‘But a few weeks ago something happened.’ My throat feels tight. I look right at Mum and she holds my gaze; I need her to know that I’m saying this to her. ‘I had my very own big bang – and it changed everything. For the first time in my life, I felt lost in the universe … I was scared and I couldn’t cope on my own. Then I discovered my Earth crew.’

I look back across the hall. ‘To put one astronaut in space requires years of training from thousands of highly educated, unbelievably skilled people. I had a bunch of teenagers – Rose, Jackson and Annie – and they lifted me up and got me here today.’

From somewhere at the back of the room a loud ‘Whoop!’ rings out.

‘That’s Annie,’ I say. ‘No matter where I am, Annie is ready to help me work the problem. She’s calm and collected and has the sort of brain that can cope with any mission contingency; she would definitely have got Apollo 13 back to Earth.’

‘And I’ve got Ed – we sit next to each other in science. For a long time, I thought Ed was someone I had to compete against. But I got that so wrong. Everyone knows that Buzz Aldrin and Neil Armstrong were the first people to walk on the moon, but they could never have got there if Michael Collins hadn’t been waiting for them in orbit. Ed is my Michael Collins. He put my mission first, which is why there’s an empty seat on the stage behind me.’

‘Before I met my Earth crew, I thought I could get to space just by studying – mathematics, physics, computing … I’ve even started to learn Russian –’

Laughter bursts out from the audience.

‘No, really,’ I say, then to prove it, I add, ‘Ya mogu govorit’ po-russki! I forgot that an astronaut needs more than knowledge. They also need to reassure others and put others first. And they need to trust their team.

‘Sir Isaac Newton said, “If I have seen further, it is by standing on the shoulders of giants.” Yuri Gagarin, the first human to reach space, got there because throughout history, human beings, from Aristotle to Einstein, used their brains in crazy, incredible ways. Neil Armstrong could only take one giant leap for mankind because a crew of thousands stood behind him. I’ve realised that space isn’t an escape from the chaos of human beings, it’s something I have because of the chaos of human beings.’

I think back to that afternoon when Elsa was ill and suddenly see so clearly what Grandad was trying to say. ‘Nietzsche said that we need chaos inside ourselves,’ I press a hand against my chest, ‘if we are to give birth to a dancing star.’ My eyes find Mum’s again. ‘And I have two particularly chaotic human beings to thank for filling my mind with curiosity and encouraging me to look up in the first place. My grandad gave me my first pair of binoculars and taught me how to use them. He made me a rocket that took me to the moon on a daily basis. My mum painted the Milky Way on my bedroom ceiling. She put an arrow on it pointing to Earth and wrote next to it, You Are Here. Mum said that Earth was just my starting point. She has always believed I could go anywhere.’