Фото Ивана Миско и Олега Новицкого на Международной космической станции. Photo by Ivan Misko and Oleg Novitskiy at the International Space Station.

The International Space Station (ISS) is a space station (habitable artificial satellite) in low Earth orbit. The ISS programme is a joint project between five participating space agencies: NASA (United States), Roscosmos (Russia), JAXA (Japan), ESA (Europe), and CSA (Canada).[6][7] The ownership and use of the space station is established by intergovernmental treaties and agreements.[8]

 

The ISS serves as a microgravity and space environment research laboratory in which crew members conduct experiments in biology, human biology, physics, astronomy, meteorology, and other fields.[9][10][11] The station is suited for the testing of spacecraft systems and equipment required for missions to the Moon and Mars.[12] The ISS maintains an orbit with an average altitude of 400 kilometres (250 mi) by means of reboost manoeuvres using the engines of the Zvezda module or visiting spacecraft.[13] It circles the Earth in roughly 92 minutes and completes 15.5 orbits per day.[14]

 

The station is divided into two sections, the Russian Orbital Segment (ROS), which is operated by Russia, and the United States Orbital Segment (USOS), which is shared by many nations. Roscosmos has endorsed the continued operation of ISS through 2024,[15] but had previously proposed using elements of the Russian segment to construct a new Russian space station called OPSEK.[16]As of December 2018, the station is expected to operate until 2030.[17]

 

The first ISS component was launched in 1998, with the first long-term residents arriving on 2 November 2000.[18] Since then, the station has been continuously occupied for 18 years and 359 days.[19] This is the longest continuous human presence in low Earth orbit, having surpassed the previous record of 9 years and 357 days held by Mir. The latest major pressurised module was fitted in 2011, with an experimental inflatable space habitat added in 2016. Development and assembly of the station continues, with several major new Russian elements scheduled for launch starting in 2020. The ISS is the largest human-made body in low Earth orbit and can often be seen with the naked eye from Earth.[20][21] The ISS consists of pressurised habitation modules, structural trusses, solar arrays, radiators, docking ports, experiment bays and robotic arms. Major ISS modules have been launched by Russian Proton and Soyuz rockets and US Space Shuttles.[22]

 

The ISS is the ninth space station to be inhabited by crews, following the Soviet and later Russian Salyut, Almaz, and Mir stations as well as Skylab from the US. The station is serviced by a variety of visiting spacecraft: the Russian Soyuz and Progress, the US Dragon and Cygnus, the Japanese H-II Transfer Vehicle,[6] and the European Automated Transfer Vehicle. The Dragon spacecraft allows the return of pressurised cargo to Earth (downmass), which is used for example to repatriate scientific experiments for further analysis. The Soyuz return capsule has minimal downmass capability next to the astronauts.

 

The ISS has been visited by astronauts, cosmonauts and space tourists from 18 different nations. As of 14 March 2019, 236 people from 18 countries had visited the space station, many of them multiple times. The United States sent 149 people, Russia sent 47, nine were Japanese, eight were Canadian, five were Italian, four were French, three were German, and there were one each from Belgium, Brazil, Denmark, Kazakhstan, Malaysia, the Netherlands, South Africa, United Arab Emirates, South Korea, Spain, Sweden, and the United Kingdom.[23]

Contents

 

1 Purpose

2 Manufacturing

3 Assembly

4 Structure

5 Systems

6 Operations

7 Mission controls

8 Fleet operations

9 Life aboard

10 Crew health and safety

11 Orbital debris threats

12 End of mission

13 Cost

14 International co-operation

15 Sightings from Earth

16 See also

17 Notes

18 References

19 Further reading

20 External links

 

Purpose

 

The ISS was originally intended to be a laboratory, observatory, and factory while providing transportation, maintenance, and a low Earth orbit staging base for possible future missions to the Moon, Mars, and asteroids. However, not all of the uses envisioned in the initial Memorandum of Understanding between NASA and Roskosmos have come to fruition.[24] In the 2010 United States National Space Policy, the ISS was given additional roles of serving commercial, diplomatic[25] and educational purposes.[26]

Scientific research

Main article: Scientific research on the International Space Station

Comet Lovejoy photographed by Expedition 30 commander Dan Burbank

Expedition 8 Commander and Science Officer Michael Foale conducts an inspection of the Microgravity Science Glovebox

Fisheye view of several labs

CubeSats are deployed by the NanoRacks CubeSat Deployer

 

The ISS provides a platform to conduct scientific research, with power, data, cooling, and crew available to support experiments. Small uncrewed spacecraft can also provide platforms for experiments, especially those involving zero gravity and exposure to space, but space stations offer a long-term environment where studies can be performed potentially for decades, combined with ready access by human researchers.[27][28]

 

The ISS simplifies individual experiments by allowing groups of experiments to share the same launches and crew time. Research is conducted in a wide variety of fields, including astrobiology, astronomy, physical sciences, materials science, space weather, meteorology, and human research including space medicine and the life sciences.[9][10][11][29][30] Scientists on Earth have timely access to the data and can suggest experimental modifications to the crew. If follow-on experiments are necessary, the routinely scheduled launches of resupply craft allows new hardware to be launched with relative ease.[28] Crews fly expeditions of several months' duration, providing approximately 160 person-hours per week of labour with a crew of 6. However, a considerable amount of crew time is taken up by station maintenance.[9][31]

 

Perhaps the most notable ISS experiment is the Alpha Magnetic Spectrometer (AMS), which is intended to detect dark matter and answer other fundamental questions about our universe and is as important as the Hubble Space Telescope according to NASA. Currently docked on station, it could not have been easily accommodated on a free flying satellite platform because of its power and bandwidth needs.[32][33] On 3 April 2013, scientists reported that hints of dark matter may have been detected by the AMS.[34][35][36][37][38][39] According to the scientists, "The first results from the space-borne Alpha Magnetic Spectrometer confirm an unexplained excess of high-energy positrons in Earth-bound cosmic rays."

 

The space environment is hostile to life. Unprotected presence in space is characterised by an intense radiation field (consisting primarily of protons and other subatomic charged particles from the solar wind, in addition to cosmic rays), high vacuum, extreme temperatures, and microgravity.[40] Some simple forms of life called extremophiles,[41] as well as small invertebrates called tardigrades[42] can survive in this environment in an extremely dry state through desiccation.

 

Medical research improves knowledge about the effects of long-term space exposure on the human body, including muscle atrophy, bone loss, and fluid shift. This data will be used to determine whether high duration human spaceflight and space colonisation are feasible. As of 2006, data on bone loss and muscular atrophy suggest that there would be a significant risk of fractures and movement problems if astronauts landed on a planet after a lengthy interplanetary cruise, such as the six-month interval required to travel to Mars.[43][44]

 

Medical studies are conducted aboard the ISS on behalf of the National Space Biomedical Research Institute (NSBRI). Prominent among these is the Advanced Diagnostic Ultrasound in Microgravity study in which astronauts perform ultrasound scans under the guidance of remote experts. The study considers the diagnosis and treatment of medical conditions in space. Usually, there is no physician on board the ISS and diagnosis of medical conditions is a challenge. It is anticipated that remotely guided ultrasound scans will have application on Earth in emergency and rural care situations where access to a trained physician is difficult.[45][46][47]

Free fall

ISS crew member storing samples

A comparison between the combustion of a candle on Earth (left) and in a free fall environment, such as that found on the ISS (right)

 

Gravity at the altitude of the ISS is approximately 90% as strong as at Earth's surface, but objects in orbit are in a continuous state of freefall, resulting in an apparent state of weightlessness.[48] This perceived weightlessness is disturbed by five separate effects:[49]

 

Drag from the residual atmosphere.

