Rosetta’s countdown to comet landing has begun

Mission scientists put Rosetta spacecraft through final paces before attempted touchdown

comet 67P/Churyumov-Gerasimenko

IN FOCUS  Philae’s landing site, Agilkia, is just above the clearly visible depression on the smaller of comet 67P/Churyumov-Gerasimenko’s two lobes. Everything is on track for the attempted touchdown on the comet on November 12.


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DARMSTADT, GERMANY — So far, it is go for launch of the Philae lander to the core of comet 67P/Churyumov-Gerasimenko on November 12. If all goes as planned, this historic first cometary touchdown will give scientists a front row seat to see exactly what happens to these icy boulders as they near the sun.

But getting the minifridge-sized Philae lander to the surface of 67P is not a simple task, said Andrea Accomazzo, the European Space Agency’s spacecraft operations manager, in a November 10 press conference. Hitting the selected sweet spot on the comet requires  scientists to program the Rosetta spacecraft, orbiting 67P, to push Philae from its back end at exactly the right time and with just enough (but not too much) oomph. Slight miscalculations or poor positioning could be catastrophic for the lander, sending it careening into a boulder or worse.

Scientists designed Philae and Rosetta to study the chemistry and geology of 67P, providing data that could give scientists clues to how the planets became what they are today and whether comets brought water and other ingredients for life to Earth.

Despite all the variables in the planned precision dance, the scientists appeared calm and confident as they talked through the final paces Rosetta and Philae would be put through before the lander’s launch and touchdown. The commands for the separation and landing sequence have already been uploaded to the spacecraft. Later on November 10 the team plans to switch Philae on and start warming it up for Wednesday’s landing, said Stephan Ulamec, the lander’s project manager at the German Aerospace Center in Cologne.

The real nail-biting begins the evening of November 11 as the team works through a series of go, no-go milestones for launch and landing. The slightest deviation from Rosetta’s flight path or any hiccups from Philae could stall the launch, pushing it back several weeks. The last decision to release Philae will be made at roughly 7 a.m.  Central European Time (1 a.m. Eastern Standard Time) on the morning of November 12. After that time, there’s no going back.

“The release depends fully on the spacecraft, not on the comet,” Accomazzo said. He and his team are likening their tedious task to climbing Mount Everest. “If we don’t reach the top,” Accomazzo said, “it’s because the mountain doesn’t want us.”

A RISKY BUSINESS  ESA’s Philae robot is preparing for an extraordinary landing on an ambitious target: comet 67P/Churyumov-Gerasimenko. Here’s how it will get down to the space rock’s surface.  Credit: Images, graphics and animations courtesy of DLR German Aerospace Center and ESA; Narrated and produced by Ashley Yeager

Ashley Yeager is the associate news editor at Science News. She has worked at The Scientist, the Simons Foundation, Duke University and the W.M. Keck Observatory, and was the web producer for Science News from 2013 to 2015. She has a bachelor’s degree in journalism from the University of Tennessee, Knoxville, and a master’s degree in science writing from MIT.

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