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Mir (, ; ) was a space station operated in low Earth orbit from 1986 to 2001, first by the Soviet Union and later by the Russia. Mir was the first modular space station and was assembled in orbit from 1986 to 1996. It had a greater mass than any previous spacecraft. At the time it was the largest artificial satellite in orbit, succeeded by the International Space Station (ISS) after Mir's deorbiting. The station served as a microgravity laboratory in which crews conducted in biology, human biology, physics, astronomy, meteorology, and spacecraft systems with a goal of developing technologies required for permanent occupation of Outer space.
Mir was the first continuously inhabited long-term research station in orbit and held the record for the longest continuous human presence in space at 3,644 days, until it was surpassed by the ISS on 23 October 2010. It holds the record for the longest single human spaceflight, with Valeri Polyakov spending 437 days and 18 hours on the station between 1994 and 1995. Mir was occupied for a total of twelve and a half years out of its fifteen-year lifespan, having the capacity to support a resident crew of three, or larger crews for short visits.
Following the success of the Salyut programme, Mir represented the next stage in the Soviet Union's space station programme. The first module of the station, known as the core module or base block, was launched in 1986 and followed by six further modules. Proton were used to launch all of its components except for the docking module, which was installed by US Space Shuttle mission STS-74 in 1995. When complete, the station consisted of seven pressurised modules and several unpressurised components. Power was provided by several photovoltaic arrays attached directly to the modules. The station was maintained at an orbit between altitude and travelled at an average speed of , completing 15.7 orbits per day. (2025). 9780950659756, British Interplanetary Society. ISBN 9780950659756
The station was launched as part of the Soviet Union's crewed spaceflight programme effort to maintain a long-term research outpost in space, and following the collapse of the USSR, was operated by the new Russian Federal Space Agency (RKA). As a result, most of the station's occupants were Soviet; through international collaborations such as the Interkosmos, Euromir and Shuttle– Mir programmes, the station was made accessible to space travellers from several Asian, European and North American nations. Mir was deorbited in March 2001 after funding was cut off. The cost of the Mir programme was estimated by former RKA General Director Yuri Koptev in 2001 as $4.2 billion over its lifetime (including development, assembly and orbital operation).
It was originally planned that the ports would connect to modules derived from the Soyuz spacecraft. These modules would have used a Soyuz propulsion module, as in Soyuz and Progress, and the descent and orbital modules would have been replaced with a long laboratory module. Following a February 1979 governmental resolution, the programme was consolidated with Vladimir Chelomei's crewed Almaz military space station programme. The docking ports were reinforced to accommodate space station modules based on the TKS spacecraft. NPO Energia was responsible for the overall space station, with work subcontracted to KB Salyut, due to ongoing work on the Energia launch vehicle and Salyut 7, Soyuz-T, and Progress spacecraft. KB Salyut began work in 1979, and drawings were released in 1982 and 1983. New systems incorporated into the station included the Salyut 5B digital flight control computer and gyrodyne flywheels (taken from Almaz), Kurs automatic rendezvous system, Luch satellite communications system, Elektron oxygen generators, and Vozdukh carbon dioxide scrubbers.
By early 1984, work on Mir had halted while all resources were being put into the Buran programme in order to prepare the Buran spacecraft for flight testing. Funding resumed in early 1984 when Valentin Glushko was ordered by the Central Committee's Secretary for Space and Defence to orbit Mir by early 1986, in time for the 27th Communist Party Congress.
It was clear that the planned processing flow could not be followed and still meet the 1986 launch date. It was decided on Cosmonautics Day (12 April) 1985 to ship the flight model of the base block to the Baikonur Cosmodrome and conduct the systems testing and integration there. The module arrived at the launch site on 6 May, with 1100 of 2500 cables requiring rework based on the results of tests to the ground test model at Khrunichev. In October, the base block was rolled outside its cleanroom to carry out communications tests. The first launch attempt on 16 February 1986 was scrubbed when the spacecraft communications failed, but the second launch attempt, on 19 February 1986 at 21:28:23 UTC, was successful, meeting the political deadline.
The other two expansion modules, Kvant-1 in 1987 and the docking module in 1995, followed different procedures. Kvant-1, having, unlike the four modules mentioned above, no engines of its own, was launched attached to a tug based on the TKS spacecraft which delivered the module to the aft end of the core module instead of the docking node. Once hard docking had been achieved, the tug undocked and deorbited itself. The docking module, meanwhile, was launched aboard during STS-74 and mated to the orbiter's Orbiter Docking System. Atlantis then docked, via the module, to Kristall, then left the module behind when it undocked later in the mission. Various other external components, including three truss structures, several experiments and other unpressurised elements were also mounted to the exterior of the station by cosmonauts conducting a total of eighty spacewalks over the course of the station's history.
