We鈥檙e there, now where do we put the spacecraft? The European Space Agency鈥檚 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.
鈥淚t鈥檚 a good compromise,鈥� says Philae manager Stephan Ulamec.
The team has chosen three spots, labelled B, I and J, on the comet鈥檚 鈥渉ead鈥�, and two on the 鈥渂ody鈥�, 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.
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Each site covers 1 square kilometre, as navigational uncertainties mean it isn鈥檛 possible to target a more precise area. Site A, in the valley between the comet鈥檚 head and body, would be interesting scientifically but might prove too challenging due to the complex gravitational pull from both sections. 鈥淭here is no one single nice big flat area,鈥� says Wright.
鈥淚t鈥檚 a bit frightening because the terrains are all difficult,鈥� says Ulamec. The team will now scrutinise the sites using Rosetta鈥檚 cameras, and make a final decision in September. No spacecraft has ever landed on a comet, so there is much to look forward to.
鈥淭he high-resolution images are just incredible,鈥� says team member Ian Wright of the Open University in Milton Keynes, UK. 鈥淎s a human being I can say, wow, that would be an amazing place to have a look at.鈥�
This article will appear in print under the headline 鈥淗ow to park on a comet鈥�
