The Soviet Union’s Salyut space station was succeeded by a modular space station, Mir, which was used for more than a decade as new laboratory and power modules. Launched in February 1986, the Mir was designed to house more cosmonauts on longer stays than the Salyut could support. The core of the Mir was the "base block" living quarters, which had six docking ports for spacecraft and other modules. Mir could be expanded by adding laboratory equipment and modules, rearranged for different missions, and upgraded without abandoning the original core…