Astrobiology is defined as the study of the origin, evolution, distribution, and future of life in the universe (NASA’s definition; Des Marais et al. 2008). Astrobiology seeks to answer fundamental questions about the beginning and...
moreAstrobiology is defined as the study of the origin, evolution,
distribution, and future of life in the universe (NASA’s definition;
Des Marais et al. 2008). Astrobiology seeks to answer
fundamental questions about the beginning and evolution of
life on Earth, possible existence of extraterrestrial life, and
the future of life on Earth and beyond. Astrobiology scope is
delineated in the NASA’s astrobiology roadmap (Des Marais
et al. 2008). Specific goals include understanding the emergence
of life on Earth, determining how the early life on
Earth interacted and evolved with its changing environment,
understanding the evolutionary mechanisms and environmental
limits of life, exploring habitable environments in our solar
system and searching for life, understanding the nature and
distribution of habitable environments in the universe, and
recognizing signatures of life on the early Earth and on other
worlds. The NASA’s astrobiology map is being updated as
the astrobiology field advances. A similar roadmap has been
developed for astrobiology research in Europe (Horneck et al.
2015, 2016). The topic of these roadmaps is further discussed
and updated in Section 1 of this handbook.
Astrobiology is a young science that acquired its name
only in 1995 (named by Wes Huntress from NASA; Catling
2013). Astrobiology evolved from its predecessor, exobiology,
which is the study of the origin of life and of possible
life outside Earth (Dick and Strick 2004; Dick 2007). The
term exobiology was coined in 1960 (by Joshua Lederberg).
The difference between the two fields is that astrobiology is
broader and notably includes the evolution of life on Earth.
The exobiology era coincided with the space missions, notably
the Viking mission on Mars in 1976, which followed a
series of reconnaissance missions in the 1960s and early
1970s.
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Table.of.Contents
Preface......Page.12
Editor......Page.14
Contributors......Page.16
SECTION.I:.Astrobiology:.Definition,.Scope,.and.Education......Page.22
Chapter.1.1.Astrobiology:.Definition,.Scope,.and.a.Brief.Overview......Page.24
Chapter.1.2.Astrobiology.Goals:.NASA.Strategy.and.European.Roadmap......Page.36
Chapter.1.3.Online,.Classroom.and.Wilderness.Teaching.Environments:.Reaching.Astrobiology.Learners.of.All.Ages.Around.the.World......Page.48
Chapter.1.4.Astrobiology.as.a.Medium.of.Science.Education......Page.66
Chapter.1.5.Astrobiology-as-Origins-Story:.Education.and.Inspiration.across.Cultures......Page.70
SECTION.II:.Definition.and.Nature.Of.Life......Page.76
Chapter.2.1.Defining.Life:.Multiple.Perspectives......Page.78
Chapter.2.2.A.Generalized.and.Universalized.Definition.of.Life.Applicable.to.Extraterrestrial.Environments......Page.86
Chapter.2.3.Synthetic.Cells.and.Minimal.Life......Page.96
Chapter.2.4.Communication.as.the.Main.Characteristic.of.Life......Page.112
SECTION.III:.Origin.of.Life:.History,.Philosophical.Aspects,.and.Major.Developments......Page.128
Chapter.3.1.Philosophical.Aspects.of.the.Origin-of-Life.Problem:.Neither.by.Chance.Nor.by.Design.....Page.130
Chapter.3.2.Charles.Darwin.and.the.Plurality.of.Worlds:.Are.We.Alone?......Page.146
Chapter.3.3.An.Early.History.from.Buffon.to.Oparin......Page.158
SECTION.IV:.Chemical.Origins.of.Life:.Chemicals.in.the.Universe.and.Their.Delivery.on.the.Early.Earth;.Geology.and.Atmosphere.on.the.Early.Earth......Page.166
Chapter.4.1.Interstellar.Molecules.and.Their.Prebiotic.Potential......Page.168
Chapter.4.2.Formation.and.Delivery.of.Complex.Organic.Molecules.to.the.Solar.System.and.Early.Earth.....Page.186
Chapter.4.3.Organic.Molecules.in.Meteorites.and.Their.Astrobiological.Significance.....Page.198
Chapter.4.4.Ancient.Life.and.Plate.Tectonics......Page.216
Chapter.4.5.Atmosphere.on.Early.Earth.and.Its.Evolution.as.It.Impacted.Life......Page.228
