NASA Technical Reports Server (NTRS) 20120002880: Search for Olivine Spectral Signatures on the Surface of Vesta

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by  NASA Technical Reports Server (NTRS)

GeophysicalResearchAbstracts
Vol.14,EGU2012-10814-1,2012
EGUGeneralAssembly2012
©Author(s)2012
Search for olivine spectral signatures on the surface of Vesta
E.Palomba(1),M.C.DeSanctis(1),E.Ammannito(1),F.Capaccioni(1),M.T.Capria(1),M.Farina(1),A.
Frigeri(1),A.Longobardo(1),F.Tosi(1),F.Zambon(1),H.Y.McSween(2),D.W.Mittlefehldt(3),C.T.
Russell(4),C.A.Raymond(5),J.Sunshine(6),andT.B.McCord(7)
(1)IAPS-INAF,Roma,Italy([email protected]),(2)UniversityofTennesse,KnoxvilleTNUSA,(3)Johns
HopkinsUniversityAppliedPhysicsLaboratory,LaurelMDUSA,(4)UCLA,LosAngeles,CAUSA,(5)CaltechInstitute
TechJetProp.Lab.PasadenaCAUSA,(6)UniversityofMaryland,CollegePark,MD,USA,(7)BearFightInstitute,22
FiddlersRd.,WinthropWA98862USA
TheoccurrenceofolivinesonVestawerefirstpostulatedfromtraditionalpetrogeneticmodelswhichsuggestthe
formation of olivine as lower crustal cumulates. An indirect confirmation is given by their presence as a minor
componentinsomesamplesofdiogenitemeteorites,theharzburgiticdiogenitesandtheduniticdiogenites,andas
olivine mineral clasts in howardites. Another indication for this mineral was given by interpretations of ground-
basedandHubbleSpaceTelescopeobservationsthatsuggestedthepresenceoflocalolivine-bearingunitsonthe
surfaceofVesta.
TheVIRinstrumentonboardtheDAWNmissionhasbeenmappingVestasinceJuly2011.VIRacquiredhyper-
spectralimagesofVesta’ssurfaceinthewavelengthrangefrom0.25to5.1µmduringApproach,SurveyandHigh
AltitudeMapping(HAMO)orbitsthatalloweda2/3oftheentireasteroidsurfacetobemapped.TheVIRoperative
spectralinterval,resolutionandcoverageissuitableforthedetectionandmappingofanyolivinerichregionsthat
mayoccurontheVestasurface.
Theabundanceofolivineindiogenitesistypicallylowerthan10%butsomesamplesricherinolivineareknown.
However, we do not expect to have extensive exposures of olivine-rich material on Vesta. Moreover, the partial
overlapofolivineandpyroxenespectralsignatureswillmakeolivinedifficulttodetect.
Different spectral parameters have been used to map olivine on extraterrestrial bodies, and here we discuss the
differentapproachesused,anddevelopnewonesspecificallyforVesta.Ournewmethodsarebasedoncombina-
tionsofthespectralparametersrelativetothe1and2micronbands(themostprominentspectralfeaturesofVesta
surfaceinthevisibleandtheinfrared),suchasbandcenterlocations,banddepths,bandareas,bandarearatios.
BeforethedirectapplicationtotheVIRdata,theefficiencyofeachapproachisevaluatedbymeansofanalysisof
laboratoryspectraofHEDmeteorites,pyroxenes,olivinesandtheirmixtures.