Mir

This article is about the Soviet/Russian space station. For other uses, seeMir (disambiguation).

Mir

Mirseen fromSpace ShuttleEndeavourduringSTS-89(28 January 1998)
Mirinsignia
Station statistics
COSPAR ID	1986-017A
SATCATno.	16609
Call sign	Mir
Crew	3
Launch	20 February 1986–23 April 1996
Launch pad	Baikonur200/39 Baikonur81/23 KennedyLC-39A
Reentry	23 March 2001, 05:59UTC
Mass	129,700 kg (285,940lb)
Length	19 m (62.3 ft) from Core module toKvant-1
Width	31 m (101.7 ft) fromPrirodato Docking module
Height	27.5 m (90.2 ft) fromKvant-2 toSpektr
Pressurisedvolume	350 m3(12,000 cu ft)
Atmospheric pressure	c. 101.3kPa(29.91inHg,1atm)
Periapsis altitude	354 km (189nmi)AMSL${\bar {x}}\!\,$
Apoapsis altitude	374 km (216 nmi) AMSL${\bar {x}}\!\,$
Orbital inclination	51.6degrees
Orbital speed	7.7 km/s (27,700 km/h, 17,200 mph)
Orbital period	91.9 minutes${\bar {x}}\!\,$
Orbits per day	15.7${\bar {x}}\!\,$
Days in orbit	5,511 (15 years and 32 days)
Days occupied	4,592
No.of orbits	86,331
Statistics as of 23 March 2001 (unless noted otherwise) References:
Configuration
Station elements as of May 1996

Mir(‹See Tfd›Russian:Мир,IPA:[ˈmʲir];lit. 'peace'or'world') was aspace stationoperated inlow Earth orbitfrom 1986 to 2001, first by theSoviet Unionand later by theRussian Federation.Mirwas the first modular space station and was assembled in orbit from 1986 to 1996. It had a greater mass than any previousspacecraft.At the time it was the largestartificial satellitein orbit, succeeded by theInternational Space Station(ISS) afterMir'sorbit decayed.The station served as amicrogravityresearchlaboratoryin which crews conductedexperimentsinbiology,human biology,physics,astronomy,meteorology,and spacecraft systems with a goal of developing technologies required for permanent occupation ofspace.

Mirwas the first continuously inhabited long-term research station in orbit and held the record for the longest continuoushuman presence in spaceat 3,644 days, until it was surpassed by the ISS on 23 October 2010.It holds the record for the longest single human spaceflight, withValeri Polyakovspending 437 days and 18 hours on the station between 1994 and 1995.Mirwas 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 theSalyut programme,Mirrepresented the next stage in the Soviet Union's space station programme. The first module of the station, known as thecore moduleor base block, was launched in 1986 and followed by six further modules.Protonrocketswere used to launch all of its components except for thedocking module,which was installed by USSpace ShuttlemissionSTS-74in 1995. When complete, the station consisted of seven pressurised modules and several unpressurised components. Power was provided by severalphotovoltaic arraysattached directly to the modules. The station wasmaintained at an orbitbetween 296 km (184 mi) and 421 km (262 mi) altitude and travelled at an average speed of 27,700 km/h (17,200 mph), completing 15.7 orbits per day.

The station was launched as part of the Soviet Union'screwed spaceflight programmeeffort to maintain a long-term research outpost in space, and following the collapse of the USSR, was operated by the newRussian Federal Space Agency(RKA). As a result, most of the station's occupants were Soviet; through international collaborations such as theInterkosmos,EuromirandShuttle–Mirprogrammes, the station was made accessible to space travellers from several Asian, European and North American nations.Mirwas deorbitedin March 2001 after funding was cut off. The cost of theMirprogramme was estimated by former RKA General DirectorYuri Koptevin 2001 as $4.2 billion over its lifetime (including development, assembly and orbital operation).

Origins

Mirwas authorised by a 17 February 1976 decree, to design an improved model of theSalyutDOS-17K space stations. Four Salyut space stations had been launched since 1971, with three more being launched duringMir's development. It was planned that the station's core module (DOS-7and the backupDOS-8) would be equipped with a total of four docking ports; two at either end of the station as with the Salyut stations, and an additional two ports on either side of a docking sphere at the front of the station to enable further modules to expand the station's capabilities. By August 1978, this had evolved to the final configuration of one aft port and five ports in a spherical compartment at the forward end of the station.

It was originally planned that the ports would connect to 7.5-tonne (8.3-short-ton) modules derived from theSoyuz spacecraft.These modules would have used a Soyuz propulsion module, as in Soyuz andProgress,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 withVladimir Chelomei's crewedAlmazmilitary space station programme. The docking ports were reinforced to accommodate 20-tonne (22-short-ton) space station modules based on theTKS spacecraft.NPO Energiawas responsible for the overall space station, with work subcontracted toKB Salyut,due to ongoing work on theEnergiarocketandSalyut 7,Soyuz-T,andProgress 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,Luchsatellitecommunications system,Elektronoxygen generators, andVozdukhcarbon dioxide scrubbers.

By early 1984, work onMirhad halted while all resources were being put into theBuran programmein order to prepare theBuranspacecraftfor flight testing. Funding resumed in early 1984 whenValentin Glushkowas ordered by theCentral Committee's Secretary for Space and Defence to orbitMirby early 1986, in time for the27th 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 onCosmonaut's Day(12 April) 1985 to ship the flight model of thebase blockto theBaikonur Cosmodromeand 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 atKhrunichev.In October, the base block was rolled outside itscleanroomto 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.

Station structure

Assembly

A diagram showing theKonusdrogue and module movements aroundMir's docking node

The orbital assembly ofMirbegan on 19 February 1986 with the launch of theProton-Krocket. Four of the six modules which were later added (Kvant-2in 1989,Kristallin 1990,Spektrin 1995 andPrirodain 1996) followed the same sequence to be added to the mainMircomplex. Firstly, the module would be launched independently on its own Proton-K and chase the station automatically. It would then dock to the forward docking port on the core module's docking node, then extend itsLyappa armto mate with a fixture on the node's exterior. The arm would then lift the module away from the forward docking port and rotate it on to the radial port where it was to mate, before lowering it to dock. The node was equipped with only twoKonusdrogues, which were required for dockings. This meant that, prior to the arrival of each new module, the node would have to be depressurised to allow spacewalking cosmonauts to manually relocate the drogue to the next port to be occupied.

