“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.”— Alan Shepard, en.wikiquote.org
“It is a very sobering feeling to be up in space and realize that one's safety factor was determined by the lowest bidder on a government contract.”— Alan Shepard, goodreads.com