On Sept. 2, 2016, the European Space Agency finally located Philae, its long-lost comet lander. Philae was a spacecraft about the size of a washing machine, and it was dropped off at Comet 67P by another spacecraft named Rosetta in November 2014.
But when Philae's landing harpoons failed to deploy, it bounced all over the comet before tumbling into a shady place where its solar panels couldn't collect enough light. Philae did transmit some data to Rosetta while using the last of its batteries after the landing, and it occasionally made contact for months after the crash.
Rosetta kept looking for Philae by flying around Comet 67P and taking photos. It took Rosetta almost two years to find Philae. A photo taken on Sept. 2, 2016 showed little Philae lying on its side in a dark, rocky crevice.
Why it mattered
Locating Philae's grave finally gave the European Space Agency some closure less than a month before Rosetta's mission came to an end with an epic crash landing on Comet 67/P.
The European Space Agency's Rosetta mission was an ambitious project. It was the first mission ever to successfully land a probe on the surface of a comet to understand how the icy objects change as they travel through the solar system (although, NASA's Deep Impact mission did intentionally crash into a comet on July 4, 2005, it did not make soft, controlled landing).
The moment of truth occured on Nov. 12, 2014, when Philae touched down on the surface of Comet 67P/Churyumov-Gerasimenko (we'll call it 67P for short) after a day-long descent that some scientists had dubbed the "seven hours of terror."
While Philae succeeded in its attempt to make the first-ever soft landing on a comet (Philae actually landed 3 times after bouncing twice), and even snapped photos of the surface, its exact location was unknown. Philae failed to fire a set of harpoons to anchor it into the surface of Comet 67P, and while Rosetta did manage to track the lander after its first bounce, it lost track shortly thereafter.
Philae was a solar-powered lander, equipped with a suite of 10 instruments (and even a drill) to study comet 67P up close. But because it ultimated ended up in a shadowy crevasse on its side, it couldn't generate the power needed for prolonged science observations. Its onboard batteries ran out after just 60 hours. But despite that truncated lifetime, Philae made several key discoveries – including detecting organics on 67P, mission scientists said.
Fortunately, the Rosetta mission team had plenty of time to search for Philae.
Rosetta circled comet 67P for another 22 months, snapping more than 80,000 images in all as it studied the icy object while also searching for Philae. By luck, Rosetta managed to find Philae just weeks before its mission ended with its own landing on the comet on Sept. 30, 2014.
