Contents1 Purpose o 1.1 Scientific research o 1.2 Exploration o 1.3 Education and cultural outreach2 Origins o 2.1 Mir-2 o 2.2 Freedom with Kibō o 2.3 Columbus3 Station structure o 3.1 Assembly o 3.2 Pressurised modules o 3.3 Unpressurized elements4 Station systems o 4.1 Life support o 4.2 Power and thermal control o 4.3 Communications and computers5 Station operations o 5.1 Expeditions and private flights o 5.2 Crew activities o 5.3 Orbit and mission control o 5.4 Repairs6 Fleet operations o 6.1 Currently docked/berthed o 6.2 Scheduled launches and dockings/berthings o 6.3 Docking o 6.4 Launch and docking windows7 Sightings o 7.1 Naked eye o 7.2 Astrophotography8 Crew health and safety o 8.1 Radiation o 8.2 Stress
o 8.3 Medical o 8.4 Orbital debris9 Politics o 9.1 International co-operation o 9.2 China o 9.3 End of mission o 9.4 Program cost in United States dollars10 Notes11 References12 External links o 12.1 Childrens websites o 12.2 Live viewing o 12.3 Contact the crew o 12.4 Video o 12.5 Image galleries o 12.6 Research o 12.7 Travel agency website
International Space StationThe International Space Station, as seen from Space ShuttleEndeavour inMay 2011.ISS insigniaStation statisticsCOSPAR ID 1998-067ACall sign Alpha Fully crewed 6Crew Currently onboard 6 (Expedition 34)Launch 1998–2020 Baikonur LC-81/23, LC-1/5Launch pad KSC LC-39,Mass approximately 450,000 kg (990,000 lb)Length 72.8 mWidth 108.5 m c. 20 m (c. 66 ft)Height nadir–zenith, arrays forward–aft (27 November 2009)[dated info] 837 m3 (29,600 cu ft)Pressurised volume (21 March 2011)Atmospheric pressure 101.3 kPa (29.91 inHg, 1 atm)
402 km (250 mi) AMSLPerigee (02 November 2012 04:38:51 epoch) 424 km (263 mi) AMSLApogee (02 November 2012 04:38:51 epoch)Orbital inclination 51.6 degrees 7,706.6 m/sAverage speed (27,743.8 km/h, 17,239.2 mph) 92 minutes 50 secondsOrbital period (02 November 2012 04:38:51 epoch) 5140Days in orbit (16 December) 4427Days occupied (16 December) 80680Number of orbits (16 December)Orbital decay 2 km/monthStatistics as of 9 March 2011(unless noted otherwise)References: ConfigurationStation elements as of December 2011, but missing Pirs(exploded view)The International Space Station (ISS) is a habitable artificial satellite in low Earth orbit. It followsthe Salyut, Almaz, Skylab and Mir stations as the ninth space station to be inhabited. The ISS is amodular structure whose first component was launched in 1998. Like many artificial satellites, the station
can be seen with the naked eye from Earth without any special equipment. The ISS consists ofpressurised modules, external trusses, solar arrays and other components. ISS components have been launched by American Space Shuttles as well as Russian Proton and Soyuz rockets. Budgetconstraints led to the merger of three space station projects with the Japanese Kibō moduleand Canadian robotics. In 1993 the partially built Soviet/Russian Mir-2, the proposed American Freedom, and the proposed European Columbus merged into a single multinational programme. The RussianFederal Space Agency (RSA/RKA) is using the ISS as a work site to assemble their next space station,called OPSEK. Modules and components for the new station began arriving on orbit in 2010, and theRSA plans to commission the new station before the remainder of the ISS is de-orbited.The ISS serves as a microgravity and space environment research laboratory in which crew membersconduct experiments in biology, human biology, physics, astronomy, meteorology and other fields. The station is suited for the testing of spacecraft systems and equipment required for missions to the Moon and Mars.The station has been continuously occupied for 12 years and 44 days, having exceeded the previousrecord of almost 10 years (or 3,634 days) held by Mir, in 2010. The station is serviced by Soyuz spacecraft, Progress spacecraft, the Automated Transfer Vehicle, the H-II Transfer Vehicle, andformerly the Space Shuttle. It has been visited by astronauts and cosmonauts from 15 different nations. On 25 May 2012, Space Exploration Technologies Corporation (or SpaceX) became theworlds first privately held company to send a cargo load, via the Dragon spacecraft, to the International Space Station.The ISS programme is a joint project between five participating space agencies: NASA, the Russian Federal Space Agency, JAXA, ESA, and CSA. The ownership and use of the space station is established by intergovernmental treaties and agreements. The station is divided into two sections,the Russian orbital segment (ROS) and the United States orbital segment (USOS), which is shared bymany nations. The ISS is maintained at an orbital altitude of between 330 km (205 mi) and 410 km (255 mi). It completes 15.7 orbits per day. The ISS is funded until 2020, and may operate until 2028.
PurposeAccording to the original Memorandum of Understanding between NASA and RSA, the InternationalSpace Station was intended to be a laboratory, observatory and factory in space. It was also planned toprovide transportation, maintenance, and act as a staging base for possible future missions to the Moon, Mars and asteroids. In the 2010 United States National Space Policy, the ISS was given additional  roles of serving commercial, diplomatic and educational purposes.Scientific researchMain article: Scientific research on the ISSThe ISS provides a platform to conduct scientific research that cannot be performed in any other way.While small unmanned spacecraft can provide platforms for zero gravity and exposure to space, spacestations offer a long term environment where studies can be performed potentially for decades, combinedwith ready access by human researchers over periods that exceed the capabilities of manned spacecraft.The Station simplifies individual experiments by eliminating the need for separate rocket launches andresearch staff. The primary fields of research include Astrobiology, astronomy, humanresearch including space medicine and life sciences, physical sciences, materials science, Space weather and weather on Earth (meteorology). Scientists on Earth have access to the crewsdata and can modify experiments or launch new ones, benefits generally unavailable on unmanned spacecraft. Crews fly expeditions of several months duration, providing approximately 160 man-hours a week of labour with a crew of 6.Kibō is intended to accelerate Japans progress in science and technology, gain new knowledge and apply it to such fields as industry and medicine.In order to detect dark matter and answer other fundamental questions about our universe, engineers andscientists from all over the world built the Alpha Magnetic Spectrometer (AMS), which NASA compares tothe Hubble telescope, and says could not be accommodated on a free flying satellite platform due in part to its power requirements and data bandwidth needs.
The space environment is hostile to life. Unprotected presence in space is characterised by an intenseradiation 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. Some simple forms  of life called extremophiles, including small invertebrates called tardigrades can survive in thisenvironment in an extremely dry state called 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 whetherlengthy human spaceflight and space colonisation are feasible. As of 2006, data on bone loss andmuscular atrophy suggest that there would be a significant risk of fractures and movement problems ifastronauts landed on a planet after a lengthy interplanetary cruise, such as the six-month interval required to travel to Mars. Medical studies are conducted aboard the ISS on behalf of the NationalSpace Biomedical Research Institute (NSBRI). Prominent among these is the Advanced DiagnosticUltrasound in Microgravity study in which astronauts perform ultrasound scans under the guidance ofremote 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 anticipatedthat remotely guided ultrasound scans will have application on Earth in emergency and rural care situations where access to a trained physician is difficult.MicrogravityA comparison between the combustion of a candle on Earth (left) and in a microgravity environment, such as that found onthe ISS (right)Contrary to popular belief, the earths gravity is only slightly less at the altitude of the ISS as at thesurface. According to the equivalence principle, gravity only seems absent because, like any orbitingobject, it is in continuous freefall. This state of perceived weightlessness is not perfect however, being disturbed by five separate effects: Drag from the residual atmosphere; when the ISS enters the Earths shadow, the main solar panels are rotated to minimise this aerodynamic drag, helping reduce orbital decay.
