VELOCITY DISTRIBUTION OF FRAGMENTS FORMED IN A SIMULATED COLLISIONAL DISRUPTION

The velocity distribution of fragments resulting from catastrophic disruption was determined experimentally which is of great importance to understand the collisional evolution of planetary bodies. Basalt and alumina spheres 6 cm in diameter were shattered by nylon spheres 7 mm in diameter at velocities of 3 ∼ 4 km/sec. From high-speed photographic records taken from two orthogonal directions, velocity, initial position, and size of a few hundreds of fragments were obtained using an image processor. The three-dimensional fragment velocity determined for some prominent fragments is expressed as the - 1 6 power of fragment mass for fragment sizes larger than a few millimeters. The fraction of energy, momentum, and angular momentum partitioned into the large major fragments, core, and the fast fine ejecta from near the impact site were evaluated. About 1% of the initial kinetic energy was found to be partitioned into the major, large fragments. Cores were minor carriers of energy and momentum, while fine ejecta played a significant role as carriers of the three kinetic quantities. © 1991.