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D. G. Korycansky, E. Asphaug (CODEP/IGPP UC Santa Cruz)
We present results of modeling rubble-pile asteroids as collections of polyhedra. We solve the equations of rigid-body dynamics, including frictional/inelastic collisions, for collections up to several hundred elements. We simulated low-speed collisions between km-scale bodies with the same overall parameters as those done by Leinhardt et al (2000).
Collisions between equal-mass objects at low speeds (<103 cm s-1) were simulated for both head-on and off-center collisions with 190, 390, and 762 elements total for power-law mass spectrum objects. Very low-speed head-on collisions produced single objects from the coalescence of the the impactors. For slightly higher speeds, extensive disruption occurred, but re-accretion produced a single object with most of the total mass. For increasingly higher speeds, the re-accreted object has smaller mass, producing finally complete catastrophic disruption with all sub-elements on escape trajectories and only small amounts of mass in re-accreted bodies.Off-center collisions at moderately low speeds produce two re-accreted objects of approximately equal mass, separating at greater than escape speed. At high speed, the complete disruption occurred as with the high-speed head-on collisions.Low to moderate speed head-on collisions resulted in objects of mostly oblate shape, while higher speed collisions produced prolate objects, as did off-center collisions at moderate and high speeds. Collisions carried out with the same dissipative coefficients (coefficient of restitution \epsilonn=0.8, zero friction) as used by Leinhardt et al (2000) result in a somewhat lower value for QD*\approx1.4 than the value of 2 found by them, while collisionswith friction and a lower coefficient of restitution (\epsilonn=0.5, \epsilont=1, \mu=0.5) yield QD*\approx 4.5.
The authors are members of the Center for Origin, Dynamics and Evolution of Planets (CODEP) at UC Santa Cruz. The work in this paper was supported by NASA grant NNGO4G198G of the Planetary Geology and Geophysics program.
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Bulletin of the American Astronomical Society, 37 #3
© 2004. The American Astronomical Soceity.