Time is quickly running out for the Philae lander. With insufficient exposure to sunlight, the probe cannot recharge its battery, forcing ESA mission controllers to take desperate actions that could further destabilize the lander.

Top image: Comet 67P/Churyumov–Gerasimenko at less than 40 meters from the surface.

The three-legged robot is in quite a pickle right now. Philae is resting in the shadow of a cliff, wedged in and tipped up on its side. One leg is dangling in space. Its solar panels are only receiving 1.5 hours of light per day (as opposed to the planned six to seven hours), which is not nearly enough to recharge its 60-hour battery. Given the predicament, caution has turned to desperation at the European Space Agency. Controllers are now trying to get the most out of the probe before it blinks out, possibly in less than 24 hours.

An illustration of Philae's current predicament. It landed nearly vertically on its side with one leg up in outer space. It's shown in relation to the panoramic photos taken with the CIVA cameras.

Earlier today, Philae lowered an X-ray instrument to the surface, and a hollow rod designed to measure thermal and mechanical properties was hammered into the surface.

Controllers have issued commands to the probe to drill into the subsurface. This is considered a very high risk manoeuvre as the ensuing kinetic energy could further destabilize the probe and even send it back into space. Should it work, the drill would feed a sample to two gas experiments.

And in an effort to prolong the mission, ESA controllers are also considering rotating the solar panels into a better position. If it works, it could eke out a few more hours of life for the lander.

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They're even considering another hop, using the lander's springy legs — and then hoping for the best. But according to this tweet, harpoons are not an option:

Mission controllers are also desperately trying to find out where the lander is resting on the comet. It bounced twice during the procedure, including a one-kilometer bounce that temporarily sent it back into space.

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"We're coming to the end so we're taking more risks. But we're super happy with what we've done up until now. I can't tell you exactly how much this lander has achieved but it is close to 100%," said Paolo Ferri, the head of mission operations at ESA's command center in Darmstadt, Germany. "What's missing is the drilling. But with time running out, we're taking risks."

Indeed, despite these unexpected setbacks, the mission must be considered a huge success. The ESA was successful in landing a probe on a comet, even if its orientation is not ideal. What's more, its 10 instruments are currently pulling in reams of invaluable data that scientists back on Earth will be studying for years to come.

[ BBC | ScienceInsider ]

Images: ESA.