NASA Outgassing Materials

The GRAIL mission determined the internal structure of the Moon in great detail for nine months during 2012. Armed with this the new information, GRAIL astronomers were able to redefine the sizes of the largest impact basins on the lunar surface. Enceladus: Enceladus has shown geysers of water that were confirmed by the Cassini spacecraft in 2005. Gravimetric data obtained from 2010 to 2011 confirmed the existence of a subsurface ocean. Even though originally it was thought to be localized, most likely in a region of the icy moon's southern hemisphere, evidence collected in 2015 indicates the subsurface ocean is actually global. Furthermore, in additon to water, these geysers from vents located near the south pole of Enceladus contain tiny quantities of salt, nitrogen, carbon dioxide, and volatile hydrocarbons. Tidal flux from Saturn is apparently responsible for the melting of the ocean water, as well as the geysers. GRAIL has also generated new maps showing lunar crustal thickness. These maps have managed to uncover still more large impact basins on the near-side hemisphere of Earth's Moon--revealing that there are fewer such basins on the far-side, which is the side that is always turned away from Earth. This observation begs the question: How could this be if both hemispheres were on the receiving end of the same number of crashing, impacting, crater-excavating projectiles? According to GRAIL data, the answer to this riddle is that most of the volcanic eruptions on Earth's Moon occurred on its near-side hemisphere.