Comet space probe makes history
A spacecraft has landed on a comet for the first time in history, the European Space Agency announced.
The agency says it has received a signal from the 100-kilo (220 lbs) Philae lander after it touched down on the icy surface of the comet named 67P/Churyumov-Gerasimenko.
Flight director Andrea Accomazzo said from the DLR German Aerospace Centre in Darmstadt Germany: "We definitely confirm that the lander is on the surface."
Further checks are needed to ascertain the state of the lander.
The landing on the speeding comet marks the highlight of the decade-long Rosetta mission to study comets and learn more about the origins of these celestial bodies.
Scientists hope it will eventually provide answers to some of the biggest questions about the origin of the universe.
The landing caps a 6.4 billion-kilometre (four billion-mile) journey to study the four-km-wide (2.5-mile-wide) comet.
Philae was supposed to drift down to the comet and latch on using harpoons and ice screws. ESA announced hours before the release that a third component - an active descent system that uses thrust to prevent the craft from bouncing off the surface of the low-gravity comet - could not be activated.
During the descent, scientists were powerless to do anything but watch, because the vast distance to Earth - 500 million kms (311 million miles) - makes it impossible to send instructions in real time. It takes more than 28 minutes for a command to reach Rosetta.
Rosetta, which was launched in 2004, had to slingshot three times around Earth and once around Mars before it could work up enough speed to chase down the comet, which it reached in August. Rosetta and the comet have been travelling in tandem since then.
Rosetta and Philae plan to accompany the comet as it hurtles toward the sun and becomes increasingly active in the rising temperatures. Using 21 different instruments, the twin spacecraft will collect data that scientists hope will help explain the origins of comets and other celestial bodies.