HR: 09:45h
AN: P51E-08    [Abstracts]
TI: Impact Gardening on Europa
AU: * Phillips, C B
EM: phillips@seti.org
AF: Carl Sagan Center SETI Institute, 515 N. Whisman Rd., Mountain View, CA 94043,
AU: Grossman, L
EM: lig5@cornell.edu
AF: Carl Sagan Center SETI Institute, 515 N. Whisman Rd., Mountain View, CA 94043,
AU: Grossman, L
EM: lig5@cornell.edu
AF: Department of Astronomy, Cornell University, Ithaca, NY 14853,
AB: Charged-particle interactions with materials at Europa's surface can produce useful oxidants and simple organics. These oxidants and organics, if transported downward through the ice shell to a liquid water layer, could provide a significant amount of energy to sustain a biosphere. However, irradiation also destroys such materials if they remain exposed on Europa's surface. Sputtering erosion and surface mixing through impact gardening act to change the preservation depth. If sputtering dominates over gardening, then material is created and destroyed at Europa's surface much faster than it can be buried and preserved by gardening. However, if gardening dominates, this means that irradiation products can be buried beneath the surface by gardening, where they are protected from further radiation processing. We present new results on the gardening depth on Europa based on extrapolations from counts of small craters and models of regolith growth based on studies of the moon. The problem is complicated by the fact that most small craters on Europa are likely secondaries. Our new results suggest that the gardening depth on Europa is about 1 cm. This result means that sputtering likely dominates over gardening under most circumstances. CBP was supported by the NAI, and LG was supported by the NSF REU program.
DE: 5220 Hydrothermal systems and weathering on other planets
DE: 5415 Erosion and weathering
DE: 5420 Impact phenomena, cratering (6022, 8136)
DE: 5470 Surface materials and properties
DE: 6221 Europa
SC: Planetary Sciences [P]
MN: 2007 Fall Meeting