Vibration from movements of mechanical systems and the crew. Actuation of the on-board altitude control moment gyroscopes. Thruster firings for altitude or orbital changes. Gravity-gradient effects, also known as tidal effects. Items not at the exact ISS center of mass would, if not attached to the station, follow slightly different orbits than that of the ISS as a whole. Those closer to the earth would tend to follow faster, shorter orbits and move forward along the velocity vector. Those farther away would have slower, longer orbits and move rearward against the velocity vector. Those to the left or right of the ISS center of mass would be in different orbital planes. Being attached to the rigid ISS, however, these items experience small forces that keep them moving along with the ISS center of mass.Researchers are investigating the effect of the stations 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 microgravitys effects on the growth of three-dimensional, human-like tissues, and the unusual protein crystals that can be formed in space.The investigation of the physics of fluids in microgravity will allow researchers to model the behaviour offluids better. Because fluids can be almost completely combined in microgravity, physicists investigatefluids that do not mix well on Earth. In addition, an examination of reactions that are slowed by low gravity and temperatures will give scientists a deeper understanding ofsuperconductivity.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. Other areas of interestinclude the effect of the low gravity environment on combustion, through the study of the efficiency ofburning and control of emissions and pollutants. These findings may improve current knowledge aboutenergy production, and lead to economic and environmental benefits. Future plans are for theresearchers aboard the ISS to examine aerosols, ozone, water vapour, and oxidesin Earths atmosphere, as well as cosmic rays, cosmic dust, antimatter, and dark matter in the universe.ExplorationA 3D plan of the MARS-500 complex, used for ground-based experiments which complement ISS-based preparations foramanned mission to MarsThe ISS provides a location in the relative safety of Low Earth Orbit to test spacecraft systems that will berequired 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. Referring to theMARS-500 experiment, ESA states that "Whereasthe ISS is essential for answering questions concerning the possible impact of weightlessness, radiationand other space-specific factors, aspects such as the effect of long-term isolation and confinement can be more appropriately addressed via ground-based simulations". Sergey Krasnov, the head of humanspace flight programmes for Russias space agency, Roscosmos, in 2011 suggested a "shorter version" of MARS-500 may be carried out on the ISS.In 2009, noting the value of the partnership framework itself, Sergey Krasnov wrote, "When comparedwith partners acting separately, partners developing complementary abilities and resources could give usmuch more assurance of the success and safety of space exploration. The ISS is helping further advancenear-Earth space exploration and realisation of prospective programmes of research and exploration of the Solar system, including the Moon and Mars." A manned mission to Mars, however, may be amultinational effort involving space agencies and countries outside of the current ISS partnership. In 2010ESA Director-General Jean-Jacques Dordain stated his agency was ready to propose to the other 4 partners that China, India and South Korea be invited to join the ISS partnership. NASA chief Charlie Bolden stated in Feb 2011 "Any mission to Mars is likely to be a global effort". Currently, American legislation prevents NASA co-operation with China on space projects.Education and cultural outreachThe ISS crew provide 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. ESA offers a wide range of free teaching materials that can be downloaded for use in classrooms. In one lesson, studentscan navigate a 3-D model of the interior and exterior of the ISS, and face spontaneous challenges to solve in real time.JAXA aims both to "Stimulate the curiosity of children, cultivating their spirits, and encouraging theirpassion to pursue craftsmanship", and to "Heighten the childs awareness of the importance of life and their responsibilities in society." Through a series of education guides, a deeper understanding of the past and near-term future of manned space flight, as well as that of Earth and life, will be learned. Inthe JAXA Seeds in Space experiments, the mutation effects of spaceflight on plant seeds aboard the ISSis explored. Students grow sunflower seeds which flew on the ISS for about nine months as a start to‗touch the Universe‘. 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. Susan J. Helms, Expedition Two flight engineer, A student speaks to crew
talks to amateur radio operators on Earth from using Amateur Radio, the Amateur radio workstation in the Zarya. provided free by ARISS.Cultural activities are another major objective. Tetsuo Tanaka, director of JAXAs Space Environment andUtilization Center, says "There is something about space that touches even people who are not interested in science."Amateur Radio on the ISS (ARISS) is a volunteer programme which encourages students worldwide topursue careers in science, technology, engineering and mathematics through amateurradio communications opportunities with the ISS crew. ARISS is an international working group,consisting of delegations from 9 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.First Orbit is a feature-length documentary film about Vostok 1, the first manned space flight around theEarth. 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 ESAastronaut Paolo Nespoli were able to film the view that Yuri Gagarin saw on his pioneering orbital spaceflight. This new footage was cut together with the original Vostok 1 mission audio recordings sourced fromthe 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. The film was streamed through the website www.firstorbit.org in a global YouTube premiere in 2011, under a free license.OriginsThe International Space Station programme represents a combination of three national space stationprojects: the Russian/Soviet Mir-2, NASAs Freedom including the Japanese Kibō laboratory, and theEuropean Columbus space stations. Canadian robotics supplement these projects.Mir-2 was originally authorised in the February 1976 resolution setting forth plans for development of thirdgeneration Soviet space systems; the first module, which would have served the same function as Zarya,was destroyed in a launch mishap.In the early 1980s, NASA planned to launch a modular space station called Freedom as a counterpart tothe Soviet Salyut and Mir space stations. Freedom was never constructed and the remnants of the projectbecame part of the ISS. The Japanese Experiment Module (JEM), or Kibō, was announced in 1985, aspart of the Freedom space station in response to a NASA request in 1982.In Rome in early 1985, science ministers from the European Space Agency (ESA) countries approvedthe Columbus program, the most ambitious effort in space undertaken by that organisation at the time.The plan spearheaded by Germany and Italy included a module which would be attached to Freedom,and with the capability to evolve into a full-fledged European orbital outpost before the end of the century.The space station was also going to tie the emerging European and Japanese national spaceprogrammes closer to the U.S.-led project, thereby preventing those nations from becoming major, independent competitors too.In September 1993, American Vice-President Al Gore and Russian Prime Minister ViktorChernomyrdin announced plans for a new space station, which eventually became the International
