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.