Vibration from the movements of mechanical systems and the crew.

Actuation of the on-board attitude control moment gyroscopes.

Thruster firings for attitude or orbital changes.

Gravity-gradient effects, also known as tidal effects. Items at different locations within the ISS would, if not attached to the station, follow slightly different orbits. Being mechanically interconnected these items experience small forces that keep the station moving as a rigid body.

 

Researchers are investigating the effect of the station's near-weightless environment on the evolution, development, growth and internal processes of plants and animals. In response to some of this data, NASA wants to investigate microgravity's effects on the growth of three-dimensional, human-like tissues, and the unusual protein crystals that can be formed in space.[10]

 

Investigating the physics of fluids in microgravity will provide better models of the behaviour of fluids. Because fluids can be almost completely combined in microgravity, physicists investigate fluids that do not mix well on Earth. In addition, examining reactions that are slowed by low gravity and low temperatures will improve our understanding of superconductivity.[10]

 

The study of materials science is an important ISS research activity, with the objective of reaping economic benefits through the improvement of techniques used on the ground.[50] Other areas of interest include the effect of the low gravity environment on combustion, through the study of the efficiency of burning and control of emissions and pollutants. These findings may improve current knowledge about energy production, and lead to economic and environmental benefits. Future plans are for the researchers aboard the ISS to examine aerosols, ozone, water vapour, and oxides in Earth's atmosphere, as well as cosmic rays, cosmic dust, antimatter, and dark matter in the universe.[10]

Exploration

A 3D plan of the Russia-based MARS-500 complex, used for ground-based experiments which complement ISS-based preparations for a human mission to Mars

 

The ISS provides a location in the relative safety of Low Earth Orbit to test spacecraft systems that will be required for long-duration missions to the Moon and Mars. This provides experience in operations, maintenance as well as repair and replacement activities on-orbit, which will be essential skills in operating spacecraft farther from Earth, mission risks can be reduced and the capabilities of interplanetary spacecraft advanced.[12] Referring to the MARS-500 experiment, ESA states that "Whereas the ISS is essential for answering questions concerning the possible impact of weightlessness, radiation and other space-specific factors, aspects such as the effect of long-term isolation and confinement can be more appropriately addressed via ground-based simulations".[51] Sergey Krasnov, the head of human space flight programmes for Russia's space agency, Roscosmos, in 2011 suggested a "shorter version" of MARS-500 may be carried out on the ISS.[52]

 

In 2009, noting the value of the partnership framework itself, Sergey Krasnov wrote, "When compared with partners acting separately, partners developing complementary abilities and resources could give us much more assurance of the success and safety of space exploration. The ISS is helping further advance near-Earth space exploration and realisation of prospective programmes of research and exploration of the Solar system, including the Moon and Mars."[53] A crewed mission to Mars may be a multinational effort involving space agencies and countries outside the current ISS partnership. In 2010, ESA Director-General Jean-Jacques Dordain stated his agency was ready to propose to the other four partners that China, India and South Korea be invited to join the ISS partnership.[54] NASA chief Charlie Bolden stated in February 2011, "Any mission to Mars is likely to be a global effort".[55] Currently, US federal legislation prevents NASA co-operation with China on space projects.[56]

Education and cultural outreach

Original Jules Verne manuscripts displayed by crew inside Jules Verne ATV

 

The ISS crew provides opportunities for students on Earth by running student-developed experiments, making educational demonstrations, allowing for student participation in classroom versions of ISS experiments, and directly engaging students using radio, videolink and email.[6][57] ESA offers a wide range of free teaching materials that can be downloaded for use in classrooms.[58] In one lesson, students can navigate a 3-D model of the interior and exterior of the ISS, and face spontaneous challenges to solve in real time.[59]

 

JAXA aims to inspire children to "pursue craftsmanship" and to heighten their "awareness of the importance of life and their responsibilities in society."[60] Through a series of education guides, a deeper understanding of the past and near-term future of crewed space flight, as well as that of Earth and life, will be learned.[61][62] In the JAXA Seeds in Space experiments, the mutation effects of spaceflight on plant seeds aboard the ISS is explored. Students grow sunflower seeds which flew on the ISS for about nine months. In the first phase of Kibō utilisation from 2008 to mid-2010, researchers from more than a dozen Japanese universities conducted experiments in diverse fields.[63]

Menu

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ESA Astronaut Paolo Nespoli's spoken voice, recorded about the ISS in November 2017, for Wikipedia

 

Cultural activities are another major objective. Tetsuo Tanaka, director of JAXA's Space Environment and Utilization Center, says "There is something about space that touches even people who are not interested in science."[64]

 

Amateur Radio on the ISS (ARISS) is a volunteer programme which encourages students worldwide to pursue careers in science, technology, engineering and mathematics through amateur radio communications opportunities with the ISS crew. ARISS is an international working group, consisting of delegations from nine countries including several countries in Europe as well as Japan, Russia, Canada, and the United States. In areas where radio equipment cannot be used, speakerphones connect students to ground stations which then connect the calls to the station.[65]

 

First Orbit is a feature-length documentary film about Vostok 1, the first crewed space flight around the Earth. By matching the orbit of the International Space Station to that of Vostok 1 as closely as possible, in terms of ground path and time of day, documentary filmmaker Christopher Riley and ESA astronaut Paolo Nespoli were able to film the view that Yuri Gagarin saw on his pioneering orbital space flight. This new footage was cut together with the original Vostok 1 mission audio recordings sourced from the Russian State Archive. Nespoli, during Expedition 26/27, filmed the majority of the footage for this documentary film, and as a result is credited as its director of photography.[66] The film was streamed through the website firstorbit.org in a global YouTube premiere in 2011, under a free licence.[67]

 

In May 2013, commander Chris Hadfield shot a music video of David Bowie's "Space Oddity" on board the station; the film was released on YouTube.[68] It was the first music video ever to be filmed in space.[69]

 

In November 2017, while participating in Expedition 52/53 on the ISS, Paolo Nespoli made two recordings (one in English the other in his native Italian) of his spoken voice, for use on Wikipedia articles. These were the first content made specifically for Wikipedia, in space.[70][71]

Manufacturing

Main article: Manufacturing of the International Space Station

ISS module Node 2 manufacturing and processing in the SSPF

 

Since the International Space Station is a multi-national collaborative project, the components for in-orbit assembly were manufactured in various countries around the world. Beginning in the mid 1990s, the U.S. components Destiny, Unity, the Integrated Truss Structure, and the solar arrays were fabricated at the Marshall Space Flight Center and the Michoud Assembly Facility. These modules were delivered to the Operations and Checkout Building and the Space Station Processing Facility for final assembly and processing for launch.[72]

