Catastrophic rupture of lunar rocks: A Monte Carlo simulation

A computer model based on Monte Carlo techniques was developed to simulate the destruction of lunar rocks by catastrophic rupture due to meteoroid impact. Energies necessary to accomplish catastrophic rupture were derived from laboratory experiments. A crater-production rate derived from lunar rocks was utilized to calculate absolute time scales.Calculated median survival times for crystalline lunar rocks are 1.9, 4.6, 10.3, and 22 m.y. for rock masses of 10, 10², 10³, and 10⁴ g respectively. Corresponding times of 6, 14.5, 32, and 68 × 10⁶ yr are required, before the probability of destruction reaches 0.99. These results are consistent with absolute exposure ages measured on returned rocks.Some results also substantiate previous conclusions reached by others: the catastrophic rupture process is significantly more effective in obliterating lunar rocks compared to mass wasting by single particle abrasion. The view is also corroborated that most rocks presently on the lunar surface are either exhumed from the regolith or fragments of much larger boulders, rather than primary ejecta excavated from pristine bedrock.Permanent address: Max-Planck-Institut für Kernphysik, 6900 Heidelberg, F.R.G.