PerformanceandChallengesforHabEx(andLUVOIR)ExploringOtherPlanetarySystemsandEnablingaBroadRangeof

GeneralAstrophysics&SolarSystemScience

BertrandMennessonJetPropulsionLaboratory,CaliforniaInsFtuteofTechnology

andtheHabExStudyTeam©2018CaliforniaIns1tuteofTechnology,governmentsponsorshipacknowledged Imagecredit:MarkGarlick,space-art.co.uk

1KISSMeeFng,PasadenaApril112018

HabExTopLevelScienceGoals

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HabExataglance(ArchitectureA)

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•  Off-axisf/2.5monolithicprimary•  CoronagraphInstrument(0.45-1.8µm)

o  R=140inthevisible,R=40intheNIRo  IWA=62masat0.5µm

•  StarshadeInstrument(0.2–1.8µm)o  R=140inthevisible,R=40inNIR,R=7inUVo  IWA=60masover0.3to1.0µmo  Slewtodifferentdistancestocover<0.3or>1µm

HabExHybridDesignandObservingStrategy

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HabExcombinesthestrengthsoftwohighlycomplementarystarlightsuppressionsystems:

InternalCORONAGRAPH ExternalSTARSHADE

•  Verynimble•  Searchesforplanetsaroundmanystars•  Takesimagesatmul1plevisitstomeasureorbits

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•  Very“photon”efficient•  Accessescloser-inplanetsatagivenλ•  Takesbroadspectraofallplanetsfoundin~50-100mostinteres1ngsystems

HabExExoplanetSurveyStrategy

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BroadSurvey(3.5yeartotal)•  Roughly110stars•  Roughly6observa1onsofeach•  50%completenessforexo-Earths•  Spectraofmostinteres1ngsystems

(andallthosewithEECs)o  0.3-1.0μmatoncewithstarshadeo  R=7(grism)0.3-0.45μmo  R=140(IFS)0.45-1.0μm

DeepSurvey(0.25year)•  Roughly10high-priorityclose-by

(<6pc)GKdwarfs•  Deepbroadbandimagetothe

systema1cfloor•  Spectra

DetecFngandCharacterizingPotenFallyHabitableWorlds

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•  HabExwillsurvey~110nearbysunlikestarswiththecoronagraphtosearchforpoten1allyhabitableworldsanddeterminetheirorbits

Credit:GarrethRuane(Caltech) Credit:SergiHildebrandt(JPL)

•  Mostinteres1ngsystemswillbestudiedfurtherwiththestarshade(broad-band12”x12”imageandspectraofindividualplanets)

D = 4 m

Exo-Earth near UV to near IR Spectra

Atmosphere?

Life?

Habitability?

Credit:TylerRobinson

Family Portraits of our Neighboring Planetary Systems

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•  Spectraover0.3-1.0μmatoncewithstarshadeforplanetswithin1.5”•  R=7(grism)0.3-0.45μm•  R=140(IFS)0.45-1.0μm

•  NearUVand/ornearUVspectraforselectsystems

Credit:TylerRobinson(NAU)

&SergiHildebrandt(JPL)

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Yields of Characterized Planets (Chris Stark, STScI)

ExpectedHabExYields*Detectandcharacterizetheorbitsandatmospheresof:•  Rockyplanets:

•  92rockyplanets(0.5-1.75RE)•  Includes12EarthAnalogs(0.5-1.4RE)

•  SubNeptunes:•  116sub-Neptunes(1.75-3.5RE)

•  GasGiants•  62gasgiants(3.5-14.3RE)

*AssumesSAG13NominalOccurrenceRates.

Yields of Characterized Planets

Credit:TiffanyMeshkat(IPAC)

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Thisalllooksgreatbut…

•  WhatassumpFonswentintothis?•  Aretheyreasonable?

•  ScienceyieldsensiFvitytouncertaintyonastroparametersandinstrumentalperformanceassumpFons?

