US missions to the moon brought back a total of around 300 kilograms of moon rocks. Many samples were found to contain traces of water, but NASA believed the water was a contaminant originating on Earth, because lunar dust had clogged the seals of some of the containers and prevented them from being closed properly.
The presence of water on the moon will be important if a moon base is ever to be established, but for many decades the moon was believed by Western scientists to be dry. Three articles by Professor Arlin Crotts, an astrophysicist from Columbia University in New York, has now examined the history of scientific research on the presence of water on the moon and discovered that the Russians had found water in moon rocks in 1976.
The US sent Clementine to the moon in 1994 to use radar to look for water ice by analyzing the reflected radio waves beamed at the surface, and it provided the first Western proof of crystals of water ice under the lunar surface. The Lunar Prospector mission in 1998 also looked for water, this time by comparing the amount of neutrons emitted from the surface with the amount that should be present if there was no water to absorb them. Even more recently, in 2009, the Indian mission Chandrayaan-I found evidence of water on the moon by using infrared photography.