 

The Russian modules, including Zarya and Zvezda, were manufactured at the Khrunichev State Research and Production Space Center in Moscow. Zvezda was initially manufactured in 1985 as a component for Mir-2, but was never launched and instead became the ISS Service Module.[73]

 

The European Space Agency Columbus module was manufactured at the European Space Research and Technology Centre (ESTEC) in the Netherlands, along with many other contractors throughout Europe.[74] The other ESA-built modules - Harmony, Tranquility, the Leonardo MPLM, and the Cupola - were initially manufactured at the Thales Alenia Space factory located at the Cannes Mandelieu Space Center. The structural steel hulls of the modules were transported by aircraft to the Kennedy Space Center SSPF for launch processing.[75]

 

The Japanese Experiment Module Kibō, was fabricated in various technology manufacturing facilities in Japan, at the NASDA (now JAXA) Tanegashima Space Center, and the Institute of Space and Astronautical Science. The Kibo module was transported by ship and flown by aircraft to the KSC Space Station Processing Facility.[76]

 

The Mobile Servicing System, consisting of the Canadarm2 and the Dextre grapple fixture, was manufactured at various factories in Canada and the United States under contract by the Canadian Space Agency. The mobile base system, a connecting framework for Canadarm2 mounted on rails, was built by Northrop Grumman.

Assembly

Main articles: Assembly of the International Space Station and List of ISS spacewalks

 

The assembly of the International Space Station, a major endeavour in space architecture, began in November 1998.[3] Russian modules launched and docked robotically, with the exception of Rassvet. All other modules were delivered by the Space Shuttle, which required installation by ISS and shuttle crewmembers using the Canadarm2 (SSRMS) and extra-vehicular activities (EVAs); as of 5 June 2011, they had added 159 components during more than 1,000 hours of EVA (see List of ISS spacewalks). 127 of these spacewalks originated from the station, and the remaining 32 were launched from the airlocks of docked Space Shuttles.[77] The beta angle of the station had to be considered at all times during construction.[78]

 

The first module of the ISS, Zarya, was launched on 20 November 1998 on an autonomous Russian Proton rocket. It provided propulsion, attitude control, communications, electrical power, but lacked long-term life support functions. Two weeks later, a passive NASA module Unity was launched aboard Space Shuttle flight STS-88 and attached to Zarya by astronauts during EVAs. This module has two Pressurised Mating Adapter (PMAs), one connects permanently to Zarya, the other allowed the Space Shuttle to dock to the space station. At that time, the Russian station Mir was still inhabited, and the ISS remained uncrewed for two years. On 12 July 2000, Zvezda was launched into orbit. Preprogrammed commands on board deployed its solar arrays and communications antenna. It then became the passive target for a rendezvous with Zarya and Unity: it maintained a station-keeping orbit while the Zarya-Unity vehicle performed the rendezvous and docking via ground control and the Russian automated rendezvous and docking system. Zarya's computer transferred control of the station to Zvezda's computer soon after docking. Zvezda added sleeping quarters, a toilet, kitchen, CO2 scrubbers, dehumidifier, oxygen generators, exercise equipment, plus data, voice and television communications with mission control. This enabled permanent habitation of the station.[79][80]

 

The first resident crew, Expedition 1, arrived in November 2000 on Soyuz TM-31. At the end of the first day on the station, astronaut Bill Shepherd requested the use of the radio call sign "Alpha", which he and cosmonaut Krikalev preferred to the more cumbersome "International Space Station".[81] The name "Alpha" had previously been used for the station in the early 1990s,[82] and its use was authorised for the whole of Expedition 1.[83] Shepherd had been advocating the use of a new name to project managers for some time. Referencing a naval tradition in a pre-launch news conference he had said: "For thousands of years, humans have been going to sea in ships. People have designed and built these vessels, launched them with a good feeling that a name will bring good fortune to the crew and success to their voyage."[84] Yuri Semenov, the President of Russian Space Corporation Energia at the time, disapproved of the name "Alpha" as he felt that Mir was the first modular space station, so the names "Beta" or "Mir 2" for the ISS would have been more fitting.[83][85][86]

 

Expedition 1 arrived midway between the flights of STS-92 and STS-97. These two Space Shuttle flights each added segments of the station's Integrated Truss Structure, which provided the station with Ku-band communication for US television, additional attitude support needed for the additional mass of the USOS, and substantial solar arrays supplementing the station's existing 4 solar arrays.[87]

 

Over the next two year, the station continued to expand. A Soyuz-U rocket delivered the Pirs docking compartment. The Space Shuttles Discovery, Atlantis, and Endeavour delivered the Destiny laboratory and Quest airlock, in addition to the station's main robot arm, the Canadarm2, and several more segments of the Integrated Truss Structure.

 

The expansion schedule was interrupted by the Space Shuttle Columbia disaster in 2003 and a resulting hiatus in flights. The Space Shuttle was grounded until 2005 with STS-114 flown by Discovery.[88]

 

Assembly resumed in 2006 with the arrival of STS-115 with Atlantis, which delivered the station's second set of solar arrays. Several more truss segments and a third set of arrays were delivered on STS-116, STS-117, and STS-118. As a result of the major expansion of the station's power-generating capabilities, more pressurised modules could be accommodated, and the Harmony node and Columbus European laboratory were added. These were soon followed by the first two components of Kibō. In March 2009, STS-119 completed the Integrated Truss Structure with the installation of the fourth and final set of solar arrays. The final section of Kibō was delivered in July 2009 on STS-127, followed by the Russian Poisk module. The third node, Tranquility, was delivered in February 2010 during STS-130 by the Space Shuttle Endeavour, alongside the Cupola, followed in May 2010 by the penultimate Russian module, Rassvet. Rassvet was delivered by Space Shuttle Atlantis on STS-132 in exchange for the Russian Proton delivery of the US-funded Zarya module in 1998.[89] The last pressurised module of the USOS, Leonardo, was brought to the station in February 2011 on the final flight of Discovery, STS-133.[90] The Alpha Magnetic Spectrometer was delivered by Endeavour on STS-134 the same year.[91]

 

As of June 2011, the station consisted of 15 pressurised modules and the Integrated Truss Structure. Five modules are still to be launched, including the Nauka with the European Robotic Arm, the Prichal module, and two power modules called NEM-1 and NEM-2.[92] As of March 2019, Russia's future primary research module Nauka is set to launch in the summer of 2020, along with the European Robotic Arm which will be able to relocate itself to different parts of the Russian modules of the station.[93]

 

The gross mass of the station changes over time. The total launch mass of the modules on orbit is about 417,289 kg (919,965 lb) (as of 3 September 2011).[94] The mass of experiments, spare parts, personal effects, crew, foodstuff, clothing, propellants, water supplies, gas supplies, docked spacecraft, and other items add to the total mass of the station. Hydrogen gas is constantly vented overboard by the oxygen generators.

 

The ISS is a third generation[95] modular space station.[96] Modular stations can allow modules to be added to or removed from the existing structure, allowing greater flexibility.

 

Below is a diagram of major station components. The blue areas are pressurised sections accessible by the crew without using spacesuits. The station's unpressurised superstructure is indicated in red. Other unpressurised components are yellow. The Unity node joins directly to the Destiny laboratory. For clarity, they are shown apart.