SECTION.V:.Chemical.Origin.of.Life:.Prebiotic.Chemistry......Page.238
Chapter.5.1.Prebiotic.Chemistry.That.Led.to.Life.....Page.240
Chapter.5.2.Prebiotic.Chemical.Pathways.to.RNA.and.the.Importance.of.Its.Compartmentation......Page.256
Chapter.5.3.The.Hydrothermal.Impact.Crater.Lakes:.The.Crucibles.of.Life’s.Origin......Page.286
Chapter.5.4.Prebiotic.Chemistry.in.Hydrothermal.Vent.Systems......Page.318
Chapter.5.5.Prebiotic.Reactions.in.Water,.“On.Water,”.in.Superheated.Water,.Solventless,.and.in.the.Solid.State......Page.352
Chapter.5.6.The.Origin.and.Amplification.of.Chirality.Leading.to.Biological.Homochirality......Page.362
Chapter.5.7.Phosphorus.in.Prebiotic.Chemistry—An.Update.and.a.Note.on.Plausibility......Page.376
Chapter.5.8.Phosphorylation.on.the.Early.Earth:.The.Role.of.Phosphorus.in.Biochemistry.and.Its.Bioavailability......Page.382
Chapter.5.9.Silicon.and.Life......Page.392
SECTION.VI:.RNA.and.RNA.World:.Complexity.of.Life’s.Origins......Page.398
Chapter.6.1.Transitions:.RNA.and.Ribozymes.in.the.Development.of.Life......Page.400
Chapter.6.2.Three.Ways.to.Make.an.RNA.Sequence:.Steps.from.Chemistry.to.the.RNA.World......Page.416
Chapter.6.3.Coevolution.of.RNA.and.Peptides......Page.430
Chapter.6.4.Role.of.Cations.in.RNA.Folding.and.Function.....Page.442
Chapter.6.5.The.Origin.of.Life.as.an.Evolutionary.Process:.Representative.Case.Studies......Page.458
Chapter.6.6.The.Complexity.of.Life’s.Origins:.A.Physicochemical.View.....Page.484
SECTION.VII:.Origin.of.Life:.Early.Compartmentalization—Coacervates.and.Protocells......Page.502
Chapter.7.1.Oparin’s.Coacervates......Page.504
Chapter.7.2.Protocell.Emergence.and.Evolution......Page.512
SECTION.VIII:.Origin.of.Life.and.Its.Diversification..Universal.Tree.of.Life..Early.Primitive.Life.on.Earth..Fossils.of.Ancient.Microorganisms..Biomarkers.and.Detection.of.Life......Page.540
Chapter.8.1.The.Progenote,.Last.Universal.Common.Ancestor,.and.the.Root.of.the.Cellular.Tree.of.Life......Page.542
Chapter.8.2.Horizontal.Gene.Transfer.in.Microbial.Evolution.....Page.548
Chapter.8.3.Viruses.in.the.Origin.of.Life.and.Its.Subsequent.Diversification.....Page.556
Chapter.8.4.Carl.R..Woese.and.the.Journey.toward.a.Universal.Tree.of.Life.....Page.576
Chapter.8.5.Fossils.of.Ancient.Microorganisms...Page.588
Chapter.8.6.Biomarkers.and.Their.Raman.Spectral.Signatures:.An.Analytical.Challenge.in.Astrobiology...Page.618
Chapter.8.7.Fossilization.of.Bacteria.and.Implications.for.the.Search.for.Early.Life.on.Earth.and.Astrobiology.Missions.to.Mars......Page.630
SECTION.IX:.Life.under.Extreme.Conditions—Microbes.in.Space......Page.654
Chapter.9.1.Extremophiles.and.Their.Natural.Niches.on.Earth......Page.656
Chapter.9.2.Microbes.in.Space......Page.682
Chapter.9.3.Virus.Evolution.and.Ecology:.Role.of.Viruses.in.Adaptation.of.Life.to.Extreme.Environments......Page.698
SECTION.X:.Habitability:.Characteristics.of.Habitable.Planets.....Page.704
Chapter.10.1.The.Evolution.of.Habitability:.Characteristics.of.Habitable.Planets......Page.706
SECTION.XI:.Intelligent.Life.in.Space:.History,.Philosophy,.and.SETI.(Search.for.Extraterrestrial.Intelligence)......Page.720
Chapter.11.1.Mind.in.Universe:.On.the.Origin,.Evolution,.and.Distribution.of.Intelligent.Life.in.Space.....Page.722
Chapter.11.2.Where.Are.They?.Implications.of.the.Drake.Equation.and.the.Fermi.Paradox......Page.738
Chapter.11.3.SETI:.Its.Goals.and.Accomplishments......Page.748
Chapter.11.4.Humanistic.Implications.of.Discovering.Life.Beyond.Earth......Page.762
SECTION.XII:.Exoplanets,.Exploration.of.Solar.System,.the.Search.for.Extraterrestrial.Life.in.Our.Solar.System,.and.Planetary.Protection......Page.778
Chapter.12.1.Exoplanets:.Methods.for.Their.Detection.and.Their.Habitability.Potential......Page.780
Chapter.12.2.Solar.System.Exploration:.Small.Bodies.and.Their.Chemical.and.Physical.Conditions......Page.796
Chapter.12.3.Solar.System.Exploration:.Icy.Moons.and.Their.Habitability......Page.808
Chapter.12.4.Searching.for.Extraterrestrial.Life.in.Our.Solar.System......Page.822
Chapter.12.5.Planetary.Protection.....Page.840
Index......Page.856