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 the deaths of its 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 achieved 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. On May 30, 2023 there were 11 people on the ISS and 6 on China's TSS: with a total of 17 people in orbit, it set the record for most people in orbit as of 2023. [1]
As of 2024, there are two fully operational space stations in low Earth orbit (LEO) – the International Space Station (ISS) and China's Tiangong Space Station (TSS). The ISS has been permanently inhabited since October 2000 with the Expedition 1 crews and the TSS began continuous inhabitation with the Shenzhou 14 crews in June 2022. These stations are 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. In 2022, the TSS finished its phase 1 construction with the addition of two lab modules: Wentian ("Quest for the Heavens"), launched on 24 July 2022, and Mengtian ("Dreaming of the Heavens") launched on 31 October 2022, joining the ISS as the most recent space station operating in orbit. In July 2022, Russia announced intentions to withdraw from the ISS after 2024 in order to build its own space station. [2] There have been numerous decommissioned space stations, including the USSR's Salyuts and Mir, NASA's Skylab, and China's Tiangong 1 and Tiangong 2.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. [3]
‡ = 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 [4] | 3 [5] | 19 April 1971 [6] | 11 October 1971 [7] | 175 | 24 [8] | 6 [9] | 2 [9] | 0 [9] | 18,425 kg (40,620 lb) [6] | 100 m3 (3,500 cu ft) [10] |
MOM [11] | |||||||||||
DOS-2‡ | DOS [12] | — [a] | 29 July 1972 [6] [13] | 29 July 1972 | failed to reach orbit | — | — | — | — | 18,000 kg (40,000 lb) [14] | — |
RVSN [15] | |||||||||||
Salyut 2‡ | Almaz [13] | — [a] | 3 April 1973 [13] | 16 April 1973 [13] | 13 [13] | — | — | — | — | 18,500 kg (40,800 lb) [16] | — |
MOM [17] | |||||||||||
Kosmos 557‡ | DOS [18] | — [a] | 11 May 1973 [19] | 22 May 1973 [20] | 11 | — | — | — | — | 19,400 kg (42,800 lb) [14] | — |
USSR | |||||||||||
Skylab | Skylab [21] | 3 [22] | 14 May 1973 [23] | 11 July 1979 [24] | 2249 | 171 [25] | 9 [26] | 3 [27] | 0 [28] | 77,088 kg (169,950 lb) [29] | 360 m3 (12,700 cu ft) [30] |
NASA | |||||||||||
Salyut 3 | Almaz [4] | 2 [31] | 25 June 1974 [32] | 24 January 1975 [33] | 213 | 15 [34] | 2 [34] | 1 [34] | 0 | 18,900 kg (41,700 lb)* [35] | 90 m3 (3,200 cu ft) [18] |
MOM [17] | |||||||||||
Salyut 4 | DOS [36] | 2 [37] | 26 December 1974 [38] | 3 February 1977 [38] | 770 [38] | 92 [39] | 4 [39] | 2 [39] [40] | 1 [39] | 18,900 kg (41,700 lb) [18]* | 90 m3 (3,200 cu ft) [18] |
MOM [15] | |||||||||||
Salyut 5 | Almaz [36] | 2 [41] | 22 June 1976 [42] | 8 August 1977 [43] | 412 | 67 [44] | 4 [44] | 3 [44] | 0 [44] | 19,000 kg (42,000 lb) [18]* | 100 m3 (3,500 cu ft) [18] |
MOM [17] | |||||||||||
Salyut 6 | DOS [36] [45] | 2 [46] | 29 September 1977 [46] | 29 July 1982 [47] | 1764 | 683 [48] | 33 [48] | 16 [48] | 14 [48] | 19,000 kg (42,000 lb) [49] | 90 m3 (3,200 cu ft) [50] |
MOM [17] | |||||||||||
Salyut 7 | DOS [36] [45] | 3 [51] | 19 April 1982 [52] | 7 February 1991 [52] | 3216 [52] | 861 [51] | 22 [51] | 10 [51] | 15 [51] | 19,000 kg (42,000 lb) [53] | 90 m3 (3,200 cu ft) [18] |
MOM [17] | |||||||||||
Mir | DOS [36] [45] | 3 [54] | 19 February 1986 [55] [b] | 23 March 2001 [24] [55] | 5511 [55] | 4594 [56] | 125 [56] | 39 [57] | 68 [56] | 129,700 kg (285,900 lb) [58] | 350 m3 (12,400 cu ft) [59] |
| |||||||||||
Tiangong-1 | Tiangong | 3 [60] | 29 September 2011 [61] [62] | 2 April 2018 [63] | 2377 | 22 | 6 [64] [65] | 2 [64] | 1 [66] | 8,506 kg (18,753 lb) [67] | 15 m3 (530 cu ft) [68] |
CMSA | |||||||||||
Tiangong-2 | Tiangong | 2 | 15 September 2016 | 19 July 2019 | 1037 | 29 | 2 | 1 | 1 | 8,506 kg (18,753 lb) [67] | 15 m3 (530 cu ft) [68] |
CMSA |
These stations are prototypes; they only exist as testing platforms and were never intended to 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 as derelict spacecraft.
