On Thursday, the team published a massive collection of data acquired by the lander in the journal Science, but it seems likely that these will be the intrepid robot's last scientific contributions.
Reuters reports that Philae hasn't been in contact since July 9 (with that being the first contact since June 24), and that its parent orbiter Rosetta won't be in the right position to speak to it again until August -- just as comet 67P/Churyumov-Gerasimenko makes its closest approach to the sun.
“It’s a bit frustrating to have an apparently working lander on a comet surface and not being able to communicate with it,” Philae lander manager Stephan Ulamec told Science magazine.
The extra light from the sun's proximity is what allowed Philae to wake up: When the lander touched down, it bounced several times and landed askew in a shaded area, limiting its ability to charge its batteries and continue operating. The comet's summer sun gave Philae a boost, allowing it to operate normally when it would have been overheated in its intended landing spot.
But scientists now worry that Philae shifted yet again during its second leg of operations. Even if the closest approach to the sun gives Philae enough light again, there's no telling if or when it will be exposed to too much heat and give up the ghost for good. And in September or October, the comet will become too dark, closing the window of opportunity.
So the scientific goodies published on Thursday may represent the bulk of Philae's findings. The Rosetta orbiter is sure to find out more about 67P in the coming weeks -- the comet is becoming more and more active as it approaches the sun, and all of that melting and off-gassing is going to expose molecules locked away since the birth of our solar system -- but the orbiter may have to do without its little helper, especially since those gasses will make it dangerous for the orbiter to come very close.
What science did little Philae do during its short tenure? One of its most interesting finds came courtesy of the bumpy landing that put it out of commission.
When Philae landed, it bounced off of the intended landing surface -- which was soft -- and onto the edge of a crater, where the surface was significantly harder. This gave the team its first real-world look at the variation in the comet's surface. They now believe the comet has a thin, crusty layer beneath its dusty surface.
Another of the seven published studies focuses on results gathered by shooting radio waves through the comet while Philae and Rosetta were on opposite sides of it. By analyzing these waves, the team was able to measure the composition of 67P's interior -- and they found a lot of empty space inside of it.
Around 85 percent of the comet's interior is empty, according to the electromagnetic data, indicating that the comet is incredibly porous. Other data suggests that the interior is surprisingly uniform.
Yet another study reports four organic molecules previously not known to exist on comets: methyl isocyanate, acetone, propionaldehyde and acetamide. The chemistry of 67P is incredibly important, as scientists hope to learn about the molecules present at the birth of the solar system by figuring out what comets are made out of.
It's going to take more time with Rosetta -- and more time with the data itself -- to really put together a clear picture of what comets are like and how they formed. This mission may not even answer most of the questions scientists have, and we'll have to visit more comets if we want any hope of understanding them. But one thing is clear: Even if Philae's days of doing science are done, it did good.