I know depression usually has a grave cause and astronauts have quite an active schedule. But say their family dies. Depression makes you think and perceive time differently. Surely wouldn’t it become a risk to the mission? You can’t steamroll over it…
There’s an escape hatch. If they get too out of control, the other astronauts launch them out the door. On the side facing earth, so they don’t become space debris. They burn up in the atmosphere, and pose no risk anymore.