The Astronomy and Astrophysics Review

, Volume 17, Issue 2, pp 181–249

What makes a planet habitable?

  • H. Lammer
  • J. H. Bredehöft
  • A. Coustenis
  • M. L. Khodachenko
  • L. Kaltenegger
  • O. Grasset
  • D. Prieur
  • F. Raulin
  • P. Ehrenfreund
  • M. Yamauchi
  • J.-E. Wahlund
  • J.-M. Grießmeier
  • G. Stangl
  • C. S. Cockell
  • Yu. N. Kulikov
  • J. L. Grenfell
  • H. Rauer
Review Article

Abstract

This work reviews factors which are important for the evolution of habitable Earth-like planets such as the effects of the host star dependent radiation and particle fluxes on the evolution of atmospheres and initial water inventories. We discuss the geodynamical and geophysical environments which are necessary for planets where plate tectonics remain active over geological time scales and for planets which evolve to one-plate planets. The discoveries of methane–ethane surface lakes on Saturn’s large moon Titan, subsurface water oceans or reservoirs inside the moons of Solar System gas giants such as Europa, Ganymede, Titan and Enceladus and more than 335 exoplanets, indicate that the classical definition of the habitable zone concept neglects more exotic habitats and may fail to be adequate for stars which are different from our Sun. A classification of four habitat types is proposed. Class I habitats represent bodies on which stellar and geophysical conditions allow Earth-analog planets to evolve so that complex multi-cellular life forms may originate. Class II habitats includes bodies on which life may evolve but due to stellar and geophysical conditions that are different from the class I habitats, the planets rather evolve toward Venus- or Mars-type worlds where complex life-forms may not develop. Class III habitats are planetary bodies where subsurface water oceans exist which interact directly with a silicate-rich core, while class IV habitats have liquid water layers between two ice layers, or liquids above ice. Furthermore, we discuss from the present viewpoint how life may have originated on early Earth, the possibilities that life may evolve on such Earth-like bodies and how future space missions may discover manifestations of extraterrestrial life.

Keywords

Habitability Origin of life Terrestrial planets Subsurface oceans Atmosphere evolution Earth-like exoplanets Space weather Astrobiology 

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Copyright information

© Springer-Verlag 2009

Authors and Affiliations

  • H. Lammer
    • 1
  • J. H. Bredehöft
    • 2
  • A. Coustenis
    • 3
  • M. L. Khodachenko
    • 1
  • L. Kaltenegger
    • 4
  • O. Grasset
    • 5
  • D. Prieur
    • 6
  • F. Raulin
    • 7
  • P. Ehrenfreund
    • 8
  • M. Yamauchi
    • 9
  • J.-E. Wahlund
    • 10
  • J.-M. Grießmeier
    • 11
  • G. Stangl
    • 1
  • C. S. Cockell
    • 12
  • Yu. N. Kulikov
    • 13
  • J. L. Grenfell
    • 14
    • 15
  • H. Rauer
    • 15
  1. 1.Space Research InstituteAustrian Academy of SciencesGrazAustria
  2. 2.Institut für Angewandte und Physikalische ChemieUniversität BremenBremenGermany
  3. 3.Laboratoire d’Etudes Spatiales et d’Instrumentation en Astrophysique (LESIA), Observatoire de MeudonMeudonFrance
  4. 4.Harvard-Smithonian Center for AstrophysicsCambridgeUSA
  5. 5.UMR, Laboratoire de Planétologie et GéodynamiqueNantesFrance
  6. 6.Laboratoire de Microbiologie des Environnements ExtrêmesUniversité de Bretagne OccidentaleBrestFrance
  7. 7.Laboratoire Interuniversitaire des Systèmes Atmopshériques, CNRS & Universités Paris 12 et Paris 7CréteilFrance
  8. 8.Astrobiology Group Leiden Institute of ChemistryUniversity of LeidenLeidenThe Netherlands
  9. 9.Swedish Institute for Space PhysicsKirunaSweden
  10. 10.Swedish Institute for Space PhysicsUppsalaSweden
  11. 11.ASTRONDwingelooThe Netherlands
  12. 12.CEPSAR, Open UniversityMilton KeynesUK
  13. 13.Polar Geophysical InstituteRussian Academy of SciencesMurmanskRussian Federation
  14. 14.Zentrum für Astronomie und AstrophysikTechnische Universität BerlinBerlinGermany
  15. 15.Deutsches Zentrum für Luft- und RaumfahrtInstitut für PlanetenforschungBerlinGermany

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