"The only way to do great work is to love what you do."

"Don’t tell me that man doesn’t belong out there. Man belongs wherever he wants to go."

"Science does not have a moral dimension. It is like a knife. If you give it to a surgeon or a murderer, each will use it differently."

"We are still in the infancy of space exploration."

"If I have to choose between a rocket and a woman, I'll take the rocket."