They estimated later that up to six billion metric tons of water ice might be buried in these craters under about 18 inches of soil, in more concentrated deposits than originally thought. However, the evidence was indirect, they cautioned, based on reasonable scientific assumptions given the levels of hydrogen detected, from which water ice is inferred. Since then, Prospector data have also been used to develop the first precise gravity map of the entire lunar surface. While the Moon's magnetic field is relatively weak, Prospector has confirmed the presence of local magnetic fields that create the two smallest magnetospheres in the Solar System. Another scientific landmark is the assembly of the first global maps of the Moon's elemental composition.
Neutrons are subatomic particles that are continually ejected from the lunar soil by cosmic rays.
Scientists hoped that by crashing the spacecraft into a shadowed crater they would be able to find direct evidence of water-ice. More information about lunar water .