Astronauts need to be smart, calm, determined problem-solvers. (It helps if they look like Matt Damon.)

But when you’re picking people for a space mission, the group dynamics are just as important as people’s individual characteristics. That will be particularly true when NASA sends its first manned trip to Mars, since the mission has the potential to last several years.

Johns Hopkins recently won a grant to help pick the perfect slate of astronauts. The study will be carried out by Michael Rosen, whose background as a human factors psychologist who helps train and coordinate teams, particularly through creating simulated events.

He plans to begin his research with a look at medical residents working in Hopkins’s critical care units. These residents are both very smart and very over-worked; they’re also subject to stressful situations requiring snap-second decisions, which make them a good stand-in for astronauts, Rosen told the Sun. His research will involve seeing how study subjects respond to stress, but also how their individual response affects the team dynamics. Is someone’s voice too loud? Do they chatter too much? Such minor quirks might make you go legitimately insane if you were trapped in a small tube with someone for three years.

One thing to keep in mind: The Mars mission, if it even happens, won’t likely take place until after 2030. So any potential astronauts are just teenagers now.