Space Station. They also agreed, in preparation for this new project, that the United States would be involved in the Mir programme, including American Shuttles docking, in the Shuttle-Mir Program.Mir-2Main articles: Mir, Mir-2, Polyus (spacecraft), Buran program, and EnergiaThe Soviet Buran shuttle would have carried modules up to 30 tons to MIR-2. 80–100 ton modules could have used itslauncher without the shuttle (seen here withAn-225, the heaviest aeroplane).The Russian Orbital Segment (ROS or RS) is the eleventh Soviet-Russian space station. Mir ("Peace")and the ISS are successors to the Salyut("Fireworks") and Almaz ("Diamond") stations. The first MIR-2module was launched in 1986 by an Energia heavy-lift expendable launch system. The launcher workedproperly, however the Polyus payload fired its engines to insert itself into orbit whilst in the wrong positiondue to a programming error, and re-entered the atmosphere. The planned station changed several times,but Zvezda was always the service module, containing the stations critical systems such as life support.The station would have used the Buran spaceplane and Proton rockets to lift new modules into orbit. Thespaceframe of Zvezda, also called DOS-8 serial number 128, was completed in February 1985 and major internal equipment was installed by October 1986.The Polyus module or spacecraft would have served as the FGB, a foundation which provides propulsionand guidance, but it lacks life support. Polyus was a satellite interceptor/destroyer, carrying a 1 megawattcarbon dioxide laser. The module had a length of almost 37 m and a diameter of 4.1 m, weighed nearly80 t, and included 2 principal sections, the smallest, the functional service block (FGB), and the largest, the aim module.In 1983, the design was changed and the station would consist of Zvezda, followed by several 90 metricton modules and a truss structure similar to the current station. The draft was approved by NPO EnergiaChief Semenov on 14 December 1987 and announced to the press as Mir-2 in January 1988. Thisstation would be visited by the Soviet Buran, but mainly resupplied by Progress-M2 spacecraft. Orbital assembly of the station was expected to begin in 1993. In 1993 with the collapse of the Soviet Union, aredesigned smaller Mir-2 was to be built whilst attached to Mir, just as OPSEK is being assembled whilstattached to the ISS.Freedom with KibōMain articles: Space Station Freedom, Kibō, and H-II Transfer Vehicle
Artists conception of the proposed "Power Tower" space station with the Japanese Experiment Module attachedApproved by then-president Ronald Reagan and announced in the 1984 State of the Union Address, "Wecan follow our dreams to distant stars, living and working in space for peaceful economic and scientificgain", the proposed Freedom changed considerably.NASAs first cost assessment in 1987 revealed the "Dual Keel" Station would cost $14.5 billion. Thiscaused a political uproar in Congress, and NASA and Reagan Administration officials reached acompromise in March 1987 which allowed the agency to proceed with a cheaper $12.2-billion Phase OneStation that could be completed after 10 or 11 Shuttle assembly flights. This design initially omitted the$3.4-billion Dual Keel structure and half of the power generators. The new Space Station configurationwas named Freedom by Reagan in June 1988. Originally, Freedom would have carried two 37.5 kW solararrays. However, Congress quickly insisted on adding two more arrays for scientific users. The SpaceStation programme was plagued by conflicts during the entire 1984–87 definition phase. In 1987, theDepartment of Defense (DoD) briefly demanded to have full access to the Station for military research,despite strong objections from NASA and the international partners. Besides the expected furore from theinternational partners, the DoD position sparked a shouting match between Defense Secretary CasparWeinberger and powerful members of Congress that extended right up to the final Fiscal 1988 budget authorisation in July 1987. Reagan wanted to invite other NATO countries to participate in the U.S-ledproject, since the Soviet Union had been launching international crews to their Salyut space stationssince 1971. At one point, then-anonymous disgruntled NASA employees calling themselves "Center forStrategic Space Studies" suggested that instead of building Freedom, NASA should take the back-up Skylab from display in the National Air and Space Museum in Washington and launch that.An agreement signed in September 1988 allocated 97% of the US lab resources to NASA while theCanadian CSA would receive 3% in return for its contribution to the programme. Europe and Japan wouldretain 51% of their own laboratory modules. Six Americans and two international astronauts would bepermanently based on Space Station Freedom. Several NASA Space Shuttle missions in the 1980s andearly 1990s included spacewalks to demonstrate and test space station construction techniques.
The Japanese Experiment Module (JEM), christened Kibō ("hope") in 1999, is Japans first mannedspacecraft. Kibō consists of a pressurised laboratory dedicated to advanced technology experiments,education and art, a cargo bay, an unpressurised pallet for vacuum experiments in space, a robotic arm,and interorbital communication system. While the proposed space station was redesigned many timesaround Kibō, the only significant change has been the placement of its ballistic shielding. Its final positionat the front of the station increases the risk of damage from debris. The ESA and NASA, by contrast, bothreduced the size of their laboratories over the course of the program. The Japanese National SpaceDevelopment Agency (NASDA) formally submitted the JEM proposal to NASA in March 1986, and by 1990 design work began. Constructed in the Tobishima Plant of Nagoya Aerospace SystemsWorks, by Mitsubishi Heavy Industries, Ltd., Kibō made its way to the Tsukuba Space Center and in 2003Kibō was shipped, first by river barge and then by ship, to America. In 2010, Kibō won the Good DesignAward, a 55 year old consumer and industry award which identifies the best of Japanese craftsmanship.A decade before Zarya was launched into orbit, Japan was working on the development of its own spaceshuttle, intended to use the H-II launcher. Depending on the configuration of the launcher, it would weighbetween 10 and 20 metric tons and mix crew and cargo together. It would take off vertically on its boosterand at the end of its mission re-enter and land just as the NASA and Soviet shuttles did. The program was terminated by JAXA in 2003 after scale mockup testing.
ColumbusMain articles: Columbus ISS module, Man-Tended Free Flyer, and Hermes spaceplaneThe first elements of the Columbus program were expected to fly as early as 1992, to coincide with the500th anniversary of Columbus voyage to America. ESA and NASA clashed over the very concept of theColumbus program in 1986. America objected to ESAs using Columbus as building block of a futureEuropean space station, and were concerned that they would facilitate the creation of a potentialcompetitor if the manned space outpost fulfilled its promise as supplier of commercially viable products,such as new materials and pharmaceuticals. Plans were scaled down as a result, and by 1988, Europeproposed to participate with three elements, the Columbus module, the Man-Tended Free Flyer (MTFF),  and the Polar Platform (PPF), supported by theAriane-5 launcher and the Hermes spaceplane.The Columbus Man-Tended Free Flyer (MTFF) was an ESA programme to develop a space station thatcould be used for a variety of microgravity experiments while serving ESAs needs for an autonomous manned space platform. The MTFF would be a space station without long term life support, visited byshort term crews to replenish and maintain experiments in a Zero-G environment free of vibrationscaused by a permanent crew. The project was canceled after budget constraints caused by Germanreunification. The Hermes spaceplane is comparable in function to the American and Soviet spaceshuttles, with a smaller crew of up to 6 (reduced to 3 with ejection seats after the Columbia disaster) andsubstantially smaller cargo capacity, 4,550 kg, comparable to ISS unmanned cargo ships.By 1991 the Columbus and Hermes pre-development activities were good enough to progress into fulldevelopment, however profound geopolitical changes prompted examining broader internationalcooperation, in particular with the Russian Federation. ESA Member States approved the completedevelopment of the Attached Pressurised Module (APM) and the Polar Platform (PPF) for Columbus, butthe Man-Tended Free-Flyer (MTFF) was abandoned. The Hermes programme was reoriented into theManned Space Transportation Programme (MSTP), and a three-year period extending from 1993 to 1995was agreed on in order to define a future manned space transportation system in cooperation with Russia, including joint development and use of Mir-2.The ESA ATV robot spacecraft is a powerful space tug that can be adapted to shuttle supplies into Mars orbit. Its propulsion is arranged with a central hollow section, to allow the possibility of a docking port atboth ends. It could then form larger assemblies, strung together as a space station or allowing piggyback docking to Zvezda.Station structure
