When it comes to comets, J marks the spot. The European Space Agency has announced the landing site for its Rosetta mission to comet 67P/Churyumov-Gerasimenko, following a meeting this weekend to whittle down a shortlist of five possibilities.
The J landing spot, on the 鈥渉ead鈥� of the comet, was chosen for having the smoothest surface, but that doesn鈥檛 mean Rosetta鈥檚 lander probe, Philae, will touch down without incident. 鈥淭here are flat areas but there is also rough terrain, there are some cliffs and some boulders,鈥� says Stephan Ulamec, who is in charge of Philae. 鈥淚t is not an easy task.鈥�
ESA will hold a public competition to come up with a better name for the landing site.
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Philae will be released in mid-November 鈥� the exact date will be confirmed later this month 鈥� and take seven hours to reach the comet鈥檚 surface. Rosetta will have to constantly manoeuvre as it orbits 67P to keep in touch with Philae and let ESA monitor the landing process.
Easier landing
If ESA discovers that J is unsuitable between now and November, they have selected a backup site, C. Landing on this spot would give Philae a view of the comet鈥檚 鈥渘eck鈥�, which is of high scientific interest, but J won out as the easier place to touch down. Switching to the backup could delay landing by four weeks, as ESA will have to redo its plans for the descent and scientific analysis. 鈥淲e might be able to skip certain steps, but there is a potential delay,鈥� says Rosetta mission manager Fred Jansen.
When Philae lands, its first task will be snapping a 360-degree panorama of the surface, along with measurements of the gas pressure and dust distribution at the landing site. Later, it will drill beneath the surface and analyse pristine comet material. It is hoped that Philae will also see jets of gas and dust emerging from nearby pits as the comet heats up as it travels towards the sun.
The comet鈥檚 duck-like shape makes the job of landing far more complex, says Jansen. Before arriving at 67P, ESA had expected a roughly spherical comet and predicted a 70 to 75 per cent chance of a successful landing. Now it hasn鈥檛 dared to calculate the odds, as the show must go on regardless. 鈥淟ander delivery has to happen for the mission to continue,鈥� says Jansen.
