[freshair]

> These are the people that have been selected to be astronauts. How often have you seen one have a breakdown during a mission?

I'm not sure about mental breakdowns per se, but there has been some insubordination. I can't recall which at the moment, but one of the Gemini astronauts during an EVA refused to get back into the capsule until he was plead with. Perhaps this could be categorized as a mental breakdown. (Edit: It was Ed White: https://en.wikipedia.org/wiki/Gemini_4#Extra-vehicular_activ... )

There was also that well publicized incident in 2007 where an astronaut's life unraveled and their career was destroyed, but that wasn't during a mission.