Mir – a manned space station built by the Soviet Union, which orbited the Earth in low Earth orbit from the launch of its first module in 1986 until its controlled deorbit in 2001. In the first years of its existence, Mir was used only by the USSR and its partner countries under the Interkosmos program. After the collapse of the USSR, astronauts of other nationalities, including those from the United States, also began flying to the station.
Mir was the largest man-made structure in orbit until the creation of the ISS and is considered, alongside the launch of Sputnik 1 in 1957 and Yuri Gagarin’s flight in 1961, among the greatest achievements of Soviet cosmonautics.
Construction and design
Mir was the first space station built for scientific and experimental purposes. In the 1970s and 1980s, the Soviet Union launched several Salyut-type stations into space; however, besides scientific purposes, they were also used for military tasks. Salyut stations remained in orbit for about 4 years and were made of a single module, whereas Mir was built from several modules launched separately and later assembled in orbit. Almost all Mir station modules were launched from the Baikonur Cosmodrome using the Proton rocket. Only the shuttle docking module was carried by the space shuttle Atlantis from the Kennedy Space Center.
For many years, Mir remained humanity’s only outpost in space. Alongside many scientific experiments conducted here, significant experience was also gained regarding long-term human stays in outer space. Several cosmonauts stayed on the station for longer than one year.
The modular design of Mir was adopted for the construction of the International Space Station, and the Zvezda module of the ISS is a modified version of the station’s main module.
Core Module (DOS)
The Mir core module (also called the main module) was launched on February 19, 1986. It featured six docking ports, to which other modules were attached (5 ports) and where spacecraft docked (1 port).
DOS served the crew as a living module and was equipped with sanitary facilities (e.g., a toilet), station controls, and communication systems with Earth. Its launch mass was 20.4 tons. The core module was 13.3 m long and 4.2 m in diameter. Power was obtained from solar panels. When the docking adapter (located at the front of the module) was free, it was possible to exit the station through it and perform spacewalks.
Kvant Scientific Module
The Kvant module was launched on March 31, 1987, and docked with the station after a delay on April 9, becoming the first module to expand Mir. Unlike the rest of the modules, Kvant did not dock to the docking adapter but to the port at the rear of the core module. A day later, cosmonauts entered the new module and began its full activation.
Kvant was used for scientific work, mainly in the field of physics. The launch mass of the module was 11 tons, its length was 5.3 m, and its diameter was 4.35 m. Kvant had two docking ports, one used for connection with the main station module and the second for connection with Soyuz and Progress ships. Thanks to a system of pipes and pumps in the module, it was possible to transfer fuel from Progress ships to the core module.
Kvant 2 Scientific Module
The Kvant 2 module was launched on November 26, 1989, and attached to the side port of the docking adapter ten days later. It was used for Earth observation and biotechnological experiments. Additionally, it was equipped with crew personal hygiene systems, life support, and an improved airlock. Solar panels provided power. The launch mass was 19.6 t, and the module’s length was 12.2 m.
Kristall Scientific Module
The Kristall scientific module (also known as Kvant 3) was launched on May 31, 1990, and connected with the station 10 days later. It docked to the docking adapter opposite the Kvant 2 module. Kristall was used for biological experiments as well as those involving various types of materials. It had two additional docking ports, which were planned to be used for Buran space shuttle flights and for mounting a special telescope. However, these plans failed. Nevertheless, on June 27, 1995, the shuttle Atlantis docked to this module, bringing a special docking port for space shuttles. To enable the docking of American space shuttles, the module was moved to the bottom port of the docking adapter, which provided space for the Spektr module. Kristall had the same mass and dimensions as Kvant 2 and, like it, featured solar panels.
Spektr Scientific Module
On May 20, 1995, another Mir module named Spektr was launched. It connected to the station 12 days later at the free side port of the docking adapter (opposite the Kvant 2 module), which Kristall had previously vacated. Spektr was equipped with instruments for studying the Earth’s atmosphere, geophysical processes, and cosmic radiation. For the first time, it was equipped with NASA scientific equipment, which was used during the Shuttle-Mir program. With solar panels arranged in an X-shape, it stood out significantly from the other station modules. The launch mass was 20 t, and the length was 14 m, which gave Spektr the title of the longest module of the station. During an accident involving Progress on June 25, 1997, it was so severely damaged that it could only be used to power the station.
Shuttle Docking Module
The docking module for American shuttles was carried into space aboard the shuttle Atlantis from the Kennedy Space Center on November 13, 1995. Three days later, it was connected to the Kristall module. The Shuttle Docking Module was 4.7 m long. It facilitated shuttle docking similarly to the planned module for the Buran shuttle. It was used by orbiters 8 times during 11 missions under the Shuttle-Mir program (one mission docked directly to the Kristall module, and two only approached the station without docking). A modified version of the Androgynous Peripheral Attach System (originally designed for the Soyuz-Apollo flight) known as APAS-89 was used for docking.
Priroda Experimental Module
Priroda Module and Mir Expansion
The Priroda module launched on April 23, 1996, and docked three days later with the upper docking port, opposite the Kristall module. It was the final module used to expand the Mir station.
Priroda was equipped with instruments for microgravity research. It was 12 meters long with a mass of 19 tons, and visually resembled the Kvant-2 and Kristall modules. The module contained battery systems intended to serve as a backup power supply; however, due to problems in orbit, the batteries failed, allowing only one attempt to dock with the station. Despite concerns (as most previous modules required more than one docking attempt), the operation proceeded without issues.
By the end of Mir’s expansion, the station had a mass of over 135 tons and measured 31 m in width and 33 m in length.
