Chemical propulsion is obsolete to go anywhere other than the moon. Three days - that's acceptable. But for Mars, we need propulsion technologies to get us there in, say, 60 days - then spend whatever length of time we want to spend and return when we want to come home.

I think America has a responsibility to maintain its leadership in technology and its moral leadership in the world, to explore, to seek knowledge.

If you begin to think you're something you're not, you're looking in the wrong mirror.

I do believe there is life in outer space. Mathematically, there has to be, and if you believe as I do that there is a creator of the universe, then how can we be so arrogant to believe he created life here and nowhere else?

Today, we are on a path of decay. We are seeing the book close on five decades of accomplishment as the leader in human space exploration.

Another hundred years may pass before we understand the true significance of Apollo. Lunar exploration was not the equivalent of an American pyramid, some idle monument to technology, but more of a Rosetta stone, a key to unlocking dreams as yet undreamed.

Yes, I am the last man to have walked on the moon, and that's a very dubious and disappointing honor. It's been far too long.