NASA will tomorrow launch a spectacular mission to bomb the Moon. Their LCROSS mission will blast off from Cape Canaveral, Florida, carrying a missile that will blast a hole in the lunar surface at twice the speed of a bullet.

The missile, a Centaur rocket, will be steered by a shepherding spacecraft that will guide it towards its target - a crater close to the Moon's south pole.

Scientists expect the blast to be so powerful that a huge plume of debris will be ejected.

The attack on the Moon is not a declaration of war or act of wanton vandalism. Space scientists want to see if any water ice or vapour is revealed in the cloud of debris.

Though the Moon mostly a dry airless desert, they believe ice could be trapped in crater shadows near the south pole which never receive any sunlight. If so it could provide vital supplies for a manned moonbase.

Last year, British scientists identified regions where water might be found on the Moon and estimated that there could be enough to fill one of Europe's largest reservoirs.

The spacecraft will not head straight for the Moon. First it will orbit the Earth a number of times while its precise target is identified. Finally, it will send the missile into the Moon at twice the speed of a bullet on October 8.

The shepherding spacecraft will follow close behind, taking pictures and analysing the ejected debris as it looks for evidence of water. It has just four minutes to do this before it crashes into the Moon itself, producing a spectacular explosion that should be visible in amateur astronomers' telescopes.

It is a busy time for Moon crashes. Last week Japan's Kaguya probe collided with the Moon at the end of its own mission.
http://www.scientificamerican.com/article.cfm?id=nasas-mission-to-bomb-the-moon-2009-06