The International Space Station in front of the Earth. This image was taken by Space Shuttle Discovery while pulling away during STS-119.
The International Space Station in front of the Earth. This image was taken by Space Shuttle Discovery while pulling away during STS-119.
Skylab viewed from the command module of Skylab 2
Skylab viewed from the command module of Skylab 2

A space station is a spacecraft capable of supporting a human crew in orbit for an extended period of time, and is therefore a type of space habitat. It lacks major propulsion or landing systems. An orbital station or an orbital space station is an artificial satellite (i.e. a type of orbital spaceflight). Stations must have docking ports to allow other spacecraft to dock to transfer crew and supplies. The purpose of maintaining an orbital outpost varies depending on the program. Space stations have most often been launched for scientific purposes, but military launches have also occurred.

Space stations have harboured so far the only long-duration direct human presence in space. After the first station Salyut 1 (1971) and its tragic Soyuz 11 crew, space stations have been operated consecutively since Skylab (1973), having allowed a progression of long-duration direct human presence in space. Stations have been occupied by consecutive crews since 1987 with the Salyut successor Mir. Uninterrupted occupation of stations has been achived since the operational transition from the Mir to the ISS, with its first occupation in 2000. The ISS has hosted the highest number of people in orbit at the same time, reaching 13 for the first time during the eleven day docking of STS-127 in 2009.

As of 2022, there are two fully operational space stations in low Earth orbit (LEO) – the International Space Station (ISS) and China's Tiangong Space Station (TSS). While the ISS has been permanently inhabited since October 2000 with the Expedition 1 crews, the TSS will do so with the Shenzhou 14 crews in June 2022. The ISS is used to study the effects of spaceflight on the human body, as well as to provide a location to conduct a greater number and longer length of scientific studies than is possible on other space vehicles. China's Tiangong Space Station is scheduled to finish its phase 1 construction by the end of 2022 with the addition of two lab modules. India has also proposed to build a space station in the coming decades. There have been numerous decommissioned space stations, including USSR's Salyuts, Russia's Mir, NASA's Skylab, and China's Tiangong 1 and 2.

Past stations

These stations have re-entered the atmosphere and disintegrated.

The Soviet Union ran two programs simultaneously in the 1970s, both of which were called Salyut publicly. The Long Duration Orbital Station (DOS) program was intended for scientific research into spaceflight. The Almaz program was a secret military program that tested space reconnaissance.[1]

