Five simple words marked the fulfilment of an extraordinary feat of space exploration yesterday when scientists announced: ‘We are on the comet.’
To cheers and hugs, ecstatic experts delivered the news that a machine the size of a dishwasher had dropped onto an icy rock more than 300 million miles away.
However, they later revealed that the mission is already in jeopardy as it emerged the lander, which was supposed to use harpoons to tether itself to the comet’s surface, had been unable to fire them and appeared to be moving around.
It was a worrying end to an extraordinary day.
At the European Space Agency’s mission control, a faint radio signal came back from the Philae lander at 4pm – proof that it had finally reached the surface of the comet 67P/Churyumov-Gerasimenko after a decade-long chase through space.
Dr Stephan Ulamec, who ran the audacious landing programme, said early tests suggested the craft had bounced softly before turning and settling again.
He said: ‘It touched down and was re-bouncing. So maybe today, we didn’t just land, we landed twice.’
Last night the team were still not sure how securely Philae was fastened after landing thrusters and anchoring harpoons failed to fire.
It was not clear if its three ice screws had deployed either.
Dr Ulamec said: ‘Did we just land in a soft-sand box and everything is fine? Or is there something else happening? We still do not fully understand what has happened.’
Scientists will not know the status of the project until further tests are completed this afternoon.
However, last night they were treating the landing itself as a success.
British scientist Dr Matt Taylor, who played a key role in the mission, said: ‘To see this mountaineering effort, that we’ve descended a lander to the surface of a comet, I can’t put words to it. It’s beautiful.’
And the expert was so confident of success that he had even had an image of the space probe tattooed on his right leg.
Before the attempt yesterday, there was also a good luck message from a man who had once boasted of boldly going into space himself.
Star Trek actor William Shatner sent the team a video in which the 83-year-old said: ‘Good luck Rosetta, Philae’s gonna land.’
One scientist then described the seven hours of ‘terror’ they went through to drop the Philae lander 13.6 miles above the comet from its mothership, Rosetta.
Dr Matthew Genge, of Imperial College London, said during the wait: ‘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.’