COMPACTION BY IMPACT Or UNCONSOLIDATED LUNAR FINES

New Hugoniot and release adiabat data for 1.8 g/cm3 lunar fines (sample, 70051) in the N 2 to 70 kbar range demonstrate that upon shock compression intrinsic crystal density (. 3.1 g/cm3) is achieved under shock stress of 15 to 20 kbar. Release adiabat determinatioc;s indicate that measurable irreversible compaction occurs upon achieving shock pressures above . k kbar. For shocks in the r y 7 to 15 kbar range, the inferred post-shock specific volumes observed decrease nearly linearly with increasing peak shock pressures. Upon shocking to ,x,15 kbar the post-shock density is approximately that of the intrinsic minerals. if the present data for 70051 are taken to be representative of the response to impact of unconsolidated regolith material on the moon, it is inferred that the formation of appreciable quantities of soil breccia can be associated with the impact of meteoroids or ejects at speeds as low as