57 hours after its landing on the comet 67P/G-C, the Philae lander has powered down after exhausting its battery life.
This happened a bit more quickly than planned, because Philae bounced twice after it landed, ending up in a shadowy crater, preventing its solar panels from much sunlight.
However, in terms of both scientific data and historical milestones, this mission was a huge success. In an extremely short time, the lander collected all sorts of information that will help us better understand the composition of comets. Additionally, the Rosetta orbiter will continue to orbit the comet for more than a year, collecting still more data.
Together, this research will help us better understand the solar system as a whole.
The latest news on Philae
When Philae landed, its harpoon system did not engage, leading the lander to take a few extremely long bounces, and ending up about a kilometer away from where scientists had planned. They're still not exactly sure of its location, but hope to use high-resolution photos taken by the Rosetta orbiter to pinpoint it soon.
Because the lander came to rest in a shadowy crater, 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).
However, during its 57 hours of life on the comet, the craft successfully used all ten of its scientific instruments and gathered all sorts of data about its environment.
Although Philae was reportedly unsuccessful at drilling into the comet and extracting a rock sample, instruments on the craft have taken photos, measured the temperature and density of the comet's surface, and sent radar waves through the comet to analyze its interior. All this data is entirely unprecedented — we've just never seen a comet up close before.
Additionally, scientists say that as the comet gradually nears the sun next year, it's possible the probe would be exposed to additional sunlight and wake back up, allowing for further investigations.
Finally, the key thing to remember is that the original plan called for 80 percent of the science of this mission to be carried out by the Rosetta orbiter, not the lander. Rosetta is capturing hundreds of amazingly detailed photos of the comet and analyzing the dust and gas given off by it as it vaporizes.
Why studying comets is so valuable
All this data is so valuable because the comet likely formed 4.6 billion years ago, from material leftover as Earth and the solar system's other planets were coalescing. As a result, understanding the composition of this comet — and comets in general — could help us better model the formation of the solar system.
Moreover, many scientists believe that in the period afterward, when the solar system was still a chaotic, collision-filled system, comets and asteroids were responsible for bringing water and perhaps even organic molecules to Earth. By analyzing data collected by Philae on ice and other substances on the comet's surface, we could gather important clues as to whether the hypothesis is correct.
In other words, data collected by a tiny robot on this lopsided, spinning comet, millions of miles away, could provide a window into the history of all life on earth. In the coming years, as scientists analyze this data and publish this research, we'll learn a whole lot more.
Thank you, @ESA_Rosetta! I did it! I became the first spacecraft to land on a comet & study it! But it’s not over yet… #CometLanding— Philae Lander (@Philae2014) November 15, 2014
Update: This post was edited to reflect the news that Philae was unsuccessful at extracting a rock sample.