We need a continuing presence in space. - Alan Shepard

We had some adverse conditions in the '60s, in the '70s and the '80s. The agency has risen above that in the past and will rise above that again.

I realized up there that our planet is not infinite. It's fragile. That may not be obvious to a lot of folks, and it's tough that people are fighting each other here on Earth instead of trying to get together and live on this planet. We look pretty vulnerable in the darkness of space.

If we had said 30 years ago that we were going to have only two incidents with casualties, we would have thought, 'Boy, that's great. To me, that indicates that the program has really exceeded what the early expectations were.