 

Zarya

Zarya as seen by Space Shuttle Endeavour during STS-88

 

Zarya (Russian: Заря́, lit. 'Dawn'), also known as the Functional Cargo Block or FGB (from the Russian: "Функционально-грузовой блок", lit. 'Funktsionalno-gruzovoy blok' or ФГБ), is the first module of the ISS to be launched.[97] The FGB provided electrical power, storage, propulsion, and guidance to the ISS during the initial stage of assembly. With the launch and assembly in orbit of other modules with more specialized functionality, Zarya is now[when?] primarily used for storage, both inside the pressurized section and in the externally mounted fuel tanks. The Zarya is a descendant of the TKS spacecraft designed for the Russian Salyut program. The name Zarya, which means sunrise,[97] was given to the FGB because it signified the dawn of a new era of international cooperation in space. Although it was built by a Russian company, it is owned by the United States.[98]

 

Zarya was built from December 1994 to January 1998 at the Khrunichev State Research and Production Space Center (KhSC) in Moscow.[97]

 

Zarya was launched on 20 November 1998 on a Russian Proton rocket from Baikonur Cosmodrome Site 81 in Kazakhstan to a 400 km (250 mi) high orbit with a designed lifetime of at least 15 years. After Zarya reached orbit, STS-88 launched on 4 December 1998 to attach the Unity module.

Unity

Unity as seen by Space Shuttle Endeavour during STS-88

Main article: Unity (ISS module)

 

The Unity connecting module, also known as Node 1, is the first U.S.-built component of the ISS. It connects the Russian and United States segments of the station, and is where crew eat meals together.

 

The module is cylindrical in shape, with six berthing locations (forward, aft, port, starboard, zenith, and nadir) facilitating connections to other modules. Unity measures 4.57 metres (15.0 ft) in diameter, is 5.47 metres (17.9 ft) long, made of steel, and was built for NASA by Boeing in a manufacturing facility at the Marshall Space Flight Center in Huntsville, Alabama. Unity is the first of the three connecting modules; the other two are Harmony and Tranquility.

 

Unity was carried into orbit as the primary cargo of the Space Shuttle Endeavour on STS-88, the first Space Shuttle mission dedicated to assembly of the station. On 6 December 1998, the STS-88 crew mated the aft berthing port of Unity with the forward hatch of the already orbiting Zarya module. This was the first connection made between two station modules.

Zvezda

Zvezda as seen by Space Shuttle Endeavour during STS-97

Main article: Zvezda (ISS module)

 

Zvezda (Russian: Звезда́, meaning "star"), Salyut DOS-8, also known as the Zvezda Service Module, is a module of the ISS. It was the third module launched to the station, and provides all of the station's life support systems, some of which are supplemented in the USOS, as well as living quarters for two crew members. It is the structural and functional center of the Russian Orbital Segment, which is the Russian part of the ISS. Crew assemble here to deal with emergencies on the station.[99][100][101]

 

The basic structural frame of Zvezda, known as "DOS-8", was initially built in the mid-1980s to be the core of the Mir-2 space station. This means that Zvezda is similar in layout to the core module (DOS-7) of the Mir space station. It was in fact labeled as Mir-2 for quite some time in the factory. Its design lineage thus extends back to the original Salyut stations. The space frame was completed in February 1985 and major internal equipment was installed by October 1986.

 

The rocket used for launch to the ISS carried advertising; it was emblazoned with the logo of Pizza Hut restaurants,[102][103][104] for which they are reported to have paid more than US$1 million.[105] The money helped support Khrunichev State Research and Production Space Center and the Russian advertising agencies that orchestrated the event.[106]

 

On 26 July 2000, Zvezda became the third component of the ISS when it docked at the aft port of Zarya. (U.S. Unity module had already been attached to the Zarya.) Later in July, the computers aboard Zarya handed over ISS commanding functions to computers on Zvezda.[107]

Destiny

The Destiny module being installed on the ISS

Main article: Destiny (ISS module)

 

The Destiny module, also known as the U.S. Lab, is the primary operating facility for U.S. research payloads aboard the International Space Station (ISS).[108][109] It was berthed to the Unity module and activated over a period of five days in February, 2001.[110] Destiny is NASA's first permanent operating orbital research station since Skylab was vacated in February 1974.

 

The Boeing Company began construction of the 14.5-tonne (32,000 lb) research laboratory in 1995 at the Michoud Assembly Facility and then the Marshall Space Flight Center in Huntsville, Alabama.[108] Destiny was shipped to the Kennedy Space Center in Florida in 1998, and was turned over to NASA for pre-launch preparations in August 2000. It launched on 7 February 2001 aboard the Space Shuttle Atlantis on STS-98.[110]

Quest

Quest Joint Airlock Module

Main article: Quest Joint Airlock

 

The Quest Joint Airlock, previously known as the Joint Airlock Module, is the primary airlock for the ISS. Quest was designed to host spacewalks with both Extravehicular Mobility Unit (EMU) spacesuits and Orlan space suits. The airlock was launched on STS-104 on 14 July 2001. Before Quest was attached, Russian spacewalks using Orlan suits could only be done from the Zvezda service module, and American spacewalks using EMUs were only possible when a Space Shuttle was docked. The arrival of Pirs docking compartment on September 16, 2001 provided another airlock from which Orlan spacewalks can be conducted.[citation needed]

Pirs and Poisk

The Pirs module attached to the ISS.

Poisk after arriving at the ISS on 12 November 2009.

Main articles: Pirs (ISS module) and Poisk (ISS module)

 

Pirs (Russian: Пирс, lit. 'pier') and Poisk (Russian: По́иск, lit. 'search') are Russian airlock modules, each having 2 identical hatches. An outward-opening hatch on the Mir space station failed after it swung open too fast after unlatching, because of a small amount of air pressure remaining in the airlock.[111] All EVA hatches on the ISS open inwards and are pressure-sealing. Pirs was used to store, service, and refurbish Russian Orlan suits and provided contingency entry for crew using the slightly bulkier American suits. The outermost docking ports on both airlocks allow docking of Soyuz and Progress spacecraft, and the automatic transfer of propellants to and from storage on the ROS.[112]

 

Pirs was launched on 14 September 2001, as ISS Assembly Mission 4R, on a Russian Soyuz-U rocket, using a modified Progress spacecraft, Progress M-SO1, as an upper stage. Poisk was launched on 10 November 2009[113][114] attached to a modified Progress spacecraft, called Progress M-MIM2, on a Soyuz-U rocket from Launch Pad 1 at the Baikonur Cosmodrome in Kazakhstan.

Harmony

Harmony shown connected to Columbus, Kibo, and Destiny. PMA-2 faces. The nadir and zenith locations are open.

