Complete Course in Astrobiology

425 Pages·2007·4.479 MB·English

by  Gerda Horneck, Petra Rettberg

Complete Course in Astrobiology
Edited by
Gerda Horneck and Petra Rettberg
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(cid:1)2007WILEY-VCHVerlagGmbH&Co.KGaA,
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ISBN: 978-3-527-40660-9
V
Table of Contents
1 Astrobiology:FromtheOriginofLifeonEarthtoLifeintheUniverse
Andr(cid:1)Brack
1.1 GeneralAspectsofAstrobiology 1
1.1.1 HistoricalMilestones 1
1.1.2 SearchingforEmergingLife 3
1.1.3 TheRoleofWater 4
1.1.4 ThePhysicochemicalFeaturesofCarbon-basedLife 4
1.1.5 ClaysasPossiblePrimitiveRobots 6
1.2 ReconstructingLifeinaTestTube 7
1.2.1 TheQuestforOrganicMolecules 7
1.2.1.1 TerrestrialProduction 7
1.2.1.2 DeliveryofExtraterrestrialOrganicMolecules 8
1.2.2 SpaceExperiments 10
1.2.3 AttemptstoRecreateLifeinaTestTube 11
1.2.4 APrimitiveLifeSimplerthanaCell? 13
1.3 TheSearchforTracesofPrimitiveLife 14
1.3.1 Microfossils 14
1.3.2 OldestSedimentaryRocks 15
1.4 TheSearchforLifeintheSolarSystem 15
1.4.1 PlanetMarsandtheSNCMeteorites 15
1.4.2 Jupiter’sMoonEuropa 17
1.4.3 Saturn’sMoonTitan 18
1.5 TheSearchforLifeBeyondtheSolarSystem 19
1.5.1 TheSearchforRockyEarthlikeExoplanets 19
1.5.2 DetectingExtrasolarLife 20
1.6 Conclusions 20
1.7 FurtherReading 21
1.7.1 BooksandArticlesinBooks 21
1.7.2 ArticlesinJournals 21
1.7.3 WebSites 22
CompleteCourseinAstrobiology.EditedbyGerdaHorneckandPetraRettberg
Copyright(cid:1)2007WILEY-VCHVerlagGmbH&Co.KGaA,Weinheim
ISBN:978-3-527-40660-9
VI TableofContents
2 FromtheBigBangtotheMoleculesofLife
HarryJ.Lehto
2.1 BuildingBlocksofLife 23
2.2 BigBang:FormationofHandHe 25
2.3 FirstStars:FormationofSmallAmountsofC,O,N,SandPand
OtherHeavyElements 28
2.4 NormalModernStars,BulkFormationofC,O,N,S,PandOther
HeavyElements 29
2.5 TheFirstMolecules(COandH O) 35
2
2.6 InterstellarMatter 35
2.6.1 InterstellarClouds 37
2.6.2 InterstellarGrains 39
2.6.2.1 Formation 39
2.6.2.2 ObservedProperties 40
2.6.3 Ices 41
2.6.4 MoleculesintheGasPhase 42
2.6.4.1 ObservedProperties 42
2.6.4.2 FormationofH 43
2
2.6.4.3 FormationofCOandH O 44
2
2.7 GenerationofStars:FormationoftheSunandPlanets 44
2.7.1 AccretionDiskoftheSun 44
2.7.2 FormationoftheEarth 46
2.7.3 EarlyRainofMeteorites,Comets,Asteroids,andPrebioticMolecules 47
2.7.4 D/HRatioandOceans 49
2.8 FurtherReading 51
2.8.1 BooksorArticlesinBooks 51
2.8.2 ArticlesinJournals 51
2.8.3 WebSites 53
2.9 QuestionsforStudents 53
3 BasicPrebioticChemistry
Herv(cid:1)Cottin
3.1 KeyMoleculesofLife 55
3.1.1 DismantlingtheRobots 56
3.1.2 ProteinsandAminoAcids 58
3.1.3 DNA,RNA,andTheirBuildingBlocks 60
3.1.4 First“PrebioticRobot” 63
3.2 HistoricalMilestones 63
3.3 SourcesofPrebioticOrganicMolecules 69
3.3.1 EndogenousSourcesofOrganicMolecules 69
3.3.1.1 AtmosphericSyntheses 69
3.3.1.2 HydrothermalVents 70
3.3.2 ExogenousDeliveryofOrganicMolecules 71
3.3.2.1 Comets 71
3.3.2.2 Meteorites 73
TableofContents VII
3.3.2.3 Micrometeorites 74
3.3.3 RelativeContributionoftheDifferentSources 74
3.4 FromSimpletoSlightlyMoreComplexCompounds 75
3.4.1 SynthesisofAminoAcids 75
