On this day in 1986, the Soviet Union launched Mir, the first continuously inhabited long-term research station to orbit Earth. Assembled during orbit from 1986 to 1996, it had greater mass than any previous spacecraft at the time, and remained the largest satellite in orbit until 2001, when it was succeeded by the International Space Station (ISS).
The station served as a microgravity research laboratory where crews conducted experiments in biology, human biology, physics, astronomy, meteorology and spacecraft systems. The goal was to develop technologies that would further permanent human occupation of space.
Mir set the record for the longest continuous human presence in space at 3,644 days, until it was surpassed by the ISS in 2010. It hosted the record for the longest single human spaceflight: Valeri Polyakov spent over 437 days on the station between 1994 and 1995. Mir had the capacity to support a resident crew of three, or larger crews for short term visits.
Mir was launched as part of an effort to maintain a long-term research outpost in space. While the vast majority its crew was Russian, several international programs made it host to astronauts from the United States, Canada, Japan, and several European nations; the first Syrian and first Afghan in space were Mir visitors. These collaborative efforts were the precursor to the development of the ISS, which evolved from separate U.S., European, and Russian projects.
Following the collapse of the USSR, Mir came under the operation of the new Russian Federal Space Agency (Roscosmos). Although the station was fairly resilient, as evidenced by its impressive lifespan, its age was showing, and Russia at the time could not afford to update it. The station was subsequently decommissioned and deorbited in 2001.