Nasa scientists are assessing preliminary data after crashing two unmanned spacecraft into the Moon in a bid to detect water-ice. The first to collide was a 2,200kg rocket stage, which slammed into Cabeus Crater at the Moon's south pole.
Another spacecraft with science instruments followed it down to analyse debris kicked up by the impact. Scientists expected some 350 metric tonnes of debris to be kicked up to altitudes of 10km (6.2 miles) or more. The $79m (£49m; 53m euro) mission is called LCROSS (the Lunar Crater Observation and Sensing Satellite).
No light flash from an impact was immediately apparent in images broadcast on Nasa TV, and some astronomers observing at ground-based telescopes were puzzled by an anti-climax to their viewing efforts. Dr Robert Massey, from the UK's Royal Astronomical Society (RAS), told the BBC: "Maybe there's rather less material to kick up than they had expected.
"They were encouraging amateur astronomers across the western US to look for this. But you need to have something fairly bright to be detected with amateur telescopes on Earth." But Anthony Colaprete, principal investigator for the mission, cautioned: "We don't anticipate anything about presence or absence of water immediately. It's going to take us some time." There are two main components to the mission: the large Centaur rocket upper stage and its smaller "shepherding spacecraft".
The rocket stage hit the Moon at 1231 BST (0731 EDT), travelling at roughly twice the speed of a bullet. The shepherding spacecraft - designed to look for signs of water in the plume - struck the surface four minutes later. It was using onboard spectrometers to look for signs of water, hydroxyl compounds (OH), salts, clays, hydrated minerals and organic molecules in the plume.
The identification of water-ice in the impact plume would be a major discovery, not least because a supply of water on the Moon would be a vital resource for future human exploration. LCROSS was to have helped pave the way for US astronauts to return to the Moon by 2020. But these plans have been under scrutiny since President Barack Obama ordered a sweeping review of Nasa's manned spaceflight programme.
-New Nation