3.4.2 SynthesisofPurineandPyrimidineBases 76
3.4.3 SynthesisofSugars 78
3.4.4 SynthesisofPolymers 80
3.5 Conclusions 81
3.6 FurtherReading 82
3.6.1 BooksorArticlesinBooks 82
3.6.2 ArticlesinJournals 82
3.7 QuestionsforStudents 83
3.7.1 Basic-levelQuestions 83
3.7.2 Advanced-levelQuestions 83
4 FromMolecularEvolutiontoCellularLife
KirsiLehto
4.1 HistoryofLifeatItsBeginnings 85
4.2 LifeasItIsKnown 88
4.2.1 ThePhylogeneticTreeofLife 88
4.2.2 LifeisCellular,HappensinLiquidWater,andIsBasedon
GeneticInformation 88
4.2.2.1 GeneticInformation 92
4.2.2.2 TheGeneticCodeandItsExpression 94
4.3 LastUniversalCommonAncestor(LUCA) 96
4.3.1 ContainmentinaCellMembrane 97
4.3.2 GenesandTheirExpression 99
4.3.3 HypotheticalStructureoftheLUCAGenome 103
4.4 “Life”intheRNA–ProteinWorld:IssuesandPossibleSolutions 105
4.4.1 EvolutionarySolutions 106
4.4.2 SolutionsFoundintheViralWorld 107
4.5 “Life”BeforetheAppearanceoftheProgenote 108
4.5.1 TheBreakthroughOrganismandtheRNA–ProteinWorld 108
4.5.2 PrimitiveTranslationMachinery 108
4.5.3 OriginofRibosomes 109
4.6 TheRNAWorld 111
4.6.1 OriginoftheRNAWorld 113
4.6.1.1 PrebioticAssemblyofPolymers 113
4.6.1.2 TheBuildingBlocksoftheRNAWorld 114
4.6.1.3 WhereCouldtheRNAWorldExistandFunction? 115
4.7 BeginningofLife 117
4.8 FurtherReading 118
4.8.1 Books 118
4.8.2 ArticlesinJournals 118
4.9 QuestionsforStudents 120
VIII TableofContents
5 Extremophiles,thePhysicochemicalLimitsofLife(GrowthandSurvival)
HelgaStan-Lotter
5.1 ABriefHistoryofLifeonEarth 121
5.1.1 EarlyEarthandMicrofossils 121
5.1.2 Prokaryotes,Eukaryotes,andtheTreeofLife 123
5.1.3 SomeCharacteristicsofBacteriaandArchaea 126
5.1.3.1 CellWalls,Envelopes,andShape 126
5.1.3.2 LipidsandMembranes 127
5.2 ExtremophilesandExtremeEnvironments 127
5.2.1 GrowthversusSurvival 129
5.2.2 TheSearchforLifeonMars:TheVikingMission 130
5.2.3 TemperatureRangesforMicroorganisms 132
5.2.4 High-temperatureEnvironments 133
5.2.4.1 GeographyandIsolates 133
5.2.4.2 MolecularPropertiesofHyperthermophiles 136
5.2.4.3 EarlyEvolutionandHyperthermophiles 137
5.2.4.4 Applications 138
5.2.5 Low-temperatureEnvironments 138
5.2.5.1 GeographyandIsolates 138
5.2.5.2 MolecularAdaptations 139
5.2.6 BarophilesorPiezophiles 140
5.2.7 High-saltEnvironments 140
5.2.7.1 HypersalineEnvironmentsandIsolates 140
5.2.7.2 ViableHaloarchaeafromRockSalt 141
5.2.7.3 MolecularMechanisms 142
5.2.7.4 ExtraterrestrialHalite 143
5.2.8 SubterraneanEnvironments 144
5.2.9 Radiation 145
5.3 MicrobialSurvivalofExtremeConditions 146
5.4 Conclusions 148
5.5 FurtherReading 149
5.5.1 BooksorArticlesinBooks 149
5.5.2 ArticlesinJournals 149
5.5.3 WebSites 150
5.6 QuestionsforStudents 150
6 Habitability
CharlesS.Cockell
6.1 ABriefHistoryoftheAssessmentofHabitability 151
6.2 WhatDeterminesHabitability? 154
6.3 UninhabitedHabitableWorlds 156
6.4 FactorsDeterminingHabitability 156
6.4.1 HabitabilityandTemperature 156
6.4.2 HabitabilityandEnergy 160
6.4.3 OtherFactorsthatDetermineHabitability 164
TableofContents IX
6.5 APostulateforHabitability 165
6.5.1 AssumptionsabouttheHabitat 167
6.5.2 AssumptionsonLife 167