The other two expansion modules,Kvant-1in 1987 and thedocking modulein 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 theTKS spacecraftwhich 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 aboardSpace ShuttleAtlantisduringSTS-74and mated to the orbiter'sOrbiter Docking System.Atlantisthen docked, via the module, toKristall,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 inspace architecture). First generation stations such asSalyut 1andSkylabhad monolithic designs, consisting of one module with no resupply capability; the second generation stationsSalyut 6andSalyut 7comprised a monolithic station with two ports to allow consumables to be replenished by cargo spacecraft such asProgress.The capability ofMirto 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.

Pressurised modules

In its completed configuration, the space station consisted of seven different modules, each launched into orbit separately over a period of ten years by eitherProton-Krockets orSpace ShuttleAtlantis.

Module	Expedition	Launch date	Launch system	Nation	Isolated view	Station view
Mir Core Module (Core Module)	N/A	19 February 1986	Proton-K	Soviet Union
	The base block for the entireMircomplex, 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 theSalyut programme,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 forKvant-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 anX-ray telescope,anultraviolet 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 sixgyrodynesfor attitude control, in addition to life support systems including anElektronoxygen generator and aVozdukhcarbon dioxide scrubber.
Kvant-2 (Augmentation Module)	EO-5	26 November 1989	Proton-K	Soviet Union
	The firstTKSbased module,Kvant-2, was divided into three compartments: anEVAairlock, an instrument/cargo compartment (which could function as a backup airlock), and an instrument/experiment compartment. The module also carried a Soviet version of theManned Maneuvering Unitfor theOrlan space suit,referred to asIkar,a system for regenerating water from urine, a shower, theRodnikwater storage system and sixgyrodynesto augment those already located inKvant-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 raisingquail.
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 twoAPAS-89docking portsinitially intended for use with theBuranprogrammeand eventually used during theShuttle-Mirprogramme.The docking compartment also contained the Priroda 5 camera used for Earth resources experiments.Kristallalso carried sixcontrol 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
	Spektrwas the first of the three modules launched during the Shuttle-Mirprogramme; it served as the living quarters for American astronauts and housedNASA-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.Spektrwas rendered unusable following the collision withProgress M-34in 1997 which damaged the module, exposing it to the vacuum of space.
Docking Module	EO-20	15 November 1995	Space ShuttleAtlantis (STS-74)	US
	The docking module was designed to help simplifySpace ShuttledockingstoMir.Before the first shuttle docking mission (STS-71), theKristallmodule had to be tediously moved to ensure sufficient clearance betweenAtlantisandMir's solar arrays. With the addition of the docking module, enough clearance was provided without the need to relocateKristall.It had two identicalAPAS-89docking ports, one attached to the distal port ofKristallwith the other available for shuttle docking.
Priroda (Earth Sensing Module)	EO-21	26 April 1996	Proton-K	Russia
	The seventh and finalMirmodule,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 mountedsynthetic aperture radardish.

Unpressurised elements

The Travers radar antenna,Soforagirder, VDU thruster block, SPK unit and aStrelacrane, alongsideKvant-2andPriroda

In addition to the pressurised modules,Mirfeatured several external components. The largest component was theSoforagirder, a large scaffolding-like structure consisting of 20 segments which, when assembled, projected 14 metres from its mount onKvant-1. A self-contained thruster block, the VDU (Vynosnaya Dvigatyelnaya Ustanovka), was mounted on the end ofSoforaand was used to augment the roll-control thrusters on the core module. The VDU's increased distance fromMir's axis allowed an 85% decrease in fuel consumption, reducing the amount of propellant required to orient the station.A second girder,Rapana,was mounted aft ofSoforaonKvant-1. This girder, a small prototype of a structure intended to be used onMir-2to hold large parabolic dishes away from the main station structure, was 5 metres long and used as a mounting point for externally mounted exposure experiments.

To assist in moving objects around the exterior of the station duringEVAs,Mirfeatured twoStrelacargo cranesmounted 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 1.8 metres (6 ft) when collapsed, but when extended using a hand crank were 14 metres (46 ft) 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 toPriroda.Thissynthetic aperture radarconsisted 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 onPriroda,including various radiometers and scan platforms.Kvant-2 also featured several scan platforms and was fitted with a mounting bracket to which thecosmonaut manoeuvring unit,orIkar,was mated. This backpack was designed to assist cosmonauts in moving around the station and the plannedBuranin a manner similar to the USManned Maneuvering Unit,but it was only used once, duringEO-5.

In addition to module-specific equipment,Kvant-2,Kristall,SpektrandPrirodawere each equipped with oneLyappaarm,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.

Power supply

The four solar arrays onSpektr

Photovoltaic (PV) arrayspoweredMir.The station used a 28voltDCsupply which provided 5-, 10-, 20- and 50-amptaps. When the station was illuminated by sunlight, several solar arrays mounted on the pressurised modules provided power toMir's systems and charged thenickel-cadmium storage batteriesinstalled throughout the station.The arrays rotated in only one degree of freedom over a 180° arc, and tracked the Sun usingSun sensorsand motors installed in the array mounts. The station itself also had to be oriented to ensure optimum illumination of the arrays. When the station's all-sky sensor detected thatMirhad entered Earth's shadow, the arrays were rotated to the optimum angle predicted for reacquiring the Sun once the station passed out of the shadow. The batteries, each of 60Ahcapacity, were then used to power the station until the arrays recovered their maximum output on the day side of Earth.

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 38 m²(409 ft²) in area, were launched on the core module, and together provided a total of 9 kW of power. A third,dorsalpanel was launched onKvant-1 and mounted on the core module in 1987, providing a further 2 kW from a 22 m²(237 ft²) area.Kvant-2, launched in 1989, provided two 10 m (32.8 ft) long panels which supplied 3.5 kW each, whilstKristallwas launched with two collapsible, 15 m (49.2 ft) long arrays (providing 4 kW each) which were intended to be moved toKvant-1 and installed on mounts which were attached during a spacewalk by theEO-8crew in 1991.