!HabEx(andLUVOIR)Challenges

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Astronomical Parameter AssumpJons

Parameter Value Descrip1on η⊕ 0.24 FracFonofSun-likestarswithanexo-Earthcandidate Rp [0.6,1.4]R⊕ Planetradiusa α [0.95,1.67]AU Semi-majoraxisb e 0 Eccentricity(circularorbits)

Cosi [–1,1] Cosineofinclina1on(uniformdistribu1on) ω [0,2π] Argumentofpericenter(uniformdistribu1on) M [0,2π] Meananomaly(uniformdistribu1on) Φ Lamber1an Phasefunc1on AG 0.2 Geometricalbedoofplanetfrom0.55–1µm zc 23magarcsec-2 AverageVbandsurfacebrightnessofzodiacallightforcoronagraph

observa1onsc zs 22magarcsec-2 AverageVbandsurfacebrightnessofzodiacallightforstarshadeobserva1onsc x 22magarcsec-2 Vbandsurfacebrightnessof1zodiofexozodiacaldustd n 3 Numberofzodisforallstars

YieldesFmatesassumezeropriorknowledgeofplanetsaroundtargetsstars

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SensiJvity to Astronomical Parameters: ηEarth and exozodi level (C. Stark)

0 10 20 30 40Median Exozodi Brightness (zodis)

0.1

0.2

0.3

0.4

0.5

ηEa

rth

0 10 20 30Yield of exoEarth Candidates

0 10 20 30Yield of exoEarth Candidates

2.0 2.5 3.0 3.5 4.0 4.5 5.0D (m)

0.1

1.0

10.0

Prob

abili

ty o

f zer

o ex

oEar

th c

andi

date

s (%

)

eta=0.08

eta=0.24

eta=0.70

CurrentLBTIData

Moreworkneededin2018tofullyexplorethesensiRvityofHabExscienceyieldtomaininstrumentalandastroparameters(similartoStarketal.2014&2015),andtoprecursorobservaRonsoftargetsystems.

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Instrument Performance AssumpJons: Coronagraph

Parameter Value Descrip1on

ζ <=10-10 Rawcontrasta

Δmagfloor 26 SystemaFcnoisefloor(faintestdetectablepointsource)

Τcore 0.48 Coronagraphiccorethroughputa

Τ 0.18 End-to-endfacilitythroughput,excludingcorethroughput

IWA 2.4λ/D Innerworkingangleb

OWA 32λ/D Outerworkingangle

Δλ 20% Bandwidth

aMaximumvaluebetweentheIWAandOWA.AssumesdualPZNoperaFonbSepara1onatwhichcorethroughputreacheshalfthemaximumvalue.

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Instrumental Parameter AssumpJons: Near UV - Visible Detector

Parameter Value Descrip1on

ξ 3×10-5countspix-1sec-1 Darkcurrent

RN 0countspix-1read-1 Readnoise(N/A)

τread 1,000s ReadFme

CIC 1.3×10-3countspix-1clock-1 Clockinducedcharge

Npix 2048 x 2048 (SS IFS) Array size

FornearIRspectralcharacteriza1on,requirementsare<~10-3count/pix/sandRN<1e-ofRN:-CustomHxRG?-1024x1024SAPHIRAdetector?

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HabEx Coronagraph Challenges •  Rawcontrastof~10-10orbe{erat2to3λ/DIWA,with:

o  InstantaneousBWof20%.o  High“core”throughput.

•  Post-processingfactorof20

o  Requiredtoreach4x10-11detec1onlimit,i.e.dmag=26.0•  Exquisite(LO)WFS&C:limitWFfluctua1onsandsensi1vitytothem

•  LargestableDMsandelectronicdrivers:

o  atleast64x64for1”OWAat0.6µmwitha4mo  256x256for15mLUVOIR(?)

•  Dualpolariza1onopera1onstronglypreferred:

o  Higherthroughput;EnablesPDIo  Planetreflectedlightpolarimetricstudies(e.gtalkbyT.Meshkat),oceanspecularreflec1ono  Affectstelescopedesign(f#=2.5)

•  HighContrastObserva1onsofBinaries•  LUVOIR15mon-axisdeployabletelescopeshallmeetalloftheabove,forasegmentedprimarywith

centralobscuraRon(acRveresearcharea)

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HabEx Coronagraph Challenges •  Rawcontrastof~10-10orbeserat2to3λ/DIWA,with:

o  InstantaneousBWof20%.o  High“core”throughput.

