TERRESTRIAL, LUNAR, AND INTERPLANETARY ROCK FRAGMENTATION

Collected data are presented on mass distributions of fragmented rocks. These can be used to interpret extraterrestrial rock samples. Lunar surface material disturbed by Surveyors is broken in a way characteristic of low-energy, mechnical breakage, as expected. Debris around decameter-scale lunar craters with strewn rock fields also exhibits this property, suggesting that many such craters are secondary impacts. Centimeter-scale debris on the lunar maria shows evidence of extensive regrinding, probably due to repeated primary and secondary impacts, but such debris near Tycho appears not to have been so extensively ground; evidently this results from Tycho's young age. Telescopic asteroids have evidently been fragmented by attenuated shock waves in sporadic collisions, while meteorites are apparently the debris from repeated and/or hypervelocity collisions. © 1969.