Time running out for Philae
Time is running out for ESA's Philae comet lander as it faces terminal shutdown in about three weeks. According to the German Aerospace Center (DLR), the unmanned spacecraft last heard from on July 9, 2015 will face a "lander hostile" situation by the end of January as Comet 67P/Churyumov-Gerasimenko moves farther away from the Sun. Despite this, mission control is making a last-ditch effort to revive the lander.
Despite repeated efforts, Philae has remained silent for six months as it lies on its side somewhere on the surface of Comet 67P. However, engineers believe that the lander may still be operational despite the loss of two of its radio transmitters and receivers, and on January 10 the DLR will make one last try at bringing it back to life.
A command will be sent that will order Philae to start its reaction wheel. This wheel, which was used to stabilize the lander during its descent to the comet surface, will be used to try and spin Philae in the extremely low gravity. The hope is that it will shake free the dust that has been accumulating on its solar panels since the comet became active and perhaps angle the craft so it collects more sunlight. However, the DLR stresses that the craft may be too far gone and may not respond at all.
Whether mission control succeeds or fails, the DLR says that Philae is rapidly approaching the end of its working life. Comet 67P is heading back to the outer Solar System and will soon be 300 million km (186 million mi) from the Sun. As it draws farther away, Philae's solar panels generate less electricity and the lander will soon be unable to power its systems or keep its electronics from freezing. When its temperature drops below minus 51º C (minus 60º F), it will no longer be able to function or be capable of reactivating.
Meanwhile, mission control says that it will continue to monitor communications for the next couple of weeks for any transmissions from Philae.
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, 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 on November 15, 2014 at 01:15 CET. After a failed attempt to reestablish contact in March, the Rosetta orbiter mothership kept watch until contact was briefly reestablished on June 14, 2015. A possible signal was detected on December 21-22, 2015, but this was dismissed after analysis.