The station's assembly marked the beginning of the third generation of space station design, being the first to consist of more than one primary spacecraft (thus opening a new era in space architecture). First generation stations such as Salyut 1 and Skylab had monolithic designs, consisting of one module with no resupply capability; the second generation stations Salyut 6 and Salyut 7 comprised a monolithic station with two ports to allow consumables to be replenished by cargo spacecraft such as Progress. The capability of Mir to be expanded with add-on modules meant that each could be designed with a specific purpose in mind (for instance, the core module functioned largely as living quarters), thus eliminating the need to install all the station's equipment in one module.
| Mir Core Module (Core Module) | N/A | 19 February 1986 | Proton-K | Soviet Union | ||
| The base block for the entire Mir complex, the core module, or DOS-7, provided the main living quarters for resident crews and contained environmental systems, early attitude control systems and the station's main engines. The module was based on hardware developed as part of the , and consisted of a stepped-cylinder main compartment and a spherical 'node' module, which served as an airlock and provided ports to which four of the station's expansion modules were berthed and to which a Soyuz or Progress spacecraft could dock. The module's aft port served as the berthing location for Kvant-1. | ||||||
| Kvant-1 (Astrophysics Module) | EO-2 | 31 March 1987 | Proton-K | Soviet Union | ||
| The first expansion module to be launched, Kvant-1 consisted of two pressurised working compartments and one unpressurised experiment compartment. Scientific equipment included an X-ray telescope, an ultraviolet telescope, a wide-angle camera, high-energy X-ray experiments, an X-ray/gamma ray detector, and the Svetlana electrophoresis unit. The module also carried six Gyroscope for attitude control, in addition to life support systems including an Elektron oxygen generator and a Vozdukh carbon dioxide scrubber. | ||||||
| Kvant-2 (Augmentation Module) | EO-5 | 26 November 1989 | Proton-K | Soviet Union | ||
| The first TKS spacecraft based module, Kvant-2, was divided into three compartments: an EVA airlock, an instrument/cargo compartment (which could function as a backup airlock), and an instrument/experiment compartment. The module also carried a Soviet version of the Manned Maneuvering Unit for the Orlan space suit, referred to as Ikar, a system for regenerating water from urine, a shower, the Rodnik water storage system and six gyroscopes to augment those already located in Kvant-1. Scientific equipment included a high-resolution camera, spectrometers, X-ray sensors, the Volna 2 fluid flow experiment, and the Inkubator-2 unit, which was used for hatching and raising quail. | ||||||
| Kristall (Technology Module) | EO-6 | 31 May 1990 | Proton-K | Soviet Union | ||
| Kristall, the fourth module, consisted of two main sections. The first was largely used for materials processing (via various processing furnaces), astronomical observations, and a biotechnology experiment utilising the Aniur electrophoresis unit. The second section was a docking compartment which featured two APAS-89 docking ports initially intended for use with the Buran programme and eventually used during the Shuttle- Mir programme. The docking compartment also contained the Priroda 5 camera used for Earth resources experiments. Kristall also carried six control moment gyroscopes (CMGs, or "gyrodynes") for attitude control to augment those already on the station, and two collapsible solar arrays. | ||||||
| Spektr (Power Module) | EO-18 | 20 May 1995 | Proton-K | Russia | ||
| Spektr was the first of the three modules launched during the Shuttle- Mir programme; it served as the living quarters for American astronauts and housed NASA-sponsored experiments. The module was designed for remote observation of Earth's environment and contained atmospheric and surface research equipment. It featured four solar arrays which generated approximately half of the station's electrical power. The module also had a science airlock to expose experiments to the vacuum of space selectively. Spektr was rendered unusable following the collision with Progress M-34 in 1997 which damaged the module, exposing it to the vacuum of space. | ||||||
| Docking Module | EO-20 | 15 November 1995 | (STS-74) | US | ||
| The docking module was designed to help simplify Space Shuttle dockings to Mir. Before the first shuttle docking mission (STS-71), the Kristall module had to be tediously moved to ensure sufficient clearance between Atlantis and Mir's solar arrays. With the addition of the docking module, enough clearance was provided without the need to relocate Kristall. It had two identical APAS-89 docking ports, one attached to the distal port of Kristall with the other available for shuttle docking. This mission was the first time the Space Shuttle was used to attach a module to a space station. | ||||||
| Priroda (Earth Sensing Module) | EO-21 | 26 April 1996 | Proton-K | Russia | ||
| The seventh and final Mir module, Priroda's primary purpose was to conduct Earth resource experiments through remote sensing and to develop and verify remote sensing methods. The module's experiments were provided by twelve different nations, and covered microwave, visible, near infrared, and infrared spectral regions using both passive and active sounding methods. The module possessed both pressurised and unpressurised segments, and featured a large, externally mounted synthetic aperture radar dish. | ||||||
To assist in moving objects around the exterior of the station during EVAs, Mir featured two Strela cargo cranes mounted to the sides of the core module, used for moving spacewalking cosmonauts and parts. The cranes consisted of telescopic poles assembled in sections which measured around when collapsed, but when extended using a hand crank were long, meaning that all of the station's modules could be accessed during spacewalks.
