Early concepts The first mention of anything resembling a space station occurred in
Edward Everett Hale's 1868 "
The Brick Moon". The first to give serious, scientifically grounded consideration to space stations were
Konstantin Tsiolkovsky and
Hermann Oberth about two decades apart in the early 20th century. , in
Hermann Noordung's
The Problem of Space Travel (1929).(Legend:
Achs-Körper:
axle body.
Aufzugschacht:
elevator shaft.
Treppenschacht:
stairwell.
Verdampfungsrohr: boiler pipe). In 1929,
Herman Potočnik's
The Problem of Space Travel was published, the first to envision a "rotating wheel" space station to create
artificial gravity. In 1951,
Wernher von Braun published a concept for a
rotating wheel space station in ''
Collier's Weekly'', referencing Potočnik's idea. However, development of a rotating station was never begun in the 20th century. The
Apollo program had in
its early planning instead of a
lunar landing a crewed
lunar orbital flight and an orbital laboratory station in orbit of Earth, at times called
Project Olympus, as two different possible program goals, until the
Kennedy administration sped ahead and made the Apollo program focus on what was originally planned to come after it, the lunar landing. The Project Olympus space station, or orbiting laboratory of the Apollo program, was proposed as an in-space unfolded structure with the
Apollo command and service module docking. While never realized, the Apollo command and service module would perform
docking maneuvers and eventually become a lunar orbiting module which was used for station-like purposes. But before that the
Gemini program paved the way and achieved the first
space rendezvous (undocked) with
Gemini 6 and
Gemini 7 in 1965. Subsequently in 1966
Neil Armstrong performed on
Gemini 8 the first ever space docking, while in 1967
Kosmos 186 and Kosmos 188 were the first spacecrafts that docked automatically. In January 1969,
Soyuz 4 and
Soyuz 5 performed the first docked, but not internal, crew transfer, and in March,
Apollo 9 performed the first ever internal transfer of astronauts between two docked spaceships.
Salyut, Almaz and Skylab (1973–1974), the first U.S. space station and second overall|255x255px In 1971, the
Soviet Union developed and launched the world's first space station,
Salyut 1. The
Almaz and
Salyut series were eventually joined by
Skylab,
Mir, and
Tiangong-1 and
Tiangong-2. The hardware developed during the initial Soviet efforts remains in use, with evolved variants comprising a considerable part of the ISS, orbiting today. Each crew member stays aboard the station for weeks or months but rarely more than a year. Early stations were monolithic designs that were constructed and launched in one piece, generally containing all their supplies and experimental equipment. A crew would then be launched to join the station and perform research. After the supplies had been consumed, the station was abandoned. The civilian stations
Salyut 6 and
Salyut 7 were built with two docking ports, which allowed a second crew to visit, bringing a new spacecraft with them; the
Soyuz ferry could spend 90 days in space, at which point it needed to be replaced by a fresh Soyuz spacecraft. This allowed for a crew to man the station continually. The American
Skylab (1973–1979) was also equipped with two docking ports, like second-generation stations, but the extra port was never used. The presence of a second port on the new stations allowed
Progress supply vehicles to be docked to the station, meaning that fresh supplies could be brought to aid long-duration missions. This concept was expanded on Salyut 7, which "hard docked" with a
TKS tug shortly before it was abandoned; this served as a proof of concept for the use of modular space stations. The later Salyuts may reasonably be seen as a transition between the two groups.
International Space Station in 2021 The ISS is divided into two main sections, the
Russian Orbital Segment (ROS) and the
US Orbital Segment (USOS). The first module of the ISS,
Zarya, was launched in 1998. The Russian Orbital Segment's "second-generation" modules were able to launch on
Proton, fly to the correct orbit, and dock themselves without human intervention. Connections are automatically made for power, data, gases, and propellants. The Russian autonomous approach allows the assembly of space stations prior to the launch of crew. The Russian "second-generation" modules are able to be reconfigured to suit changing needs. As of 2009,
RKK Energia was considering the removal and reuse of some modules of the ROS on the
Orbital Piloted Assembly and Experiment Complex after the end of mission is reached for the ISS. However, in September 2017, the head of Roscosmos said that the technical feasibility of separating the station to form OPSEK had been studied, and there were now no plans to separate the Russian segment from the ISS. In contrast, the main US modules launched on the
Space Shuttle and were attached to the ISS by crews during
EVAs. Connections for electrical power, data, propulsion, and cooling fluids are also made at this time, resulting in an integrated block of modules that is not designed for disassembly and must be deorbited as one mass.
Axiom Station is a planned commercial space station that will begin as a single module docked to the ISS.
Axiom Space gained NASA approval for the venture in January 2020. The first module, the Payload Power Transfer Module (PPTM), is expected to be launched to the ISS no earlier than 2027. PPTM will remain at the ISS until the launch of Axiom's Habitat One (Hab-1) module about one year later, after which it will detach from the ISS to join with Hab-1. The uncrewed
Shenzhou 8 then successfully performed an automatic rendezvous and docking in November 2011. The crewed
Shenzhou 9 then docked with Tiangong-1 in June 2012, followed by the crewed
Shenzhou 10 in 2013. According to the
China Manned Space Engineering Office, Tiangong-1
reentered over the South
Pacific Ocean, northwest of
Tahiti, on 2 April 2018 at 00:15 UTC. A second space laboratory
Tiangong-2 was launched in September 2016, while a plan for
Tiangong-3 was merged with Tiangong-2. The station made a controlled reentry on 19 July 2019 and burned up over the South Pacific Ocean. The
Tiangong Space Station (), the first module of which was launched on 29 April 2021, is in low Earth orbit, 340 to 450 kilometres above the Earth at an orbital inclination of 42° to 43°. The core module was extended in 2022 with two laboratory modules, bringing the total station capacity to six crew members. The station was completed on 5 November 2022.
Planned projects ==Architecture==