25km
RationaleforLandingSitesatLunarPyroclastic
Deposits
Lisa GaddisUSGS Astrogeology Science Center
Jan 11, 2018Lunar Science for Landed Missions Workshop
Alphonsuscraterwith11pyroclasticvents
Outline
� Overviewofthelunarpyroclasticdeposits
� Resourcepotential
� ISRU,AccessibilityandTraversability
� Recommendationsforlunarlandingsites
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LunarPyroclasticDeposits
Explosivelyemplacedvolcanicdeposits◦ Diffuseboundaries, associationwithvents
Ancient,byassociationwithlunarmaria◦ Mostbasaltseruptedduring theLateImbrian (3.6to3.8BYago)
◦ Hiesinger etal.(2000)cratercounts
Globallydistributed◦ Observedalongmarginsoflunarmaria
◦ Oftenassociatedwithfloor-fractured cratersinfaultedregions
Rangeofsizes(~50,000to3km2):
◦ VeryLarge=50000– 1000(22)
◦ Large=<1000– 400(19)
◦ Medium=<400– 200(12)
◦ Small=<200– 100(18)
◦ VerySmall=<100– 3(16)
31.11.18
87 Gustafson,etal.,2012
}Gaddisetal.,2003
LUNARSCIENCEFORLANDEDMISSIONSWORKSHOP
Alphonsus NE floor ventsKaguya MI color, 20 m/pixel, ~24 km across
RegionalPyroclasticDeposits� Formedbyfire-fountaining(Head&Wilson,2017)
� Highvolatilecontent(H,H2O,CO,SO2),ballistic
trajectories
� Widelydistributed, ~thindeposits
� Abundantjuvenilematerial� Quenchedglass,crystallinebeads(oftenHiTiO2)
� TypeExamples� TaurusLittrow(Apollo 17)
� RimaBode,SinusAestuum,Sulpicius Gallus
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Rima Bode Regional Pyroclastic Deposit (~6600 km2)Lunar Orbiter IV 109, ~120 km across
Ap 17 glass &crystalline beads
(G. Ryder)Bennettetal.,2016
LUNARSCIENCEFORLANDEDMISSIONSWORKSHOP
LocalizedPyroclasticDeposits� FormedbyVulcanian-styleeruption
� Intermittent,violentexplosioncausedbydegassing
nearsurface,disruption ofaplugasmagmarisesin
adike(Head&Wilson,1979)� Volatile:CO-richgasproducedbygraphite
oxidation(Fogel &Rutherford,1995)� Mixedjuvenileandnon-juvenilematerials
� Glass,crystallinebasaltic (HiFeO),fragmentedcountryrock
� TypeExample� Alphonsuscrater� Oppenheimer crater
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Alphonsus crater,FloorVent#6
KaguyaTerrainCamera
Bennettetal.,2016
LUNARSCIENCEFORLANDEDMISSIONSWORKSHOP
GloballyDistributed
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Pyroclasticdeposits (Gaddis etal.,2003;Gustafsonetal.,2012)
Floor-fracturedcraters(Jozwiak etal.,2015)
Fractures/faults(Wilhelms, 1987)
ResourcePotential
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• Relativelyunprocessedmaterialsfromdeepwithin the
lunarmantle(~300to400kmdepths)
◦ HighMg/Al,MgO,mg#;lowerAl2O3 andCaO thanmarebasalts
• Interiorcrystalsofolivine, spinel, ilmeniteneedles,etc.
