CNRS IPAG

50009 ndash Comet 67PChuryumov-GerasimenkoNon-Gravitational Forces Based on its Detailed ShapeNon-gravitational forces caused by sublimation on a cometarynucleus influence its orbital parameters and its rotationalproperties Based on thermal models and rough estimates of thenucleus shape properties such as its mass and density can bederived [1 2] The uncertainty of the nucleus shape influences thequality of the results Changes of the angular momentum of thenucleus rotation are more strongly influenced by details of theshape and surface The long term observations of the nucleus ofcomet 67PChuryumov-Gerasimenko by OSIRIS [3] during therendezvous with ESArsquos Rosetta spacecraft result in a very detailedshape model [3] We use a shape model with gt 10 facets tosimulate the distributed forces due to sublimation and to calculatetheir exerted torques The determination of the overall activity andits spatial and timely distribution over the nucleus remains a majorchallenge Early observations revealed that the rotation period hadchanged from its last perihelion passage in 2009 [4] The detailedshape model along with thermal modeling makes it possible tocalculate the diurnal activity of the facets [6 7] The net torqueintegrated over the whole surface causes a change in the angularmomentum We also calculate the forces acting on the motion ofthe nucleus This can be monitored by determinations of thespacecraft positions during the Rosetta mission We will compareour results with the traditional approach to calculate thenon-gravitational forces [8][1 2] Davidsson B J R amp Gutieacuterrez P J Icarus 168 392 2004Icarus 176 453 2005[3] H U Keller C Barbieri P Lamy H Rickman R RodrigoK-P Wenzel H Sierks M ArsquoHearn F Angrilli M Angulo et alSSR 128 (1-4) 433ndash506 2007[4] Preusker F Scholten F Matz K-D et al Astronomy ampAstrophysics accepted 2015[5] S Mottola S Lowry C Snodgrass P Lamy I Toth et al AampA569 L2 Sept 2014[6] H U Keller S Mottola B Davidsson S Schroumlder Y SkorovE Kuumlhrt et al AampA in press[7] H U Keller S Mottola Y V Skorov and L Jorda Astronomyand Astrophysics Letter 2015[8] B G Marsden Z Sekanina and D K Yeomans AstronomicalJournal 78 211 Mar 1973

Author(s) Horst Uwe Keller Stefano Mottola YuriSkorov Bjoumlrn Davidsson Pedro Gutieacuterrez Laurent Jorda Lucie MaquetInstitution(s) 1 Aix Marseille Universiteacute CNRS LAM 2Department of Physics and Astronomy Uppsala University 3Deutsches Zentrum fuumlr Luft- und Raumfahrt (DLR) Institut fuumlrPlanetenforschung Asteroiden und Kometen 4 Instituto deAstrofiacutesica de Andaluciacutea (CSIC) 5 Max-Planck-Institut fuumlrSonnensystemforschung 6 Scientific Support Office EuropeanSpace Astronomy CentreESA

501 ndash Extrasolar Planets Discovery andDynamics50101 ndash Discovery and follow-up of 51 Eri b adirectly-imaged Jupiter-like exoplanet and status ofthe GPIES campaignDirectly detecting thermal emission from young extrasolar planetsallows measurement of their atmospheric composition gravity andluminosity which is influenced by their formation mechanism The

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6

158

Gemini Planet Imager Exoplanet Survey (GPIES) is targeting 600young nearby stars using the GPI instrument The star 51 Eridani(51 Eri) was chosen as an early target for the survey due to its youthand proximity We discovered a planet orbiting the ~20 Myr-oldbeta Pic moving group member star 51 Eridani at a projectedseparation of 13 astronomical units (Macintosh et al Science2015) Near-infrared observations show a spectrum with strongmethane and water vapor absorption Modeling of the spectra andphotometry yields a luminosity of LL =16-40 times 10 and aneffective temperature of 600-750 K For this age and luminosityldquohot-startrdquo formation models indicate a mass twice that of JupiterThis planet also has a sufficiently low luminosity to be the firstdirectly imaged exoplanet to be consistent with the cold-start coreaccretion process that may have formed JupiterFollow-up observations scheduled in Fall 2015 will allow us toconstrain the orbit of this exoplanet and derive more informationon its atmosphere These new data and additional interestingtargets will be presented and discussedSupported by grants from the National Science FoundationAST-1411868 (BM KF JP AR) AST-0909188 and 1313718 (JRGPK RDR JW) AST-1313718 (MPF and GD) and AST-1405505Supported by grants from NASA NNX14AJ80G (BM FM EN MP)NNH15AZ591 (DS MM) NNX15AD95G (JRG PK) NNX11AD21G(JRG PK) and NNH11ZDA001N (SM RP) JR RD and DLacknowledge support from the Fonds de recherche du QuebecPortions of this work were performed under the auspices of theUS Department of Energy by Lawrence Livermore NationalLaboratory under Contract DE-AC52-07NA27344

Author(s) Franck Marchis Eric L Nielsen Sarah Blunt Julien Rameau Travis Barman Robert J De Rosa QuinnKonopacky Mark S Marley Christian Marois LaurentPueyo Abhijith Rajan Jason J Wang Bruce Macintosh James R GrahamInstitution(s) 1 Kavli Institute for Particle Astrophysics andCosmology Stanford University 2 Center for Astrophysics andSpace Sciences University of California 3 Department ofAstronomy UC Berkeley 4 Institut de Recherche sur lesExoplanegravetes Deacutepartment de Physique Universiteacute de Montreacuteal 5Lunar and Planetary Laboratory University of Arizona 6 NASAAmes Research Center MS 245-3 7 National Research Council ofCanada Herzberg 8 School of Earth and Space ExplorationArizona State University 9 SETI Institute 10 Space TelescopeScience Institute

50102 ndash The SuPerPiG search for short period planetsin the K2 datasetPlanets with orbital periods of less than a day present realchallenges to theories of planet formation and evolution and yetnumerous objects with periods as short as a few hours have beenfound So close to their host stars that some are activelydisintegrating these planets origins remain unclear and evenmodified models for planet formation and evolution withsignificant inward migration have trouble accounting for theirperiods They thus provide an important probe of the innermostregion of the protoplanetary disk We report on the ongoing effortsof the Short-Period Planets Group (SuPerPiGhttpwwwastrojackcomresearchsuperpig) to find additionalshort-period planets in the K2 Mission using the light curveproducts produced by the Vanderburg and Johnson k2sff pipeline(Vanderburg amp Johnson 2014 httpsarchivestscieduprepdsk2sff) Preliminary results from Campaign 2 includingaccounting for a 6-hour pseudo transit signal introduced by theKepler spacecraft thruster re-pointing will be presented

Author(s) Elisabeth R Adams Brian JacksonInstitution(s) 1 Boise State University 2 Planetary ScienceInstitute

50103 ndash A Quantitative Criterion for Defining PlanetsThe IAU definition of planet needs improvement because it isneither quantitative nor general The current definition appliesonly to solar system bodies and does not allow for the classificationof exoplanets The current definition can also be misunderstood or

misconstrued because of its qualitative nature (eg has clearedthe neighbourhood around its orbit)A simple metric can be used to determine whether a planet orexoplanet can clear its orbital zone during a characteristic timescale such as the lifetime of the host star on the main sequenceThis criterion requires only estimates of star mass planet massand orbital period making it possible to immediately classify 99of all known exoplanets All 8 planets and all classifiable exoplanetssatisfy the criterionI will describe the development of the metric and apply it to solarsystem bodies exoplanets and pulsar planets I will then show howthis metric could be used to quantify generalize and simplify thedefinition of planet A preprint is available at httparxivorgabs150706300

Author(s) Jean-Luc MargotInstitution(s) 1 University of California Los Angeles

50104D ndash Dynamical Heating Induced by DwarfPlanets on Cold Kuiper Belt-like Debris DisksWith the use of long-term numerical simulations we study theevolution and orbital behavior of cometary nuclei on cold Kuiperbelt-like debris disks under the gravitational in uence of dwarfplanets (DPs) we carry out these simulations with and without thepresence of a Neptune-like giant planet This comprehensive studyshows that in the absence of a giant planet 10 DPs are enough toinduce strong radial and vertical heating on the orbits of beltparticles On the other hand the presence of a giant planet close tothe debris disk acts as a stability agent reducing the radial andvertical heating With enough DPs even in the presence of aNeptune-like giant planet some radial heating remains thisheating grows steadily re-lling resonances otherwise empty ofcometary nuclei This seems to work as a plausible secular processable to provide material that after falling into the resonances withthe giant through resonant chaotic diusion could sustain a rate ofnew comets spiraling into the inner planetary system

Author(s) Marco Antonio Muntildeoz-Gutieacuterrez BarbaraPichardo Mauricio Reyes-Ruiz Antonio PeimbertInstitution(s) 1 Instituto de Astronomiacutea UNAM

50105 ndash Masses of the Five Small Planets AroundKepler-80Kepler has discovered hundreds of multi-transiting systems whichhold tremendous potential both individually and collectively forunderstanding the formation and evolution of planetary systemsMany of these systems are quite compact containing 3-7 relativelysmall planets with periods less than 100 days these are known asSystems with Tightly-packed Inner planets or STIPs One ultra-compact STIP is KOI-500Kepler-80 a planetary systemcontaining five transiting planets ranging in size from 15 to 28times the radius of the Earth that orbit in a tightly-packedconfiguration with periods between 1 and 10 days In addition to itsclose packedness the outer four planets are in a unique dynamicalconfiguration with two interconnected three-body resonancesUsing transit timing variations (TTVs) caused by the gravitationalperturbations we perform a fully self-consistent dynamicalanalysis of the system finding best-fit masses for the outer fourplanets to be each around five Earth masses We also performedextensive testing of synthetic systems and have determined thateccentricities cannot be reliably detected but that assumingcircular orbits does not significantly affect the mass estimates Wewill present the inferred properties for Kepler-80 and discuss theseresults in context of (ultra-compact) STIPs and the small planetmass-radius relation

Author(s) Mariah G MacDonald Darin Ragozzine DanielC FabryckyInstitution(s) 1 Florida Institude of Technology 2 Universityof Chicago

50106 ndash The search for ExomoonsThere are hundreds of Exoplanets which the data are available fordynamical investigation There is a wealth of diversity of

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Exoplanets types and the expectation in finding our Earth-livingconditions in another planet motivates the search for Extra-solarplanets A satellite around a planet in the habitable zone would inaddition contributes to keep the climate The main objective of thiswork is to provide a list of the best planet candidates to harbor adetectable exomoon by the current telescopes such as the Keplermission so as to guide the searches The planets were sorted outinto class groups according to their masses and radii For eachplanet we have calculated the stability region where an exomooncan exist for a long period of time The outer boundary isdetermined from the critical stability limit obtained from dynamicalnumerical simulation of a restrict three body problem whereas theinner boundary is given by the Roche limit Moreover the satellitehas to be bigger than a certain value to be detected in the noisytransit lightcurves of the CoRoT and Kepler missions Wedetermined the maximum radius of the stability zone for severalplanet types and proved that the relation reported in a previouswork by Domingos et al (2006) only for hot Jupiters is valid for allplanet class Considering moons of different densities (iceice-rock rock rock-iron iron) able to survive within the calculatedstability region and with a minimum detectable size we derived alist of the best 38 planet candidates with orbiting moons A list ofthe top ten planet candidates where exomoons should be searchedwithin the Kepler transit lightcurves is given These planets couldharbor big enough moons to be detected above the data noise forany moon composition

Author(s) Ana Helena Fernandes Guimaratildees AdrianaBenetti Marques Valio Luis Ricardo Moretto Tusnski ErnestoVieira-NetoInstitution(s) 1 INPE - Instituto Nacional de PesquisasEspaciais 2 Mackenzie Presbyterian University 3 UNESP -University of State of Satildeo Paulo

50107 ndash The Primordial Destruction of Moons aroundGiant Exoplanets through Disk-Driven PlanetaryMigrationThe extensive array of satellites around Jupiter and Saturn makes itreasonable to suspect that similar systems of moons might existaround giant extrasolar planets Observational surveys haverevealed a significant population of such giant planets residing atdistances of about 1 AU leading to speculation that some of theseexomoons might be capable of maintaining liquid water on theirsurfaces Accordingly many recent efforts have specifically huntedfor moons around giant exoplanets Owing to the lack of detectionsthus far it is worth asking whether certain processes intrinsic toplanet formation might lead to the loss of moons Here wehighlight that giant planets are thought to undergo inwardmigration within their natal disks and show that the very process ofmigration naturally captures moons into a so-called evectionresonance Within this resonance the lunar orbits eccentricitygrows until the moon is lost either by collision with the planet orthrough tidal disruption Whether moons survive or not is criticallydependent upon where the planet began its inward trek In thisway the presence or absence of exomoons can inform us on theextent of inward migration for which no reliable observationalproxy currently exists

Author(s) Christopher Spalding Konstantin Batygin FredC AdamsInstitution(s) 1 California Institute of Technology 2University of Michigan

50108 ndash Tidal Decay and Disruption of GaseousExoplanetsMany gaseous exoplanets in short-period orbits are on the verge ofRoche-lobe overflow and observations along with orbital stabilityanalysis show tides probably drive significant orbital decay Thusthe coupled processes of orbital evolution and tidal disruptionlikely shape the observed distribution of close-in exoplanets andmay even be responsible for producing the shortest-period solidplanets However the exact outcome for an overflowing planetdepends on its internal response to mass loss and variable stellarinsolation and the accompanying orbital evolution can act to

enhance or inhibit the disruption process The final orbits of thedenuded remnants of gas giants may be predictable from theirmass-radius relationship and so a distinctive mass-periodrelationship for some short-period solid planets may provideevidence for their origins as gaseous planets In this presentationwe will discuss our work on tidal decay and disruption of close-ingaseous planets using a new model that accounts for the fact thatshort-period planets have hot distended atmospheres which canresult in overflow even for planets that are not officially in Rochelobe contact We will also point out that the orbital expansion thatcan accompany mass transfer may be less effective than previouslyrealized because the resulting accretion disk may not return all ofits angular momentum to the donor as is usually assumed Both ofthese effects have bee incorporated into the fully-featured androbust Modules for Experiments in Stellar Astrophysics (MESA)suite

Author(s) Brian K Jackson Phil Arras Emily Jensen Sarah Peacock Pablo Marchant Kaloyan PenevInstitution(s) 1 Boise State University 2 Princeton University3 Universitaumlt Bonn 4 University of Arizona 5 University ofVirginia

502 ndash Jovian Planet MagnetospheresAurorae and Atmospheres50201 ndash Transport of magnetic flux in Saturnrsquos innermagnetosphereThe dynamics of the Saturnian magnetosphere which rotatesrapidly with an internal plasma source provided by Enceladusqualitatively resembles those of the jovian magnetosphere poweredby Io The newly added plasma is accelerated to the corotationspeed and moves outward together with the magnetic flux In thenear tail region reconnection cuts the magnetic flux reconnects itinto plasma-depleted inward moving flux tubes and outwardmoving massive plasmoids The buoyant empty tubes then convectinward against the outward flow to conserve the total magnetic fluxestablished by the internal dynamo In both jovian and saturnianmagnetospheres flux tubes with enhanced field strength relative totheir surroundings are detected in the equatorial region Recentobservations show that there are flux tubes with reduced fieldstrength off the equator in the saturnian magnetosphere Tounderstand the formation mechanism of both types of flux tubeswe have surveyed all the available 1-sec magnetic field data fromCassini The systematic statistical study confirms the differentlatitudinal distributions of the two types of flux tubes In additionenhanced-field flux tubes are closer to the planet whilereduced-field flux tubes can be detected at larger distances bothtypes of flux tubes become indistinguishable from the backgroundmagnetic flux inside an L-value of about 4 the local timedistribution of both types of flux tubes are similar and they containabout the same amount of magnetic flux Therefore the two typesof flux tubes are the same phenomena with differentmanifestations in different plasma environments When thesurrounding plasma density is high (near the equator and closer tothe plasma source region) the flux tubes are compressed and haveenhanced field strength inside while in the low-plasma densityregion (off the equator and further from the plasma source region)the flux tubes expand and have reduced field strength inside

Author(s) Christopher T Russell H R Lai H Y Wei YD Jia M K DoughertyInstitution(s) 1 Imperial College London 2 UC Los Angeles

50202 ndash Ground-based and Space-based Observationsof Jovian Mid-Infrared Aurora During the CassiniFlyby of Jupiter 2000ndash2001We report on a re-examination and re-analysis of hydrocarbonemission spectra collected from Jupiter using ground-basedultra-high spectral resolution infrared heterodyne spectroscopy(IRHS) and space-based Fourier transform spectroscopy (FTS)from the Cassini spaceraft during its flyby of Jupiter in 2000-2001Auroral emission by ethane was measured from Earth with the

22 1

3

1 12

1 5 14 3 2

2 2 22 1

160

Heterodyne Instrument for Planetary Wind and CompositionHIPWAC in December 2000 and in February 2001 Shapes ofindividual emission lines of ethane near 12 microm wavelength weremeasured from the polar regions of Jupiter at spectral resolvingpower of 1000000 These observations were conducted in concertwith scheduled observations of the Jovian auroral region by theCassini Composite Infrared Spectrometer (CIRS) at resolvingpowers of ~2000 before and after closest approach on December30 2000 The HIPWAC measurements complement CIRS broadspectral and spatial coverage with its uniquely high spectralresolution and spatial discrimination from the ground comparableto that at Cassinirsquos closest approach Fully resolved ethane linemeasurements retrieve both temperature and ethane abundanceinformation at the north and south auroral hot spots CIRS data atcoarser spectral resolution provide extended spatial distributionscovering a broad spectral band including abundances and auroralresponse of several hydrocarbon constituents in the 8ndash13micrometer spectral region (ethane methane ethylene andacetylene) Preliminary studies of both data sets reveal temporalvariability and low enhancement of the thermal infrared auroraeduring the flyby compared to other periods observed Analyses ofboth data sets will be reported and retrievals will be comparedResults will be useful to interpreting the Juno mission since thiswork provides complementary information and diagnostics tostudy Jupiter in a spectral region and altitude range not directlyprobed by Juno

Author(s) Theodor Kostiuk Tilak Hewagama Timothy ALivengood Kelly E Fast Gordon L Bjoraker Ronald Carlson Frank Schmuumllling Conor A NixonInstitution(s) 1 Catholic University of America 2 DLR 3NASA HQ 4 NASAs GSFC 5 University of Maryland

50203 ndash Jupiter Climatological Database fromFrequent 5-25 microm Mid-IR Spectral Mapping usingIRTFTEXESWe report on the development of a long-term Jovian ClimatologicalDatabase (JCliD) to explore variability in Jupiterrsquos atmospherictemperatures winds clouds and compositionndash from long-termseasonal changes to short-term major upheavals Radiometricallycalibrated spectral scan maps of Jupiter have been regularlyobtained using the TEXES instrument (Texas Echelon crossEchelle Spectrograph Lacy et al 2002 PASP 114 p153-168)between 2012 and 2015 Ten settings between 5 and 25 microm (10-20cm wide settings at spectral resolutions of 2000-10000) wereselected to be sensitive to jovian temperatures (via H CH andCH D) tropospheric phosphine and ammonia tropospheric hazeopacity and stratospheric hydrocarbons ethane and acetyleneDiffraction-limited spatial resolutions of 06-16rdquo were achievedObservations over consecutive nights allow the creation of fullspatial maps for comparison with the visible light record revealingephemeral stratospheric wave activity NEB hotspots heating atthe northern auroral oval and complex thermal signaturesassociated with tropospheric vortices waves and barges Fullspectra are inverted via the NEMESIS retrieval algorithm (Irwin etal 2008 JSQRT 109 p1136-1150) to map temperatures at multiplealtitudes (1-600 mbar) winds aerosol opacity and gaseouscomposition The spatial and spectral resolutions of the resultingmaps surpass those obtained during the Cassini flyby of Jupiter in2000 and permit temporal interpolation to understand theenvironmental conditions related to the emergence and evolutionof discrete features In December 2014 we find warmertemperatures in the northern stratosphere (a seasonal effect in latenorthern summer despite Jupiterrsquos small axial tilt) a hemisphericasymmetry in the tropospheric PH distribution due to variationsin the vigour of vertical mixing and photolytic shielding elevatedPH aerosols and NH in the equatorial zone (EZ) related toequatorial uplift elevated aerosol opacity in the northern andsouthern tropical zones (NTrZ and STrZ) and enhanced PH andaerosols over the Great Red Spot Maps of retrieved properties willbe assembled as a database (JCliD) to aid in the interpretation ofJuno data during 2016-2017