•  Post-processingfactorof20

o  Requiredtoreach4x10-11detec1onlimit,i.e.dmag=26.0•  Exquisite(LO)WFS&C:limitWFfluctuaFonsandsensiFvitytothem

•  LargestableDMsandelectronicdrivers:

o  atleast64x64for1”OWAat0.6µmwitha4mo  256x256for15mLUVOIR(?)

•  DualpolarizaFonopera1onstronglypreferred:

o  Higherthroughputo  EnablesPDIo  Planetreflectedlightpolarimetricstudies(e.gtalkbyT.Meshkat)o  Affectstelescopedesign(f#=2.5)

•  HighContrastObservaFonsofBinaries•  LUVOIR15m:alloftheabove,forasegmentedprimarywithcentralobscuraRon

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Raw Starlight Suppression •  Rawcontrastof~10-10orbe{erfrom2.5to32λ/DIWA,with:

o  InstantaneousBWof20%.o  High“core”throughput.o  DualPolariza1on.

•  CurrentStateoftheArt:o  WFIRSTlabdemonstra1onof10-9rawcontrastbtw3-8λ/D,10%BWaround

550nmanddualpolariza1on(HLC,Jun-ByoungSeoetal2017).o  Previousdemonstra1onsof4to6x10-10halfdarkholewithpolarizedlaser

lightand“friendlier”pupil(Trauger&Traub2007,Serabyn2010TDEM)

•  On-goinglabdemonstra1onsforunobscuredpupils:o  Serabynetal.2014TDEM,aimingfor<10-910%BWcontrastonfrom3-8l/D

foratleastonepolariza1onstate(2ifLSinPP)o  DecadalSurveyTestbedtarge1ng10-10contrastat2.5λ/Dand20%BWwithHLCandpossiblyVVCmasks

•  CurrentlyBaseliningcharge6vortexo  Highertheore1calresiliencetoloworderaberra1onso  Widelyusedatground-basedtelescopeso  HLCalsoconsideredasabackupduetoitshighTRLandtraceabilitytotheWFIRSTCGI.

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Low order WF sensing and control •  HabExCoronagraphErrorBudget(B.Nema12018,usingWFIRST-CGImethodology):

HabExCoronagraphErrorBudget ExoEarthIMG 500 nm 20% BW ViewedDate:

Δ magplanet Planet-StarFluxRatio Scenario: ExoEarthIMGREQ 25.0 REQ 100 ppt targetandreferencesystemassumptions alloc.integtime 50.0 hrsCBE 25.2 CBE 84 ppt notes: timetoSNR 32.6 hrs

1.scenarioincludesnoisefromdifferentialimaging Target Fid3:STM0.7RE12pc2.diffimagingassumesadditional20%time,onrefstar hoststarV 5.23 mag

FluxRatioNoise ExoZodi/Solar 3 XALLOC 14.3 ppt ref.star Δmag 3 magCBE 12.1 ppt pl.geom.albedo 36.7 %

pl.phaseangle 90 degpl.fluxratio 100 ppt

1 PhotometricNoise 2 SystematicNoise planetsep. 83 masDetectorandshotnoise contr.Stab.w/postproc. sys.distance 12 pcCBE 10.7 ppt CBE 5.6 ppt

FluxRatio/C_CG1.12

1.1 SpeckleShotShotnoiseofmn.speckle Postproc.factor SuppressionfromsubtractionaloneCBE 3.2 ppt f_pp 25% (4X) 5.11 x

1.2 DetectorNoise 2 RawContrast 3 ContrastStablityshotnoiseofplanetsignal 3.2 λ /DCBE 0.8 ppt CBE 102.0 ppt CBE 20.0 ppt

1.3 PlanetShotshotnoiseofplanetsignalCBE 3.0 ppt

1.4 ZodiShot 2.3 2.1 2.2 3.3 3.4 3.1Exo-Zodidominated "radial" "radial" B "azimuthal" C "azimuthal" E "radial" F ACBE 9.7 ppt CBE 0.01 ppt CBE 50.00 ppt CBE 50.00 ppt CBE 1.94 ppt CBE 0.01 ppt CBE 0.01 ppt

