I don't think we're going to build a 50-person spacecraft or a 100-person spacecraft.

I failed music when I was a teenager.

If you want to say that the sky is black, and if I'm there, even if I fall back down again, I will be weightless for a period of time - maybe that's the definition of space.

Don't waste your time on beaming people up or down. Instead, consider gravity waves as advanced physics of the universe that could be used to travel interstellar distances.

Mars, we know, was once wet and warm. Was it home to life? And what can living and learning to work on its rust-colored surface teach us about the future of our own planet, Earth? Answering those mysteries may hold the key to our future.

My first biography written in '73 was not 'Journey To The Moon.' It was 'Return To Earth.' Because for me, that was the more difficult task - disappointment.

I think both the space shuttle program and the International Space Station program have not really lived up to their expectations.