The main thing to know about an astronaut, if you want to understand his psychology, is not that he’s going into space but that he is a flyer and has been in that game for 15 or 20 years. It’s like a huge and very complex pyramid, miles high, and the idea is to prove at every foot of the way up that pyramid that you are one of the elected and anointed ones that have the right stuff.
The right stuff is not bravery in the simple sense; it is bravery in the most sophisticated sense. Any fool can put his hide on the line and throw his life away in the process. The idea is to be able to put your hide on the line — and then to have the moxie, the reflexes, the talent, the experience, to pull it back in at the last yawning moment — and then to be able to go out again the next day and do it all over again — and, in its best expression, to be able to do it in some cause, in some calling that means something.
Walter Cunningham
Apollo 7 astronaut and Marine Corps fighter pilot, writting in his 1977 book All American Boys, An Insider’s Look at the U.S. Space Program.