Get the shuttle out of the garage. It's in its prime of its life. How could we just put it away?

Some astronauts describe the routine flushing of urine into space, where the freezing temperatures turn the droplets into a cloud of bright, drifting crystals, as being among the most amazing sights they saw on an entire voyage.

The moon is bland in color. I call it shades of gray. You know, the only color we see is what we bring or the Earth, which is looking down upon us all the time. And to find orange soil on the moon was a surprise.

Nobody can take those footsteps I made on the surface of the moon away from me.

Prepare for the unknown, unexpected and inconceivable . . . after 50 years of flying I'm still learning every time I fly.

I've been asked about UFOs and I've said publicly I thought they were somebody else, some other civilization.

Curiosity is the essence of human existence. 'Who are we? Where are we? Where do we come from? Where are we going?' I don't know. I don't have any answers to those questions. I don't know what's over there around the corner. But I want to find out.