After traveling through space for 10 years, the European Space Agency's Rosetta orbiter released the Philae lander that touched down Wednesday, Nov. 12 on comet 67P/Churyumov-Gerasimenko, which is about only 3 miles wide at its widest point.
When Philae was dropped onto the surface of the mountain-sized comet 67P/Churyumov-Gerasimenko, two harpoons designed to tether it to the surface failed to fire, and scientists say the lander made two bounces before settling into a hole where it was surrounded by rock-like structures that block the sun. With its internal battery not receiving optimal sunlight, the lander's power went out 56 hours after landing. The lander had enough time to run all the experiments on board and return information back to Earth.
Early image from Philae
Scientists initially thought Philae would land on a powdery surface but now suspect the comet's surface is more rocky as the lander bounced before coming to rest.
Mission timeline: 2004 to 2015
During its 10-year flight, the Rosetta orbiter looped around the inner solar system several times before crossing the asteroid belt and rendezvousing with comet 67P in May 2014, when it was 418 million miles away from the sun. Since then the orbiter has escorted the comet as it flies towards the sun. Comet 67P will make its closest approach to the sun in August 2015; then the spacecraft and comet will leave the inner solar system together.
Comet 67P belongs to a group of comets whose orbits are controlled by Jupiter's gravity. These comets are thought to have originated from the Kuiper Belt, a collection of icy bodies located beyond Neptune.
The Rosetta orbiter
The aluminum Rosetta orbiter is powered by solar panels that extend from its sides. The orbiter has 24 thrusters to control its trajectory and altitude.
After mapping the surface of comet 67P, scientists picked from five potential landing sites. In September 2014 they chose site J, now known as Agilkia, to minimize risk to the lander.
Once the 220-pound Philae lander was released from Rosetta, scientists had no control over its steering. The operation required flawless communication between the two spacecraft, only one of which could send signals to Earth.
On the surface
The Philae lander has sent images of comet 67P along with the first panorama from the point of final touchdown. Superimposed on top of the image is a sketch of the lander in what scientists believe is its current position.