HR: 1340h
AN: P53B-1237    [Abstracts]
TI: The Conditions at Europa's Silicate-Water Interface
AU: * Sotin, C J
EM: Christophe.Sotin@jpl.nasa.gov
AF: Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, United States
AU: Grasset, O
EM: Olivier.Grasset@univ-nantes.fr
AF: Laboratoire de Planetologie et Geodynamique, 2 rue Houssiniere, Nantes, 44322, France
AU: Tobie, G
EM: Gabriel.Tobie@univ-nantes.fr
AF: Laboratoire de Planetologie et Geodynamique, 2 rue Houssiniere, Nantes, 44322, France
AU: Blanc, M
EM: Michel.Blanc@cesr.fr
AF: CESR, 9 avenue du Colonel Roche, Toulouse, 31028, France
AB: The data returned by the Galileo spacecraft strongly suggest that a liquid layer, several tens of kilometers thick, is squeezed between an outer ice shell and an inner silicate core. Compared to the other icy satellites, the relative small amount of H2O does not allow for the presence of a high-pressure ice layer between the ocean and the silicate core. The (P,T) conditions at the silicate-ocean boundary are quite similar to those existing on the Earth's sea floor where organisms live without solar energy. The study of Europa is therefore essential to answer questions such as: does life exist everywhere water is present? Can life arise and develop in an environment where there is no sunlight? Present models suggest a major difference between the Earth's sea floor and Europa's: plate tectonics allow for melting of silicates at 50 km depth and magmatic activity at mid-ocean ridges. Colonies of living species have been observed at places where the heat flux is not as high as it is at mid-ocean ridges but the heat flux is still much higher than that predicted by thermal evolution models of Europa's silicate core. One possibility would be that tidal heating resulting from Europa's eccentric orbit around Jupiter heats up the outer silicate layers resulting in volcanism similar to the one observed on Io. However, recent models (Tobie et al., JGR, 2003) suggest that most of tidal heating is dissipated in the outer icy crust and not in the silicate layer. 3D spherical models describing the thermal evolution of Europa's silicate shell are being run. These models investigate the possibility for Europa's silicate core to reach a state where tidal heating could be important and would allow for active volcanism during long periods of time. Determining the presence of an ocean and its characteristics are a major objective of the ‘LAPLACE' proposal that was submitted to the European Space Agency in response to the Cosmic Vision AO. This paper will describe the proposed payload that will acquire the data necessary to answer the questions described above.
DE: 0930 Oceanic structures
DE: 1241 Satellite geodesy: technical issues (6994, 7969)
DE: 5220 Hydrothermal systems and weathering on other planets
DE: 6063 Volcanism (5480, 8450)
DE: 6221 Europa
SC: Planetary Sciences [P]
MN: 2007 Fall Meeting