ENCELADUS LIFE FINDER · 23 February 2017 . Enceladus: Ac-ve, Astrobiologically Relevant,...
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ENCELADUS LIFE FINDER Morgan L. Cable, Jonathan I. Lunine, Linda J. Spilker and the ELF Science Team 23 February 2017
Transcript of ENCELADUS LIFE FINDER · 23 February 2017 . Enceladus: Ac-ve, Astrobiologically Relevant,...
ENCELADUS LIFE FINDER
Morgan L. Cable, Jonathan I. Lunine, Linda J. Spilker and the ELF Science Team 23 February 2017
Enceladus: Ac-ve, Astrobiologically Relevant, Accessible Free sample, no need to dig or drill
2 Porco et al. (2014) Astron. J., 148, 3, 45. Images: NASA/JPL/SSI
• ~100 dis-nct, collimated jets emana-ng from Tiger Stripes that form a single plume
– Modulated by diurnal -dal flexing
Enceladus: Ac-ve, Astrobiologically Relevant, Accessible Free sample, no need to dig or drill
3 Glein et al. (2015) Geochim. Cosmochim. Acta, 162, 202-219. Hsu et al. (2015) Nature 519, 207-210. Images: NASA/JPL/SSI
• ~100 dis-nct, collimated jets emana-ng from Tiger Stripes that form a single plume
– Modulated by diurnal -dal flexing
• Plume feeds the E ring
– Decay -me constant of at least 100 years
– Silica nanograins suggest recent hydrothermal ac-vity
SiO2
2-8 nm
Plume Composi-on Organic-rich, sourced from the subsurface ocean
4 Waite et al. (2009) Nature 460, 487-490. Postberg et al. (2009) Nature, 459, 1098-1101. Images: NASA/JPL/SwRI/F. Postberg
• Vapor (Gas)
– H2O, CO2, CH4, NH3, heavier hydrocarbons, simple and complex organics
– Mass flux: 200 kg/s
• Solid (Grains)
– Water-ice, salts (mostly NaCl), SiO2, organics
– Mass flux: 50 kg/s (~10% of par-cles reach escape velocity)
Enceladus Awaits
Images: NASA/JPL
An ideal place to search for aqueous-based life
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Ice crust (2-10 km)
Global ocean (18-22 km)
Hydrothermal vents (>90°C)
South polar region with active jets
Rocky core
WE NEED TO GO BACK
Lessons from Cassini
Images: NASA/JPL
When ‘in situ’, do as the mass spectrometers do
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• In situ detec-on of biomarkers is key
– Remote sensing can support these measurements, but is no subs-tute
– Cassini Ion and Neutral Mass Spectrometer (INMS) and Cosmic Dust Analyzer (CDA) demonstrated the power of mass spectrometry for in situ plume science
• Limited sample size makes sample processing difficult
– Density of gas and grains in the plume is low (~5e-5 g collected on a 1 cm2 area for a 50 km flythrough)
– Simplicity over complexity (no GC or LC)
ELF as the Next Logical Step
Images: NASA/JPL/SwRI/F. Postberg
A robust instrument suite that targets plume gas and grains to search for life
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MASPEX Mass Spectrometer for Planetary Explora-on
ENIJA Enceladus Icy Jet Analyzer
• Target:Plumegas• Extendedmassrangeforheavyorganicmolecules• Enhancedmassresolu9onforcri9calisotopes• EnhanceddynamicrangeforhighS/N• Improvedsensi9vity(beAerthan1pptwithcryotrap)forrarenoblegases
• Target:Plumegrains• Heritage:GioAo,StardustCIDAbutimprovedionop9cs,iondetector,spectraprocessing
• Segmentedtargetforlowandhigh-ratespectramode(composi9onalprofilewith100mspa9alresolu9on)
• Completecomposi9onofeachicegrain,overawidemassrange
Pre-Decisional–ForInforma9onandDiscussionPurposesOnly
Plume Modeling
Images: B. Teolis/B. Southworth
Know before you go
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Plume Gas Model Plume Grain Model
Pre-Decisional–ForInforma9onandDiscussionPurposesOnly
ELF Mission Ops
Images: NASA/JPL
Life detecBon on the fly
9 Pre-Decisional–ForInforma9onandDiscussionPurposesOnly
• 10flybys,eachat5km/s
• 62-dayorbitallowsample9metosetinstrumentparametersforthenextflyby
Ambient Science
Mode
Comm
OTM
DeSat
Solar Array Slew
Comm
OTM(inc. Warm-Up)
S/c slew to flyby attitude
Quicklook comm
Solar Array and s/c slew to
flyby attitudeOTM
Comm
Cryo Science Mode
Cryo Science Mode
Cryo Science Mode
~1500 WhrRecharge (10 days)
~500 WhrRecharge (3 days)
Only period where
arrays are not pointed
at Sun (5 hours)
DeSat
Battery Recharge Mode
Science Mode
Slewing Mode
Prop Mode
Comm Mode
(OTM = Orbit Trim Maneuver)
ELF Science Inves-ga-on
Images: NASA/JPL/SwRI
Three objecBves, one profound quesBon: Is there life beyond Earth?