Main article: Harmony (ISS module)

 

Harmony, also known as Node 2, is the "utility hub" of the ISS. It connects the laboratory modules of the United States, Europe and Japan, as well as providing electrical power and electronic data. Sleeping cabins for four of the six crew are housed here.[115]

 

Harmony was successfully launched into space aboard Space Shuttle flight STS-120 on October 23, 2007.[116][117] After temporarily being attached to the port side of the Unity node,[118][119] it was moved to its permanent location on the forward end of the Destiny laboratory on November 14, 2007.[120] Harmony added 2,666 cubic feet (75.5 m3) to the station's living volume, an increase of almost 20 percent, from 15,000 cu ft (420 m3) to 17,666 cu ft (500.2 m3). Its successful installation meant that from NASA's perspective, the station was "U.S. Core Complete".

Tranquility

Tranquility in 2011

Main article: Tranquility (ISS module)

 

Tranquility, also known as Node 3, is a module of the ISS. It contains environmental control systems, life support systems, a toilet, exercise equipment, and an observation cupola.

 

ESA and the Italian Space Agency had Tranquility built by Thales Alenia Space. A ceremony on November 20, 2009 transferred ownership of the module to NASA.[121] On February 8, 2010, NASA launched the module on the Space Shuttle's STS-130 mission.

Columbus

The Columbus module on the ISS

Main article: Columbus (ISS module)

 

Columbus is a science laboratory that is part of the ISS and is the largest single contribution to the ISS made by the European Space Agency (ESA).

 

Like the Harmony and Tranquility modules, the Columbus laboratory was constructed in Turin, Italy by Thales Alenia Space. The functional equipment and software of the lab was designed by EADS in Bremen, Germany. It was also integrated in Bremen before being flown to the Kennedy Space Center (KSC) in Florida in an Airbus Beluga. It was launched aboard Space Shuttle Atlantis on 7 February 2008 on flight STS-122. It is designed for ten years of operation. The module is controlled by the Columbus Control Centre, located at the German Space Operations Centre, part of the German Aerospace Center in Oberpfaffenhofen near Munich, Germany.

 

The European Space Agency has spent €1.4 billion (about US$2 billion) on building Columbus, including the experiments that will fly in it and the ground control infrastructure necessary to operate them.[122]

Kibō

Kibō Exposed Facility on the right

Main article: Kibo (ISS module)

 

The Japanese Experiment Module (JEM), nicknamed Kibo (きぼう Kibō, Hope), is a Japanese science module for the ISS developed by JAXA. It is the largest single ISS module, and is attached to the Harmony module. The first two pieces of the module were launched on Space Shuttle missions STS-123 and STS-124. The third and final components were launched on STS-127.[123]

 

Pressurised Module

 

Experiment Logistics Module

 

Exposed Facility

 

Experiment Logistics Module

 

Remote Manipulator System

 

Cupola

The Cupola's windows with shutters open.

Main article: Cupola (ISS module)

 

The Cupola is an ESA-built observatory module of the ISS. Its name derives from the Italian word cupola, which means "dome". Its seven windows are used to conduct experiments, dockings and observations of Earth. It was launched aboard Space Shuttle mission STS-130 on 8 February 2010 and attached to the Tranquility (Node 3) module. With the Cupola attached, ISS assembly reached 85 percent completion. The Cupola's central window has a diameter of 80 cm (31 in).[124]

Rassvet

Rassvet as seen from the Cupola module during STS-132 with a Progress in the lower right

Main article: Rassvet (ISS module)

 

Rassvet (Russian: Рассве́т; lit. "dawn"), also known as the Mini-Research Module 1 (MRM-1) (Russian: Малый исследовательский модуль, МИМ 1) and formerly known as the Docking Cargo Module (DCM), is a component of the ISS. The module's design is similar to the Mir Docking Module launched on STS-74 in 1995. Rassvet is primarily used for cargo storage and as a docking port for visiting spacecraft. It was flown to the ISS aboard Space Shuttle Atlantis on the STS-132 mission on May 14, 2010,[125] and was connected to the ISS on May 18.[126] The hatch connecting Rassvet with the ISS was first opened on May 20.[127] On 28 June 2010, the Soyuz TMA-19 spacecraft performed the first docking with the module.[128]

Leonardo

Leonardo Permanent Multipurpose Module

Main article: Leonardo (ISS module)

 

The Leonardo Permanent Multipurpose Module (PMM) is a module of the ISS. It was flown into space aboard the Space Shuttle on STS-133 on 24 February 2011 and installed on 1 March. Leonardo is primarily used for storage of spares, supplies and waste on the ISS, which was until then stored in many different places within the space station. The Leonardo PMM was a Multi-Purpose Logistics Module (MPLM) before 2011, but was modified into its current configuration. It was formerly one of three MPLM used for bringing cargo to and from the ISS with the Space Shuttle. The module was named for Italian polymath Leonardo da Vinci.

Bigelow Expandable Activity Module

Progression of expansion of BEAM

Main article: Bigelow Expandable Activity Module

 

The Bigelow Expandable Activity Module (BEAM) is an experimental expandable space station module developed by Bigelow Aerospace, under contract to NASA, for testing as a temporary module on the ISS from 2016 to at least 2020. It arrived at the ISS on 10 April 2016,[129] was berthed to the station on 16 April, and was expanded and pressurized on 28 May 2016.

International Docking Adapter

IDA-1 upright

Main article: International Docking Adapter

 

The International Docking Adapter (IDA) is a spacecraft docking system adapter developed to convert APAS-95 to the NASA Docking System (NDS)/International Docking System Standard (IDSS). An IDA is placed on each of the ISS' two open Pressurized Mating Adapters (PMAs), both of which are connected to the Harmony module.

 

IDA-1 was lost during the launch failure of SpaceX CRS-7 on 28 June 2015.[130][131][132]

 

IDA-2 was launched on SpaceX CRS-9 on 18 July 2016.[133] It was attached and connected to PMA-2 during a spacewalk on 19 August 2016.[134] First docking was achieved with the arrival of Crew Dragon Demo-1 on 3 March 2019. [135]

 

IDA-3 was launched on the SpaceX CRS-18 mission in July 2019.[136] IDA-3 is constructed mostly from spare parts to speed construction.[137] It was attached and connected to PMA-3 during a spacewalk on 21 August 2019. [138]

Unpressurised elements

ISS Truss Components breakdown showing Trusses and all ORUs in situ

 

The ISS has a large number of external components that do not require pressurisation. The largest of these is the Integrated Truss Structure (ITS), to which the station's main solar arrays and thermal radiators are mounted.[139] The ITS consists of ten separate segments forming a structure 108.5 m (356 ft) long.[3]

 

The station was intended to have several smaller external components, such as six robotic arms, three External Stowage Platforms (ESPs) and four ExPRESS Logistics Carriers (ELCs).[140][141] While these platforms allow experiments (including MISSE, the STP-H3 and the Robotic Refueling Mission) to be deployed and conducted in the vacuum of space by providing electricity and processing experimental data locally, their primary function is to store spare Orbital Replacement Units (ORUs). ORUs are parts that can be replaced when they fail or pass their design life, including pumps, storage tanks, antennas, and battery units. Such units are replaced either by astronauts during EVA or by robotic arms.[142] Several shuttle missions were dedicated to the delivery of ORUs, including STS-129,[143] STS-133[144] and STS-134.[145] As of January 2011, only one other mode of transportation of ORUs had been utilised – the Japanese cargo vessel HTV-2 – which delivered an FHRC and CTC-2 via its Exposed Pallet (EP).[146][needs update]

Construction of the Integrated Truss Structure over New Zealand.

