That's why scientists are so interested in water at poles, and the fact Moon dust works well with microwaves and could theoretically be used to make a paved surface if you created roads.

BBC: 3D printers could use Moon rocks, say scientists

Lasers beamed from landing craft could, he says, power rovers in sunless areas of the moon or Mars, such as craters where water might be found.

ECONOMIST: Monitor

"It's quite likely that this moon will now join the ranks of Mars and Jupiter's moon Europa where you might have liquid water - and the biologists could start getting interested in this being a place were life might possibly arise, " enthused Dr Torrence Johnson, a Cassini scientist from Nasa's Jet Propulsion Laboratory in California.

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And water would be all the more exciting on Ganymede because it is the largest moon in the solar system (larger even than the planets Mercury and Pluto) and, like earth, it has a permanent magnetic field that protects part of its surface from bombardment by certain sorts of life-destroying radiation.

ECONOMIST: Blue moon