Each module was fitted with external components specific to the experiments that were carried out within that module, the most obvious being the Travers antenna mounted to Priroda. This synthetic aperture radar consisted of a large dish-like framework mounted outside the module, with associated equipment within, used for Earth observations experiments, as was most of the other equipment on Priroda, including various radiometers and scan platforms. Kvant-2 also featured several scan platforms and was fitted with a mounting bracket to which the cosmonaut manoeuvring unit, or Ikar, was mated. This backpack was designed to assist cosmonauts in moving around the station and the planned Buran in a manner similar to the US Manned Maneuvering Unit, but it was only used once, during EO-5.
In addition to module-specific equipment, Kvant-2, Kristall, Spektr and Priroda were each equipped with one Lyappa arm, a robotic arm which, after the module had docked to the core module's forward port, grappled one of two fixtures positioned on the core module's docking node. The arriving module's docking probe was then retracted, and the arm raised the module so that it could be pivoted 90° for docking to one of the four radial docking ports.
The solar arrays themselves were launched and installed over a period of eleven years, more slowly than originally planned, with the station continually suffering from a shortage of power as a result. The first two arrays, each in area, were launched on the core module, and together provided a total of 9 kW of power. A third, dorsal panel was launched on Kvant-1 and mounted on the core module in 1987, providing a further 2 kW from a area. Kvant-2, launched in 1989, provided two long panels which supplied 3.5 kW each, whilst Kristall was launched with two collapsible, long arrays (providing 4 kW each) which were intended to be moved to Kvant-1 and installed on mounts which were attached during a spacewalk by the EO-8 crew in 1991.
This relocation was begun in 1995, when the panels were retracted and the left panel installed on Kvant-1. By this time all the arrays had degraded and were supplying much less power. To rectify this, Spektr (launched in 1995), which had initially been designed to carry two arrays, was modified to hold four, providing a total of of array with a 16 kW supply. Two further arrays were flown to the station on board the during STS-74, carried on the docking module. The first of these, the Mir cooperative solar array, consisted of American photovoltaic cells mounted on a Russian frame. It was installed on the unoccupied mount on Kvant-1 in May 1996 and was connected to the socket that had previously been occupied by the core module's dorsal panel, which was by this point barely supplying 1 kW. The other panel, originally intended to be launched on Priroda, replaced the Kristall panel on Kvant-1 in November 1997, completing the station's electrical system.
Attitude control was maintained by a combination of two mechanisms; in order to hold a set attitude, a system of twelve control moment gyroscopes (CMGs, or "gyrodynes") rotating at 10,000 rpm kept the station oriented, six CMGs being located in each of the Kvant-1 and Kvant-2 modules. When the attitude of the station needed to be changed, the gyrodynes were disengaged, thrusters (including those mounted directly to the modules, and the VDU thruster used for roll control mounted to the Sofora girder) were used to attain the new attitude and the CMGs were reengaged. This was done fairly regularly depending on experimental needs; for instance, Earth or astronomical observations required that the instrument recording images be continuously aimed at the target, and so the station was oriented to make this possible. Conversely, materials processing experiments required the minimisation of movement on board the station, and so Mir would be oriented in a gravity gradient attitude for stability. Prior to the arrival of the modules containing these gyrodynes, the station's attitude was controlled using thrusters located on the core module alone, and, in an emergency, the thrusters on docked Soyuz spacecraft could be used to maintain the station's orientation.
The atmosphere on Mir was similar to Earth's. Normal air pressure on the station was 101.3 kilopascal (14.7 psi); the same as at sea level on Earth. An Earth-like atmosphere offers benefits for crew comfort.
