Shaded landing site could spell doom for comet probe’s solar batteries

European Space Agency scientists on Friday decided to begin a risky drilling procedure to enable an exploration lander to examine samples from the surface of a comet before its batteries run out.

The lander, released by the Rosetta spacecraft on Wednesday after a 10-year odyssey 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 of its three legs in the shadow of a cliff.

The lack of light means that after its batteries run out later on Friday, the lander, Philae, will not draw sufficient energy to operate on its solar panels as hoped. European scientists with the ESA are uncertain of the probe’s exact position on the comet, making it difficult to hop it into a better position using its landing gear.

The 220-pound probe — virtually weightless on the comet’s surface — was supposed to drill into the surface of the comet after landing, but its unstable position and the comet’s weak gravitational pull made the scientists fear that deploying the drill would bounce Philae off the comet.

But with the probe’s 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. They also said they were working on ways to enable Philae to collect more energy and keep working. They could rotate the main body of the lander to give its solar panels better exposure to the sun, for example.

Mission controllers said Friday that Philae had commenced drilling, though it was unclear whether it would succeed in collecting samples. Stephan Ulamec, head of operations for Philae, said controllers haven't yet been able to identify precisely where on the comet Philae is.

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.

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.

Even if Philae is unable to drill into the surface to analyze the comet’s composition, the Rosetta spacecraft will follow the comet until at least the end of 2015.  

Wire services