As always, space remains an unforgiving frontier, and the skies overhead will surely present obstacles and setbacks that must be overcome. But hard challenges demand fresh approaches, and I'm optimistic that Stratolaunch will yield transformative benefits - not only for scientists and space entrepreneurs, but for all of us.

Overhead will eat you alive if not constantly viewed as a parasite to be exterminated. Never mind the bleating of those you employ. Hold out until mutiny is imminent before employing even a single additional member of staff. More startups are wrecked by overstaffing than by any other cause, bar failure to monitor cash flow.

If you like overheads, you'll love PowerPoint.

For me, the making of a documentary to mark the 70th anniversary of the Battle of Britain was an intensely personal journey. I was born in February 1940, so I was just six months old as the battle raged overhead.

Nothing is safe from you. If I were to court a girl who lived on an iceberg in the middle of the ocean, sooner or later- probably sooner- I'd look up to see you swooping overhead on a broomstick. In fact, by now I'd be disappointed in you if I didn't see you.

I heard an airplane passing overhead. I wished I was on it.

Do you know what the overhead is of the Medicare system? One-point-zero-five percent. Do you know what - private insurance is 30 percent in overhead and profits? Given a choice how I'm going to improve health care I'm going to take it away from private insurance profits and overhead. Wouldn't you?

If you like overheads you'll love PowerPoint.

Here's the thing that I think about life - if you manage to get into a space where you don't need that much where the overhead of your life is not that great and you're pretty happy and relaxed without that much stuff you are really liberated because you never have to say yes to something because you want another refrigerator or car!