This relocation was begun in 1995, when the panels were retracted and the left panel installed onKvant-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 126 m²(1360 ft²) of array with a 16 kW supply.Two further arrays were flown to the station on board theSpace ShuttleAtlantisduringSTS-74,carried on the docking module. The first of these, theMircooperative solar array, consisted of American photovoltaic cells mounted on a Russian frame. It was installed on the unoccupied mount onKvant-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 onPriroda,replaced theKristallpanel onKvant-1 in November 1997, completing the station's electrical system.

Orbit control

Graph showing the changing altitude ofMirfrom 19 February 1986 until 21 March 2001

Mirwas maintained in a near circular orbit with an average perigee of 354 km (220 mi) and an average apogee of 374 km (232 mi), travelling at an average speed of 27,700 km/h (17,200 mph) and completing 15.7 orbits per day.As the station constantly lost altitude because of slightatmospheric drag,it needed to be boosted to a higher altitude several times each year. This boost was generally performed by Progress resupply vessels, although during the Shuttle-Mirprogramme the task was performed by US Space Shuttles, and, prior to the arrival ofKvant-1,the engines on the core module could also accomplish the task.

Attitude control was maintained by a combination of two mechanisms; in order to hold a set attitude, a system of twelvecontrol moment gyroscopes(CMGs, or "gyrodynes" ) rotating at 10,000rpmkept the station oriented, six CMGs being located in each of theKvant-1andKvant-2modules.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 theSoforagirder) 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 soMirwould be oriented in agravity gradientattitude 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.

Communications

Radio communicationsprovidedtelemetryand scientific data links betweenMirand theRKA Mission Control Centre(TsUP). Radio links were also used duringrendezvous and docking proceduresand for audio and video communication between crew members, flight controllers and family members. As a result,Mirwas equipped with several communication systems used for different purposes. The station communicated directly with the ground via theLiraantennamounted to thecore module.TheLiraantenna also had the capability to use theLuchdata relay satellite system (which fell into disrepair in the 1990s) and the network of Soviettracking shipsdeployed in various locations around the world (which also became unavailable in the 1990s).UHF radiowas used by cosmonauts conductingEVAs.UHF was also employed by other spacecraft that docked to or undocked from the station, such as Soyuz, Progress, and the Space Shuttle, in order to receive commands from the TsUP andMircrew members via theTORUsystem.

Microgravity

AtMir's orbital altitude, the force of Earth's gravity was 88% of sea level gravity. While the constant free fall of the station offered a perceived sensation ofweightlessness,the onboard environment was not one of weightlessness or zero gravity. The environment was often described asmicrogravity.This state of perceived weightlessness was not perfect, being disturbed by five separate effects:

• The drag resulting from the residual atmosphere;
• Vibratory acceleration caused by mechanical systems and the crew on the station;
• Orbital corrections by the on-board gyroscopes (which spun at 10,000 rpm, producing vibrations of 166.67Hz) or thrusters;
• Tidal forces.Any parts ofMirnot at exactly the same distance from Earth tended tofollow separate orbits.As each point was physically part of the station, this was impossible, and so each component was subject to small accelerations from tidal forces;
• The differences in orbital plane between different locations on the station.

Life support

See also:ISS ECLSS

Mir'senvironmental control and life support system(ECLSS) provided or controlledatmospheric pressure,fire detection, oxygen levels, waste management and water supply. The highest priority for the ECLSS was the station's atmosphere, but the system also collected, processed, and stored waste and water produced and used by the crew—a process that recycles fluid from the sink, toilet, and condensation from the air. TheElektronsystem generated oxygenelectrolytically,venting hydrogen to space. Bottled oxygen andsolid fuel oxygen generation(SFOG) canisters, a system known asVika,provided backup. Carbon dioxide was removed from the air by theVozdukhsystem.Other byproducts of human metabolism, such as methane from the intestines and ammonia from sweat, were removed byactivated charcoalfilters. Similar systems are presently used on the ISS.

The atmosphere onMirwas similar toEarth's.Normal air pressure on the station was 101.3kPa(14.7psi); the same as at sea level on Earth.An Earth-like atmosphere offers benefits for crew comfort.

International cooperation

Reinhold Ewald(right) andVasily Tsibliyevin thecore moduleduring Ewald's visit toMir

Scale model replica of the MIR Space Station at the Euro Space Center Belgium

Interkosmos

Main article:Interkosmos

Interkosmos (‹See Tfd›Russian:ИнтерКосмос) was a Soviet Union space exploration programme which allowed members from countries allied with the Soviet Union to participate in crewed and uncrewed space exploration missions. Participation was also made available to governments of countries such as France and India.

Only the last three of the programme's fourteen missions consisted of an expedition toMirbut none resulted in an extended stay in the station:

• Muhammed Faris–EP-1(1987)SyriaTurkey
• Aleksandr Panayatov Aleksandrov–EP-2(1988)Bulgaria
• Abdul Ahad Mohmand–EP-3(1988)Afghanistan

European involvement

See also:Euromir

Various European astronauts visitedMiras part of several cooperative programmes:

• Jean-Loup Chrétien–Aragatz(1988)France
• Helen Sharman–Project Juno(1991)UK
• Franz Viehböck–Austromir '91(1991)Austria
• Klaus-Dietrich Flade–Mir'92(1992)Germany
• Michel Tognini–Antarès(1992)France
• Jean-Pierre Haigneré–Altair(1993)France
• Ulf Merbold–Euromir '94(1994)Germany
• Thomas Reiter–Euromir '95(1995)Germany
• Claudie Haigneré–Cassiopée(1996)France
• Reinhold Ewald–Mir'97(1997)Germany
• Léopold Eyharts–Pégase(1998)France
• Ivan Bella–Stefanik(1999)Slovakia

