Look at what Silicon Valley has done - the advance of computers.

One of the major problems with long-term deep space human flight is the requirement for radiation shielding.

People communicate in Twittering ways. I've learned how to do that.

My favourite thing to do on this planet is to scuba dive.

I didn't start skiing until I was 50. My wife Lois taught me how to ski. I'm proficiently conservative.

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.

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