Since 29 August 2015, the group lived in close quarters in a dome, without fresh air, fresh food or privacy.
Experts estimate that a human mission to the Red Planet could take between one and three years.
The Nasa-funded study run by the University of Hawaii is the longest of its kind since a Russian mission that lasted 520 days.
Having survived their year in isolation, the crew members said they were confident a mission to Mars could succeed.
MalasadasWaikiki Malasada BoothFebruary 2nd, 201871 days to go.