NASA needs to focus on the things that are really important and that we do not know how to do. The agency is a pioneering force, and that is where its competitive advantage lies.

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

A hybrid human-robot mission to investigate an asteroid affords a realistic opportunity to demonstrate new technological capabilities for future deep-space travel and to test spacecraft for long-duration spaceflight.

The society of life on Mars, or the challenge of making Mars more livable, will have significant benefits on our attempts to modify and change in some ways the environment here on Earth.

The g-forces increased and I wasn't able to continue to hold the camera against the window, so I had to lay it back against my chest, but still continued to photograph the re-entry until there was no more unusual visual effects of the energy in the atmosphere. And it was very comforting to understand that the people in Houston, the controllers, had very high confidence that we were on the right path.

You are not going to change the minds of people who are looking for attention.

I want to reach a new generation. That's why I am Twittering now. I have a BlackBerry, an iPhone and a Mac.