The Apollo 15 mission included the deployment of a small satellite, known as the Apollo 15 Particles and Fields Subsatellite (PFS-1), into lunar orbit. The main objective of the PFS-1 was to measure the Moon's magnetic field, study the lunar gravity field, observe cosmic rays and particles in the lunar environment, and investigate the interaction of the Moon with the solar wind and the Earth's magnetosphere. Data from the subsatellite helped improve the understanding of the Moon's gravitational field, contributing to more accurate models of the lunar interior and surface features. The subsatellite's measurements of the lunar magnetic field provided insights into the Moon's magnetic properties and its interaction with solar and terrestrial magnetic fields. Observations of charged particles and cosmic rays helped scientists understand the lunar environment and the effects of the Moon on solar wind particles.