Expedition 18 commander Michael Finckes Station layout, photographed from Soyuz TMA-20, video tour of the habitable part of the ISS with NASAs Endeavour docked from January 2009The ISS follows Salyut and Almaz series, Cosmos 557, Skylab, and Mir as the 11th space stationlaunched, as the Genesis prototypes were never intended to be manned. The ISS is a third  generation modular space station.Other examples of modular station projects include the Soviet/Russian Mir, Russian OPSEK,and Chinese space station. The first space station, Salyut 1, and other one-piece or monolithic firstgeneration space stations, such as Salyut 2,3,4,5, DOS 2, Kosmos 557, Almaz and NASAs Skylab stations were not designed for re-supply. Generally, each crew had to depart the stationto free the only docking port for the next crew to arrive, Skylab had more than one docking port but wasnot designed for resupply. Salyut 6 and 7 had more than one docking port and were designed to be resupplied routinely during crewed operation. Modular stations can allow the mission to be changedover time and new modules can be added or removed from the existing structure, allowing greaterflexibility.Below is a diagram of major station components. The blue areas are pressurised sections accessible bythe crew without using spacesuits. The stations unpressurised superstructure is indicated in red. Otherunpressurised components are yellow. Note that the Unity node joins directly to the Destiny laboratory.For clarity, they are shown apart. Russian docking port Solar Zvezda DOS-8 Solar array Service Module array Russian Poisk(MRM-2) Pirs Russian docking port Airlock Airlock docking port
Nauka lab to European Replace Pirs Robotic Arm Solar Zarya FGB Solar array (first module) array Leonardo Rassvet Russian cargo bay (MRM-1) docking port PMA 1 Quest Unity Tranquility PMA 3 Airlock Node 1 Node 3 docking port ESP-2 CupolaSolar Heat Heat Solar array Solar array Solar arrayarray Radiator Radiator ELC 2, AMS Z1 truss ELC 3 S5/6 Truss S3/S4 Truss S1 Truss S0 Truss P1 Truss P3/P4 Truss P5/6 Truss ELC 4, ESP ELC 1 3 Dextre Canadarm2Solar Solar array Solar array Solar arrayarray External Destiny stowage Laboratory Kibō logistics Cargo Bay HTV/Dragon berth HTV/Dragon berth (docking port) (docking port)
Robotic Arm External Columbus Harmony Kibō Kibō Payloads Laboratory (Node 2) Laboratory External Platform PMA 2 docking portAssemblyMain article: Assembly of the International Space StationSee also: List of ISS spacewalksRon Garan during STS-124 uses a computer controlled screwdriver for speed, torque and number of turns.The assembly of the International Space Station, a major endeavour in space architecture, began in November 1998. Russian modules launched and docked robotically, with the exception of Rassvet. Allother modules were delivered by the Space Shuttle, which required installation by ISS and shuttlecrewmembers using the SSRMS and EVAs; as of 5 June 2011, they had added 159 components duringmore than 1,000 hours of EVA activity. 127 of these spacewalks originated from the station, while the remaining 32 were launched from the airlocks of docked Space Shuttles. The beta angle of the stationhad to be considered at all times during construction, as the stations beta angle is directly related to thepercentage of its orbit that the station (as well as any docked or docking spacecraft) is exposed to the sun; the Space Shuttle would not perform optimally above a limit called the "beta cutoff". Rassvet wasdelivered by NASAs Atlantis Space Shuttle in 2010 in exchange for the Russian Proton delivery of the United States-funded Russian-built Zarya Module in 1998. Robot arms rather than EVAs were utilisedin its installation (docking).The first segment of the ISS, Zarya, was launched on 20 November 1998 on an autonomousRussian Proton rocket. It provided propulsion, orientation control, communications, electrical power, butlacked long-term life support functions. Two weeks later a passive NASA module Unity was launchedaboard Space Shuttle flight STS-88 and attached to Zarya by astronauts during EVAs. This module hastwo Pressurized Mating Adapters (PMAs), one connects permanently to Zarya, the other allows theSpace Shuttle to dock to the space station. At this time, the Russian station Mir was still inhabited. The
ISS remained unmanned for two years, during which time Mir was de-orbited. On 12 July2000 Zvezda was launched into orbit. Preprogrammed commands on board deployed its solar arrays andcommunications antenna. It then became the passive vehicle for a rendezvous with the Zarya and Unity.As a passive "target" vehicle, the Zvezda maintained a stationkeeping orbit as the Zarya-Unity vehicleperformed the rendezvous and docking via ground control and the Russian automated rendezvous anddocking system. Zaryas computer transferred control of the station to Zvezdas computer soon afterdocking. Zvezda added sleeping quarters, a toilet, kitchen, CO2 scrubbers, dehumidifier, oxygengenerators, exercise equipment, plus data, voice and television communications with mission control. This enabled permanent habitation of the station.The first resident crew, Expedition 1, arrived in November 2000 on Soyuz TM-31, midway between theflights of STS-92 and STS-97. These two Space Shuttle flights each added segments of thestations Integrated Truss Structure, which provided the station with Ku-band communication for U.S.television, additional attitude support needed for the additional weight of the USOS, and substantial solar arrays supplementing the stations existing 4 solar arrays.Partially constructed ISS in December 2002Over the next two years the station continued to expand. A Soyuz-U rocket delivered the Pirs dockingcompartment. The Space Shuttles Discovery,Atlantis, and Endeavour deliveredthe Destiny laboratory and Quest airlock, in addition to the stations main robot arm, the Canadarm2, andseveral more segments of the Integrated Truss Structure.The expansion schedule was interrupted by the destruction of the Space Shuttle Columbia on STS-107 in2003, with the resulting hiatus in the Space Shuttle programme halting station assembly until the launch of Discovery on STS-114 in 2005.The official resumption of assembly was marked by the arrival of Atlantis, flying STS-115, which deliveredthe stations second set of solar arrays. Several more truss segments and a third set of arrays weredelivered on STS-116, STS-117, and STS-118. As a result of the major expansion of the stations power-generating capabilities, more pressurised modules could be accommodated, and the Harmony nodeand Columbus European laboratory were added. These were followed shortly after by the first twocomponents of Kibō. In March 2009, STS-119 completed the Integrated Truss Structure with theinstallation of the fourth and final set of solar arrays. The final section of Kibō was delivered in July 2009on STS-127, followed by the Russian Poisk module. The third node, Tranquility, was delivered inFebruary 2010 during STS-130 by the Space Shuttle Endeavour, alongside the Cupola, closely followedin May 2010 by the penultimate Russian module, Rassvet, delivered by Space Shuttle Atlantis on STS-132. The last pressurised module of the USOS, Leonardo, was brought to the station by Discovery on her
final flight, STS-133, followed by the Alpha Magnetic Spectrometer on STS-134, delivered by Endeavour.ISS in orbit docked with the Space Shuttle Endeavour in May 2011As of June 2011, the station consisted of fifteen pressurised modules and the Integrated Truss Structure.Still to be launched are the RussianMultipurpose Laboratory Module Nauka and a number of externalcomponents, including the European Robotic Arm. Assembly is expected to be completed by 2012, by which point the station will have a mass in excess of 400 metric tons (440 short tons).The gross mass of the station is not possible to calculate with precision. The total launch weight of the modules on orbit is 417,289 kg (919,960 lb) (as of 03/09/2011). 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. Gas (Hydrogen) is constantly vented overboard bythe Oxygen generators.Pressurised modulesMain article: Assembly sequence Unity node (top) and Zarya From top to bottom: Unity, Zarya, (with solar panels deployed) Zvezda modules with Progress M1- in 1998 3 dockedZarya (Russian: ; lit. dawn), also known as the Functional Cargo Block or FGB(Russian: ФГБ),was the first module of the station, launched on 20 November 1998 on a Russian Proton rocket from Site
