The process of assembling theInternational Space Station (ISS) has been under way since the 1990s.Zarya, the first ISS module, was launched by aProton rocket on 20 November 1998. TheSTS-88 Space Shuttle mission followed two weeks afterZarya was launched, bringingUnity, the first of three node modules, and connecting it toZarya. This bare 2-module core of the ISS remained uncrewed for the next one and a half years, until in July 2000 the Russian moduleZvezda was launched by a Proton rocket, allowing a maximum crew of three astronauts or cosmonauts to be on the ISS permanently.
The ISS has a pressurized volume of approximately 1,000 cubic metres (35,000 cu ft), a mass of approximately 410,000 kilograms (900,000 lb), approximately 100 kilowatts of power output, a truss 108.4 metres (356 ft) long, modules 74 metres (243 ft) long, and a crew of seven.[1] Building the complete station required more than 40 assembly flights. As of 2020,36 Space Shuttle flights delivered ISS elements. Other assembly flights consisted of modules lifted by theFalcon 9, RussianProton rocket or, in the case ofPirs andPoisk, theSoyuz-U rocket.
Some of the larger modules include:
Thespace station is located inorbit around theEarth at an altitude of approximately 410 km (250 mi), a type of orbit usually termedlow Earth orbit (the actual height varies over time by several kilometers due toatmospheric drag andreboosts). It orbits Earth in aperiod of about 90 minutes; by August 2007 it had completed more than 50,000 orbits since launch ofZarya on 20 November 1998.
A total of 14 main pressurized modules were scheduled to be part of the ISS by its completion date in 2010.[2] A number of smaller pressurized sections will be adjunct to them (Soyuz spacecraft (permanently 2 as lifeboats – 6 months rotations),Progress transporters (2 or more), theQuest andPirs airlocks, as well as periodically theH-II Transfer Vehicle).
TheUS Orbital Segment was completed in 2011 after the installation of theAlpha Magnetic Spectrometer during theSTS-134 mission. TheRussian Orbital Segment assembly has been on an indefinite hiatus since the installation of theRassvet module in 2010 during theSTS-132 mission. TheRassvet module on the ISS right now was originally supposed to be the on-ground dynamic testing mock-up of the now-cancelledScience Power Platform. TheNauka science laboratory module contains new crew quarters, life support equipment that can produce oxygen and water, and a new galley. TheNauka was originally supposed to be delivered to the ISS in 2007 but cost overruns and quality control problems delayed it for over a decade. TheNauka module finally launched in July 2021 and docked to the nadir port of Zvezda module after several days of free flight[3] followed by thePrichal which launched on 24 November 2021.
There are plans to add 2 or 3 more modules that would attach toPrichal during the mid-2020s. Adding more Russian modules will help theZvezda module greatly becauseZvezda's originally installed central command computers no longer work (threeThinkPad laptops are now theZvezda's central command computers) and itsElektron oxygen generators are not replaceable and failed again for a short time in 2020 after multiple malfunctions throughout their history.[4] In Russian modules all the hardware is launched with the equipment permanently installed. It is impossible to replace hardware like in the US Orbital Segment with its very wide 51 inch (105 cm) hatch openings between modules. This potential problem with theZvezda was made apparent when in October 2020 the toilet, oven, and Elektron all malfunctioned at the same time and the cosmonauts onboard had to make emergency repairs.[5]
The ISS, when completed, will consist of a set of communicating pressurized modules connected to atruss, on which four large pairs ofphotovoltaic modules (solar panels) are attached. The pressurized modules and the truss are perpendicular: the truss spanning fromstarboard toport and the habitable zone extending on theaft-forward axis. Although during the construction the stationattitude may vary, when all four photovoltaic modules are in their definitive position the aft-forward axis will be parallel to the velocity vector.[6]
