7.33pm GMT

There was a moment of silence, then the place erupted with a deafening cheer. Almost two hundred journalists, scientists and engineers were throwing their arms in the air, bear-hugging their nearest neighbours whether they knew them or not.

ESA’s billion-Euro comet chaser Rosetta has woken up after 31 months in hibernation, and spoken to Earth. The signal appeared on a computer screen as a tremulous green spike but it meant the world – maybe even the solar system.

“Now it’s up to us to do the work we’ve promised to do,” said an emotional Matt Taylor, ESA’s project scientist for the mission, to the assembled crowd.

Just 10 minutes before he’d been facing an uncertain future career. If the spacecraft had not woken up, there would be no science to do and the role of project scientist would be redundant. If the signal had come in on time in would have been great. The fact that it came in half an hour late, only made it sweeter in the end.

Although you would not have known at the time. Taylor hid his nerves well, even joking about the wait on Twitter but when the clock passed 19:00CET, making the signal at least 15 minutes late. Then things began to change. People started rocking on their heels, clutching their arms around themselves, and the banter that had helped pass the time so far dried up. Taylor himself sat down, and seemed to withdraw. Then suddenly, everything was good again.

“I told you it would work,” he says to me with a grin to acknowledge his previous nerves.