Author(s) Leigh N Fletcher Glenn S Orton Thomas KGreathouse James Sinclair Patrick GJ Irwin Rohini SGiles Therese Encrenaz Pierre DrossartInstitution(s) 1 LESIA Observatoire de Paris 2 NASA JetPropulsion Laboratory 3 Southwest Research Institute 4University of Leicester 5 University of Oxford

50204 ndash Are Brown Barges the Deserts of the UpperJovian AtmosphereSince the descent of the Galileo probe into one of Jupiterrsquos 5-micromhot spots these regions have been characterized as the driest andclearest regions on the planet We are presenting evidence that thisgeneralization could be premature at least for Jupiterrsquos uppertroposphere Diffraction-limited mid-infrared images of Jupitertaken from the Subaru Telescope using the COMICS instrumentthe Very Large Telescope (UT3) using the VISIR instrument andthe Gemini South Telescope using the T-ReCS instrument resolveregions with the highest brightness anywhere on the planet atwavelengths near 98-105 microm a region sensitive to the abundanceof ammonia gas above its condensation level These brightnessesare so high that they require ammonia abundances that are manytimes lower than anywhere else on the planet A similar drop of theoptical thicknesses of clouds near the ammonia-gas condensationlevel is required diagnosed using 87-89-microm radiances Thesefeatures are also detected but not spatially resolved in observationsobtained at NASArsquos Infrared Telescope Facility using the MIRSIimager and the TEXES scanning spectrometer Most are locatedalong the northern edge of the North Equatorial Belt and areassociated with cyclonic features known as ldquobrown bargesrdquo Theyare not associated with detectable changes in upper-tropospherictemperatures requiring convective activity to take place at depthswith very rapid dynamical readjustment Regions bright at 8-10 micromare not always bright in the deep 5-microm window implying that somebrown barges are clear of condensate gases and clouds only downto 06 bars but others are clear down to 2-3 bars a possibleconsequence of observing them in different phases of their ldquolifecyclerdquo These other discrete features and broader regions will bethe objects of intensive investigations by the Juno mission andassociated Earth-based observational support in 2016 to 2018

Author(s) Glenn S Orton James Sinclair Leigh Fletcher Takuya Fujiyoshi Padma Yanamandra-Fisher John Rogers Patrick Irwin Thomas Greathouse Raiyan Seede JasonSimon Marian Nguyen Matthew LaiInstitution(s) 1 British Astronomical Association 2 CaliforniaInstitute of Technology 3 California State University 4 JPL 5Southewest Research Institute 6 Space Science Institute 7 SubaruTelescope 8 University of Leicster 9 University of Oxford 10University of Paris Sorbonne Abu Dhabi

50205 ndash First results from the Hubble OPALProgram Jupiter in 2015The Hubble 2020 Outer Planet Atmospheres Legacy (OPAL)program is a Directors Discretionary program designed to generatetwo yearly global maps for each of the outer planets to enable longterm studies of atmospheric color structure and two-dimensionalwind fields This presentation focuses on Jupiter results from thefirst year of the campaign Data were acqured January 19 2015 withthe WFC3UVIS camera and the F275W F343N F395N F467MF502N F547M F631N F658N and F889N filters Global mapswere generated and are publicly available through the High LevelScience Products archive httpsarchivestscieduprepdsopalUsing cross-correlation on the global maps the zonal wind profilewas measured between +- 50 degrees latitude and is in family withVoyager and Cassini era profiles There are some variations in midto high latitude wind jet magnitudes particularly at +40degand -35degplanetographic latitude The Great Red Spot continues to maintainan intense orange coloration as it did in 2014 However theinterior shows changed structure including a reduced core andnew filamentary features Finally a wave not previously seen inHubble images was also observed and is interpreted as a baroclinicinstability with associated cyclone formation near 16deg N latitude Asimilar feature was observed faintly in Voyager 2 images and isconsistent with the Hubble feature in location and scale

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3

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5 1 1

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161

Author(s) Amy A Simon Michael H Wong Glenn SOrtonInstitution(s) 1 Jet Propulsion LaboratoryCaltech 2 NASAsGSFC 3 University of California at Berkeley

50206 ndash Ammonium Hydrosulfide Coloring JupitersCloudsThe appearance and composition of Jupiterrsquos Great Red Spot (GRS)have been studied for over a century yet there still is no consensusfor what is causing the GRSrsquos color As the GRS is believed tooriginate in tropospheric clouds it seems likely that one or morecloud components may contribute to the GRSs color Recently wehave begun to investigate whether either ammonium hydrosulfide(NH SH) a predicted cloud component or its radiation-chemicalproducts can produce color andor an ultraviolet-visible spectrumsimilar to what has been observed on Jupiter via remote sensing(eg Simon et al 2015) Our initial experiments relied on infraredspectroscopy to quantify the radiolytic and thermal stability ofNH SH and to identify the new chemical products formed duringMeV ion irradiation (Loeffler et al 2015) This DPS presentationwill cover some of our most recent results detailing the ultraviolet-visible spectral and color changes observed during irradiation andpost-irradiation warming of NH SH ices This work is funded byNASArsquos Outer Planets and Planetary Atmospheres programs

Author(s) Mark J Loeffler Reggie L Hudson Nancy JChanover Amy A SimonInstitution(s) 1 NASA GSFC 2 New Mexico State University

50207 ndash Deriving Saturns Zonal Winds from CassiniRadio OccultationsTracking cloud features from visible images have provided detailedmaps of the meridional variation of the mean zonal winds on thegiant planets including Saturn Filters at different wavelengths canprovide information on the vertical structure of the zonal windsbut that is approximate and the altitudes of winds observed with agiven filter generally vary with location because cloud heights doRadio occultations provide vertical profiles of refractivity pressureand temperature vs altitude Zonal winds can be derived from theassumption of gradient wind balance which relates the zonal windto the change of geopotential height with latitude along an isobarOccultations have the advantage that vertical profiles of winds canbe obtained in the troposphere and stratosphere There arehowever complicating factors In general the meridionaldistribution of occultation soundings is limited and unevenlydistributed Moreover one needs to know the geometry of theocculting atmosphere to correctly account for the path of therefracted radio signal The zonal winds matter because they distortisobaric surfaces For example an inversion that includes Saturnsoblateness from uniform rotation based on the Voyager System IIIperiod would yield equatorial temperature profiles that are shiftedby ~ 2 K relative to one that also includes the differential rotationassociated with the cloud-tracked zonal winds In retrieving verticalprofiles of atmospheric variables from occultation soundings onealso needs an additional symmetry assumption to make theinversions tractable Typically one uses the zonal winds based oncloud-tracking studies and assumes they are axisymmetric andbarotropic so that both the gravitational and centrifugal forces arederivable from a potential and the surfaces of constantgeopotential height pressure and temperature coincide Thisforms the basis for an iterative approach The pressures andtemperatures so retrieved from the occultation soundings are notbarotropic but the zonal winds derived from the gradient windequation can be added to the cloud-tracked winds used in theinversions We discuss Saturns equatorial soundings as anillustration

Author(s) F Michael Flasar Paul J SchinderInstitution(s) 1 Cornell University 2 NASAs GSFC

50208 ndash A Ring-lsquoRainrsquo influence for Saturnrsquos CloudAlbedo and Temperatures Evidence Pro or Con fromVoyager HST and CassiniJ E P Connerney [Geophys Res Lett 13 773-776 1986] pointed

out that lsquolatitudinal variations in images of Saturnrsquos disk upperatmospheric temperatures and ionospheric electron densities arefound in magnetic conjugacy with features in Saturnrsquos ring planersquoand proposed lsquothat these latitudinal variations are the result of avariable influx of water transported along magnetic field lines fromsources in Saturnrsquos ring planersquo Observations of H support aring-ionosphere connection [ODonoghue et al Nature 496 74442013] What about cloud albedo and temperature Connerneyattributed a hemispheric asymmetry in haze and temperature to anasymmetry in water flux and predicted that lsquothe presently-observednorth-south asymmetry (upper tropospheric temperaturesaerosols) will persist throughout the Saturn yearrsquo We can now testthese ideas with data from the Cassini mission from the HubbleSpace Telescope and from ground-based observations Analyses ofground-based images and especially Hubble data established thatthe hemispheric asymmetry of the aerosol population does changeand seasonal effects are dominant although non-seasonalvariations are also observed [Karkoschka and Tomasko Icarus 179195-221 2005] Upper tropospheric temperatures also vary asexpected in response to seasonal forcing [Fletcher et al Icarus208 337-352 2009] Connerney also identified dark bands inVoyager Green-filter images on magnetic conjugacy with the E ringand edges of the A and B rings In Cassini Green-filter images thereis some correspondence between dark bands and ring features inmagnetic conjugacy but collectively the correlation is not strongCassini 727-nm methane band images do not suggest depletion ofaerosols in the upper troposphere at ring edge magnetic conjugacylatitudes as proposed by Connerney We conclude that ring raindoes not have a significant influence on upper troposphericaerosols and temperatures on Saturn Part of this work wasperformed by the Jet Propulsion Lab Calif Institute ofTechnology

Author(s) Robert A West Liming LiInstitution(s) 1 JPL 2 Univ of Houston

50209D ndash Determining the vertical extent of JupitersGreat Red Spot with the Juno gravity measurementsThe NASA Juno mission is due to arrive at Jupiter in July 2016 Weexplore the possibility of inferring the depth of Jupiterrsquos biggestvortex the Great Red Spot (GRS) by determining its gravitationalsignature with the onboard gravity experiment consideringdifferent possible scale heights for the vortex We estimate thestrength of the gravity signal coming from the vortex using anidealized dynamical model for the atmosphere of the giant planetThe gravity anomaly is then compared to the expected accuracy inthe retrieval of the surface gravity at the GRS location obtainedwith numerical simulations of the Doppler data inversion based onthe expected trajectory of the spacecraft Starting from observationsof the planets velocity vectors at the cloud level we propagate theprofiles along coaxial cylinders parallel to the spin axis and explorea wide range of decay scale heights in the radial directionAssuming the large scale vortex dynamics are geostrophic andtherefore thermal wind balance holds the density anomalydistribution due to Jupiters winds can be derived from the velocitymaps The novelty of this approach is in the integration of thermalwind relations over a three-dimensional grid and in the inclusionof the observed meridional velocity as measured during the Cassiniflyby of Jupiter The introduction of longitudinal perturbations tothe mean zonal flows gives rise to fluctuations in the tesseralspherical harmonics of Jupiters gravitational potential We showthat the deeper the penetration of the jets the stronger is thegravity signal coming from the GRS On the other hand the largerthe mass involved in the planets atmospheric motion the higherare the degree and order of the spherical harmonic expansion ofJupiters gravity field needed to fit the simulated Doppler data Weshow that the mass anomaly associated with the Great Red Spot isdetectable by the Juno gravity experiment if the winds penetrate atdepth of 2000 km below the cloud level of Jupiter and that thelarge mass involved with deep winds does not render much theability to measure the feature

2 31

4

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3+

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162

Author(s) Marzia Parisi Eli Galanti Stefano Finocchiaro Luciano Iess Yohai KaspiInstitution(s) 1 Sapienza Universitagrave di Roma 2 WeizmannInstitute of Science

503 ndash Comet 67PC-G -- Coma andEnvironment50301 ndash One year at the comet highlights from theROSINA instruments on the composition andevolution of the cometary comaAfter one year in the close vicinity of comet 67PChuryumov-Gerasimenko we report on the most surprising results from theRosetta Orbiter Sensor for Ion and Neutral Analysis (ROSINA) onRosetta which is analysing the volatile composition of the cometarycoma since more than 15 months Several species like N and Arwere detected for the first time in a cometary coma others havebeen detected before in long period but not in Jupiter familycomets There are significant amounts of long carbon chainmolecules Many of them are probably related to dust We will givean overview on the inventory of volatile and less volatile speciesThe coma is quite heterogeneous and the relative abundances varyby factors between summer and winter hemisphere The evolutionof the abundances with heliocentric distances and solarillumination will be discussed

Author(s) Kathrin Altwegg Hans Balsiger UrsinaCalmonte Seacutebastien Gasc Myrtha Haumlssig Leacutena LeRoy Annette Jaumlckel Martin Rubin Peter Wurz Chia-Yu Tzou Urs Mall Bjoumlrn Fiethe Johan de Keyser Jean-JacquesBerthelier Henri Regraveme Tamas Gombosi Steven FuselierInstitution(s) 1 BIRA 2 Center for Space and Habitability 3IRAP 4 LATMOS 5 Max-Planck Insitut fuumlr Sonnenphysik 6SwRI 7 Technische Universitaumlt Braunschweig 8 University ofBern 9 University of Michigan

50302 ndash Comet 67P Nucleus-Coma Interaction andComa Structure Observed with RosettaMIROThe Microwave Instrument on the Rosetta Orbiter (MIRO)operating at frequencies near 190 GHz and 562 GHz has beenobserving Comet 67P nucleus thermal emissions and comamolecular lines since May 2014 As Comet 67P approachesperihelion in its orbit around the Sun MIRO witnesses that thenucleus heats up and emits more volatiles creating a densecomplex and rich coma structure In order to study nucleus-comainteractions and coma structure and evolution MIRO has usedspecially designed scan patterns called ldquoInner Coma Maprdquo andldquoNucleus Gas Emissionrdquo which cover the nucleus limb and innercoma region in detail In this paper we will present the MIROmolecular line measurements with those scan patterns fromJanuary 2015 to August 2015 We have analyzed the linemeasurements with a non local-thermal-equilibrium molecularradiative transfer model and an optimal estimation method in orderto retrieve nucleus and coma parameters such as outgassing ratecolumn density expansion velocity and gas kinetic temperatureAlong with the line analysis retrieval results we will discuss theimplication of the results on nucleus-coma interactions comastructure and their temporal evolutions

Author(s) Seungwon Lee Paul von Allmen Samuel Gulkis Mathieu Choukroun Mark Hofstadter Margaret A Frerking Crovisier Jacques Gerhard BeaudinInstitution(s) 1 Jet Propulsion Laboratory 2 LERMAObservatoire de Paris 3 LESIA-Observatoire de Paris

50303 ndash Observed changes in the physicalenvironment and chemistry in the inner coma of67PChuryumov-GerasimenkoThe Optical Spectroscopic and Infrared Remote Imaging System(OSIRIS) on board Rosetta consists of two bore-sighted cameras(Keller et al 2007) Its Wide Angle Camera includes narrow-bandfilters to image gaseous emission by CS OH NH CN NH Na

and [O I]OSIRIS monitored gas about once every two weeks for heliocentricdistances greater than 2 AU and weekly afterward Images werecalibrated using the OSIRIS pipeline (Tubiana et al 2015) andfurther processed to remove the continuum flux and the emissionfrom other molecules with lines that fall within the narrowbandfiltersrsquo passbandsMany collimated jets are visible in the continuum images (Lara etal 2015 Lin et al 2015) Those jets are not present in the gasimages The morphology of the gas images is either focused in aprojected cone (OI CN) or diffuse and roughly isotropic (OH NHCS NH ) We interpret the first as the signature of promptemission (where fragmentation of a molecule released from thenucleus directly produces a radical in an excited state) and thesecond as that of excitation of fragments species after they wereformedSurprisingly up to the spring of 2015 all measured surfacebrightnesses are more than 10x higher than can be accounted forby formation and excitation processes as understood from remotesensing of comets This changed in the summer of 2015 andcurrent measurements are consistent with photodissociation andfluorescence rates This change reflects the transition of 67P from adistant comet with extremely low gas production rates to conditionsunder which comets are normally observed

Author(s) Dennis Bodewits Luisa M Lara FiorangelaLaForgia Michael F AHearn Joerg Knollenberg MonicaLazzarin Zhing-Yi Lin Xian ShiInstitution(s) 1 Deutsches Zentrum fuumlr Luft- und Raumfahrt 2Institute for Space Science National Central University 3Instituto de Astrofisica de Andalucia-CSIC 4 Max-Planck Institutfuumlr Sonnensystemforschung 5 University of Maryland 6University of Padova

50304 ndash Water and carbon dioxide investigation inthe inner coma of 67PChuryumov-GerasimenkoThe study of 67PCG coma environment is one of the primaryscientific goals of the VIRTIS experiment aboard ESA RosettamissionIn the present work results of 74 observations acquired byVIRTIS-M IR channel in the 1-5 μm spectral range from 8 to 14April 2015 are discussed In this time 67PCG was at heliocentricdistance of 19 AU and the coma activity was monitored for about10 full comet rotations This allows one to tentatively correlate gasdistribution with active areas on the nucleus and to disentangle gasemissions from dustVibrational emission lines of H O and CO at 267 and 427 μmrespectively are identified by VIRTIS-M imaging channel andmapped from the surface up to about 10 km altitude with a spatialresolution of approximately 40 mpxThe maximum H O emission is mainly concentrated aboveAten-Babi and Seth-Hapi active regions which are located on theneck connecting the two principal lobes The CO column densityis quite poor in the neck region while diffuse emission is clearabove the small and great lobe regions These observations confirmthe anti correlation between these two main species as alreadynoticed by Bockeleacutee-Morvan et al (2015) and Haumlssig et al (2014)Column density of both species decreases with altitude with theCO2 distribution decreasing more rapidly than the H2O TheH OCO ratio which increases with the altitude varies from 187close to the nucleus to 308 at 2-3 km above the nucleus Thesevalues refer to the equatorial region calculated considering all thelongitudes Gas emission is maximum in the afternoon quadrantfrom 12 LST to 18 LSTVIRTIS-M has revealed with unprecedented spatial resolution thedistribution of gaseous species around a cometary nucleus andcorrelated the emissions with surface-active areas altitude abovethe nucleus and local time Our study confirms the asymmetricdistribution of carbon dioxide which has a more uniformdistribution above the comets nucleus than water vapour (Haumlssiget al 2014 Bockeleacutee-Morvan et al 2015 Capaccioni et al 2015)and improves our knowledge about the spatial and temporaldistribution of the gases in the lower coma

2 2 11 2

2

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4 3 9 6

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3 2

2

2

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2 2

2

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163

Author(s) Alessandra Migliorini Giuseppe Piccioni Fabrizio Capaccioni Gianrico Filacchione Dominique Bockeleacutee-Morvan Stefan Erard Cedric Leyrat Michael Combi NicolasFougere Maria Cristina De SanctisInstitution(s) 1 IAPS-INAF 2 LESIA - Observatoire de Paris 3Space Physics Research Laboratory University of Michigan

