Comet probe loses power, but mission not over yet: ESA

Although the comet probe lander Philae ran out of juice, there’s still hope that the sun will help revive the mission in the months to come.

Gas jets from inside the comet hosting Europe’s Philae lander may launch the hibernating probe out of its ditch and back into sunlight for a battery recharge, a former mission manager reassured observers whose enthusiasm may have been deflated when the probe’s landing didn’t go quite as planned.

The washing machine-sized spacecraft, Philae, built by the European Space Agency (ESA) ended up in a ditch after bouncing off the comet’s surface, after it was released by its orbiting Rosetta mother ship on Nov 13. On Nov 15, Philae wrapped up an unprecedented 57-hour mission on the surface of Comet 67P/Churyumov–Gerasimenko, before its battery reserves died.

A camera aboard Rosetta, which flew less than 16km above the comet’s surface, captured the final minutes of Philae’s descent, bounce and drift across the comet’s face – all revealed in photos released by ESA.

Stuck in a rut: Above, a mosaic of a series of images captured by Rosetta’s OSIRIS camera over a 30 minute period shows Philae not-so-smooth descent onto the 67P/Churyumov-Gerasimenko comet's surface. Below, Philae is seen in its final landing place.  – Reuters

The unintended bounce – a result of Philae’s harpooning ice screws failing to anchor onto the surface – left the lander in a ditch, shielded from the light of the sun it needs to charge its battery for an extended mission.

Scientists anxiously waited as Philae hustled through an automated series of experiments – including drilling in the comet’s body – and, against the odds, survived long enough to radio results back to Earth. Before shutting down, Philae shifted its position to try to catch more light on one of its solar-powered panels, but no luck – for now, that is.

But scientists hope, that as the comet, nicknamed 67P, gets closer to the sun, accompanied by the orbiting Rosetta satellite, that the increasing amount of light will not only charge the probe’s batteries but, with the release of jets of gas as the comet itself warms up, potentially hoist Philae out of its ditch.

“It could be a natural way that it gets lifted up,” says former Rosetta manager Gerhard Schwehm during a teleconferenced NASA science advisory panel meeting in Washington, D.C. “If a little activity starts there, then the chance that it comes off is fairly high.” Gravity on the comet’s small body is about 100,000 times less than Earth’s, giving Philae the relative weight of a piece of paper.

The comet’s surface was harder than scientists originally thought, which is partly why its harpooning landing system failed. However, Schwehm says that may have been a blessing in disguise. “Perhaps it was good that (Philae) didn’t fire the harpoons because if they would not have penetrated you might have had a much bigger problem.”

Early results from the ongoing Rosetta mission are expected to be released in December at the American Geophysical Union conference in San Francisco. – Reuters