The European Space Agency orbiter SMART-1 is expected to crash on the surface of the moon Sunday— on purpose.

The 285-kilogram spacecraft, which was launched in September 2003 and has been orbiting the moon since November 2004, will end its mission by crashing into the moon.

The dust and rock from the impact could rise up to 20 kilometres from the lunar surface and may be visible to amateur astronomers using home telescopes.

SMART-1 is expected to hit the moon in a volcanic "lake" called Lacus Excellentiae in the southern hemisphere. The rocks and dust released in the impact are expected to give astronomers a better idea of the moon's composition and origin.

The craft was launched, along with two other satellites, from French Guiana on Sept. 27, 2003. Its mission is to test new technology, includingnew solar powered ion thrusters and miniaturized infrared and X-ray cameras.

The ion engine converts solar power into electricity to convert atoms of xenon gas into plasma, which is shot out of the engine at high speed.

Ion propulsion is less powerful than conventional chemical rockets but it can run for longer using the same mass of propellant.

During its orbit of the moon, the satellite took up to 1,000 images per week of the lunar surface. It took images of the same lunar features at different angles to create a three-dimensional map of the surface.

It also used its X-ray camera to determine the chemical composition of the moon. In June 2005, the ESA announced that SMART-1 had found calcium on the moon, the first time the element had been found there.

SMART-1 is small (about the size of a dishwasher, but with 14-metre solar wings), light and cheap as satellites go. The total cost was 110 million euros or about $156 million, about a fifth of most major science missions.

The satellite is the first mission in the ESA's Small Missions for Advanced Research in Technology program. The missions are designed to test new technologies on small, inexpensive missions before using them on larger projects.

It was built by the Swedish Space Corporation on behalf of the ESA.