In addition to the assembly and utilization flights, approximately 30 Progress spacecraft flights are required to provide logistics until 2010. Experimental equipment, fuel and consumables are and will be delivered by all vehicles visiting the ISS: theSpaceX Dragon, the Russian Progress, the EuropeanATV and the JapaneseHTV, and space stationdownmass will be carried back to Earth facilities on the Dragon.[7]
After theSpace ShuttleColumbia disaster on 1 February 2003, there was some uncertainty over the future of the ISS. The subsequent two and a half-year suspension of the U.S.Space Shuttle program, followed by problems with resuming flight operations in 2005, were major obstacles.[citation needed]
The Space Shuttle program resumed flight on 26 July 2005, with theSTS-114 mission ofDiscovery. This mission to the ISS was intended both to test new safety measures implemented since theColumbia disaster and deliver supplies to the station. Although the mission succeeded safely, it was not without risk; foam was shed by theexternal tank, leading NASA to announce future missions would be grounded until this issue was resolved.[citation needed]
Between theColumbia disaster and the resumption of Shuttle launches, crew exchanges were carried out solely using the RussianSoyuz spacecraft. Starting withExpedition 7, two-astronaut caretaker crews were launched in contrast to the previously launched crews of three. Because the ISS had not been visited by a shuttle for an extended period, a larger than planned amount of waste accumulated, temporarily hindering station operations in 2004. HoweverProgress transports and theSTS-114 shuttle flight took care of this problem.[citation needed]
Many changes were made to the originally planned ISS, even before theColumbia disaster. Modules and other structures were cancelled or replaced, and the number of Shuttle flights to the ISS was reduced from previously planned numbers. However, more than 80% of the hardware intended to be part of the ISS in the late 1990s was orbited and is now part of the ISS's configuration.[citation needed]
During the shuttle stand-down, construction of the ISS was halted and the science conducted aboard was limited due to the crew size of two, adding to earlier delays due to Shuttle problems and the Russian space agency's budget constraints.[citation needed]
In March 2006, a meeting of the heads of the five participating space agencies accepted the new ISS construction schedule that planned to complete the ISS by 2010.[8]
As of May 2009, a crew of six has been established following 12 Shuttle construction flights after the second "Return to Flight" missionSTS-121. Requirements for stepping up the crew size included enhanced environmental support on the ISS, a second Soyuz permanently docked on the station to function as a second 'lifeboat', more frequent Progress flights to provide double the amount of consumables, more fuel for orbit raising maneuvers, and a sufficient supply line of experimental equipment.[citation needed] As of November 2020, the crew capacity has increased to seven due to the launch ofCrew Dragon bySpaceX, which can carry 4 astronauts to the ISS.
Later additions included theBigelow Expandable Activity Module (BEAM) in 2016, and numerous Russian components are planned as part of the in-orbit construction ofOPSEK.[citation needed]
The ISS is made up of 16 pressurized modules: six Russian modules (Zarya,Zvezda,Poisk,Rassvet,Nauka, andPrichal), eight US modules (BEAM,[9]Leonardo,Harmony,Quest,Tranquility,Unity,Cupola, andDestiny), one Japanese module (Kibō) and one European module (Columbus).
At least one Russian pressurized module (Pirs) is deorbited till now.[10]
Although not permanently docked with the ISS,Multi-Purpose Logistics Modules (MPLMs) formed part of the ISS during some Shuttle missions. An MPLM was attached toHarmony (initially toUnity) and was used for resupply and logistics flights.[citation needed]
Spacecraft attached to the ISS also extend the pressurized volume. At least one Soyuz spacecraft is always docked as a 'lifeboat' and is replaced every six months by a new Soyuz as part of crew rotation. Table below shows the sequence in which these components were added to the ISS.[11] Decommissioned and deorbited Modules are shown in gray.
