The extent of the psychological stress on astronauts who embark on a multi-year journey to the Red Planet has hardly been researched. A documentary well worth seeing explains which problems have to be solved.
The author Stanislaw Lem already foresaw the problem in the science fiction classic “Solaris”: A psychologist is sent to the space station from which the planet Solaris is to be explored, partly because the crew there suddenly has all sorts of things appear. “Solaris” appeared in 1961, when space travel had only just begun and something like the psychology of the astronauts played a subordinate role.