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.