Philae has woken up after seven months of hibernation

Comet-lander awakes after months of hibernation

European space scientists had a reason to celebrate this weekend as they received data from the Philae comet lander feared dead seven months ago.

The lander, which travelled to the distant Comet 67P/Churyumov-Gerasimenko aboard the Rosetta spacecraft during a decade-long journey, was the first ever man-made object to touch down on a cometary surface.

However, the historic achievement turned sour after the researchers found that instead of anchoring itself firmly to the selected landing spot, the lander bounced off several times and came to rest in a totally wrong place.

The accident was caused by the lander’s harpoons failing to deploy. The lander found itself shaded by a cliff with no direct view of the Sun. As a result, it wasn’t able to recharge its batteries with the help of solar panels and went dormant when its primary battery was depleted after only two days of operations.

As the comet moved closer to the Sun, Philae has been able to gather some power from the solar rays and talk to its controllers back on Earth.

"Philae is doing very well: It has an operating temperature of -35ºC and has 24 Watts available," explained Stephan Ulamec, project manager of the Philae project at the German Aerospace Agency (DLR). "The lander is ready for operations."

The signals were received by the European Space Operations Centre in Darmstadt, Germany on Saturday 13 June at 22:28 CEST.

The contact lasted for about 85 seconds, during which Philae managed to transmit 300 data packets. To enable the transmission, Philae needs to first align with the Rosetta probe, in orbit around the comet at about 6.5km. Rosetta then relays the data to Earth.

"We have also received historical data – so far, however, the lander had not been able to contact us earlier," Ulmanec remarked.

Now the scientists are waiting for the next contact. There are still more than 8000 data packets in Philae’s mass memory which will give the DLR team information on what happened to the lander in the past few days.

The scientists hoped the lander would wake up as the comet moved nearer to the Sun and had turned on the communication unit on the Rosetta orbiter three months ago.

During its primary two-day mission, Philae drilled into the surface of the 3km by 5km comet, analysing the ancient material it consists of.

Scientists said the data will provide them with a window into the past and allow them to develop better understanding of the origins of our universe. Comets, made of a mixture of ice and rock, conserve ancient organic molecules and chemicals present in the earliest stages of the universe.

"Comets are treasure chests of material from the birth of the solar system," said Mark McCaughrean, senior science advisor at the European Space Agency (Esa).

Scientists must now race to extract as much data from the comet as possible before its orbit takes it back away from the Sun in several months' time and towards the outer reaches of the solar system.

At that point, the mother ship Rosetta will have burned most of its fuel. Unable to manoeuvre, scientists are likely to let it spiral slowly towards the comet's surface, making an increasingly detailed analysis from above until it comes to rest and loses contact with the Earth. 

The entire Rosetta mission cost close to €1.4bn.

 

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