Celebrating 50 years of Manned Spaceflight - Part 4: SPACE STATIONS

Space stations have been envisaged since at least 1869 when Everett Hale wrote about a 'brick moon'. Konstantin Tsiolkovsky and Hermann Oberth also published articles about manned spaceflight and space stations. In 1951, Wernher von Braun published his design for a wheeled space station. Salyut and Skylab (1971-1986)

The first space station was Salyut 1, launched by the Soviet Union April 19, 1971. Like all the early space stations, it was "monolithic", intended to be constructed and launched in one piece, and then manned by a crew later. As such, monolithic stations generally contained all their supplies and experimental equipment when launched, and were considered "expended", and then abandoned, when these were used up. Salyut 6 and Salyut 7 were built with two docking ports, which allowed a crew to man the station continually through crew exchange during visits of Soyuz spaceraft. Similarly, the Progess cargo vehicle (a Soyuz derivative) assured a constant supply of consumable materials from Earth. The first Progress mission to Salyut 6 was launched on January 20, 1978. On concluding its mission, Progress would be directed into the atmosphere to burn up. In the following years, Soviet cosmonauts repeatedly broke American and their own records for long-duration missions and ultimately established an almost continuous presence in space. A total 43 Progresses were launched towards Salyut 6 and Salyut 7, and all successfully completed their missions. Skylab was the United States' first space station. It was visited by crews three times between 1973 and 1974 and reentered the Earth's atmosphere and disintegrated in 1979. Mir (1986-1998) Unlike previous stations, the Soviet space station Mir had a modular design. A core unit was launched, and additional modules, generally with a specific role, were added later. This method allows for greater flexibility in operation, as well as removing the need for a single immensely powerful launch vehicle. Modular stations are also designed from the outset to have their supplies provided by logistical support, which allows for a longer lifetime at the cost of requiring regular support launches. It took ten years to build the MIR space station. Counting the Progress M1-5 supply vehicles, a total 110 spacecraft were launched toward Mir during its 15-year history, including additional modules, manned Soyuz transport missions and the US Space Shuttle. They conducted 121 dockings with the station. On March 23, 2001, Mir ended its record-breaking mission with a flawless reentry into the Earth’s atmosphere. ISS (1998-present) The core module of the International Space Station was launched in 1998 and additional modules were brought to the station by the Space Shuttle. On November 2, 2000, the first crew, Bill Shepherd, Yuri Gidzenko and Sergei Krikalev, arrived on board and the station has been manned continuously ever since; NASA recently celebrated the 10th anniversary of ISS habitation. ISS is a remarkable achievement of the five participating space agencies of the United States, Russia, Europe, Japan, and Canada. Fourth generation Soyuz TM-series spacecraft have been providing crew transportation to the ISS for several years and will continue to do so after the Space Shuttle retires. Unmanned Progress-M spacecraft attached to the Zvezda module periodically provide ISS attitude and orbit control, as well as carry cargo. Orbit control includes reboosting manoeuvres, which are required to maintain ISS orbital altitude, and space debris avoidance manoeuvres. In the near future, Europe’s Automated Transfer Vehicle will be used to ferry crews and cargo to the ISS. ATV is a complex spacecraft with a high level of autonomy, including navigation and rendezvous, and will also providing ISS attitude and orbit control.