6.5.3 AttempttoFormulateaHabitabilityPostulate 167
6.6 SomeTestCasesforHabitability 169
6.6.1 TestCaseOne:LifeonVenus 169
6.6.2 TestCaseTwo:LifeontheEarlyEarth 171
6.6.3 R(cid:2)sum(cid:2)oftheTwoTestCases 173
6.7 Conclusions 173
6.8 FurtherReading 174
6.8.1 BooksandArticlesinBooks 174
6.8.2 ArticlesinJournals 174
6.9 QuestionsforStudents 176
7 AstrodynamicsandTechnologicalAspectsofAstrobiologyMissions
inOurSolarSystem
StefanosFasoulasandTinoSchmiel
7.1 Introduction 179
7.2 TheRocketEquation 180
7.2.1 Single-stagedRockets 180
7.2.2 Multiple-stagedRockets 183
7.3 OrbitalMechanicsandAstrodynamics 184
7.3.1 SomeHistoricalNotes 184
7.3.2 TheEnergyConservationEquation 187
7.3.3 SomeTypicalVelocities 188
7.4 OrbitalManeuvers 190
7.4.1 High-thrustManeuvers 190
7.4.2 Low-thrustManeuvers 192
7.4.3 Gravity-assistManeuvers 193
7.5 Example:MissionstoMars 195
7.6 FurtherReading 200
7.7 QuestionsforStudents 200
8 AstrobiologyoftheTerrestrialPlanets,withEmphasisonMars
MonicaM.Grady
8.1 TheSolarSystem 203
8.2 TerrestrialPlanets 206
8.2.1 Mercury 206
8.2.2 Venus 207
8.2.3 Earth 208
8.2.4 Mars 208
8.2.4.1 ObservingMars 208
8.2.4.2 EvidenceforWater 210
8.2.4.3 EvidenceofHeat 213
8.2.5 MeteoritesfromMars 213
X TableofContents
8.2.5.1 WhyfromMars? 213
8.2.5.2 WhatcanweLearnAboutMarsfromMartianMeteorites? 216
8.2.5.3 MicrofossilsinaMartianMeteorite? 218
8.2.6 CanWeDetectSignaturesofLifeonMars? 219
8.2.7 Conclusions:LifeBeyondEarth? 220
8.3 FurtherReading 220
8.3.1 ConcerningPlanetaryFormationandChronology 220
8.3.2 ConcerningRecentResultsfromMars 221
8.3.3 ConcerningTerrestrialandMartianMicrofossils 221
8.3.4 ConcerningMeteoritesfromMars 221
8.4 QuestionsforStudents 222
9 AstrobiologyofSaturn’sMoonTitan
FranÅoisRaulin
9.1 ExtraterrestrialBodiesofAstrobiologicalInterest 223
9.2 SomeHistoricalMilestonesintheExplorationofTitan 225
9.3 GeneralProperties,FormationandInternalStructureofTitan 226
9.3.1 MainProperties 226
9.3.2 ModelsofFormationandInternalStructure 227
9.4 AtmosphereandSurfaceofTitan 229
9.4.1 TheoreticalModelingofTitan’sAtmosphere 229
9.4.2 ExperimentalApproach 233
9.4.3 ObservationalApproach 236
9.5 AstrobiologicalAspectsofTitan 241
9.5.1 AnalogieswithPlanetEarth 241
9.5.2 OrganicChemistry 242
9.5.3 LifeonTitan? 246
9.6 Outlook:AstrobiologyandFutureExplorationofTitan 247
9.7 FurtherReading 249
9.7.1 BooksandArticlesinBooks 249
9.7.2 ArticlesinJournals 250
9.7.3 WebSites 250
9.8 QuestionsforStudents 251
10 Jupiter’sMoonEuropa:GeologyandHabitability
ChristopheSotinandDanielPrieur
10.1 AShortSurveyofthePastExplorationofEuropa 253
10.2 GeologyoftheMoonEuropa 255
10.2.1 SurfaceFeatures 255
10.2.2 CompositionoftheSurface 257
10.3 InternalStructureoftheMoonEuropa 258
10.4 ModelsofEvolutionoftheMoonEuropa 260
10.5 AstrobiologicalConsiderationsaboutPossibilitiesforLife
ontheMoonEuropa 263
10.6 SummaryandConclusions 267
TableofContents XI
10.7 OutlookandPlansforFutureMissions 268
10.8 FurtherReading 269
10.8.1 BooksandArticlesinBooks 269
10.8.2 ArticlesinJournals 270
10.8.3 WebSites 271
10.9 QuestionsforStudents 271
11 AstrobiologyExperimentsinLowEarthOrbit:Facilities,
