A mosaic of images from Rosetta's OSIRIS camera show Philae's descent

Gas jets could revive Rosetta comet probe

Europe’s hibernating Philae comet lander could be revived if gas jets launch it back into sunlight where solar panels could recharge its batteries.

The European Space Agency (Esa) probe landed on the surface of Comet 67P/Churyumov-Gerasimenko after being released by the orbiting Rosetta mothership last Thursday, but went into ‘idle mode’ on Saturday after its primary battery ran out of power.

The craft is equipped with solar panels designed to charge a secondary battery, but it bounced off the comet's surface during landing after harpoons designed to anchor it to the surface failed, causing it to miss its intended landing zone and end up in the shadows of a cliff where it is not getting the sunlight needed to power back up.

But the comet is heading towards the Sun and as the increasing sunlight warms the lander's host it will release jets of gas, which could potentially lift Philae of the surface and reposition it somewhere that receives more sunlight.

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 so even a small jet of gas could lift it fairly easily.

"It could be a natural way that it gets lifted up," former Rosetta manager Gerhard Schwehm said at a teleconferenced Nasa science advisory panel meeting in Washington DC. "If a little activity starts there, then the chance that it comes off is fairly high."

Pictures from a camera aboard Rosetta released by Esa yesterday have captured the final minutes of Philae's descent, bounce and drift across the comet's face.

The comet's surface was harder than scientists originally thought, which is partly why its harpooning landing system failed, but Schwehm said this 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," he said.

The 57-hour life of the lander’s primary battery was enough to carry out the entirety of the mission’s first science sequence and radio the results back to Earth.

Early results from the ongoing Rosetta mission are expected to be released next month at the American Geophysical Union Conference in San Francisco.

Before shutting down, Philae shifted its position to try to catch more light on one of its solar-powered panels so that it can power back up for an extended mission.

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