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J.L. Alvarellos (Space Systems/Loral), A.R. Dobrovolskis (UCO/Lick Observatory, UC Santa Cruz), K.J. Zahnle (NASA Ames Research Center)
We have followed the orbital evolution of escaped impact debris (modeled as massless test particles) from Saturnian satellites using the Swift package of Levison and Duncan (1994). The ejecta are assumed to originate in the impact events that produced the giant craters on Mimas and Tethys. The initial conditions for the particles are consistent with what is currently known about cratering physics. We conjecture that if the surfaces of these satellites are "loose" like regolith, then the initial velocities of the impact debris should follow the gravity-scaling model of Housen et al. (1983). In contrast, if the surfaces have inherent strength like hard ice, then the velocities of the particles should follow the spallation model of Melosh (1984). For each crater, 600 particles were ejected following the gravity-scaling model, and 600 particles were ejected following the spallation model. By running both models we hope to bracket the actual behavior of the impact ejecta. Most escaped debris re-accretes rather quickly on the source moon, but some particles reach other satellites. Issues we will discuss are the expected sizes of the ejecta blocks and of the craters they would make upon re-accretion. It is hoped that these investigations could shed some light in the current debate over cratering populations in the outer solar system.
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Bulletin of the American Astronomical Society, 35 #4
© 2003. The American Astronomical Soceity.