Only the last three of the programme's fourteen missions consisted of an expedition to Mir but none resulted in an extended stay in the station:
In September 1993, US Vice President Al Gore Jr., and Russian Prime Minister Viktor Chernomyrdin announced plans for a new space station, which eventually became the ISS. They also agreed, in preparation for this new project, that the United States would be heavily involved in the Mir programme as part of an international project known as the Shuttle–Mir Programme. The project, sometimes called "Phase One", was intended to allow the United States to learn from Russian experience in long-duration spaceflight and to foster a spirit of cooperation between the two nations and their space agencies, the US National Aeronautics and Space Administration (NASA) and the Russian Federal Space Agency (Roskosmos). The project prepared the way for further cooperative space ventures, specifically, "Phase Two" of the joint project, the construction of the ISS. The programme was announced in 1993; the first mission started in 1994, and the project continued until its scheduled completion in 1998. Eleven Space Shuttle missions, a joint Soyuz flight, and almost 1000 cumulative days in space for US astronauts occurred over the course of seven long-duration expeditions.
In their spare time, crews were able to catch up with work, observe the Earth below, respond to letters, drawings, and other items brought from Earth (and give them an official stamp to show they had been aboard Mir), or make use of the station's ham radio. Two amateur radio call signs, U1MIR and U2MIR, were assigned to Mir in the late 1980s, allowing amateur radio operators on Earth to communicate with the cosmonauts. The station was also equipped with a supply of books and films for the crew to read and watch.
NASA astronaut Jerry Linenger related how life on board Mir was structured and lived according to the detailed itineraries provided by ground control. Every second on board was accounted for and all activities were timetabled. After working some time on Mir, Linenger came to feel that the order in which his activities were allocated did not represent the most logical or efficient order possible for these activities. He decided to perform his tasks in an order that he felt enabled him to work more efficiently, be less fatigued, and suffer less from stress. Linenger noted that his comrades on Mir did not "improvise" in this way, and as a medical doctor he observed the effects of stress on his comrades that he believed was the outcome of following an itinerary without making modifications to it. Despite this, he commented that his comrades performed all their tasks in a supremely professional manner.
Astronaut Shannon Lucid, who set the record for longest stay in space by a woman while aboard Mir (surpassed by Sunita Williams 11 years later on the ISS), also commented about working aboard Mir: "I think going to work on a daily basis on Mir is very similar to going to work on a daily basis on an outstation in Antarctica. The big difference with going to work here is the isolation, because you really are isolated. You don't have a lot of support from the ground. You really are on your own."
To prevent some of these effects, the station was equipped with two (in the core module and Kvant-2) and a stationary bicycle (in the core module); each cosmonaut was to cycle the equivalent of and run the equivalent of per day. Cosmonauts used bungee cords to strap themselves to the treadmill. Researchers believe that exercise is a good countermeasure for the bone and muscle density loss that occurs in low-gravity situations.
Mir featured a shower, the Bania, located in Kvant-2. It was an improvement on the units installed in previous Salyut program stations, but proved difficult to use due to the time required to set up, use, and stow. The shower, which featured a plastic curtain and fan to collect water via an airflow, was later converted into a steam room; it eventually had its plumbing removed and the space was reused. When the shower was unavailable, crew members washed using wet wipes, with soap dispensed from a toothpaste tube-like container, or using a washbasin equipped with a plastic hood, located in the core module. Crews were also provided with rinse-less shampoo and edible toothpaste to save water.
On a 1998 visit to Mir, bacteria and larger organisms were found to have proliferated in water globules formed from moisture that had condensed behind service panels.
Some biologists were concerned about the mutant fungi being a major microbiological hazard for humans, and reaching Earth in the splashdown, after having been in an isolated environment for 15 years. On the other hand, some scientists are conducting research on whether this situation can be used for life in space. Scientists have discovered that fungi could actually assist space travel and detect livable environments for humankind in space. In fact, these resilient and frequently underestimated organisms might hold the key to our future on other planets. Fungi play a dramatic role in creating innovative and sustainable building materials. Most fungi possess Mycelium, hair-like root structures that grow and spread across surfaces. As mycelia expand, they bind surrounding materials, as wood chips, sawdust, or regolith (the loose material covering solid rock on planetary bodies like the Moon or Mars). This growth process results in a dense, interconnected network that creates a remarkably strong and durable substance. The resulting mycelium-based material offers notable thermal insulation and radiation protection, making it an ideal candidate for construction, particularly in severe environments like outer space or other interplanetary habitats.
