The members of Spacesim are usually divided into one of three groups: the simulators, the astronauts and Mission Control. Each group has a specific task to perform and they work together to make the Space Sim experience as real as it can possibly be.
- Main article: Astronauts
Astronauts are members who volunteer to live within the Habitat for the duration of a mission. They get to experience life in space as much as is possible within the simulation. Removed from the rest of the world, they conduct experiments and spacewalks to fulfil the purpose of each mission, and are the pioneers who land on new worlds in the name of the OCESS.
- Main article: Simulators
Simulators are the hidden part of Spacesim. The members of this clandestine workforce are kept secret from the rest of Spacesim as they work to simulate the space experience. They are responsible for meteor storms, solar flares, and other natural occurrences that make the mission seem realistic. To express it in Dungeons and Dragons terms: The simulators are the Dungeon Masters.
- Main article: Mission Control
Mission Control is the earthly headquarters of the mission. Astronauts report all findings to the Mission Control staff and consult them for advice. Mission Control also monitors the progress of the mission, provides the astronauts with data and feedback on their progress, and recommends courses of action in case something goes wrong.
- Main article: Alumni
Not really a group of Spacesim members, but too important to be left out, the alumni group (as the term implies) consist of past Spacesim members who still have an interest in Spacesim. They continue to assist the current members whether dropping in to Work Sessions, providing advice and knowledge, or just showing us how it was done "back in the day". Though they are not members per se, Spacesim owes them quite a bit.