Assembly of the International Space Station

An artist's impression of the International Space Station's configuration as of March 2011.

Cosmonaut Sergei Krikalev inside the Zvezda Service Module, November 2000.

The assembly of the International Space Station is a major aerospace engineering endeavour being conducted in Low Earth orbit by a consortium of governmental and inter-governmental space agencies.

Zarya, the first ISS module, was launched by a Proton rocket on 20 November 1998. The STS-88 shuttle mission followed two weeks after Zarya was launched, bringing Unity, the first of three node modules, and connecting it to Zarya. This bare 2-module core of the ISS remained unmanned for the next one and a half years, until in July 2000 the Russian module Zvezda was added, allowing a minimum crew of two astronauts or cosmonauts to be on the ISS permanently.

When assembly is complete, the ISS will have a pressurized volume of approximately 1,000 cubic meters, a mass of approximately 400,000 kilograms, approximately 100 kilowatts of power output, a truss 108.4 meters long, modules 74 meters long, and a crew of six. Building the complete station will require more than 40 assembly flights. As of March 2011, 26 Space Shuttle flights have docked with ISS to add elements, and 9 other Shuttle flights have flown logistics-servicing missions to ISS without adding major external elements. These 35 Shuttle missions include 9 SpaceHab and 10 MPLM logistics-servicing missions in various combinations. The last two planned Shuttle flights are due to add one of the two final elements of ISS, followed by one last Proton launch with the planned delivery of the ERA. Other assembly flights have consisted of modules lifted by the Russian Proton rocket or in the case of Pirs and Poisk by a Soyuz-U rocket.

Logistics

International Space Station mockup at Johnson Space Center in Houston, Texas.

The space station is located in orbit around the Earth at an altitude of approximately 360 km (220 mi), a type of orbit usually termed low Earth orbit (the actual height varies over time by several kilometers due to atmospheric drag and reboosts). It orbits Earth in a period of about 90 minutes; by August 2007 it had completed more than 50,000 orbits since launch of Zarya on 20 November 1998.

A total of 14 main pressurized modules are scheduled to be part of the ISS by its completion date in 2010.^[1] 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), the Quest and Pirs airlocks, as well as periodically the Multi-Purpose Logistics Module, the Automated Transfer Vehicle and the H-II Transfer Vehicle).

The ISS, when completed, will consist of a set of communicating pressurized modules connected to a truss, on which four large pairs of photovoltaic modules (solar panels) are attached. The pressurized modules and the truss will be perpendicular: the truss spanning from starboard to port and the habitable zone extending on the aft-forward axis. Although during the construction the station attitude may vary, when all four photovoltaic modules are in their definitive position the aft-forward axis will be parallel to the velocity vector.^[2]

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: the Shuttle, the Russian Progress, the European ATV and the Japanese HTV.

Columbia disaster and changes in construction plans

Columbia lifting off on its final mission.

Disaster and consequences

10 March 2001 - The Leonardo Multi-Purpose Logistics Module rests in Discovery's payload bay during STS-102.

At one point, there was some uncertainty over the future of the ISS. The Space Shuttle Columbia disaster on 1 February 2003, 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.

The Space Shuttle program resumed flight on 26 July 2005, with the STS-114 mission of Discovery. This mission to the ISS was intended both to test new safety measures implemented since the Columbia disaster, and to deliver supplies to the station. Although the mission succeeded safely, it was not without risk; foam was shed by the external tank, leading NASA to announce future missions would be grounded until this issue was resolved.

Between the Columbia disaster and the resumption of Shuttle launches, crew exchanges were carried out solely using the Russian Soyuz spacecraft. Starting with Expedition 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. However Progress transports and the STS-114 shuttle flight took care of this problem.

Changes in construction plans

Construction of the International Space Station over New Zealand.

ISS construction is now far behind the original planned schedule for completion in 2004 or 2005. This is mainly due to the halting of all NASA Shuttle flights following the Columbia disaster in early 2003 (although there had been prior delays due partly to Shuttle problems, and partly to delays stemming from the Russian space agency's budget constraints). 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.

As of the beginning of 2006, many changes were made to the originally planned ISS, even before the Columbia 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 part of the ISS's ultimate configuration.

In March 2006, a meeting of the heads of the five participating space agencies accepted the new ISS construction schedule that plans to complete the ISS by 2010.^[3] A crew of six has been established as of May 2009, following 12 Shuttle construction flights after the second "Return to Flight" mission STS-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.

