NASA has announced that it found a "significant amount" of water on the moon as a result of the LCROSS impact last month.
Anthony Colaprete, a scientist on the project, estimated there were about 100 litres of water in the crater where the LCROSS spacecraft hit the moon on Oct. 9.
Colaprete presented some of NASA's data from the spacecraft's instruments, including spectrometer readings that strongly suggest the presence of water.
"Indeed, yes, we found water," Colaprete said at a news conference Friday. "There's not just water, but lots of water."
NASA scientists said the lunar crater they hit was actually wetter than some of the driest deserts on Earth.
NASA's discovery is the result of intentionally crashing the Lunar Crater Observation and Sensing Satellite into the moon and analyzing the explosion and crater that resulted.
There were actually two impacts, the first coming when a rocket stage that had carried a lunar probe hit the crater Cabeus, near the moon's south pole, creating a small crater of its own.
The LCROSS satellite observed the impact, as did the Lunar Reconnaissance Orbiter, the Hubble Space Telescope, three other Earth-orbiting satellites, and telescopes in the western U.S. and Hawaii.
Then, the satellite itself hit the moon. The two impacts created a crater between 20 and 30 metres across, and a plume between 10 and 12 kilometres across.
Colaprete said vapour from the explosion was detected as high as 20 kilometres above the moon's surface.
The impact didn't result in an explosion that was immediately visible, but NASA said it received a great deal of information from the experiment.
'Not your father’s moon'
"We are ecstatic," Colaprete said in a NASA statement. "Multiple lines of evidence show water was present in both the high angle vapour plume and the ejecta curtain created by the LCROSS Centaur impact.
"The concentration and distribution of water and other substances requires further analysis, but it is safe to say Cabeus holds water."
Colaprete said he wasn't sure what the other substances might be, because the mission's focus was on finding water, but they could include carbon dioxide, methane, ethanol or methanol.
"All those are possibilities, but we really need to do the work to see what fits best," Colaprete said.
The researchers also saw sodium in the impact. All of these chemicals are seen in other bodies in space, such as comets, which could indicate the source of the moon's water.
The water on the moon could also come from solar wind or the Earth, or it could be that the water's always been there, NASA said.
Colaprete said some of these chemicals were found on moon rocks retrieved by Apollo astronauts, but their presence was explained away as contamination from the Earth. He said the possibility of contamination from the rocket stage or LCROSS itself has been ruled out.
The NASA researchers said water on the moon could be used by a future human settlement there, not just for drinking and bathing, but as a component for rocket fuel, if manned missions are ever launched from the moon.
"The moon still has many secrets," said Greg Delory, a senior fellow at the Space Sciences Laboratory for Integrative Planetary Sciences at the University of California, Berkeley.
Delory, who was not on the LCROSS team, said the mission's data "is painting a really surprising new picture of the moon. This is not your father’s moon. Rather than a dead and unchanging world, it could be a dynamic and interesting one."
The new data from LCROSS appears to agree with a finding from India's Chandrayaan-1 lunar satellite, which in August found a chemical signature for water all over the moon's surface.