50305 ndash Rosetta-Alice Observations of the Evolutionof the CO Coma of Comet 67PChuryumov-Gerasimenko During PerihelionAlice is a lightweight low-power far-ultraviolet (700 ndash 2050 Aring)spectrograph onboard Rosetta designed for in situ imagingspectroscopy of the cometary coma during the rendezvous withcomet 67PChuryumov-Gerasimenko We initially reported onspectra obtained following orbit insertion in August 2014 thatshowed multiplets of atomic hydrogen oxygen and carbonconcentrated above the limb of the comet From the relativeintensities of these multiplets we identified photoelectron impactdissociative excitation of H O and CO as the source of theobserved atomic emissions Variations in the relative intensitieswere interpreted in terms of variations in the molecularabundances Emission from CO via resonance fluorescence in theFourth Positive Band system was observed only sporadicallyBeginning in July 2015 as the comet approached perihelion on 13August 2015 the CO emission bands became a strong persistentfeature of the observed spectrum in addition to the atomicmultiplets The CO emissions exhibit a very strong sunwardanti-sunward asymmetry as well as a brightness variation withrotational phase of the comet CO column densities are derivedusing the fluorescence model of Lupu et al (ApJ 670 1473 2007)and compared with the predictions of DSMC models and withconcurrent measurements of H O and CO column densities Thelong term evolution of the CO coma through the cometrsquos perihelionpassage will be presented

Author(s) Paul D Feldman Michael F AHearn Jean-Loup Bertaux Lori M Feaga Joel Wm Parker EricSchindhelm Andrew J Steffl S Alan Stern Harold A WeaverInstitution(s) 1 Johns Hopkins Univ 2 Johns Hopkins UnivApplied Physics Laboratory 3 LATMOS 4 Southwest ResearchInstitute 5 University of Maryland

50306 ndash Comet 67PChuryumov-GerasimenkorsquosIncreasing Atomic Sulfur Abundance Observed byRosetta AliceAlice NASArsquos lightweight and low-power far-ultraviolet (FUV)imaging spectrograph onboard ESArsquos comet orbiting spacecraftRosetta (Stern et al 2007) is continuing its characterization of thenucleus and coma of the Jupiter family comet 67PChuryumov-Gerasimenko (C-G) as it approaches and recedes from perihelionWith a spectral range from 700-2050 Aring Alice has the ability todetect the atomic sulfur multiplets at 1429 Aring 1479 Aring and 1814 AringSulfur in C-Grsquos coma is most likely a dissociation product of CSand OCS but could also be produced after a secondary dissociationfrom H S and SO all molecular species measured in C-Grsquos comaby ROSINA the Rosetta orbiterrsquos mass spectrometerDue to low abundances Alice did not detect sulfur atoms at C-Guntil May 2015 when the comet was at ~17 AU and still 3 monthsfrom perihelion Now sulfur is ubiquitous in Alice observationsabove the limb of the nucleus There is evidence that there is not astrong dependence of the abundance of sulfur on the distance fromthe nucleus in the pre-perihelion radial profiles of the gas whichmay be indicative of the parent molecule and its distribution Thiswill be investigated further The evolution of the presence of thethree sulfur multiplets their relative abundances and excitationprocesses and behavior pre- and post-perihelion will be presented

Author(s) Lori M Feaga Paul D Feldman Michael FAHearn Jean-Loup Bertaux Brian A Keeney Matthew MKnight John Noonan Joel Wm Parker Eric Schindhelm Andrew J Steffl S Alan Stern Ronald J Vervack Harold AWeaverInstitution(s) 1 Johns Hopkins University 2 Johns HopkinsUniversity Applied Physics Lab 3 LATMOS CNRSUVSQIPSL4 Lowell Observatory 5 Southwest Research Institute 6 Univ ofMaryland 7 University of Colorado

50307 ndash Study of the characteristics of the grains inthe coma background and in the jets in comet67PC-G as observed by VIRTIS-M onboard of theRosetta missionWe report observations of the coma of the comet 67PC-Gperformed in the near-IR by VIRTIS-M during the escort phase inApril 2015 We selected observations performed when thespacecraft was at about 150 km from the nucleus in order to coverthe greatest part of the comaWe have chosen observations a) with a diffuse coma without anyevident strong jets and b) with strong jets originating from theldquoneckrdquo region of the nucleusWe analyzed the in changes intensity and spectral behavior of thecoma along the projected nucleocentric distance for both thediffuse coma and for the jetsThe results show that- The emission of the grains in the diffuse coma is going as 1rho inthe FoV of VIRTIS (about 2 km) suggesting the absence of grainfragmentation or sublimation In the region close to the surfacewithin about 400 m there is an increase of the emission which isprobably due to instrumental scattered light from the nucleus thatcan hide the effects due to the grains acceleration- Also for the grains in the jets there is no evidence offragmentation or sublimation in the spectral region where thescattering of the solar radiation is the mechanism of emissionInstead in the thermal region there are strong variations betweenthe regions close to the nucleus and the farther onesThe authors would like to thank ASI (I) CNES (F) DLR (D) NASA(USA) for supporting this research VIRTIS was built by aconsortium formed by Italy France and Germany under thescientific responsibility of the ldquoIstituto di Astrofisica e PlanetologiaSpazialerdquo of INAF (I) which guides also the scientific operationsThe consortium includes also the ldquoLaboratoire deacutetudes spatiales etdinstrumentation en Astrophysiquerdquo of the Observatoire de Paris(F) and the ldquoInstitut fuumlr Planetenforschungrdquo of DLR (D) Theauthors wish to thank the Rosetta Science Ground Segment andthe Rosetta Mission Operations Centre of ESA for their continuoussupport

Author(s) Gian-Paolo Tozzi G Rinaldi U Fink LDoose F Capaccioni G Filacchione D Bockeleacutee-Morvan SErard C Leyrat G Arnold M Blecka M T Capria MCiarniello M Combi S Faggi P Irwin A Migliorini EPaolomba G Piccioni F TosiInstitution(s) 1 Departement of Physics Oxford University 2DLR 3 INAF 4 LESIA-Observatoire de Paris 5 LPL 6 SpaceResearch Centre PAS 7 SPRL The University of Michigan

50308 ndash COSIMA - In-situ dust particlesmeasurements in the inner coma of comet67PChuryumov-GerasimenkoCOSIMA the COmetary Secondary Ion Mass Analyzer is one ofthe three in-situ dust instruments onboard the Rosetta spacecraft[1] Since August 2014 Rosetta has been escorting the comet67PChuryumov-Gerasimenko on its journey toward the innersolar systemCOSIMA is collecting cometary dust particles by exposing metaltargets in the inner coma from 10 to hundreds of kilometers off thecometary nucleus [2] Already several thousands of dust particleshave been collected The targets are imaged with the microscopeCOSISCOPE and some collected particles are then analyzed bySIMS (Secondary Ion Mass Spectrometry) The mass spectracontain positive and negative ions revealing components of thegrains originating from selected surface areas Dust characteristics

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4 4 2 6 33 7 3 1 33 3 3

164

will be presented and discussed[1] Kissel et al (2007) Sp Sci Rev 128 82-867 [2] Schulz et al(2015) Nature 518 216-218

Author(s) Anais Bardyn Martin Hilchenbach ChristelleBriois Jochen Kissel Andreas Koch Yves Langevin RitaSchulz Johan Silen Kathrin Altwegg Luigi Colangeli HerveCottin Cecile Engrand Henning Fischer AlbrechtGlasmachers Eberhard Gruumln Gerhard Haerendel HartmutHenkel Herwig Houmlfner Klaus Hornung Elmar KJessberger Harry Lehto Kirsi Lehto Francois Raulin Lena Le Roy Jouni Rynouml Wolfgang Steiger ThomasStephan Laurent Thirkell Roger Thomas Klaus Torkar Kurt Varmuza Karl-Peter Wanczek Nicolas Altobelli DoniaBaklouti Nicolas Fray Pedro Lacerda Nicolas Ligier ZhongYi Lin Philippe Martin Sihane Merouane Franccedilois-Reacutegis Orthous-Daunay John Paquette ClaireRevillet Sandra Siljestroumlm Oliver Stenzel Boris ZaprudinInstitution(s) 1 Center for Space and Habitability (CSH)University of Bern 2 Centre de Sciences Nucleacuteaires et de Sciencesde la Matiegravere - CSNSM CNRSIN2P3-Univ Paris Sud 3Department of Chemistry Materials and Surfaces SP TechnicalResearch Institute of Sweden 4 ESA - ESTEC 5 FinnishMeteorological Institute Climate Research 6 FinnishMeteorological Institute Observation services 7 GraduateInstitute of Astronomy 8 Institut dAstrophysique Spatiale CNRS Universiteacute Paris Sud 9 Institut de Planeacutetologie etdrsquoAstrophysique de Grenoble UMR 5274 Univ Grenoble AlpesCNRS 10 Institut fuumlr Anorganische und Physikalische ChemieUniversitaumlt Bremen 11 Institut fuumlr Planetologie UniversitaumltMuumlnster 12 Institut fuumlr Weltraumforschung OumlsterreichischeAkademie der Wissenschaften 13 Institute of statistics andmathematical methods in economics 14 Laboratoire de Physiqueet Chimie de lEnvironnement et de lEspace CNRS UniversiteacutedrsquoOrleacuteans 15 Laboratory of Molecular Plant Biology Dept ofBiochemistry PharmaCity 16 LISA UMR CNRS 7583 UniversiteacuteParis Est Creacuteteil et Universiteacute Paris Diderot Institut Pierre SimonLaplace 17 Max-Planck-Institut fuumlr extraterrestrische Physik 18Max-Planck-Institut fuumlr Kernphysik 19 Max-Planck-Institut fuumlrSonnensystemforschung 20 Physikalisches Institut UniversitaumltBern 21 RC Seibersdorf Research GmbH Business FieldAerospace Technology 22 Solar System Science OperationDivision ESA-ESAC 23 The University of Chicago Department ofthe Geophysical Sciences 24 Universitaumlt der Bundeswehr LRT-725 Universitaumlt Wuppertal 26 University of Turku Department ofPhysics and Astronomy Tuorla Observatory 27 von Hoerner undSulger GmbH

50309 ndash Three-dimensional kinetic modeling of theneutral and charged dust in the coma of Rosettarsquostarget comet 67PChuryumov-GerasimenkoRosetta is the first mission that escorts a comet along its waythrough the Solar System for an extended amount of time As aresult the target of the mission comet 67PChuryumov-Gerasimenko is an object of great scientific interestDust ejected from the nucleus is entrained into the coma by theescaping gas Interacting with the ambient plasma the dustparticles are charged by the electron and ion collection currentsThe photo and secondary emission currents can also change theparticle charge The resulting Lorentz force together with the gasdrag gravity and radiation pressure define the dust particletrajectoriesAt altitudes comparable to those of the Rosetta trajectory directionof a dust particle velocity can be significantly different from that inthe innermost vicinity of the coma near the nucleus At suchaltitudes the angular distribution of the dust grains velocity has apronounced tail-like structure This is consistent with RosettarsquosGIADA dust observations showing dust grains moving in theanti-sunward directionHere we present results of our model study of the neutral andcharged dust in the coma of comet 67PChuryumov-Gerasimenkocombining the University of Michigan AMPS kinetic particle modeland the BATSRUS MHD model Trajectories of dust particleswithin the observable size range of Rosettarsquos GIADA dust

instrument have been calculated accounting for the radiationpressure gas drag the nucleus gravity the Lorentz force and theeffect of the nucleus rotation The dust grain electric charge iscalculated by balancing the collection currents at the grainrsquoslocation We present angular velocity distribution maps of thesecharged dust grains for a few locations representative of Rosettastrajectory around the cometThis work was supported by US Rosetta project contractsJPL-1266313 and JPL-1266314 and NASA Planetary Atmospheresgrant NNX14AG84G

Author(s) Valeriy Tenishev Dmitry Borovikov Michael RCombi Nicolas Fougere Zhenguang Huang Andre Bieler Kenneth Hansen Gabor Toth Xianzhe Jia Yinsi Shou Tamas Gombosi Martin Rubin Alessandra Rotundi VincenzoDella CorteInstitution(s) 1 INAF Istituto di Astrofisica e PlanetologiaSpaziali 2 Univ of Michigan 3 University of Bern

504 ndash Extrasolar Planets Giant PlanetAtmospheres50401 ndash Saturn as a Transiting ExoplanetPrevious investigations of exoplanet atmospheres have nottargeted those resembling the gas giant planets in our solar systemThese types of exoplanets are too cold to be directly imaged orobserved in emission and their low transit probabilities andfrequencies make characterization via transmission spectroscopy achallenging endeavor However studies of cold giant exoplanetswould be highly valuable to our understanding of planet formationand migration and could place the gas giant members of our ownsolar system in a greater context Here we use solar occultationsobserved by the Visual and Infrared Mapping Spectrometer aboardthe Cassini Spacecraft to extract the 1 to 5 μm transmissionspectrum of Saturn as if it were a transiting exoplanet We detectabsorption features from several molecules despite the presence ofammonia clouds Self-consistent exoplanet atmosphere modelsshow good agreement with Saturns transmission spectrum but failto reproduce the largest feature in the spectrum We also find thatatmospheric refraction determines the minimum altitude thatcould be probed during mid-transit of a Saturn-twin exoplanetaround a Sun-like star These results suggest that transmissionspectroscopy of cold long-period gaseous exoplanets should bepossible with current and future observatories

Author(s) Paul A Dalba Philip S Muirhead Jonathan JFortney Matthew M Hedman Philip D Nicholson Mark JVeyetteInstitution(s) 1 Boston University 2 Cornell University 3University of California Santa Cruz 4 University of IdahoMoscow

50402D ndash Transmission spectral properties of cloudsfor hot Jupiter exoplanetsClouds play an important role in the atmospheres of planetarybodies It is expected that like all the planetary bodies in our solarsystem exoplanet atmospheres will also have substantial cloudcoverage and evidence is mounting for clouds in a number of hotJupiters To better characterise planetary atmospheres we need toconsider the effects these clouds will have on the observedbroadband transmission spectra Here we examine the expectedcloud condensate species for hot Jupiter exoplanets and the effectsof various grain sizes and distributions on the resultingtransmission spectra from the optical to infrared which can beused as a broad framework when interpreting exoplanet spectraWe note that significant infrared absorption features appear in thecomputed transmission spectrum the result of vibrational modesbetween the key species in each condensate which can potentiallybe very constraining While it may be hard to differentiate betweenindividual condensates in the broad transmission spectra it may bepossible to discern different vibrational bonds which candistinguish between cloud formation scenarios such as condensateclouds or photochemically generated species Vibrational mode

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165

features are shown to be prominent when the clouds are composedof small sub-micron sized particles and can be associated with anaccompanying optical scattering slope These infrared featureshave potential implications for future exoplanetary atmospherestudies conducted with JWST where such vibrational modesdistinguishing condensate species can be probed at longerwavelengths

Author(s) Hannah Wakeford David Kent SingInstitution(s) 1 NASA GSFC 2 University of Exeter

50403 ndash Exploring Equilibrium Chemistry for HotExoplanetsIt has been established that equilibrium chemistry is usuallyachieved deep in the atmosphere of hot Jovians where timescalesare short (Line and Young 2013) Thus equilibrium chemistry hasbeen used as a starting point (setting initial conditions) forevaluating disequilibrium processes We explore parameters ofsetting these initial conditions including departures from solarmetallicity the number of species allowed in a system the types ofspecies allowed in a system and different thermodynamic librariesin an attempt to create a standard for evaluating equilibriumchemistry NASAs open source code Chemical Equilibrium andApplications (CEA) is used to calculate model planet abundancesby varying the metallicity in the pressure regime of 01 to 1 barThese results are compared to a variety of exoplanets (Teq between600 and 2100K) qualitatively by color maps of the dayside withdifferent temperature redistributions Additionally CEA (with anupdated thermodynamic library) is validated with thethermochemical model presented in Venot et al (2012) for HD209458b and HD 189733b This same analysis has then beenextended to the cooler planet HD 97658b Spectra are generatedfrom both modelsrsquo abundances using the open source code transit(httpsgithubcomexosportstransit) using the opacities of 15molecules We make the updated CEA thermodyanamic library andsupporting Python scripts to do the CEA analyses available opensource This work was supported by NASA Planetary Atmospheresgrant NNX12AI69G

Author(s) Sarah Blumenthal Joseph Harrington AviMandell Eric Heacutebrard Olivia Venot Patricio Cubillos RyanChallenerInstitution(s) 1 Katholieke Universiteit Leuven 2 NASAGoddard Space Flight Center 3 University of Central Florida

50404D ndash Microphysics of Exoplanet Clouds andHazesClouds and hazes are ubiquitous in the atmospheres of exoplanetsHowever as most of these planets have temperatures between 600and 2000 K their clouds and hazes are likely composed of exoticcondensates such as silicates metals and salts We currently lack asatisfactory understanding of the microphysical processes thatgovern the distribution of these clouds and hazes thus creating agulf between the cloud properties retrieved from observations andthe cloud composition predictions from condensation equilibriummodels In this work we present a 1D microphysical cloud modelthat calculates from first principles the rates of condensationevaporation coagulation and vertical transport of chemicallymixed cloud and haze particles in warm and hot exoplanetatmospheres The model outputs the equilibrium number densityof cloud particles with altitude the particle size distribution andthe chemical makeup of the cloud particles as a function of altitudeand particle mass The model aims to (1) explain the observedvariability in ldquocloudinessrdquo of individual exoplanets (2) assesswhether the proposed cloud materials are capable of forming theobserved particle distributions and (3) examine the role cloudshave in the transport of (cloud-forming) heavy elements inexoplanet atmospheres

Author(s) Peter Gao Bjoumlrn Benneke Heather A Knutson Yuk L YungInstitution(s) 1 Caltech

50405 ndash The Effect of Photochemistry and Quenching

on the Atmospheric Composition of Young DirectlyImaged Giant PlanetsThe last decade has seen significant progress on the directdetection and characterization of young self-luminous giantplanets at wide orbital separation from their host stars Several ofthese planets show evidence for disequilibrium processes liketransport-induced quenching in their atmospheres which affectsthe relative abundances of methane and carbon monoxide and hasother compositional consequences Photochemistry is alsopotentially important on many of these planets despite their largeorbital distance because the young host stars often haveprodigious UV output Disequilibrium chemical processes such asthe above can alter the expected spectroscopic signatures of theplanets and potentially confuse determinations of bulk elementalratios which provide important insights into planet-formationmechanisms We use a thermochemical and photochemicalkinetics and transport model to investigate the effects ofphotochemistry and quenching on young directly imaged planetsResults for specific exoplanets such as the HR 8799 planets and 51Eri b will be presented as will more general trends as a function ofplanet mass orbital distance bulk atmospheric abundances andstellar properties

Author(s) Julianne I Moses Michael R Line ChannonVisscher Mark S Marley Jonathan J Fortney Nikole K Lewis Michael J WolffInstitution(s) 1 Dordt College 2 NASA Ames Research Center3 Space Science Institute 4 Space Telescope Science Institute 5University of California - Santa Cruz

