Radio Science

Lunar Surface Mechanical Properties: Surveyor Results


  • E. M. Christensen


Lunar surface mechanical properties have been interpreted from the interactions of five Surveyor spacecraft with the lunar surface (exclusive of the surface sampler). The lunar soil at the one highland and the four lunar mare landing sites is remarkably similar, even though these sites are widely separated. The soil is predominantly fine-grained and granular; it is estimated to have a cohesion value between 0.05 and 0.17 N/cm2. The static bearing strength of the soil increases with depth. It is estimated that, at the surface, the strength is less than 0.1 N/cm2; at a depth of 4 cm, for a 25-cm-diameter plate, the strength is somewhat greater than the originally estimated 4 to 6 N/cm2. The soil, at least in the upper few centimeters, is compressible.