MODEL STUDIES OF EFFECTS ON LUNAR SOIL OF CHEMICAL EXPLOSIONS

A total of 51 model tests of cratering and soil loosening were conduct ed using small charges of pentaerythritol tetranitrate detonated at di fferent 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 wit hin the range of sizes of craters expected to be useful in lunar const ruction. Apparent crater volumes reached their maximum at an optimum d epth of burial of eight charge diameters. Modeling to check for advers e model scaling effects was conducted, and results indicated an absenc e of scaling effects for buried charges. Development of craters from h alf-buried charges seems to be influenced by a nonfriction component o f strength, which emphasizes the importance when modeling of satisfyin g laws of similarity, especially with regard to stresses. Cone-penetra tion 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 extrapola ted as a first estimate of excavation effort required on the lunar sur face.