If you think of the Apollo capsule coming into Earth with a parachute, the Mars atmosphere is just so thin, you've got to find some way of slowing yourself down really rapidly.
When you look at Venus and the Earth, they formed at about the same place in the solar system. They're made of about the same materials; they're about the same size.
I live an hour from NASA's HQ in Washington, D.C., and sitting in a jam stresses me out.
You see countries like India really investing in their space program because they see it as inspirational and good for their economy.
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.
Every time I give a talk, I ask the audience - especially if it's kids - how many want to go to Mars. At least half raise their hands. I don't think there's going to be any shortage of volunteers.
