When you're getting ready to launch into space, you're sitting on a big explosion waiting to happen.

After the Challenger accident, NASA put in a lot of time to improve the safety of the space shuttle to fix the things that had gone wrong.

There's a huge amount of pressure on every astronaut, because when you get right down to it, the experiments that are conducted on a space flight, or the satellites that are carried up, the work that's to be done, is important and expensive work, and you are up there for a week or two on a Space Shuttle flight. The country has invested a lot of money in you and your training, and the Space Shuttle and everything that's in it, and you have to do things correctly. You can't make a mistake during that week or two that you're in space.

I've discovered that half the people would love to go into space and there's no need to explain it to them. The other half can't understand and I couldn't explain it to them. If someone doesn't know why, I can't explain it.

It's easy to sleep floating around - it's very comfortable. But you have to be careful that you don't float into somebody or something!

If they asked me if I wanted to go into space tomorrow, I'd do it in a heartbeat. On the other hand, if they asked me if I wanted to go into training for three years and then go into space again, I'd probably say no.

But when I wasn't working, I was usually at a window looking down at Earth.