Astronauts
Every year the OCESS holds a simulated manned space Mission. The astronauts are the five or six individuals who enter the habitat for the purposes of simulating space flight and exploration.
The astronaut positions are coveted amongst members of the OCESS as only a few positions are available, and those who go will always remember the experience. That however is only half the story (or a third if you ignore mission integrity) as two other groups of students exist within the OCESS (these being the Mission Control Staff, and the Simulator) providing an enjoyable experience for all. see Space Sim Groups
The purpose of astronauts is to collect data from experiments, simulate living in space and simulate how it is like to actualy have a mission for mission control. They are isolated from the outside world for the duration of the mission, during that time they will experience the trials and tribulations of space exploration.