Assembly sequence

ISS elements as of May 2011^[update]

The ISS consists of 15 pressurized modules: seven US modules (Destiny, Unity, Quest, Tranquility, Harmony, Cupola, and Leonardo), five Russian modules (Zarya, Zvezda, Pirs, Poisk and Rassvet), two Japanese modules (the JEM-ELM-PS and JEM-PM) and one European module (Columbus). One more Russian pressurized module (Nauka) is scheduled to be added to the station.

Although not permanently docked with the ISS, Multi-Purpose Logistics Modules (MPLMs) form part of the ISS during some Shuttle missions. An MPLM is attached to Harmony (initially to Unity) and is used for resupply and logistics flights.

Spacecraft docked 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.

The table below shows the sequence in which these components were or will be added to the ISS. The numbers provided are indications and represent launch weight and dimensions.

Element	Assembly flight	Launch date	Launch vehicle	Length (m)	Diameter (m)	Mass (kg)	Isolated View	Station View
Zarya (FGB)[4]	1A/R	1998-11-20	Proton-K	12.6	4.1	19,323
Unity (Node 1),[5] PMA-1 & PMA-2	2A	1998-12-04	Space Shuttle Endeavour (STS-88)	5.49	4.57	11,612
Zvezda (Service Module)[6]	1R	2000-07-12	Proton-K	13.1	4.15	19,051
Z1 Truss & PMA-3	3A	2000-10-11	Space Shuttle Discovery (STS-92)	4.9 (Z1)	4.2 (Z1)	8,755 (Z1)
P6 Truss & Solar Arrays	4A	2000-11-30	Space Shuttle Endeavour (STS-97)	73.2	4,9	15,824
Destiny (US Laboratory)[7]	5A	2001-02-07	Space Shuttle Atlantis (STS-98)	8.53	4.27	14,515
External Stowage Platform-1	5A.1	2001-03-08	Space Shuttle Discovery (STS-102)
Canadarm2 (SSRMS)	6A	2001-04-19	Space Shuttle Endeavour (STS-100)	17.6	0.35	4,899
Quest (Joint Airlock)[8]	7A	2001-07-12	Space Shuttle Atlantis (STS-104)	5.5	4	6,064
Pirs (Docking Compartment & Airlock)	4R	2001-09-14	Soyuz-U (Progress M-SO1)	4.91	2.55	3,580
S0 Truss[9]	8A	2002-04-08	Space Shuttle Atlantis (STS-110)	13.4	4.6	13,970
Mobile Base System	UF2	2002-06-05	Space Shuttle Endeavour (STS-111)	5.7	2.9	1,450
S1 Truss	9A	2002-10-07	Space Shuttle Atlantis (STS-112)	13.7	4.6	14,120
P1 Truss	11A	2002-11-23	Space Shuttle Endeavour (STS-113)	13.7	4.6	14,000
ESP-2	LF1	2005-07-26	Space Shuttle Discovery (STS-114)	3.65	4.9	2,676
P3/P4 Truss & Solar Arrays[10]	12A	2006-09-09	Space Shuttle Atlantis (STS-115)	13.8	4.9	15,900
P5 Truss[11]	12A.1	2006-12-09	Space Shuttle Discovery (STS-116)	3.4	4.6	1,818
S3/S4 Truss & Solar Arrays	13A	2007-06-08	Space Shuttle Atlantis (STS-117)	13.8	4.9	15,900
S5 Truss and ESP-3	13A.1	2007-08-08	Space Shuttle Endeavour (STS-118)	13.7	3.9	12,598
Harmony (Node 2) Relocation of P6 Truss	10A	2007-10-23	Space Shuttle Discovery (STS-120)	7.2	4.48	14,288
Columbus (European Laboratory)[12]	1E	2008-02-07	Space Shuttle Atlantis (STS-122)	7	4.5	12,800
Dextre (SPDM) Japanese Logistics Module (ELM-PS)	1J/A	2008-03-11	Space Shuttle Endeavour (STS-123)	3.9 (ELM-PS)	4.4 (ELM-PS)	4,200 (ELM-PS)
Japanese Pressurized Module (JEM-PM) JEM Robotic Arm (JEM-RMS)[13][14]	1J	2008-05-31	Space Shuttle Discovery (STS-124)	11.2 (JEM-PM)	4.4 (JEM-PM)	15,900 (JEM-PM)
S6 Truss & Solar Arrays	15A	2009-03-15	Space Shuttle Discovery (STS-119)	73.2	10.7	15,900
Japanese Exposed Facility (JEM-EF)	2J/A	2009-07-15	Space Shuttle Endeavour (STS-127)			4,100
Poisk (MRM-2)[15][16]	5R	2009-11-10	Soyuz-U (Progress M-MIM2)			3670
ExPRESS Logistics Carriers 1 & 2	ULF3	2009-11-16	Space Shuttle Atlantis (STS-129)
Cupola & Tranquility (Node 3)	20A	2010-02-08	Space Shuttle Endeavour (STS-130)	6.5 (Node 3) 1.5 (Cupola)	4.25 (Node 3) 2.95 (Cupola)	12,247 (Node 3) 1,800 (Cupola)
Rassvet (MRM-1)[17]	ULF4	2010-05-14	Space Shuttle Atlantis (STS-132)			5075
Leonardo (PMM) and EXPRESS Logistics Carrier 4	ULF5	2011-02-24	Space Shuttle Discovery (STS-133)
Alpha Magnetic Spectrometer, OBSS and EXPRESS Logistics Carrier 3	ULF6	2011-05-16	Space Shuttle Endeavour (STS-134)			6,731 (AMS-02)
Nauka (MLM) European Robotic Arm[18]	3R	2012-05-?? (scheduled)	Proton-M

