_http://www.timesonline.co.uk/tol/news/science/space/article6916297.ece
Substantial water reserves appear to be present beneath the lunar surface, Nasa announced today.
Crashing in two separate parts into the Cabeus crater at the Moon’s South pole, the Lunar Crater Observation and Sensing Satellite (LCROSS) probe was the most sophisticated attempt yet to detect water on the moon.
The $79 million (£47 million) mission ended on October 9 with a 5,600mph (9,012km/h) crash onto the lunar surface carving a new crater within Cabeus, measuring around 60ft (18m) wide and 13ft (4m) deep.
The leading rocket was designed to kick up dust from the lunar crater. Trailing four minutes behind, the second LCROSS component made spectroscopic measurements of the composition of the lunar dust, with the aim of picking up the chemical signature of water.
Nasa had predicted that the impact would be powerful enough to send a 6km high plume of dust up from the Moon’s surface that would be visible from Earth through a telescope.
No plume was visible from live images beamed back to Earth and during the first few hours there was widespread confusion over whether the mission had been a total failure. Nasa subsequently announced that, although the plume wasn’t as high as expected, enough dust had been kicked up and data had been obtained.
The smaller plume was in part due to a last-minute change of target for the impact. Originally, the crash was due to occur at the Cabeaus A crater, which is significantly shallower than Cabeaus, so the plume would have been more easily visible.
The permanently shadowed area of the south pole, where temperatures can reach -170C (-274F), was selected as the most likely site for assessible water reserves. This region has not been in direct sunlight for at least two billion years.
The Bush Administration pledged a return to the Nasa glory years by sending astronauts to the Moon by 2020 with the long-term goal of setting up a permanent lunar base. However, preparations for a manned Moon would require an increase in Nasa’s annual spending of around $3 billion and most early proposals counted on ice being found near the lunar poles, which could be used for drinking, for irrigation and for rocket fuel.
LCROSS was launched as a “low-cost, fast-track” mission to do some groundwork.
In September, spectroscopic measurements of the lunar surface by the Indian satellite Chandrayaan-1 and Nasa’s Cassini and Deep Impact spacecraft detected evidence of bound oxygen and hydrogen in the Moon’s surface dust, which implied that water is present. However, the surface molecules are bound up in minerals at the surface, which would still appear exceptionally dry by terrestrial standards. Scientists estimate that it would take about 730 square metres of dirt to produce a single glass of water.
The LCROSS mission was not the first attempt to gather evidence of water from the lunar craters. In 1999, Nasa slammed the $63 million Lunar Prospector probe into a crater at the Moon’s south pole after it completed its 19-month mission, but the impact failed to kick up enough dust and debris to determine the presence of water.