Shuttle–Mirprogram

Main article:Shuttle–Mir Program

Theseven NASA astronautswho carried out long-duration missions onMir

In the early 1980s, NASA planned to launch a modular space station calledFreedomas a counterpart toMir,while the Soviets were planning to constructMir-2in the 1990s as a replacement for the station.Because of budget and design constraints,Freedomnever progressed past mock-ups and minor component tests and, withthe fall of the Soviet Unionand the end of theSpace Race,the project was nearly cancelled entirely by theUnited States House of Representatives.Thepost-Soviet economic chaosin Russia also led to the cancellation ofMir-2, though only after its base block,DOS-8,had been constructed.Similar budgetary difficulties were faced by other nations with space station projects, which prompted the US government to negotiate with European states, Russia, Japan, and Canada in the early 1990s to begin a collaborative project.In June 1992, American presidentGeorge H. W. Bushand Russian presidentBoris Yeltsinagreed to cooperate onspace exploration.The resultingAgreement between the United States of America and the Russian Federation Concerning Cooperation in the Exploration and Use of Outer Space for Peaceful Purposescalled for a short joint space programme with one Americanastronautdeployed to the Russian space stationMirand two Russiancosmonautsdeployed to a Space Shuttle.

In September 1993, US Vice PresidentAl Gore Jr.,and Russian Prime MinisterViktor Chernomyrdinannounced plans for a new space station, which eventually became theISS.They also agreed, in preparation for this new project, that the United States would be heavily involved in theMirprogramme as part of an international project known as theShuttle–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 theirspace agencies,the USNational Aeronautics and Space Administration(NASA) and theRussian 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.

Other visitors

• Toyohiro Akiyama–Kosmoreporter(1990)Japan
• Chris Hadfield–STS-74(1995)Canada
• A Britishcon artist,Peter Rodney Llewellyn, almost visitedMirin 1999 on a private contract after promisingUS$100 million for the privilege.

Life on board

Time exposure ofMirpassing over Earth's surface, May 1997.

A video tour ofMirfrom September 1996, duringSTS-79

A view of the interior of thecore module's docking node, showing the crowded nature of the station.

Inside, the 130-tonne (140-short-ton)Mirresembled a crampedlabyrinth,crowded with hoses, cables and scientific instruments—as well as articles of everyday life, such as photos, children's drawings, books and a guitar. It commonly housed three crew members, but was capable of supporting as many as six for up to a month. The station was designed to remain in orbit for around five years; it remained in orbit for fifteen.As a result, NASA astronaut John Blaha reported that, with the exception ofPrirodaandSpektr,which were added late in the station's life,Mirdid look used, which is to be expected given it had been lived in for ten to eleven years without being brought home and cleaned.

Crew schedule

The time zone used on boardMirwasMoscow Time(UTC+03). The windows were covered during night hours to give the impression of darkness because the station experienced 16 sunrises and sunsets a day. A typical day for the crew began with a wake-up at 08:00, followed by two hours of personal hygiene and breakfast. Work was conducted from 10:00 until 13:00, followed by an hour of exercise and an hour's lunch break. Three more hours of work and another hour of exercise followed lunch, and the crews began preparing for their evening meal at about 19:00. The cosmonauts were free to do as they wished in the evening, and largely worked to their own pace during the day.

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 aboardMir), or make use of the station's ham radio.Two amateur radio call signs, U1MIR and U2MIR, were assigned toMirin the late 1980s, allowingamateur radio operatorson 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 boardMirwas 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 onMir,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 onMirdid 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.

AstronautShannon Lucid,who set the record for longest stay in space by a woman while aboardMir(surpassed bySunita Williams11 years later on the ISS), also commented about working aboardMirsaying "I think going to work on a daily basis onMiris 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. "

Exercise

Shannon Lucidexercises on a treadmill during her stay aboardMir.

The most significant adverse effects of long-term weightlessness aremuscle atrophyand deterioration of theskeleton,orspaceflight osteopenia.Other significant effects include fluid redistribution, a slowing of thecardiovascular system,decreased production ofred blood cells,balance disorders, and a weakening of theimmune system.Lesser symptoms include loss of body mass, nasal congestion, sleep disturbance, excessflatulence,and puffiness of the face. These effects begin to reverse quickly upon return to the Earth.

To prevent some of these effects, the station was equipped with twotreadmills(in the core module andKvant-2) and astationary bicycle(in the core module); each cosmonaut was to cycle the equivalent of 10 kilometres (6.2 mi) and run the equivalent of 5 kilometres (3.1 mi) 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.

Hygiene

One of thespace toiletsused aboardMir

There were twospace toilets(ASUs) onMir,located in thecore moduleandKvant-2.They used a fan-driven suction system similar to the Space Shuttle Waste Collection System. The user is first fastened to the toilet seat, which was equipped with spring-loaded restraining bars to ensure a good seal. A lever operated a powerful fan and a suction hole slid open: the air stream carried the waste away. Solid waste was collected in individual bags which were stored in an aluminium container. Full containers were transferred to Progress spacecraft for disposal. Liquid waste was evacuated by a hose connected to the front of the toilet, with anatomically appropriate "urine funnel adapters" attached to the tube so both men and women could use the same toilet. Waste was collected and transferred to the Water Recovery System, where it could be recycled back into drinking water, but was usually used to produce oxygen via theElektronsystem.

Mirfeatured a shower, theBania,located inKvant-2. It was an improvement on the units installed in previousSalyutstations, 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 toMir,bacteria and larger organisms were found to have proliferated in water globules formed from moisture that had condensed behind service panels.

Sleeping in space

Main article:Sleep in space

CosmonautYury Usachovin hisKayutka

The station provided two permanent crew quarters, theKayutkas,phonebox-sized booths set towards the rear of the core module, each featuring a tethered sleeping bag, a fold-out desk, a porthole, and storage for personal effects. Visiting crews had no allocated sleep module, instead attaching a sleeping bag to an available space on a wall; US astronauts installed themselves withinSpektruntil a collision with aProgress spacecraftcaused the depressurisation of that module.It was important that crew accommodations be well ventilated; otherwise, astronauts could wake up oxygen-deprived and gasping for air, because a bubble of their own exhaled carbon dioxide had formed around their heads.

