Plenty of space and no meters

We’re there, now where do we put the spacecraft? The European Space Agency’s Rosetta probe has been scanning comet 67P/Churyumov-Gerasimenko for sites where its Philae lander could touch down in November. The shortlist is now down to five.

“It’s a good compromise,” says Philae manager Stephan Ulamec.

The team has chosen three spots, labelled B, I and J, on the comet’s “head”, and two on the “body”, A and C (see picture). The letters come from the original list of 10 sites and do not indicate order of preference. Light levels, visibility from Rosetta and surface conditions all influenced the selection, but no one site is perfect.

Each site covers 1 square kilometre, as navigational uncertainties mean it isn’t possible to target a more precise area. Site A, in the valley between the comet’s head and body, would be interesting scientifically but might prove too challenging due to the complex gravitational pull from both sections. “There is no one single nice big flat area,” says Wright.


“It’s a bit frightening because the terrains are all difficult,” says Ulamec. The team will now scrutinise the sites using Rosetta’s cameras, and make a final decision in September. No spacecraft has ever landed on a comet, so there is much to look forward to.

“The high-resolution images are just incredible,” says team member Ian Wright of the Open University in Milton Keynes, UK. “As a human being I can say, wow, that would be an amazing place to have a look at.”

This article will appear in print under the headline “How to park on a comet”