Volatiles
The south polar region of the Moon was surveyed by the Lunar Prospector spacecraft and a hydrogen signature was detected. Potential sources for this hydrogen include water deposits from comet or meteorite impacts, the solar wind or out-gassing. This crater is sufficiently large that the temperature within the shaded region is below 100 K (−173 °C). This would allow water ice to remain on or near the crater surface for billions of years without sublimating.
Read more about this topic: Cabeus (crater)