Comet 67P/Churyumov–Gerasimenko, where the robotic lander Philae has been "sleeping" since NovemberESA

Philae, the washing-machine-sized robot that landed on a comet late last year, awoke this weekend from a months-long hibernation and surprised scientists with a transmission from outer space. A Twitter account affiliated with the project tweeted the good news.

Philae spent 10 years in space before detaching from the Rosetta spacecraft and successfully landing on a comet in November. The lander's mission was to report back to Rosetta—and, by extension, scientists on Earth—about the composition of its new comet home. But Philae's first battery pack ran out about 60 hours after landing, and a rougher than planned bounce-landing made it unclear—until now—whether the robot ended up in a spot that would receive enough sunlight for a second, solar-powered battery pack to recharge Philae back to life.

“Philae is doing very well,” wrote Stephan Ulamec, a Philae project manager, in a blog post for the European Space Agency. More from the ESA blog:

Rosetta’s lander Philae is out of hibernation! ... For 85 seconds Philae “spoke” with its team on ground, via Rosetta, in the first contact since going into hibernation in November.

Now the scientists are waiting for the next contact.  There are still more than 8,000 data packets in Philae’s mass memory which will give the DLR team information on what happened to the lander in the past few days on Comet 67P/Churyumov-Gerasimenko.

Now that Philae is awake, scientists hope to learn more about the shape, density, temperature, and chemical make-up of the comet. They'll also analyze how the comet reacts to cosmic dust and solar wind.

The origins of Philae’s name are perhaps as lofty as its goals. It is an homage, ESA says, to an obelisk found on the island of Philae, in the Nile region of Egypt, that held the final clues for deciphering the hieroglyphs on the Rosetta Stone—the hunk of inscribed rock that unlocked human’s modern understanding of ancient texts and symbols.

“No one knows,” the ESA says, “precisely how long the lander will survive on the comet.”

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