Food and drink

See also:Space food

Most of the food eaten by station crews was frozen, refrigerated or canned. Meals were prepared by the cosmonauts, with the help of adietitian,before their flight to the station. The diet was designed to provide around 100 g ofprotein,130 g offatand 330 g ofcarbohydratesper day, in addition to appropriate mineral and vitamin supplements. Meals were spaced out through the day to aid assimilation.Canned food such as jellied beef tongue was placed into a niche in the core module's table, where it could be warmed in 5–10 minutes. Usually, crews drank tea, coffee and fruit juices, but, unlike the ISS, the station also had a supply ofcognacandvodkafor special occasions.

Microbiological environmental hazards

In the 1990s ninety species of micro-organisms were found insideMir,four years after the station's launch. By the time of its decommission in 2001, the number of known different micro-organisms had grown to 140. As space stations get older, the problems with contamination get worse.Molds that develop aboard space stations can produce acids that degrade metal, glass and rubber.The molds inMirwere found growing behind panels and inside air-conditioning equipment. The molds also caused a foul smell, which was often cited as visitors' strongest impression.Researchers in 2018 reported, after detecting the presence on theInternational Space Station(ISS) of fiveEnterobacter bugandensisbacterial strains, none pathogenic to humans, thatmicroorganismson ISS should be carefully monitored to continue ensuring a medically healthy environment for the astronauts.

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.

Station operations

Expeditions

Main article:List of Mir Expeditions

See also:List of Mir spacewalks

Mirwas visited by a total of 28 long-duration or "principal" crews, each of which was given a sequential expedition number formatted as EO-X. Expeditions varied in length (from the 72-day flight of the crew ofEO-28to the 437-day flight ofValeri Polyakov), but generally lasted around six months.Principal expedition crews consisted of two or three crew members, who often launched as part of one expedition but returned with another (Polyakov launched with EO-14 and landed with EO-17).The principal expeditions were often supplemented with visiting crews who remained on the station during the week-long handover period between one crew and the next before returning with the departing crew, the station's life support system being able to support a crew of up to six for short periods.The station was occupied for a total of four distinct periods; 12 March–16 July 1986 (EO-1), 5 February 1987 – 27 April 1989 (EO-2–EO-4), the record-breaking run from 5 September 1989 – 28 August 1999 (EO-5–EO-27), and 4 April–16 June 2000 (EO-28).By the end, it had beenvisited by 104 different people from twelve different nations,making it the most visited spacecraft in history (a record latersurpassed by the ISS).

Early existence

See also:Mir Core ModuleandKvant-1

The core module withKvant-1andSoyuz TM-3

Due to pressure to launch the station on schedule, mission planners were left without Soyuz spacecraft or modules to launch to the station at first. It was decided to launchSoyuz T-15on a dual mission to bothMirandSalyut 7.

Leonid KizimandVladimir Solovyovfirst docked withMiron 15 March 1986. During their nearly 51-day stay onMir,they brought the station online and checked its systems. They unloaded twoProgress spacecraftlaunched after their arrival,Progress 25andProgress 26.

On 5 May 1986, they undocked fromMirfor a day-long journey to Salyut 7. They spent 51 days there and gathered 400 kg of scientific material from Salyut 7 for return toMir.While Soyuz T-15 was at Salyut 7, the uncrewedSoyuz TM-1arrived at the unoccupiedMirand remained for 9 days, testing the newSoyuz TMmodel. Soyuz T-15 redocked withMiron 26 June and delivered the experiments and 20 instruments, including a multichannelspectrometer.The EO-1 crew spent their last 20 days onMirconducting Earth observations before returning to Earth on 16 July 1986, leaving the new station unoccupied.

The second expedition toMir,EO-2,launched onSoyuz TM-2on 5 February 1987. During their stay, theKvant-1module, launched on 30 March 1987, arrived. It was the first experimental version of a planned series of '37K' modules scheduled to be launched toMironBuran.Kvant-1 was originally planned to dock withSalyut 7;due to technical problems during its development, it was reassigned toMir.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 theKvant-1 module withMiron 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 RomanenkoandAleksandr Laveykin,conducted anEVAto 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) andJean-Loup Chrétien(France). With the departure ofEO-4onSoyuz TM-7on 27 April 1989 the station was again left unoccupied.

Third start

See also:Kvant-2andKristall

The launch ofSoyuz TM-8on 5 September 1989 marked the beginning of the longest human presence in space, until 23 October 2010, when this record was surpassed by the ISS.It also marked the beginning ofMir'ssecond expansion. TheKvant-2andKristallmodules were now ready for launch.Alexander ViktorenkoandAleksandr Serebrovdocked withMirand brought the station out of its five-month hibernation. On 29 September the cosmonauts installed equipment in the docking system in preparation for the arrival ofKvant-2, the first of the 20tonneadd-on modules based on theTKS spacecraftfrom theAlmazprogramme.

Mirfollowing the arrival ofKvant-2in 1989

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 bothKvant-2 andMir,the new module was docked manually on 6 December.Kvant-2 added a second set ofcontrol moment gyroscopes(CMGs, or "gyrodynes" ) toMir,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 asIkar), an equivalent of the USManned Maneuvering Unit,was located insideKvant-2's airlock.

Soyuz TM-9launchedEO-6crew membersAnatoly SolovyevandAleksandr Balandinon 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 boardMirsaw the addition of theKristallmodule, launched 31 May 1990. The first docking attempt on 6 June was aborted due to an attitude control thruster failure.Kristallarrived at the front port on 10 June and was relocated to the lateral port oppositeKvant-2 the next day, restoring the equilibrium of the complex. Due to the delay in the docking ofKristall,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.

Kristallcontained 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 twoAndrogynous Peripheral Attach System(APAS-89) docking ports designed to be compatible with theBuranspacecraft. Although they were never used in aBurandocking, they were useful later during the Shuttle-Mirprogramme, providing a berthing location for USSpace Shuttles.

TheEO-7relief crew arrived aboardSoyuz TM-10on 3 August 1990. The new crew arrived atMirwithquailforKvant-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-8andEO-9,continued the work of their predecessors whilst tensions grew back on Earth.

