By the (tiny but shiny) light of the silvery Moon

Poets who wax lyrical about the silvery Moon may be on to something. Scientists who blasted a spent rocket into a lunar crater last year released an unexpected treasure trove of elements - including traces of silver.

But the levels are far too low to make it worth opening a lunar silver mine.

More importantly, large amounts of water were discovered at the bottom of the Cabeus crater. Comprising 5.6 per cent of the surface material, it was present in sufficient quantities to be useful to future manned missions.

Less welcome was the detection of surprisingly high levels of mercury in the soil, posing a potential risk to explorers.

Planetary geologist Dr Peter Schultz, one of the scientists from Brown University in Rhode Island, United States, said: "This place looks like it's a treasure chest of elements, of compounds that have been released all over the Moon, and they've been put in this bucket in the permanent shadows."

He believes elements liberated by meteor impacts right across the Moon may have migrated to the cold poles driven by the energy of sunlight. There they had remained trapped within dark and frigid craters that never see the Sun.

Atoms of silver may have been part of that migration.

Fellow expert Dr Kurt Retherford, from Southwest Research Institute in San Antonio, Texas, said the biggest surprise was finding mercury at about the same abundance as water.

"Its toxicity could present a challenge for human exploration," he said.