The process of assembling the International Space Station (ISS) has been under way since the 1990s. Zarya, the first ISS module, was launched by a Proton rocket on 20 November 1998. The STS-88 Space 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 uncrewed for the next one and a half years, until in July 2000 the Russian module Zvezda 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 1000 m3, a mass of approximately 410000 kg, approximately 100 kilowatts of power output, a truss 108.4 m long, modules 74 m 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 the Falcon 9, Russian Proton rocket or, in the case of Pirs and Poisk, the Soyuz-U rocket.
Some of the larger modules include:
- Zarya (launched 20 November 1998)
- Unity Module (launched 4 December 1998, also known as Node 1)
- Zvezda (launched 12 July 2000)
- Destiny Laboratory Module (launched 7 February 2001)
- Harmony Module (launched 23 October 2007, also known as Node 2)
- Columbus orbital facility (launched 7 February 2008)
- Japanese Experiment Module, also known as Kibō (launched in multiple flights between 2008 and 2009)
- The truss, original and iROSA solar panels (unpressurized, truss and original panels launched in multiple flights between 2000 and 2009, iROSAs launched between 2021 and 2023, a final set of iROSAs are planned to be sent in 2025)
- Nauka (MLM-U) (launched 21 July 2021)
Logistics
The space station is located in orbit around the Earth at an altitude of approximately 410 km, 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 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), the Quest and Pirs airlocks, as well as periodically the H-II Transfer Vehicle).
The US Orbital Segment was completed in 2011 after the installation of the Alpha Magnetic Spectrometer during the STS-134 mission. The Russian Orbital Segment assembly has been on an indefinite hiatus since the installation of the Rassvet module in 2010 during the STS-132 mission. The Rassvet module on the ISS right now was originally supposed to be the on-ground dynamic testing mock-up of the now-cancelled Science Power Platform. The Nauka science laboratory module contains new crew quarters, life support equipment that can produce oxygen and water, and a new galley.
Columbia disaster and changes in construction plans
Disaster and consequences
After the Space Shuttle Columbia 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.
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 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
Assembly sequence
The ISS is made up of 16 pressurized modules: six Russian modules (Zarya, Zvezda, Poisk, Rassvet, Nauka, and Prichal), eight US modules (BEAM,[9] Leonardo, Harmony, Quest, Tranquility, Unity, Cupola, and Destiny), 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 to Harmony (initially to Unity) and was used for resupply and logistics flights.
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.
Future elements
- In January 2021, NASA announced plans to upgrade the station's solar arrays by installing new arrays on top of all the station's eight existing arrays.[27] Six were delivered in three pairs, each pair aboard SpaceX CRS-22 in June 2021, SpaceX CRS-26 in November 2022 and SpaceX CRS-28 in June 2023.[28] Two more will be delivered in one pair aboard a future mission in 2025.[29]
- Axiom Space plans to launch one module, the Payload Power Thermal Module (PPTM), to the ISS to inaugurate its commercial Axiom Station project.[30]
Cancelled modules
- Interim Control Module – not needed once Zvezda was launched
- 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 crewed spacecraft docked to the station at all times (Soyuz, SpaceX Dragon 2)
- Centrifuge Accommodations Module (CAM) – would have been attached to Harmony (Node 2)
- Nautilus-X Centrifuge Demonstration – If produced, this centrifuge would have been the first in-space demonstration of sufficient scale centrifuge for artificial partial-g effects. It was designed to become a sleep module for the ISS crew.[31]
- Science Power Platform
Unused modules
The following module was built, but has not been used in future plans for the ISS as of January 2021.
Cost
The ISS 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]
See also
- List of human spaceflights to the International Space Station
- Uncrewed spaceflights to the International Space Station
- Manufacturing of the International Space Station
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
- 4 Astronauts Aboard SpaceX Crew Dragon Successfully Dock With Space Station www.npr.org, November 17, 2020, retrieved August 16, 2021^
- Consolidated Launch Manifest NASA, retrieved 2006-07-15^
- Новости. Подготовка "Науки" – идет четвёртый стартовый день