 The Apollo 17 Lunar Surface Gravimeter on the Moon with ALSEP central station in background. | |
| Acronym | LSG |
|---|---|
| Uses | Gravitational wave detection, Seismology |
| Notable experiments | Apollo 17 |
| Inventor | Lucien LaCoste and Arnold Romberg |
| Manufacturer | Bendix Corporation, LaCoste Romberg, Arthur D. Little |
The Lunar Surface Gravimeter (LSG) was a lunar science experiment that was deployed on the surface of the Moon by the astronauts of Apollo 17 on December 12, 1972. The LSG was conceived by its principal investigator Joseph Weber. Weber proposed a number of experimental methods for the detection of gravitational waves, and would go on to be described as the "founding father" of gravitational wave detection. The experiment aimed to measure changes in the local gravitational strength on the Moon's surface through the use of a gravimeter. These measurements were intended to provide insight into the internal structures of the Moon as it tidally deformed due interaction with the gravitational fields of the Earth and Sun. In addition the experiment hoped to contribute experimental evidence of the existence of gravitational waves.
The instrument as a whole was built by Bendix Corporation, who were also responsible for providing operational support for all packages of the Apollo Lunar Surface Experiments Package (ALSEP) flying as part of the Apollo Program. The instrument's primary sensor was built by LaCoste Romberg, a notable producer of gravimeters. The sensor was based on a modified LaCoste and Romberg D-meter and consisted of an adjustable mass on a sprung lever attached to the instrument's measurement electronics. It was capable of measuring gravity to 1 part in 105.
The gravimeter unit that was deployed on Apollo 17 was not properly calibrated and could not be properly zeroed as the instruments balance weights were too light for use in the Moon's gravity. Whilst the experiment continued to be used as a one-axis seismometer, the data received back was noisy and required more modern analysis techniques before the experiments data was proven valuable. The instrument continued to operate until September 30, 1977 when operations support for ALSEP was terminated due to budgetary constraints. Later understanding of gravitational waves showed that even if the experiment had worked as intended, it would not have been sensitive enough to detect them. Two conceptually similar experiments, the Lunar Gravitational-wave Antenna and Lunar Seismic and Gravitational Antenna, were proposed in 2020 as the Artemis program looks to return to human exploration of the moon.