50406 ndash WASP-12b According to the BayesianAtmospheric Radiative Transfer (BART) CodeWe present the Bayesian Atmospheric Radiative Transfer (BART)code for atmospheric property retrievals from transit and eclipsespectra and apply it to WASP-12b a hot (~3000 K) exoplanet witha high eclipse signal-to-noise ratio WASP-12b has beencontroversial We (Madhusudhan et al 2011 Nature) claimed itwas the first planet with a high CO abundance ratio Line et al(2014 ApJ) suggested a high CO abundance to explain the dataStevenson et al (2014 ApJ atmospheric model by Madhusudhan)add additional data and reaffirm the original result stating thatC H and HCN not included in the Line et al models explain thedata We explore several modeling configurations and includeHubble Spitzer and ground-based eclipse dataBART consists of a differential-evolution Markov-Chain MonteCarlo sampler that drives a line-by-line radiative transfer codethrough the phase space of thermal- and abundance-profileparameters BART is written in Python and C Python modulesgenerate atmospheric profiles from sets of MCMC parameters andintegrate the resulting spectra over observational bandpassesallowing high flexibility in modeling the planet without interactingwith the fast C portions that calculate the spectra BARTs sharedmemory and optimized opacity calculation allow it to run on alaptop enabling classroom use Runs can scale constantabundance profiles profiles of thermochemical equilibriumabundances (TEA) calculated by the included TEA code orarbitrary curves Several thermal profile parameterizations areavailable BART is an open-source reproducible-research codeUsers must release any code or data modifications if they publishresults from it and we encourage the community to use it and toparticipate in its development via httpgithubcomExOSPORTSBARTThis work was supported by NASA Planetary Atmospheres grantNNX12AI69G and NASA Astrophysics Data Analysis Program grantNNX13AF38G J Blecic holds a NASA Earth and Space ScienceFellowship

Author(s) Joseph Harrington Patricio E Cubillos Jasmina Blecic Ryan C Challener Patricio M Rojo Nate BLust M Oliver Bowman Sarah D Blumenthal Andrew SDFoster A J FosterInstitution(s) 1 Princeton University 2 UCLA 3 Universidadde Chile 4 University of Central Florida

1 2

3 32 2 1 3

3

1 1 11

3 51 2 5 4

3

2

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1 2 44 4

166

50407 ndash HST hot Jupiter transmission spectralsurvey The atmospheric circulation of a large hotJupiter sampleEven as we move towards characterizing smaller and coolerexoplanets hot Jupiters continue to be the best transiting planetsfor probing the atmospheric properties of exoplanets and refiningcurrent theory Here we present results from a comprehensiveatmospheric circulation study of nine transiting hot Jupiters thatprobe a wide range of planetary properties including orbitaldistance rotation rate mass radius gravity and stellar insolationWe utilize these circulation models to aid in the interpretation oftransmission spectra obtained using the Space Telescope ImagingSpectrograph (STIS) and Wide Field Camera 3 (WFC3) as a part ofa large Hubble Space Telescope (HST) transmission spectralsurvey These observations have shown a range of spectralbehavior over optical and infrared wavelengths suggesting diversecloud and haze properties in their atmospheres Our ldquogridrdquo ofmodels recovers trends shown in other parametric studies of hotJupiters particularly increased day-night temperature contrastwith increasing equilibrium temperature and equatorialsuperrotation Furthermore we show that three-dimensionalvariations in temperature particularly across the western andeastern terminators and from the equator to the pole can vary byhundreds of Kelvin This can result in vastly different cloudproperties across the limb which can lead to variations intransmission spectra Finally we comment on prospects with theJames Webb Space Telescope (JWST) to further characterize hotJupiters out to longer wavelengths

Author(s) Tiffany Kataria David K Sing Nikole K Lewis Jonathan J Fortney Mark S Marley Adam P ShowmanInstitution(s) 1 NASA Ames Research Center 2 SpaceTelescope Science Institute 3 University of Arizona 4 Universityof California at Santa Cruz 5 University of Exeter

50408 ndash Structure and Evolution of Internally HeatedHot JupitersThe transit radii of many close-in extrasolar giant planets or hotJupiters are systematically larger than those expected frommodels considering only cooling from an initial high-entropy stateThough these planets receive strong irradiation with equilibriumtemperatures of 1000-2500 Kelvin the absorption of stellarincident flux in the upper atmosphere alone cannot explain theseanomalous radii More promising mechanisms involve irradiation-driven meteorological activity which penetrates much deeper intothe planet than direct stellar heating This circulation can lead tolarge-scale mixing and downward transport of kinetic energy bothprocesses whereby a fraction of the stellar incident power istransported downwards to the interior of the planet Here weconsider how deposition of heat at different pressure levels orstructural locations within a planet affects the resulting evolutionTo do so we run global gas giant evolutionary models with with thestellar structure code MESA including additional energydissipation We find that relatively shallow atmospheric heatingalone can explain the transit radii of the hot Jupiter sample butheating in the convective zone is an order of magnitude moreefficient regardless of exact location Additionally a smalldifference in atmospheric heating location can have a significanteffect on radius evolution especially near the radiative-convectiveboundary The most efficient location to heat the planet is at theradiative-convective boundary or deeper We expect that shearinstabilities at this interface may naturally explain energydissipation at the radiative-convective boundary which typicallylies at a pressure of ~1 kilobar after 5 Gyr for a planet with the massand incident stellar flux of HD 209458b Hence atmosphericprocesses are most efficient at explaining the bloated radii of hotJupiters if they can transport incident stellar power downwards tothe top of the inner convective zone

Author(s) Thaddeus D Komacek Andrew N YoudinInstitution(s) 1 University of Arizona

505 ndash Marss Atmosphere50501 ndash How relevant is heterogeneous chemistry onMars Strong tests via global mapping of water andozone (sampled via O dayglow)Ozone and water are powerful tracers of photochemical processeson Mars Considering that water is a condensable with amultifaceted hydrological cycle and ozone is continuously beingproduced destroyed on short-time scales their maps can test thevalidity of current 3D photochemical and dynamical modelsComparisons of modern GCM models (eg Lefegravevre et al 2004)with certain datasets (eg Clancy et al 2012 Bertaux et al 2012)point to significant disagreement which in some cases have beenrelated to heterogeneous (gas-dust) chemistry beyond the classicalgas-gas homogeneous reactionsWe address these concerns by acquiring full 2D maps of water andozone (via O dayglow) on Mars employing high spectral infraredspectrometers at ground-based telescopes (CRIRESVLT andCSHELLNASA-IRTF) By performing a rotational analysis on theO lines we derive molecular temperature maps that we use toderive the vertical level of the emission (eg Novak et al 2002)Our maps sample the full observable disk of Mars onMarch252008 (Ls=50deg northern winter) and on Jan292014(Ls=83deg northern spring) The maps reveal a strong dependenceof the O emission and water burden on local orography while thetemperature maps are in strong disagreement with current modelsCould this be the signature of heterogeneous chemistry We willpresent the global maps and will discuss possible scenarios toexplain the observationsThis work was partially funded by grants from NASAs PlanetaryAstronomy Program (344-32-51-96) NASArsquos Mars FundamentalResearch Program (20395902022029) NASArsquos AstrobiologyProgram (344-53-51) and the NSF-RUI Program (AST-805540)We thank the administration and staff of the European SouthernObservatoryVLT and NASA-IRTF for awarding observing time andcoordinating our observationsBertaux J-L Gondet B Lefegravevre F et al 2012 J Geophys ResPl 117 pp 1ndash9Clancy RT Sandor BJ Wolff MJ et al 2012 J Geophys ResPl 117 p E00J10Lefegravevre F Lebonnois S Montmessin F amp Forget F 2004 JGeophys Res Pl 109 pp 1ndash20Novak RE Mumma MJ Disanti MA et al 2002 Icarus 158(1) pp 14ndash23

Author(s) Geronimo Luis Villanueva Michael J Mumma Robert E NovakInstitution(s) 1 Iona College 2 NASA-Goddard Space FlightCenter

50502 ndash Investigating SEP and Auroral Consequencesof the Magnetic Topology Near MarsThe diffuse UV aurora at Mars discovered by MAVENs IUVS hasbeen shown to be caused by solar energetic electrons observed byMAVENs SEP detector but the spatial patterns of these emissionsare still under study In the meantime BATS-R-US models of theMars-solar wind interaction have been shown to describe thein-situ plasma and field observations well to first order We use aset of nominal simulations together with a few case study results toexamine the geometry of the magnetic field line footpoints that areopen-or connected to the interplanetary field- in these models Inaddition the subset of these that are directly connected to the Sunvia the upstream magnetic field are identified We use these resultsfor comparisons with the reported diffuse auroral occurrence mapand to describe what can happen during the passage of an ICMEWe also consider the potential use of these field line tracings forunderstanding the geometry of the SEP ion shadowing at theMAVEN orbital period

5 5 24 1 3

1 1

2

2

2

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167

Author(s) Janet Luhmann Christina O Lee Rob Lillis Davin Larson David L Mitchell Shannon M Curry TakuyaHara Jack Connerney Jared Espley Nick Schneider Chuanfei Dong Yingjuan Ma Bruce M JakoskyInstitution(s) 1 AOSS University of Michigan 2 IGPP UCLA 3LASP University of Colorado 4 NASA GFSC 5 SSL University ofCalifornia Berkeley

50503 ndash Impacts of an Interplanetary Coronal MassEjection and the Crustal Magnetic Fields to theMartian hot O coronaAn interplanetary coronal mass ejection (ICME) is a large amountof mass entrained in the heliospheric magnetic field andpropagating outward from the Sun into the interplanetary mediumUpon arrival at Mars ICMEs interact with its upper atmosphereand ionosphere causing important impacts in the planetaryenvironment In March 2015 a strong solar event was observedand associated with a major ICME The major ICME eventsaroused a chain of events on Mars which were detected by theinstruments onboard Mars Atmosphere and Volatile EvolutioN(MAVEN) The consequences in the upper atmosphere are directlyrelated to the important processes that lead to the atmosphericescape We report here our examinations of the impacts of theMarch 8 ICME event on the Martian hot O corona by using our3D framework which couples the Mars application of the AdaptiveMesh Particle Simulator (M-AMPS) the Mars Global Ionosphere-Thermosphere Model (M-GITM) and the Mars multi-fluid MHD(MF-MHD) model Also we present the effects of the crustalmagnetic fields on the structure of the hot O corona to study theinteresting signatures of the crustal magnetic fields Due to theminimal impacts of the ICME deep in the thermosphere andionosphere where the maximum production of hot O occurs ourmodel results showed a stable hot O corona during and after thepeak ICME event However the structure of the corona wasaffected by the existence of the crustal magnetic fields with adecrease in escape rate

Author(s) Yuni Lee Michael Combi Valeriy Tenishev Stephen BougherInstitution(s) 1 University of Michigen

50504 ndash A Comet Engulfs Mars MAVEN observationsof Comet Siding Springrsquos Effects on the MartianMagnetosphereThe nucleus of Comet C2013 A1 (Siding Spring) passed within135000 km of Mars on Oct 19 2014 Thus the cometary coma andthe plasma it produces washed over Mars for several hoursproducing significant effects in the martian magnetosphere andupper atmosphere We present observations from MAVENrsquosparticles and fields instruments that show the martianmagnetosphere was severely distorted during the cometrsquos passageWe note four specific major effects 1) a variable inducedmagnetospheric boundary 2) a strong rotation of the magneticfield as the comet approached 3) severely distorted and disorderedionospheric fields during the cometrsquos closest approach and 4)unusually strong magnetosheath turbulence lasting hours after thecomet left We argue that the comet had effects comparable to alarge solar storm (in terms of incident energy) and so was afascinating opportunity to explore atmospheric escape MAVENrsquosprimary science objective

Author(s) Jared R Espley Gina A DiBraccio JackConnerney David Brain Jacob Gruesbeck Yasir Soobiah Jasper Halekas Michael Combi Janet Luhmann YingjuanMa Yingdong Jia Bruce JakoskyInstitution(s) 1 Atmospheric Oceanic and Space SciencesDepartment University of Michigan 2 Department of EarthPlanetary and Space Sciences UCLA 3 Department of Physics andAstronomy University of Iowa 4 Laboratory for Atmosphericand Space Physics University of Colorado 5 NASA GoddardSpace Flight Center 6 Space Sciences Laboratory University ofCalifornia

50505 ndash Mars Exospheric Temperature Trends as

Revealed by MAVEN NGIMS MeasurementsThe Martian dayside upper thermosphere and exospheretemperatures (Texo) have been the subject of considerable debateand study since the first Mariner ultraviolet spectrometer (UVS)measurements (1969ndash1972) up to recent Mars Express SPICAMUVS measurements (2004ndashpresent) (eg see reviews by Stewart1987 Bougher et al 2000 2014 Muumleller-Wodarg et al 2008Stiepen et al 2014) Prior to MAVEN the Martian upperatmosphere thermal structure was poorly constrained by a limitednumber of both in-situ and remote sensing measurements atselected locations seasons and periods scattered throughout thesolar cycle Nevertheless it is recognized that the Mars orbiteccentricity determines that both the solar cycle and seasonalvariations in upper atmosphere temperatures must be consideredtogether The MAVEN NGIMS instrument measures the neutralcomposition of the major gas species (eg He N O CO N O NO Ar and CO ) and their major isotopes with a verticalresolution of ~5 km for targeted species and a target accuracy oflt25 for most of these species (Mahaffy et al 2014 2015)Corresponding temperatures can now be derived from the neutralscale heights (especially CO Ar and N ) (eg Mahaffy et al 2015Bougher et al 2015) Texo mean temperatures spanning ~200 to300 km are examined for both Deep Dip and Science orbits over11-February 2015 (Ls ~ 290) to 14-July 2015 (Ls ~ 12) Duringthese times dayside sampling below 300 km occurred from thedusk terminator across the dayside and approaching the dawnterminator NGIMS temperatures are investigated to extract spatial(eg SZA) and temporal (eg orbit-to-orbit seasonal solarrotational) variability and trends over this sampling period Solarand seasonal driven trends in Texo are clearly visible but orbit-to-orbit variability is significant and demands further investigationto uncover the major drivers that are responsible

Author(s) Stephen W Bougher Kirk Olsen Kali Roeten Jared Bell Paul Mahaffy Mehdi Benna Meredith Elrod BruceJakoskyInstitution(s) 1 Goddard Space Flight Center 2 NationalInstitute for Aerospace 3 Univ Colorado 4 Univ of Michigan

50506 ndash MAVEN data-model comparison of theresponse of heavy pick-up ions during extremeconditions at MarsMAVEN has observed multiple interplanetary coronal massejection (ICME) events at Mars showing dramatic enhancementsof heavy ion precipitation into the upper atmosphere Heavy ionprecipitation is the primary driver of sputtering which is believedto be one of the main channels for atmospheric erosion duringearlier epochs of our solar system when the solar activity and EUVintensities were much higher than the present day Using MAVENobservations of extreme solar wind events we simulateatmospheric precipitation using fluid and kinetic models andcompare with MAVEN observations The fluid model reproducesthe observed features in the solar wind density velocity andmagnetic field seen along the MAVEN orbit during the March 8thICME event and the subsequent precipitation shows strongagreement with other published predictions of sputtering inextreme conditions

Author(s) Shannon Curry Janet G Luhmann Chuanfei DDong David Brain Francois Leblanc Ronan Modolo JasperHalekas James McFadden Jack Connerney Jared Espley David Mitchell Davin Larson Takuya Hara Bruce JakoskyInstitution(s) 1 LATMOS UVSQ 2 NASA Goddard SpaceFlight Center 3 UC Berkeley Space Sciences Laboratory 4University of Colorado LASP 5 University of Iowa 6 Universityof Michigan

50507 ndash Initial Results from the MAVEN IUVS EchelleChannelThe study of the evolution of water on Mars includesunderstanding the high D H ratio in the atmosphere and surfacewater today believed to be linked to the historic loss of a largevolume of primordial water (the lighter H escapes faster than theheavier D) Toward this end the IUVS instrument on MAVEN

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contains the first echelle spectrograph to be sent to another planetThe system has a novel optical design to enable long-aperturemeasurements of emission lines in the absence of continuumintended primarily to measure the H and D Ly α emission lines andthereby the DH ratio from the martian upper atmosphere Thesystem also detects the OI 1304 triplet with the three componentlines well resolved The specific scientific goal of the echellechannel is to measure the H and D Ly α emissions and to discoverhow the H and D densities temperatures and escape fluxes varywith location season topography etc Recent IR observationsindicate large variations in the DH ratio in the lower atmospherefrom location to location and possibly seasonal changes[Villanueva et al 2015] HST and MEX measurements of the Hcorona of Mars show large (order of magnitude) changes in the Hexosphere and escape flux with changing seasons andorheliospheric distance [Clarke et al 2014 Chaffin et al 2014] Earlyresults from the echelle channel regarding how these parametersapply to martian deuterium will be presented

Author(s) John T Clarke Majd Mayassi WilliamMcClintock Nick Schneider Justin Deighan Ian Stewart Greg Holsclaw Bruce JakoskyInstitution(s) 1 Boston Univ 2 Univ of Colorado

50508 ndash Mars atmospheric escape constrained usingMAVEN IUVS coronal observationsEvery planetary atmosphere is capped by a corona an extendedextremely tenuous region where collisions are negligible andparticles follow ballistic trajectories At Mars the corona isespecially extended due to the low gravity of the planet and a largenumber of coronal particles are on escaping trajectories Suchescape has played a critical role in the history of the Mars systemlikely removing a substantial fraction of the water initially presenton the planet but the mechanism and magnitude of this escaperemains poorly constrained Currently in orbit at Mars MAVENsImaging Ultraviolet Spectrograph (IUVS) is mapping thedistribution of oxygen and hydrogen above 200 km at a high spatialand temporal cadence revealing a dynamic corona inunprecedented detail Results will be presented demonstrating thatthe H in the corona is not spherically symmetric in its distributionand can potentially be used as a tracer of thermospheric generalcirculation and that non-thermal hot O (in contrast with morespatially confined cold thermal O) is ionospherically sourced witha characteristic energy of 11 eV and responds to solar EUV forcingThese results will be interpreted in terms of their impact on ourcurrent understanding of how atmospheric escape operates todayWe will also discuss how these processes may have acted in thepast to deplete Mars initial water inventory potentially altering theredox balance of the planet and atmosphere through differentialescape of H and O

Author(s) Michael S Chaffin Justin Deighan Jean-YvesChaufray Sonal Jain Ian Stewart Bill McClintock MatteoCrismani Arnaud Stiepen Greg Holsclaw John Clarke Franck Montmessin Frank Eparvier Ed Thiemann PhilChamberlain Nick Schneider Bruce JakoskyInstitution(s) 1 Boston University 2 Laboratoire de PhysiqueAtmospheacuterique et Planeacutetaire (LPAP) 3 LATMOSIPSL 4 NASAGoddard 5 University of Colorado

50509 ndash Structure and variability of the Martianupper atmosphere Ultraviolet dayglow observationsby MAVENIUVSMars has been studied extensively at ultraviolet wavelengthsstarting from Mariner 6 and 7 Mariner 9 and more recently bySPICAM aboard Mars Express The results from thesemeasurements reveal a large variability in the composition andstructure of the Martian upper atmosphere However due to thelack of simultaneous measurements of energy input (such as solarelectromagnetic and particle flux) and limitations in theobservation geometry and data itself this variability is still not fullyunderstoodWe report a comprehensive study of Mars dayglow observations bythe Imaging Ultraviolet Spectrograph (IUVS) aboard the Mars

