This is something that Lunar Prospector will help to clarify over the coming months.

ECONOMIST: At least lunar gold-diggers will be able to take a shower

As it flew over the poles, Lunar Prospector picked up bursts of slower neutrons, revealing hydrogen there.

ECONOMIST: At least lunar gold-diggers will be able to take a shower

Dr Goldstein, however, realised that Lunar Prospector could be used to test for the presence of water directly albeit only once.

ECONOMIST: Creative destruction

One of the four instruments on Lunar Prospector is a neutron spectrometer.

ECONOMIST: Divining water

The same design of instrument was used on the Lunar Prospector spacecraft that discovered ice in the shadowed regions of the Moon's poles in 1998.

BBC: Ice reservoirs found on Mars

After a month of fly-bys over the south pole, Lunar Prospector should be able to confirm the presence or absence of water once and for all.

ECONOMIST: Divining water

Also, Lunar Prospector will be able to analyse gases that seep out of cracks which open up during moonquakes, if it is lucky enough to fly over one.

ECONOMIST: Divining water

The discovery of ice is sure to overshadow the many other things Lunar Prospector will achieve (such as the first complete map of the moon's gravity, also announced this week).

ECONOMIST: At least lunar gold-diggers will be able to take a shower

Lunar Prospector itself provided more evidence last year when it used an instrument called a neutron spectrometer to look for the tell-tale signs of hydrogen, one of the elements of water.

ECONOMIST: Creative destruction