Ice on the Moon
Data from the neutron spectrometer on Lunar Prospector. If hydrogen is present in the lunar soil, its dominant effect would be to decrease the intensity of fast- and medium-energy neutrons. There are two consistent dips in the number of medium-energy neutrons detected, one at either pole, indicating that there are hydrogen deposits in these regions. The scientists working with Lunar Prospector data believe that the hydrogen is most likely to be in the form of water-ice, deposited by numerous meteorites or comets.