| Element | Assembly flight | Launch date | Launch vehicle | Length | Diameter | Mass | Isolated View | Station View |
|---|---|---|---|---|---|---|---|---|
| Zarya (FGB) | 1A/R | 1998-11-20 | Proton-K | 12.56 m (41.2 ft) | 4.1 m (13 ft) | 24,968 kg (55,045 lb) |  | |
| Unity (Node 1) | 2A | 1998-12-04 | Space Shuttle Endeavour (STS-88) | 5.5 m (18 ft) | 4.3 m (14 ft) | 11,895 kg (26,224 lb) |  |  |
| PMA-1 | 1.86 m (6 ft 1 in) | 1.9 m (6 ft 3 in) | 1,589 kg (3,503 lb) |  | ||||
| PMA-2 | 1.86 m (6 ft 1 in) | 1.9 m (6 ft 3 in) | 1,376 kg (3,034 lb) | | ||||
| Zvezda (Service Module) | 1R | 2000-07-12 | Proton-K | 13.1 m (43 ft) | 4.2 m (14 ft) | 24,604 kg (54,243 lb) |  |  |
| Z1 Truss | 3A | 2000-10-11 | Space Shuttle Discovery (STS-92) | 4.6 m (15 ft) | 4.2 m (14 ft) | 8,755 kg (19,301 lb) |  |  |
| PMA-3 | 1.86 m (6 ft 1 in) | 1.9 m (6 ft 3 in) | 1,183 kg (2,608 lb) | | ||||
| P6 Truss & Solar Arrays | 4A | 2000-11-30 | Space Shuttle Endeavour (STS-97) | 18.3 m (60 ft) | 10.7 m (35 ft) deployed | 15,824 kg (34,886 lb) |  | |
| Destiny (US Laboratory) | 5A | 2001-02-07 | Space Shuttle Atlantis (STS-98) | 9.2 m (30 ft) | 4.3 m (14 ft) | 14,515 kg (32,000 lb) |  |  |
| ESP-1 | 5A.1 | 2001-03-08 | Space Shuttle Discovery (STS-102) | 2.4 m (7 ft 10 in) | 0.46 m (1 ft 6 in) |  |  | |
| Canadarm2 (SSRMS) | 6A | 2001-04-19 | Space Shuttle Endeavour (STS-100) | 17.6 m (58 ft) | 35 cm (14 in) | 1,800 kg (4,000 lb) |  |  |
| Quest (Joint Airlock) | 7A | 2001-07-12 | Space Shuttle Atlantis (STS-104) | 5.5 m (18 ft) | 4.0 m (13.1 ft) | 9,923 kg (21,876 lb) |  |  |
| Pirs (Docking Compartment) | 4R | 2001-09-14 | Soyuz-U (Progress M-SO1) | 4.9 m (16 ft) | 2.55 m (8.4 ft) | 3,838 kg (8,461 lb) |  |  |
| S0 Truss[12] | 8A | 2002-04-08 | Space Shuttle Atlantis (STS-110) | 13.4 m (44 ft) | 4.6 m (15 ft) | 13,971 kg (30,801 lb) |  |  |
| Mobile Base System | UF2 | 2002-06-05 | Space Shuttle Endeavour (STS-111) | 1,438 kg (3,170 lb) |  |  | ||
| S1 Truss | 9A | 2002-10-07 | Space Shuttle Atlantis (STS-112) | 13.7 m (45 ft) | 4.6 m (15 ft) | 14,124 kg (31,138 lb) |  |  |
| P1 Truss | 11A | 2002-11-23 | Space Shuttle Endeavour (STS-113) | 13.7 m (45 ft) | 4.6 m (15 ft) | 14,003 kg (30,871 lb) |  |  |
| ESP-2 | LF1 | 2005-07-26 | Space Shuttle Discovery (STS-114) | 2.6 m (8 ft 6 in) | 4.3 m (14 ft) |  |  | |
| P3/P4 Truss & Solar Arrays[13] | 12A | 2006-09-09 | Space Shuttle Atlantis (STS-115) | 13.7 m (45 ft) | 4.6 m (15 ft) | 15,824 kg (34,886 lb) |  |  |
