Testing Gravimeters for Lunar Surface Measurements

After a study of contingent methods of measuring the local acceleration of gravity on the lunar surface, it was decided that state-of-the-art devices for absolute measurements of gravity on early manned missions to the moon were significantly lacking. Alternative methods of obtaining wide dynaniic-range, Earth-reference measurements were investigated. Initially, the most promising device appeared to be the single vibrating-string meter, which could be employed for traverse studies in lunar exploration. Two such meters were compared in a series of qualitative tests. The vibrating-string gravity meter constructed by Esso Production Research Company (EPRC) was found to be the more promising device of this type for extra-terrestrial applications. During the course of this study, the Bell Aerosystems gravimeter gained attention and was tested in the same manner as the other meters. Although results of testing the Bell system show that the range, stability, and operational characteristics are within the requirements of wide-range lunar gravimetry, further environmental testing of a modified unit is necessary. A prototype instrument for the first lunar base station and traverse gravity measurements is presently being constructed.