In particular, Russian cosmonauts have stayed aboard the Mir space station for stints up to eighteen months in duration, much longer than the six-month legs of a Mars mission. He just laughed when you casually mentioned it to him, but it's getting so that you can even hear him in your dreams. You feel like the spaceship's getting smaller and his whistling is getting louder. It wouldn't take much to bundle him into the airlock and hit the release. Everyone will believe you when you say it was an accident.
Astronauts usually get along.
If the Mars Direct mission architecture is employed, the astronauts will spend a total of 12 months in space and a year and a half on the Martian surface. And, more importantly, the Mars crew will have the knowledge that they are making history - motivation indeed. As they get further away from Earth, real-time conversations with friends and family will become impractical, but video messages and letters will still be possible. Anyone who thinks that a long-duration Mars mission will drive astronauts insane is underestimating the strength of human will. In fact, a bigger danger facing astronauts might not be the boredom and confinement of a Mars mission, but the adulation and constant attention they'll receive upon returning home.