Caitlin: Philae, we hardly knew ye! We don't know if it's dead, or asleep, of if we'll ever find out everything that it learned during its short mission. But we do know that Philae, the first spacecraft ever to land on a comet, is lost to us. At least for now.

It took ten years and over six billion kilometers for it to reach its target, the comet 67P, or Churyumov-Gerasimenko, and then when Philae finally arrived at its destination, it bounced. Twice. At just three kilometers wide, the comet doesn't have enough gravitation to hold the lander in place. So Philae's designers at the European Space Agency equipped it with harpoons that would deploy upon contact to anchor it to the surface. But for reasons that elude the ESA, they never fired. As a result, the lander bounced off the surface of the comet and landed about a kilometer away from its intended site, which had been chose so that the lander would be exposed to enough sunlight to power its batteries. After it bounced again, Philae found itself in the dark.

The first sign of trouble was this: the first-ever photograph captured from the surface of a comet. Taken by Philae's Shiva camera array, the image shows the lander in the shadow of a cliff, or maybe inside a chasm. After checking data from Philae's solar panels, the ESA confirmed that the lander wasn't getting enough sunlight. Instead of the six to seven hours of exposure that the probe needed to keep running, one of its solar panels was only getting an hour and twenty minutes of sun during each of the comet's twelve-hour rotations, while its other two panels were getting about twenty minutes. With such meager exposure, researchers predicted that their lander would run out of batteries sometime on Saturday, and they were right. Despite a last-ditch effort to reposition the probe so it could get a bit more light, Mission Control finally lost contact with Philae on Saturday at 00:36 UTC.

But Philae is not dead, exactly. All it needs is more sunlight to be up and running again. Researchers hope that sometime over the next nine months as comet 67P draws nearer to the sun, it may start to get enough light to charge Philae and awaken it from its slumber. Since they don't know exactly where the lander is, they don't know how likely this will be. But for now, researchers are focusing on all of the data that the probe managed to collect in its final hours. As soon as mission controllers realized time was running short, they activated all of its scientific instruments, including one called MUPUS, which tested physical properties of the comet's surface, and another, APXS, which tested its elemental composition. They were able to get almost 65 hours of data from each. The results of this data, which are now being analyzed, will be presented next month. So no matter what else happens to the lander, it will have provided us with out first intimate look at a comet, a relic of debris from the formation of our solar system.

Before nodding off, Philae was also able to take the first-ever drill sample from the surface of a comet, as well as loads of great images. These images, paired with images taken by Philae's mother ship, the Rosetta orbiter, may help researchers piece together exactly where Philae has ended up. As Rosetta continues to orbit 67P at a distance of thirty kilometers, and then closing in to twenty kilometers in December, its pictures and measurements will hopefully give clues as to where the lander came to rest. This will help Mission Control predict whether the lander will wake up again and when.

Meanwhile in the coming months, Rosetta will start a series of unbound orbits, passing the comet at a variety of distances, some less than eight kilometers from its center, and tracking the changes that occur as 67P approaches the sun, adding to its already long list of data on these astronomical objects.

So don't give up hope, comet lovers! We haven't heard the last from this mission. And thank you for joining me for SciShow Space News, which was brought to you in part by lynda.com, which as you probably know, is a leading online learning company that helps anyone learn software, technology, creative, and business skills to achieve personal and professional goals. Basically, it helps you learn how to make videos, so if you're interested, go to lynda.com/space and check it out.

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