Leonid Kizim and Vladimir Solovyov first docked with Mir on 15 March 1986. During their nearly 51-day stay on Mir, they brought the station online and checked its systems. They unloaded two Progress spacecraft launched after their arrival, Progress 25 and Progress 26.
On 5 May 1986, they undocked from Mir for a day-long journey to Salyut 7. They spent 51 days there and gathered 400 kg of scientific material from Salyut 7 for return to Mir. While Soyuz T-15 was at Salyut 7, the uncrewed Soyuz TM-1 arrived at the unoccupied Mir and remained for 9 days, testing the new Soyuz TM model. Soyuz T-15 redocked with Mir on 26 June and delivered the experiments and 20 instruments, including a multichannel spectrometer. The EO-1 crew spent their last 20 days on Mir conducting Earth observations before returning to Earth on 16 July 1986, leaving the new station unoccupied.
The second expedition to Mir, EO-2, launched on Soyuz TM-2 on 5 February 1987. During their stay, the Kvant-1 module, launched on 30 March 1987, arrived. It was the first experimental version of a planned series of '37K' modules scheduled to be launched to Mir on Buran. Kvant-1 was originally planned to dock with Salyut 7; due to technical problems during its development, it was reassigned to Mir. The module carried the first set of six gyroscopes for attitude control. The module also carried instruments for X-ray and ultraviolet astrophysical observations.
The initial rendezvous of the Kvant-1 module with Mir on 5 April 1987 was troubled by the failure of the onboard control system. After the failure of the second attempt to dock, the resident cosmonauts, Yuri Romanenko and Aleksandr Laveykin, conducted an EVA to fix the problem. They found a trash bag which had been left in orbit after the departure of one of the previous cargo ships and was now located between the module and the station, which prevented the docking. After removing the bag, docking was completed on 12 April.
The Soyuz TM-2 launch was the beginning of a string of 6 Soyuz launches and three long-duration crews between 5 February 1987 and 27 April 1989. This period also saw the first international visitors, Muhammed Faris (Syria), Abdul Ahad Mohmand (Afghanistan) and Jean-Loup Chrétien (France). With the departure of EO-4 on Soyuz TM-7 on 27 April 1989 the station was again left unoccupied.
After a 40-day delay caused by faulty computer chips, Kvant-2 was launched on 26 November 1989. After problems deploying the craft's solar array and with the automated docking systems on both Kvant-2 and Mir, the new module was docked manually on 6 December. Kvant-2 added a second set of control moment gyroscopes (CMGs, or "gyrodynes") to Mir, and brought the new life support systems for recycling water and generating oxygen, reducing dependence on ground resupply. The module featured a large airlock with a one-metre hatch. A special backpack unit (known as Ikar), an equivalent of the US Manned Maneuvering Unit, was located inside Kvant-2's airlock.
Soyuz TM-9 launched EO-6 crew members Anatoly Solovyev and Aleksandr Balandin on 11 February 1990. While docking, the EO-5 crew noted that three thermal blankets on the ferry were loose, potentially creating problems on reentry, but it was decided that they would be manageable. Their stay on board Mir saw the addition of the Kristall module, launched 31 May 1990. The first docking attempt on 6 June was aborted due to an attitude control thruster failure. Kristall arrived at the front port on 10 June and was relocated to the lateral port opposite Kvant-2 the next day, restoring the equilibrium of the complex. Due to the delay in the docking of Kristall, EO-6 was extended by 10 days to permit the activation of the module's systems and to accommodate an EVA to repair the loose thermal blankets on Soyuz TM-9.
Kristall contained furnaces for use in producing crystals under microgravity conditions (hence the choice of name for the module). The module was also equipped with biotechnology research equipment, including a small greenhouse for plant cultivation experiments which was equipped with a source of light and a feeding system, in addition to equipment for astronomical observations. The most obvious features of the module were the two Androgynous Peripheral Attach System (APAS-89) docking ports designed to be compatible with the Buran spacecraft. Although they were never used in a Buran docking, they were useful later during the Shuttle- Mir programme, providing a berthing location for US .
The EO-7 relief crew arrived aboard Soyuz TM-10 on 3 August 1990. The new crew arrived at Mir with quail for Kvant-2's cages, one of which laid an egg en route to the station. It was returned to Earth, along with 130 kg of experiment results and industrial products, in Soyuz TM-9. Two more expeditions, EO-8 and EO-9, continued the work of their predecessors whilst tensions grew back on Earth.
