Rosetta's Philae Comet Lander Earns Rest After Completing Primary Science Mission

Rosetta's Philae lander has now officially completed its primary science mission after nearly 57 hours on a comet. Now, it's earned a well-deserved rest. Philae is now hibernating after its power was rapidly depleted.

"It has been a huge success, the whole team is delighted," said Stephan Ulamec, one of the researchers, in a news release. "Despite the unplanned series of three touchdowns, all of our instruments could be operated and now it's time to see what we've got."

Rosetta actually was out of communication ability with the lander on Friday, but then regained contact a few hours later. While the signal was initially intermittent, it quickly stabilized. During the time when the lander was in contact, it returned all of its housekeeping data in addition to science data from targeted instruments, including ROLIS, COSAC, Ptolemy, SD2 and CONSERT.

Yet perhaps most worrisome, at least at first, was that Philae's thruster wasn't properly functioning during the initial landing. This meant that the lander "bounced" when it landed. Despite the extra jostling, though, the lander functioned as planned.

Descent images show that the surface of the comet is covered by dust and debris ranging from mere millimeters to meters. In addition, panoramic images show layered walls of harder-looking material. Now, scientists are examining their data to see if they've sampled any of this material with Philae's drill.

Currently, Philae has powered down and is hibernating due to a lack of sunlight to continue its operations. However, the scientists hope that at a later stage of the mission, possibly when the comet nears the sun, there will be enough sunlight to generate enough power to wake up Philae.

Over the coming months, Rosetta will begin to fly in more distant "unbound" orbits while performing a series of flybys past the comet. This should allow researchers to watch short- and long-term changes that take place on the comet, answering questions about the history of our solar system.

"The data collected b Philae and Rosetta is set to make this mission a game-changer in cometary science," said Matt Taylor, ESA's project scientist.