EUROPAINTHEJUPITERSYSTEM:

FROMFORMATIONTOSEARCHFORLIFE(part2)

EUROPAINTHEJUPITERSYSTEM

Europahabitablezone.OceanworldsEuropabiosphere

OUTSTANDINGSCIENCEQUESTIONSFROMFORMATIONTOSEARCHFORLIFE

SOLVENTLiquidwater

ChemicalELEMENTS(CHONPS,metals…)

AvailableEnergyforLife

LIFEon Earth

HABITABILITYREQUIREMENTS

Clement conditions(pH,T,salinity,

H

Liquidwater

FUNCTION DESCRIPTION

Usesasreactant takespartinmanymetabolicreactions.•e.g.hydrolysisofsugar,rawmaterialforphotosynthesis.

Usesassolvent goodsolventforinorganicandmanysmallorganicsubstances.

Actsasmediumfortransportation

liquidnature,canflowfromoneareatoothers.•manychemicalscandissolveinit.

Actsasmediumforchemicalreaction

manychemicalscandissolveinit.•noteasilysubjectedtolargetemperaturefluctuation,thusreactionscantakeplaceinaconstantrate.

Providessupport providesturgiditytosupportherbaceousplantsandsmallorganisms•providesbuoyancyforaquaticorganisms

Othersdecreasesbodytemperaturebyevaporationofwaterfrombodysurfacee.g.sweat•necessaryforformingbodysecretione.g.digestivejuice•mediumforfertilizationofeggsandspermsinmammals

HABITABILITYREQUIREMENTS

KeyTheelementsusedbylivingorganismseitherin:

- structuralmacromolecules(proteins,lipids)- energytransformation- electrontransferchains- energysources,andasoxidantsorreductants

MineralSurface Elementalcomposition Properties

Basaltminerals Si,O,Fe MajormineralsurfaceonearlyEarth

Apatite Ca,PO42- Primaryphosphatemineral

Clays Si,Al,O Canorganizeorganicsintofilmsandcatalyzepolymerizationreactions

Pyrite FeS2 Sourceofreducingpower

Calcite CaCO3 Chiral surfaces;concentrateorganicssuchnucleotidesfrommodels

Quartz SiO2 Chiralsurfaces

Ultramaficminerals Fe,Mg GeneratehydrogenandorganiccompoundsfromCO2

Borateminerals B Catalyzethesynthesisofribose

(Wackettetal.2004)

(ModifiedfromDeamer,2007)

HABITABILITYREQUIREMENTS

The “Unity of Metabolism” predicts that organisms (even with different biochemistries than Earth organisms) on any active planet (water) will use the same chemical energy sources and electron acceptors and donors as Earth organisms

A variation of “follow the energy”, Hoehler, Amend and Shock, (2007); Shock and Holland, (2007)

LightsourcePhotosynthesis,Radiolysis,generationofoxidants

ChemicalsourceRedox process

Othergradientsthermal,osmotic…

HABITABILITYREQUIREMENTS

EUROPAASAPOTENTIALHABITATOUTSTANDINGSCIENCEQUESTIONSWhyEuropastandsoutasapotentialhabitat?

Distributionofwateratdepthoceanshallowchambers/subglacial lakeswater-rockinteractions

ReservoirspotentiallyconnectedwiththesurfaceEndogenicmaterialscanprovidecluesaboutaqueousreservoirs

Energy/geologicalactivity.InteractionswiththeobjectsintheJupitersystemHydrothermalsystemsandchemicaldisequilibriaMaintaintheliquidwaterandrock-waterinteraction

Buildingblocksandgeochemicalcycling

Exchangesbetween layers

Explain• Aqueousreservoirsinthesubsurface• Bio-essentialelements• Availableenergyforlife

Darkbiosphereundertheiceactivetoday.Abiogenesisinhydrothermalsystems

Asecondoriginoflife.Convergentevolutionasaconsequenceofabiogenesis

Evidencesoflife.Searchingstrategy

WhyEuropaisthebestplacetosearchforextantlife?

• MICROBIALECOSYSTEMS:CHEMOTROPHIC• Distributioncontrolledbyhydrothermalactivity,whichprovideprimarynutrients

(H2,CH4,ketones)• Surfacebounded,notfree-living• Nocarbonatematsasdochemotrophiccoloniesaroundterrestrialsmokers

becausetheyneedsulfate(oxigenated environment),andPabovethelysocline

???

THEPOTENTIALBIOSPHERE

FROMFORMATIONTOSEARCHFORLIFE

POTENTIALBIOSPHERE

Universalfeatures ofany kindofextraterrestrial lifeencompass:molecularreplication,cellularization andmetabolic networks.Fromthese systemic propertiesmorepreciseconvergentbiosignatures,i.e.potentialmolecularidentities