Cancelled modules

• Interim Control Module - not needed once Zvezda was launched (in storage ready to launch at short notice if required)
• ISS Propulsion Module - not needed once Zvezda was launched
• Habitation Module (HAB) - With the cancellation of the Habitation Module, sleeping places are now spread throughout the station. There are two in the Russian segment and four in the US segment. It is not necessary to have a separate 'bunk' in space — many visitors just strap their sleeping bag to the wall of a module, get into it and sleep.
• Crew Return Vehicle (CRV) - replaced by two Soyuz crafts
• Centrifuge Accommodations Module (CAM) - would have been attached to Harmony (Node 2)
• Science Power Platform (SPP) - power will be provided to the Russian segments partly by the US solar cell platforms
• Russian Research Modules (RM1 and RM2) - to be replaced by single Multipurpose Laboratory Module (Nauka)
• Universal Docking Module (UDM) - canceled along with the Research Modules which were to connect to it

Proposed modules

The following modules are proposed, but not yet confirmed in the ISS launch manifests.

• Russian Nodal Module - UDM with proposed launch in 2013 ^[19][20]
• Russian Science-Power Module-1 - combination of RM1 and parts of SPP with proposed launch in 2014 ^[19][20]
• Russian Science-Power Module-2 - combination of RM2 and parts of SPP with proposed launch in 2015 ^[19][20]
• American Node 4 - Also known as the Docking Hub System (DHS),^[21] would allow the station to have more docking ports for visiting vehicles and would allow inflatable habitats and technology demonstrations to be tested as part of the station.^[22]
• Bigelow Aerospace inflatable module - Also known as the Bigelow Expandable Activity Module, or BEAM, for the ISS.^[23] Proposed for post-2013 launched atop an Expendable Launch Vehicle. The Bigelow inflatable module would be berthed to Node 3 or the currently unfunded Node 4.^[24][25]
• Nautilus-X Centrifuge Demonstration - If produced, this centrifuge will be the first in-space demonstration of sufficient scale centrifuge for artificial partial-g effects. It will be designed to become a sleep module for the ISS crew.^[26]

Formerly proposed and later abandoned modules:

• Russian Commercial Enterprise Module entertainment and studio module.^[27]

• 

  Inflatable module attached to Node 4

• 

  Nautilus-X ISS demonstrator

See also

For the full list of ISS flights see the List of unmanned spaceflights to the ISS and List of human spaceflights to the ISS

External links

• Animated ISS assembly process, mission designations and dates are included.
• Diagram of planned components of the ISS, positions of cancelled modules can be seen.

