Not so hostile: The Moon may be wetter than we thought.

Credit: NASA/Lick Observatory

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PARIS: The ancient astronomers once deemed the Moon, like Mother Earth, to be awash with water and gave fanciful names to its "seas."

The space age, of course, revealed these oceans, or Mare, to be desolate, bone-dry basalt plains – and ever since, the Moon has been saddled with the reputation as a hostile place forever lacking a key ingredient for life.

But this image may need a makeover, if some of the hopes sketched in a new scientific study turn out to be true.

Icy lunar poles

Published this week in the British journal Nature, the paper puts forward evidence that water has been a part of the Moon since its early existence. And it strengthens speculation that the precious stuff may be found at the lunar poles.

A leading theory is that the Moon was created when a Mars-sized object whacked into the infant Earth, some 4.5 billion years ago, sending molten debris into orbit that coalesced and cooled to form our planet's satellite.

The violence of this collision would have vaporised the proto-Moon's light elements, including those for water, in a flash. But a close examination of glassy, pebble-like beads brought back by the Apollo missions has revealed a surprise.

Previous examination of these rocks – the result of a volcanic outpouring some 3.5 billion years ago – had found no signs of water, a finding consistent with the "waterless Moon" scenario.

"Minute but intriguing concentrations"

Geologists led by Alberto Saal at Brown University, Rhode Island, have taken a new look, this time using a souped-up version of a method called secondary mass ion spectrometry that is 10 times more sensitive than previous versions.

They found minute but intriguing concentrations of water in the pebbles, "up to 46 parts per million [ppm]," said Erik Hauri of the Carnegie Institution for Science in Washington DC. The team say that this water is a trace of far larger concentrations that must have existed in the Moon's interior before the fire fountains swept into action.