81 in the first and largest spaceport, Baikonur to a 400 km (250 mi) high orbit. After parking in orbit, theZarya Module provided orientation control, communications and electrical power for itself, and for thepassive Node 1 (Unity) attached later, while the station awaited launch of the third component, a Russian-provided crew living quarters and early station core, the service module Zvezda. The Service Moduleenhanced or replaced many functions of Zarya. The FGB is a descendant of the TKS spacecraft designedfor the Russian Salyut programme. 6,100 kg of propellant fuel can be stored and transferred automaticallyto and from ships docked to the Russian portion of the station – the Russian Orbital Segment (ROS).Zarya was originally intended as a module for the Russian Mir space station, but was not flown as of theend of the Mir-1 programme. Development costs for Zarya were paid for by Russia (and the former SovietUnion), spread across previous space station programmes, and some construction and preparation costswere paid for by the United States.Unity, a passive connecting module was the first U.S.-built component of the Station. It is cylindrical inshape, with six berthing locations facilitating connections to other modules. Unity was carried into orbit asthe primary cargo of STS-88 in 1998.Zvezda (Russian: Звезда, meaning "star"), DOS-8, also known as the ServiceModule or SM (Russian: СМ). It provides all of the stations critical systems, its addition rendered thestation permanently habitable for the first time, adding life support for up to six crew and living quarters for two. Zvezdas DMS-R computer handles guidance, navigation & control for the entire space station. Asecond computer which performs the same functions is installed in the Nauka FGB-2. The rocket used for Zvezdas launch was one of the first to carry advertising. The space frame was completed in February1985, major internal equipment was installed by October 1986, and it was launched on 12 July 2000.Zvezda is at the rear of the station according to its normal direction of travel and orientation, its enginesare used to boost the stations orbit. Alternatively Russian and European spacecraft can dock to Zvezdasaft (rear) port and use their engines to boost the station.Destiny is the primary research facility for United States payloads aboard the ISS. In 2011, NASAsolicited proposals for a not-for-profit group to manage all American science on the station which does notrelate to manned exploration. The module houses 24 International Standard Payload Racks, some ofwhich are used for environmental systems and crew daily living equipment. Destinyalso serves as the mounting point for the stations Truss Structure. Blue EVA hatches in the Pirs airlock frame cosmonaut Thomas Reiter (left), is attired in a liquid cooling and Maxim Suraev Flight engineer who displays two Orlanventilation garment that complements the EMU style space suits space suit worn by Jeffrey N. Williams in the Quest
AirlockQuest is the only USOS airlock, Quest hosts spacewalks with both United States EMU andRussianOrlan spacesuits. Quest consists of two segments; the equipment lock, that stores spacesuitsand equipment, and the crew lock, from which astronauts can exit into space. This module has aseparately controlled atmosphere. Crew sleep in this module, breathing a low nitrogen mixture the nightbefore scheduled EVAs, to avoid decompression sickness (known as "the bends") in the low pressure suits.Pirs (Russian: Пирс, meaning "pier"), (Russian: Стыковочный отсек), "docking module", SO-1 or DC-1(docking compartment), and Poisk (Russian: ; lit. Search), also known as the Mini-ResearchModule 2 (MRM 2), Малый исследовательский модуль 2, or МИМ 2. Pirs and Poisk are Russianairlock modules. Each of these modules have 2 identical hatches. An outward opening hatch on the MIRspace station failed after it swung open too fast after unlatching, due to a small amount of air pressure remaining in the airlock. A different entry was used, and the hatch repaired. All EVA hatches on the ISSopen inwards and are pressure sealing. Pirs is used to store, service, and refurbish Russian Orlan suitsand provides contingency entry for crew using the slightly bulkier American suits. The outermost dockingports on both airlocks allow docking of Soyuz and Progress spacecraft, and the automatic transfer of propellants to and from storage on the ROS.Harmony, is the second of the stations node modules and the utility hub of the USOS. The modulecontains four racks that provide electrical power, bus electronic data, and acts as a central connectingpoint for several other components via its six Common Berthing Mechanisms (CBMs). The EuropeanColumbus and Japanese Kibō laboratories are permanently berthed to two of the radial ports, the othertwo can used for the HTV. American Shuttle Orbiters docked with the ISS via PMA-2, attached to theforward port. Tranquility is the third and last of the stations U.S. nodes, it contains an additional lifesupport system to recycle waste water for crew use and supplements oxygen generation. Three of thefour berthing locations are not used. One location has the cupola installed, and one has the docking portadapter installed. Not large enough for crew using spacesuits, the airlock The Columbus Module in 2008 on Kibō has an internal sliding drawer for experiments.Columbus, the primary research facility for European payloads aboard the ISS, provides a genericlaboratory as well as facilities specifically designed for biology, biomedical research and fluid physics.Several mounting locations are affixed to the exterior of the module, which provide power and data to
external experiments such as the European Technology Exposure Facility (EuTEF), Solar MonitoringObservatory, Materials International Space Station Experiment, and Atomic Clock Ensemble in Space. A number of expansions are planned for the module to study quantum physics andcosmology. ESA‘sdevelopment of technologies on all the main areas of life support has been ongoing for more than 20years and are/have been used in modules such as Columbus and the ATV. The German AerospaceCenter DLR manages ground control operations for Columbus and the ATV is controlled from the FrenchCNES Toulouse Space Center.Kibō (Japanese: きぼう, "hope") is the largest single ISS module. This laboratory is used to carry outresearch in space medicine, biology, Earth observations, materials production, biotechnology,communications research, and has facilities for growing plants and fish. During August 2011, anobservatory mounted on Kibō, which utilises the ISSs orbital motion to image the whole sky in the X-ray spectrum, detected for the first time the moment a star was swallowed by a black hole. Thelaboratory contains a total of 23 racks, including 10 experiment racks and has a dedicated airlock forexperiments. In a shirt sleeves environment, crew attach an experiment to the sliding drawer within theairlock, close the inner, and then open the outer hatch. By extending the drawer and removing theexperiment using the dedicated robotic arm, payloads are placed on the external platform. The processcan be reversed and repeated quickly, allowing access to maintain external experiments without thedelays caused by EVAs. Only the Russian and Japanese laboratories have this feature. A smallerpressurised module is attached to the top of Kibō, serving as a cargo bay. The dedicated Interorbitalcommunications system allows large amounts of data to be beamed from Kibōs ICS, first to theJapanese KODAMA satellite in geostationary orbit, then to Japanese ground stations. When a directcommunication link is used, contact time between the ISS and a ground station is limited to approximately10 minutes per visible pass. When KODAMA relays data between a LEO spacecraft and a ground station,real-time communications are possible in 60% of the flight path of the spacecraft. Ground staff use tele-present robotics to conduct on-orbit research without crew intervention. The Cupolas design has been compared toDmitri Kondratyev and Paolo Nespoli in the Cupola. Background left to the Millennium Falcon from the motion right, Progress M-09M, Soyuz TMA-20, the Leonardomodule and HTV- picture Star Wars. 2.