Post-Soviet period

A view ofMirfromSoyuz TM-17on 3 July 1993 showing ongoing docking operations at the station

TheEO-10crew, launched aboardSoyuz TM-13on 2 October 1991, was the last crew to launch from the USSR and continued the occupation ofMirduringthe fall of the Soviet Union.The crew launched as Soviet citizens and returned to Earth on 25 March 1992 as Russians. The newly formedRussian Federal Space Agency(Roscosmos) was unable to finance the unlaunchedSpektrandPrirodamodules, instead putting them into storage and endingMir'ssecond expansion.

The first human mission flown from an independentKazakhstanwasSoyuz TM-14,launched on 17 March 1992, which carried theEO-11crew toMir,docking on 19 March before the departure of Soyuz TM-13. On 17 June, Russian PresidentBoris Yeltsinand US PresidentGeorge H. W. Bushannounced what would later become the Shuttle-Mirprogramme, a cooperative venture which proved useful to the cash-strapped Roskosmos (and led to the eventual completion and launch ofSpektrandPriroda).EO-12followed in July, alongside a brief visit by French astronautMichel Tognini.The following crew,EO-13,began preparations for the Shuttle-Mirprogramme by flying to the station in a modified spacecraft,Soyuz TM-16(launched on 26 January 1993), which was equipped with anAPAS-89docking system rather than the usual probe-and-drogue, enabling it to dock toKristalland 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 calledRezonansconducted 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 onMirexperienced occasional reminders of theeconomic chaosoccurring in Russia. The initial cancellation ofSpektrandPrirodawas the first such sign, followed by the reduction in communications as a result of the fleet oftracking shipsbeing withdrawn from service byUkraine.The new Ukrainian government also vastly raised the price of theKursdocking systems, manufactured inKyiv– the Russians' attempts to reduce their dependence onKurswould 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 theEO-14crew aboardSoyuz TM-17in July; shortly before launch there was a black-out at the pad, and the power supply to the nearby city ofLeninskfailed an hour after launch.Nevertheless, the spacecraft launched on time and arrived at the station two days later. All ofMir'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 whileProgress M-18vacated the core module's front port and departed.

The EO-13 crew departed on 22 July, and soon afterMirpassed through the annualPerseidmeteor 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-18arrived on 10 January 1994 carrying theEO-15crew (includingValeri Polyakov,who was to remain onMirfor 14 months), andSoyuz TM-17left on 14 January. The undocking was unusual in that the spacecraft was to pass alongKristallin 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 ofKristall.

On 3 February 1994,MirveteranSergei Krikalevbecame the first Russian cosmonaut to launch on a US spacecraft, flying onSpace ShuttleDiscoveryduringSTS-60.

The launch ofSoyuz TM-19,carrying theEO-16crew, 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 theEO-17crew arrived inSoyuz TM-20.

Shuttle–Mir

Main article:Shuttle–Mir Program

See also:Spektr,Priroda,andMir Docking Module

Space ShuttleAtlantisdocked toMironSTS-71.

The 3 February launch ofSpace ShuttleDiscovery,flyingSTS-63,opened operations onMirfor 1995. Referred to as the "near-Mir"mission, the mission saw the first rendezvous of a Space Shuttle withMiras the orbiter approached within 37 feet (11 m) of the station as a dress rehearsal for later docking missions and for equipment testing.Five weeks afterDiscovery'sdeparture, theEO-18crew, including the first US cosmonautNorman Thagard,arrived inSoyuz TM-21.The EO-17 crew left a few days later, with Polyakov completing his record-breaking 437-day spaceflight. During EO-18, theSpektrscience module (which served as living and working space for American astronauts) was launched aboard aProton rocketand docked to the station, carrying research equipment from America and other nations. The expedition's crew returned to Earth aboardSpace ShuttleAtlantisfollowing the first Shuttle–Mirdocking mission,STS-71.Atlantis,launched on 27 June 1995, successfully docked withMiron 29 June becoming the first US spacecraft to dock with a Russian spacecraft since theASTPin 1975.The orbiter delivered theEO-19crew and returned the EO-18 crew to Earth.TheEO-20crew were launched on 3 September, followed in November by the arrival of the docking module duringSTS-74.

The two-manEO-21crew was launched on 21 February 1996 aboardSoyuz TM-23and were soon joined by US crew memberShannon Lucid,who was brought to the station byAtlantisduringSTS-76.This mission saw the first joint US spacewalk onMirtake place deploying theMir Environmental Effects Payloadpackage on the docking module.Lucid became the first American to carry out a long-duration mission aboardMirwith her 188-day mission, which set the US single spaceflight record. During Lucid's time aboardMir,Priroda,the station's final module, arrived as did French visitorClaudie Haigneréflying theCassiopéemission. The flight aboardSoyuz TM-24also delivered theEO-22crew ofValery KorzunandAleksandr Kaleri.

Lucid's stay aboardMirended with the flight ofAtlantisonSTS-79,which launched on 16 September. This, the fourth docking, sawJohn Blahatransferring ontoMirto take his place as resident US astronaut. His stay on the station improved operations in several areas, including transfer procedures for a docked space shuttle, "hand-over" procedures for long-duration American crew members and "ham"amateur radiocommunications, and also saw two spacewalks to reconfigure the station's power grid. Blaha spent four months with the EO-22 crew before returning to Earth aboardAtlantisonSTS-81in January 1997, at which point he was replaced byphysicianJerry 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-builtOrlan-Mspacesuit alongside Russian cosmonautVasili Tsibliyev,flyingEO-23.All three crew members of EO-23 performed a "fly-around" inSoyuz TM-25spacecraft.Linenger and his Russian crewmates Vasili Tsibliyev andAleksandr Lazutkinfaced several difficulties during the mission, including the most severe fire aboard an orbiting spacecraft (caused by a malfunctioningVika), failures of various systems, a near collision withProgress M-33during a long-distance TORU test and a total loss of station electrical power. The power failure also caused a loss ofattitude control,which led to an uncontrolled "tumble" through space.

Damaged solar arrays on theMirSpektrmodule following a collision withProgress M-34in September 1997.

