More Looney Lunar Spectacles

smh.com.au

A NASA spacecraft will deliberately crash into the moon in January 2009, a collision so violent it will be visible on Earth through a telescope.

The impact will help scientists search for water that might be lurking in deep, dark craters.

In part, the aim of the mission - announced by NASA on Monday - is to help find landing sites for human exploration, a goal announced by the US President, George Bush, in 2004.

Early lunar missions identified abundances of hydrogen in craters near the south pole that are permanently shielded from sunlight, leading to speculation that the hydrogen was bound with oxygen in the form of water.

If shadowed areas on the moon contain water ice, NASA officials said, they would be prime landing sites for humans. Water can be broken apart to produce hydrogen for rocket fuel and oxygen for fuel and breathing.

The spacecraft - the first to strike the moon since NASA's Lunar Prospector in 1999 - will be part of a previously announced mission in which a larger craft, the Lunar Reconnaissance Orbiter, will fly around the moon to map its surface. Both craft will be launched on the same rocket in October 2008, but the smaller impact craft will circle the Earth and moon for 90 days before slamming into the moon's south pole.

The project is called LCROSS, for Lunar Crater Observation and Sensing Satellite. Its manager, Daniel Andrews, of NASA's Ames Research Centre in California, said the upper stage of the rocket that sends the orbiter to the moon would be used as an impact vehicle.

When the 2000-kilogram used rocket slams into a crater at about 9000kmh, Dr Andrews said, it should send up a 1 million kilogram plume of vapour and debris rising 48 to 64 kilometres above the surface. About 15 minutes later the trailing spacecraft, loaded with equipment to determine chemical composition, will fly through the plume, taking and relaying data before it hits the moon.

"We're going to see the impact," Dr Andrews said, "and then fly through the plume while looking into the crater and also looking sideways 90 degrees out into space to see the plume material against the darkness."

The mission will not be NASA's first attempt to do geological studies by smashing robotic probes into distant bodies. In 1999 scientists decommissioned the orbiting Lunar Prospector probe by crashing it into the moon's south pole, but it disappointed them by producing little or no debris because of its shallow impact angle.

The robotic moon missions are the first steps in NASA's plans to return astronauts to the moon by 2018 as a stepping stone to Mars.

The New York Times