Collisional Processing of Olivine and Pyroxene in Cometary DustAccording to the nebular theory of solar-system formation, collisions between bodies occurred frequently early in the solar system s history and continue at a lower rate even today. Collisions have reworked the surface compositions and structures of cometary nuclei, though to an unknown degree. The majority of the collisional history of a typical Jupiter-family comet takes place while it resides in the Kuiper Belt. Impacts occur on the surfaces of small bodies over a large range of velocities by impactors of all sizes, but typical encounter speeds within the Kuiper Belt are 1.5 to 2.0 km/s[1]. Durda and Stern suggest that the interiors of most cometary nuclei with diameters <5 km have been heavily damaged by collisions [2]. They estimate that over a period of 3.5 Gy, a nucleus with a diameter of 2 km and an orbit between 35-45 AU will experience 90-300 collisions with objects greater than 8 m in diameter. In this same time interval, collisions between a typical Trans-Neptunian Object (TNO) 200 km in diameter and objects with d > 8 m would rework up to one-third of that TNO s surface. In fact, it has been proposed that most short-period comets from the Kuiper Belt (90%) are collisional fragments from larger TNOs - not primordial objects themselves [3] - and that most short-period comets from the Kuiper Belt will be collisionally processed both on their surfaces as well as in their interiors.
Document ID
20080009611
Acquisition Source
Johnson Space Center
Document Type
Conference Paper
Authors
Lederer, S. M. (California State Univ. San Bernardino, CA, United States)
Cintala, M. J. (NASA Johnson Space Center Houston, TX, United States)
Olney, R. D. (California State Univ. San Bernardino, CA, United States)
Keller, L. P. (NASA Johnson Space Center Houston, TX, United States)
Nakamura-Messenger, K. (Jacobs Engineering Group, Inc. Houston, TX, United States)
Zolensky, M. (NASA Johnson Space Center Houston, TX, United States)