Rosetta team gets green light for landing on rubber-duck comet

A Rosetta mission "selfie" was taken about 10 miles from the surface of the comet 67P/Churyumov-Gerasimenko on Oct. 7.
A Rosetta mission “selfie” was taken about 10 miles from the surface of the comet 67P/Churyumov-Gerasimenko on Oct. 7.
(European Space Agency)

It’s official! After hovering around comet 67P/Churyumov-Gerasimenko for two months, the European Space Agency’s Rosetta spacecraft has gotten the go-ahead to deliver a special lander to a specific spot on the comet on Nov. 12.

The decision, made Tuesday, is a landmark in the first attempt to perform a soft touchdown on the surface of a comet, which is an ancient remnant of the formative years of the solar system.

Rosetta’s lander, named Philae, is set to descend to a spot called Site J, on the smaller of the two lobes that seem to make up the approximately 2.5-mile-wide comet. (If you think the comet looks like a rubber duck, then Site J is on the duck’s head, rather than its body.)

“Now that we know where we are definitely aiming for, we are an important step closer to carrying out this exciting -- but high-risk -- operation,” Fred Jansen, the ESA’s Rosetta mission manager, said in a statement.


Since Rosetta’s arrival around 67P/Churyumov-Gerasimenko, the spacecraft has been checking out the comet from ever closer vantages, narrowing the distance from about 62 miles on Aug. 6 to about six miles from the comet’s heart. (It’s taken selfies with the comet too.)

In the run-up to Philae’s release, there are to be a number of other checkpoints during which mission officials will decide whether to continue forward. If all goes well, Rosetta will back up from the comet to about 14 miles out before letting Philae go. Then, as Philae descends to the surface of 67P/Churyumov-Gerasimenko over seven hours, it will take snapshot after snapshot of the comet and sample the dust, gas and plasma nearby.

When it lands, Philae will use harpoons and ice screws to fasten itself and make sure it stays put on the low-gravity comet.

How long Philae can use its suite of 10 instruments to study the comet depends largely on how well its solar-powered batteries can recharge -- and that depends on how much dust ends up obscuring the solar panels. But either way, things will start to get uncomfortably warm as the comet hurtles toward the sun, and by March 2015, it will probably be too hot for the lander to continue working.

Rosetta will stick with the comet for much longer, following 67P/Churyumov-Gerasimenko through its closest approach to the sun in August 2015 and then out again, toward the outer solar system.

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