Now-silent lander finishes main tasks, space agency says

The pioneering lander Philae completed its primary mission of exploring the comet's surface and returned plenty of data before depleted batteries forced it to go silent, the European Space Agency said Saturday.

"All of our instruments could be operated, and now it's time to see what we got," ESA's blog quoted lander manager Stephan Ulamec as saying.

Since landing on Wednesday on comet 67P/Churyumov-Gerasimenko, about 500 million kilometers away, the lander has performed a series of scientific tests and sent reams of data, including photos, back to Earth.

In addition, the lander was lifted on Friday by about 4 cm and rotated about 35 degrees in an effort to pull it out of a shadow so that solar panels could recharge the depleted batteries, ESA's blog said.

ESA spokesman Bernard von Weyhe confirmed on Saturday the lander's difficult rotation operation. It's still unclear whether it succeeded in putting the solar panels out of the shade.

Even if the lander was rotated successfully and is able to recharge its batteries with sunlight, it may take weeks or months until it will send out new signals. Regular checks for signals will continue.

ESA's mission control center in Darmstadt, Germany, received the last signals from Philae on Saturday morning at 12:36 am GMT (8:36 am Beijing time). Before the signal died, the lander returned all of its housekeeping data as well as scientific data of its experiments on the surface - which means it completed the measures as planned, the ESA blog said.

During a scheduled listening effort on Saturday at 10 am GMT, ESA received no signals from Philae, ESA's mission chief Paolo Ferri said.

"We don't know if the charge will ever be high enough to operate the lander again," Ferri had said ahead of the 10 am GMT listening time. "It is highly unlikely that we will establish any kind of communication anytime soon."

Now it's up to ESA's team of scientists to evaluate the data and find out whether the experiments were successful - especially a complex operation on Friday in which the lander was given commands to drill a 25-cm hole into the comet and pull out a sample for analysis.

"We know that all the movements of the operation were performed and all the data was sent down" to ESA, Ferri said on Saturday. "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."