  double-dagger     = Never crewed

Name Program
Entity
Crew
size
Launched Reentered Days
in orbit
Days
occu-
pied
Total crew
and visitors
Number of
crewed visits
Number of
robotic visits
Mass
(* = at launch)
Pressurized
volume
Salyut 1 DOS[2] 3[3] 19 April 1971[4] 11 October 1971[5] 175 24[6] 6[7] 2[7] 0[7] 18,425 kg (40,620 lb)[4] 100 m3 (3,500 cu ft)[8]
Soviet Union MOM[9]
DOS-2double-dagger DOS[10] [a] 29 July 1972[4][11] 29 July 1972 failed to reach orbit 18,000 kg (40,000 lb)[12]
Soviet Union RVSN[13]
Salyut 2double-dagger Almaz[11] [a] 3 April 1973[11] 16 April 1973[11] 13[11] 18,500 kg (40,800 lb)[14]
Soviet Union MOM[15]
Kosmos 557double-dagger DOS[16] [a] 11 May 1973[17] 22 May 1973[18] 11 19,400 kg (42,800 lb)[12]
Soviet Union USSR
Skylab Skylab[19] 3[20] 14 May 1973[21] 11 July 1979[22] 2249 171[23] 9[24] 3[25] 0[26] 77,088 kg (169,950 lb)[27] 360 m3 (12,700 cu ft)[28]
United States NASA
Salyut 3 Almaz[2] 2[29] 25 May 1974[30] 24 January 1975[31] 213 15[32] 2[32] 1[32] 0 18,900 kg (41,700 lb)*[33] 90 m3 (3,200 cu ft)[16]
Soviet Union MOM[15]
Salyut 4 DOS[34] 2[35] 26 December 1974[36] 3 February 1977[36] 770[36] 92[37] 4[37] 2[37][38] 1[37] 18,900 kg (41,700 lb)[16]* 90 m3 (3,200 cu ft)[16]
Soviet Union MOM[13]
Salyut 5 Almaz[34] 2[39] 22 June 1976[40] 8 August 1977[41] 412 67[42] 4[42] 3[42] 0[42] 19,000 kg (42,000 lb)[16]* 100 m3 (3,500 cu ft)[16]
Soviet Union MOM[15]
Salyut 6 DOS[34][43] 2[44] 29 September 1977[44] 29 July 1982[45] 1764 683[46] 33[46] 16[46] 14[46] 19,000 kg (42,000 lb)[47] 90 m3 (3,200 cu ft)[48]
Soviet Union MOM[15]
Salyut 7 DOS[34][43] 3[49] 19 April 1982[50] 7 February 1991[50] 3216[50] 861[49] 22[49] 10[49] 15[49] 19,000 kg (42,000 lb)[51] 90 m3 (3,200 cu ft)[16]
Soviet Union MOM[15]
Mir DOS[34][43] 3[52] 19 February 1986[53][b] 23 March 2001[22][53] 5511[53] 4594[54] 125[54] 39[55] 68[54] 129,700 kg (285,900 lb)[56] 350 m3 (12,400 cu ft)[57]
Tiangong-1 Tiangong 3[58] 29 September 2011[59][60] 2 April 2018[61] 2377 22 6[62][63] 2[62] 1[64] 8,506 kg (18,753 lb)[65] 15 m3 (530 cu ft)[66]
China CMSA
Tiangong-2 Tiangong 2 15 September 2016 19 July 2019 1037 29 2 1 1 8,506 kg (18,753 lb)[65] 15 m3 (530 cu ft)[66]
China CMSA

Note: Prototypes and various parts of Chinese, Japanese, and Russian, U.S. programs are in orbit, but not necessarily operational.

Prototypes

These stations and parts are prototypes; they only exist as testing platforms and will never be crewed. OPS 0855 was part of a cancelled Manned Orbiting Laboratory project by the United States, while the Genesis stations were launched privately. The Genesis stations were "retired" when their avionics systems stopped working after two and a half years, yet they still remain in orbit thus become derelict spacecrafts

Name Entity Program Launched Reentered Days in orbit Mass Pressurized volume
OPS 0855 United States USAF MOL 3 November 1966[67] 9 January 1967[67] 67 9,680 kg (21,340 lb) 11.3 m3 (400 cu ft)
Genesis I United States Bigelow Aerospace 12 July 2006[68] (In Orbit) 5823 1,360 kg (3,000 lb)[69] 11.5 m3 (410 cu ft)[70]
Genesis II 28 June 2007[68] 5472 11.5 m3 (406 cu ft)[70]

Operational stations

As of 2022, two stations are orbiting Earth with life support system in place and fully operational.

Name Entity Crew size Launched Days in orbit[c] Days
occupied
Total crew
and visitors
Crewed
visits
Robotic
visits
Mass Pressurized
volume
International Space Station 7[71] 20 November 1998[71][b] 8614 7903[72] 230[73] 88 [74] 94 [74] 419,725 kg (925,335 lb)[75] 915.6 m3 (32,300 cu ft)[76]
Tiangong space station 3-6[77] 29 April 2021 418 288 9 3 3 22,600 kg (49,800 lb) 110 m3 (3,880 cu ft) (planned)

Planned and proposed

These space stations have been announced by their host entity and are currently in planning, development or production. The launch date listed here may change as more information becomes available.

