Chemical propulsion is obsolete to go anywhere other than the moon.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.

We leave as we came, and, God willing, as we shall return, with peace and hope for all mankind.

Perhaps the two greatest moments of my life were standing on the moon and being outside of the room when my granddaughter was born! We tend not to remember the worst.

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

Curiosity is the essence of human existence.

We went into darkness after being in daylight the whole time on the way to the Moon. And then we went into darkness. And we're in the shadow... of the Moon.