Wednesday, July 4, 2007

Mir space station

Mir (Russian for “peace”) was conceived in 1976 as the climax of the (then) Soviet program to achieve the long-duration presence of a man in space. Its first component was launched into orbit ten years later. The first modular station assembled in space, it is the pioneer work of extraterrestrial building; constructed in a virtually gravity-free environment, it is unique among architectural and engineering works. Earlier space stations had been integral units, completed before launching. Mir circled the earth for over fifteen years. As first proposed, it was 43 feet (13.1 meters) long and 13.6 feet (4.2 meters) in diameter; its mass was 46,200 pounds (20,900 kilograms). By 1985 the Russian Space Agency had decided that four to six additional modules, each with a mass of 46,000 pounds (20,800 kilograms), would be moored at docking ports on the station. By the time the final module was in place, the total mass was about 221,000 pounds (100,000 kilograms). Mir, humanity’s first landmark—if that is the correct word—in space, orbited the earth at an altitude of 225 miles (390 kilometers) and an inclination of 51.6 degrees.

The primary function of the station was as a location for scientific experiments, especially in the areas of astrophysics, biology, biotechnology, medicine, and space technology. At various times, Mir was “leased” as a laboratory. Cosmonauts, astronauts, and scientists of many nationalities—Russian, American, Afghan, British, Canadian, German, Japanese, and Syrian among them—conducted over 20,000 experimental programs on board. However, space-watcher David Harland observed that Mir was the first station

to be permanently manned, extending the time spent in space for periods between one month and six; “learning how the technology degrades, and how to repair it, and do so in space” showed its real mission as a technology demonstrator.

The Mir module, the core of the station, was launched on 20 February 1986. Most of it was occupied by the main habitable section—crews’ quarters, a galley, a “bathroom” with shower, hand basin, and toilet—and the operational section, forward of which were the primary docking module and air lock. The galley was furnished with a folding table with built-in food heaters and refuse storage. For privacy, each crew member had a separate cubicle containing a folding chair, sleeping bag, mirror, and porthole. To provide a familiar environment in microgravity, the living quarters had identifiable surfaces: the floor, above several storage compartments, was carpeted in dark green; the light green walls had handrails and devices for securing articles; and the white ceiling had fluorescent lights. The other part of the core module was the station’s control area, set up for flight control, as well as systems and medical monitoring. There were six docking ports on the core’s transfer compartment for secondary modules or the Soyuz and Progress-M transport vehicles: one on the long axis, four along the radius, and another aft, connected to the working module by a 6-foot-diameter (1.8-meter) pressurized tunnel. The engine and fuel tanks were in the assembly compartment.

Five more modules, added between 1987 and 1996, completed the space station. The first, located on the aft docking port, was the astrophysics module known as Kvant-1. Nineteen feet (5.8 meters) long and 14 feet (4.3 meters) in diameter, it contained a pressurized laboratory compartment and a store. Kvant-2, about twice as long as Kvant-1, was the scientific and air-lock module added in 1989 that allowed cosmonauts to work outside the station. It also included a life-support system and water supply. Kristall, a 39-foot-long (12-meter) technological module, was attached to the station in 1990; it carried two solar arrays as well as electrical energy supply, environmental control, motion control, and thermal control systems. In 1995 U.S. astronauts installed a special docking port that allowed the U.S. space shuttle to dock without obstructing the solar arrays. Also in 1995, the Spektr remote-sensing payload arrived at Mir with equipment for surface studies and atmospheric research and four more solar arrays. Mir was completed when the Priroda remote-sensing module arrived on 26 April 1996.

The station could not remain in orbit indefinitely, and two options for closure were available. Mir could be fitted with booster rockets and moved to a higher orbit or simply abandoned and allowed to crash into the ocean. Mir fell into an uninhabited part of the South Pacific late in March 2001. That course of action was chosen so that efforts could be refocused on the construction of the International Space Station (ISS). The decision fits in with the claim of NASA (the National Aeronautics and Space Administration) that the nine U.S. collaborations with Mir since 1994 formed Phase One of the joint construction and operation of the ISS.

The ISS is a joint venture of the United States, Russia, Belgium, Britain, Canada, Denmark, France, Germany, Italy, Japan, the Netherlands, Norway, Spain, Sweden, Switzerland, and Brazil. The first components of the station, the Zarya and Unity modules, were put into Earth orbit in November and December 1998, respectively. Scheduled for completion in 2004 after a total of 44 launches deliver over 100 components, the ISS will have a mass of 1 million pounds (454,500 kilograms) and measure 356 by 290 by 143 feet (109 by 88 by 44 meters). It will orbit Earth at about the same altitude and inclination as its predecessor. A crew of up to seven will have pressurized living and working space about twice as big as the passenger cabin of a jumbo jet. Mir was there first.

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