1.5 StrayLightShot 2.4 3.2Allstraylight "azimuthal" DCBE 1.0 ppt CBE 0.04 ppt CBE 1.81 ppt

TotalThroughput0.2 mas

CBE 14% Teles.throughput CBE 0.5 CBE nm

CBE 78%Jitter: 0.5 mas

CGThroughput CBE Drift: 2.0 mas CBE nm

CBE 17%Detec.Parameters

clockinducedcharge CGmaskthputdarkcurrent Teles.Align.Stab. TelOpt.WFEStab.readnoise CBE 20% relativetoPM total

SM TM PM 1017 pmDetec.Parameters trans 1 5 nm SM 269 pm

QE rot 1 5 nrad CBE TM 269 pm

3/15/2018

3.09

LOWFS/CPointing LOWFS/CWFE

mas 0.76

TelescopeACS Teles.WFEStability

ThermalDrift ThermalDrift Staticbkgdstd

JitterInduced ThermalDrift

JitterInduced StaticBkgdMean StaticBkgdMean

Vortex_X6

RequiredSNR7

TimeMargin35%

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Low order WF sensing and control: a mulJ-stage approach

•  Minimize“na1ve”telescopeWFji{er:o  UsecoldgasGAIA-like(orcolloidalLISA-Pathfinder)micro-thrustersratherthanreac1on

wheelsforfineal1tudecontrol(andaconven1onalmonoprophydrazinesystemforslewingandsta1onkeepingatL2)o  Usephasedarrayantennatofurtherreduceenvironmentalvibra1onandenablecon1nuous

sciencedownlink

•  MinimizeWFslowdri�so  Telescopethermaldesign(TBDSTOPanalysis)o  UseLASERmetrologytosenseandcorrectslowde-spacingofM2andM3wrtM1

•  SenseandcorrectresidualLoSji{eranddefocusduringscienceobs

o  WFIRST-likeZernikeWFSanalyzingstarlightreflectedoffcoronagraph(VVC:centraldot)o  UseWFIRST-likeseparatefast1p-1ltmirrorandfocusadjustment

•  Minimizesensi1vitytolow-orderaberra1ons

o  Usehighchargevortexcoronagraph(Ruaneetal.2018)o  VVC6preservesIWAandthroughput,whileimmunizingagainstloworderaberra1ons:

Compactlasermetrologybeamlauncher(J.Nissen)

VVC6btwpolarizers(credit:E.Serabyn)

LPFclusterofµ-thrusters(Credit:ESA/Airbus)

•  VVC6onclearcircularaperturecaninprincipletoleratemuchhigherloworderaberraLonsfluctuaLonsthancommonlybelieved:

•  100sofpmtonmfor(Z4-Z10)•  0.5masofrmsLp-Lltresiduals.

Loworderwavefronterrorrequirements(withjiser)

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AberraFon Indices AllowableRMSerror(nm)permode

n m charge6 charge8 charge10

Tip-1lt 1 ±1 5.5 18 31

Defocus 2 0 4.6 15 36

As1gma1sm 2 ±2 0.36 1.0 4.6

Coma 3 ±1 0.44 0.95 5.5

Spherical 4 0 0.32 0.81 6.7

Trefoil 3 ±3 0.0065 0.35 0.71

notrejectedfirst-orderrejec1on>first-orderrejec1on

With1mas(0.04λ/D)Fp-Fltjiser

MulF-StarDirectImagingObservaFonswithHabEx(Sirbu,Thomas&Belikov2017;Thomas,Belikov&Bendek2015)

