Mars has been flown by, orbited, smacked into, radar examined, and rocketed onto, as well as bounced upon, rolled over, shoveled, drilled into, baked and even blasted. Still to come: Mars being stepped on.

When you're in a spacecraft, you need to know what things you can touch and what things you shouldn't touch!

Exploration is wired into our brains. If we can see the horizon, we want to know what's beyond.

You can tell I'm not too bashful about some of my feelings.

I understand that Detroit was a pretty rough place to grow up in the '70s and '80s.

I think humans will reach Mars, and I would like to see it happen in my lifetime.

What are you going to do with astronauts who first reach the surface of Mars and then turn around and rocket back home-ward? What are they going to do, write their memoirs? Would they go again? Having them repeat the voyage, in my view, is dim-witted. Why don't they stay there on Mars?