 

There are also smaller exposure facilities mounted directly to laboratory modules; the Kibō Exposed Facility serves as an external 'porch' for the Kibō complex,[147] and a facility on the European Columbus laboratory provides power and data connections for experiments such as the European Technology Exposure Facility[148][149] and the Atomic Clock Ensemble in Space.[150] A remote sensing instrument, SAGE III-ISS, was delivered to the station in February 2017 aboard CRS-10,[151] and the NICER experiment was delivered aboard CRS-11 in June 2017.[152] The largest scientific payload externally mounted to the ISS is the Alpha Magnetic Spectrometer (AMS), a particle physics experiment launched on STS-134 in May 2011, and mounted externally on the ITS. The AMS measures cosmic rays to look for evidence of dark matter and antimatter.[153][154]

 

The commercial Bartolomeo External Payload Hosting Platform, manufactured by Airbus, is due to launch in May 2019 aboard a commercial ISS resupply vehicle and be attached to the European Columbus module. It will provide a further 12 external payload slots, supplementing the eight on the ExPRESS Logistics Carriers, ten on Kibō, and four on Columbus. The system is designed to be robotically serviced and will require no astronaut intervention. It is named after Christopher Columbus's younger brother.[155][156][157]

Robotic arms and cargo cranes

Commander Volkov stands on Pirs with his back to the Soyuz whilst operating the manual Strela crane holding photographer Kononenko.

Dextre, like many of the station's experiments and robotic arms, can be operated from Earth and perform tasks while the crew sleeps.

 

The Integrated Truss Structure serves as a base for the station's primary remote manipulator system, called the Mobile Servicing System (MSS), which is composed of three main components. Canadarm2, the largest robotic arm on the ISS, has a mass of 1,800 kilograms (4,000 lb) and is used to dock and manipulate spacecraft and modules on the USOS, hold crew members and equipment in place during EVAs and move Dextre around to perform tasks.[158] Dextre is a 1,560 kg (3,440 lb) robotic manipulator with two arms, a rotating torso and has power tools, lights and video for replacing orbital replacement units (ORUs) and performing other tasks requiring fine control.[159] The Mobile Base System (MBS) is a platform which rides on rails along the length of the station's main truss. It serves as a mobile base for Canadarm2 and Dextre, allowing the robotic arms to reach all parts of the USOS.[160] To gain access to the Russian Segment a grapple fixture was added to Zarya on STS-134, so that Canadarm2 can inchworm itself onto the ROS.[161] Also installed during STS-134 was the 15 m (50 ft) Orbiter Boom Sensor System (OBSS), which had been used to inspect heat shield tiles on Space Shuttle missions and can be used on station to increase the reach of the MSS.[161] Staff on Earth or the station can operate the MSS components via remote control, performing work outside the station without space walks.

 

Japan's Remote Manipulator System, which services the Kibō Exposed Facility,[162] was launched on STS-124 and is attached to the Kibō Pressurised Module.[163] The arm is similar to the Space Shuttle arm as it is permanently attached at one end and has a latching end effector for standard grapple fixtures at the other.

 

The European Robotic Arm, which will service the Russian Orbital Segment, will be launched alongside the Multipurpose Laboratory Module in 2017.[164] The ROS does not require spacecraft or modules to be manipulated, as all spacecraft and modules dock automatically and may be discarded the same way. Crew use the two Strela (Russian: Стрела́; lit. Arrow) cargo cranes during EVAs for moving crew and equipment around the ROS. Each Strela crane has a mass of 45 kg (99 lb).

Planned componments

Nauka

Artist's rendering of the Nauka module docked to Zvezda.

Main article: Nauka (ISS module)

 

Nauka (Russian: Нау́ка; lit. Science), also known as the Multipurpose Laboratory Module (MLM), (Russian: Многофункциональный лабораторный модуль, or МЛМ), is a component of the ISS which has not yet been launched into space. The MLM is funded by the Roscosmos State Corporation. In the original ISS plans, Nauka was to use the location of the Docking and Stowage Module. Later, the DSM was replaced by the Rassvet module and it was moved to Zarya's nadir port. Planners anticipate Nauka will dock at Zvezda's nadir port, replacing Pirs.[165]

 

The launch of Nauka, initially planned for 2007, has been repeatedly delayed for various reasons. As of September 2019, the launch to the ISS is assigned to no earlier than December 2020.[166] After this date, the warranties of some of Nauka's systems will expire.

Prichal

Mockup of the Prichal module at the Yuri Gagarin Cosmonaut Training Center

Main article: Prichal (ISS module)

 

Prichal, also known as Uzlovoy Module or UM (Russian: Узловой Модуль "Причал", Nodal Module Berth),[167] is a 4-tonne (8,800 lb)[168] ball-shaped module that will allow docking of two scientific and power modules during the final stage of the station assembly, and provide the Russian segment additional docking ports to receive Soyuz MS and Progress MS spacecraft. UM is due to be launched in 2022.[169] It will be integrated with a special version of the Progress cargo ship and launched by a standard Soyuz rocket, docking to the nadir port of the Nauka module. One port is equipped with an active hybrid docking port, which enables docking with the MLM module. The remaining five ports are passive hybrids, enabling docking of Soyuz and Progress vehicles, as well as heavier modules and future spacecraft with modified docking systems. The node module was intended to serve as the only permanent element of the cancelled OPSEK.[170][171]

Science Power Modules 1 and 2

 

Science Power Module 1 (SPM-1, also known as NEM-1) Science Power Module 2 (SPM-2, also known as NEM-2) are modules planned to arrive at the ISS in 2022.[169][172][173] It is going to dock to the Prichal module, which is planned to be attached to the Nauka module.[173] If Nauka is cancelled, then the Prichal, SPM-1, and SPM-2 would dock at the zenith port of Zvezda. SPM-1 and SPM-2 would also be required components for the OPSEK space station.[174]

Bishop Airlock Module

Main article: Bishop Airlock Module

 

The NanoRacks Bishop Airlock Module is a commercially-funded airlock module intended to be launched to the ISS on SpaceX CRS-21 in August 2020.[175][176] The module is being built by NanoRacks, Thales Alenia Space, and Boeing.[177] It will be used to deploy CubeSats, small satellites, and other external payloads for NASA, CASIS, and other commercial and governmental customers.[178]

Cancelled componments

The cancelled Habitation module under construction at Michoud in 1997

 

Several modules planned for the station were cancelled over the course of the ISS programme. Reasons include budgetary constraints, the modules becoming unnecessary, and station redesigns after the 2003 Columbia disaster. The US Centrifuge Accommodations Module would have hosted science experiments in varying levels of artificial gravity.[179] The US Habitation Module would have served as the station's living quarters. Instead, the sleep stations are now spread throughout the station.[180] The US Interim Control Module and ISS Propulsion Module would have replaced the functions of Zvezda in case of a launch failure.[181] Two Russian Research Modules were planned for scientific research.[182] They would have docked to a Russian Universal Docking Module.[183] The Russian Science Power Platform would have supplied power to the Russian Orbital Segment independent of the ITS solar arrays.