Name | Entity | Program | Launched | Reentered | Days in orbit | Mass | Pressurized volume |
---|---|---|---|---|---|---|---|
OPS 0855 | USAF | MOL | 3 November 1966 [69] | 9 January 1967 [69] | 67 | 9,680 kg (21,340 lb) | 11.3 m3 (400 cu ft) |
Genesis I | Bigelow Aerospace | 12 July 2006 [70] | (In Orbit) | 6469 | 1,360 kg (3,000 lb) [71] | 11.5 m3 (410 cu ft) [72] | |
Genesis II | 28 June 2007 [70] | 6118 | 11.5 m3 (406 cu ft) [72] |
As of 2024, 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 |
Habitable volume |
---|---|---|---|---|---|---|---|---|---|---|---|
International Space Station | 7 [73] | 20 November 1998 [73] [b] | 9260 | 8549 [74] | 230 [75] | 88 [76] | 94 [76] | 450,000 kg (990,000 lb) [77] | 1,005 m3 (35,500 cu ft) [78] | 388 m3 (13,700 cu ft) | |
Tiangong space station | 3–6 [79] | 29 April 2021 | 1064 | 934 | 17 | 6 | 8 | 100,000 kg (220,000 lb) | 340 m3 (12,000 cu ft) | 122 m3 (4,310 cu ft) |
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 |
NASA ESA CSA JAXA |
Artemis | 4
|
2025 [80] | 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 |
Axiom Space |
International Space Station programme | TBD
|
Late 2026 [81] | Eventually will detach from the ISS in the early 2030s and form a private, free flying space station for commercial tourism and science activities. |
Russian Orbital Service Station |
Roscosmos | Russia's next generation space station. | TBD
|
2027 [82] | With Russia leaving the ISS programme sometime after 2024, Roscosmos announced this new space station in April 2021 as the replacement for that program. |
Starlab |
NanoRacks Voyager Space Lockheed Martin Airbus |
Private | 4
|
2028 [83] | "Commercial platform supporting a business designed to enable science, research, and manufacturing for customers around the world." |
StarMax | Gravitics | Private | TBD
|
2026 [84] | "The StarMax module provides up to 400 cubic meters of usable habitable volume - nearly half the volume of the International Space Station in one module." |
Orbital Reef |
Blue Origin Sierra Space |
Private | 10
|
second half 2020s [85] | "Commercial station in LEO for research, industrial, international, and commercial customers." |
Bharatiya Antariksha Station [86] | ISRO | Indian Human Spaceflight Programme | 3
|
~2035 [87] [88] [89] [90] [91] | ISRO chairman K. Sivan announced in 2019 that India will not join the International Space Station, but will instead build a 20 ton space station of its own. [92] It is intended to be built 5–7 years after the conclusion of the Gaganyaan program. [93] |
Lunar Orbital Station
[94] |
Roscosmos | TBD
|
after 2030 [95] | ||
Haven-1 | Vast | Private | 4
|
2025 [96] | "Scheduled to be the world's first commercial space station, Haven-1 and subsequent human spaceflight missions will accelerate access to space exploration" [97] |
LIFE Pathfinder | Sierra Space | Private | TBD
|
2026 | "Before offering LIFE for Orbital Reef, though, the company is proposing to launch a standalone “pathfinder” version of LIFE as soon as the end of 2026". [98] |
Most of these stations were canceled due to financial difficulties, or merged into other projects.
Name | Entity | Crew | Cancellation | Remarks |
---|---|---|---|---|
Manned Orbiting Laboratory 1–7 | USAF | 2 [99] | 1969 | Boilerplate mission launched successfully, wider project cancelled due to excessive costs [100] |
Skylab B | NASA | 3 [101] | 1976 | Constructed, but launch cancelled due to lack of funding. [102] Now a museum piece. |
OPS-4 | USSR | 3 [103] | 1979 | Constructed, but Almaz program cancelled in favour of uncrewed recon satellites. |
Freedom | NASA | 14–16 [104] | 1993 | Merged to form the basis of the International Space Station. |
Mir-2 |
USSR Roscosmos |
2 [105] | ||
Columbus MTFF | ESA | 3 | ||
Galaxy | Bigelow Aerospace | Robotic [106] | 2007 | Canceled due to rising costs and ability to ground test key Galaxy subsystems [107] |
Sundancer | 3 | 2011 | Was under construction, but cancelled in favour of developing B330. | |
Almaz commercial | Excalibur Almaz | 4+ | 2016 | Soviet hardware was acquired, but never launched due to lack of funds. |
Tiangong-3 | CNSA | 3 | 2017 | The goals for Tiangong-2 and 3 were merged, and were completed by a single station rather than two separate stations. |
OPSEK | Roscosmos | 2+ | 2017 | Some modules such as Nauka were launched and attached to the ISS- but proposals to split these off as a separate station were cancelled, and they instead remain part of the ISS. |
B330 | Bigelow Aerospace | 3 | 2020 | Test articles were constructed but not flight ready hardware; cancelled due to the COVID-19 pandemic. |
Ondler said in the briefing that the first of those modules is now scheduled to launch to the ISS at the end of 2026, about a year later than the company previously announced.