Philae goes dark again, just as comet starts coming apart in the Sun

The emotional roller-coaster continues — researchers at the European Space Agency (ESA) have lost contact with the comet lander Philae once again. Scientists haven’t heard anything from the intrepid explorer since July 9, and they now fear the probe has shifted in place, potentially damaging it or further blocking its solar panels from absorbing sunlight. With the comet changing rapidly as it approaches the Sun, it’s entirely possible that this is the end of the road for the incredible little ESA lander — but then again, Philae has been in similar situations before. Don’t count the little lander out just yet.
Philae communicates with the Earth via the nearby Rosetta spacecraft, which carried it to its destination. The geometry of line-of-sight communication means that Rosetta can only hear from Philae some of the time — so when the lander fails to check in during a pre-scheduled communications window, it’s a big deal. This is how Philae’s handlers control it, collect its readings, and direct it into ever-better situations for prolonged use. If they can’t establish contact to tell Philae how to get back into position for power generation and communication, then even a tiny problem could remain unfixed forever.

This 360 degree panorama taken by Philae shows that the little lander ended up in an awkward spot.

Philae’s problems started upon its first landing — it bounced out of the landing zone, and ended up on a tilted plane in a largely shaded area. It couldn’t properly unfold its top panels to expose the electricity-generating solar panels there, and there was little sunlight to expose them to in any case. Despite some intermittent contact with the lander, though, scientists could see that the batteries were too depleted for Philae to be able to carry out its mission. Rather than risking a total loss of power, they shifted it into hibernation mode until the comet moved closer to the sun, and potentially exposed the landing site to a usable amount of sunlight.
While the researchers had thought that Comet 67P/Churyumov-Gerasimenko might not reach that point until August or later, they were able to reestablish contact in June. Things looked promising, and they had the lander rotate and raise itself a bit to better face the Sun — but it now seems that the efforts won’t pay off long-term. The June connection allowed Philae to transmit some extra data, potentially very important in nature, but with the latest blackout chances of a continuing mission dwindled further than ever.

Comet 67P/Churyumov-Gerasimenko is nearing the most active period of its orbit.

One issue is that one of Philae’s two transmitters seems to be broken, and the ESA is currently struggling to get the lander to communicate using only the one that remains operational — but doing so would require some ability to communicate, which they currently do not have. The ESA admitted in a statement Monday that the lack of sunlight “does not seem to be explained by the course of the seasons on the comet alone.” This means that the lander itself has likely shifted position in an unforeseen way, which means that it could be in virtually any position at all.
While astronomers are still hopeful they could reestablish contact (again, it’s happened before), they must also face the reality that there’s no particular reason to think that will happen. They hope to get even a tiny window of connectivity, to quickly pull out any last data from measurements already taken.

Source: ESA.

Rosetta will now  orbit further out from the Comet 67P, to avoid being hit by any stray particles released by increased “activity” on the surface — that is, the heat from the approaching sun melting comet’s icy body and causing it to slowly come apart. The increased debris and distance mean communication will be even more difficult than usual, and the ESA has shifted the main focus of the scientific project to the Rosetta orbiter.
They will keep trying to reestablish the connection, however. Even the tiniest bit of data is worth investment, when it’s collected by a robot on a comet.