Media articles

• How It Works magazine - ISS nears completion

References

1. ^ "Consolidated Launch Manifest". NASA. http://www.nasa.gov/mission_pages/station/structure/iss_manifest.html. Retrieved 2006-07-15. 
2. ^ "What are the ISS attitudes?" (Flash). NASA. http://spaceflight.nasa.gov/station/flash/iss_attitude.html. Retrieved 2006-09-11. 
3. ^ Coppinger, Rob (3 March 2006). "NASA commits to Shuttle missions to International Space Station". FlightGlobal. http://www.flightglobal.com/articles/2006/03/03/205237/nasa-commits-to-shuttle-missions-to-international-space.html. Retrieved 16 September 2006. 
4. ^ Wade, Mark (15 July 2008). "ISS Zarya". Encyclopaedia Astronautica. http://www.astronautix.com/craft/isszarya.htm. Retrieved 2009-03-11. 
5. ^ "Unity Connecting Module: Cornerstone for a Home in Orbit" (PDF). NASA. January 1999. http://spaceflight.nasa.gov/spacenews/factsheets/pdfs/unity.pdf. Retrieved 2009-03-11. 
6. ^ "Zvezda Service Module". NASA. 11 March 2009. http://www.nasa.gov/mission_pages/station/structure/elements/sm.html. Retrieved 2009-03-11. 
7. ^ "US Destiny Laboratory". NASA. 26 March 2007. http://www.nasa.gov/mission_pages/station/structure/elements/destiny.html. Retrieved 2007-06-26. 
8. ^ "Space Station Extravehicular Activity". NASA. 4 April 2004. http://spaceflight.nasa.gov/station/eva/outside.html. Retrieved 2009-03-11. 
9. ^ "Space Station Assembly: Integrated Truss Structure". NASA. http://www.nasa.gov/mission_pages/station/structure/elements/its.html. Retrieved 2007-12-02. 
10. ^ "P3 and P4 to expand station capabilities, providing a third and fourth solar array" (pdf). Boeing. July 2006. http://www.boeing.com/defense-space/space/spacestation/components/docs/P3-P4.pdf. Retrieved 2007-12-02. 
11. ^ "STS-118 MISSION OVERVIEW: BUILD THE STATION…BUILD THE FUTURE" (PDF). NASA PAO. July 2007. http://www.nasa.gov/pdf/182728main_STS-118_Press_Kit.pdf. Retrieved 2007-12-02. 
12. ^ "Columbus laboratory". ESA. 10 January 2009. http://www.esa.int/esaHS/ESAAYI0VMOC_iss_0.html. Retrieved 2009-03-06. 
13. ^ "About Kibo". JAXA. 25 September 2008. http://kibo.jaxa.jp/en/about/. Retrieved 2009-03-06. 
14. ^ "Kibo Japanese Experiment Module". NASA. 23 November 2007. http://www.nasa.gov/mission_pages/station/structure/elements/jem.html. Retrieved 2008-11-22. 
15. ^ Zak, Anatoly. "Docking Compartment-1 and 2". RussianSpaceWeb.com. http://www.russianspaceweb.com/iss_dc.html. Retrieved 26 March 2009. 
16. ^ Bergin, Chris (9 November 2009). "Russian module launches via Soyuz for Thursday ISS docking". NASASpaceflight.com. http://www.nasaspaceflight.com/2009/11/live-russian-module-launch-towards-iss-on-soyuz/. Retrieved 10 November 2009. 
17. ^ "NASA Extends Contract With Russia’s Federal Space Agency" (Press release). NASA. 9 April 2007. http://www.nasa.gov/home/hqnews/2007/apr/HQ_C07-18_Roscosmos.html. Retrieved 2007-06-15. 
18. ^ "FGB-based Multipurpose Lab Module (MLM)". Khrunichev State Research and Production Space Centre. Archived from the original on 2007-09-27. http://web.archive.org/web/20070927002737/http://www.khrunichev.ru/khrunichev_eng/live/full_mks.asp?id=13190. Retrieved 2008-10-31. 
19. ^ ^{a b c} "Russia Needs Billions More To Complete It's ISS Segment". RIA Novosti via Space-Travel.com. 14 April 2008. http://www.space-travel.com/reports/Russia_Needs_Billions_More_To_Complete_Its_ISS_Segment_999.html. Retrieved 2009-01-29. 
20. ^ ^{a b c} Sergei Shamsutdinov (July 2008). "Program for Development of the Russian ISS Segment" (in Russian). Novosti Kosmonavtiki. http://www.novosti-kosmonavtiki.ru/content/numbers/306/index.shtml. Retrieved 2009-02-15. 
21. ^ http://www.nasaspaceflight.com/2010/12/iss-managers-long-term-configuration-international-space-station/
22. ^ Test article could facilitate space station applications - August 31st, 2010
23. ^ http://www.space.com/10686-nasa-bigelow-module-international-space-station.html
24. ^ http://www.nasaspaceflight.com/2011/01/nasa-managers-discuss-prospect-bigelow-inflatable-iss/
25. ^ "A New Space Enterprise of Exploration: Inflatable Module Mission". NASA. 2010-05-26. http://www.nasa.gov/pdf/458816main_FTD_InflatableModuleMission.pdf. Retrieved 11 May 2011. 
26. ^ http://www.scribd.com/doc/51592987/Nautilus-X-Holderman-1-26-11
27. ^ Zak, Anatoly. "Russian segment of the ISS". russianspaceweb.com. http://www.russianspaceweb.com/iss_russia.html. Retrieved 3 October 2009.