A lot of my role is advocacy, and as a scientist, you're an advocate, too, because you are coming up with a theory and having to convince your fellow scientists that you're right.

One of the big things about space exploration is that it is as expensive as it is complicated, and you need all the countries of the world to help if you want to accomplish big goals.

With the mission to Mars, the whole world wants to get involved. So we actually have 13 different space agencies from around the world working on the global exploration road map.

My key aim is to get man on the surface of Mars by the mid-2030s.

Philosophy was once considered science.

Like tens of thousands of others, I have been a spectator of, rather than a participator in, the activities - political, commercial, sociological, scientific - of the times in which I have lived.

Every scientific truth goes through three states: first, people say it conflicts with the Bible; next, they say it has been discovered before; lastly, they say they always believed it.

I never watch MTV. I don't have time to watch TV. And when I do, I'm watching the Discovery Channel. 'Deadliest Catch: Crab Fishing in Alaska,' that's my show.