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THE HALLEY ARMADA

INSTITUTE OF SPACEANDASTRONAUTICALSCIENCE

european space agencyagence spatiale europ_enne

(NASA-CR-195725)(JPL) I4 p

RI/ ANational Aeronautics andSpace Administration

THE HALLEY ARMAOA N94-71808

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Z9/90 00025bi

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INTRODUCTION

On February 9, 1986, Halley'sComet makes its 30th recordedperihelion passage of the Sun,but its first passage of the spaceage. It was inevitable that thismost famous of all cometswould receive unprecedentedattention, but the actual magni-tude of the effort has surprisedeven most of those involved init. Coordination of the various in-ternational efforts in space andon the ground has been suppliedby the Inter-Agency ConsultativeGroup (IA CG), whose single goalhas been to maximize the scien-tific output of all participants.Some of the major componentsof the peaceful, scientific armadadedicated to Halley research aredescribed briefly in thisbrochure.

Comet Halley, 1910. (ML Wilsonand Las Campanas Observatories)

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U.S.S.R. VEGA SPACECRAFT

The Soviet Union launchedidentical VEGA spacecraft onDecember 15 and 21, 1984.Their interplanetary trajectoriesallowed flybys of Venus on June11 and 15, 1985, during whicheach spacecraft successfully re-leased a lander and an atmo-spheric balloon to explore theplanet. VEGA 1 will encounterComet Halley on March 6, 1986,at a velocity of 78 km/s andwith a miss distance of 104 kin.VEGA 2 will encounter thecomet on March 9, 1986, withits final aim point being deter-mined by results from VEGA 1. /

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The VEGA spacecraft. (SovietAcademy of Sciences)

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VEGA PAYLOAD 3

INSTRUMENT TYPE MEASUREMENTS

Imaging (2) Telescopes, 1200-ram and 200-mm focal length Structure of nucleus and coma

Spec trome ter

InfraredSpectrometer

Dust MassSpectrometerDust Counters(2)Neutral Gas MassSpectrometerIon MassSpectrometer(2 of 5 sensors)Plasma MassSpectrometer andElectron Analyzer(3 of 5 sensors)Energet ic ParticleAnalyzer

0?4 x 0?6 and 3?5 x 5?2 field-of-viewDetectors, CCDs with multiple filtersBest resolution - 180 mThree-channel, O. 12-0.35 #m, 0.35-0.9 #m,and 0.9-2.0 ILmSpatial resolution 3 x 6 arcmin in ultraviolet andvisible, 6 x 60 arcmin in infrared, all 1 o field-of-viewSpectral resolution 5 A in ultraviolet, 10 _ invisible, and 120 A in infraredPolarimetry in visibleThree-channel, 4-8 #m, 8-16 #m, and7-14 #m imagingSpatial resolution - 1 arcmin1 o field-of-viewDetector, HgCdTe at 80 KIonization-impact time-of-flight, M/AM - 150 for1- 110 amuMetal plates each with three piezoelectric sensorsforM > 10-10gPlasma-cloud counter for M = 10-10-10 -18 gTime-of-flight

Plasma WaveDetectors

Magnetometers(2)

Electrostatic analyzer 1-150 amu, M/AM _ 25,energy 15-3500 eVCylindrical retarding potential analyzerElectrostatic analyzers (2)3-5000 e V electrons50-25, 000 e V ionsCylindrical retarding potential analyzerSemiconductor detectors (2)Anticoincidence scintillator175 keV-few MeV electrons20 ke V- _ 30 Me V nucleonsLow frequency antenna with Faraday trap,O. I- 100 HzHigh frequency antenna, 0-300 kHzLangmuir probeFluxgate type on 5-m boomAccuracy O. 1 nT

