Data transmitted by the lander told scientists that its harpoons failed to engage, leading it to bounce off the comet's surface twice before coming to a rest about a kilometer from the landing site.
They're still not sure exactly where Philae is, but today, European Space Agency scientists did release a series of high-resolution images of the landing and subsequent bounce.
This composite image, captured by the Rosetta orbiter, shows the tiny lander's locations above the comet for about 30 minutes prior to its landing, as well as its location a moment afterward. You can see the slight disturbances created by Philae at the touchdown point (at top), as well as the outline of the lander off to the right just after it.
Due to the extremely low level of gravity on the comet, Philae's first bounce carried it as high as a kilometer above the surface. But the comet did have just enough gravity to pull it back, leading it to land again two hours later, then take another bounce before finally settling in a shadowy crater.
As a result, its solar panels were only able to collect about 90 minutes of sunlight every 12 hours, which meant the craft had to rely largely on its battery. Though ESA scientists used mechanical instruments on the craft to turn it slightly in hopes of getting more sunlight, the effort failed, and Philae powered down Friday evening (EST) after 57 hours on the comet.
Whats next for Philae
Even though Philae's landing didn't go perfectly, the mission as a whole was a huge success. During its brief time on the comet, the lander successfully used all ten of its scientific instruments and gathered all sorts of unprecedented data about its environment. It's estimated that the craft carried out roughly 80 percent of its planned science mission.
Although Philae was reportedly unsuccessful at drilling into the comet and extracting a rock sample, it was able to take photos, measure the temperature and density of the comet's surface, and send radar waves through the comet to analyze its interior. Crucially, in its final hours, it sent this valuable data up to Rosetta, which meant it could be relayed back to Earth.
Going forward, ESA scientists are going to scrutinize images taken by Rosetta in hopes of pinpointing Philae's location. They say it's quite possible that as the comet gradually nears the sun in the spring, the probe could be exposed to additional sunlight and wake back up. Knowing where the craft is and how it's positioned will give them a better idea of just how likely this might be.
Update: This post was edited to reflect the news that Philae was unable to extract a rock sample.