Europa: The Prospects for an Ocean
Tidal dissipation in the satellites of a giant planet may provide sufficient heating to maintain a liquid water ocean below a thin ice layer. In our own solar system, Europa, one of the Galilean satellites of Jupiter, may have such an ocean. Both theoretical calculations and certain observations support its existence, although proof is lacking. The putative ocean would probably have temperatures, pressures, and chemistry conducive to biologic activity. However, the environment would be severely energy limited. Possible energy sources include transient transmission of sunlight through fractures in the ice and hydrothermal activity on the ocean floor. While temporary conditions could exist that are within the range of adaptation of certain terrestrial organisms, origin of life under such conditions seems unlikely. In other solar systems, however, larger satellites with more significant heat flow could provide environments that are stable over an order of aeons and in which life could perhaps evolve.
KeywordsSolar System Giant Planet Habitable Zone Galilean Satellite Outer Solar System
Unable to display preview. Download preview PDF.
- 1.Huang, S., Occurrence of life in the universe, American Scientist 47, 397–402 (1959).Google Scholar
- 3.Cassen, P.M., S.J. Peale, and R.T. Reynolds, Structure and thermal evolution of the Galilean satellites, The satellites of Jupiter (D. Morrison, Ed.) U. of Arizona Press, 93–128 (1982).Google Scholar
- 7.Smith, B.A., L.A. Soderblom, R. Beebe, D. Bliss, J.M. Boyce, A. Brahic, G.A. Briggs, R.H. Brown, S.A. Collins, A.F. Cook II, S.K. Croft, J.N. Cuzzi, G.E. Danielson, M.E. Davies, T.E. Dowling, D. Godfrey, C.J. Hansen, C. Harris, G.E. Hunt, A.P. Ingersoll, T.V. Johnson, R.J. Krauss, H. Masursky, D. Morrison, T. Owen, J.B. Plescia, J.B. Pollack, C.C. Porco, K. Rages, C. Sagan, E.M. Shoemaker, L.A. Sromovsky, C. Stoker, R.G. Strom, V.E. Suomi, S.P. Synnott, R.J. Terrile, P. Thomas, W.R. Thompson, and J. Veverka, Voyager 2 in the Uranian System: Imaging Science Results, Science 233, 43–64 (1986).ADSCrossRefGoogle Scholar
- 18.Ojakangas, G.W., and Stevenson, D.J., in preparation.Google Scholar
- 24.Sullivan, C.W., and A.C. Palmisano, Sea-ice microbial communities in McMurdo Sound, Antarctic J. U.S. 16(5), 126–127 (1981).Google Scholar
- 28.Kasting, J.F., and T.P. Ackerman, Climatic consequences of very high C02 levels in Earth’s early atmosphere, Science submitted (1986).Google Scholar