We have the ability, at such high fidelity, to simulate the physical world through computers. But when the spiritual world or human behavior comes into play, we don't have a very good model for that at all.

I was the first Navy, Marine or Air Force person who had been an astronaut to return back to the Air Force. I had certain expectations about what would be a reasonable and desirable position to be assigned to after my years of service.

Any observations from the Moon or a sense of realising this or that about the greater meaning of things wasn't as influential for me as the experience of coming back and dealing with being a person who's been to the Moon.

I think the public needs to be reminded just how much inspiration and intention was given throughout the world to be bold, to send human beings to the moon in the '60s and the '70s. It's important now to bring together the nations that weren't able to do it then and help them do it. We need to move forward.

Being first outside the spacecraft would bring much more responsibility, and I really wasn't looking for that.

We should go boldly where man has not gone before. Fly by the comets, visit asteroids, visit the moon of Mars. There's a monolith there. A very unusual structure on this potato shaped object that goes around Mars once in seven hours. When people find out about that they're going to say 'Who put that there? Who put that there?' The universe put it there. If you choose, God put it there.

As we reflect back upon the tragic loss of Challenger and her brave crew of heroes who were aboard that fateful day, I am reminded that they truly represented the best of us, as they climbed aloft on a plume of propellant gasses, reaching for the stars, to inspire us who were Earthbound.