My writing is a combination of three elements. The first is travel: not travel like a tourist, but travel as exploration. The second is reading literature on the subject. The third is reflection.

Exploration is really the essence of the human spirit.

We shall not cease from exploration, and the end of all our exploring will be to arrive where we started and know the place for the first time.

I suppose a good director is like a teacher. I think that someone like David Cronenberg was very much like a teacher, because there's an openness, but a certain set of rules of behavior, and a certain conduct expected. But there's an atmosphere that's relaxed and conducive to exploration, and that is created by someone like Cronenberg.

In my opinion, future space exploration will require us to inhabit the moon, initially, and later Mars. This is a humongous task for any one nation to carry out.

Revealing water in significant quantities on the Moon could truly be a turning point in space exploration.

Fifty years after humans landed on the moon for the first time, America has driven a golden spike on the trail to new space exploration feats through the work of our commercial partner SpaceX and all of the dedicated and talented flight controllers at NASA and our international partners.

I think even in bad times it's good to keep some money going into research. And that's the purpose of the whole space program. It's not just exploration and going to see how far we can go out into space and keep people alive and bring them back, although exploration certainly has its place.

We collectively have a special place in our heart for the manned space flight program - Apollo nostalgia is one element, but that is only part of it. American culture worships explorers - look at the fame of Lewis and Clark, for example. The American people want to think of themselves as supporting exploration.

I think a lot of the American people feel more than a little disappointed that the high-water mark for human exploration was 1969. The dream of human space travel has almost died for a lot of people.

All space exploration is risky. As an astronaut, I had to decide each and every time I went to space whether or not to risk my life for the mission.

I've always been interested in the idea of space exploration. When I was younger it was just a dream, but the theory of rockets being able to travel through space was very much alive. I found it very exciting.

Looking down the road, space exploration and the benefits it yields - in medicine and information technology - should not be overlooked.

Astronauts have been stuck in low-Earth orbit, boldly going nowhere. American attempts to kick-start a new phase of lunar exploration have stalled amid the realisation that NASA's budget is too small for the job.

I stayed in the astronaut program until 1993. People ask me why I left. I thought I had a lot of things to contribute that would be difficult to do if I stayed. I thought I could have a stronger voice as an advocate for space exploration. So I ended up starting my own technology consulting company.

I think space exploration is very important. I think there is very intelligent life on Mars. I believe that Martians are spying on us from the bottom of the ocean.

Space exploration promised us alien life, lucrative planetary mining, and fabulous lunar colonies. News flash, ladies and gents: Space is nearly empty. It's a sterile vacuum, filled mostly with the junk we put up there.

The moon and other celestial bodies should be free for exploration and use by all countries. No country should be permitted to advance a claim of sovereignty.

I think we are at the dawn of a new era in commercial space exploration.

Millions of people were inspired by the Apollo Program. I was five years old when I watched Apollo 11 unfold on television, and without any doubt it was a big contributor to my passions for science, engineering, and exploration.

The Connecticut Center for Science and Exploration will be a building that will connect the excitement of science to the surrounding streets, river and highway. These forms are ambitious and dynamic. They appear to reach out beyond their physical limits.

NASA projects often have romantic names that link into a long history of exploration and adventure: Atlantis and Discovery, for example.

NASA is an engine of innovation and inspiration as well as the world's premier space exploration agency, and we are well served by politicians working to keep it that way, instead of turning it into a mere jobs program, or worse, cutting its budget.

America is the spirit of human exploration distilled.