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Reac+onswithWater HydrothermalAltera+onNitrogenasanIndicator
1a.Determinetheoriginalmolecularcarrierfornitrogenasanindicatorofthedegreeofvola9leevolu9ononEnceladus.
1b.Quan9fythefrac9onofthevola9lepopula9onthathasnotreactedwithliquidwater.
Science Objec-ve 1: Evolu-on Determine if Enceladus’ vola-les, including organics, have evolved over -me.
1c.Confirmiftheoceanhasbeen,oris,incontactwithhydrothermalsystemsatitsbase.
Pre-Decisional–ForInforma9onandDiscussionPurposesOnly
ELF Science Inves-ga-on
Images: NASA/JPL
Three objecBves, one profound quesBon: Is there life beyond Earth?
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RedoxEnergy pHTemperature
2a.Determinethetemperatureoftheoceanandpossiblehydrothermalsystemstowithin100K.
2b.Quan9fytheamountofredoxenergyavailable.
2d.DeterminethepHoftheoceantowithinanaccuracyof1unit.
Science Objec-ve 2: Habitability Determine if the ocean of Enceladus sa-sfies the basic requirements of habitability.
Oxida+onState
2c.Determinetheoxida9onstateoftheocean.
Pre-Decisional–ForInforma9onandDiscussionPurposesOnly
ELF Science Inves-ga-on
Images: NASA/JPL
Three objecBves, one profound quesBon: Is there life beyond Earth?
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MembraneMolecules IsotopicTrendsAminoAcids
3a.LookforpaAernsintheaminoaciddistribu9onindica9veofbiologicalsynthesis,e.g.underrepresenta9onofglycinerela9vetootheraminoacidsthatareenerge9callymoredifficulttoform.
3b.Determinethelong-chainfaHyacid(C12–C30)distribu9ontolookforpaAernssuchastheeven-odddisparityduetoC2addi9oninbiologicalsynthesis.
3c.Determinethehydrocarbonabundancedistribu9on,D/Hra9oandthe13C/12Cdistribu9oninhydrocarbonsandCO2,tolookforpaAernsconsistentwithbiologicalsynthesis.
Science Objec-ve 3: Life Determine if the plume of Enceladus contains chemical signatures of biology.
Pre-Decisional–ForInforma9onandDiscussionPurposesOnly
A Life Inves-ga-on Within Reach
Images: NASA/JPL
MulBple, independent tests for life shrink the ambiguity box
13 Pre-Decisional–ForInforma9onandDiscussionPurposesOnly
Enceladus Awaits
Images: NASA/JPL
An ideal place to search for aqueous-based life
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• Thereisdefini9veevidenceofasubsurfaceoceanwithorganics,salts,andfreeenergy.
• TheplumeofEnceladusincludesoceanmaterialandisreadilyanalyzedforevidenceoflife—agoaloftheEnceladusLifeFinder.
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Acknowledgements So long, and thanks for all the fish
• JonathanLunine,PrincipalInves9gator
• HunterWaite,DeputyPI
• LindaSpilker,ProjectScien9st
• FrankPostberg,ENIJAInstrumentScien9st
• TimBrockwell,MASPEXInstrumentScien9st
• KarlaClark,CaptureLead
• KimReh,SolarSystemExplora9onMissionFormula9on
• BrentSherwood,SolarSystemExplora9onMissionFormula9on
• Theen9reELFTeam
Jet Propulsion LaboratoryCalifornia Institute of Technology
