THE IMPACTOR FLUX IN THE PLUTO-CHARON SYSTEM

Current impact rates of comets on Pluto and Charon are estimated. It is shown that the dominant sources of impactors are comets from the Kuiper belt and the inner Oort cloud, each of whose perihelion distributions extends across Pluto's orbit. In contrast, long-period comets from the outer Oort cloud are a negligible source of impactors. The total predicted number of craters is not sufficient to saturate the surface areas of either Pluto or Charon over the age of the Solar System. However, heavy cratering may have occurred early in the Solar System's history during clearing of planetesimals from the outer planets' zone. (C) 1994 Academic Press, Inc.