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Philae lander enters deep sleep after sending last transmissions from comet surface

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The Philae lander has gone into hibernation on the surface of a comet roughly 300 million miles from earth. After its bouncy (and unprecedented) landing earlier this week, the lander has run out of power, and signals from the unit have ceased.

But just before the last bits of Philae's power ran out, it sent home a series of transmissions containing key information at the core of the Rosetta mission. "It has been a huge success, the whole team is delighted," said Stephan Ulamec, a German scientist who has managed the landing this week. He added in a press release, "Despite the unplanned series of three touchdowns, all of our instruments could be operated and now it’s time to see what we’ve got."

"It has been a huge success."

The shaky landing — which saw Philae bounce twice before landing far away from its planned landing zone — left the unit at the base of a cliff. That's a problem, because the cliff's shadow blocks the lander's solar panels. Before power ran out, scientists at the European Space Agency, which is leading the highly-publicized mission, were able to rotate the lander to position its largest solar panel in the best possible spot to get some sunlight. Nevertheless, it's estimated that it will get just one-and-a-half hours of sunlight every 12 hours — not even half of what they originally planned for.

Nevertheless, the ESA has proclaimed Philae's primary mission objectives complete. The suite of instruments onboard were able to drill and analyze a soil sample, take temperature readings, and use radio waves to study the internals of the comet, among other studies. Of course, the lander has taken a series of unbelievable up-close photos of the comet's surface as well.

The ESA warns that we shouldn't expect to hear back from Philae any time soon. The agency hopes that it may be able to reestablish communications when the lander gets closer to the Sun. Its orbit will be the very closest during August of next year. In the meantime, the Rosetta orbiter — which is conducting numerous studies on its own — is continuing to look for Philae's final landing spot, and it will seek out transmissions from the lander every day when the two are within line-of-sight.

Correction: The 67P comet, as of publication, is roughly 300 million miles from earth, not 4 billion as originally reported. It did, however, travel a cumulative distance of 4 billion miles to reach its destination.