• Uniformgrainsize,~40microns
• Surficialgeochemicalenrichments in>25volatileelements
• e.g.,Au,Ag,Cu,Cd,F,S,Z(McCubbin etal.,2015)
• Contain FeO:16to24wt %
• VariableamountsofTiO2,relatedtocolor
◦ Green:<1to5wt%◦ Yellow:5to9wt %
◦ Orange:9to14wt %◦ Red-black:>14wt%
• 25varieties ofvolcanicglassdescribedbyDelano(1986),severalothersidentifiedsince
Comprisedof‘primitive’glassandquenchedspheres
ResourcePotential#2
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IndigenousMagmaticWater
• TheMoonisgenerallyvolatile-depleted
•BUT,recentsampleanalysesofmeltinclusionsin
glasssamplesfromAp15,Ap17foundevidencefor
waterandothermagmaticvolatilespecies
• ~30to36ppmofmagmaticwaterinAp 15glass
beads(Saal etal.,2008)
• Correlationswithothermagmaticelements(Chlorine,
Fluoride, Sulfur)
• Concentrationofvolatilesdecreasedtowardedges,
indicatingtheywerenotcontaminantsfromEarth
• 270-1200ppmH2OinolivinecrystalsfromAp17
(Hauri etal.,2011)
• Fromaprimarylunarmagma
• Sourcewaterabundances of80-440ppm,comparableto
MORBs
• SummarizedbyMcCubbin etal.,2015;Hauri eal.,
2017
Apollo 15 green glass beads about 0.1 mm across
(Ap 15 S79-32188)
ResourcePotential#3
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MappingofLunarWater• UseofMoonMineralogyMapper(M3)data,quantitativeanalysisofstrengthofthe2.85-micronband
(ESPAT),mappingofOH- and/orH2O-bearingminerals
• Waterabundancesupto150ppmatlargepyroclasticdeposits,300to400ppmnearvents
ESPAT=effective
singleparticle
absorption
thickness
Milliken&Li,2017
ResourcePotential#4
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ExogenousVolatiles• Solar-wind implantedvolatiles(e.g.,H,3He)inmature,Hi-Ti lunarregolith
• Evenlydistributed intop2-3m,requiresheating (300°-900° C)torelease(Fegley &Swindle,
1993)
Fa&Jin,2007
Estimatedconcentrationof3He(ppbbymass) inthelunarregolith
Nearside FarsideCrawford,2015
In-SituResourceUtilization
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• Useofin-situlunarresourcescanreducecostsofsurfaceoperations
• H2O~oxygen,drinkingwaterforlifesupport
• H~rocketfuel,reducingagent
• C,N,Scouldsupport lunaragriculture
• PyroclasticdepositsarerichinFeO &TiO2
◦ Extractionofoxygen(>20methodstochoosefrom;Taylor&Carrier,1992)
◦ Reductionofilmeniteispopular;requiresH,energy
• Surveymoderequiresmobility,accessibility,traversability
• Supports horizontalassessmentoffeedstock,estimatesofthicknessandverticaldistributionfromventoutward,determinationofconsistencyofmaterials
• Samplereturnprovidesmoreprecisedeterminationsofcomposition, calibrationforremotemapping
• Ilmenitecontent
• Presenceofolivine
• Indigenouswater
• Surface-correlatedandsolar-wind-implantedvolatiles
FromLarryTaylor
3-DPrintedMoonBase(ESA)
LunarLandingSites
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• SKGstobeaddressedatlunarpyroclasticdeposits◦ Understandingplanetaryvolcanicprocesses
◦ UnderstandingtheMoon’sresourcepotential
◦ Understandingthenature&distributionoflunarvolatiles
• Sciencequestions(examples)
• Howoldarethelunarpyroclasticdeposits?
• Aresomeeruptionstylesmorelikelytobeassociatedwith
depositswith indigenouswater?
• Whichdepositscontainolivinethatcanbetiedtodeeplunar
interiororigin?
• Howthick/uniformarethedeposits?Doesthicknessvary?
Howmuchmaterialispresent?
• Whatsites?
• “Blackspot”locations,highiron,titanium,H,H2O,surface-
correlatedvolatiles,water
• Taurus-Littrow,Sulpicius Gallus,RimaBode,Vaporum, etc.
• Humorum
• Aristarchusplateau(Jawinetal.,thissession)
3DSinusAestuum,RimaBode(Kaguya MIdrapedonSLDEM15)
ESPAT(Milliken&Li,2017)
LunarLandingSites
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Thanksforlistening!
LunarLandingSites
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•ExampleLandingSite:Humorum
• Regionalextent(1500km2),smooth-surfaced,Hi-FeO
• Precursorremotecharacterization
• Highspatialresolution(<100mpp),hyperspectral imagertomap~3
micronabsorptionband
• Characterizeabundance,distributionofmaficmineralsandindigenous
waterindetail
• UseLROCdata(~1mpp)fordepositthickness estimates, boulder&crater
hazards
• UseLOLAdatatodevelopslopemaps
• Rovermission(groundcontactatmultiplesites)
• AlphaParticleX-raySpectrometer: Bulkchemistry
• NeutronSpectrometer:Measurebulkhydrogen,watercontentat
multiplesites
• Pancam colorimager:
• Multispectralmapping(composition)survey
• Observeanychange(s)withtime
• Samplereturn
• Multiplesamplesofmaturesoil,quenchedglass,crystallizedbeads
• Analysisofmagmatic water(abundance,distribution,etc.)
• Ground-truthforremotemeasurements
• Feedstockassessment andviabilityforin-situextraction
Milliken&Li,2017
