The Lunar Prospector mission to map the Moon and search for evidence of water is part of Nasa's new Discovery Programme which is intended to create faster, better and cheaper space missions.

Unusual radar data returned in1994 by Clementine, a military craft, suggested that a large area of ice covering up to 31 square miles existed in a deep, shadowed crater near the Moon's south pole.

If Prospector confirms this to be the case then future Moon colonists will have a supply of fuel, oxygen and drinking water.

The probe will spend at least a year mapping the Moon, recording its surface composition, measuring gravity and magnetic fields, and the release of any gases.

The Moon's south pole

By piecing together data about its internal structure, scientists hope to determine the origin of the Moon. Researchers do not kow if it is a chunk of Earth which was blown off by a comet billions of years ago or if it was formed at the same time as the Earth.

The data will add to that gained from the Apollo programme and will also be used for planning future missions.

The total cost of the project is just under $63m, which includes the spacecraft, the science instruments, integration and test, launch and all mission operations. The spacecraft was built by Lockheed Martin Missiles & Space, in Sunnyvale, California.

The project began as a private initiative to show that small, inexpensive missions could be developed in a short time and still provide high quality science.

Lunar Prospector will orbit the polar regions every two hours at an altitude of 60 miles. This is the closest a spacecraft can get to the Moon while avoiding dangerous gravitational anomalies which could pull the probe off course or send it crashing to the surface.

The launch has been postponed several times but it should begin its mapping mission in early 1998. The entire lunar surface will be scanned more than 20 times during the first year.

Periodic corrections to its position will need to be made but if, as expected, there is fuel available at the end of the year, an extended mission is planned with a lower orbit.

Nasa has now selected two more low cost, highly focused projects for the Discovery programme. Genesis will gather samples of the wind flowing from the Sun and Contour (Comet Nucleus Tour) will fly close to three near-Earth comets.
 

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