Abundances and distribution ofatoms, molecules, and ionsin coma

Nucleus propertiesTemperature, size distribut ion, andabundance of dust in comaParent molecule spectraComposition from mass and numberof component dust atomsNumber and mass of impactingparticlesNumber and mass of atoms andmolecules in spacecraft vicinityFlux, mass, and velocity ofcometary ionsFlux and energy spectrum of solarwind electrons and ions

High-energy solar and galacticparticles, particles acceleratednear cometFlux of high and low frequencyelectromagnetic waves propagatingin cometary plasmaAmbient (DC) magnetic field

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EUROPEAN SPACE AGENCY GIOTTO SPACECRAFT

The European Space Agency(ESA) launched its Giotto space-craft on July 2, 1985. Flyby ofComet Halley is scheduled forMarch 13, 1986, at a velocity of69 km/s and at a distance of500 km sunward from thecomet's nucleus. This close tar-geting will be possible throughthe use of Intercosmos VEGAimages for final navigation.

Giotto approaching Comet Halley.(George Jones. courtesy ofSpace Frontiers Limited)

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GIO TTO PA YLOAD 5

INS TRUMENT TYPE MEASUREMENTS

Camera Telescope, 960-ram focal length Images of nucleus and innerDetector, CCD coma

Neutral MassSpectrometer

Ion Mass Spectrometer

Ion Cluster Composi tion

Dust MassSpectrometerDust Impact Detector

Optical ProbeExperimentMagnetometerPlasma Experiment

Energetic Particles

Electron Distribution

2 3 field-of-view, 4 filtersUltimate resolution - 30 mDual sensors (mass and energy)Sensitivity to 10 cm -3High resolution 1-35 amuModerate resolution to 86 amuHigh intensity range, up to 104 ions cm -3for energies to 1.5 keVHigh energy range, up to 8 ke V fordensities up to 102 ions cm -3Electrostat ic analyzer10 to > 230 amu10-3-10 4 cm-3Ionization-impact time-of-flight,M/AM - 150 for 1-110 amuMicrophones for M > 10-11 g.Capacitor sensor for M > 10-1u gIonization sensor for M > 10 -1 gPho topolarime ter30-mm focal length, f/2.58 filtersTriaxial ring-core fluxgate on antenna mastFast ion sensor, all masses, 10 eV-20 keVImplanted ion sensor, six mass groups(1-45 amu), 100 eV-70 keYSurface barrier detectorsElectrons _ 30 keVProtons >__100 keVParticles (Z >__2) _ 2. 1 Me VQuadrispherical electrostatic analyzer10 eV-30 keV360 o x 4 o field-of-view1 4 resolutionAE/E - O. 1AT -2 s

Abundance of each molecularmass of neutral gas

Abundance, mass, and energyof ions

Mass analysis of positive ionsand their hydratesAbundance of chemical elementsin the dust particlesAbundance and mass distributionfunction of coma dust particles

Scattering properties of dust andspatial densities of gas and dustAmbient (DC) magnetic fieldThree-dimensional velocitydistribution of positive ionsEnergy spectrum and direction ofenergetic particles from the Sun,in Halley bow shock, and inion tailDetermine accurate angulardistribution of suprathermalelectrons at fast rate

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JAPANESE SPACECRAFT

The Japanese Institute ofSpace and Astronautical ScienceUSA S) has launched Japan'sfirst two interplanetary space-craft, one to study Comet Halleyand one to monitor the solarwind environment in the comet'svicinity. Suisei, launched onAugust 19, 1985 (Japanesetime), on its interplanetary trajec-tory to study Comet Halley, willencounter the comet on March 8,1986, at a velocity of 70 km/sand a miss distance of less than106 km. The Sakigake space-craft was launched on January 8,1985 (Japanese time), and willbe within a few million kilome-ters of the comet in March1986.