Systems

Life support

Main articles: ISS ECLSS and Chemical oxygen generator

 

The critical systems are the atmosphere control system, the water supply system, the food supply facilities, the sanitation and hygiene equipment, and fire detection and suppression equipment. The Russian Orbital Segment's life support systems are contained in the Zvezda service module. Some of these systems are supplemented by equipment in the USOS. The MLM Nauka laboratory has a complete set of life support systems.

Atmospheric control systems

A flowchart diagram showing the components of the ISS life support system.

The interactions between the components of the ISS Environmental Control and Life Support System (ECLSS)

 

The atmosphere on board the ISS is similar to the Earth's.[184] Normal air pressure on the ISS is 101.3 kPa (14.69 psi);[185] the same as at sea level on Earth. An Earth-like atmosphere offers benefits for crew comfort, and is much safer than a pure oxygen atmosphere, because of the increased risk of a fire such as that responsible for the deaths of the Apollo 1 crew.[186] Earth-like atmospheric conditions have been maintained on all Russian and Soviet spacecraft.[187]

 

The Elektron system aboard Zvezda and a similar system in Destiny generate oxygen aboard the station.[188] The crew has a backup option in the form of bottled oxygen and Solid Fuel Oxygen Generation (SFOG) canisters, a chemical oxygen generator system.[189] Carbon dioxide is removed from the air by the Vozdukh system in Zvezda. Other by-products of human metabolism, such as methane from the intestines and ammonia from sweat, are removed by activated charcoal filters.[189]

 

Part of the ROS atmosphere control system is the oxygen supply. Triple-redundancy is provided by the Elektron unit, solid fuel generators, and stored oxygen. The primary supply of oxygen is the Elektron unit which produces O

2 and H

2 by electrolysis of water and vents H2 overboard. The 1 kW (1.3 hp) system uses approximately one litre of water per crew member per day. This water is either brought from Earth or recycled from other systems. Mir was the first spacecraft to use recycled water for oxygen production. The secondary oxygen supply is provided by burning O

2-producing Vika cartridges (see also ISS ECLSS). Each 'candle' takes 5–20 minutes to decompose at 450–500 °C (842–932 °F), producing 600 litres (130 imp gal; 160 US gal) of O

2. This unit is manually operated.[190]

 

The US Orbital Segment has redundant supplies of oxygen, from a pressurised storage tank on the Quest airlock module delivered in 2001, supplemented ten years later by ESA-built Advanced Closed-Loop System (ACLS) in the Tranquility module (Node 3), which produces O

2 by electrolysis.[191] Hydrogen produced is combined with carbon dioxide from the cabin atmosphere and converted to water and methane.

Power and thermal control

Main articles: Electrical system of the International Space Station and External Active Thermal Control System

Russian solar arrays, backlit by sunset

One of the eight truss mounted pairs of USOS solar arrays

 

Double-sided solar arrays provide electrical power to the ISS. These bifacial cells collect direct sunlight on one side and light reflected off from the Earth on the other, and are more efficient and operate at a lower temperature than single-sided cells commonly used on Earth.[192]

 

The Russian segment of the station, like most spacecraft, uses 28 volt low voltage DC from four rotating solar arrays mounted on Zarya and Zvezda. The USOS uses 130–180 V DC from the USOS PV array, power is stabilised and distributed at 160 V DC and converted to the user-required 124 V DC. The higher distribution voltage allows smaller, lighter conductors, at the expense of crew safety. The two station segments share power with converters.

 

The USOS solar arrays are arranged as four wing pairs, for a total production of 75 to 90 kilowatts.[193] These arrays normally track the sun to maximise power generation. Each array is about 375 m2 (4,036 sq ft) in area and 58 m (190 ft) long. In the complete configuration, the solar arrays track the sun by rotating the alpha gimbal once per orbit; the beta gimbal follows slower changes in the angle of the sun to the orbital plane. The Night Glider mode aligns the solar arrays parallel to the ground at night to reduce the significant aerodynamic drag at the station's relatively low orbital altitude.[194]

 

The station originally used rechargeable nickel–hydrogen batteries (NiH

2) for continuous power during the 35 minutes of every 90-minute orbit that it is eclipsed by the Earth. The batteries are recharged on the day side of the orbit. They had a 6.5-year lifetime (over 37,000 charge/discharge cycles) and were regularly replaced over the anticipated 20-year life of the station.[195] Starting in 2016, the nickel–hydrogen batteries were replaced by lithium-ion batteries, which are expected to last until the end of the ISS program.[196]

 

The station's large solar panels generate a high potential voltage difference between the station and the ionosphere. This could cause arcing through insulating surfaces and sputtering of conductive surfaces as ions are accelerated by the spacecraft plasma sheath. To mitigate this, plasma contactor units (PCU)s create current paths between the station and the ambient plasma field.[197]

ISS External Active Thermal Control System (EATCS) diagram

 

The station's systems and experiments consume a large amount of electrical power, almost all of which is converted to heat. To keep the internal temperature within workable limits, a passive thermal control system (PTCS) is made of external surface materials, insulation such as MLI, and heat pipes. If the PTCS cannot keep up with the heat load, an External Active Thermal Control System (EATCS) maintains the temperature. The EATCS consists of an internal, non-toxic, water coolant loop used to cool and dehumidify the atmosphere, which transfers collected heat into an external liquid ammonia loop. From the heat exchangers, ammonia is pumped into external radiators that emit heat as infrared radiation, then back to the station.[198] The EATCS provides cooling for all the US pressurised modules, including Kibō and Columbus, as well as the main power distribution electronics of the S0, S1 and P1 trusses. It can reject up to 70 kW. This is much more than the 14 kW of the Early External Active Thermal Control System (EEATCS) via the Early Ammonia Servicer (EAS), which was launched on STS-105 and installed onto the P6 Truss.[199]

Communications and computers

Main articles: Tracking and Data Relay Satellite and Luch (satellite)

See also: ThinkPad § Use in space

Diagram showing communications links between the ISS and other elements.

The communications systems used by the ISS

* Luch satellite and the Space Shuttle are not currently[when?] in use

 

Radio communications provide telemetry and scientific data links between the station and Mission Control Centres. Radio links are also used during rendezvous and docking procedures and for audio and video communication between crew members, flight controllers and family members. As a result, the ISS is equipped with internal and external communication systems used for different purposes.[200]

 

The Russian Orbital Segment communicates directly with the ground via the Lira antenna mounted to Zvezda.[6][201] The Lira antenna also has the capability to use the Luch data relay satellite system.[6] This system fell into disrepair during the 1990s, and so was not used during the early years of the ISS,[6][202][203] although two new Luch satellites—Luch-5A and Luch-5B—were launched in 2011 and 2012 respectively to restore the operational capability of the system.[204] Another Russian communications system is the Voskhod-M, which enables internal telephone communications between Zvezda, Zarya, Pirs, Poisk, and the USOS and provides a VHF radio link to ground control centres via antennas on Zvezda's exterior.[205]

 

