Space Station Mir

''Mir'' (russian: Мир, ; ) was a space station that operated in low Earth orbit from 1986 to 2001, operated by the Soviet Union and later by 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 orbit decayed. The station served as a microgravity research laboratory in which crews conducted experiments in biology, human biology, physics, astronomy, meteorology, and spacecraft systems with a goal of developing technologies required for permanent occupation of 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 rockets 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 and 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'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 Intercosmos, 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).

Origins

''Mir'' was authorised by a 17 February 1976 decree, to design an improved model of the Salyut DOS-17K space stations. Four Salyut space stations had been launched since 1971, with three more being launched during ''Mirs development. It was planned that the station's core module ( DOS-7 and the backup DOS-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 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 rocket 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 Cosmonaut's 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.

Station structure

Assembly

The orbital assembly of ''Mir'' began on 19 February 1986 with the launch of the ''Proton-K'' rocket. Four of the six modules which were later added ( ''Kvant''-2 in 1989, ''Kristall'' in 1990, ''Spektr'' in 1995 and ''Priroda'' in 1996) followed the same sequence to be added to the main ''Mir'' complex. 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 its Lyappa arm to 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 two ''Konus'' drogues, 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''-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.

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 either Proton-K rockets or .

Unpressurised elements

In addition to the pressurised modules, ''Mir'' featured several external components. The largest component was the ''Sofora'' girder, a large scaffolding-like structure consisting of 20 segments which, when assembled, projected 14 metres from its mount on ''Kvant''-1. A self-contained thruster block, the VDU (Vynosnaya Dvigatyelnaya Ustanovka), was mounted on the end of ''Sofora'' and was used to augment the roll-control thrusters on the core module. The VDU's increased distance from ''Mirs 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 of ''Sofora'' on ''Kvant''-1. This girder, a small prototype of a structure intended to be used on ''Mir''-2 to 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 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.

Power supply

Photovoltaic (PV) arrays powered ''Mir''. The station used a 28 volt DC supply which provided 5-, 10-, 20- and 50-amp

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