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J.A. Stansberry (University of Arizona, Tucson), D.R. Davis (Planetary Sci. Inst., Tucson)
The Kuiper Belt is hypothesized to be a reservoir of relatively pristine objects who's chemical makeup is closely linked to the composition of the primordial trans-Neptunian planetary nebula. This view is supported by observations of CO-driven cometary activity in a few bodies likely to have been recently extracted from the KBO population (Chiron, Hale-Bopp, SW-1).
Impacts between objects in the Kuiper Belt can produce deep/global fracture systems. The rate of shattering collisions in the belt is significant. 200km diameter KBOs should have experienced roughly 10 shattering (but not disruptive) collisions over the past 4Gy. Lesser impacts will produce outer megaregolith layers on all of the large KBOs. At the internal temperatures expected for KBOs such fracture systems will persist for the age of the solar system in all but the deepest layers of the very largest known KBOs.
The presence of open fissures penetrating well into KBOs may lead to significant devolatilization of their interiors, and has implications for the nature of short-period comet nuclei and the (as yet unmeasured) rate of occurrence of super-volatile driven cometary activity in distant comets and Centaurs.