When I was eight we spent our summer holiday in London, and my mum took my brother and me to Earl’s Court, to see the Russian Exhibition. It was really crowded, and suddenly, there was an extra commotion. People were pushing through with thick red ropes. “Hold on to the rope!” said Mum, worried about losing us in the crush. Then, walking straight towards us, waving and smiling to the crowd, came Yuri Gagarin. Yuri Gagarin – who three months earlier had been the first man in space.

And I knew: that was what I wanted to do.

Not long after that, I came across an author called Hugh Walters. He wrote a series of books with wonderful titles: Journey to Jupiter, Mission to Mercury, Destination Mars. The spaceship captain in all these stories was a physicist. So it was simple: to go to space, I needed to become a physicist.

It’s twenty years later. It’s eleven o’clock on a Saturday night in October, and I’m standing in the desert in New Mexico. The experiment I’ve spent the last four years developing and testing is now sitting on top of an Astrobee rocket at White Sands Missile Range, ready to be launched into space.

The tannoy comes to life: “T minus one minute and counting”. There’s a public highway running for about 70 miles across the range, and the military police have closed it. We have a one hour launch window.

“T minus 20 seconds and holding.”

The countdown has stopped: something’s wrong, and I run back into the control bunker, my pulse racing. It’s the wind. Range control have to be certain that the launch and re-entry trajectories will stay within the range boundaries, and right now the wind is too strong.

“T minus 20 seconds and counting.”

It’s back on. I’m clenching my teeth so hard to stop them chattering that my jaw aches. “10… 9… 8…” My mouth is as dry as the desert, and I can’t control the trembling. “3… 2… 1…” Oh, please work!

Then there’s the sudden roar, as the rocket bursts into life. And it’s gone. Hurtling safely through the atmosphere into space, as planned. With a take-off so fast, I didn’t even see it go!