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EP: Fachverband Extraterrestrische Physik

EP 11: Planets and Small Bodies II

EP 11.1: Invited Talk

Thursday, April 2, 2009, 13:00–13:30, HS-Ost Pharmazie

Planetary Evolution and Habitability — •Tilman Spohn — DLR Institute of Planetary Research, Berlin, Germany

The search for extraterrestrial life is a most outstanding task assumed by the international space community. Finding extraterrestrial life will complete the Copernican and Darwinian revolutions and put human existence into perspective. The search for extraterrestrial life rests on research to understand and predict is whereabouts. Planetary science can contribute by studying the ability of planets to host life, their habitability and include life as a biogeochemical process into evolution modeling. A research alliance to study planetary evolution and life has been formed lead by DLR and sponsored by the Helmholtz Association. Planetary habitability is thought to require water on (or near) the surface, a magnetic field to protect against cosmic radiation, and transport mechanisms for nutrients. The stability of liquid water on the surface of the terrestrial defines a narrow habitable zone in our solar system but the zone may be much wider as life may exist in oceans underneath ice covers in satellites and, more general, ocean planets. A magnetic field also serves to protect an existing atmosphere against erosion by the solar wind and thus helps to stabilize the presence of water. Magnetic fields are generated in the cores of the terrestrial planets and thus habitability is linked to the evolution of the interior. The latter is a potential source and sink for water interacting with the surface and atmosphere reservoirs through volcanism and recycling. The most efficient known recycling mechanism is plate tectonics. Is plate tectonics even a potential biosignature?