London, Oct 24 : New images of a prominent crater on the Moon have revealed dull lunar dust instead of shiny pools of ice, which bashes hopes for large lakes of frozen water at the Moon's poles.
According to a report in New Scientist, the crater in question is the 10.5-km wide Shackleton Crater near the Moon's south pole.
A few craters spanning hundreds of metres pockmark Shackleton's inner wall (arrows), while a mound-like feature (marked "m") probably built up from lunar soil that slid down the crater wall.
A decade ago, NASA's Lunar Prospector spacecraft suggested the Moon's poles boast large concentrations of hydrogen near the surface, which could be in the form of frozen water deposited by comets.
This would be vital for future colonies on the Moon, providing drinking water for astronauts and hydrogen fuel for their vehicles.
The Shackleton Crater on the South Pole had been a prominent candidate for a future base station, since it contains a ledge on its rim that would have been an ideal landing spot.
If the crater also holds frozen water, it would be a perfect location.
But that possibility seemed to evaporate when radar signals formerly attributed to water ice were also found to reflect off sunlit areas where ice could not survive.
So, researchers had hoped that the Japanese spacecraft Kaguya, which launched in September 2007, could shed light on the question by peering down on the region from lunar orbit.
The spacecraft contains a highly sensitive camera that can capture images of the Moon's surface even in the near-total darkness of its south pole.
The inside of the crater receives no direct sunlight. But for a short period during summertime in the Moon's southern hemisphere, a small part of its rim catches a few rays.
These are then scattered to the crater floor.
A team led by Junichi Haruyama of the Japan Aerospace Exploration Agency in Kanagawa analyzed images of the crater taken on these brighter days.
The images were snapped by the spacecraft's Terrain Camera, which can resolve objects as small as 10 metres across.
"It's given us access to the poles that we've never seen before," said team member Carle Pieters of Brown University in Providence, Rhode Island.
The images provided a full profile of the crater - including details of tiny craters on its floor and two landslides from the inner wall.
But according to Pieters, the most striking feature was what was missing.
"If there had been nice, clean ice, we'd have seen brighter reflections from its surface. But none were visible," she told New Scientist.
Instead, the images just revealed dull lunar soil.