This experiment is identical to one deployed on the lunar surface as part of the Apollo 14 ALSEP (Apollo Lunar Surface Experiment Package). It was designed to measure the numbers, velocities, and the directions of electrons and protons near the surface of the Moon as well as the ways these measurements change in time. Such data are valuable in the study of solar wind, the magnetosphere of the Earth and low-energy solar cosmic rays. Analysis of the Apollo 14 data revealed important information about all of these phenomena.
This unit was a qualification model stored at the manufacturer's facility until NASA declared it surplus and transferred it to the Smithsonian in 1982.
Transferred from the NASA - Johnson Space Center