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.

As we begin to have landings on the moon, we can alternate those with vertical launch of similar crew modules on similar launch vehicles for vertical-launch tourism in space, if you want to call it that adventure travel.

It's real easy to manufacture what you think the people want to hear. But that's not very honest.

Retain the vision for space exploration. If we turn our backs on the vision again, we're going to have to live in a secondary position in human space flight for the rest of the century.

Everyone should take their hats off to Neil Armstrong. He is a humble guy who doesn't wave his own flag.

It's been one of the greatest challenges that ever came along in my life; it was one of the more difficult things to do.

There's no guarantee that the United States will be around 200 years from now.