Principal science results from Surveyor 5

The area of Mare Tranquillitatis in which Surveyor 5 landed appears to be similar to sites in Oceanus Procellarum. The gross elemental composition of the surface material and its response to a magnet are similar to those of a basalt. The debris layer appears to consist of aggregates of the order of 1 cm in diameter consisting of fine grains and set in a matrix of less-coherent fine grains (most of them 2 to 60 μ in diameter) mixed with some rocky fragments 1 mm and larger. The static bearing strength is less than 104 dynes/cm2 for the upper few millimeters and averages approximately 3 × 105 dynes/cm2 for the upper few centimeters. The evidence suggests that chemical differentiation has occurred in the moon, probably owing to internal heat sources; this is consistent with the hypothesis that the maria are basaltic volcanic flows.