The first human mission flown from an independent Kazakhstan was Soyuz TM-14, launched on 17 March 1992, which carried the EO-11 crew to Mir, docking on 19 March before the departure of Soyuz TM-13. On 17 June, Russian President Boris Yeltsin and US President George H. W. Bush announced what would later become the Shuttle- Mir programme, a cooperative venture which proved useful to the cash-strapped Roskosmos (and led to the eventual completion and launch of Spektr and Priroda). EO-12 followed in July, alongside a brief visit by French astronaut Michel Tognini. The following crew, EO-13, began preparations for the Shuttle- Mir programme by flying to the station in a modified spacecraft, Soyuz TM-16 (launched on 26 January 1993), which was equipped with an APAS-89 docking system rather than the usual probe-and-drogue, enabling it to dock to Kristall and test the port which would later be used by US Space Shuttles. The spacecraft also enabled controllers to obtain data on the dynamics of docking a spacecraft to a space station off the station's longitudinal axis, in addition to data on the structural integrity of this configuration via a test called Rezonans conducted on 28 January. Soyuz TM-15, meanwhile, departed with the EO-12 crew on 1 February.
Throughout the period following the collapse of the USSR, crews on Mir experienced occasional reminders of the economic chaos occurring in Russia. The initial cancellation of Spektr and Priroda was the first such sign, followed by the reduction in communications as a result of the fleet of being withdrawn from service by Ukraine. The new Ukrainian government also vastly raised the price of the Kurs docking systems, manufactured in Russians' attempts to reduce their dependence on Kurs would later lead to accidents during TORU tests in 1997. Various Progress spacecraft had parts of their cargoes missing, either because the consumable in question had been unavailable, or because the ground crews at Baikonur had looted them. The problems became particularly obvious during the launch of the EO-14 crew aboard Soyuz TM-17 in July; shortly before launch there was a black-out at the pad, and the power supply to the nearby city of Baikonur failed an hour after launch. Nevertheless, the spacecraft launched on time and arrived at the station two days later. All of Mir's ports were occupied, and so Soyuz TM-17 had to station-keep 200 metres away from the station for half an hour before docking while Progress M-18 vacated the core module's front port and departed.
The EO-13 crew departed on 22 July, and soon after Mir passed through the annual Perseids meteor shower, during which the station was hit by several particles. A spacewalk was conducted on 28 September to inspect the station's hull, but no serious damage was reported. Soyuz TM-18 arrived on 10 January 1994 carrying the EO-15 crew (including Valeri Polyakov, who was to remain on Mir for 14 months), and Soyuz TM-17 left on 14 January. The undocking was unusual in that the spacecraft was to pass along Kristall in order to obtain photographs of the APAS to assist in the training of space shuttle pilots. Due to an error in setting up the control system, the spacecraft struck the station a glancing blow during the manoeuvre, scratching the exterior of Kristall.
On 3 February 1994, Mir veteran Sergei Krikalev became the first Russian cosmonaut to launch on a US spacecraft, flying on during STS-60.
The launch of Soyuz TM-19, carrying the EO-16 crew, was delayed due to the unavailability of a payload fairing for the booster that was to carry it, but the spacecraft eventually left Earth on 1 July 1994 and docked two days later. They stayed only four months to allow the Soyuz schedule to line up with the planned Space Shuttle manifest, and so Polyakov greeted a second resident crew in October, prior to the undocking of Soyuz TM-19, when the EO-17 crew arrived in Soyuz TM-20.
On 21 February 1996, the two-man EO-21 crew was launched aboard Soyuz TM-23, and they were soon joined by US crew member Shannon Lucid, who was brought to the station by Atlantis during STS-76. During this mission, the first joint US spacewalk on Mir took place, deploying the Mir Environmental Effects Payload package for the docking module. Lucid became the first American to carry out a long-duration mission aboard Mir with her 188-day mission, which set the US single spaceflight record. During Lucid's time aboard Mir, Priroda, the station's final module, arrived as did French visitor Claudie Haigneré flying the Cassiopée mission. The flight aboard Soyuz TM-24 also delivered the EO-22 crew of Valery Korzun and Aleksandr Kaleri.
