When the Philae lander reached the comet 67P/Churyumov-Gerasimenko after a decade in space, the ESA expected it to draw energy from the sun to power its scientific instruments. Unfortunately, it's now stuck in the worst place possible: in the shade, where it's exposed to the sun only three hours per day. According to the probe's lead scientist Jean-Pierre Bibring: "We are exactly below a cliff, so we are in a shadow permanently." In order for the lander to continue collecting samples and crunching data to beam back to Rosetta, it needs at least six to seven hours of daily sunlight. It's been sniffing and analyzing molecules from the comet's surface thus far, but once its main batteries run out on Saturday (they can only power the lander for 64 hours from the time it separated from Rosetta), it'll have to lay in hibernation unless its situation somehow improves.
The agency designed the lander to keep it from bouncing, but that still what happened. Philae's harpoons apparently failed to deploy and to secure it to the ground, so it bounced twice before landing with one foot in the air, a kilometer away from the intended landing site, at either the opening of a cave or right next to a boulder. At the moment, the ESA can't perform any drilling, as the washing-machine-sized equipment is on its side and could topple over. It can't deploy the harpoons either, since gravity on the comet is 100,000 weaker than on Earth's, so the movement could send Philae flying back into space.
Here's what ESA plans to do, though: it will activate one of Philae's moving instruments, which could shift it slightly where it can harness more sunlight. After that, the agency will position Rosetta above the comet to take pictures and pinpoint the probe's exact location. Once the scientists have a better idea of where the lander is, they can then decide what to do next. But if the ESA really can't do anything before the batteries die, the agency will just have to wait it out: the comet's slated to pass near the sun in the coming months, where the lander might have better access to sunlight.
[Image credit: ESA]