Name Entity Program Crew size Launch date Remarks
Lunar Gateway United States NASA
ESA logo simple.svg
ESA
Canada CSA
Japan JAXA
Artemis
4
November 2024[78][79] Intended to serve as a science platform and as a staging area for the lunar landings of NASA's Artemis program and follow-on human mission to Mars.
Axiom Station United States Axiom Space
International Space Station programme
TBD
2024 [80] Eventually will detach from the ISS in the late 2020s and form a private, free flying space station for commercial tourism and science activities.
Russian Orbital Service Station
(ROSS)
Russia Roscosmos Russia's next generation space station.
TBD
2025[81] With Russia leaving the ISS programme in 2024, Roscosmos announced this new space station in April 2021 as the replacement for that program.
Starlab Space Station United States NanoRacks
United States Voyager Space
United States Lockheed Martin
Private
4
2027 [82] "Commercial platform supporting a business designed to enable science, research, and manufacturing for customers around the world."
Orbital Reef Station United States Blue Origin
United States Sierra Space
Private
10
second half 2020s [83] "Commercial station in LEO for research, industrial, international, and commercial customers."
TBD India ISRO Indian Human Spaceflight Programme
3
~2030[84][85][86][87] ISRO chairman K. Sivan announced in 2019 that India will not join the International Space Station and will instead build a 20 tonne space station on its own.[88] It is intended to be built in the next 5–7 years,[89]
Lunar Orbital Station[90]
(LOS)
Russia Roscosmos
TBD
after 2030[91]
TBD United States Northrop Grumman Private
4-8[92]
"to provide a base module for extended capabilities including science, tourism, industrial experimentation" [93]

Canceled projects

The interior of Skylab, on display at the Smithsonian's National Air and Space Museum
The interior of Skylab, on display at the Smithsonian's National Air and Space Museum

Most of these stations were canceled due to financial difficulties. However, Mir-2 was merged to Freedom and formed the basis of the International Space Station.

Name Entity Crew size Remarks
Manned Orbiting Laboratory 1–7 United States NASA 2[94] Canceled due to excessive costs in 1969[95]
Skylab B United States NASA 3[96] Constructed, but launch canceled due to lack of funding.[97] Now a museum piece.
OPS-4 Soviet Union USSR Constructed but never launched, due to cancellation of the Almaz program.
Freedom United States NASA 14–16[98] Merged to form the basis of the International Space Station
Mir-2 Soviet Union USSR
Russia Roscosmos
2[99]
Columbus MTFF
ESA logo simple.svg
ESA
3 (visiting from Hermes)
Galaxy United States Bigelow Aerospace Robotic[100] Canceled due to rising costs and ability to ground test key Galaxy subsystems[101]
Almaz commercial United Kingdom Excalibur Almaz 4 or more Lack of funds.
OPSEK Russia Roscosmos More than 2 Canceled in 2017. OPSEK components will instead remain attached to the ISS.

Timeline

Tiangong space stationTiangong 2Tiangong 1Genesis II (space habitat)Genesis IInternational Space StationMirSalyut 7Salyut 6Salyut 5Salyut 4Salyut 3SkylabKosmos 557Salyut 2DOS-2Salyut 1OPS 0855
The image above contains clickable links
Timeline of space stations, sorted by the nations that launched them. Prototype stations are marked*.
  China
  Soviet Union/Russia
  USA
  multiple nations


Size comparison

International Space StationTiangong Space StationMirSkylabTiangong-2Salyut 1Salyut 2Salyut 4Salyut 6Salyut 7
The image above contains clickable links
Size comparisons between current and past space stations as they appeared most recently. Solar panels in blue, heat radiators in red. Note that stations have different depths not shown by silhouettes.

See also

Notes

  1. ^ a b c The USSR intended to crew these stations with 2 men, however they re-entered the atmosphere before the cosmonauts were launched.
  2. ^ a b Launch date of the initial module. Additional modules for this station were launched later.
  3. ^ Correct as of 21 June 2022

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