The mission to land a space probe on the surface of a comet didn’t happen overnight.

It took 20 years of planning, of meticulous attention to detail, a long, long journey that ended with robot spacecraft the size of a large dog flying 34,000 mph (54,400km/h) from the Rosetta space probe to rendezvous with a comet over 300 million miles (480 million kilometres) away from Earth.

For Stephan Ulamec, the manager of the Philae lander programme, years of painstaking work was coming to an end at breakneck speed, and in front of the world’s cameras.

“You realise now, it’s not a simulation anymore,” says Ulamec. “You’re working for 20 years, and there is a risk that everything fails within minutes at touchdown.”

And something did go wrong. Philae didn’t land – at least not straight away. The initial impact with Comet 67P sent the robot explorer rebounding a kilometre into space before descending once again onto the comet’s surface two hours later, and hundreds of metres away from its intended spot.

So what goes through your mind when you don’t know whether your 20-year mission has been successful, and all eyes are on you? Watch the video to see how that tense wait unfolded at the European Space Agency’s control room.

See more from our series The Genius Behind: the most amazing technological and scientific breakthroughs of modern times, and the innovative minds behind them.

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