Strength of the lunar dust.

Lunar surface material must have at least enough strength to permit maintenance, against lunar gravity, of the crater wall slopes and heights observed in the Ranger 7 photographs. Slopes and heights in craters which appear to be overlain with granular material permit setting lower bounds to its strength. The lower bound for the mass bearing capacity is 10 g/cm2 on a strip of 0.1-meter width, and 100 g/cm2 on a strip of 1-meter width.