Swanson, who retired from NASA in August and is working at Boise State University in Idaho, says the agency is already considering some of these isolation problems. He took part in a time delay experiment on station where the astronauts were expected to do simple tasks by themselves. And when astronauts are selected, it's not necessarily for what they know - it's how well they learn and work in teams.
"Do they play well with others, are they calm under pressure, do they have mechanical aptitude, are they well rounded, all these kind of things make a big picture," Swanson told Discovery News.
PHOTOS: Watching the Sunsets of Mars Through Robot Eyes
Before leaving for a long-duration mission outside Earth orbit, Swanson added, astronauts would be told which systems could be fixed on the fly and which would require a call back to ground (waiting for an answer.) The crew commander would be responsible for more daily administration to partially replace the instant communication people have with the ground.
As for unknown unknowns - the psychological or physical challenges of Mars that we don't know about yet - Swanson said NASA is always trying to think about what they may not know. There are open questions such as supplies for three years away, or how to keep astronaut spirits up without live conferences with family. "It's a huge effort," he said, adding that planning for that mission would take a while.
A NASA spokesperson said the physical requirements for astronauts would not change in Orion compared to shuttle or station, but did not respond to questions about how NASA expects astronaut selection generally would change (if at all).