Model Studies of Effects on Lunar Soil of Chemical Explosions

A total of 51 model tests of cratering and soil loosening were conducted using small charges of pentaerythritol tetranitrate detonated at different depths of burial and different gravitational accelerations in a lunar soil simulant to model conditions on the surface of the Moon. Model crater dimensions extrapolated to lunar conditions fall well within the range of sizes of craters expected to be useful in lunar construction. Apparent crater volumes reached their maximum at an optimum depth of burial of eight charge diameters. Modeling to check for adverse model scaling effects was conducted, and results indicated an absence of scaling effects for buried charges. Development of craters from half‐buried charges seems to be influenced by a nonfriction component of strength, which emphasizes the importance when modeling of satisfying laws of similarity, especially with regard to stresses. Cone‐penetration resistance was measured and established that all charges produced substantial loosening of the soil. Measurements of excavatability of the soil showed the same general picture; the results can be extrapolated as a first estimate of excavation effort required on the lunar surface.