I'm not an expert but here's my humble opinion. Being an astronaught has very stringent physical and mental requirements. It's probably easier(or cheaper) to pi

I'm not an expert but here's my humble opinion. Being an astronaught has very stringent physical and mental requirements. It's probably easier(or cheaper) to pick the smartest candidates from a group of very fit ones. To make a very crude analogy, it's easier to turn the star QB into a valedictorian than to turn the valedictorian into a QB. Ps. I love the verb grok. Such a great book.