Blowing of lunar soil by apollo 12: surveyor 3 evidence.

Analysis of discoloration patterns on the camera of the spacecraft Surveyor 3, after the Apollo 12 lunar module landed nearby, indicates that lunar surface particles were eroded and entrained by lunar modute exhaust during the landing and were ejected almost horizontally at 70 meters per second or faster. These particles struck the Surveyor camere and whitenzed its surface.

Lunar surface: changes in 31 months and micrometeoroid flux.

Comparison of pictures of the lunar surface taken 31 months apart by Surveyor 3 and Apollo 12 show only one change in the areas disturbed by Surveyor: a 2-millimeter particle, in a footpad imprint, that may have fallen in from the rim or been kicked in by an approaching astronaut. Vertical walls 6 centimeters high did not collapse and dark ejecta remained dark. No meteorite craters as large as 1.5 millimeters in diameter were seen on a smooth soil surface 20 centimeters in diameter; this indicates a micrometeoroid flux lower than 4 x 10(-7) micrometeoroids per square meter-second at an energy equivalent to about 3 x 10(-8) gram at 20 kilometers per second. This flux is near the lower limit of previous determinations.

Strength-density relations in particulate silicates of complex shape and their possible lunar significance.

Some terrestrial particulate silicate rocks with complex particle shapes have internal friction angles over 45 degrees and cohesion of about 0.1 newton per square centimeter at bulk densities of 0.6 to 0.8 gram per cubic centimeter. Mechanical and other properties of the lunar surface layer, observed with spacecraft, may be consistent with a low bulk density and complex reentrant shapes for the fine particles.

Lunar surface material: spacecraft measurements of density and strength.

The relation of the density of the lunar surface layer to depth is probably best determined from spacecraft measurements of the bearing capacity as a function of depth. A comparison of these values with laboratory measurements of the bearing capacity of low-cohesion particulate materials as a function of the percentage of solid indicates that the bulk density at the lunar surface is about 1.1 grams per cubic centimeter and that it increases nearly linearly to about 1.6 grams per cubic centimeter at a depth of 5 centimeters.

Surveyor v.

Surveyor V has provided the first direct chemical analysis of the lunar surface. In addition, the amount of ferromagnetic material was measured. More than 18,000 television pictures were taken, and a variety of scientific data were obtained.

Surveyor v: lunar surface mechanical properties.

The mechanical properties of the lunar soil at the Surveyor V landing site seem to be generally consistent with values determined for soils at the landing sites of Surveyor I and III. These three maria sites are hundreds of kilometers apart. However, the static bearing capability may be somewhat lower than that at the previous landing sites (2 x 10(5) to 6 x 10(5) dynes per square centimeter or 3 to 8 pounds per square inch). The results of the erosion experiment, the spacecraft landing effects, and other observations indicate that the soil has significant amounts of fine-grained material and a measurable cohesion.

Lunar surface strength: implications of luna 9 landing.

The ability of the lunar surface to support statically the Luna 9 copsule indicates that the surface can bear at least 5 x 10(3) dyne per square centimeter (10(-1) lb/in.(2)). Analysis of the landing dynamics, using available data, gives a lower bound of about 1 to 2 x 10(5) dyne/cm(2), but this estimate may not be conservative because of uncertainties regarding the shock-absorbing system used and the direction of the velocity vector at impact.