Philae update

Comet lander starts drilling but batteries a worry

By GEIR MOULSON

Good news: the spacecraft that landed on a comet has begun drilling below the surface to see what secrets the celestial body can reveal.

Bad news: Scientists at the European Space Agency that launched the historic mission still don't know exactly where the lander is on the comet and were anxiously hoping its batteries will keep running long enough to get the mining data and adjust the lander's position.

It was a race against time Friday for the Philae lander, which on Wednesday became the first spacecraft to touch down on a comet. Since then it has sent astonishing images from the icy, dusty comet named 67P/Churyumov-Gerasimenko and generated some data from onboard instruments such as one that measures temperatures. All this is taking place 311 million miles (500 million kilometers) from Earth on a comet traveling 41,000 mph (66,000 kph) through space.

Material beneath the surface of the comet has remained almost unchanged for 4.5 billion years — making those mining samples a cosmic time capsule that scientists are eager to study. Mission controllers said Philae was able to bore 25 centimeters (10 inches) into the comet's surface to start collecting the samples, but it's unclear whether it has enough power to be able to deliver any information on them.

The lander has an estimated 64 hours of battery power and solar panels to generate power after that. Scientists hope the batteries will still have some power next time it's due to make contact late Friday night. The agency said it would provide an update on that over the weekend.

Scientists hope the $1.6 billion (1.3 billion-euro) project launched a decade ago will help them better understand comets and other celestial objects, as well as possibly answer questions about the origins of life on Earth.

Philae bounced twice on the comet before coming to rest Wednesday after two harpoons that should have anchored it to the surface failed to deploy. Controllers still haven't been able to pinpoint its position, but photos indicate it's next to a cliff that is largely blocking sunlight from reaching two of its three solar panels. It hasn't moved since.

"Maybe the battery will be empty before we contact again," Stephan Ulamec, head of operations for Philae, said in a briefing.

If the batteries are still running and scientists can extract the scientific data from the craft, "we plan to rotate the lander a little bit" so that a bigger solar panel gets some sun than the one currently in that position.

"That would increase the chance that, at a later stage, the lander could wake up again and start talking to us again," he said.

After the batteries run out, Philae will remain on the comet in a hibernation mode for the coming months. The comet is on a 6 1/2-year elliptical orbit around the sun that at the moment is getting closer to it. So, in theory, Philae could wake up again if the comet passes the sun in such a way that its solar panels catch more light.

Meanwhile, the Rosetta orbiter — Philae's mother ship, which is streaking through space in tandem with the comet — will also use its 11 instruments to analyze the comet over the coming months.

No matter how long Philae keeps talking to them, scientists say they already have gathered huge amounts of data and are calling the first-ever comet landing expedition a roaring success.

Valentina Lommatsch at the lander control center said she was "extremely happy with how the mission went."
"We juggled everything so that every instrument got a chance to do a measurement," she said.

"Let's stop looking at things that we could have done if everything had worked properly," added flight directorAndrea Accomazzo. "Let us look at things that we have done: what we have achieved and what we have on the ground. This is unique and will be unique forever."

Accomazzo said he'd still like to know where Philae is on the comet. Communication with the lander is slow, with signals taking more than 28 minutes to travel between Earth and Rosetta.

Holger Sierks, the principal investigator for the Rosetta's camera systems, said cameras should have caught "the rebound and the rebound direction, which will give valuable information to the search team."

That data has not yet come in, however. Specialists still need to comb an area between one and two square kilometers (0.4 and 0.8 sq. miles) on the comet to find Philae.