The US Orbital Segment (USOS) makes use of two separate radio links mounted in the Z1 truss structure: the S band (audio) and Ku band (audio, video and data) systems. These transmissions are routed via the United States Tracking and Data Relay Satellite System (TDRSS) in geostationary orbit, allowing for almost continuous real-time communications with NASA's Mission Control Center (MCC-H) in Houston.[22][6][200] Data channels for the Canadarm2, European Columbus laboratory and Japanese Kibō modules were originally also routed via the S band and Ku band systems, with the European Data Relay System and a similar Japanese system intended to eventually complement the TDRSS in this role.[22][206] Communications between modules are carried on an internal wireless network.[207]

An array of laptops in the US lab

Laptop computers surround the Canadarm2 console

 

UHF radio is used by astronauts and cosmonauts conducting EVAs and other spacecraft that dock to or undock from the station.[6] Automated spacecraft are fitted with their own communications equipment; the ATV uses a laser attached to the spacecraft and the Proximity Communications Equipment attached to Zvezda to accurately dock with the station.[208][209]

 

The ISS is equipped with about 100 IBM/Lenovo ThinkPad and HP ZBook 15 laptop computers. The laptops have run Windows 95, Windows 2000, Windows XP, Windows 7, Windows 10 and Linux operating systems.[210] Each computer is a commercial off-the-shelf purchase which is then modified for safety and operation including updates to connectors, cooling and power to accommodate the station's 28V DC power system and weightless environment. Heat generated by the laptops does not rise but stagnates around the laptop, so additional forced ventilation is required. Laptops aboard the ISS are connected to the station's wireless LAN via Wi-Fi, which connects to the ground via Ku band. This provides speeds of 10 Mbit/s download and 3 Mbit/s upload from the station, comparable to home DSL connection speeds.[211][212] Laptop hard drives occasionally fail and must be replaced.[213] Other computer hardware failures include instances in 2001, 2007 and 2017; some of these failures have required EVAs to replace computer modules in externally mounted devices.[214][215][216][217]

 

The operating system used for key station functions is the Debian Linux distribution.[218] The migration from Microsoft Windows was made in May 2013 for reasons of reliability, stability and flexibility.[219]

 

In 2017, an SG100 Cloud Computer was launched to the ISS as part of OA-7 mission.[220] It was manufactured by NCSIST and designed in collaboration with Academia Sinica, and National Central University under contract for NASA.[221]

Operations

Expeditions and private flights

 

See also the list of International Space Station expeditions (professional crew), space tourism (private travellers), and the list of human spaceflights to the ISS (both).

 

Zarya and Unity were entered for the first time on 10 December 1998.

Soyuz TM-31 being prepared to bring the first resident crew to the station in October 2000

ISS was slowly assembled over a decade of spaceflights and crews

 

Each permanent crew is given an expedition number. Expeditions run up to six months, from launch until undocking, an 'increment' covers the same time period, but includes cargo ships and all activities. Expeditions 1 to 6 consisted of 3 person crews, Expeditions 7 to 12 were reduced to the safe minimum of two following the destruction of the NASA Shuttle Columbia. From Expedition 13 the crew gradually increased to 6 around 2010.[222][223] With the arrival of the US Commercial Crew vehicles in the late 2010s, expedition size may be increased to seven crew members, the number ISS is designed for.[224][225]

 

Gennady Padalka, member of Expeditions 9, 19/20, 31/32, and 43/44, and Commander of Expedition 11, has spent more time in space than anyone else, a total of 878 days, 11 hours, and 29 minutes.[226] Peggy Whitson has spent the most time in space of any American, totalling 665 days, 22 hours, and 22 minutes during her time on Expeditions 5, 16, and 50/51/52.[227]

 

Travellers who pay for their own passage into space are termed spaceflight participants by Roscosmos and NASA, and are sometimes referred to as space tourists, a term they generally dislike.[note 1] All seven were transported to the ISS on Russian Soyuz spacecraft. When professional crews change over in numbers not divisible by the three seats in a Soyuz, and a short-stay crewmember is not sent, the spare seat is sold by MirCorp through Space Adventures. When the space shuttle retired in 2011, and the station's crew size was reduced to 6, space tourism was halted, as the partners relied on Russian transport seats for access to the station. Soyuz flight schedules increase after 2013, allowing 5 Soyuz flights (15 seats) with only two expeditions (12 seats) required.[233] The remaining seats are sold for around US$40 million to members of the public who can pass a medical exam. ESA and NASA criticised private spaceflight at the beginning of the ISS, and NASA initially resisted training Dennis Tito, the first person to pay for his own passage to the ISS.[note 2]

 

Anousheh Ansari became the first Iranian in space and the first self-funded woman to fly to the station. Officials reported that her education and experience make her much more than a tourist, and her performance in training had been "excellent."[234] Ansari herself dismisses the idea that she is a tourist. She did Russian and European studies involving medicine and microbiology during her 10-day stay. The documentary Space Tourists follows her journey to the station, where she fulfilled "an age-old dream of man: to leave our planet as a "normal person" and travel into outer space."[235]

 

In 2008, spaceflight participant Richard Garriott placed a geocache aboard the ISS during his flight.[236] This is currently the only non-terrestrial geocache in existence.[237] At the same time, the Immortality Drive, an electronic record of eight digitised human DNA sequences, was placed aboard the ISS.[238]

Orbit

Graph showing the changing altitude of the ISS from November 1998 until November 2018

Animation of ISS orbit from 14 September 2018 to 14 November 2018. Earth is not shown.

 

The ISS is maintained in a nearly circular orbit with a minimum mean altitude of 330 km (205 mi) and a maximum of 410 km (255 mi), in the centre of the thermosphere, at an inclination of 51.6 degrees to Earth's equator. This orbit was selected because it is the lowest inclination that can be directly reached by Russian Soyuz and Progress spacecraft launched from Baikonur Cosmodrome at 46° N latitude without overflying China or dropping spent rocket stages in inhabited areas.[239][240] It travels at an average speed of 27,724 kilometres per hour (17,227 mph), and completes 15.54 orbits per day (93 minutes per orbit).[2][14] The station's altitude was allowed to fall around the time of each NASA shuttle flight to permit heavier loads to be transferred to the station. After the retirement of the shuttle, the nominal orbit of the space station was raised in altitude.[241][242] Other, more frequent supply ships do not require this adjustment as they are substantially higher performance vehicles.[28][243]

 

Orbital boosting can be performed by the station's two main engines on the Zvezda service module, or Russian or European spacecraft docked to Zvezda's aft port. The ATV is constructed with the possibility of adding a second docking port to its aft end, allowing other craft to dock and boost the station. It takes approximately two orbits (three hours) for the boost to a higher altitude to be completed.[243] Maintaining ISS altitude uses about 7.5 tonnes of chemical fuel per annum[244] at an annual cost of about $210 million.[245]

Orbits of the ISS, shown in April 2013

 

The Russian Orbital Segment contains the Data Management System, which handles Guidance, Navigation and Control (ROS GNC) for the entire station.[246] Initially, Zarya, the first module of the station, controlled the station until a short time after the Russian service module Zvezda docked and was transferred control. Zvezda contains the ESA built DMS-R Data Management System.[247] Using two fault-tolerant computers (FTC), Zvezda computes the station's position and orbital trajectory using redundant Earth horizon sensors, Solar

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