Wednesday, October 13, 1999 Published at 17:16 GMT 18:16 UK
No ice detected after lunar smash
Lunar Prospector: A dramatic ending
The controlled crash of Nasa's Lunar Prospector spacecraft on the Moon did not throw up any signs of water.
Scientists reached this conclusion after digging through extensive data from Earth- and space-based observatories.
The daring experiment, which destroyed the spacecraft, took place when the probe had reached the end of its useful life.
Scientists suspect that ancient cometary impacts on the Moon delivered ice that is now hidden in permanently shadowed regions at the Moon's poles. Large amounts of hydrogen measured indirectly from lunar orbit by Lunar Prospector during its mapping mission support this idea.
Research group leaders from the University of Texas at Austin announced their results on Wednesday at an astronomers' meeting in Padua, Italy.
"There are several possible explanations why we did not detect any water signature, and none of them can really be discounted at this time," said Dr Ed Barker, assistant director of the university's McDonald Observatory.
These explanations include:
The failure to find water is disappointing, but the chances of detection had been assessed to be less than 10%. It does not rule out that water is present.
The $63 million Lunar Prospector was launched in January 1998. In March 1998, mission scientists announced the first suggestions of the presence of water ice. They later estimated that up to six billion metric tonnes of water ice may be buried in these craters, under about 18 inches of soil.
Main image by Boris Rabin, Nasa Ames