Atmosphere and Volatile EvolutioN (MAVEN) satellite focusingon vertical and global upper atmospheric structure and seasonalvariability The dayglow emission spectra show features similar toprevious UV measurements at Mars IUVS has detected a secondlow-altitude peak in the emission profile of OI 2972 nmconfirming the prediction that the absorption of solar Lyman alphaemission is an important energy source there We find a significantdrop in thermospheric scale height and temperature between Ls =218deg and Ls = 337 - 352deg attributed primarily to the decrease insolar activity and increase in heliocentric distance The CO UVDpeak intensity is well correlated with simultaneous observations ofsolar 17 - 22 nm irradiance at Mars by Extreme Ultraviolet Monitor(EUVM) aboard MAVEN Variations of the derived CO densityalso exhibit significant persistent global structure with longitudinalwavenumbers 1 2 and 3 in a fixed local solar time frame pointingto non-migrating atmospheric tides driven by diurnal solar heatingWe will present and discuss the variability in Martian UV dayglowits dependence on solar EUV flux and the importance of IUVSobservations in our current understanding of Marsrsquo thermosphere

Author(s) Justin Deighan Sonal K Jain Daniel Y Lo AIan F Stewart Nicholas M Schneider Arnaud Stiepen J ScottEvans Michael H Stevens Roger V Yelle Scott L England Michael Scott Chaffin Matteo Crismani William EMcClintock John T Clarke Greg M Holsclaw FranckLefevre Franck Montmessin Edward MB Thiemann FrankEparvier Bruce M JakoskyInstitution(s) 1 Center for Space Physics Boston University 2Computational Physics Inc 3 Laboratory for Atmospheric andSpace Physics University of Colorado 4 LATMOSCNRS 5Lunar and Planetary Laboratory University of Arizona 6 NavalResearch Laboratory 7 Space Sciences Laboratory University ofCalifornia

506 ndash Comets Physical CharacteristicsDynamics and Composition50601D ndash Comets as natural laboratoriesInterpretations of the structure of the innerheliosphereMuch has been learnt about the heliospherersquos structure from insitu solar wind spacecraft observations Their coverage is howeverlimited in time and space Comets can be considered to be naturallaboratories of the inner heliosphere as their ion tails trace thesolar wind flow Solar wind conditions influence cometsrsquo inducedmagnetotails formed through the draping of the heliosphericmagnetic field by the velocity shear in the mass-loaded solar windI present a novel imaging technique and software to exploit the vastcatalogues of amateur and professional images of comet ion tailsMy projection technique uses the cometrsquos orbital plane to sampleits ion tail as a proxy for determining multi-latitudinal radial solarwind velocities in each cometrsquos vicinity Making full use of manyobserving stations from astrophotography hobbyists toprofessional observatories and spacecraft this approach is appliedto several comets observed in recent years This work thus assessesthe validity of analysing cometsrsquo ion tails as complementary sourcesof information on dynamical heliospheric phenomena and theunderlying continuous solar windComplementary velocities measured from folding ion rays and avelocity profile map built from consecutive images are derived asan alternative means of quantifying the solar wind-cometaryionosphere interaction including turbulent transient phenomenasuch as coronal mass ejections I review the validity of thesetechniques by comparing near-Earth comets to solar wind MHDmodels (ENLIL) in the inner heliosphere and extrapolatedmeasurements by ACE to the orbit of comet C2004 Q2(Machholz) a near-Earth comet My radial velocities are mappedback to the solar wind source surface to identify sources of thequiescent solar wind and heliospheric current sheet crossingsComets were found to be good indicators of solar wind structurebut the quality of results is strongly dependent on the observinggeometry

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Author(s) Yudish Ramanjooloo Geraint H Jones AndrewJ Coates Mathew J OwensInstitution(s) 1 University College London (MSSL) 2University of Hawaii 3 University of Reading (Dept ofMeteorology)

50602D ndash Five years of comet narrow bandphotometry and imaging with TRAPPISTTRAPPIST is a 60-cm robotic telescope in La Silla Observatory [1]mainly dedicated to the study of exoplanets and comets Thetelescope is equipped with a set of narrow band cometary filtersdesigned by the NASA for the Hale-Bopp observing campaign [2]Since its installation in 2010 we gathered a high quality andhomogeneous data set of more than 30 bright comets observedwith narrow band filters Some comets were only observed for a fewdays but others have been observed weekly during several monthson both sides of perihelion From the images we derived OH NHCN C and C production rates using a Haser [3] model inaddition to the Afρ parameter as a proxy for the dust productionWe computed production rates ratios and the dust color for eachcomet to study their composition and followed the evolution ofthese ratios and colors with the heliocentric distanceThe TRAPPIST data set rich of more than 10000 images obtainedand reduced in an homogeneous way allows us to address severalfundamental questions such as the pristine or evolutionary originof composition differences among comets The evolution of cometactivity with the heliocentric distance the differences betweenspecies and from comet to comet will be discussed Finally thefirst results about the one year campaign on comet C2013 US10(Catalina) and our recent work on the re-determination of Haserscalelengths will be presented[1] Jehin et al The Messenger 145 2-6 2011[2] Farnham et al Icarus 147 180-204 2000[3] Haser Bulletin de lrsquoAcadeacutemie Royal des Sciences deBelgique63 739 1957

Author(s) Cyrielle Opitom Emmanuel Jehin JeanManfroid Damien Hutsemeacutekers Michaeumll Gillon PierreMagainInstitution(s) 1 University of Liegravege

50603 ndash Daughter Species Abundances in CometC2014 Q2 (Lovejoy)We present analysis of high spectral resolution optical spectra ofC2014 Q2 (Lovejoy) acquired with the Tull Coude spectrometer onthe 27-meter Harlan J Smith Telescope at McDonald Observatoryand the ARCES spectrometer mounted on the 35-meterAstrophysical Research Consortium Telescope at Apache PointObservatory Both Tull Coude and ARCES provide high spectralresolution (R=30000-60000) and a large spectral range ofapproximately 3500-10000 Angstroms We obtained twoobservation epochs one in February 2015 at a heliocentric distanceof 13 AU and another in May 2015 at a heliocentric distance of 19AU Another epoch in late August 2015 at a heliocentric distance of30 AU is scheduled We will present production rates of thedaughter species CN C CH C and NH We will also presentH O production rates derived from the [OI]6300 emission as wellas measurements of the flux ratio of the [OI]5577 Angstrom line tothe sum of the [OI]6300 and [OI]6364 Angstrom lines (sometimesreferred to as the oxygen line ratio) This ratio is indicative of theCO abundance of the comet As we have observations at severalheliocentric distances we will examine how production rates andmixing ratios of the various species change with heliocentricdistance We will compare our oxygen line measurements toobservations of CO made with Spitzer as well as our otherdaughter species observations to those of candidate parentmolecules made at IR wavelengths

Author(s) Adam McKay Anita Cochran Neil Dello Russo Michael KelleyInstitution(s) 1 Johns Hopkins Applied Physics Laboratory 2University of Maryland 3 University of Texas Austin

50604 ndash A Comprehensive Near-Infrared Spectral

Survey of comet C2014 Q2 (Lovejoy) 09-25 μmIn February 2015 we acquired a comprehensive high resolutionspectral survey of comet C2014 Q2 (Lovejoy) in the 09-25 μmrange with GIANO - the near-IR spectrograph on TNG (the ItalianTelescopio Nazionale Galileo in Canary Island ES) We detectedemission from multiple ro-vibrational bands of H O the redsystem of CN and many other features whose precursors are nowbeing identified We also searched for overtone lines of othervolatiles (eg CH CO and C ) along with OH prompt andfluorescent emissions and atomic carbon prompt emission at98239850 Å These species are relevant to astrobiology owing toquestions regarding the origin of water and organics on terrestrialplanetsComets are the most pristine bodies in the solar system and wateris the most abundant constituent of cometary ice ndash its productionrate is used to quantify cometary activity Along with the waterproduction rate the newly discovered water bands offer theopportunity to measure the ortho-para ratio and nuclear spintemperature with high accuracy in a single instrument settingthereby eliminating many sources of systematic error andpermitting comparisons amongst comets This can clarify thenature and meaning of the spin temperature in the cosmic contextHigh-resolution spectroscopy in the infrared (27 - 5 μm) is awell-established powerful tool for quantifying abundances of tracecompounds and water in cometary comae Implementing thisapproach in the near-IR region (09-25 μm) will extend thiscapability to new band systems and will also reduce thermal noisesignificantlyThese observations open new pathways for cometary science in thenear-infrared spectral range (09-25 μm) and establish thefeasibility of astrobiology-related scientific investigations withfuture high resolution IR spectrographs on 30-m class telescopeseg the HIRES spectrograph on the E-ELT telescope This work ispart of Sara Faggirsquos PhD thesis project

Author(s) Sara Faggi Geronimo Luis Villanueva Michael JMumma John Robert Brucato Gian-Paolo Tozzi ErnestoOlivaInstitution(s) 1 INAF Osservatorio Astrofisico di Arcetri 2NASA Goddard Space Flight Center

50605 ndash The distribution and excitation of CH OH incomet C2012 K1 (PanSTARRS) from ALMAWe present measurements of spatially and spectrally resolvedCH OH emission from the coma of comet C2012 K1(PanSTARRS) observed using the Atacama LargeMillimetersubmillimeter Array (ALMA) in June 2014 TheCH3OH emission is centrally peaked with a spatial profileconsistent with production from the sublimation of ices from thenucleus From the detection of multiple lines of CH OH in theJ=7-6 and K=3-2 bands around 339 and 252 GHz respectively theline-of-sight average rotational excitation temperatures (T ) havebeen derived as a function of spatial position across the coma Atthe CH OH peak we find Trot=92 K falling to about 40 K at adistance of 1000 km The temperature does not fall monotonicallybut shows a double-peaked structure indicative of a heating sourceat distances gt=500 km from the nucleus

Author(s) Stefanie N Milam Martin A Cordiner JeremieBoissier Steven B Charnley Anthony Remijan MichaelMumma Geronimo Villanueva Lucas Paganini DominiqueBockelee-Morvan Jacques Crovisier Nicolas Biver BonchoBonev Yi-Jehng Kuan Dariuz LisInstitution(s) 1 Institut de Radioastronomie Millimetrique 2NASA Goddard Space Flight Center 3 National Radio AstronomyObservatory 4 National Taiwan Normal University 5Observatoire de Paris

50606 ndash Spatial-Spectral Studies of CometaryVolatiles and the Physical Environment of InnerCometary AtmospheresHow is water released in comets - directly from the nucleus versussublimation from icy grains in the coma How common and howprevalent are icy grains as a source of gas-phase water (and other

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volatiles) among the active comet population These questions arebeing addressed through synergy between spatial-spectral studiesof native volatiles in comets and the physical models tested againstthem This synergy is extending the state-of-the-art in bothdomains Ground-based near-IR spectroscopy (Keck NASA IRTFand ESO VLT) allowed measurements of spatially resolved innercoma temperatures and column densities for H2O ndash the mostabundant volatile in the coma These measurements motivated theinclusion of new physics in the models The evolved models nowopen new questions and trigger improvement in the accuracy ofmeasured temperature profiles most recently extended to othermolecules (HCN in the near-IR) and to other wavelength domains(CH3OH through ALMA S Milam et al this meeting) The netresult is deeper quantitative insight into the competition amongprocesses that cause heating and cooling of the coma and into theprevalent mechanism(s) for release of native volatiles in the gasphaseThe same inner-coma modeling formalisms are used to interpretboth the environment of Rosettas mission target(67PChuryumovndashGerasimenko) and those from theground-based observations reported here (Combi et al 2015LPSC 1714 Fougere et al this meeting) While ground-basedspectroscopy offers less detail than in-situ missions it can probethe comae of many comets that may differ greatly from one anotherand from Rosettas target thereby assessing the extent to which theinner-coma environment of 67P is unique and how it relates toother cometsWe gratefully acknowledge support from NASA PlanetaryAtmospheres Solar System Workings Planetary Astronomy andAstrobiology programs and from NSF Astronomy and AstrophysicsResearch Grants program

Author(s) Boncho P Bonev Nicolas Fougere Geronimo LVillanueva Michael J Mumma Michael R Combi Michael ADiSanti Lucas Paganini Martin Cordiner Erika L Gibb Stefanie N MilamInstitution(s) 1 Catholic University of America 2 NASAGoddard Center for Astrobiology 3 University of Michigan 4University of Missouri - St Louis

50607 ndash Lightcurves and revised masses of the largeparticles at comet 103PHartley 2Comet 103PHartley 2 is a hyperactive comet Such comets havenuclei with surface areas comparable to the surface area required tosustain their water production rates implying the surface is near100 active However images of the nucleus and inner coma bythe Deep Impact Flyby spacecraft show signficant localized activitydominated by a single strong active area (AHearn et al 2011Science 332 1396) This active area seems to be driven by carbondioxide ice sublimation which releases water ice into the coma(Protopapa et al 2014 Icarus 238 191) It has been hypothesizedthat this water-ice-rich material is the origin of the cometshyperactivity but this has not yet been definitively demonstratedThe Deep Imact spacecraft also imaged thousands of point sourcessurrounding the nucleus of the comet (AHearn et al 2011) Thesesources are particles ejected by the comet the largest of which isestimated to have a radius between 30 and 400 cm The wide rangein the radius estimate is due to the unknown photometricproperties of the particles If the particles are icy they maycontribute a significant fraction of the comets water productionrate (Kelley et al 2013 Icarus 222 634)To better elucidate the physical properties of the particles wegenerated particle lightcurves based on the identifications ofHermalyn et al (2013 Icarus 222 625) and a an independent(manual) particle search We find no clear correlation with time orphase angle suggesting the lightcurves are primarily driven byparticle shape rather than sublimation fragmentation or phaseeffects Three lightcurves are double-peaked indicating rotationperiods near 75 to 300 s At least one other lightcurve suggests arotation period of order 20 sWe also present corrections to the analysis of Kelley et al (2013)that decrease the total large particle population mass estimates bytwo orders of magnitude Despite the revision the large particlesmay still account for the comets hyperactivity if they are more likethe low-albedo ice-rich nucleus rather than high-albedo icy grains

However an understanding of the large particle production rate isneeded before definitive statements may be made

Author(s) Michael S Kelley Tony L Farnham BrendanHermalyn Dennis Bodewits Michael F AHearnInstitution(s) 1 NASA Ames Research Center 2 Univ ofMaryland

50608 ndash Volatile Abundance and Distribution in theTempel 1 Ejecta CloudOn 4 Jul 2005 the Deep Impact Impactor Spacecraft collided withcomet Tempel 1 creating an ejecta cloud that was observed by theDeep Impact Flyby Spacecraft (DIF) as well as Earth and spacebased observatories The High Resolution Instrument InfraredSpectrometer (HRI-IR) onboard DIF acquired several spectralscans of this ejecta cloud in the minutes immediately after impactHRI-IR has a spectral range of 105 to 485 microns This spectralrange allows for water vapor water ice organics CO and CO to bedetected simultaneously if each species is sufficiently abundantWe present an analysis of the quantity and spatial distribution ofwater organics and CO in the Tempel 1 ejecta cloud Variation inabundance either absolute or relative will be compared tomorphological features in the ejecta cloud present in visible imagesacquired by the Medium and High Resolution Imagers onboardDIF The composition of the ejecta cloud will also be compared withthat of the 2 Jul 2005 natural outburst and quiescent activity levelsat Tempel 1

Author(s) Mark J Moretto Lori M Feaga Michael FAHearn Silvia Protopapa Jessica M Sunshine Tony LFarnhamInstitution(s) 1 University of Maryland

50609 ndash A Preliminary Analysis of Cometary Dust inthe 1 Year of the NEOWISE Restarted MissionAs some of the most pristine objects in the Solar System cometspresent an opportunity to understand the mechanics and chemistryof the planetary formation era By studying a large number ofcomets in different dynamical classes we can better understand theensemble properties of the different classes and begin tocharacterize the evolution that may have occurred since theirformationIn late 2013 the WISE spacecraft was brought out of hibernationand renamed NEOWISE with a renewed goal to detect andcharacterize small bodies using its 34 and 46-micron bandsSurvey operations began in December 2013 [1] and the first year ofdata was publicly released in March 2015 [2] During the course ofthe first year of the restarted mission over 60 comets wereserendipitously detected by NEOWISE at heliocentric distancesbetween ~1-75 AU including 3 newly discovered comets Thecomets detected were split roughly evenly between short-periodand long-period comets and many displayed extended duststructures Several of the comets were detected multiple times overthe course of the year and some were also seen during the primeWISE mission This long baseline allows for an intriguing analysisof long-term cometary behaviorNEOWISE has sampled the behavior of these comet dynamicalsub-types over the thermal infrared and near-infraredreflected-light regimes where effects from different particle sizeranges of dust may dominate the morphologies and observedfluxes We present a preliminary analysis of the cometary dust seenin these data including dynamical models to constrain the sizesand ages of the dust particles We discuss how these resultscompare to those obtained for the comets seen in the 12 and22-micron WISE prime mission dataAcknowledgments This publication makes use of data productsfrom (1) WISE which is a joint project of UCLA and JPLCaltechfunded by NASA and (2) NEOWISE which is a project ofJPLCaltech funded by the Planetary Science Division of NASAEK RS and SS gratefully acknowledge support from the NASAPostdoctoral Program References [1] Mainzer A et al 2014ApJ 7921 [2] Cutri R et al 2015 httpwise2ipaccaltechedudocsreleaseneowiseexpsup

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Author(s) Emily A Kramer James M Bauer Yanga RFernaacutendez Amy K Mainzer Tommy Grav Joseph R Masiero Carolyn R Nugent Sarah Sonnett Roc Cutri RachelStevensonInstitution(s) 1 Infrared Processing and Analysis Center 2 JetPropulsion Laboratory 3 Planetary Science Institute 4University of Central Florida

50610 ndash Is comet 19PBorrelly changing its spin stateWe observed comet 19PBorrelly from September 6-12 and October9-14 2014 at the SOAR telescope in Chile The comet was atheliocentric and geocentric distances of 29 AU and 22 AU inSeptember and of 27 AU and 24 AU in October We carried outlightcurve observations to derive an accurate rotation period to becompared with that derived by Mueller et al (2010 Icarus 209745) from observations of the 20002001 apparitionThe ultimate goal for these and lightcurve observations of othercomets is to derive changes in the rotation period to test whetherthe changes are really independent of the active fraction as seen forfour other comets (Samarasinha and Mueller 2013 ApJL 775article id L10) Establishing such a correlation will enable theprediction of rotational changes for other comets as well It will alsohave far reaching implications for nuclear activity and itscharacteristics as well as for understanding the reaction torquesdue to outgassingWe gratefully acknowledge support for this work from NASA PASTgrant NNX14AG73G

Author(s) Beatrice E A Mueller Nalin H SamarasinhaInstitution(s) 1 Planetary Science Institute

50611 ndash 322PSOHO 1 Sunskirting Comet orAsteroidComet 322PSOHO 1 (P1999 R1) is a unique object a short periodcomet (P = 399 yr) on a ldquosunskirting orbitrdquo (q = 0053 AU or ~11solar radii) with no dynamical linkage to any other known comets322P was discovered in SOHO images in 1999 and has been seenby SOHO on every subsequent orbit 2003 2007 and 2011 (it isexpected to be observed by SOHO again during its next perihelionpassage in 2015 September) During this time it has not displayedan obvious coma or tail in SOHO images but has exhibited anon-asteroidal lightcurve that strongly suggests the presence of anunresolved coma Equilibrium temperatures during theseobservations exceed 1000 K so it is unclear if 322P is active due tosublimation of volatile ices like a typical comet or if it is anotherwise inactive object that is losing material through moreexotic processes such as sublimation of refractory materials orthermal fracturing Due to the very large uncertainty in orbitsderived from SOHO observations and 322Prsquos assumed small size2015 was the first reasonable opportunity to recover it at largeheliocentric distance and attempt to determine its heritagetraditional comet or asteroid We recovered 322P on 2015 May 22with the VLT and observed it again on five epochs in June and Julywith Spitzer the VLT and the Discovery Channel Telescope Theseare the first successful observations of any SOHO-discovered shortperiod comet at traditional cometary distances 322P appearedpointlike in all images (heliocentric distances from 21 to 12 AU)implying an inactive object having a diameter of a few hundredmeters We will report on these observations focusing onconstraining properties of 322P such as activity level color andalbedo that may help us deduce whether or not it is of a cometaryor asteroidal origin