Instrumentation,andResults
PietroBaglioni,MassimoSabbatini,andGerdaHorneck
11.1 LowEarthOrbitEnvironment,aTestBedforAstrobiology 273
11.1.1 CosmicRadiationFieldinLEO 275
11.1.1.1 GalacticCosmicRadiation 276
11.1.1.2 SolarCosmicRadiation 277
11.1.1.3 RadiationBelts 278
11.1.2 SolarExtraterrestrialUVRadiation 279
11.1.3 SpaceVacuum 280
11.1.4 TemperatureExtremes 280
11.1.5 Microgravity 281
11.2 AstrobiologyQuestionsTackledbyExperimentsinEarthOrbit 281
11.3 ExposureFacilitiesforAstrobiologyExperiments 282
11.3.1 BIOPAN 283
11.3.1.1 TechnicalCharacteristicsofBIOPAN 283
11.3.1.2 ExperimentHardwareAccommodatedwithinBIOPAN 285
11.3.1.3 OperationalAspectsofBIOPAN 288
11.3.1.4 OrbitalCharacteristicsofaBIOPANMission 291
11.3.1.5 EnvironmentofBIOPANExperiments 292
11.3.2 STONE 293
11.3.3 EXPOSE 295
11.3.3.1 EXPOSEFacility 295
11.3.3.2 EXPOSEExperiments 297
11.3.3.3 EXPOSEExperimentHardware 299
11.3.3.4 EXPOSE-RandEXPOSE-E 301
11.3.3.5 ProcessofExperimentProposal,Acceptance,Preparation,
andValidation 302
11.4 ResultsfromAstrobiologyExperimentsinEarthOrbit 303
11.4.1 RelevanceofExtraterrestrialOrganicMoleculesfortheEmergence
ofLife 304
11.4.2 RoleofSolarUVRadiationinEvolutionaryProcessesRelated
toLife 306
11.4.2.1 EfficiencyoftheStratosphericOzoneLayertoProtect
OurBiosphere 306
11.4.3 ChancesandLimitsofLifeBeingTransportedfromOneBodyof
OurSolarSystemtoAnotherorBeyond 307
11.4.3.1 EffectsofSpaceVacuum 309
XII TableofContents
11.4.3.2 EffectsofExtraterrestrialSolarUVRadiation 310
11.4.3.3 EffectsofGalacticCosmicRadiation 311
11.4.3.4 CombinedEffectsofAllParametersofSpace 313
11.4.3.5 TimeScalesofInterplanetaryTransportofLife 313
11.4.4 RadiationDosimetryinSpace 314
11.5 FutureDevelopmentandApplicationsofExposureExperiments 316
11.6 FurtherReading 317
11.6.1 BooksandArticlesinBooks 317
11.6.2 ArticlesinJournals 318
11.6.3 ESAOnlineArchives 319
11.7 QuestionsforStudents 319
12 PuttingTogetheranExobiologyMission:TheExoMarsExample
JorgeL.VagoandGerhardKminek
12.1 BackgroundoftheExoMarsMission 321
12.1.1 SearchingforLifeonMars 321
12.1.2 ExobiologyResearchatESA 322
12.1.2.1 TheESAExobiologyScienceTeamStudy 324
12.1.2.2 The1999ExobiologyAnnouncementofOpportunity 325
12.1.3 TheAURORAandtheELIPSProgramofESA 326
12.1.3.1 The2003PasteurCallforIdeas 326
12.1.3.2 ApprovaloftheExoMarsMission 328
12.2 ExoMarsScienceObjectives 328
12.2.1 SearchingforSignsofLife 328
12.2.1.1 ExtinctLife 328
12.2.1.2 ExtantLife 332
12.2.1.3 SearchforLife:Conclusions 334
12.2.2 HazardsforHumanOperationsonMars 334
12.2.3 GeophysicsMeasurements 335
12.3 ExoMarsScienceStrategy 335
12.4 ExoMarsMissionDescription 337
12.4.1 TheExoMarsRover 339
12.5 OutlookandConclusions 345
12.6 FurtherReading 346
12.6.1 BooksandArticlesinBooks 346
12.6.2 ArticlesinJournals 346
12.7 QuestionsforStudents 351
13 AstrobiologyExploratoryMissionsandPlanetaryProtectionRequirements
GerdaHorneck,Andr(cid:1)Debus,PeterMani,andJ.AndrewSpry
13.1 RationaleandHistoryofPlanetaryProtection 353
13.2 CurrentPlanetaryProtectionGuidelines 355
13.2.1 CategoryIMissions 357
13.2.2 CategoryIIMissions 357
13.2.3 CategoryIIIMissions 359