Space Station

space station or space platform, artificial earth satellite, usually manned, that is placed in a fixed orbit and can serve as a base for astronomical observations; zero-gravity materials processing; satellite assembly, refueling, and repair; or, possibly, as weapons platforms. The first space station was the Soviet Salyut 1, launched in Apr., 1971. The Soyuz 10 spacecraft docked with this station, but the crew did not enter it; two months later the cosmonauts aboard the Soyuz 11 spacecraft docked and entered Salyut 1, remaining aboard for 22 days. By 1982 five more Salyut space stations had been orbited successfully, two of them for military purposes. By rotating the crews regularly, the Soviets were able to staff the stations for extended periods. All the Salyut space stations have decayed and are no longer in orbit.

During this period the United States launched its only true space station. Called Skylab, it was placed in orbit in May, 1973. Skylab housed three three-person crews, the last remaining aboard for 84 days, which at that time was a record for continuous residency in space. Among the tasks accomplished by the Skylab astronauts were biomedical studies to evaluate the effects of weightlessness, photographing the earth to monitor volcanoes and earthquake faults, astronomical observations of optical sources (including extensive studies of Comet Kohoutek), and materials-processing activities such as brazing and welding (to see how they were affected by the lack of gravity). Skylab fell to earth in July, 1974, showering debris over uninhabited parts of Australia and the Indian Ocean.

The Soviet Union launched the core module of the Mir space station in Feb., 1986. It was enlarged several times so that it could accommodate a crew of up to six cosmonauts. The Mir program was enhanced by having international teams conduct experiments at the station; Afghanistan, Bulgaria, France, Germany, Great Britain, India, Japan, Syria and the United States, in addition to Russia and other nations that were formerly part of the Soviet Union, participated. In 1995, Mir cosmonaut Valery Polyakov set an endurance record of nearly 439 days in space, eclipsing the previous record of 326 days set in 1987 by Yuri Romanenko (also while on Mir). In Aug., 1999, its extended 13-year mission concluded, Mir was abandoned. During its lifetime, it orbited the earth 86,331 times and was home to 104 people, including 42 Russian cosmonauts and 7 American astronauts. In Mar., 2001, Mir fell to earth, the largest spacecraft (143 tons/130 metric tons) ever to decay, showering an estimated 1,500 fragments of 44 lb (20 kg) or more over an uninhabited area 120 mi (193 km) wide by 3,600 mi (5795 km) long in the South Pacific.

The United States, Japan, Canada, Brazil, Russia, and 11 members of the European Space Agency (ESA)—Belgium, Denmark, France, Germany, Italy, the Netherlands, Norway, Spain, Sweden, Switzerland, and the United Kingdom—are developing a space station that is being assembled in space. Each partner will contribute a portion of the complex, called the International Space Station (ISS). For example, of the six laboratories that will be included, three will be provided by Russia, one by the United States, one by Japan, and one by ESA. The first element, Zarya (the control module), was orbited by a Russian Proton rocket in Nov., 1998. A month later the U.S. space shuttle Endeavour initiated the first assembly sequence of the ISS, linking the Unity module, a passageway that will connect living and work areas of the station, to Zarya. In July, 2000, the Russian-built Zvezda service module was mated with the two existing components. The first permanent crew—two Russian cosmonauts and an American astronaut—began living aboard the ISS in Nov., 2000, marking the beginning of what is anticipated to be a continuous human presence. When planned construction is completed, the ISS will be 290 ft (88.5 m) long, have a wingspan of 396 ft (120.7 m), and be 143 ft (43.5 m) tall. Its mass will be nearly a million pounds (454,000 kg), and it will support a crew of seven. The plan involves more than 40 space flights over five years, and at least three space vehicles (the space shuttle, the Russian Soyuz rocket, and the Russian Proton rocket) will deliver the various ISS components to earth orbit. Assembly of the more than 100 components will require a combination of human spacewalks and robot technologies. In preparation for the project, construction tasks were practiced by both Mir and shuttle crews, and during 1995–98 nine dockings of the shuttle with Mir were accomplished.

Bibliography

See P. Bizony, Island in the Sky: The ISS (1996); D. M. Harland, The Mir Space Station: Precursor to Space Colonization (1997); M. D. Cole, International Space Station: A Space Mission (1999).

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space station

Soviet/Russian space station Mir, after completion in 1996. The date shown for each module is its …

(credit: Encyclopædia Britannica, Inc.)

Manned artificial structure designed to revolve in a fixed orbit as a long-term base for astronomical observations, study of Earth's resources and environment, military reconnaissance, and investigations of materials and biological systems in weightless conditions. As of 2001, nine space stations have been placed in a low Earth orbit and occupied for varying lengths of time. The Soviet Union orbited the world's first space station, Salyut 1, designed for scientific studies, in 1971. From 1974 to 1982 five more Salyut stations—two outfitted for military reconnaissance—were successfully placed in orbit and occupied. In 1986 the U.S.S.R. launched the core module of Mir, a scientific station that was expanded with five additional modules over the next decade. The U.S. orbited its first space station in 1973; called Skylab, it was equipped as a solar observatory and medical laboratory. In 1998 the U.S. and Russia began the in-orbit construction of the International Space Station (ISS), a complex of laboratory and habitat modules that would ultimately involve contributions from at least 16 countries. In 2000 the ISS received its first resident crew.

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space station [′spās ‚stā·shən]

(aerospace engineering)

An autonomous, permanent facility in space for the conduct of scientific and technological research, earth-oriented applications, and astronomical observations.

