If the experiment is successful it will be confirmation that the Moon could harbour millions of tons of water which could be used to make rocket fuel for the manned exploration of the Solar System.
Engineers at the American National Aeronautics and Space Administration (Nasa) are crossing their fingers in the hope that the Lunar Prospector probe will survive its last lunar eclipse this week before it is plunged into a crater at the Moon's south pole. The eclipse, when the Moon's shadow prevents the probe's vital solar panels from boosting its on-board batteries, will last nearly three hours. Nasa say that if the spacecraft's batteries survive the blackout, the final descent to the Moon's surface will begin at the end of the week, with the impact itself scheduled for 11am on Saturday, 31 July.
Heat generated by the impact could vapourise up to 40 kilograms of water which would be released over an area covering several square kilometres, said David Goldstein, a lunar researcher at the University of Texas at Austin. "Water vapour will begin to rise off the surface and out of the crater, which is about 4 km (2.5 miles) deep. The gaseous plume is going to rise up for about 16 minutes and then fall back to the lunar surface," said Dr Goldstein.
Hydrogen detectors on the $63m (pounds 39m) Lunar Prospector first detected signs of lunar water last March. Six months later the probe provided data enabling scientists to estimate that the Moon might contain as much as 6bn tons of water ice.
Critics of the lunar water concept include George Parks, professor of geological and environmental sciences and Von Eshleman, professor of electrical engineering at Stanford University in California, who believe that any water has by now reacted with lunar dust to form a "concrete paste".
If cometary water has undergone chemical reactions with minerals, this week's crash is unlikely to detect it, said Dr Goldstein: "There could be water there in the form of hydrated minerals, and it would be much harder to extract."Reuse content