The European Space Agency's Philae probe has made history by landing on Comet 67P/Churyumov-Gerasimenko.
Stephan Ulamec, project manager for Philae, announced: "We are there and Philae is talking to us. First thing he told us was that the harpoons have been fired, rewound and the landing gear has been moved inside so we are sitting on the surface."
Jean Jacques Dordain, the director general of ESA, said: "We are the first to do this, and that will stay forever."
The Philae probe successfully separated from the Rosetta orbiter this morning.
The lander parted from the orbiter at a distance of 317 million miles away from Earth. Confirmation was received at ESA's Space Operation Center, ESCO, in Darmstadt, Germany. The radio signals took 28 minutes and 20 seconds to reach Earth, so while the confirmation came through at 9.03am GMT, it was sent at 8.35 am GMT.
Philae then began to head towards Comet 67P/Churyumov-Gerasimenko. The probe cannot directly send signals to Earth, so sends them to Rosetta, which in turn passes them on to the scientists in Germany. Controllers have been in contact with the lander all day.
The probe touched down at about 4pm GMT today, and the first image from the surface is expected around two hours later. The entire operation is being livestreamed from the Space Operation Center.
Dr Detlef Koschny, who has worked on the Rosetta mission on and off since 1990, told VICE News that the mood at the ESA before the landing was one of "professional anxiousness."
"The people are calm but of course everybody is full of tension because we want this to succeed." He added: "If this works out it's like the cherry on the cake for this mission."
Rosetta is a robotic space probe, built and launched by the European Space Agency in 2004. In August it became the first spacecraft to successfully orbit a comet. Its mission is expected to last until December 2015, during which time a variety of tests will be performed on the comet.
The probe is equipped with a drill that will take samples from underneath the comet's surface. These will then be transported to the lander, which will test them on a series of devices: a gas chromatograph mass spectrometer, to analyze the ratio of different forms of elements; an alpha proton x-ray spectrometer which will examine chemical composition using x-rays and alpha particles; and a magnetometer and plasma monitor to study the comet's magnetic field.
Koschny said that even if something went wrong with the landing, 80 percent of the science had already been gathered, but the lander would "give us a ground reference point that will help us interpret the data."
Rosetta was rewoken in January this year, after most of its power systems were shut off in 2011 to save energy. Koschny said that when they begun observation again, the comet was barely a speck, "but in July we really started getting excited because the comet was large enough that you could see more than a few dots in the images."
Koschny added that they have already learned more from this mission than from any previous ones, because all the others involved flying by a comet, rather than tracking it. "This time we have a chance to observe the changes."
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