European scientists face decisions as comet probe batteries run down

[November 14, 2014]  BERLIN (Reuters) - European Space Agency scientists will on Friday decide whether to try a risky drilling procedure to enable an exploration probe to examine samples from the surface of a comet before its batteries run out.

The probe, released by the Rosetta spacecraft on Wednesday after a 10-year odyssey 500 million km (300 million miles) from Earth, floated away from its planned landing site after harpoons designed to hold it down on the comet failed to deploy.

It is now resting precariously on two out of three legs in the shadow of a cliff on the comet.

The lack of light means the probe, dubbed Philae, would not draw sufficient energy to operate on its solar panels as hoped once its batteries run out later on Friday. The ESA team are also uncertain of its exact position, making it difficult to "hop" the probe into a better position using its landing gear.

The 100-kg (220-pound) probe - virtually weightless on the comet's surface - was supposed to drill into the surface of the celestial body after landing, but its unstable position and the comet's weak gravitational pull means there is a risk it could bounce off if the drill is deployed.

But with the batteries about to run out, scientists at the ESA's operations center in Darmstadt, Germany told the BBC on Friday that it was time to take more risks with the probe. The ESA will give a mission update at 0800 ET.

They also said they were working on ways to enable Philae to collect more energy and keep on working, with one possibility being they could rotate the main body of the probe to give its solar panels better exposure to the sun.

Despite the landing setbacks, the mission has achieved many breakthroughs, including the first time a spacecraft has followed a comet rather than just whizzing past and the first time a probe has landed on a comet.

Comets are of interest to scientists because they are remnants from the formation of our solar system, over 4.6 billion years ago. These masses of ice and rock have preserved ancient organic molecules like a time capsule and may provide insight into how planets and life evolved.

Even if Philae is unable to drill into the surface to analyze samples, the Rosetta spacecraft will follow the comet until at least the end of 2015, even as it passes closest to the sun on its orbit.

(Reporting by Victoria Bryan; Editing by Mark Heinrich)

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