Scientists at the European Space Agency will this week start listening out for signs that a small dishwasher sized lander, dropped onto the surface of a comet last year, has woken up.
On 12 November last year Philae landed on Comet 67P/Churyumov-Gerasimenko, which at the time was located 500km from Earth.
But it bounced into an unplanned final resting place against the side of some cliffs.
The new landing site left Philae partially in shadow, and therefore unable to generate power through its solar panels in order to recharge its batteries.
As a result, the lander shut down and was unable to continue sending back readings and measurements of its new icy and dusty surroundings.
At the time, scientists expressed the hope that as the comet raced towards the Sun it might be able to gather enough energy to wake up, start communicating with its Rosetta mothership and once again resume its experiments.
Scientists at the German space agency, DLR, who are involved in controlling the lander, say this week presents the first possibility of receiving a signal from Philae.
As a result, the communication unit on Rosetta will be turned back on again on Thursday to call the lander, and will continue listening for a response until 20 March.
"Philae currently receives about twice as much solar energy as it did in November last year," said Lander Project Manager Stephan Ulamec from the German Aerospace Center in a blog post.
"It will probably still be too cold for the lander to wake up, but it is worth trying. The prospects will improve with each passing day."
The comet, Rosetta and Philae are currently situated 320km from the Sun.
The scientists say that several conditions will have to be met before Philae will start operating, including that its internal temperature must reach -45C and it must be able to generate at least 5.5 watts of solar power in order to start recharging its battery.
Once awakened, the scientists say, Philae switches on its receiver every 30 minutes and listens for a signal from the Rosetta orbiter. It must then also be able to transmit a signal back to Rosetta.
The lander team says it is possible that Philae has already woken, but has not yet generated enough power to send and receive signals to and from Rosetta.
The most likely opportunity for a signal to be received, they say, is during 11 flybys where the orbiter is in a favourable position with respect to the lander and the sunlight is shining on the location where the lander is thought to be.
The scientists say the ability to carry out the planned programme of scientific work using the ten instruments on board Philae will depend on results sent back by the lander about its state of health, assuming it wakes up.