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Space Station 

a heavy artificial satellite that functions for a long time in earth, lunar, or planetary orbits. A space station may have a crew of astronauts or may operate automatically.

The function of a space station is to carry out a number of scientific and practical tasks—the study of near-earth space and the earth from the orbit of an artificial earth satellite; the conduct of meteorological, astronomical, radioastronomical, and other observations; the study of problems of navigation; the conduct of biomedical experiments; and the study of behavior of materials and equipment under conditions of space flight. Space stations may also be bases for orbital assembly of heavy spacecraft designed for flight to other planets in the solar system.

The possibility and advisability of creating space stations were scientifically substantiated in the early 20th century in the works of K. E. Tsiolkovskii and Iu. V. Kondratiuk (Russia), H. Oberth (Germany), and Guido von Pirquet and Hermann Noordung (Austria). The creation of space stations and the support of their prolonged functioning in orbit entailed the solution of a number of complex scientific, engineering, and biomedical problems. One of the most important problems is the docking of the spacecraft in orbit. The first manual docking was carried out on Mar. 16, 1966, by the crew of the manned American Gemini 8 spacecraft with an Agena rocket. Automatic docking without direct participation of astronauts was first accomplished on Oct. 30, 1967, in an earth orbit by the Soviet Cosmos 186 and Cosmos 188 artificial earth satellites. The experiment was repeated on Apr. 15, 1968, during the flight of the unmanned Cosmos 212 and Cosmos 213 earth satellites. The first experimental space station was formed and functioned briefly in an earth orbit on Jan. 16, 1969, after the automatic rendezvous and manual docking of manned Soyuz spaceships. By 1971, subsequent launches of Soyuz spaceships had made possible solution of the fundamental problems connected with setting up long-term space stations (Salyut). By 1973 a similar problem had been solved in the USA (Skylab).

The period of active operation in orbit, the crew size, orbital parameters, and the weight and dimensions of a space station depend on its function. The design of a space station is determined primarily by the assembly methods. There are two possible methods. In the first, the station is completely assembled on earth and, ready to carry out assignments, is placed in satellite orbit by a booster rocket. The weight and volume of the station are limited by the thrust of the booster rocket, and therefore the method is suitable for the assembly of stations up to a few dozen tons, such as Salyut and Skylab. In the second method, assembly is accomplished in earth orbit from several independent modules, sections, elements, or spacecraft that are placed in orbit by several boosters. After final assembly and testing in orbit, the station is ready to carry out the entire range of assigned missions. This method makes it possible to set up stations of any required weight and volume, with various dimensions, by using existing booster rockets to place the components in orbit. This is particularly important in sending space stations to the moon and other planets in the solar system. In this case an aborted launch of one of the modules does not cause failure of the program for establishing the station. In both cases the crew can be orbited on board the station (or an element thereof) or can be delivered to the station by transport vehicles, which are launched from earth space centers as necessary and rendezvous and dock with the station.

The flight of a manned space station requires solution of the problems of overcoming the prolonged effect of weightlessness on the human organism, protection from radiation and mi-crometeorites, and provision of reliability and adequate service life of on-board systems and equipment.

The time spent by astronauts in a space station with changing crews is a few weeks or months—for example, the third Skylab crew remained in orbit 84 days. The conditions necessary for normal vital activity and for the conduct of a number of scientific experiments, including biomedical experiments that make it possible to investigate human adaptability to the conditions of weightlessness, are created on board the station. An exercise bicycle, a treadmill, and weighted clothing are used for this purpose. On longer flights, the problem can be solved by other methods. For example, artificial partial gravity may be created by rotating the station or elements of it with respect to the center of gravity.

The provision of protection for the crew against cosmic radiation acquires great importance, especially on long flights. The methods used include both passive protection, which is provided by shielding the station compartments with materials capable of absorbing charged particles that are dangerous to the organism, and active shielding, which is based on the possibility of changing the direction of the flux of charged particles by means of electrostatic or electromagnetic fields.

Meteor protection (with respect to space stations in earth orbit) is provided by outer shields; materials with good anti-impact properties, such as titanium, magnesium, and beryllium, are used for the skin, which is of the honeycomb type, with gaps between the layers. The use of self-sealing materials to cover the body is promising.

The solution of problems associated with the provision of reliability and service life of on-board systems and equipment, especially for prolonged active existence of the space station, begins on earth under conditions as close as possible to those of space flight. All systems and equipment undergo prolonged and thorough testing on the ground.

With the expansion of the frontiers of space, the sphere of activity of space stations is changing qualitatively. For example, the creation of lunar space stations (proposed by Iu. V. Kondratiuk) with a virtually unlimited stay in orbit, which would perform the role of supply bases, will facilitate flights to other planets in the solar system.

REFERENCES

Tsiolkovskii, K. E. Sobr. soch., vols. 1–4. Moscow, 1951–64.
Kondratiuk, Iu. V. Zavoevanie mezhplanetnykh prostranstv, 2nd ed. Moscow, 1947.
Ot kosmicheskikh korablei k orbital’nym stantsiiam, 2nd ed. Moscow, 1971.
“Saliut” na orbite. Moscow, 1973.
Ordway, F. I. “Istoriia, evoliutsiia i dostoinstva proektov orbital’nykh stantsii, vydvigavshikhsia v SShA i Zapadnoi Evrope” In the collection Iz istorii aviatsii i kosmonavtiki, nos. 17–18. Moscow, 1972.

G. A. NAZAROV