Book contents
- Frontmatter
- Contents
- List of contributors
- Part I Introduction
- Part II Origin of Planets and Life
- Part III History of Life on Earth
- Part IV Habitability of the Solar System
- 8 Early Mars – Cradle or Cauldron?
- 9 Large Habitable Moons
- 10 Small Habitable Worlds
- Part V Exoplanets and Life in the Galaxy
- Index
- Plate Section
- References
9 - Large Habitable Moons
Titan and Europa
from Part IV - Habitability of the Solar System
Published online by Cambridge University Press: 05 December 2012
Book contents
- Frontmatter
- Contents
- List of contributors
- Part I Introduction
- Part II Origin of Planets and Life
- Part III History of Life on Earth
- Part IV Habitability of the Solar System
- 8 Early Mars – Cradle or Cauldron?
- 9 Large Habitable Moons
- 10 Small Habitable Worlds
- Part V Exoplanets and Life in the Galaxy
- Index
- Plate Section
- References
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Summary
Introduction
The “classical” criteria for habitability can be summarized as the presence of liquid water, energy sources to sustain metabolism, and “nutrients” over a period of time long enough to allow the development of life. The concept of a “habitable zone” (HZ) around each star defines where water can be stable at the surface as a result of the equilibrium temperature of the planet in the star's radiation field. Liquid water may exist on the surface of planets orbiting a star at a distance that does not induce tidal lock. But habitability conditions can be found not only on the surfaces of Earth-like planets: a subsurface ocean within a planet or the satellite of a gas giant may be habitable for some life form that may be very different from Earth-like life. Indeed, icy surfaces may cover liquid oceans, move and fracture like plate tectonics, and exsolute the internal material and energy through an interconnected system. With the discovery of planets beyond the Solar System and the search for life in exotic habitats such as Mars, Europa, Titan, and Enceladus, habitability in general needs a better and broader definition.
Liquid water has been recognized as the best solvent for life to emerge and evolve, although other possibilities have been suggested (e.g. Bains 2004). Water, an abundant compound in our galaxy (e.g. Cernicharo and Crovisier 2005), is liquid within a large range of temperatures and pressures and is also a strong polar–nonpolar solvent. This dichotomy is essential for maintaining stable biomolecular and cellular structures (Des Marais et al. 2002). A large number of organisms is capable of living in water. However, in a body of pure water, life will probably never spontaneously originate and evolve. This is because, while there are many organisms living in water, none we know of is capable of living on water alone because life requires other essential elements such as nitrogen and phosphorus in addition to hydrogen and oxygen. Besides, no organism we know of is made entirely of water. So obviously “just water” is not an auspicious place for starting life and evolution in.
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- Frontiers of Astrobiology , pp. 175 - 200Publisher: Cambridge University PressPrint publication year: 2012
References
2004 Many chemistries could be used to build living systemsAstrobiology 4 137CrossRefGoogle ScholarPubMed
2009 New insights on Titan's plasma-driven Schumann resonance inferred from Huygens and Cassini DataPlanetary and Space Science 57 1872CrossRefGoogle Scholar
2009 LAPLACE: a mission to Europa and the Jupiter system for ESA's cosmic vision programmeExperimental Astronomy 23 849CrossRefGoogle Scholar
2008 The identification of liquid ethane in Titan's Ontario LacusNature 454 607CrossRefGoogle ScholarPubMed
2009 73 173
2009
2010 115
2007 The composition of Titan's stratosphere from Cassini/CIRS mid-infrared spectraIcarus 189 35CrossRefGoogle Scholar
2010 Titan trace gaseous composition from CIRS at the end of the Cassini-Huygens prime missionIcarus 207 461Google Scholar
2010 68
2010 The photochemical products of benzene in Titan's upper atmosphereIcarus 207 477CrossRefGoogle Scholar
