Dr Alan Binder on the crash-landing

Scientists want to crash-land the Lunar Prospector spacecraft into the Moon's south-pole region. They believe this may help them determine how much water is on the Moon.

The Lunar Prospector went into orbit around the Moon in December 1997, using a suite of sophisticated sensors to survey the Moon's surface.

Alan Binder: Looking for final proof

In January 1998, the scientists revealed that it had detected evidence that ice was present at both lunar poles in regions permanently hidden from the Sun.

The indications are that the ice is buried within the first half metre of lunar soil. There may be up to 3 billion tonnes of it at each pole.

Dr Alan Binder, Lunar Prospectors principal investigator, told the BBC: "The mission officially ends at the end of July in the sense that that's the end of the programme and when the money runs out."

High impact

To confirm the presence of ice, the plan is to send the satellite into a high-speed dive that would dislodge as much buried lunar ice as possible upon impact.

The Moon's south polar region

The collision would throw surface material high above the moon's surface. It could then be studied from ground-based telescopes on Earth and the Hubble Space Telescope.

The impact point would be the permanently shaded region inside a large crater near the lunar south pole.

"This is the confirmation we hope for," said Alan Binder. "We're pretty sure there is ice there. The last act of the Lunar Prospector spacecraft will be to provide the final proof."