His comments come as scientists examine data from a lunar probe which was deliberately crashed into the Moon to try to reveal the presence of water. Nasa had hoped the 4,000mph crash of Lunar Prospector into the Moon's south pole would result in a plume of water vapour.
Initial indications are that the cloud failed to materialise.
But Nasa says it could be several days before any reliable information is available. There is hydrogen but no water. Prospector has done all it could and it has been a wonderful success but all the lunar rocks which have been brought back have not shown any signs of water. The discovery of water on the Moon could open the way to future lunar exploration and even the establishment of a lunar base. Results earlier this year from the Lunar Prospector indicated that there may be between 10m and 300m metric tonnes of water locked away in the polar permafrost of the north and south poles of the Moon.