Post on 06-Aug-2020
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AdvancingscienceoftheMoon:Progresstowardachievingthe
goalsofTheScientificContextforExplorationoftheMoon report
BrettW.DeneviSamuelJ.LawrenceJackO.BurnsBarbaraA.CohenAmyF.FaganWilliamM.FarrellLisaR.GaddisJosephA.HamiltonKristenK.JohnGeorgianaY.KramerDavidJ.LawrencePaulG.LuceyFrancisM.McCubbinCliveR.NealLillianR.OstrachNoahE.PetroCarleM.PietersMarkS.RobinsonCharlesK.ShearerG.JeffreyTaylorReneeC.Weber
AdvancingScienceoftheMoonSpecificActionTeam
TheASMSATwasrequestedbyJimGreenandcommissionedbyLEAG;metinAugustinorderto:
• Evaluateprogressonlunarsciencegoalssincethe2007ScientificContextforExplorationoftheMoon(SCEM)report
• Considerconceptsrelatedtoscienceimplementation,aswellassecondaryscienceopportunities,outlinedintheoriginalSCEMreport
• Noteanynewlunarscienceconceptsthathavebecomeapparentsince2007
2007SCEMreport
• NationalResearchCouncilstudyperformedattherequestofAssociateAdministratorofSMD
• ProvideguidanceonthescienceenabledbythenewlyestablishedVisionforSpaceExploration(ESMD-ledlunarmissions)
• “NASAneedsacomprehensive,well-validated,andprioritizedsetofscientificresearchobjectivesforaprogramofexplorationoftheMoon”
8PrioritizedScienceConcepts• 1:Thebombardmenthistoryoftheinner solarsystemisuniquely revealedontheMoon
• 2:Thestructureandcomposition ofthelunarinteriorprovide fundamentalinformation ontheevolution ofadifferentiatedplanetarybody
• 3:Keyplanetaryprocessesaremanifestedinthediversityoflunarcrustalrocks• 4:Thelunarpolesarespecialenvironments thatmaybearwitnesstothevolatilefluxoverthelatterpartofsolarsystemhistory
• 5:Lunarvolcanismprovidesawindow intothethermalandcompositionalevolutionoftheMoon
• 6:TheMoon isanaccessiblelaboratoryforstudying theimpactprocessonplanetaryscales
• 7:TheMoon isanaturallaboratoryforregolithprocessesandweatheringonanhydrousairlessbodies
• 8:ProcessesinvolvedwiththeatmosphereanddustenvironmentoftheMoonareaccessibleforscientificstudywhiletheenvironment remainsinapristinestate
Top11Goals
• 1a– testcataclysmhypothesis• 1b– ageofSPA• 1c– preciselunarchronology• 4a– compositionanddistributionofpolarvolatiles• 3a– extent/compositionofprimaryproductsofdifferentiation• 2a– thicknessofcrust,variability• 2b– stratificationofthemantle• 8a– lunaratmosphere• 2c– size/composition/stateofthecore• 3b– variety/age/distribution/originoflunarrocktypes• 8b– electrostaticallytransporteddust
Advancesinlunarscience• SincetheSCEMreport:• Kaguya,Chang’e 1,Chandrayaan1,LRO,LCROSS,Chang’e 2,GRAIL,LADEE,Chang’e 3• Restorationandreexaminationofolderdatasets• Technologicaldevelopments• Advancesinmodeling• Newideas!