Exploitation
A total of 96 cosmonauts visited the Mir space station. 19 of them stayed twice, while Aleksandr Viktorenko and Anatoly Solovyev visited five times. Valeri Polyakov stayed on the station the longest – 679 days. From January 1994 to May 1995, he set a record for the amount of time spent in space during a single mission – 438 days. Such long stays on the station primarily served research on the long-term effects of human presence in space.
There were 22 Soyuz spacecraft flights and 9 American space shuttle flights.
In 1990, Japanese journalist Toyohiro Akiyama flew to the station, followed a year later by Austrian astronaut Franz Viehböck.
The astronauts of the Soyuz TM-13 mission, Aleksandr Volkov and Toktar Aubakirov, arrived at the station as Soviet cosmonauts and returned as Russians. During their stay, the USSR was dissolved. Because of this, the crew’s stay was extended by half a year. The mission concluded on March 25, 1992.
1992 – 1999
Following political changes in the republics of the Soviet Union, more and more astronauts from Western European countries and the United States visited the station, which remained under Russian supervision. With the arrival of the EO-11 mission, a new „era” also began for Russian cosmonautics.
In 1992, 1994, and 1997, three German astronauts visited the station: Klaus-Dietrich Flade, Ulf Merbold, and Reinhold Ewald, respectively. In 1997, French astronaut Michel Tognini was also on the station.
Simultaneously, for the further expansion of the station, the first American aboard a Soyuz spacecraft – Norman Thagard – launched from Baikonur in 1995. In June of that year, the first of 11 shuttle missions under the Shuttle-Mir program began. In September, Thomas Reiter, a German ESA astronaut who spent 179 days on the station, arrived. In 1996, the station’s expansion was completed with the attachment of the Priroda module.
Final Years
On November 20, 1998, Zarya launched – the first module of the International Space Station (ISS). Russia was also involved in its construction, which meant their budget was insufficient to maintain two space stations simultaneously. Foreign partners also lacked adequate funds to keep Mir in orbit. In 1999, MirCorp was established in the Netherlands – an enterprise that aimed to use private funds to keep the Mir station in orbit and utilize it for commercial purposes (space tourism).
Between July 23–28, 1999, a Russian-Georgian radio-technical experiment called Reflektor operated on board, in the form of a 6.5-meter reflector antenna attached to the Sofora truss mast.
On April 4, 2000, the final crew launched to the Mir station aboard the Soyuz TM-30, after the station had not hosted an astronaut for 7 months. The mission, funded by MirCorp, lasted 72 days and was the 39th crewed flight to Mir. Cosmonauts Sergei Zalyotin and Aleksandr Kaleri performed repair work. Roskosmos, during the crew’s return in June 2000, still believed it would be possible to keep the station in orbit for at least two more years thanks to private investor funding. However, the costs of maintaining the station proved too high. On October 23, 2000, the Russian space agency decided to deorbit the station.
Deorbiting
Mir was removed from orbit on March 23, 2001. It had been a temporary home for numerous cosmonauts, astronauts, and guests from other space agencies. The descent from orbit began on January 24, 2001, with the launch of the uncrewed Progress M1-5 transport ship, which also carried the extra fuel needed for the braking procedure starting a few weeks later. At a designated time, the Progress engines fired three times to slow Mir down, simultaneously changing its orbit from circular to elliptical with an apogee of 220 km and a perigee of 160 km. Once the orbit correction was made, the atmospheric entry program began. The final deceleration reduced the station’s speed by 17.3 m/s, which was enough for it to descend into the upper layers of the atmosphere. In the early morning hours of March 23, 2001, the Mir station was deorbited. The station entered the upper atmosphere, burning up due to friction. Unburned fragments fell into the Pacific Ocean at 6:57 UTC near the Fiji Islands. The only things left of it are the items thrown directly into orbit by cosmonauts, which now form part of the space debris.
In its 15-year history (even though its lifespan was planned for 7 years), Mir orbited the Earth 86,067 times, flying at an altitude of about 390 km and traveling 3,638,470,307 km. 78 spacewalks were conducted on it.
Over 16,500 scientific experiments were performed on Mir, including those preparing future technologies and procedures, such as space tethers or laser communication systems, and testing the capabilities of future space stations.
Flights to Mir
There were 39 crewed spaceflights to the Mir station and two that approached it. 109 astronauts of various nationalities (mainly Russian and American) participated. Dozens of uncrewed transport missions also flew to the station.
Soyuz
Soyuz spacecraft were the primary means of transporting crews to Mir. They performed 30 missions to the station, involving 56 astronauts (36 Russian and 18 of other nationalities). Soyuz ships also served as „lifeboats” for the crew. While a crew was on board Mir, the Soyuz could ensure a safe return to Earth in case of danger.
Russian missions primarily used the Soyuz-TM generation (except for the first mission, which used a Soyuz-T). This version featured a new docking system – Kurs, a new engine, and an improved landing system.
Space Shuttles
The STS-71 mission of the shuttle Atlantis, which launched on June 27, 1995, was the first space shuttle to dock with the Mir station. American shuttles performed a total of nine missions to the orbital complex and two that only approached it. Except for the first mission, all docked using a specially designed module. The shuttles brought a total of 53 people to the station (44 Americans, 6 Russians, 2 French, and one Canadian citizen).
Shuttles were mainly used for crew exchange and bringing small equipment items and experiments. The shuttle Atlantis performed 7 missions to Mir, while Discovery and Endeavour performed one each.
Progress
Progress transport ships were used to bring supplies essential for long-term stays in space and to deliver fuel for the station. Additionally, they carried experiments, spare parts, and some station equipment. The final Progress ship was used to deorbit Mir.
