It was audacious, it was bold, but it was a success. For the first time, humanity has a physical presence on the icy surface of a passing comet – cosmic objects that have both fascinated and terrified human beings since the dawn of history.
The presence comes in the shape of a fridge-sized robotic probe named Philae which separated yesterday as planned and on cue from its mother ship, the Rosetta spacecraft launched more than 10 years ago.
A few minutes after 4pm British time, the European Space Agency (ESA) confirmed after an anxious wait of seven hours following its separation from Rosetta that Philae had landed on Comet 67P/ Churyumov-Gerasimenko, orbiting the Sun more than 510 million miles away in the direction of the constellation Sagittarius.
Travelling through space at a speed relative to the Sun of more than 41,000mph, the Philae lander is now riding piggy-back on a 4km-wide lump of rock, ice and dust that some have likened to a rubber duck due to its odd, double-lobed shape.
In pictures: European Space Agency's Rosetta mission
In pictures: European Space Agency's Rosetta mission
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Image of Comet 67P/CG taken by the Philae lander from a distance of approximately 3km from the surface
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Rosetta's lander Philae took this parting shot of its mothership shortly after separation
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Parting shot of the Philae lander after separation, captured by one of Rosetta's cameras
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A technician celebrates after the successful landing of the Philae lander, in the control room at the ESA headquarters in Darmstadt
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Scientists celebrate at a mission observation centre in Toulouse, southern France as they receive information that Philae has landed on the Churyumov-Gerasimenko comet
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Astronomer Klim Ivanovych Churyumov, who discovered the comet 67P/ Churyumov-Gerasimenko in 1969, reacts after the successful landing of the Philae lander on the comet
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A model demonstrates how the landing device Philae, of the space probe Rosetta, stands on the comet 67P/Churyumov-Gerasimenko at the press center of the satellite control center of the European Space Agency in Darmstadt, Germany
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An artist impression of Rosetta's lander Philae on the surface of comet
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Picture taken on October 28 by the navigation camera on Rosetta shows the boulder-strewn neck region of comet 67/P Churyumov-Gerasimenko. It was captured from a distance of 9.7 km from the center of the comet
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Picture taken on October 24 shows a raised plateau on the larger lobe of the comet
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The probe is supposed to fly to a comet and put down a small laboratory on the top of it
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A scientist from the European Space Agency with an airworthy copy of space probe 'Rosetta' in the control center in Darmstadt, Germany
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Maneuvers designed for the actual space probe are simulated with the replica. 'Rosetta' will be woken up from an energy saving hibernation after 957 days
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A European Space Agency employee sits in the control room for the Rosetta mission in Darmstadt, Germany
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Scientists at the European Space Agency are expecting their comet-chasing probe Rosetta to wake from almost three years of hibernation
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Europe's Rosetta probe on a NASA mission
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NASA is participating in the European Space Agency's Rosetta mission, whose goal is to observe one such space-bound icy dirt ball from up close for months on end
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An impression of the Philae lander
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ESA probe Rosetta with Mars in the background. The three-tonne probe blasted off aboard an an Ariane V rocket from Kourou, French Guiana in 2004
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Rosetta orbiter deploying the Philae lander to comet 67P/Churyumov–Gerasimenko, the spacecraft measures 32 m across including the solar arrays, while the comet nucleus is thought to be about 4 km wide
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The spacecraft, festooned with 25 instruments between its lander and orbiter (including three from NASA), is programmed to 'wake up' from hibernation
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An Ariane V carrying the three-tonne probe Rosetta blasting off from Kourou, beginning a decade-long quest to hunt a comet in the depths of the Solar System and shadow it around the Sun in a bid to tease out secrets of how life began on Earth
Nine minutes after 4pm, Rosetta’s flight manager Andrea Accomazzo announced to the world that the Philae probe had landed safely. “We see the lander sitting on the rock,” Dr Accomazzo said.
Jean Jacques Dordain, the director general of ESA, quickly followed up with a comment on just how momentous was the achievement: “We are the first to do this – and that [achievement] will stay forever.”
Even Captain Kirk, otherwise known as the Star Trek actor William Shatner, tweeted his congratulations when the Philae lander finally came to rest on the surface of the comet: “Cometlanding# Hooray!!!!”
David Parker, chief executive of the UK Space Agency, performed a very British reality check when he told the waiting audience gathered at the European Space Operations Centre in Darmstadt, Germany: “Hollywood is good, but Rosetta is better.”
ESA engineers said that the landing was softer than expected judging from the 4cm depression of Philae’s legs, but there was some concern over the failure of the probe’s anchors to fire into the surface, suggesting that the lander may not be fixed as tightly to the comet as ESA would have liked.
“Apparently the anchors didn’t deploy, so there’s a concern about the stability of the lander,” warned an ESA engineer.
Nevertheless, the mission’s main goal of landing a probe softly on the surface of a distant comet appeared to have been a resounding success.
“This is the most difficult landing in space history, like landing a balloon in a city centre on a windy day with your eyes closed,” said Matthew Genge, lecturer in earth and planetary sciences at Imperial College London.
The day of the landing started with high drama as Philae failed to switch on properly during the preparations for its separation from Rosetta. ESA engineers solved it by the old trick of turning it off and on again – and it worked.
The separation went as planned and both mother ship and lander managed to take parting shots of one another as they slowly drifted away. Philae finally landed just after 3.30pm British time but it took another half hour for the probe to confirm its presence on the comet’s surface.
Martin Barstow, professor of astrophysics and space science at the University of Leicester, said: “The Rosetta mission has been a tremendous adventure for ESA and the scientists involved. It has already proved to be a scientific success and promises to deliver much more over the next months and years. The riskiest part, landing the Philae spacecraft on the surface of the comet, has never been done before.”
The Philae lander will now travel with the comet as it continues its journey around the Sun. It should witness the plumes of vapourised gases emitted from the icy surface as the comet feels the rising heat of its orbital summer.
At the same time, it will drill into the comet’s surface to analyse samples of ancient dust and rock left after the creation of the Solar System.
Meanwhile, the Rosetta space craft will continue to orbit around the comet, taking measurements from on high, as the trio continue to orbit the Sun. One question Rosetta hopes to answer is whether comets contain the organic building blocks of life, Dr Genge said.
“Did comets deliver the building blocks of living things and start life on Earth? We may soon know with the help of Rosetta,” he said.Reuse content