The European Rosetta spacecraft began to listen out for its robotic lander this morning amid hopes that the comet-riding probe may soon have enough solar power to wake from hibernation.
The Philae lander has not been heard from since its batteries ran out three days after its dramatic and bouncy landing on comet 67P/Churyumov-Gerasimenko in November.
The lander touched down on the comet exactly where mission controllers had planned, but when anchoring harpoons failed to fire, Philae bounced off the surface twice and finally came to a rest against a cliff face that cast a shadow over its solar panels.
Hibernation
Unable to recharge its batteries, Philae went into hibernation. But as the comet speeds towards the sun, mission controllers hope that the probe might receive enough sunlight to awaken and call its orbiting mothership.
In the early hours of Friday morning, scientists at the European Space Agency switched on Rosetta’s receivers in case the probe stirs to life in the coming days. Until May 17, the lander will be in sunlight twice a day when the Rosetta spacecraft is overhead and able to pick up its signals.
“It’s almost certainly still too cold for Philae to recharge its batteries, but it may be able to make contact during the short time it is illuminated twice a day,” Stephan Ulamec, the Philae lander manager, told the Guardian. The rotation of the comet means that Philae has an hour and twenty minutes of sunlight twice a day during which it could call the orbiter.
Mission controllers tried without success to contact Philae in March and April, but the lander was getting so little sunlight that the odds of Philae rousing from its sleep were low.
“In May we now start to have a good chance of making contact, and in June it will be even better. As we get closer and closer to the sun we hope the lander will get more and more power,” Ulamec said. The chances of Philae recharging its batteries will rise until mid—August when the comet passes closest to the sun before speeding back out into the darkness of the distant solar system.
The electronics onboard Philae need to be warmer than —45 Celsius to operate properly, but they may still be too chilly to work, Ulamec said. After 17 May, Rosetta will fall out of position to communicate with Philae until the end of the month, or later in June.
— © Guardian Newspapers Limited, 2015