Tracy Caldwell Dyson poses for a photo in the Cupola, admiring the view of the Earth.Cupola is a seven window observatory, used to view Earth and docking spacecraft. Its name derives fromthe Italian word cupola, which means "dome". The Cupola project was started by NASA and Boeing, butcancelled due to budget cuts. A barter agreement between NASA and the ESA resulted in the Cupolasdevelopment being resumed in 1998 by the ESA. The module comes equipped with robotic workstationsfor operating the stations main robotic arm and shutters to protect its windows from damage caused bymicrometeorites. It features 7 windows, with a 80-centimetre (31 in) round window, the largest window onthe station. The distinctive design has been compared to the turret of the fictitious Millennium Falcon in the motion picture Star Wars; the original prop lightsaber used by actor Mark Hamill as Luke Skywalker in the 1977 film was flown to the station in 2007, and the Falcon rockets commercial shipsthat come to the station use, are named after the Millennium Falcon itself.Rassvet (Russian: ; lit. "dawn"), also known as the Mini-Research Module 1 (MRM-1)(Russian: Малый исследовательский модуль, МИМ 1) and formerly known as the Docking CargoModule (DCM), is similar in design to the Mir Docking Module launched on STS-74 in 1995. Rassvet isprimarily used for cargo storage and as a docking port for visiting spacecraft. It was flown to the ISSaboard NASAs Space Shuttle Atlantis on the STS-132 mission and connected in May 2010, Rassvet is the only Russian owned module launched by NASA, to repay for the launch of Zarya, which is Russian designed and built, but partially paid for by NASA. Rassvet was launched withthe Russian Nauka Laboratorys Experiments airlock temporarily attached to it, and spare parts for theEuropean Robotic Arm.Leonardo Permanent Multipurpose Module (PMM) The three NASA Space Shuttle MPLM cargocontainers Leonardo, Raffaello and Donatello, were built for NASA in Turin, Italy by Alcatel Alenia Space, now Thales Alenia Space. The MPLMs are provided to the ISS programme by the Italy (independentof Italys role as a member state of ESA) to NASA and are considered to be U.S. elements. In a barteredexchange for providing these containers, the U.S. has given Italy research time aboard the ISS out of the U.S. allotment in addition to that which Italy receives as a member of ESA. The PermanentMultipurpose Module was created by converting Leonardo into a module that could be permanently attached to the station.Scheduled additional modulesNauka (Russian: ; lit. Science), also known as the Multipurpose Laboratory Module (MLM)or FGB-2, (Russian: Многофункциональный лабораторный модуль, or МЛМ), is the major Russian laboratory module. It is scheduled to arrive at the station in 2014 and will replace PIRS. Prior to the
arrival of the Nauka, a progress robot spacecraft will dock with PIRS, depart with that module, and bothwill be discarded. It contains an additional set of life support systems and orientation control. Originally itwould have routed power from the single Science-and-Power Platform, but that single module designchanged over the first ten years of the ISS mission, and the two science modules which attach to Naukavia the Node Module each incorporate their own large solar arrays to power Russian science experimentsin the ROS. Naukas mission has changed over time. During the mid 1990s, it was intended as a backupfor the FGB, and later as a universal docking module (UDM); its docking ports will be able to supportautomatic docking of both space craft, additional modules and fuel transfer. Nauka is a module in the 20ton class and has its own engines. Smaller ISS modules (less than 10 tons) which dock to the ROS donot have engines of their own, but rely for propulsion upon the spaceship that brings them to the station.Zvezda and Zarya, like Nauka, weigh about 20 tons each and are launched by the larger Proton rocketsrather than by Soyuz rockets. They are the only 3 modules on the ISS that contain engines, or navigationcomputers with star, sun and horizon sensors, to enable flight and station-keeping. Nauka will beseparated from the ISS before de-orbit, together with support modules, and become the OPSEK spacestation.Node Module (UM)/(NM) This 4-ton ball shaped module will support the docking of two scientific andpower modules during the final stage of the station assembly and provide the Russian segment additionaldocking ports to receive Soyuz TMA (transportation modified anthropometric) and Progress M spacecraft.NM is to be incorporated into the ISS in 2014. It will be integrated with a special version of the Progresscargo ship and launched by a standard Soyuz rocket. The Progress would use its own propulsion andflight control system to deliver and dock the Node Module to the nadir (Earth-facing) docking port of theNauka MLM/FGB-2 module. One port is equipped with an active hybrid docking port, which enablesdocking with the MLM module. The remaining five ports are passive hybrids, enabling docking of Soyuzand Progress vehicles, as well as heavier modules and future spacecraft with modified docking systems.However more importantly, the node module was conceived to serve as the only permanent element ofthe future Russian successor to the ISS, OPSEK. Equipped with six docking ports, the Node Modulewould serve as a single permanent core of the future station with all other modules coming and going as their life span and mission required. This would be a progression beyond the ISS and Russiasmodular MIR space station, which are in turn more advanced than early monolithic first generationstations such as Skylab, and early Salyut and Almaz stations.Science Power Modules 1 & 2 (NEM-1, NEM-2) (Russian: Научно-Энергетический Модуль-1 и -2)Cancelled componentsThe US Habitation Module would have served as the stations living quarters. Instead, the sleep stations are now spread throughout the station. The US Interim Control Module and ISS Propulsion Module were intended to replace functions of Zvezda in case of a launch failure. TheRussian Universal Docking Module, to which the cancelled Russian Research modules and spacecraft would have docked. The Russian Science Power Platform would have provided the Russian Orbital Segment with a power supply independent of the ITS solar arrays, and twoRussian Research Modules that were planned to be used for scientific research.
Unpressurized elementsISS Truss Components breakdown showing Trusses and all ORUs in situThe ISS features a large number of external components that do not require pressurisation. The largestsuch component is the Integrated Truss Structure (ITS), to which the stations main solar arrays and thermal radiators are mounted. The ITS consists of ten separate segments forming a structure 108.5 m (356 ft) long.The station in its complete form has several smaller external components, such as the six robotic arms, the three External Stowage Platforms (ESPs) and four ExPrESS Logistics Carriers (ELCs). Whilstthese platforms allow experiments (including MISSE, the STP-H3 and the Robotic Refuelling Mission) tobe deployed and conducted in the vacuum of space by providing electricity and processing experimentaldata locally, the platforms primary function is to store Orbital Replacement Units (ORUs). ORUs arespare parts that can be replaced when the item either passes its design life or fails. Examples of ORUsinclude pumps, storage tanks, antennas and battery units. Such units are replaced either by astronautsduring EVA or by robotic arms. While spare parts were routinely transported to and from the station viaSpace Shuttle resupply missions, there was a heavy emphasis on ORU transport once the NASA Shuttle approached retirement. Several shuttle missions were dedicated to the delivery of ORUs,   including STS-129, STS-133 and STS-134. To date only one other mode of transportation ofORUs has been utilised – the Japanese cargo vessel HTV-2 – which delivered an FHRC and CTC-2 via its Exposed Pallet (EP).Construction of the Integrated Truss Structure over New Zealand.
There are also smaller exposure facilities mounted directly to laboratory modules; the JEM Exposed Facility serves as an external porch for the Japanese Experiment Module complex, and a facility onthe European Columbus laboratory provides power and data connections for experiments such as the European Technology Exposure Facility and the Atomic Clock Ensemble in Space. A remote sensing instrument, SAGE III-ISS, is due to be delivered to the station in 2014 aboard a Dragon capsule. The largest such scientific payload externally mounted to the ISS istheAlpha Magnetic Spectrometer (AMS), a particle physics experiment launched on STS-134 in May2011, and mounted externally on the ITS. The AMS measures cosmic rays to look for evidence of dark matter and antimatter.Cranes and robotic armsCanadarm2, the largest robotic arm on the ISS, has a mass of 1,800 kilograms and is used to dock andmanipulate spacecraft and modules on the USOS, and hold crew members and equipment during EVAs. The ROS does not require spacecraft or modules to be manipulated, as all spacecraft andmodules dock automatically, and may be discarded the same way. Crew use the2 Strela (Russian: Стрела; lit. Arrow) cargo cranes during EVAs for moving crew and equipment aroundthe ROS. Each Strela crane has a mass of 45 kg. The Russian and Japanese laboratories both haveairlocks and robotic arms. Commander Volkov stands on Pirs with his back to Dextre, like many of the stations experiments and the Soyuz whilst operating the manual Strela robotic arms, can be operated from Earth and perform craneholding photographer Kononenko. Zarya is seen tasks while the crew sleeps. to the left and Zvezda across the bottom of the image.The Integrated Truss Structure serves as a base for the main remote manipulator system called theMobile Servicing System (MSS). This consists of the Mobile Base System (MBS), the Canadarm2,and Dextre. Dextre is a 1,500 kg agile robotic manipulator with two arms which have 7 degrees ofmovement each, a torso which bends at the waist and rotates at the base, a tool holster, lights andvideo. Staff on earth can operate Dextre via remote control, performing work without crew intervention.The MBS rolls along rails built into some of the ITS segments to allow the arm to reach all parts of the United States segment of the station. The MSS had its reach increased an Orbiter Boom SensorSystem in May 2011, used to inspect tiles on the NASA shuttle, and converted for permanent station use.To gain access to the extreme extents of the Russian Segment the crew also placed a "Power DataGrapple Fixture" to the forward docking section of Zarya, so that the Canadarm2 may inchworm itself onto that point.
