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Europe prepares to INVADE comet: Rosetta landing site chosen

No word yet on whether backup site is labelled 'K'

The European Space Agency has selected a site for the Rosetta space probe's lander, which is attempting to touch down on comet 67P/Churyumov-Gerasimenko.

The region – labelled Site J – lies at the top of the rock, which is unevenly shaped and measures about 4km across at its widest point.

The Rosetta craft is now within 30km of the comet and has beamed back data which has allowed scientists to select the safest possible target, as well as a back up in case conditions change.

Once it draws close enough, Rosetta will launch a spider-shaped lander called Philae, which will make a seven hour descent before slowing to "walking speed" and anchoring itself in place with harpoons and ice screws.

"As we have seen from recent close-up images, the comet is a beautiful but dramatic world - it is scientifically exciting, but its shape makes it operationally challenging," says Stephan Ulamec, Philae Lander Manager at the DLR German Aerospace Centre.

The landing would still be difficult, he continued, because there is no ideal spot on the comet. Landing a craft on a roughly spherical object with a wildly uneven surface and just a tiny gravitational pull is known to be very difficult. Some estimates have put the chance of success as roughly 75 per cent, leaving a wide margin of error.

"None of the candidate landing sites met all of the operational criteria at the 100% level, but Site J is clearly the best solution," he admitted.

One of the most important aspects of the landing zone is that it has good lighting conditions, allowing for periods of light as well as darkness, which is crucial in helping Philae cool down its machinery.

"It's relatively flat, but there are still some cliffs in this terrain; there are still boulders. So, it's not easy to land on 'J'," said Philae project manager Stephan Ulamec of the German Space Agency.

"We're getting very close now, and it is fascinating but I have to say also quite frightening to some degree - that 20 years of work boils down now to just a few hours. Are we going to be successful, or will we be unlucky, hitting a boulder that just happens to be under the lander?"

If all goes according to plan, Rosetta will be the first mission to successfully land on a comet. It is designed to test the chemicals within the comet and perhaps shed some light on how water – and perhaps even life – ended up here on earth.

"We will make the first ever in situ analysis of a comet at this site, giving us an unparalleled insight into the composition, structure and evolution of a comet," said Jean-Pierre Bibring, a lead lander scientist and principal investigator of the CIVA instrument at the IAS in Orsay, France.

"Site J in particular offers us the chance to analyse pristine material, characterise the properties of the nucleus, and study the processes that drive its activity." ®

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