Early on Tuesday, the first NASA spacecraft to visit the Moon for 25 years is due to blast off from the Kennedy Space Centre in Florida. Lunar Prospector is cheap, lightweight and tiny, but it should provide a wealth of scientific data and even search for water as it orbits the Moon just 100 kilometres above the surface. This report from Martin Redfern of BBC Science.
Lunar Prospector is one of the first of NASA's so-called Discovery missions, scientific space probes characterised by the slogan 'cheaper, better, faster'. It weighs a mere 300 kilograms, was built and tested in 18 months and cost just $63 million.
That's all in stark contrast to the Apollo Moon missions of the sixties and seventies. They landed a total of twelve astronauts on the Moon, who returned with more than a ton of rock samples and millions of photos. But they still left most of the Moon unexplored.
Lunar Prospector won't land on the Moon at all, but its sophisticated instruments will be able to analyse the rocks from orbit and sniff out faint traces of escaping gas. They will also map the magnetic and gravitational fields of the Moon, revealing details of its internal structure.
Prospector's orbit takes it over the lunar poles. All the Apollo landings were near the equator. But radar data from a US military probe that passed the Moon in 1996 suggested that there could be billions of tons of water frozen within the lunar soil in a shady crater at the South Pole.
If Lunar Prospector proves that there really is water, it might one day help scientists establish a Moon base there.