The European Robotic Arm, which will service the Russian Orbital Segment, will be launched alongside the Multipurpose Laboratory Module in 2012. The Japanese Experiment Modules Remote Manipulator System (JFM RMS), which services the JEM Exposed Facility, was launched on STS-124 and is attached to the JEM Pressurised Module.Station systemsLife supportMain articles: ISS ECLSS and Chemical oxygen generatorThe critical systems are the atmosphere control system, the water supply system, the food supplyfacilities, the sanitation and hygiene equipment, and fire detection and suppression equipment. TheRussian orbital segments life support systems are contained in the Service Module Zvezda. Some ofthese systems are supplemented by equipment in the USOS. The MLM Nauka laboratory has a completeset of life support systems.Atmospheric control systems The atmosphere on board the ISS is similar to the Earths. Normal air pressure on the ISS is 101.3 kPa (14.7 psi); the same as at sea level on Earth. An Earth-like atmosphere offers benefits forcrew comfort, and is much safer than the alternative, a pure oxygen atmosphere, because of the increased risk of a fire such as that responsible for the deaths of the Apollo 1crew. Earth-like atmospheric conditions have been maintained on all Russian and Soviet spacecraft.Elektron units in the Zvezda service module.The Elektron system aboard Zvezda and a similar system in Destiny generate oxygen aboard the station. The crew has a backup option in the form of bottled oxygen and Solid Fuel Oxygen Generation (SFOG) canisters, a chemical oxygen generator system. Carbon dioxide is removed fromthe 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.Part of the ROS atmosphere control system is the oxygen supply, triple-redundancy is provided by theElektron unit, solid fuel generators, and stored oxygen. The Elektron unit is the primary oxygensupply, O2 and H2 are produced by electrolysis, with the H2 being vented overboard. The 1 kW system
uses approximately 1 litre of water per crew member per day from stored water from Earth, or waterrecycled from other systems. MIR was the first spacecraft to use recycled water for oxygen production.The secondary oxygen supply is provided by burning O2-producing Vika cartridges (see also ISS ECLSS).Each candle takes 5–20 minutes to decompose at 450–500 °C, producing 600 litres of O2. This unit is manually operated.The US orbital segment has redundant supplies of oxygen, from a pressurised storage tank on the Questairlock module delivered in 2001, supplemented ten years later by ESA built Advanced Closed-Loop System (ACLS) in the Tranquility module (Node 3), which produces O2by electrolysis. Hydrogenproduced is combined with carbon dioxide from the cabin atmosphere and converted to water andmethane.FoodSee also: Space foodThe crews of STS-127 and Expedition 20enjoy a meal inside Unity.Most of the food on board is vacuum sealed in plastic bags. Cans are too heavy and expensive totransport, so there are not as many. The preserved food is generally not held in high regard by the crew, and when combined with the reduced sense of taste in a microgravity environment, a great deal ofeffort is made to make the food more palatable. More spices are used than in regular cooking, and thecrew looks forward to the arrival of any ships from Earth, as they bring fresh fruit and vegetables withthem. Care is taken that foods do not create crumbs. Sauces are often used to ensure station equipmentis not contaminated. Each crew member has individual food packages and cooks them using the on-board galley. The galley features two food warmers, a refrigerator added in November 2008, and a water dispenser that provides both heated and unheated water. Drinks are provided in dehydrated powder form and are mixed with water before consumption. Drinks and soups are sipped from plastic bagswith straws, while solid food is eaten with a knife and fork, which are attached to a tray with magnets toprevent them from floating away. Any food that does float away, including crumbs, must be collected to prevent it from clogging up the stations air filters and other equipment.Hygiene :139Showers on space stations were introduced in the early 1970s on Skylab and Salyut 3. By Salyut 6,in the early 1980s, the crew complained of the complexity of showering in space, which was a monthlyactivity. The ISS does not feature a shower; instead, crewmembers wash using a water jet and wet wipes,
with soap dispensed from a toothpaste tube-like container. Crews are also provided with rinseless shampoo and edible toothpaste to save water.There are two space toilets on the ISS, both of Russian design, located in Zvezda and Tranquility. These Waste and Hygiene Compartments use a fan-driven suction systemsimilar to the Space Shuttle Waste Collection System. Astronauts first fasten themselves to the toilet seat, which is equipped with spring-loaded restraining bars to ensure a good seal. A lever operates apowerful fan and a suction hole slides open: the air stream carries the waste away. Solid waste iscollected in individual bags which are stored in an aluminium container. Full containers are transferred to Progress spacecraft for disposal. Liquid waste is evacuated by a hose connected to the front of thetoilet, with anatomically correct "urine funnel adapters" attached to the tube so both men and women canuse the same toilet. Waste is collected and transferred to the Water Recovery System, where it is recycled back into drinking water.Power and thermal controlMain articles: Electrical system of the International Space Station and External Active Thermal ControlSystem Russian solar arrays, backlit by sunset. One of the eight truss mounted pairs of USOS solar arraysDouble-sided solar, or Photovoltaic arrays, provide electrical power for the ISS. These bifacial cells aremore efficient and operate at a lower temperature than single-sided cells commonly used on Earth, by collecting sunlight on one side and light reflected off the Earth on the other.The Russian segment of the station, like the Space Shuttle and most spacecraft, uses 28 volt DC fromfour rotating solar arrays mounted on Zarya and Zvezda. The USOS uses 130–180 V DC from the USOSPV array, power is stabilised and distributed at 160 V DC and converted to the user-required 124 V DC.The higher distribution voltageallows smaller, lighter conductors, at the expense of crew safety. The ROS uses low voltage. The two station segments share power with converters.The USOS solar arrays are arranged as four wing pairs, with each wing producing nearly 32.8 kW. These arrays normally track the sun to maximise power generation. Each array is about 2 2375 m (450 yd ) in area and 58 metres (63 yd) long. In the complete configuration, the solar arrays trackthe sun by rotating the alpha gimbal once per orbit while the beta gimbal follows slower changes in theangle 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 stations relatively low orbital altitude.
