The Apollo spacecraft that sent American astronauts to the moon had two modules, the command module and the service module.
The command module, where the three astronauts spent their time, measured 10 feet (3 m) x 12.5 feet (3.8 m).
It had five windows and contained three couches for the astronauts; storage facilities; navigation, instrument, and control panels; space suits; food; and toiletries.
The command module was linked to the lunar module by an air lock reached through a short tunnel.
It was at this air lock that the astronauts in the lunar module had to disengage from and link back up with the spacecraft.
The service module was about 13 feet (3.9 m) x 25 feet (7.5 m).
It held rockets to reach lunar orbit and to begin reentry; equipment bays; scientific instruments; cameras; and electrical and life-support systems.
There was an identical duplicate of every kind of life-support system in case of emergency.