Author(s) Matthew M Knight Alan Fitzsimmons MichaelS P Kelley Colin SnodgrassInstitution(s) 1 Lowell Observatory 2 Queens UniversityBelfast 3 The Open University 4 University of Maryland

507 ndash Origins of Planetary Systems50701D ndash Collisional properties and dynamicalaccretion of centimeter-sized protoplanetesimalsThe seeds of planetesimals that formed in the turbulent gaseous

environment of the nascent protoplanetary disk have manybarriers to overcome in their growth from millimeter to meter-sizedand larger objects such as collisional disruption and orbital decayCentimeter-sized agglomerates can be weakly bound and quitefragile and at these sizes self-gravity is almost non-existentElectrostatic surface forces such as van der Waalrsquos forces play acritical role in holding loosely bound rubble-piles together Wewish to further understand the mechanical material collisionalproperties and outcomes of collisions between cm-sizedrubble-piles at low speeds that may lead to accretion Thecollisional outcomes can be determined by a set of definablecollision parameters and experimental constraints on theseparameters will improve formation models for planetesimals Wehave carried out a series of laboratory microgravity collisionexperiments of small aggregates to determine under whatconditions collisional growth can occur using mm-sized silica beadsand SiO dust as simulants In our free-fall chambers we obtaincollision velocities ranging from 1 to 200 cm s for 1-2 cmaggregates with pressures ~01 mbars We measure coefficients ofrestitution sticking thresholds and fragmentation thresholdsthen compare the results of our experiments with numericalsimulations using a collisional N-body code We find that cm-sizedagglomerates made up of mm-sized particles (or of mm-sizedaggregates of micron sized SiO dust) are very weakly bound andrequire high porosity and internal cohesion to avoid fragmentationin agreement with both simulations and collision experiments Thevelocity threshold for sticking is found to be near 7 cm s far fromthe fragmentation threshold of ~1 m s for cm-sized bodiesQuiescent regions in the mid-plane of the disk may cultivateabnormally low relative velocities permitting sticking to occur (~1cm s ) however without a well-defined path to formation it isdifficult to determine whether collisional accretion as a mechanismcan overcome low thresholds for sticking and fragmentation Wediscuss this researchrsquos implications to both the meter-barrier andplanetesimal formation

Author(s) Akbar Whizin Joshua E Colwell Juumlrgen Blum Mark C LewisInstitution(s) 1 Technische Universitaumlt Braunschweig 2Trinity University 3 University of Central Florida

50702 ndash Global Evolution of Solids in the Nebula theRole of Porosity in Particle Growth and RadialMigrationPrimitive chondrite parent bodies apparently accreted over severalMyr during which time the nebula gas is expected to have evolvedsignificantly The extended range of radioisotope ages observed forprimitive body formation can then best be explained if the nebulawere weakly turbulent this environment frustrates planetesimalformation but millimeter-to-meter-size particles can grow bysticking and possibly undergo substantial inward radial migrationbefore being destroyed by mutual collisions or evaporating in awarmer environment This migration can lead to a significantredistribution of the nebula condensibles relative to the evolvinggas challenging the popular concepts of minimum mass nebulaand local cosmic abundance Moreover as drifting particlestransform from solid to vapor at evaporation fronts they canfundamentally change the nebula chemical and isotopiccomposition Yet the problem of primary accretion remainscomplicated because although even moderate turbulence canextend the period of accretion over those implied by the meteoriterecord it may do so too well Estrada et al (2015 submitted to ApJarXiv150601420) have found that particle sizes are so readilyrestricted by the combination of bouncing fragmentation andradial drift over the range of models studied that much of thenebula solids can be removed from the outer portions of the diskand become concentrated in the inner regions in relatively shorttimescales where they may eventually be lost altogether The rapidclearing of the outer disk is due to growth not being fast enough toovercome the radial drift barrier However only solid particles wereconsidered Fractal growth by low velocity sticking of smallmonomers will cause the particles to have a much lower densitythan the monomers themselves Coupled with the stickiness andstrength of icy particles we expect that these fluffy aggregates can

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grow large but maintain low relative velocities allowing forcontinued growth without compaction Here we assess whether theconsideration of particle porosity particularly outside the snowline may allow for particles to overcome the radial drift barrier andpotentially grow into larger bodies

Author(s) Paul R Estrada Jeffrey N CuzziInstitution(s) 1 NASA Ames Research Center 2 SETI Institute

50703D ndash Planetary growth by the accretion ofpebblesPebbles approximately cm-sized solids that drift through aprotoplanetary disc provide a reservoir of material that can beefficiently accreted by planetary embryos due to the dissipatingeffect of gas drag (Lambrechts amp Johansen 2012)Here we will highlight the robust implications of pebble accretionon the formation of planets throughout the protoplanetary discIn the outer disc icy pebbles form by coagulation and consequentlystart drifting inwards Nevertheless we find that the pebble surfacedensities are sufficiently high to form giant planets on wide orbitsbefore the gas disc disperses after a few Myr (Lambrechts ampJohansen 2014) Growth is only halted when cores reach sizes ofaround 10 Earth masses when their gravity creates pressurebumps trapping the inwards drifting pebblesThis accretion cutofftriggers the attraction of a massive gaseous envelope Additionallythe fast growth of giant planets prevents the loss of the cores bytype-I migration (Lambrechts et al 2014 Bitsch et al 2015)Closer to the star interior to the ice line pebble accretion takes ona different form There chondrule-sized particles lead to theformation of much smaller Mars-sized embryos before the pebbleflux is terminated by the growth of the gas giants (Morbidelli et al2015) We will also discuss ongoing work on the conditions underwhich much larger Super-Earths can form

Author(s) Michiel Lambrechts Anders Johansen BertramBitsch Alessandro MorbidelliInstitution(s) 1 Lund University 2 Observatoire de la CocirctedAzur

50704 ndash Early Solar System Leftovers Testing SolarSystem Formation ModelsOne of the most intriguing predictions of the Grand Tack model isthe presence of volatile poor objects in the Oort cloud that wereswept from the region where the terrestrial planets formed Thisvolatile-poor material is represented today by ordinary chondritesenstatite chondrites and differentiated planetesimals These are themain constituents of the S-type asteroids that reside in the innerSolar system According to the Grand Tack model the fraction ofS-type material in cometary orbits should be around 01-02Recent Pan-STARRS 1 discoveries of objects on long-period cometorbits that are minimally active while at small perihelia havesuggested the intriguing possibility that these could potentiallyrepresent inner solar system material that was ejected into theouter solar system during planet migration that is now making itsway back in The first object discovered C2013 P2 has a spectrumredder than D-type objects but exhibits low-level activitythroughout its perihelion passage The second one C2014 S3appears to have an S-type asteroid spectrum and likewise exhibitslow-level activityNearly 100 of these objects have now been identifiedapproximately half of which are still observable and more are beingdiscovered We will report on observations made for a selection ofthese objects with several facilities including Gemini N 8 m VLT 8m Canada-France-Hawaii 36 m PS1 2 m UH22 m HCT 2 m andthe Lowell 18 m telescopes We will discuss the implications ofseeing volatile activity in these objects

Author(s) Karen Jean Meech Bin Yang Jan Kleyna Olivier R Hainaut Jacqueline V Keane Marco Micheli Svetlana Berdyugina Bhuwan Bhatt Devendra Sahu HenryHsieh Peter Veres Richard J Wainscoat Timm-EmanuelRiesen Heather KalunaInstitution(s) 1 European Southern Observatory 2 IndianInstitute of Astrophysics 3 Institute for Astronomy 4 Institute ofAstronomy amp Astrophysics Academia Sinica 5 Kiepenheuer-Institut fur Sonnenphysik 6 SSA NEO Coordination Centre ESA7 University of Bern

50705 ndash The effects of the formation of a giant planeton the evolution of the protoplanetary disk the caseof Jupiter in the Solar SystemThe formation of a giant planet is one of the milestones in the lifeof a planetary system as it plays a leading role in shaping itssubsequent evolution Once the core of the forming giant planetreaches the critical mass needed to trigger the hydrodynamicalinstability in the surrounding nebular gas and start the rapid phaseof gas accretion the planetary system in which the planet isembedded suddenly experience the appearance of a stronggravitational perturber Even in absence of migration this eventwill trigger a 05-1 Myr-long phase of violent remixing andenhanced collisional evolution of the planetary bodies in theprotoplanetary disk For what it concerns the giant planet itselfthis primordial bombardment will result in the capture of high-Zmaterial from a wide orbital range including the inner regions ofthe planetary system For what it concerns the other bodies of theprotoplanetary disk this phase of remixing and bombardment willresult in the collisional erosion of the smallest planetesimals in thedynamically-excited orbital regions and in the delivery of water andvolatile elements to the inner regions of the planetary systemWhile the mass growth of the giant planet is necessary andsufficient condition to trigger this primordial bombardmentplanetary migration plays a major role in determining its intensityUsing the formation of Jupiter in the Solar System as our casestudy we will illustrate how this event affects the Jovian systemand the asteroid belt Concerning the latter we will also discusshow the composition of asteroid Vesta whose formation anddifferentiation predate the formation of Jupiter suppliesinformation on the primordial dynamical evolution of the giantplanet

Author(s) Diego TurriniInstitution(s) 1 Institute for Space Astrophysics andPlanetology INAF-IAPS

50706 ndash In-situ Formation of Mars-like Planets -Results from Hundreds of N-body Simulations ThatInclude Collisional FragmentaionDynamical simulations of the formation of the Solar System havebeen successful at reproducing the broad characteristics of theterrestrial planets however they have consistently struggled toreproduce the small mass of Mars within the timescale provided bygeochemical constraints This has prompted the development ofnew models that invoke various mechanisms such as giant planetmigration that result in the formation a small Mars Due primarilyto the computationally intensive nature of these models mostprevious studies were based on a small (less than a dozen) numberof simulations and did not include the effects of collisionalfragmentation However these systems are highly stochastic andrequire a large number of simulations in order to infer the resultsin a statistical manner Here we show that by performing 150N-body simulations of terrestrial planet formation around the Sunthat include collisional fragmentation the formation ofMars-analogs is a natural outcome albeit not a common oneApproximately 13 of the simulations produced a Mars-sizedplanet near Marsrsquo current orbit that accreted at least 90 of itsmass within 3 Myr The current architecture of the planets in ourSolar System can be thought of as one draw from a distribution ofplanetary systems that can form from essentially the sameprotoplanetary disk These results support the idea that Mars mayessentially be a stranded embryo that survived the giant impactphase without a significant amount of accretion or erosion but that

2 1

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it need not be the only outcome from the chaotic process offorming planets

Author(s) Thomas Barclay Elisa V QuintanaInstitution(s) 1 NASA Ames Research Center

50707 ndash Determining the Location of the Snowline inan Externally-Photoevaporated Solar NebulaThe water snowline in the solar nebula the point beyond whichwater exists abundantly as ice is often taken to lie at 27 AU fromthe Sun where temperatures are ~170 K the sublimation point ofwater [12] While superficially consistent with the spatialdistribution of (wet) C-type and (dry) S-type asteroids between2-3AU [3] most disk models place the snowline closer to ~1AU [4]Aside from temperature radial transport and outward diffusion ofwater vapor and the inward drift of ices also determine where thesnowline is [56] Over many Myr a steady cycling of water inwardand outward across the T=170 K line balance out with anenhanced ice abundance outside creating the lsquosnowlinersquo[2] Butexternal effects like photoevaporation of the nebula by nearbymassive stars can potentially shift this balance lead to net outwardwater vapor transport from the inner nebula [78] pushing thesnowline beyond T=170 K thus giving rise to water-poor planetsTo test this hypothesis we have first built a 1+1D protoplanetarydisk evolution model incorporating viscosity due to themagnetorotational instability with a non-uniform turbulentviscosity α across disk radius r ionization equilibrium with dustand external photoevaporation [8] Our simulation results suggestthat the structure of the photoevaporated solar nebula with anon-uniform α(r) was more complex than previously thought withthe following features (i) very steep Σ profile (Σ(r)=Σ r whereslope p = 3ndash5 gt p =15) due to the varying α(r) that isfurther steepened by the effect of dust and photoevaporation and(ii) transition radius (where net disk mass flow changes frominward flow to outward) that is present very close to the star(~3AU) We apply these new results to study the distribution ofwater in the solar nebula References [1] Hayashi C (1981)PThPSupp 70 35-53 [2] StevensonD amp LunineJ (1988) Icarus75 146-155 [3] Gradie J amp Tedesco E(1982) Science 2161405-1407 [4] Sasselov DD amp Lecar M (2000) ApJ 528995-998 [5] Cuzzi J N amp Zahnle K J (2004) ApJ 614 490-496[6] Ciesla F J amp Cuzzi J N (2006) Icarus 181 178-204 [7]Desch SJ(2012)LPSC abstract 2770 [8] Kalyaan A et al(inreview)

Author(s) Anusha Kalyaan Steven DeschInstitution(s) 1 Arizona State University

50708 ndash Nebular dead zone effects on the DH ratio inchondrites and cometsComets and chondrites show non-monotonic behaviour of theirDeuterium to Hydrogen (DH) ratio as a function of theirformation location from the Sun This is difficult to explain with aclassical protoplanetary disk model that has a decreasingtemperature structure with radius from the SunWe want to understand if a protoplanetary disc with a dead zone aregion of zero or low turbulence can explain the measured DHvalues in comets and chondrites We use time snapshots of avertically layered disk model with turbulent surface layers and adead zone at the midplane The disc has a non-monotonictemperature structure due to increased heating from self-gravity inthe outer parts of the dead zone We couple this to a DH ratioevolution model in order to quantify the effect of such thermalprofiles on DH enrichment in the nebulaWe find that the local temperature peak in the disk can explain thediversity in the DH ratios of different chondritic families This disktemperature profile leads to a non-monotonic DH enrichmentevolution allowing these families to acquire their different DHvalues while forming in close proximity The formation order weinfer for these families is compatible with that inferred from theirwater abundances However we find that even for very youngdisks the thermal profile reversal is too close to the Sun to berelevant for comets[1] Ali-Dib M Martin R G Petit J-M Mousis O Vernazza P

and Lunine J I (2015 in press AampA) arXiv150800263

Author(s) Mohamad Ali-Dib R G Martin J-M Petit OMousis P Vernazza J I LunineInstitution(s) 1 Aix Marseille Universiteacute CNRS LAM(Laboratoire drsquoAstrophysique de Marseille) UMR 7326 2 Centerfor Radiophysics and Space Research Space Sciences BuildingCornell University 3 Department of Physical amp EnvironmentalSciences University of Toronto at Scarborough 4 Department ofPhysics and Astronomy University of Nevada 5 Universiteacute deFranche-Comteacute Institut UTINAM CNRSINSU UMR 6213Observatoire de Besanccedilon

50709 ndash C O (x=161718) isotopologue ratios in thesolar photosphereDetermination of the oxygen isotope ratios in the solarphotosphere is essential to constraining the formationenvironment of the solar system The solar CO fundamental andfirst-overtone bands were previously measured by theshuttle-borne ATMOS Fourier transform spectrometer (FTS) andwith the National Solar Observatory FTS on the McMath-Piercetelescope at Kitt Peak Analyzing the rovibrational bands fromthese photospheric spectra a 3D convection model was employedto calculate ratios with improved uncertainties( O O=2738plusmn118 and O O =511plusmn10 Ayres et al 2013)which fall between the terrestrial values and those inferred fromsolar wind measurements by the Genesis spacecraft Howeverdifferences in published CO dipole moment functions yielded arange of isotopic ratios spanning ~ 3 in δ O Here were-evaluate the CO dipole moment function in order to obtain moreaccurate isotope ratios for the photosphere We used a new set ofdipole moments from HITEMP which were accurately determinedby both semi-empirical and ab initio methods Preliminary valuesof isotope ratios using the new dipole moments are in betteragreement with the inferred photosphere values from Genesisshowing that the solar photosphere is isotopically similar toprimitive inclusions in meteorites but different from the terrestrialplanets by ~ 6 New spectral observations are needed to reduceuncertainties in photospheric C O abundances

Author(s) James Lyons Ehsan Gharib-Nezhad ThomasAyresInstitution(s) 1 Arizona State University 2 University ofColorado

50710 ndash Consolidating and Crushing Exoplanets DidIt Happen HereKepler revealed the common existence of tightly-packedsuper-Earth systems around solar-type stars existing entirelyinside the orbit of our Venus Those systems must be stable for theages of their host stars (~10^9 years) their formation mechanismmust provide inter-planet spacings that permit long-term stabilityIf one postulates that most planetary systems form with tightly-packed inner planets their current absence in some systems couldbe explained by the collisional destruction of the inner system aftera period of meta-stabilityWe posit that our Solar System also originally had a system ofmultiple planets interior to the orbit of Venus This would resolve aknown issue that the energyangular momentum of our inner-planet system is best explained by accreting the current terrestrialplanets from a disk limited to 07-11 AU in our picture the diskmaterial closer to the Sun also formed planets but they have sincebeen destroyed By studying the orbital stability of systems like theknown Kepler systems we demonstrate that orbital excitation andcollisional destruction could be confined to just the inner parts ofthe system In this scenario Mercury is the final remnant of theinner systems destruction via a violent multi-collision (andorhit-and-run disruption) process This would provide a naturalexplanation for Mercurys unusually high eccentricity and orbitalinclination it also fits into the general picture of long-timescalesecular orbital instability with Mercuryrsquos current orbit beingunstable on 5 Gyr time scales The common decade spacing ofinstability time scales raises the intriguing possibility that thisdestruction occurred roughly 06 Gyr after the formation of our

1 1

0 -p

MMSN

1 1

3 4 51 1 2

x

16 17 16 18

18

17

1 12

174

Solar System and that the lunar cataclysm is a preserved record ofthis apocalyptic event that began when slow secular chaosgenerated orbital instability in our former super-Earth system

Author(s) Brett Gladman Kathryn VolkInstitution(s) 1 Univ of British Columbia

50711 ndash Exoplanet Population Estimate from KeplerDataThe intrinsic population of exoplanets around Kepler target stars isestimated by comparing the observed numbers of planets at eachradius and period against a simulation that accounts for theprobability of transit and the estimated instrument sensitivity Byassuming that the population can be modeled as a function ofperiod times a function of radius and further assuming that thesefunctions are broken power laws sufficient leverage is gained suchthat the well-measured short-period planet distribution caneffectively be used as a template for the less-well sampledlong-period terrestrial planets The resulting populationdistribution provides a challenge to models of the origin andevolution of planetary systems