• IftheImbrium impactoccurredonEarthitwouldhave:• Vaporizedtheoceans• Sterilizedthecrusttodepthsof100sofmeters
• WasthereaspikeoflargeimpactsaroundthetimeImbrium formed?• EmergenceoflifeonEarth• Migrationofgiantplanets• DeliveryofvolatilestotheinnerSolarSystem
Example:Goal1aTestthecataclysmhypothesisbydeterminingthespacingintimeofthelunarbasins
• HadbeengeneralconsensusaboutrelationshipofsamplestoImbrium,Serenitatis,andNectaris
• Serenitatis:• SculpturedHillsdeposits depositedasImbrium
ejectaratherthanSerenitatis(Spudis etal.,2011;Fassett etal.,2012)
• U-Pb datingofSculpturedHillsmaterialsupportsImbirum origin,Ar distributionlessstraightforward(Merceretal.,2015;Thiessenetal.,2017)
• Nectaris:• YoungestclastsinaluminousDescartesbreccias are
coevalwithKREEP-richcrystallinemeltrocksthatarethebestcandidatesfromImbrium ejecta,supportgeologicalinterpretationofDescartesformationasImbrium ejecta(Normanetal.,2010)
• IfSculpturedHillsandDescartesFormationareImbrium ejecta,removesageconstraintsonbasinsolderthanImbrium andreopensthepre-Imbrian impacthistorytodebate
Oblique viewofSculpturedHillsatApollo 17site
Example:Goal1aTestthecataclysmhypothesisbydeterminingthespacingintimeofthelunarbasins
• Theimportanceofthisquestionhasonlygrowninthepastdecade
• Identifiedprobabledepositsofbasinmeltforfutureinsituanalysisand/orsamplereturn
• Withoutgeochemicalandgeochronological analysesofkeymeltdeposits, thespacing intimeoflunarbasinsremainsunknown
Example:Goal1aTestthecataclysmhypothesisbydeterminingthespacingintimeofthelunarbasins
Orientalebasinimpactmelt
ASMSATReport
• Progresstowardeachgoalevaluated• Eachsectionendswithsummaryofprogressstillneeded• Noefforttoreprioritize• IdentifiednewConceptsandGoals
Thelunar‘water’cycle
• VolatilesscatteredacrossfourConceptsofSCEMreport• Workfromthelastdecadepointstocyclewiththreecomponents:• Primordial(interior)water• Surficialwater(linkedtosolarwind)• Polarwater(sequestered)
• Identifyandcharacterizetheselunarvolatilereservoirsandevaluatetheirinterrelations• Compositionandvariabilityofendogenousvolatilesentrainedinvolcanicproducts
• Sourcesofmid-latitudesurfacehydroxylandwater,determinehowitmigrates
• Determinesource(s)ofpolarvolatiles
TheoriginoftheMoon• AkeygoalofstudyingtheMoon:betterunderstandtheoriginandaccretionofplanets• Moon’sdeepinteriorisavaultcontainingcriticalinformationaboutitsinitialcompositionduringandimmediatelyafteraccretion• Specificgoals:
• timingofthecollision• mechanisms,timing,extentofvolatiledepletionintheMoon
• compositionoftheimpactor• conditionsandprocessesintheprotolunardisk
• conditionsandprocessesatthesurfaceofthelunarmagmaocean,compositionandlongevityofanearlyatmosphere
Elkins-Tanton,2013
Lunartectonismandseismicity• Greatlyexpandedhigh-resimagingledtodiscoveryofabundance oflobatescarps• Withoutplatetectonics:number,distribution,levelofseismicityoflobatescarps,provideinformationonMoon’sinteriorstructure,thermalhistory,andmechanism(s)ofheatloss• Inadditiontoglobalcontraction,maybeduetostressesfromtidesandrecession– activetoday• Lobatescarpsexplainshallowmoonquakes?
• Ifso,regionswithactivescarpswouldbetargetedforseismicanalyses,butavoidedforlandedassetssuchasoutposts
ASMSATreportconclusions• ConceptsandgoalsoutlinedintheSCEMreportremainrelevantafteradecadeofprogressinlunarscience• Nearlyallhadatleastsomeprogress;nonewere“done”
• Newconceptsandgoalshaveemerged• Lotslearned,lotstodo
MariusHills
WearenowinamuchstrongerpositiontotakeadvantageofladedmissionsandidentifyideallandingsitestoaddresstheSCEMgoals
Whilethereisstillrealprogresstobemadefromorbitalmissions,theadvancementofmanyofthesegoalsrequireslandedmissions
JacksonCentralPeak
LandedmissionsforLunarScience
Progress is not a shot in the dark,but a series of logical steps.
RobertH.Goddard.