Luna 24 core spherules - Microparticle impact crater and accreta populations as indicators of the past surface environment

Measurements have been performed on Luna 24 core spherules from three different levels down the core (90, 125, and 196 cm) in order to obtain sets of cumulative size distributions for impact microcraters and accretionary particles. Plots of microcrater densities against accreta densities give some evidence of crater-accreta correlation for these spherules. Estimated mean surface residence times for the spherules range from 1000 to 100,000 years, in agreement with results from other workers. The accreta deposition mechanism which acted on the surface of the spherules is constant with depth in the core, suggesting (but not establishing) that it is constant with time