Author(s) Wesley A TraubInstitution(s) 1 Jet Propulsion Laboratory

508 ndash Icy Satellites50801 ndash From One Come Many A diversity of craterpopulations from a single impacting population withapplication to the Saturnian (and Galilean) SatellitesWe present our recent analyses that quantify the spatial andsize-frequency distribution (SFD) of crater populations on themid-sized Saturnian (and Galilean) satellites The resultsdemonstrate that a single-sized impactor will generate both (i)different-sized primary craters on the icy satellites and (ii)observably different secondary crater populations (both in terms ofSFDs and spatial distributions) between the satellitesRelative magnitude of secondaries and their SFDs The number ofsecondary craters generated by a primary impact is a function of thesize of the primary crater v_min the minimum speed needed tomake a secondary and v_esc the escape speed of the target bodyThe primary crater size controls the amount of ejected materialv_min defines the lower limit of that ejected mass that can makesecondaries and v_esc defines the upper limit of the mass that canmake secondaries (ie material that escapes the target body cannotmake secondaries) Because a single-sized impactor will makedifferent-sized primaries on each of the satellites (resulting indifferent masses available to make secondaries) and v_esc alsovaries between the satellites different amounts of ejecta areavailable to make secondaries Because surface gravity is a factor inthe size of a crater a given-sized ejecta fragment will make adifferent-sized secondary on the satellites even given the sameimpact speedSpatial distribution of secondaries Because of varying surfacegravities g of planetary bodies a given ejectum speed will launch afragment different distances In conjunction with v_min thespatial density of adjacent secondaries (or even their existence) willvary depending on surface gravity At progressively smaller gv_min results in greater distances and dense annular clusterssurrounding the primary crater wonrsquot appear except for the largestprimary craters On the lower-g objects v_min corresponds totravel distances that are significant fractions of the objectrsquoscircumference Ejecta that make adjacent secondaries on a higher-gobject may make a significant population of backgroundsecondaries on low-g objects

Author(s) Edward B Bierhaus Luke Dones StuartRobbinsInstitution(s) 1 Lockheed Martin 2 Southwest ResearchInstitute

50802 ndash Crustal Failure in Large Icy Bodies from aStrong Tidal Encounter

Close tidal encounters among large planetesimals and satellites aremore common than grazing or direct impacts Using a mass springmodel simulation we look at the deformation of the surface of anelastic spherical body caused by a nearly parabolic close tidalencounter with a body that has mass similar to that of the primarybody We delineate a regime for tidal encounters that inducesufficient stress on the surface for brittle failure of an icy crustSimulated cracks caused by extension of the crust extend a largefraction of the radius of body Tidal encounters give an alternativemechanism for formation of long graben complexes and chasma onicy satellites such as Dione Tethys Ariel and Charon

Author(s) Alice C Quillen David Giannella John ShawInstitution(s) 1 Laboratory for Laser Energetics 2 Univ ofRochester

50803 ndash Discovering sub-micron ice particles acrossDione surfaceWater ice is the most abundant component of Saturnrsquos mid-sizedmoons However these moons show an albedo asymmetry ndash theirleading sides are bright while their trailing side exhibits darkterrains Such differences arise from two surface alterationprocesses (i) the bombardment of charged particles from theinterplanetary medium and driven by Saturnrsquos magnetosphere onthe trailing side and (ii) the impact of E-ring water ice particles onthe satellitesrsquo leading side As a result the trailing hemisphereappears to be darker than the leading side This effect is particularlyevident on Diones surface A consequence of these surfacealteration processes is the formation or the implantation ofsub-micron sized ice particlesThe presence of such particles influences and modifies thesurfaces spectrum because of Rayleigh scattering by the particlesIn the near infrared range of the spectrum the main sub-micronice grains spectral indicators are (i) asymmetry and (ii) long wardminimum shift of the absorption band at 202 μm (iii) a decreasein the ratio between the band depths at 150 and 202 μm (iv) adecrease in the height of the spectral peak at 26 μm (v) thesuppression of the Fresnel reflection peak at 31 μm and (vi) thedecrease of the reflection peak at 5 μm relative to those at 36 μmWe present results from our ongoing work mapping the variationof sub-micron ice grains spectral indicators across Dione surfaceusing Cassini-VIMS cubes acquired in the IR range (08ndash51 μm)To characterize the global variations of spectral indicators acrossDione surface we divided it into a 1degx1deg grid and then averaged theband depths and peak values inside each square cellWe will investigate if there exist a correspondence with water iceabundance variations by producing water ice absorption banddepths at 125 152 and 202 μm and with surface morphology bycomparing the results with ISS color maps in the ultraviolet visibleand infrared ranges Finally we will compare the results with thoseobtained for Enceladus Tethys and Mimas

Author(s) Francesca Scipioni Pual Schenk FedericoTosi Roger Clark Cristina Dalle Ore Jean-Philippe CombeInstitution(s) 1 Bear Fight Institute 2 INAFIAPS 3 Lunarand Planetary Institute 4 PSI 5 SETI

50804 ndash High energy electron processing of icyregoliths on Saturns moonsA unique space weathering phenomenon has been identified onseveral icy Saturnian moons Cassini revealed anomalous lensshaped regions in both optical and thermal wavelengthscolloquially known as the PacMan feature which are centered onthe leading hemispheres and approximately symmetric about theequators In particular the Cassini InfraRed Spectrometer (CIRS)measurements of thermal emission in the mid-IR showed thatsurface temperature variations during a diurnal cycle were smallerinside the anomalous regions The locations of the anomalies wereshown to closely match the expected deposition profile of highenergy (~ MeV) electrons moving counter rotational to the moonssuggesting an energetic source to drive their formation Howeverthe mechanisms by which thermal conductivity enhancementoccur lack quantitative comparison with theoretical andexperimental results

1 1

1

1 22

2 2 1

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175

Electron interactions with the grains can excite molecules which ifnear enough to an intergrain contact can cause atoms or moleculesto migrate into the contact region thus increasing the contactvolume or sintering the grains Sintering improves the thermalcontact between grains leading to increased effective thermalconductivity of the regolith Equations previously developed todescribe material behavior in nuclear reactor were used to estimatethe timescale for the energetic electrons to increase the contactvolume sufficiently to describe the enhanced thermal conductivityof the anomalous regions In order to properly constrain thesintering calculations the unique electron energy distributionmeasured in the vicinity of each of the moons was used in thecalculations and molecular dynamics simulations of excitedelectrons in water ice were carried out to determine the length scalefor an average electron excitation or ionization event This lengthscale determines the distance from the primary reaction at whichelectrons can still be mobilized to move into the contact region Thesintering timescales were compared to published values formicrometeorite resurfacing rates in order to determine if electroninduced sintering can create a stable equilibrium on the surface ofthe moons

Author(s) Micah Schaible Robert E JohnsonInstitution(s) 1 University of Virginia

50805 ndash Coherent Backscattering Effect in Saturnianvs Uranian Satellites Effects on Band Depths andShapesIn this work we examine the changes in depth and shape ofindividual absorption bands as a function of solar phase angle thatare caused by the coherent backscattering effect (CBE) in near-IRspectra of saturnian and uranian satellites We have quantifiedband depths and shapes for real-world data (from Cassini Visual ampInfrared Mapping Spectrometer (VIMS) and TripleSpec at ApachePoint Observatory) and also modeled spectra of densely packed icyparticulate surfaces with the MSTM (multisphere T-matrix) version40 code specifically developed to model light scattering in regolithlayers MSTM4 allows us to calculate the brightness for thick fluffylayers on order of 20000 particles (compared to 1000 withprevious code versions) We have now obtained good matchesbetween model and real-world data at specific bands for severalhigher albedo moons We are finding that the normalized depth ofthe absorption band can increase or decrease with solar phaseangle depending on the albedo at the wavelength of normalizationthis is seen in all the data (VIMS ground-based and modelspectra) We model the change in the phase-angle-dependent banddepth in response to varying the size and packing of the constituenticy particles Indeed the coherent backscattering effect can beobserved at some wavelengths and entirely disappear at othersbecause CBE requires a specific range of size and packing (cfMuinonen et al 2014) we see this effect as wellThis work is supported by NASArsquos Outer Planets Research program(NNX12AM76G PI Pitman) Planetary Astronomy program(NNX09AD06G PI Verbiscer) and NASArsquos AdvancedSupercomputing Division Calibrated Cassini VIMS data cubesappear courtesy of the Cassini VIMS team and the PDS

Author(s) Karly M Pitman Ludmilla Kolokolova Anne JVerbiscer Charles Gulotta Emily C S Joseph Daniel WMackowski Bonnie J Buratti Thomas W MomaryInstitution(s) 1 Auburn University 2 Jet PropulsionLaboratory California Institute of Technology 3 PlanetaryScience Institute 4 Space Science Institute 5 University ofMaryland 6 University of Virginia

50806 ndash Charging and Discharging of AmorphousSolid Water Ice Effects of PorosityIntroduction Amorphous solid water (ASW) is abundant onSaturnrsquos icy satellites and rings [12] where it is subject tobombardment of energetic ions electrons and photons togetherwith secondary electron and ion emission this may leave thesurfaces charged Surface potential can affect the flux of incomingcharged particles altering surface evolution We examined the roleof porosity [3] on electrostatic charging and discharging of ASW

films at 30ndash140 KExperiment Experiments were performed in ultra-high vacuum[4] ASW films were deposited at 30 K onto a liquid-He-cooledquartz crystal microbalance (QCM) Film porosity was calculatedfrom the areal mass via the QCM and thickness via a UV-visibleinterferometry ASW films were charged at 30 K using 500 eV He Surface potentials (V ) of the films were measured with a Kelvinprobe and infrared spectra were collected using a Fouriertransform infrared spectrometerResults We measured V of the ASW film at 30 K as a function ofion fluence (F) The V (F) deviates from a straight line at lowfluence attributed to emitted secondary electrons due to thenegative polarization voltage [56] and increases linearly when theV is positive We also measured V as a function of annealingtemperature We prepared ASW films with various porosities byannealing the films to different temperatures (T ) prior toirradiation or varying the vapor-beam incidence angle (θ) Uponheating we observed sharp decreases of the V at temperaturesthat strongly depend on T and θ Decreases of the infraredabsorbance of the dangling OH bands of the charged film sharesimilar trends as that of the V We propose a model that includesporosity for electrostatic chargingdischarging of ASW films attemperatures below 100 K Results are applicable to the study ofplasma-surface interactions of icy satellites and ringsReferences [1] Jurac et al J Geophys Res 100 14821 (1995)[2] A L Graps et al Space Sci Rev 137 435 (2008) [3] U Rautet al J Chem Phys 127 204713 (2007) [4] C Bu and R BBaragiola J Chem Phys 143 074702 (2015) [5] C Bu et al JChem Phys 142 134702 (2015) [6] M J Iedema et al J PhysChem B 102 9203 (1998)

Author(s) Caixia Bu Raul A BaragiolaInstitution(s) 1 University Of Virginia

50807D ndash Porosity effects on crystallization kineticsof Amorphous Solid Water Implications for cold icyobjects in the Outer Solar SystemCrystalline ice has been identified on the cold surfaces of most icysatellites and TNOs [1] This is surprising since accretion of watervapor at temperatures (T lt 100 K) should result in the amorphousphase [2] There are several possible explanations for theunexpected presence of crystalline ice on cold bodies includingcryovolcanism [3] and pulsed heating by micrometeoritic impacts[4]A salient feature of ice films condensed at low T is microporosityknown to increase with deposition angle [5] Here we investigatethe dependence of the crystallization rate on the ice porosity whichcould contribute to the observed variation in crystallization time τreported in the literature [2] Such dependence is noted in otherporous materials such as zeolites and titania [6 7]Amorphous ice films were deposited on a CsI substrate from acollimated water vapor source at 10 K at incidences varying from 0to 70deg as well as from an omnidirectional water vapor source Thefilms were heated to temperatures between 130 and 140 Kfollowing deposition The isothermal transition from amorphous tofully crystalline phase was characterized by analyzing thetime-dependent evolution of the OH-stretch absorption band usingtransmission infrared spectroscopy Our initial results show that τdecreases with increasing porosity for instance a film deposited at45deg was observed to crystallize ~6 times faster than a film depositedat 0deg The preliminary estimate of the porosity of the 45deg film is~50 higher than that of the film deposited at normal incidenceOur findings can explain the reported variation in temperature-dependent τ [2] and contribute to the understanding of crystallineice on cold bodies in the Outer Solar System1 Mastrapa RME et al In Gudipati MS amp Castillo-Rogez JEds The Science of Solar System Ices Springer New York 20132 Baragiola RA In Devlin amp Buch Eds Water in ConfiningGeometries Springer-Verlag 20033 Jewitt DC amp Luu J Nature 432 731 20044 Porter SB et al Icarus 208 492 20105 Stevenson KP et al Science 283 1505 19996 Francis RJ amp OrsquoHare D J Chem Soc Dalton Trans 31331998

1 1

4 56 5 3

1 2 2

+

s

ss

s s

a

sa

s

1 1

c

c

c

176

7 Kirsch BL et al J Phys Chem B 108 12698 2004

Author(s) Emily H Mitchell Ujjwal Raut Raul ABaragiolaInstitution(s) 1 University of Virginia

50808 ndash Identifying new surface constituents of icymoons using mid-infrared spectroscopySpectroscopic compositional studies of the icy satellites can help usto better understand the formation and evolution of material in theouter solar system The spectral complexity of the Saturniansatellite system as seen in reflected visible light suggests additionalcomplexity may be present at mid-infrared wavelengths from whichunique compositional information can be gleaned [1] In additionthe mid-infrared is the region of the stronger fundamentaldiagnostic vibrational modes of many compounds HoweverCassini Composite Infrared Spectrometer (CIRS) surfacecompositional studies have received little attention to dateWe are exploring the suitability of mid-infrared spectroscopy fordiscovering non-H O compounds on icy moon surfaces On thedark terrain of Iapetus we find an emissivity feature at ~855 cmand a potential doublet at 660 and 690 cm that do not correspondto any known instrument artifacts [2] We attribute the 855 cmfeature to fine-grained silicates similar to those found in dust onMars and in meteorites which are nearly featureless at shorterwavelengths [3] Although silicates on the dark terrains of Saturnrsquosicy moons have been suspected for decades there have been nodefinitive prior detections Serpentines measured at ambientconditions have features near 855 cm and 660 cm [4]However peaks can shift depending on temperature pressure andgrain size so measurements at Iapetus-like conditions arenecessary for more positive identifications [eg 5]We measured the vacuum low temperature (125 K) spectra ofvarious fine-grained powdered silicates We find that some of thesematerials do have emissivity features near 855 cm and match thedoublet Identifying a specific silicate would provide clues into thesources and sinks of the dark material in the Saturnian system Wereport on our ongoing exploration of the CIRS icy moon datasetand plans for future measurements in JPLrsquos Icy Worlds SimulationLab[1] Flasar FM et al (2004) Space Sci Rev 115 169[2] Young CL et al (in review) ApJ Lett[3] Christensen PR et al (2004) Sci 306 1733[4] Bishop JL et al (2008) Clay Minerals 43 35[5] Wray JJ et al (2014) DPS 46th Meeting Vol 46

Author(s) Cindy L Young James J Wray Kevin P Hand Michael J Poston Robert W Carlson Roger N Clark John RSpencer Donald E JenningsInstitution(s) 1 California Institute of Technology 2 GeorgiaInstitute of Technology 3 Jet Propulsion Laboratory 4 NASAGoddard Space Flight Center 5 Planetary Science Institute 6Southwest Research Institute

50809 ndash Composition and evolution of Tritons icysurface between 2002-2014 from SpeXIRTFWe observed Triton in the near-infrared (07-25 μm) over 63nights using the SpeX instrument at NASAs Infrared TelescopeFacility (IRTF) between 2002 and 2014 Tritonrsquos spectrum hasabsorption features due to N CO CH CO and H O in thiswavelength range We calculated the equivalent width (or fractionalband depth for H O) of select absorption bands in each of the 63night-averaged spectra Longitudinal distributions for the volatileices (N CO CH ) show large rotational amplitude while thenon-volatile ices (CO H O) show little amplitude over one Tritonrotation Absorption from N and CH increased over the period ofthe observations whereas absorption from the non-volatile icesremained constant The sub-solar latitude on Triton is currently at-42 degrees south so some areas of Triton are visible for a fullrotation Combined with our findings this suggests that thesouthern latitudes are dominated by non-volatile ices with largerconcentrations of volatile ices found in the observable region northof the equator Changing viewing geometry over the period of the

observations explains the increase in volatile absorption As thesub-solar point moves northwards more of the volatile-richnorthern regions are coming directly into view Geological evidencefrom Voyager 2 pointed to a southern hemisphere dominated byvolatile ices significant changes have occurred over the interveningquarter century

Author(s) Bryan J Holler Leslie A Young William MGrundy Cathy B OlkinInstitution(s) 1 LASP 2 Lowell Observatory 3 SouthwestResearch Institute

50810 ndash The Surprisingly Short Rotation Period ofHiiaka Haumeas Largest SatelliteThe dwarf planet Haumea stands out from the rest of its KuiperBelt counterparts with its rapid rotation two satellites andassociated collisional family of small objects The larger outersatellite Hiiaka orbits Haumea with a period of 49462 days aneccentricity of 005 and an inclination of ~2 degrees If it formedlike a regular satellite and tidally evolved to its current location itwould be expected that Hiiaka would be tidally despun HoweverHST and Magellan ground based data show that Hiiaka shows a20 peak-to-peak brightness variability from which we havedetermined that Hirsquoiakarsquos rotation period is ~98 hours (double-peaked) The spin period is ~120 times faster than its orbital periodand too fast to be caused by standard mechanisms (eg spin-orbitresonance or chaos) The unusual spin rate also suggests thatHirsquoiaka could be the only known regular satellite to have asignificant free obliquity (as opposed to forced obliquity) Thisobliquity would result in stable spin axis precession We haveinvestigated the observability of Hiiakas spin precession bydetermining how the angle between the Earth line of sight and thespin axis direction changes over a precession cycle for variousobliquities If the obliquity is significant the resulting light curveevolution would be detectable within a ~decade We will presentthese results and discuss their implications for the formation ofHiiaka and Haumea

Author(s) Danielle M Hastings Darin Ragozzine Daniel CFabrycky Luke D Burkhart Michael E Brown Cesar Fuentes Matthew J HolmanInstitution(s) 1 California Institute of Technology 2 FloridaInstitute of Technology 3 Harvard University 4 Harvard-Smithsonian Center for Astrophysics 5 Universidad de Chile 6University of Chicago

50811 ndash Orbital analysis of the inner Uraniansatellites from Hubble imagesThe thirteen inner moons of Uranus form a densely-packed andpossibly chaotic system Numerical simulations show that severalgroups of moons exhibit complex resonant interactions and Mabshows as-yet unexplained variations in its orbit However themasses of these moons are currently unknown limiting theinsights that can be gained from numerical simulations Using over650 long-exposure images taken during 2003-2013 by the HubbleSpace Telescope through broadband filters we have obtainedastrometry for eleven of Uranusrsquos inner moons comprising thePortia group (Bianca to Perdita) plus Puck and Mab attempts tomeasure the positions of Cordelia and Ophelia are on-going Usingthese measurements which are frequently accurate to 005 pixelsor less we have derived Keplerian orbital elements including theinfluence of Uranusrsquos oblateness The elements show year-to-yearvariations that are statistically significant and indicate the role ofmutual perturbations among the moons We are also using thisinformation to place new constraints on the masses of thesemoons We will present our most recent findings

Author(s) Robert S French Mark R Showalter Imke dePater Jack J LissauerInstitution(s) 1 NASA ARC 2 SETI Institute 3 University ofCalifornia Berkeley

