While the Rosetta orbiter that dropped Philae has continued to analyze comet 67P/Churyumov-Gerasimenko, the mission team has periodically tried to rouse the sleeping lander. The increase in light as comet 67P approached the sun allowed Philae to phone home in June and July, but it's been silent ever since.
Now the mission is at a critical turning point – and Philae may truly be lost for good.
"With every passing day, Comet 67P/Churyumov-Gerasimenko is getting further and further away from the Sun, and as such, temperatures are falling on the comet's surface," the ESA wrote in a statement. "Things are getting critical for Philae: conditions are predicted to be “lander-hostile” – too cold – by the end of January."
When Philae made contact over the summer, the team expressed concern that the lander might have shifted yet again, preventing it from taking advantage of the increased sunlight.
On Sunday, the team sent a signal to Philae's momentum wheel, which stabilized it during its landing, in the hopes that it might shift the lander into a better position – or at least shake some dust off of its solar panels.
The control team reported on Twitter that Sunday's attempt had failed:
The team will make twice-daily attempts throughout the month, and the Rosetta orbiter will keep an ear out for Philae for as long as the spacecraft is operational. But by the end of January, the comet and its robotic companions will be more than 480 million miles from the sun, which will drop Philae's operating temperature to around -60 degrees Fahrenheit. With conditions that hostile and with less sunlight reaching the comet every day, the lander isn't expected to rally in the spring.
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