| P5 Truss[14] | 12A.1 | 2006-12-09 | Space Shuttle Discovery (STS-116) | 3.37 m (11.1 ft) | 4.55 m (14.9 ft) | 1,864 kg (4,109 lb) | .jpg) |  |
| S3/S4 Truss & Solar Arrays | 13A | 2007-06-08 | Space Shuttle Atlantis (STS-117) | 13.7 m (45 ft) | 10.7 m (35 ft) | 15,824 kg (34,886 lb) |  |  |
| S5 Truss | 13A.1 | 2007-08-08 | Space Shuttle Endeavour (STS-118) | 3.37 m (11.1 ft) | 4.55 m (14.9 ft) | 1,864 kg (4,109 lb) | .jpg) |  |
| ESP-3 | 2.6 m (8 ft 6 in) | 4.3 m (14 ft) |  | |||||
| Harmony (Node 2) | 10A | 2007-10-23 | Space Shuttle Discovery (STS-120) | 7.2 m (24 ft) | 4.4 m (14 ft) | 14,300 kg (31,500 lb) |  |  |
| Relocation of P6 Truss | 18.3 m (60 ft) | 10.7 m (35 ft) deployed | 15,824 kg (34,886 lb) | .jpg) | ||||
| Columbus (European Laboratory)[15] | 1E | 2008-02-07 | Space Shuttle Atlantis (STS-122) | 7 m (23 ft) | 4.5 m (15 ft) | 12,800 kg (28,219 lb) |  |  |
| Dextre (SPDM) | 1J/A | 2008-03-11 | Space Shuttle Endeavour (STS-123) | 3.5 m (11 ft) | 7 m (23 ft) outstretched | 1,662 kg (3,664 lb) |  |  |
| Experiment Logistics Module (ELM) | 4.21 m (13.8 ft) | 4.39 m (14.4 ft) | 8,386 kg (18,488 lb) |  | ||||
| JEM Pressurized Module (JEM-PM)[16][17] | 1J | 2008-05-31 | Space Shuttle Discovery (STS-124) | 11.19 m (36.7 ft) | 4.39 m (14.4 ft) | 15,900 kg (35,100 lb) |  |  |
| JEM Remote Manipulator System (JEMRMS) | 10 m (33 ft) | |||||||
| S6 Truss & Solar Arrays | 15A | 2009-03-15 | Space Shuttle Discovery (STS-119) | 18.3 m (60 ft) | 10.7 m (35 ft) deployed | 15,824 kg (34,886 lb) | |  |
| Kibo Exposed Facility (JEM-EF) | 2J/A | 2009-07-15 | Space Shuttle Endeavour (STS-127) |  |  | |||
| Poisk (MRM-2)[18][19] | 5R | 2009-11-10 | Soyuz-U (Progress M-MIM2) | 4.049 m (13.28 ft) | 2.55 m (8 ft 4 in) | 3,670 kg (8,090 lb) |  |  |
| ELC-1 | ULF3 | 2009-11-16 | Space Shuttle Atlantis (STS-129) | 6,280 kg (13,850 lb) |  |  | ||
| ELC-2 | 6,100 kg (13,400 lb) | | ||||||
| Tranquility (Node 3) | 20A | 2010-02-08 | Space Shuttle Endeavour (STS-130) | 6.706 m (22.00 ft) | 4.48 m (14.7 ft) | 19,000 kg (42,000 lb) |  |  |
| Cupola | 1.5 m (4 ft 11 in) | 2.95 m (9 ft 8 in) | 1,880 kg (4,140 lb) |  | ||||
| Rassvet (MRM-1)[20] | ULF4 | 2010-05-14 | Space Shuttle Atlantis (STS-132) | 6 m (20 ft) | 2.35 m (7 ft 9 in) | 8,015 kg (17,670 lb) |  |  |
| Nauka Science Airlock | 1,050 kg (2,310 lb) | |||||||
| Nauka RTOd Radiator | ||||||||
| ERA portable workpost | ||||||||