1 11

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Authors IndexAbell Paul 31206Acton Charles Hall 31205Adamkovics Mate 20505Adams Elisabeth R 50102Ahlers Johnathon 41705Akeson Rachel L 41701Albers Nicole 21807Albin Edward F 21919Alcock Charles 31207Ali-Dib Mohamad 50708Altwegg Kathrin 50301Anderson Carrie 30001Angelo Isabel 41703Arevalo Ricardo 31211Armstrong Eleanor Sophie31130Arney Giada 40402Auger Anne-Theacuteregravese 50003Aye Klaus-Michael 42001Backman Dana E 31217Badhan Mahmuda A 41617Bagenal Fran 10006Bailey Jeremy 41616Baines KH 40005Banfield Don 40108Banks Maria E 21506Bannister Michele T 20304Barclay Thomas 50706Bardyn Anais 50308Barentsen Geert 30821Barnes Jason W 41805Barnouin Olivier S 40209Barth Erika L 30002Battalio Joseph 40105Batygin Konstantin 30708Bauer James M 41501Becker Tracy M 10403DBell James F 31208Bell Jared M 41921Bellotti Amadeo 40304Benecchi Susan D 2110321906Benner Lance A M 20407Beacuterard Diane 10402Bering Edgar Andrew 2191231210Bertrand Tanguy 21020Beyer Ross A 10206Bhattacharyya Dolon 41902Bierhaus Edward B 50801Binzel Richard P 30103Bjoraker Gordon 40306Blacksberg Jordana 30908Blalock John J 31108Bland Michael T 10307Blaney Diana L 42003Blum Juumlrgen 30201Blumenthal Sarah 50403Bodewits Dennis 50303Bonev Boncho P 50606Booth Shawn 41523Bosh A S 10503Bosh Amanda S 21031Bottke William 20107Bougher Stephen W 50505Bourzutschky Alexander40405Bowman M Oliver 30820Bradley Eric Todd 21503Brasil Pedro Ivo de Oliveira21401Brasunas John C 31216Brauer Kaley 21303

Brown Adrian J 21310Brown Linda R 31134Brown Michael E 21315Brown Peter G 40207Brown Zarah 21805Brozovic Marina 40206Brucker Melissa J 30707Bu Caixia 50806Buczkowski Debra 21204Buie Marc W 20003Bullock Mark A 21708Buratti Bonnie J 20004Burger Matthew H 21502Busch Michael W 40205Butler Bryan J 21004Buxner Sanlyn 21907Buxner Sanlyn R 21915Campins Humberto 10605Canup Robin M 30207Cao Hao 40301Capanna Claire 41311Carruba Valerio 20106Cartwright Richard J 41102Chaffin Michael S 50508Challener Ryan C 41605Chambers John E 41801Chan Kwing Lam 31129Chancia Robert O 21812Chang Chan-Kao 30711Chanover Nancy J 31202Charnay Benjamin 41615Charnoz Sebastien 30206Chatelain Joseph 30703Cheng Andrew F 10502Chesley Steven R 30809Chi Peter J 21709Chodas Paul 21409Chrenko Ondrej 41802Christensen Eric J 30819Christou Apostolos 10702Cibulkova Helena 30710Clancy R T 40107Clark Roger Nelson 40401Clarke John T 50507Cobb Whitney 21909Cochran William D 41702Colwell Joshua E 10410Combi Michael R 41314Cook Jason C 20002Cooper John F 10411Cordiner Martin 20503Corlies Paul 30007Corliss Jason B 41524Cosentino Rick 31120Cottini Valeria 31009Cotto-Figueroa Desireeacute21320Courtin Reacutegis 31010Coustenis Athena 31008Crismani Matteo MichaelJames 41918Crowell Jenna L 21304Cruikshank Dale P 10102Cuk Matija 30901Cull-Hearth Selby 42002Curry Shannon 50506DAngelo Gennaro 41806Dalba Paul A 50401Dalle Ore Cristina M 21027Dalton Heather 21920Davidsson Bjorn 41315Davies Ashley Gerard 40503Davighi Joseph E 40302

Dawson Rebekah Ilene30601 41704Day Brian 21602de Kleer Katherine R 40504de Leon Julia 10609de Pater Imke 40906Debes John H 41619Deckers Johannes 30202DDeighan Justin 50509Del Rio Gaztelurrutia Teresa31112DeLarme Emerson 41602Delitsky M L 21702Dello Russo Neil 41512DeMeo Francesca E 30108Denevi Brett W 20801Denk Tilmann 41202Desch Steven 21028DeVogel Kayla 31124Dhingra Deepak 41103Dhingra Rajani D 30008Dias-Oliveira Alex 20009DDiSanti Michael A 41510Dombard Andrew J 21208Domingue Deborah L 21312Dones Henry C (Luke)41520Dong Chuanfei 41913Drube Line 10604Drummond Jack D 21404Dukes Catherine 21508Dumas Christophe 31219Durda Daniel D 20202Earle Alissa M 20005Edgington Scott G 31125El Moutamid Maryame10405Elliott Joshua Peter 21813Elrod Meredith K 41914Ennico Kimberly 20008Erwin Justin 21017Espley Jared R 50504Esposito Larry W 10409Estrada Paul R 50702Faggi Sara 50604Fan Siteng 20509Farnham Tony L 41504Farnocchia Davide 41503Feaga Lori M 50306Feldman Paul D 50305Fernandez Yanga R 41507Filacchione Gianrico 50008Fischer Patrick D 40905Flasar F Michael 50207Fletcher Leigh N 50203Folonier Hugo Alberto 31017Forget Francois 10512Fornasier Sonia 50006Foster Andrew S 41606Fougere Nicolas 41306Frantseva Kateryna 21402Fraser Wesley Cristopher21115French Linda M 30705French Robert S 50811Friedson Andrew James31121Frouard Julien 30712Fry Patrick M 31101Fuentes Cesar 31212Gabriel Travis SJ 30904Gaertner Sabrina 30203Galanti Eli 40308

Gao Peter 50404DGarcia-Melendo Enrique40006Garland Justin 41604Garland Ryan 41601Gerakines Perry A 21030Giles Rohini Sara 40309Gladman Brett 50710Gladstone G R 10005Goguen Jay D 41105Goldspiel Jules M 40102Gordon Mitchell K 21804Gorius Nicolas 41001Gosmeyer Catherine 41613Granahan James C 21301Granvik Mikael 21407Grauer Albert D 21917Grav Tommy 30811Grava Cesare 10712Gray Candace L 20101DGreenberg Adam 30704Greenstreet Sarah 30812Greybush Steven J 41923Grier Jennifer A 21908Griffith Caitlin Ann 31016Gronoff Guillaume 41924Groussin Olivier 50005Grundy William M 1000420001Guerlet Sandrine 31117Guettler Carsten 41301Guimaratildees Ana HelenaFernandes 50106Gurwell Mark 10506Hadnott Bryne 30009Hahn Matthias 21029Hamilton Douglas P 20007Hammel Heidi B 31102Hammergren Mark 21314Hand Kevin P 40506Hansen Alexander K 21809Hansen Candice 41104Hanus Josef 30701Hardersen Paul S 10601Harrington Joseph 50406Hart Richard A 21701Hartig Kara 21014Hartwick Victoria 40104Hartzell Christine 20405Hastings Danielle M 50810Hayne Paul O 10309Hebrard Eric 41607Helled Ravit 31110Hendrix Amanda R 10306Hesman Brigette E 31116Hewagama Tilak 21706Hibbitts Charles A 21505Hill Matthew Eric 21026Hines Dean C 41313Hinkle Mary L 30104Hinson David P 10501Hirabayashi Masatoshi40204Hoette Vivian L 21921Hofstadter Mark D 41304Holler Bryan J 50809Hollingsworth Jeffery L41905Holman Matthew J 21112Hora Joseph L 31221Howe Alex 41614Howell Ellen S 21311Howell Robert R 40901

178

Howett Carly Jacqueline Amy10205Hsieh Henry H 41402Hu Renyu 40409Hudson Reggie L 21107Hue Vincent 31115Hueso Ricardo 40002Hui Man-To 41518Hurford Terry 20109Hurley Dana 41006Hutcherson Adam 21509Hyodo Ryuki 21810Imanaka Hiroshi 41618Irwin Patrick Gerard Joseph40001Jackson Brian K 50108Jacobson Robert A 10208Jakosky Bruce M 30501Jakubik Marian 21319Jedicke Robert 31225Jehin Emmanuel 41312Jennings Donald E 30005Johnson Robert E 31002Johnson Torrence V 40403Jones Lynne 31222Jorda Laurent 41309Jost Bernhard 41302Kahre Melinda A 41906Kaib Nathan A 41803Kalyaan Anusha 50707Kammer Joshua A 10204Karkoschka Erich 31003Kaspi Yohai 40408Kataria Tiffany 50407Kavelaars J J 21114Kawakita Hideyo 41515Keane James Tuttle 30709Keller Horst Uwe 50009Keller John W 21507Kelley Michael S 50607Khayat Alain 41912Killen Rosemary M 21501Kim Sang J 31114Kinser Rebeca 31001Kitazato Kohei 30713Klassen David R 2191441908Klaus Kurt K 31223Klima Rachel L 21318Knight Matthew M 50611Kohout Tomas 21213Kollmann Peter 10510Komacek Thaddeus D21902 50408Kopparla Pushkar 41611Kortenkamp Stephen J20204 30902Korycansky D G 30907Koskinen Tommi 21016Kostiuk Theodor 50202Koutroumpa Dimitra 10703Kramer Emily A 50609Kutepov Alexander 31011Lambrechts Michiel 50703DLamy Philippe L 41303Landsman Zoe A 10610Lanzano Alexander 31006Larsen Jeffrey A 30814Larson Erik J 31005Lavvas Panayotis 20508Le Beau Raymond P 31105Le Gall Alice 21007Le Maistre Sebastien 42006Lederer Susan M 41502Lee Greg 31013

Lee Seungwon 50302Lee Yuni 50503Lehner Matthew J 21116Leith Thomas 10603Lejoly Cassandra 20302Lellouch Emmanuel 10507Lemmon Mark T 40109Levasseur-Regourd A 41310Levison Harold F 30204Lewis Benjamin 2191141517Lewis Mark C 21808Leyrat Cedric 41305Li Cheng 31107Li Daohai 41201Li Jian-Yang 10304Liang Mao-Chang 21023Lightholder Jack 31226Ligier Nicolas 40507Lilly (Schunova) Eva 21406Limaye Sanjay 21704Lin Hsing-Wen 21117Linscott Ivan 10103Lisse Carey M 21005Lister Tim 30816Livengood Timothy A 41911Loeffler Mark J 50206Lora Juan M 30004Lorenz Ralph 41925Lorenzi Vania 21008Lovell Amy J 41514Lucas Michael P 21316Luhmann Janet 50502Luiz Andre Amarante10211DLustig-Yaeger Jacob 41610Luszcz-Cook Statia H 31103Lyons James 50709MacDonald Mariah G 50105Macke Robert J 20403MacKenzie Shannon 31224MacLennan Eric M 21305Mai Chuhong 41612Mainzer Amy K 30801Makarov Valeri 10706Malina Ondrej 21313Mankovich Christopher31127Marchant Jon 41316Marchi Simone 10303Marchis Franck 50101Margot Jean-Luc 50103Marshall Sean E 20409Marsset Michael 10611Martone Alexis 21707Marzari Francesco 41709Matcheva Katia 31132Matson Dennis L 41003Mayo Louis 21916McAdam Margaret 10608McCord Thomas B 21211McDonald George D 31012McFadden Lucy-Ann A21209McGouldrick Kevin 20102McGrath Melissa 40904McKay Adam 50603McKinnon William B 10106McNutt Ralph L 10509Meech Karen Jean 50704Meinke Bonnie K 20209Mellton Chad 21104Meyer Michael 40101Michaels Timothy I 21022Migliorini Alessandra 50304

Milam Stefanie N 50605Milbury Colleen 10709Mitchell Emily H 50807DMolter Edward M 31015Momary Thomas W 31119Mommert Michael 30804Montmessin Franck 41917Moore Casey A 41907Moore Jeffrey M 1000310203Moores John 10710Moorhead Althea V 30818Morate David 21321Moretto Mark J 50608Morgan Thomas H 31203Morishima Ryuji 30906Morooka Michiko W 41922Moses Julianne I 50405Moskovitz Nicholas 30810Moullet Arielle 31131Mousis Olivier 30910Mueller Beatrice E A 50610Mueller Michael 20401Mumma Michael J 41909Muntildeoz-Gutieacuterrez MarcoAntonio 50104DMusacchio Fabrizio 40501DMusiolik Grzegorz 30909Naidu Shantanu P 20408Nance Elizabeth 31104Nault Kristie A 30815Nayak Michael 20108Neish Catherine 10708Nelson Robert M 40502Nesvold Erika 41707Nesvorny David 20308Neveu Marc 10310DNixon Conor A 31014Noll Keith S 21101Novak Robert E 41910Nugent Carolyn 30101Nugent Carolyn R 21905ONeill Morgan E 40307Ohtsuki Keiji 21410Oklay Nilda 50007Olkin Catherine B 10101Opitom Cyrielle 50602DOrton Glenn S 50204Otarola Angel 31218Paddack Stephen 40201Paetzold Martin 50001Paganini Lucas 41511Pajuelo Myriam Virginia20105Palmer Eric 21317Parisi Marzia 50209DPark Ryan 21210Parker Alex Harrison 20309Parkinson Christopher D31122Pasachoff Jay M 1070721012Patterson Gerald Wesley31209Payne Matthew John 21113Peacock Sarah 40406Pendleton Yvonne J 21601Penteado Paulo F 21106Penttilauml Antti 21307Perera Viranga 2020620404Perez-Hoyos Santiago 31123Perry Mark E 41004Person Michael J 10505Philippe Sylvain 21019

Piccialli Arianna 20103Pieters Carle M 10302Pike Rosemary E 20306DPilorget Cedric 40103Pitman Karly M 50805Podolak Morris 31106Polidan Ronald S 21703Polishook David 40202Porter Simon B 10210Portyankina Ganna 41005Poston Michael 30209Poulet Francois 50004Prem Parvathy 10711Prettyman Thomas H 21309Prialnik Dina 41106Protopapa Silvia 41508Quillen Alice C 50802Radebaugh Jani 21901Rafkin Scot CR 30003Rall Jonathan 21924Ramanjooloo Yudish50601DRannou Pascal 31004Raponi Andrea 21202Rathbun Julie A 3120140505Raugh Anne C 31204Rauscher Emily 40801Raymond Carol A 10301Rehnberg Morgan 1040420205Resnick Aaron C 21015Retherford Kurt D 10508Richardson Derek C 21806Richardson James E 30808Richey Christina 40601Ries Judit Gyorgyey 21904Rimlinger Thomas 41804Rivkin Andrew S 10607Roberts James H 21207Roberts-Pierel J D 31128Rodriguez-Ford Linda A20207Roe Henry G 21018Roig Fernando Virgilio21405Rosenblatt Pascal 30208Roth Nathan 41509Rousselot Philippe 21102Ruesch Ottaviano 10311DRuprecht Jessica D 30802Russell April 21923Russell Christopher T20901 50201Ryan Eileen V 20203Ryan Erin L 30106Ryan William 30806Saito Hiroaki 30903Salmon Julien 10408Samarasinha Nalin H 41505Sanchez Juan Andres 21302Saacutenchez Paul 40208Sanchez-Lavega Agustin40003Sandor Brad J 20104Sarid Gal 30706Sayanagi Kunio M 31118Schaefer Laura 41609Schaible Micah 50804Schambeau Charles Alfred41522Schenk Paul M 20006Schinder Paul J 31007Schloerb F Peter 50002Schmidt Britney E 10308

179

Schneider Nicholas M 41916Schools Joe 42005Schroumlder Stefan 10305Schulz Rita 30911Schwamb Megan E 21109Schwieterman Edward20208 40404Sciamma-OBrien Ella 20507Scipioni Francesca 50803Scully Jennifer E C 21203Serigano Joseph 20504Sharkey Benjamin N L30807Sheets Holly A 40407Sheppard Scott S 20307Shinnaka Yoshiharu 41516Shou Yinsi 41519Showalter Mark R 10209Shupla Christine 21910Sicardy Bruno 10401Sickafoose Amanda A 10504Sidrow Evan 21025Sie Zong-Fu 21110Simmons Gary G 41101Simon Amy A 50205Sinclair James 31113Singer Kelsi N 10202Siu Ho Chit 40203Sizemore Hanna G 21205Skrutskie Michael F 40902Smith Howard T 21033Smith Mary-Ann H 41920Smith Robert J 21034Soderlund Krista M 40508Solin Otto 21408Solomonidou Anezina 30006Sonnett Sarah M 30105Spalding Christopher 50107Spencer John R 10105

Spiga Aymeric 31111Spilker Linda J 21801Spitale Joseph N 41002Springmann Alessondra41404Squire Jared 31213Sromovsky Lawrence A40004Stamper Nicholas C 21306Stansberry John A 21032Stark Glenn 31133Steckloff Jordan 41506Steffl Andrew J 41308Stern SA 10001Stevens Michael H 41915Stevenson David J 40303Stewart Glen R 21811Stickle Angela M 31214Stofan Ellen R 20201Summers Michael E 10511Sung Keeyoon 31018Sunshine Jessica 21212Svedhem Haringkan 41919Sykes Mark V 21206Sylvestre Melody 40008DTabeshian Maryam 41708Tabor-Morris Anne 21918Takahashi Yasuto 40007DTakir Driss 10602Tamayo Daniel 41204Teanby Nicholas A 20502Tegler Stephen C 21105Teiser Jens 42004Tejfel Victor G 31109Tellmann Silvia 41903Tenishev Valeriy 50309Thelen Alexander E 31126Thirouin Audrey 20301Tholen David J 41403

Thomas Cristina A 30813Throop Henry B 2100921035 21925Tinetti Giovanna 41620Tiscareno Matthew S 10407Titus Timothy N 20402Tokunaga Alan T 31220Tozzi Gian-Paolo 50307Trafton Laurence M 21002Trainer Melissa G 2050621913Traub Wesley A 50711Trilling David E 30102Trimble Christie J 10406Trowbridge Alexander J10201DTrujillo Chadwick A 21111Tsang Constantine 21705Turner Neal J 21803Turrini Diego 50705Umurhan O M 21011Urata Richard Atsuki 40106Van Laerhoven Christa L41706Verbiscer Anne J 21003Veres Peter 30803Verma Ashok Kumar 10705Vernazza Pierre 10612Vervack Jr Ronald J 10701Videen Gorden 41513Vilas Faith 10704Villanueva Geronimo Luis20701 50501Villarreal Michaela 21201Vinatier Sandrine 20501Vincent Jean-Baptiste 41307Virkki Anne 20406DVodniza Alberto Quijano30805

Volk Kathryn 20305Vrastil Jan 21403Wainscoat Richard J 30107Wakeford Hannah 50402DWalsh Kevin J 30205Wang Huiqun 41904Warner Brian D 30702Weaver Harold A 1000210207Weissman Paul R 3090540701Weryk Robert J 41525West Robert A 50208White Oliver 21006Whizin Akbar 50701DWiegert Paul 41521Wigton Nathanael 10606Williamson Hayley N 41901Wong Ian 20303Wong Michael H 40305Wong Michael L 21021Woodson Adam 41926Yanamandra-Fisher Padma A21903 31135Yang Bin 30109Ye Quan-Zhi 30817Young Cindy L 50808Young Eliot F 21010Young Leslie 10104Yu Tze Yeung Mathew 21108Yung Yuk 30401Zalucha Angela M 21024Zangari Amanda M 21001Zhang Xi 41608Zhang Zhimeng 21802Ziffer Julie 21922Zou Xiaoduan 21308Zuluaga Carlos A 21013

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