Mul1-StarScienceSta1s1cs:-  517FGKstarswithin20pc-  259mul1-stars(op1calordynamical)-  193starslimitedat>1e-10

-  40starswithsep.<N/2λ/D

HabExassump1ons:-  D=4m-  λ=650nm-  λ/20RMSwithf-3powerspectrum-  48x48DMNote:Contrastfloorforanon-axiscoronagraph/starshadeduetounsuppressedoff-axiscompanionstar

On-axisblocker Off-axisblocker StarSeparaFonat<N/2λ/D*

StarSeparaFonat>N/2λ/D*

Notes

Coronagraph None(wavefrontcontrolonly)

MSWC SNMSWC Exis1ngmissionsarealreadycapableofMSWCwithnohardwaremodifica1ons.ThiscanbeextendedtoSNMSWCifthereisquil1ngontheDMoramildgra1nginthepupilplane

Coronagraph SecondCoronagraphmask

MSWC SNMSWC Thesecond(off-axis)coronagraphisnotnecessaryforawell-baffledtelescope,butmayrelaxthestrokerequirementontheDMforclosestars

Coronagraph Starshade SSWC SSWC Addingastarshadeeffec1velyreducesbinariestothesingle-starsuppressionproblem,butatasignificantincreaseinmissioncost

Starshade None(wavefrontcontrolonly)

SSWC SNWC Addingadeformablemirror(withoutacoronagraph)toastarshademissiontheoreFcallyenablesdouble-starsuppression

Starshade SecondStarshade Noac1vesuppressionrequired

Noac1vesuppressionrequired

Addingastarshadefortheoff-axisstareffec1velyreducesbinariestothesingle-starsuppressionproblem,butatasignificantincreaseinmissioncost

Starshade Coronagraph SSWC SNMSWC Theoff-axiscoronagraphisnotnecessaryforawell-baffledtelescope,butmayrelaxthestrokerequirementontheDMforclosestars.[BM:needsmildgra1nginthePP].

SSWC=SingleStarWavefrontControl(WC),MSWC=Mul1-StarWC,SNWC=Super-NyquistWC,SNMSWC=Super-NyquistMul1-StarWC

SCENARIO SOLUTIONS *AssumingDM=NxNactuators

Conclusions

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•  Wefindthata4mopFmizedoff-axistelescope/coronagraphassemblyshallbeabletodetect12+18–8exo-EarthsintheHZaroundnearby(<16pc)sunlikestarsandhundredsofothertypesofplanets

•  SmallIWAinλ/Dunits,high“core”throughput,andlowsensi1vitytoaberra1onsmakethismoderatesizetelescopesolu1onscien1ficallycompelling,costeffec1veandwithintechnicalreachforaphaseAstartinthemid2020s.

•  Anexternalstarshadeprovidesthemostefficientwaytospectrallycharacterizetheseplanets,yieldingspectraofallexo-Earthsand>50%ofplanetsdetectedbetween0.3and1micron

•  HabExstudyInterimreportwillbepubliclyavailablethissummer:h{ps://science.nasa.gov/astrophysics/2020-decadal-survey-planning•  MainTBDsbyfinalreport:

o  IncorporatebinarystarsWFS&Cschemeo  FullycompleteSTMusedtoderivetechrequirements,e.g.molecularabundancethresholddetec1onlevelrequirementso  Fullyassessscienceyieldsensi1vitytoastroandinstrumentuncertain1eso  Streamlinestarshadedesigno  ConducttradeofGOvsexoplanetsurvey1mefrac1onsforprimary5yrmissiono  Conductend-to-endSTOPmodelingtofinalizecoronagrapharchitecturetrade(VVC6orVVC8,HLC)o  FinalizenearIRdetectortradeo  ExploreArchitectureop1onB

•  Maindevelopmentsinthe10yearsaheadforHabExhighcontrastcoronagraphy

o  Demonstra1onofdualpolariza1on20%BW10-10contrastat~2-3 λ/D.o  Demonstra1onofWFCatrequiredlevelsàWFIRSTCGIwillprovideo  QualifylargerformatDMs

Back-UpSlides

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