| Leonardo (PMM) | ULF5 | 2011-02-24 | Space Shuttle Discovery (STS-133) | 6.6 m (22 ft) | 4.57 m (15.0 ft) | 4,082 kg (8,999 lb) |  |  |
| ELC-4 | 3,735 kg (8,234 lb) | | ||||||
| AMS-02 | ULF6 | 2011-05-16 | Space Shuttle Endeavour (STS-134) | 7,500 kg (16,500 lb) |  |  | ||
| OBSS | 15.24 m (50.0 ft) | 35 cm (14 in) |  | |||||
| ELC-3 | 6,361 kg (14,024 lb) | | ||||||
| HRSGF | CRS SpX-2 | 2013-03-13 | Falcon 9 (SpaceX CRS-2) | |||||
| BEAM[21] | CRS SpX-8 | 2016-04-08 | Falcon 9 (SpaceX CRS-8) | 4.01 m (13.2 ft) | 3.23 m (10.6 ft) | 1,413 kg (3,115 lb) |  | .jpg) |
| IDA-2[22][23] | CRS SpX-9 | 2016-07-18 | Falcon 9 (SpaceX CRS-9) | 110 cm (43 in) | 160 cm (63 in) | 526 kg (1,160 lb) |  | |
| IDA-3[24] | CRS SpX-18 | 2019-07-25 | Falcon 9 (SpaceX CRS-18) | 110 cm (43 in) | 160 cm (63 in) | 526 kg (1,160 lb) | ||
| Bartolomeo[25] | CRS SpX-20 | 2020-03-06 | Falcon 9 (SpaceX CRS-20). | |||||
| Nanoracks Bishop Airlock | CRS SpX-21 | 2020-12-06 | Falcon 9 (SpaceX CRS-21) | 1.80 m (5 ft 11 in) | 2.014 m (6 ft 7.3 in) | 1,059 kg (2,335 lb) |  | |
| iROSA 1 and 2 | CRS SpX-22 | 2021-06-03 | Falcon 9 (SpaceX CRS-22) | 325 kg (717 lb) | _(4).jpg) | .jpg) | ||
| Nauka (MLM-U)[26] | 3R | 2021-07-21 | Proton-M | 13 m (43 ft) | 4.25 m (13.9 ft) | 20,300 kg (44,800 lb) |  | .jpg) |
| European Robotic Arm | 11.3 m (37 ft) | 630 kg (1,390 lb) | ||||||
| Nauka SSPA-GM temporary docking adapter | ||||||||
| MLM Means of Attachment of Large payloads (LCCS Part) | 79P | 2021-10-28 | Soyuz 2.1a (Progress MS-18) | |||||
| Prichal | 6R | 2021-11-24 | Soyuz 2.1b (Progress M-UM) | 4.91 m (16.1 ft) | 3.3 m (11 ft) | 3,890 kg (8,580 lb) | .jpg) | |
| MLM Means of Attachment of Large payloads (SCCS Part) | 82P | 2022-10-26 | Soyuz 2.1a (Progress MS-21) | |||||
| iROSA 3 and 4 | CRS SpX-26 | 2022-11-26 | Falcon 9 (SpaceX CRS-26) | 325 kg (717 lb) | | |||
| iROSA 5 and 6 | CRS SpX-28 | 2023-06-05 | Falcon 9 (SpaceX CRS-28) | 325 kg (717 lb) | |
The following module was built, but has not been used in future plans for the ISS as of January 2021.
TheISS is credited as the most expensive item ever built, costing around $150 billion (USD),[36] making it more expensive than Skylab (costing US$2.2 billion)[37] and Mir (US$4.2 billion).[38]
[Dragon's] ability to return goods is currently unique because all the other regular supply ships – Europe's Automated Transfer Vehicle (ATV), Japan's HTV (or "Kounotori") and Russia's Progress – all burn up during controlled re-entry.
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