psychology and how best to arrange experiment schedules for crews aboard space stations. Mir Mir was constructed between 1986 and 1996 and was the world's first modular space station. It was the first consistently inhabited long-term research station in space, and previously held the record for longest continuous human presence in space, at eight days short of ten years. Mir purpose was to provide a large and habitable scientific laboratory in space, and, through a number of collaborations, including Intercosmos and Shuttle–Mir, was made internationally accessible to cosmonauts and astronauts of many different countries. The station existed until March 23, 2001, at which point it was deliberately deorbited, and broke apart during atmospheric re-entry. Mir was based upon the Salyut series of space stations previously launched by the Soviet Union (seven Salyut space stations had been launched since 1971), and was mainly serviced by Russian-crewed Soyuz spacecraft and Progress cargo ships. The Buran space shuttle was anticipated to visit Mir, but its program was canceled after its first uncrewed spaceflight. Visiting US Space Shuttles used an Androgynous Peripheral Attach System docking collar originally designed for Buran, mounted on a bracket originally designed for use with the American Space Station Freedom. With the Space Shuttle docked to Mir, the temporary enlargements of living and working areas amounted to a complex that was the world's largest spacecraft at that time, with a combined mass of . Space Shuttle The Space Shuttle was a partially reusable low Earth orbital spacecraft system that was operated from 1981 to 2011 by the U.S. National Aeronautics and Space Administration (NASA) as part of the Space Shuttle program. Its official program name was Space Transportation System (STS), taken from a 1969 plan for a system of reusable spacecraft of which it was the only item funded for development. The first of four orbital test flights occurred in 1981, leading to operational flights beginning in 1982. In addition to the prototype, whose completion was cancelled, five complete Shuttle systems were built and used on a total of 135 missions from 1981 to 2011, launched from the Kennedy Space Center (KSC) in Florida. The Shuttle fleet's total mission time was 1322 days, 19 hours, 21 minutes and 23 seconds. The Space Shuttle carried large payloads to various orbits, and, during the Shuttle–Mir and ISS programs, provided crew rotation and carried various supplies, modules and pieces of equipment to the