On 16 September 1996, with the launch of Atlantis and the STS-79 flight, Lucid's stay aboard Mir ended. During this fourth docking, John Blaha transferred onto Mir to take his place as resident US astronaut. His stay on the station improved operations in a number of areas, including transfer procedures for a docked space shuttle, "hand-over" procedures for long-duration American crew members, and "ham" amateur radio communications, as well as two spacewalks to reconfigure the station's power grid. Blaha spent four months with the EO-22 crew before returning to Earth aboard Atlantis on STS-81 in January 1997, at which point he was replaced by physician Jerry Linenger. During his flight, Linenger became the first American to conduct a spacewalk from a foreign space station and the first to test the Russian-built Orlan-M spacesuit alongside Russian cosmonaut Vasili Tsibliyev, flying EO-23. All three crew members of EO-23 performed a "fly-around" in Soyuz TM-25 spacecraft. Linenger and his Russian crewmates Vasili Tsibliyev and Aleksandr Lazutkin faced several difficulties during the mission, including the most severe fire aboard an orbiting spacecraft (caused by a malfunctioning Vika), failures of various systems, a near collision with Progress M-33 during a long-distance TORU test and a total loss of station electrical power. The power failure also caused a loss of attitude control, which led to an uncontrolled "tumble" through space.
Linenger was succeeded by English-American astronaut Michael Foale, carried up by Atlantis on STS-84, alongside Russian mission specialist Elena Kondakova. Foale's increment proceeded fairly normally until 25 June when during the second test of the Progress manual docking system, TORU, Progress M-34 collided with solar arrays on the Spektr module and crashed into the module's outer shell, puncturing the module and causing depressurisation on the station. Only quick actions on the part of the crew, cutting cables leading to the module and closing Spektr's hatch, prevented the crews having to abandon the station in Soyuz TM-25. Their efforts stabilised the station's air pressure, whilst the pressure in Spektr, containing many of Foale's experiments and personal effects, dropped to a vacuum. In an effort to restore some of the power and systems lost following the isolation of Spektr and to attempt to locate the leak, EO-24 commander Anatoly Solovyev and flight engineer Pavel Vinogradov carried out a risky salvage operation later in the flight, entering the empty module during a so-called "intra-vehicular activity" or "IVA" spacewalk and inspecting the condition of hardware and running cables through a special hatch from Spektr's systems to the rest of the station. Following these first investigations, Foale and Solovyev conducted a 6-hour EVA outside Spektr to inspect the damage.
After these incidents, the US Congress and NASA considered whether to abandon the programme out of concern for the astronauts' safety, but NASA administrator Daniel Goldin decided to continue. The next flight to Mir, STS-86, carried David Wolf aboard Atlantis. During the orbiter's stay, Titov and Parazynski conducted a spacewalk to affix a cap to the docking module for a future attempt by crew members to seal the leak in Spektrs hull. Wolf spent 119 days aboard Mir with the EO-24 crew and was replaced during STS-89 with Andy Thomas, who carried out the last US expedition on Mir. The EO-25 crew arrived in Soyuz TM-27 in January 1998 before Thomas returned to Earth on the final Shuttle– Mir mission, STS-91.
The crew of EO-27, Viktor Afanasyev and Jean-Pierre Haigneré, arrived in Soyuz TM-29 on 22 February 1999 alongside Ivan Bella, who returned to Earth with Padalka in Soyuz TM-28. The crew carried out three EVAs to retrieve experiments and deploy a prototype communications antenna on Sofora. On 1 June it was announced that the deorbit of the station would be delayed by six months to allow time to seek alternative funding to keep the station operating. The rest of the expedition was spent preparing the station for its deorbit; a special analog computer was installed and each of the modules, starting with the docking module, was mothballed in turn and sealed off. The crew loaded their results into Soyuz TM-29 and departed Mir on 28 August 1999, ending a run of continuous occupation, which had lasted for eight days short of ten years. The station's control moment gyroscopes (CMGs, or "gyrodynes") and main computer were shut down on 7 September, leaving Progress M-42 to control Mir and refine the station's orbital decay rate.
Near the end of its life, there were plans for private interests to purchase Mir, possibly for use as the first orbital television/Film studio. The privately funded Soyuz TM-30 mission by MirCorp, that was launched on 4 April 2000, carried two crew members, Sergei Zalyotin and Aleksandr Kaleri, to the station for two months to do repair work with the hope of proving that the station could be made safe. This was to be the last crewed mission to Mir—while Russia was optimistic about Mir future, its commitments to the ISS project left no funding to support the aging station.
Mirs deorbit was carried out in three stages. The first stage involved waiting for atmospheric drag to orbital decay to an average of . This began with the docking of Progress M1-5, a modified version of the Progress-M carrying 2.5 times more fuel in place of supplies. The second stage was the transfer of the station into a orbit. This was achieved with two burns of Progress M1-5's control engines at 00:32 UTC and 02:01 UTC on 23 March 2001. After a two-orbit pause, the third and final stage of the deorbit began with the burn of Progress M1-5's control engines and main engine at 05:08 UTC, lasting 22+ minutes. Atmospheric reentry (arbitrarily defined beginning at AMSL) occurred at 05:44 UTC near Nadi, Fiji. Major destruction of the station began around 05:52 UTC and most of the unburned fragments fell into the South Pacific Ocean around 06:00 UTC.
