First image of the lunar plume released

London, Oct 18 : A week after NASA had hit the moon as part of its LCROSS mission, the first image of the lunar material that erupted as a result has been released.

The image was taken by a spacecraft trailing behind the impactor, whose bird's-eye view allowed it to look at the material, which had not yet been captured by the best telescopes on Earth and in Earth-orbit.

Researchers are still studying the faint plume of material to try to identify its composition and search for signs of water.

On 9 October, the LCROSS mission used a 'shepherding' spacecraft to send the two-tonne upper stage of its launch rocket into a permanently shadowed crater at the moon's south pole.

The shepherding spacecraft observed the impact before crashing into the moon itself 4 minutes later.

Scientists had hoped that dust and vapour ejected by the impact would climb high enough to catch sunlight, allowing telescopes to hunt for traces of lunar water in the Ejecta.

But no obvious plume of ejected material was seen by any observers on the ground or even by the Hubble Space Telescope.

Now, scientists have reported that a faint plume of ejecta was pictured via the shepherding spacecraft.

'I think we are the only ones that have images,' New Scientist quoted LCROSS principal investigator Anthony Colaprete as saying.

Ejecta would have had to rise at least 2 km above the surface to be seen from Earth, so the lack of a clear detection from ground-based telescopes suggests most of the ejecta stayed below that altitude.

On the other hand, the LCROSS shepherding spacecraft was flying right behind the rocket stage, thus it was able to peer down into the crater from overhead and see ejecta that did not get lofted very high.

'The ejecta had to only come out and get into the sunlight a little more than a kilometre [high] for us to see it. It only had to rise half as high,' said Colaprete.

The researchers are analysing the images to try to determine the plume's extent, which will allow them to estimate the total mass that was kicked up in the impact.

And they are scrutinising spectral observations of the impact 'flash' - created on the surface at the time of impact, the crater's heat-and the ejected material to try to measure the composition of the material at the impact site.

'Our spectrometers worked very well and we got data from beginning to end. It's a matter of analysing it now - you have to be careful because you're looking for small [spectral] signatures,' said Colaprete.

Talking of any evidence of water on the moon, he said: 'Stay tuned.'

The researchers are aiming to have an analysis of the data done by mid-November.

--ANI