The main body of the Mir space station consisted of four areas: a docking compartment, living quarters, a work area, and a propulsion chamber. The docking compartment contained television equipment, the electric power supply system, and five of the vessel’s six docking ports. The work area was the spacecraft’s nerve center and contained the main navigational, communications, and power controls. At one end of the station, the unpressurized propulsion compartment contained the station’s rocket motors, fuel supply, heating system, and the sixth docking port to receive unpiloted refueling missions.

As modules were added to the station, Mir continued to gain mass and functionality. An observatory module with ultraviolet, X-ray, and gamma-ray telescopes was added in 1987; a module with two solar panel arrays and an airlock was added next in 1989; and a scientific module was added in 1990. In 1995 two more modules were added, one of which was a docking module carried to the station by the space shuttle Atlantis; and a remote Earth-sensing module was added in 1996.