Soil mechanics surface sampler


  • R. F. Scott,

  • F. I. Roberson


A lunar surface sampler essentially identical to that operated from Surveyor 3 was mounted on Surveyor 7 and performed flawlessly on the moon throughout a range of operating temperatures from +180°F to −167°F. The motor current was sampled during lunar bearing and trenching tests, and these data, together with preflight calibrations enabled us to calculate the forces involved in these tests. After minimal lunar surface testing, the surface sampler was employed to release the sensor head of the α-scattering instrument, which had jammed in its background position. Subsequently, the sensor head was relocated to analyze a rock and, still later, to analyze some subsurface lunar material. The mechanical tests of the surface in the vicinity of Tycho indicated that the surface behaved in a manner that was quantitatively similar to the behavior of the material close to Surveyor 3, but the surface near Tycho appeared qualitatively to be more deformable and less brittle. A rock was weighed and found to have a density between 2.4 and 3.1 g/cm3 (earth basis). Another rock was broken by a moderately hard blow from the sampler. The soil varied in depth from 1 to at least several inches over underlying rock fragments near Surveyor 7. Little adhesion of lunar soil to the mirror surface of the α-scattering experiment sensor head was observed over a 24-hour period.