Comet lander loses power but completes "primary" job
- November 17, 2014
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A probe sent to land on a comet for the first time has lost power but managed to complete its “primary science mission,” mission scientists reported Saturday.
They added that the lander might reawaken when there is more light for its solar panels, possibly around when the comet approaches the Sun. The closest approach is next August.
As the scientists with the European Space Agency mission tell it, the Philae lander was on the comet for 57 hours before losing power as a result of its solar panels not getting enough light.
Indeed, scientists had never considered it a sure thing to begin with that such light would be available.
Accordingly, only a possible “extended science mission,” not the “primary” mission, was made contingent on that light and its resulting power. The “primary” mission depended on a separate battery.
As it turned out, mission scientists said, the lack of light seems to be a result of the lander's unexpectedly bouncing twice off Comet 67P/Churyumov-Gerasimenko after an initial touchdown. The bounces left the probe in an unintended spot, in the shadow of a cliff, and are believed to be the result of one or two malfunctions, including the failure of harpoons meant to tie the lander down to its targeted landing site.
Philae remained in contact and able to deliver data and pictures until 1:36 a.m. Central European Time Saturday, mission scientists said. A small adjustment in its position failed to prevent the subsequent power loss, but scientists believe the adjustment may boost the chances of a later reawakening.
The agency had sent a spacecraft called Rosetta to orbit the comet. Rosetta in turn delivered Philae there. Rosetta itself continues to study the comet, mission scientists said.
Agency officials and scientists put a positive face on the overall situation. Fred Jansen, ESA's Rosetta mission manager, predicted “many more months of exciting Rosetta science and possibly a return of Philae from hibernation at some point,” noting that it has been a “rollercoaster week.”
“It has been a huge success, the whole team is delighted,” added Stephan Ulamec, lander manager at the DLR German Aerospace Agency, who monitored Philae's progress from ESA's Space Operations Centre in Darmstadt, Germany, this week.
Despite snafus, all the scientific instruments worked “and now it's time to see what we've got” from the data returned so far, he added.
The lander's exact location on the comet remains only roughly known. The search for that continues, with high-resolution images from Rosetta spacecraft, which is orbiting the comet, under close scrutiny. Meanwhile, the lander has returned unprecedented images of its surroundings.
While descent images show that the surface of the comet is covered by dust and debris ranging up to a meter (yard) in size, panoramic images showed layered walls of harder-looking material. The science teams are now studying their data to see if they have sampled any of this material with Philae's drill.
Data collected by the orbiter is intended to allow scientists to watch the short- and long-term changes that take place on the comet, helping to answer some of the biggest and most important questions regarding the history of our Solar System. How did it form and evolve? How do comets work? What role did comets play in the evolution of the planets, of water on the Earth, and perhaps even of life on our home world?
“The data collected by Philae and Rosetta is set to make this mission a game-changer in cometary science,” said Matt Taylor, ESA's Rosetta project scientist.