- Copyright © 2003 Society of Exploration Geophysicists
The only gravity measurements made on the surface of a heavenly body were on the moon during the Apollo 17 mission in 1973. An obvious objective was to meet the challenge of making gravity measurements on an extra terrestrial body. More specific objectives were to make an Earth-moon gravity tie, and to investigate the buried structure of the Taurus-Littrow valley, the Apollo 17 landing site. This valley lies between the North Massif and the South Massif and the nature of the valley fill was to be determined.
NASA experiments are carried out by teams. I was principal investigator of what came to be known as the Traverse Gravimeter Experiment (or TGE). The other members of the scientific team were George Thomson and Brian Dent of Stanford University, Hans-Gert Kahle, now at ETH, Zurich, and Sheldon Buck of MIT's Draper Laboratory. The measurements on the Moon were made by two Apollo 17 astronauts, Gene Cernan and Jack Schmitt. The third astronaut, Lee Evans, stayed in orbit around the Moon during the mission. The role played by the astronauts was not only obviously vital to the experiment, but the diligence and enthusiasm with which they performed the measurements were absolutely exemplary.
This paper is based largely on the report by Talwani et al. (1973) which was a part of the NASA preliminary Apollo 17 report 13-1—13-13, 1973. The following abbreviations are used in this paper: ALSEP = Apollo lunar surface experiments package; EVA = extra vehicular activity; LM = lunar module; LRV = lunar rover; SEP = surface electrical properties package; TGE = Traverse Gravity Experiment; VSA = Vibrating String Experiment
The Bosch-Arma VSA used for TGE is a double-stringed instrument (Figure 1); the difference frequency between the two strings Δfn is given by the following expression when the sensor …