Linenger was succeeded byAnglo-AmericanastronautMichael Foale,carried up byAtlantisonSTS-84,alongside Russian mission specialistElena Kondakova.Foale's increment proceeded fairly normally until 25 June when during the second test of theProgressmanual docking system,TORU,Progress M-34collided with solar arrays on theSpektrmodule 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 closingSpektr'shatch, prevented the crews having to abandon the station inSoyuz TM-25.Their efforts stabilised the station's air pressure, whilst the pressure inSpektr,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 ofSpektrand to attempt to locate the leak,EO-24commanderAnatoly Solovyevandflight engineerPavel Vinogradovcarried 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 fromSpektr'ssystems to the rest of the station. Following these first investigations, Foale and Solovyev conducted a 6-hour EVA outsideSpektrto 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 administratorDaniel Goldindecided to continue.The next flight toMir,STS-86,carriedDavid WolfaboardAtlantis.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 inSpektr's hull.Wolf spent 119 days aboardMirwith the EO-24 crew and was replaced duringSTS-89withAndy Thomas,who carried out the last US expedition onMir.TheEO-25crew arrived inSoyuz TM-27in January 1998 before Thomas returned to Earth on the final Shuttle–Mirmission,STS-91.

Final days and deorbit

Main article:Deorbit of Mir

Mirbreaks up in Earth's atmosphere over theSouth Pacificon 23 March 2001.

Following the 8 June 1998 departure ofDiscovery,the EO-25 crew ofBudarinandMusabayevremained onMir,completing materials experiments and compiling a station inventory. On 2 July,Roskosmosdirector Yuri Koptev announced that, due to a lack of funding to keepMiractive, the station would be deorbited in June 1999.TheEO-26crew ofGennady PadalkaandSergei Avdeyevarrived on 15 August inSoyuz TM-28,alongside physicistYuri Baturin,who departed with the EO-25 crew on 25 August inSoyuz TM-27.The crew carried out two spacewalks, one insideSpektrto reseat some power cables and another outside to set up experiments delivered byProgress M-40,which also carried a large amount of propellant to begin alterations toMir's orbit in preparation for the station's decommissioning. 20 November 1998 saw the launch ofZarya,the first module of theISS,but delays to the new station's service moduleZvezdahad led to calls forMirto be kept in orbit past 1999. Roscosmos confirmed that it would not fundMirpast the set deorbit date.

The crew ofEO-27,Viktor AfanasyevandJean-Pierre Haigneré,arrived inSoyuz TM-29on 22 February 1999 alongsideIvan 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 onSofora.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 departedMiron 28 August 1999, ending a run of continuous occupation, which had lasted for eight days short of ten years.The station'scontrol moment gyroscopes(CMGs, or "gyrodynes" ) and main computer were shut down on 7 September, leavingProgress M-42to controlMirand refine the station's orbital decay rate.

Near the end of its life, there were plans for private interests to purchaseMir,possibly for use as the first orbitaltelevision/movie studio.The privately fundedSoyuz TM-30mission by MirCorp, that was launched on 4 April 2000, carried two crew members,Sergei ZalyotinandAleksandr 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 toMir—while Russia was optimistic aboutMir'sfuture, its commitments to the ISS project left no funding to support the aging station.

Mir's deorbit was carried out in three stages. The first stage involved waiting foratmospheric dragtoreduce the station's orbitto an average of 220 kilometres (140 mi). This began with the docking ofProgress M1-5,a modified version of theProgress-Mcarrying 2.5 times more fuel in place of supplies. The second stage was the transfer of the station into a 165 × 220 km (103 × 137 mi) 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 100 km/60 mi AMSL) occurred at 05:44 UTC nearNadi,Fiji.Major destruction of the station began around 05:52 UTC and most of the unburned fragments fell into theSouth Pacific Oceanaround 06:00 UTC.

Visiting spacecraft

Main articles:Soyuz (spacecraft),Progress (spacecraft),andSpace Shuttle

See also:List of human spaceflights to MirandList of uncrewed spaceflights to Mir

Soyuz TM-24docked withMiras seen from theSpace ShuttleAtlantisduringSTS-79

Mirwas primarily supported by the RussianSoyuzandProgress spacecraftand had two ports available for docking them. Initially, the fore and aft ports of the core module could be used for dockings, but following the permanent berthing ofKvant-1 to the aft port in 1987, the rear port of the new module took on this role from the core module's aft port. Each port was equipped with the plumbing required for Progress cargo ferries to replace the station's fluids and also the guidance systems needed to guide the spacecraft for docking. Two such systems were used onMir;the rear ports of both the core module andKvant-1 were equipped with both theIglaandKurssystems, whilst the core module's forward port featured only the newer Kurs.

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 toMir;Soyuz T-15was the only Igla-equippedSoyuz-Tto visit the station, whilst all other flights used the newer, Kurs-equippedSoyuz-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 carriedRadugacapsules, which could return around 150 kg of experimental results to Earth automatically.Mirwas visited by three separate models of Progress; the original7K-TGvariant equipped with Igla (18 flights), theProgress-Mmodel equipped with Kurs (43 flights), and the modifiedProgress-M1version (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 ofProgress M-34,when the long-range use of the system resulted in the spacecraft striking the station, damagingSpektrand causingdecompression).

In addition to the routine Soyuz and Progress flights, it was anticipated thatMirwould also be the destination for flights by the SovietBuranspace shuttle,which was intended to deliver extra modules (based on the same "37K"busasKvant-1) and provide a much improved cargo return service to the station.Kristallcarried twoAndrogynous Peripheral Attach System(APAS-89) docking ports designed to be compatible with the shuttle. One port was to be used forBuran;the other for the plannedPulsarX-2 telescope, also to be delivered byBuran.The cancellation of theBuranprogramme meant these capabilities were not realised until the 1990s when the ports were used instead by USSpace Shuttlesas part of the Shuttle-Mirprogramme (after testing by the specially modifiedSoyuz TM-16in 1993). Initially, visitingSpace Shuttle orbitersdocked directly toKristall,but this required the relocation of the module to ensure sufficient distance between the shuttle andMir's solar arrays.To eliminate the need to move the module and retract solar arrays for clearance issues, aMir Docking Modulewas later added to the end ofKristall.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 toMir,the temporary enlargements of living and working areas amounted to a complex that was the largestspacecraftin history at that time, with a combined mass of 250tonnes(280short tons).

