Salyut - astronomy.

Salyut - astronomy. I INTRODUCTION Salyut, series of space stations designed by the Union of Soviet Socialist Republics (USSR) to provide a safe space environment in which crew members could live and work on scientific and military projects. Salyut space stations were launched unpiloted--their crews of two or three cosmonauts flew to the stations in Soyuz spacecraft, which remained docked at the stations as long as the cosmonauts were there. Between 1971 and 1982 the USSR launched nine Salyut space stations, six of which made it successfully into orbit. Four of the successful Salyut space stations had mainly civilian objectives; the others were designed for military activity. The Salyut space stations became laboratories for learning to live and work in space. Soviet cosmonauts (see Astronaut) lived on the Salyut space stations for up to 237 days to study the human body's reaction to prolonged weightlessness. They also observed the Earth, Sun, and stars; performed biology experiments; manufactured new metals in furnaces in the absence of gravity; and tested equipment for future stations. The experiences provided by the Salyut program helped the USSR prepare for the space station Mir. II SPACECRAFT AND SUPPORTING SYSTEMS Salyut stations were launched on top of large Proton rockets. Although both military and civilian versions of Salyut had a large rear compartment attached to a mediumsized forward compartment, their designs were otherwise different. On military stations, the docking port, a hatch designed to lock with other spacecraft, was located at the back of the station on a spherical airlock compartment attached to the rear compartment. The civilian Salyut docking port was on a small cylindrical airlock compartment at the front of the station. The last two Salyut spacecraft had two docking ports, one at each end. Both military and civilian types weighed about 19,000 kg (about 40,000 lb). They measured 4.15 m (about 15 ft) at their widest point and were about 15 m (45 ft) long. The military stations carried a small unpiloted film return capsule, which brought exposed film from the station's telescopic spy camera back to the USSR. All Salyut stations were equipped with solar panels, which turned sunlight into electricity. The military Salyut space stations had two large panels. The first civilian station had four small panels, and later civilian stations had three large panels. Early Salyut space stations had only one docking port, so they could not be resupplied because the single port was needed for docking with Soyuz spacecraft. The manned Soyuz missions could not carry the massive amounts of air, food, and water to keep the station running indefinitely. Later Salyut stations had docking ports at both ends, permitting docking with Soyuz spacecraft at the front port and with unpiloted delivery vehicles, called Progress freighters, at the rear port. These freighters delivered food, water, air, fuel, repair parts, and scientific equipment, which allowed Salyut stations to remain in orbit for years. A second Soyuz could dock at the rear port if it was not occupied by a Progress freighter, so long-duration crews could have visitors. The second port also enabled dockings by space station module test vehicles to provide cosmonauts with added workspace and equipment, a system that would become crucial to the space station Mir. III MISSION HIGHLIGHTS Salyut 1 was launched on April 19, 1971. The Soyuz 10 crew launched April 23, 1971, docked with Salyut 1, but could not enter the station. Soyuz 11 docked successfully with Salyut 1 on June 7, 1971. Cosmonauts Georgi Dobrovolski, Viktor Patsayev, and Vladislav Volkov lived on board the station for three weeks, establishing a new space-endurance record. They completed many science experiments in space, including a study of how plants grow in space. But during return to Earth on June 29, 1971, the air escaped from Soyuz 11, killing the cosmonauts, who wore no spacesuits. On October 11, 1971, the USSR sent a radio command to Salyut 1 to make it fall out of orbit into Earth's atmosphere. This became standard procedure for Salyut stations when their usefulness ended. Any parts that did not burn up through atmospheric friction fell into the Pacific Ocean. The Soviets then lost three stations in a row, although fortunately with no more loss of life. An unnamed civilian Salyut fell to Earth minutes after launch on July 29, 1972, after its launching Proton rocket failed. The first military station, Salyut 2, was launched on April 3, 1973, and broke apart in orbit on April 25, 1973. The third civilian station, called Cosmos 557, reached orbit on May 11, 1973, but reentered the atmosphere prematurely on May 22, 1973. The Salyut 3 military station launched on June 24, 1974. The Soyuz 14 crew docked on July 4, 1974, and worked on board for two weeks. After launch on August 26, 1974, the Soyuz 15 cosmonauts failed to dock because their spacecraft developed a malfunction in its docking system. The station's film return capsule was launched automatically from the station and landed in the USSR on September 23, 1974. Salyut 3 reentered the atmosphere on January 24, 1975. Civilian Salyut 4, launched December 26, 1974, received Soyuz 17 and 18 and the unmanned Soyuz 20 spacecraft. The Soyuz 18 crew of Pyotr Klimuk and Vitali Sevastyanov spent two months in orbit, performing experiments with insects and studying astronomical bodies from space. Salyut 4 reentered the atmosphere on February 2, 1976. Salyut 5, the last military space station, was launched on June 22, 1976, and received the Soyuz 21 and 24 crews. The Soyuz 21 crew stayed on board Salyut 5 for almost two months, but Soyuz 23 could not dock due to another malfunction. Soyuz 24's crew loaded the film return capsule, which landed on February 26, 1977. Salyut 5 reentered the atmosphere on August 8, 1977. Salyut 6 was the first Salyut space station to have docking ports at both ends, allowing it to be resupplied. This station was launched on September 29, 1977, signaling a new era in space-station activity. The Soyuz 26 crew of Yuri Romanenko and Georgi Grechko lived 96 days on the station, breaking the 84-day space endurance record set by the third United States Skylab crew in 1974. Guest cosmonauts from Czechoslovakia, Hungary, Mongolia, Romania, Cuba, Vietnam, and East Germany visited Salyut 6. In 1980 Leonid Popov and Valeri Ryumin lived on the station for 185 days. In all, 16 cosmonaut crews and 12 Progress freighters visited Salyut 6. After the station's last crew left in 1981, a large unpiloted transport spacecraft called Cosmos 1267 docked at the front port. The USSR had originally built this type of vehicle to carry cosmonauts to the military Salyut space stations. After the last military Salyut reentered the atmosphere, Cosmos 1267-type spacecraft served the civilian program as freighters and space station module test vehicles. A nudge from Cosmos 1267's engines sent Salyut 6 into the Earth's atmosphere on July 29, 1982. Salyut 7, the last Salyut, was launched on April 19, 1982. Although this station was almost identical to Salyut 6, it was plagued by problems. Its propulsion system failed in 1983, and an electrical system failure in 1985 nearly destroyed the station. The USSR turned these problems to its advantage, however, gaining valuable experience in repairs and spacewalks. In 1983, Cosmos 1443, which resembled Cosmos 1267, remained docked to Salyut 7 for two months. Cosmonauts Leonid Kizim, Vladimir Solovyov, and Oleg Atkov set a new endurance record of 237 days in orbit in 1984. Cosmos 1686, the first true space-station module, docked automatically with Salyut 7 in 1985. Most of the modules attached to the Mir space station resembled Cosmos 1686. All together, ten crews visited Salyut 7; the last arrived in March 1986 when the first crew of the Mir space station visited Salyut 7 on a spacewalk to salvage equipment and experiments. Salyut 7 was also visited by 13 Progress freighters bringing supplies. Salyut 7 with the docked Cosmos 1686 reentered Earth's atmosphere out of control in 1991, raining wreckage on Argentina and ending the Salyut program. Contributed By: David S. F. Portree Microsoft ® Encarta ® 2009. © 1993-2008 Microsoft Corporation. All rights reserved.