Dwindling battery makes comet drill results uncertain

BERLIN: Robot lab Philae drilled into its host comet Friday with just hours of battery left, but may lose power before it can transmit results of a much-anticipated attempt to probe below the surface, mission scientists said.
Charged with 60 hours of onboard power, the lander bounced twice after initial touchdown Wednesday, settling at an angle in a crevice in an unknown location, shadowed from sunlight that could potentially have extended its battery life.
With its energy supply fast winding down lander manager Stephan Ulamec said the drill was “started” on Friday, but contact between Philae and its orbiting mothership Rosetta was lost soon thereafter.
The washing machine-sized craft is now resting in the shadow of a cliff on the celestial body.
One of the most important tasks for the 100-kg (220-pound) probe — dubbed Philae and weighing only 1 gram on the comet’s low gravity surface — was to drill into rock to analyze samples.
Comets are of interest to scientists because they constitute remnants from the formation of our solar system more than 4.6 billion years ago. These masses of ice and rock have preserved ancient organic molecules like a time capsule. Philae’s drill descended more than 25 centimeters (10 inches) on Friday but it was unclear whether it had penetrated the comet’s surface. The radio link between Rosetta and Philae has been interrupted as the spacecraft orbits.
“This will be exciting because we’re not sure if the batteries will have enough power to transmit this data,” said an expert.
Compounding problems caused by the lack of light reaching its solar panels, an ESA command for Philae to enter low power mode to maximize battery life did not get through.
The ESA team are looking at options to move the probe into a position where it could draw more light, such as using a flywheel to “hop” the craft out of the enclosure of rocks.
Another solution could be rotating its solar panels, which would not require moving Philae out of its current location.
But they will undertake such measures only if there proves to be enough battery power to transmit the drilling results.
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.
If Philae’s mission comes to an end on Friday, 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.
“This mission is fantastic, let’s look at what we have achieved, not at what we would have done differently. This is unique and will be unique forever,” said Andrea Accomazzo, the Rosetta flight director.