Mission control centre

Main article:RKA Mission Control Center

RKA Mission Control Center(2007)

Mirand its resupply missions were controlled from the Russianmission control centre(‹See Tfd›Russian:Центр управления полётами) inKorolyov,near theRKK Energiaplant. Referred to by its acronym ЦУП ( "TsUP" ), or simply as 'Moscow', the facility could process data from up to ten spacecraft in three separate control rooms, although each control room was dedicated to a single programme; one toMir;one toSoyuz;and one to the Soviet space shuttleBuran(which was later converted for use with the ISS).The facility is now used to control theRussian Orbital Segmentof the ISS.The flight control team were assigned roles similar to the system used by NASA at their mission control centre inHouston,including:

• The Flight Director, who provided policy guidance and communicated with the mission management team;
• The Flight Shift Director, who was responsible for real-time decisions within a set of flight rules;
• The Mission Deputy Shift Manager (MDSM) for the MCC was responsible for the control room's consoles, computers and peripherals;
• The MDSM for Ground Control was responsible for communications;
• The MDSM for Crew Training was similar to NASA's 'capcom,' or capsule communicator; usually someone who had served as theMircrew's lead trainer.

Unused equipment

Three command and control modules were constructed for theMirprogram. One was used in space; one remained in a Moscow warehouse as a source of repair parts if needed,and the third was sold to an educational and entertainment complex in the US in 1997.Tommy Bartlett Exploratorypurchased the unit and had it shipped toWisconsin Dells, Wisconsin,where it became the centrepiece of the complex's Space Exploration wing.

Safety aspects

Ageing systems and atmosphere

In the later years of the programme, particularly during the Shuttle-Mirprogramme,Mirsuffered from various systems failures. It had been designed for five years of use, but eventually flew for fifteen, and in the 1990s was showing its age, with frequent computer crashes, loss of power, uncontrolled tumbles through space and leaking pipes.Jerry Linengerin his book about his time on the facility says that the cooling system had developed tiny leaks too small and numerous to be repaired, that permitted the constant release ofcoolant.He says that it was especially noticeable after he had made a spacewalk and become used to the bottled air in his spacesuit. When he returned to the station and again began breathing the air insideMir,he was shocked by the intensity of the smell and worried about the possible negative health effects of breathing such contaminated air.

Various breakdowns of the Elektron oxygen-generating system were a concern; they led crews to become increasingly reliant on the backupVikasolid-fuel oxygen generator(SFOG) systems, which led to a fire during the handover between EO-22 and EO-23.(see alsoISS ECLSS)

Accidents

A charred panel inKvant-1following theVikafire

Several accidents occurred which threatened the station's safety, such as the glancing collision betweenKristallandSoyuz TM-17during proximity operations in January 1994. The three most alarming incidents occurred duringEO-23.The first was on 23 February 1997 during the handover period fromEO-22to EO-23, when a malfunction occurred in the backupVikasystem, achemical oxygen generatorlater known as solid-fuel oxygen generator (SFOG). TheVikamalfunction led to a fire which burned for around 90 seconds (according to official sources at the TsUP; astronautJerry Linengerinsists the fire burned for around 14 minutes), and produced large amounts of toxic smoke that filled the station for around 45 minutes. This forced the crew to don respirators, but some of the respirator masks initially worn were broken. Some of thefire extinguishersmounted on the walls of the newer modules were immovable.

Picture of the damage caused by the collision withProgress M-34.Picture was taken bySpace ShuttleAtlantisduringSTS 86

The other two accidents concerned testing of the station'sTORUmanual docking system to manually dockProgress M-33andProgress M-34.The tests were to gauge the performance of long-distance docking and the feasibility of removal of the expensiveKursautomatic docking system from Progress spacecraft. Due to malfunctioning equipment, both tests failed, with Progress M-33 narrowly missing the station and Progress M-34 strikingSpektrand puncturing the module, causing the station to depressurise and leading toSpektrbeing permanently sealed off. This in turn led to a power crisis aboardMiras the module's solar arrays produced a large proportion of the station's electrical supply, causing the station to power down and begin to drift, requiring weeks of work to rectify before work could continue as normal.

Radiation and orbital debris

Space debrisinlow Earth orbit

Without the protection of the Earth's atmosphere, cosmonauts were exposed to higher levels ofradiationfrom a steady flux ofcosmic raysand trapped protons from theSouth Atlantic Anomaly.The station's crews were exposed to anabsorbed doseof about 5.2cGyover the course of theMir EO-18expedition, producing anequivalent doseof 14.75cSv,or 1133 μSv per day.This daily dose is approximately that received from naturalbackground radiationon Earth in two years.The radiation environment of the station was not uniform; closer proximity to the station's hull led to an increased radiation dose, and the strength of radiation shielding varied between modules;Kvant-2's being better than the core module, for instance.

The increased radiation levels pose a higher risk of crews developing cancer, and can cause damage to thechromosomesoflymphocytes.These cells are central to theimmune systemand so any damage to them could contribute to the loweredimmunityexperienced 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 ofcataractsin 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 whichMirorbited there is a variety ofspace debris,consisting of everything from entire spentrocket stagesand defunctsatellites,to explosion fragments, paint flakes, slag from solid rocket motors,coolant released byRORSATnuclear powered satellites,small needles,and many other objects. These objects, in addition to naturalmicrometeoroids,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 tospacewalkingcosmonauts, as such objects couldpuncture their spacesuits,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 shouldMirbe damaged.

See also

• Skylab,a defunct predecessor space station
• Out of the Present,1995 documentary
• Orphans of Apollo,a 2008 documentary film which describes how a band of entrepreneurs tried to privatize the space stationMirand the resulting story of MirCorp.

External links

• NASA animation ofMir's deorbit
• MirDiaryArchived16 November 2020 at theWayback Machine
• Diagrams, pictures and background info
• Information on problems aboard Mir
• Shuttle-Mir:Phase 1 Program Joint Report
• Mir Space Station (NASA)
• "35 Years Ago: Launch of Mir Space Station's First Module".NASA. 22 February 2021.