Sometimes people wonder why aeroplanes are so cheap and rockets are so expensive. Even the most superficial comparison shows one obvious difference: aeroplane engines use outside air to burn their fuel, while rockets have to carry their own oxidisers along.

I am afraid of aeroplanes. I've been able to avoid flying for some time, but I suppose, if I had to, I would. Perhaps it's a case of a little knowledge being a dangerous thing. At one time, I had a pilot's licence and 160 hours of solo time on single-engine light aircraft. Unfortunately, all that seemed to do was make me mistrust large aeroplanes.

I was a loner as a child and happiest at home launching toy rockets and aeroplanes. When I started causing trouble in my third year at grammar school Mum was really surprised. My parents sent me to a child psychologist who suggested I might have Asperger's syndrome.