The Suisei spacecraft. ( ISAS)Launch of the Sakigake space-craft on January 7, 1985. ( ISAS)

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SUISEI PA YLOAD 7

INS TRUMENT TYPE MEASUREMENTS

Ultraviolet Camera Ultraviolet telescope Abundance and distribution of2?5 x 2?5 field-of-view hydrogen in coma by study ofResolution 1 arcmin/pixel L_ (1216,4)Intensified CCD detector, detection limit1 kR at LeSpherical electrostatic energy analyzer5 x 60 field-of-view30 eV- 16 keV in 96 steps

Solar WindExperiment

Energy and direction ofelectrons and ions

SAKIGAKE PAYLOAD

INS TRUMENT TYPE MEASUREMENTS

Solar Wind Ions Faraday cup, collection area 70 cm 2 at Ion temperaturezero angle of attack /on densityBulk velocity

Ambient (DC) magnetic fieldMagne tome ter

Plasma Wave Probe

Triaxial fluxgate of ring-core typeon 2-m boomSensitivity < O. 1 nTDipole antenna, lO-m length, for electricfield measurementsSearch coil, 105 turns, ferrite core for magneticfield, frequency range 70 Hz-200 kHz

Plasma wavesRadio burstsAuroral radiationBernstein waves

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ICE PAYLOAD (Applicable to Comets) 9

MEASUREMENT INSTRUMENT CAPABILITIES

Plasma Electrons Spherical section electrostatic 5 < Ee

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U.S. ASTRO-1 MISSION

Astro-1 is a collection of in-struments designed for astro-nomical observations from lowEarth orbit. Carried aloft by aSpace Shuttle on March 6, 1986,the telescopes in the payload willstudy the comet for the availableperiod during each orbit.

Astro- 1 aboard a Space Shuttle.

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ASTRO- 1 EXPERIMENTS 11

INS TRUMENT MEASUREMENTS

Hopkins Ultraviolet Telescope (HUT) Spectra from 425 to 1850Wisconsin Ultraviolet PhotopolarimeterExperiment (WUPPE)Goddard Space Flight Center UltravioletImaging Telescope (UIT)Wide-Field Cameras [2] (WFC)

High spatial resolution photometry and polarimetryfrom 1300 to 3300High angular resolution imaging from 1216 to3200Tail photography from 3800 to 5000,4 and from5000 to 6500

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INTERNATIONAL HALLEY WATCH

The International Halley Watch(IHW) was organized in 1981 tocoordinate ground-based studyof Comet Halley and to assistHalley space missions wherepossible. Its goals are to (1) ad-vocate studies of the comet byany scientifically valid means,(2) coordinate the activities ofground-based observers to max-imize the scientific return of allinvestigations, (3) set usefulstandards for observations, (4)place the spacecraft missions inthe context of overall cometarybehavior, and (5) archive all theproperly documented data col-lected during the Halley appari-tion. The scope of the HalleyWatch has been broadened toinclude a Giacobini-Zinner Watchin support of the InternationalCometary Explorer.

The/nternational Halley Watchdisciplines.

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IHW RESEARCH AREAS

DISCIPLINE S TUDIES

Astrometry

Infrared Spectroscopy andRadiome tryLarge-Scale PhenomenaMeteor Studies

Near-Nucleus Studies

Photometry and Polarimetry

Radio Studies

Spectroscopy and Spectrophotometry

Orbital elements and evolution, ephemerides, nucleusand nongravitational forcesDust particle temperature and size distribution, albedoand energy balance, gas compositionMorphology of ion and dust tails, tail interactions withsolar wind and radiationDensity, mass, and composition of Halley meteorstreams (Orionids and Eta Aquarids)Dynamics of dust, ion, and neutral gas flows nearnucleus, nucleus morphology and dynamicsAbundances and distribution of major volatiles andnon volatilesGas production and composition, study of nucleus byradar (if possible), plasma studiesChemical and isotopic composition, gas temperaturesand velocity

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THE NEXT MISSION"COMET RENDEZVOUS

National Aeronautics andSpace AdministrationJet Propulsion LaboratoryCal ifornia Insti tu te of TechnologyPasadena, California

JPL 400-278, Rev, 2 10/85