Philae goes silent amid wait to see if comet nudge can deliver sunlight

The pioneering comet lander Philae remained silent Saturday, sending out no signs of life during a scheduled effort to establish communication, the head of the European Space Agency (ESA) said.

Paolo Ferri, ESA's head of mission operations, said that the Rosetta orbiter — from which Philae made its descent — did not receive any signals from the lander. It has sparked fears that having run out of power and with no certainty of being able to recharge, the brief dalliance with a comet may have come to an end.

Scientists involved in the mission put a brave face on events, noting that Philae completed its primary mission and had sent reams of data, including photos, back to earth. And there is a chance that the lander could spring back to life.

On Friday, the ESA performed a rotating operation to pull Philae out of a shadow so that solar panels could recharge the depleted batteries. Even if that operation was ultimately successful, it may take days or weeks until the batteries of Philae are strong enough to send signals again.

"We don't know if the charge will ever be high enough to operate the lander again," Ferri.

On Wednesday, Philae landed next to a cliff that largely blocked sunlight from reaching its solar panels.

The historic landing was the climax of a 10-year journey aboard the Rosetta space probe. Since alighting on the comet, some 311 million miles distant from Earth, the lander has performed a series of tests and sent back information being analyzed back on Earth.

The spacecraft on Friday was given commands to rotate itself to catch more sunlight and to drill a hole into the comet. But Ferri said Saturday that "we know that all the movements of the operation were performed and all the data was sent down.” 

"However, at this point we do not even know if it really succeeded and if it (the drill) even touched the ground during the drilling operation,” he said.

Material beneath the surface of the comet has remained almost unchanged for 4.5 billion years, so the samples would be a cosmic time capsule that scientists are eager to study.

Scientists hope the $1.6 billion project will help answer questions about the origins of the universe and life on Earth. Communication with the lander has been slow, with signals taking more than 28 minutes to travel between Earth and Rosetta. But Scientists say they already have gathered huge amounts of data and are calling the first-ever comet landing a roaring success.

Comets are pristine remnants from the formation of our solar system some 4.6 billion years ago. They contain rock and ice that have preserved ancient organic molecules like a time capsule and may provide insight into how the planets and life evolved. 

Philae's drill descended more than 10 inches on Friday, penetrating the comet's surface. Previous robotic probes conducted brief fly-bys. Rosetta arrived at comet 67P/Churyumov-Gerasimenko in August for a mission that is expected to run at least through December 2015. 

“This mission is fantastic, let's look at what we have achieved, not at what we would have done differently,” Rosetta flight director Andrea Accomazzo said Friday, adding: “This is unique and will be unique forever.”

Al Jazeera and wire services