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.

I grew up in this business... A lot of my life has been centered around this question about how NASA is helping us to understand our own home planet... and to understand our place in the universe.