2002 Remote sensing of planetary properties and biosignatures on extrasolar terrestrial planetsAstrobiology 2 153CrossRefGoogle ScholarPubMed
2009 Reduction in haze formation rate on prebiotic Earth in the presence of hydrogenAstrobiology 9 447CrossRefGoogle ScholarPubMed
2005 Titan's atmospheric temperatures, winds, and compositionScience 308 975CrossRefGoogle ScholarPubMed
2000 Exobiological implications of a possible ammonia–water ocean inside TitanIcarus 146 444CrossRefGoogle Scholar
2007 Ammonium sulfate on Titan: possible origin and role in cryovolcanismIcarus 188 139CrossRefGoogle Scholar
2005 In situ measurements of the physical characteristics of Titan's environmentNature 438 785CrossRefGoogle ScholarPubMed
2009 Astrobiology and the potential for life on EuropaEuropaTucsonUniversity of Arizona Press589Google Scholar
2008 Hydrocarbon lakes on Titan: distribution and interaction with a porous regolithGeophysical Research Letters 35 09204CrossRefGoogle Scholar
2005 Complex organic matter in Titan's atmospheric aerosols from in situ pyrolysis and analysisNature 438 796CrossRefGoogle ScholarPubMed
1996 A large deep freshwater lake beneath the ice of Central East AntarcticaNature 381 684CrossRefGoogle Scholar
2006 Atmospheric composition and climate on the early EarthPhilosophical Transactions of the Royal Society, Series B: Biological Sciences 361 1733CrossRefGoogle ScholarPubMed
1999 Europa and Callisto: induced or intrinsic fields in a periodically varying plasma environmentJournal of Geophysical Research 104 4609CrossRefGoogle Scholar
2008 Titan's inventory of organic surface materialsGeophysical Research Letters 35 02206CrossRefGoogle Scholar
2008 Titan's rotation reveals an internal ocean and changing zonal windsScience 319 1649CrossRefGoogle ScholarPubMed
2005 Possibilities for methanogenic life in liquid methane on the surface of TitanIcarus 178 274CrossRefGoogle Scholar
1999 Analytic solutions for the antigreenhouse effect: Titan and the early EarthIcarus 137 56CrossRefGoogle Scholar
2008 Synthesis of polycyclic aromatic hydrocarbons and acetylene polymers in ice: a prebiotic scenarioChemistry and Biodiversity 5 2729CrossRefGoogle ScholarPubMed
2007 Carbon isotopic enrichment in Titan's tholins? Implications for Titan's aerosolsPlanetary and Space Science 55 2010CrossRefGoogle Scholar
2005 The abundances of constituents of Titan's atmosphere from the GCMS instrument on the Huygens probeNature 438 779CrossRefGoogle ScholarPubMed
2000 Greenhouse warming by CH4 in the atmosphere of early EarthJournal of Geophysical Research 105 11981CrossRefGoogle ScholarPubMed
2011 A salt-water reservoir as the source of a compositionally stratified plume on EnceladusNature 474 620CrossRefGoogle ScholarPubMed
2008
2007 Outgassing of ordinary chondritic material and some of its implications for the chemistry of asteroids, planets, and satellitesIcarus 186 462CrossRefGoogle Scholar
2010 Search for habitable planetsAstrobiology: Emergence, Search and Detection of LifeAmerican Scientific PublishersGoogle Scholar
2007 Could we identify hot ocean-planets with CoRoT, Kepler and Doppler velocimetry?Icarus 191 453CrossRefGoogle Scholar
2000 BristolInstitute of Physics Publishing1823
2010 Molecular hydrogen in Titan's atmosphere: implications of the measured tropospheric and thermospheric mole fractionsIcarus 208 878CrossRefGoogle Scholar
2005 Titan's internal structure inferred from a coupled thermal-orbital modelIcarus 175 496CrossRefGoogle Scholar
2005 Rain, winds and haze during the Huygens probe's descent to Titan's surfaceNature 438 765CrossRefGoogle ScholarPubMed
2006 Organic haze on Titan and the early EarthProceedings of the National Academy of Sciences 103 18035CrossRefGoogle ScholarPubMed
2005 Ice and the origin of lifeOrigins of Life and Evolution of Biospheres 35 429CrossRefGoogle ScholarPubMed
2006 Journal of Geophysical Research 111
2007 The process of tholin formation in Titan's upper atmosphereScience 316 870CrossRefGoogle ScholarPubMed
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