The European Space Agency has successfully landed a spacecraft on a comet for the first time.
ESA's Philae probe has landed on the speeding comet 67P/ Churyumov-Gerasimenko and is sending communications back to Earth.
The £1bn Rosetta mission, named after the Rosetta stone, hopes to study the comet's chemical composition and surface materials to give fresh insights into how the Solar System formed more than 4.5 billion years ago.
Since taking off in March 2004, the Philae lander has travelled more than 6.4 billion kms to catch up with the comet, which was travelling at 30,000 m/ph.
ESA director general Jean-Jacques Dordain said: "It's a big step for human civilisation."
He added: "Esa and its Rosetta mission partners achieved something extraordinary today.
"Our ambitious Rosetta mission has secured another place in the history books: not only is it the first to rendezvous with and orbit a comet, but it is now also the first to deliver a probe to a comet's surface."
Philae touched down on schedule after a nerve-wracking seven-hour descent from spacecraft Rosetta around 300 million miles from Earth.
Stephan Ulamec, the mission's lander chief, confirmed that Philae had landed on the comet. He said: "Philae is talking to us. The harpoons have fired and the landing gear is inside. Philae is sitting on the surface and is talking to us. We are on the comet."
The announcement was met with jubilant scenes at the control room in Darmstadt, Germany.
"We can't be happier than we are now," added ESA flight director Andrea Accomazzo. "We have definitely confirmed that the lander is on the surface."
Space Foundation's Elliot Pulham described the successful landing as a "tremendous accomplishment".
He added: "We congratulate our partners at German Space Agency (DLR) and ESA for achieving yet another milestone during this ambitious mission."
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