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The origin of water on Mars |
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| Authors: | Jonathan I Lunine John Chambers Alessandro Morbidelli |
| Institution: | a Lunar and Planetary Laboratory, The University of Arizona, Tucson, AZ 85721, USA b SETI Institute, Mountain View, CA 94043, USA c NASA Ames Research Center, Mountain View, CA 94035, USA d Observatoire de la Côte d'Azur, BP 4229, F-06304 Nice cedex 4, France e Department of Geological Sciences, Arizona State University, Tempe, AZ 85287, USA |
| Abstract: | This paper considers the origin of water on Mars, in the context of a dynamical model that accounts for most of the Earth's water as a product of collisions between the growing Earth and planet-sized “embryos” from the asteroid belt. Mars' history is found to be different; to explain the present mass of Mars requires that it suffer essentially no giant collisions and the bulk of its growth is through addition of smaller bodies. Asteroids and comets from beyond 2.5 AU provide the source of Mars' water, which totals 6-27% of the Earth's present ocean (1 Earth ocean≡1.5×1021 kg), equivalent to 600-2700-m depth on the martian surface. The D/H ratio of this material is 1.2-1.6 times Standard Mean Ocean Water, the smaller value obtaining for the larger amount of water accreted. The upper half of the range of total water accreted, while many times less than that acquired by the Earth, is consistent with geological data on Mars, and the D/H value is that derived for martian magmatic water from SNC meteorites. Both together are consistent with published interpretations of the high D/H in present-day martian atmospheric water in terms of water loss through atmospheric escape. |
| Keywords: | Origin Solar System Mars interior Mars atmosphere Planetesimals |
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