Mir was the first modular space station, built from 1986 to 1996 under the auspices of the Soviet Union and Russia at an estimated cost of $4.2 billion. Planning for Mir began as early as 1976 as an extension of the Salyut space station program, and its components were launched as pre-assembled pieces and joined together in orbit.

Operated from 1986 to 2001 with a series of long duration crews for most of 86,330 laps around the planet, Mir was a laboratory for experimental research on technology that would make a permanent human presence in space possible. It became an international research center, housing 104 astronauts, of whom 62 were not Russian, and the site of 23,000 experiments.

Although by its last years, Mir had developed a poor reputation for safety and maintenance, its larger legacy was one of accomplishment, as it signaled the possibilities for long-term human exploration in space. Mir would be succeeded by the International Space Station, launched by the United Stations in cooperation with fifteen other nations.