Soyuz spacecraft provided personnel access to and from the station allowing for crew rotations and cargo return, and also functioned as a lifeboat for the station, allowing for a relatively quick return to Earth in the event of an emergency. Two models of Soyuz flew to Mir; Soyuz T-15 was the only Igla-equipped Soyuz-T to visit the station, whilst all other flights used the newer, Kurs-equipped Soyuz-TM. A total of 31 (30 crewed, 1 uncrewed) Soyuz spacecraft flew to the station over a fourteen-year period.
The uncrewed Progress cargo vehicles were only used to resupply the station, carrying a variety of cargoes including water, fuel, food and experimental equipment. The spacecraft were not equipped with reentry shielding and so, unlike their Soyuz counterparts, were incapable of surviving reentry. As a result, when its cargo had been unloaded, each Progress was refilled with rubbish, spent equipment and other waste which was destroyed, along with the Progress itself, on reentry. In order to facilitate cargo return, ten Progress flights carried VBK-Raduga capsules, which could return around 150 kg of experimental results to Earth automatically. Mir was visited by three separate models of Progress; the original 7K-TG variant equipped with Igla (18 flights), the Progress-M model equipped with Kurs (43 flights), and the modified Progress-M1 version (3 flights), which together flew a total of 64 resupply missions. Whilst the Progress spacecraft usually docked automatically without incident, the station was equipped with a remote manual docking system, TORU, in case problems were encountered during the automatic approaches. With TORU, cosmonauts could guide the spacecraft safely in to dock (with the exception of the catastrophic docking of Progress M-34, when the long-range use of the system resulted in the spacecraft striking the station, damaging Spektr and causing decompression).
In addition to the routine Soyuz and Progress flights, it was anticipated that Mir would also be the destination for flights by the Soviet Buran programme, which was intended to deliver extra modules (based on the same "37K" Satellite bus as Kvant-1) and provide a much improved cargo return service to the station. Kristall carried two Androgynous Peripheral Attach System (APAS-89) docking ports designed to be compatible with the shuttle. One port was to be used for Buran; the other for the planned Pulsar X-2 telescope, also to be delivered by Buran. The cancellation of the Buran programme meant these capabilities were not realised until the 1990s when the ports were used instead by US as part of the Shuttle- Mir programme (after testing by the specially modified Soyuz TM-16 in 1993). Initially, visiting Space Shuttle orbiters docked directly to Kristall, but this required the relocation of the module to ensure sufficient distance between the shuttle and Mirs solar arrays. To eliminate the need to move the module and retract solar arrays for clearance issues, a Mir Docking Module was later added to the end of Kristall. The shuttles provided crew rotation of the American astronauts on station and carried cargo to and from the station, performing some of the largest transfers of cargo of the time. With a space shuttle docked to Mir, the temporary enlargements of living and working areas amounted to a complex that was the largest spacecraft in history at that time, with a combined mass of .
Various breakdowns of the Elektron oxygen-generating system were a concern; they led crews to become increasingly reliant on the backup Vika solid-fuel oxygen generator (SFOG) systems, which led to a fire during the handover between EO-22 and EO-23. (see also ISS ECLSS)
The increased radiation levels pose a higher risk of crews developing cancer, and can cause damage to the of . These cells are central to the immune system and so any damage to them could contribute to the lowered immunity experienced by cosmonauts. Over time, in theory, lowered immunity results in the spread of infection between crew members, especially in such confined areas. To avoid this only healthy people were permitted aboard. Radiation has also been linked to a higher incidence of in cosmonauts. Protective shielding and protective drugs may lower the risks to an acceptable level, but data is scarce and longer-term exposure will result in greater risks.
At the low altitudes at which Mir orbited there is a variety of space debris, consisting of everything from entire spent and defunct , to explosion fragments, paint flakes, slag from solid rocket motors, coolant released by RORSAT nuclear powered satellites, small needles, and many other objects. These objects, in addition to natural , posed a threat to the station as they could puncture pressurised modules and cause damage to other parts of the station, such as the solar arrays. Micrometeoroids also posed a risk to spacewalking cosmonauts, as such objects could Space exposure, causing them to depressurise. Meteor showers in particular posed a risk, and, during such storms, the crews slept in their Soyuz ferries to facilitate an emergency evacuation should Mir be damaged.
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