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Explosive erosion during the Phoenix landing exposes subsurface water on Mars |
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| Authors: | Manish Mehta Nilton O. Renno John Marshall Anita Sengupta Jasper F. Kok Raymond E. Arvidson Mark T. Lemmon |
| Affiliation: | a Dept. of Atmospheric, Oceanic and Space Sciences, University of Michigan, 2455 Hayward St., Ann Arbor, MI 48109, USA b Applied Physics Program, University of Michigan, Ann Arbor, MI 48109, USA c Carl Sagan Center, SETI Institute, Mountain View, CA 94043, USA d NASA Jet Propulsion Laboratory, Section 313, Pasadena, CA 91109, USA e Dept. of Earth and Planetary Sciences, Washington University in St. Louis, St. Louis, MO 63130, USA f Max Planck Institute for Solar System Research, Max-Planck-Str. 2, Katlenburg-Lindau 37191, Germany g Dept. of Atmospheric Sciences, Texas A&M University, College Station, TX 77843, USA h Dept. of Planetary Sciences, University of Arizona, Tucson, AZ 85721, USA i Advanced Studies Program, National Center for Atmospheric Research Boulder, CO 80305, USA |
| Abstract: | While steady thruster jets caused only modest surface erosion during previous spacecraft landings on the Moon and Mars, the pulsed jets from the Phoenix spacecraft led to extensive alteration of its landing site on the martian arctic, exposed a large fraction of the subsurface water ice under the lander, and led to the discovery of evidence for liquid saline water on Mars. Here we report the discovery of the ‘explosive erosion’ process that led to this extensive erosion. We show that the impingement of supersonic pulsed jets fluidizes porous soils and forms cyclic shock waves which propagate through the soil and produce erosion rates more than an order of magnitude larger than that of other jet-induced processes. The understanding of ‘explosive erosion’ allows the calculation of bulk physical properties of the soils altered by it, provides insight into a new behavior of granular flow at extreme conditions and explains the rapid alteration of the Phoenix landing site’s ground morphology at the northern arctic plains of Mars. |
| Keywords: | Ices Cratering |
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