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A. R. Dobrovolskis (UC Santa Cruz/NASA Ames), J. L. Alvarellos (Space Systems Loral), J. J. Lissauer (NASA Ames Research Center)
Small bodies left over from the formation of the planets and satellites litter the Solar System, along with the debris from more recent collisions. These bodies are removed by expulsion from heliocentric or planetocentric orbit, as well as by collisions with planets, moons, and the Sun, with characteristic lifetimes depending on their orbits. However, the rate at which a given population of objects declines cannot be described by the simple exponential law used to describe radioactive decay. On the contrary, the removal of comets and remnant planetesimals has sometimes been described as ``logarithmic decay". Our work on the fate of ejecta from Hyperion (Dobrovolskis and Lissauer 2004, Icarus 169, 462-473) as well as our recent results from other satellites suggests instead that ejecta removal is best described by a ``stretched exponential" decay law, where the particle lifetimes increase as a fractional power of the elapsed time, suggestive of a diffusion process. Statistical analysis suports this conclusion, and enables us to determine the decay parameters. The results should be valuable in several contexts, including the delivery of meteorites to Earth and the bombardment history of the planets and their moons.
NASA's PGG grant RTOP 344-30-50-01 supported this research.
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Bulletin of the American Astronomical Society, 37 #3
© 2004. The American Astronomical Soceity.