After seven months of hibernation and dwindling hopes, the European Space Agency (ESA) has announced that its unmanned Philae comet lander has reestablished contact with the Rosetta mothership and mission control. The European Space Operations Centre in Darmstadt received the first signals on Saturday at 22:28 CEST, indicating that the lander has warmed up and charged its batteries sufficiently to return to active duty.

"Philae is doing very well; it has an operating temperature of minus 35º C (minus 31º F) and has 24 Watts available," says German Aerospace Center (DLR) Philae Project Manager Dr. Stephan Ulamec. "The lander is ready for operations."

ESA says that the washing machine-sized lander has so far sent back 300 data packets outlining its present status during 85 seconds of contact with mission control using the unmanned Rosetta orbiter as a relay. Analysis by DLR indicates that Philae had already been active for some time before contact was reestablished and that another 8,000 packets of data are awaiting download when Rosetta and the lander move back into a favorable position for another transmission.

The Philae lander was the first manmade object to make a soft landing on a comet. On November 12, 2014, it made contact with the surface of Comet 67P/Churyumov-Gerasimenko, but due to a malfunction in its landing systems it was unable to anchor itself. As a result, it rebounded four times before finally coming to rest at an unconfirmed location that has been called Abydos.

Unfortunately, the spacecraft landed on its side next to a cliff wall, where not enough sunlight could reach its solar panels and provide power. After 54 hours, the batteries went dead and Philae went into hibernation 15 November 15, 2014 at 01:15 CET. After a failed attempt to reestablish contact in March, Rosetta has been keeping a watching brief in hopes of the landing waking up. Now that that has happened, the pioneering mission can continue to expand our knowledge of comets. Good news!

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