The station uses rechargeable nickel-hydrogen batteries (NiH2) for continuous power during the 35minutes of every 90 minute orbit that it is eclipsed by the Earth. The batteries are recharged on the dayside of the Earth. They have a 6.5 year lifetime (over 37,000 charge/discharge cycles) and will be regularly replaced over the anticipated 20-year life of the station.The stations large solar panels generate a high potential voltage difference between the station and theionosphere. This could cause arcing through insulating surfaces and sputtering of conductive surfaces asions 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.ISS External Active Thermal Control System (EATCS) diagramThe large amount of electrical power consumed by the stations systems and experiments is turnedalmost entirely into heat. The heat which can be dissipated through the walls of the stations modules isinsufficient to keep the internal ambient temperature within comfortable, workable limits.Ammonia iscontinuously pumped through pipework throughout the station to collect heat, and then into externalradiators exposed to the cold of space, and back into the station.The International Space Station (ISS) External Active Thermal Control System (EATCS) maintains anequilibrium when the ISS environment or heat loads exceed the capabilities of the Passive ThermalControl System (PTCS). Note Elements of the PTCS are external surface materials, insulation such asMLI, or Heat Pipes. The EATCS provides heat rejection capabilities for all the US pressurised modules,including the JEM and COF as well as the main power distribution electronics of the S0, S1 and P1Trusses. The EATCS consists of two independent Loops (Loop A & Loop B), they both use mechanicallypumped Ammonia in fluid state, in closed-loop circuits. The EATCS is capable of rejecting up to 70 kW,and provides a substantial upgrade in heat rejection capacity from the 14 kW capability of the EarlyExternal Active Thermal Control System (EEATCS) via the Early Ammonia Servicer (EAS), which was launched on STS-105 and installed onto the P6 Truss.Communications and computersMain articles: Tracking and Data Relay Satellite and Luch (satellite)See also: ThinkPad use in space
The communications systems used by the ISS* Luch satellite not currently in useRadio communications provide telemetry and scientific data links between the station and Mission ControlCentres. Radio links are also used during rendezvous and docking procedures and for audio and videocommunication between crewmembers, flight controllers and family members. As a result, the ISS is equipped with internal and external communication systems used for different purposes.The Russian Orbital Segment communicates directly with the ground via the Lira antenna mounted to Zvezda. The Lira antenna also has the capability to use the Luch data relay satellite system. This system, used for communications with Mir, fell into disrepair during the 1990s, and as a result is no longer in use, although two new Luch satellites—Luch-5A and Luch-5B—are planned for launch in 2011 to restore the operational capability of the system. Another Russiancommunications system is the Voskhod-M, which enables internal telephone communicationsbetween Zvezda, Zarya, Pirs, Poisk and the USOS, and also provides a VHF radio link to ground control centres via antennas on Zvezdas exterior.The US Orbital Segment (USOS) makes use of two separate radio links mounted in the Z1 trussstructure: the S band (used for audio) and Ku band (used for audio, video and data) systems. Thesetransmissions are routed via the United States Tracking and Data Relay Satellite System (TDRSS)in geostationary orbit, which allows for almost continuous real-time communications with NASAs Mission Control Center (MCC-H) in Houston. Data channels for the Canadarm2,European Columbus laboratory and Japanese Kibōmodules are routed via the S band and K u bandsystems, although the European Data Relay Satellite System and a similar Japanese system will
eventually complement the TDRSS in this role. Communications between modules are carried on an internal digitalwireless network.Laptop computers surround the Canadarm2 console.UHF radio is used by astronauts and cosmonauts conducting EVAs. UHF is employed by otherspacecraft that dock to or undock from the station, such as Soyuz, Progress, HTV, ATV and the SpaceShuttle (except the shuttle also makes use of the S band and K u band systems via TDRSS), to receive commands from Mission Control and ISS crewmembers. Automated spacecraft are fitted with their owncommunications equipment; the ATV uses a laser attached to the spacecraft and equipment attached to Zvezda, known as the Proximity Communications Equipment, to accurately dock to the station.The ISS is equipped with approximately 100 IBM and Lenovo ThinkPad model A31 and T61P laptopcomputers. Each computer is a commercial off-the-shelf purchase which is then modified for safety andoperation including updates to connectors, cooling and power to accommodate the stations 28V DCpower system and weightless environment. Heat generated by the laptops doesnt rise, but stagnatessurrounding the laptop, so additional forced ventilation is required. Laptops aboard the ISS are connectedto the stations wireless LAN via Wi-Fi and are connected to the ground at 3 Mbit/s up and 10 Mbit/s down, comparable to home DSL connection speeds.
Expeditions and private flightsSoyuz TM-31 being prepared to bring the first resident crew to the station in October 2000See also the list of professional crew, private travellers, or bothThe station crew "are our representatives spearheading humanitys exploration of new spaces and possibilities for our future" according to Pope Benedict XVI. Each permanent crew is given anexpedition number. Expeditions run up to six months, from launch until undocking, an increment coversthe same time period, but includes cargo ships and all activities. Expeditions 1 to 6 consisted of 3 personcrews, 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. Withthe arrival of the American Commercial Crew vehicles in the middle of the 2010s, expedition size may be increased to seven crew members, the number ISS is designed for.Sergei Krikalev, member of Expedition 1 and Commander of Expedition 11 has spent more time in spacethan anyone else, a total of 803 days and 9 hours and 39 minutes. His awards include the Order ofLenin, Hero of the Soviet Union, Hero of the Russian Federation, and 4 NASA medals. On 16 August2005 at 1:44 am EDT he passed the record of 748 days held by Sergei Avdeyev, who had time travelled 1/50th of a second into the future on board MIR. He participated in psychosocial experimentSFINCSS-99 (Simulation of Flight of International Crew on Space Station), which examined inter-culturaland other stress factors effecting integration of crew in preparation for the ISS spaceflights.Commander Michael Fincke is the U.S. space endurance record holder with a total of 382 days.Travelers who pay for their own passage into space are called spaceflight participants by the RSA and [note 1]NASA, and are sometimes referred to as space tourists, a term they generally dislike. All seven weretransported to the ISS on Russian Soyuz spacecraft. When professional crews change over in numbersnot divisible by the three seats in a Soyuz, and a short-stay crewmember is not sent, the spare seat issold by MirCorp through Space Adventures. When the space shuttle retired in 2011, and the stationscrew size was reduced to 6, space tourism was halted, as the partners relied on Russian transport seatsfor access to the station. Soyuz flight schedules increase after 2013, allowing 5 Soyuz flights (15 seats) with only two expeditions (12 seats) required. The remaining seats are sold for around US$40 millionto members of the public who can pass a medical. ESA and NASA criticised private spaceflight at thebeginning of the ISS, and NASA initially resisted training Dennis Tito, the first man to pay for his own [note 2]passage to the ISS. Toyohiro Akiyama was flown to Mir for a week, he was classed as a businesstraveller, as his employer, Tokyo Broadcasting System, paid for his ticket, and he gave a daily TVbroadcast from orbit.
Anousheh Ansari (Persian: ) became the first Iranian in space and the first self-funded womanto 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." Ansari herself dismisses the idea thatshe is a tourist. She did Russian and European studies involving medicine and microbiology during her 10day stay. The documentary Space Tourists follows her journey to the station, where she fulfilled the childhood dream to leave our planet as a normal person and travel into outer space. In the film, someKazakhs are shown waiting in the middle of the steppes for four rocket stages to literally fall from the sky.Film-maker Christian Frei states "Filming the work of the Kazakh scrap metal collectors was anything buteasy. The Russian authorities finally gave us a film permit in principle, but they imposed cripplingpreconditions on our activities. The real daily routine of the scrap metal collectors could definitely not beshown. Secret service agents and military personnel dressed in overalls and helmets were willing to re-enact their work for the cameras – in an idealised way that officials in Moscow deemed to be presentable,but not at all how it takes place in reality."Crew activitiesNASA astronaut Scott Kelly works on theCombustion Integrated Rack in the Destiny laboratory.A typical day for the crew begins with a wake-up at 06:00, followed by post-sleep activities and a morninginspection of the station. The crew then eats breakfast and takes part in a daily planning conference withMission Control before starting work at around 08:10. The first scheduled exercise of the day follows,after which the crew continues work until 13:05. Following a one-hour lunch break, the afternoon consistsof more exercise and work before the crew carries out its pre-sleep activities beginning at 19:30, includingdinner and a crew conference. The scheduled sleep period begins at 21:30. In general, the crew worksten hours per day on a weekday, and five hours on Saturdays, with the rest of the time their own for relaxation or work catch-up.The station provides crew quarters for each member of the expeditions crew, with two sleep stations in the Zvezda and four more installed inHarmony. The American quarters are private, approximatelyperson-sized soundproof booths. The Russian crew quarters include a small window, but do not providethe same amount of ventilation or block the same amount of noise as their American counterparts. Acrewmember can sleep in a crew quarter in a tethered sleeping bag, listen to music, use a laptop, andstore personal items in a large drawer or in nets attached to the modules walls. The module also provides a reading lamp, a shelf and a desktop. Visiting crews have no allocated sleep module, andattach a sleeping bag to an available space on a wall—it is possible to sleep floating freely through the station, but this is generally avoided because of the possibility of bumping into sensitive equipment. It
is important that crew accommodations be well ventilated; otherwise, astronauts can wake up oxygen-deprived and gasping for air, because a bubble of their own exhaled carbon dioxide has formed around their heads.Orbit and mission control Graph showing the changing altitude of the ISS from November Animation of ISS orbit from a North American 1998 until January 2009 geostationary point of view (sped up 1800 times)The ISS is maintained in a nearly circular orbit with a minimum mean altitude of 330 km (205 mi) and amaximum of 410 km (255 mi), in the centre of the Thermosphere, at an inclination of 51.6 degrees toEarths equator, necessary to ensure that Russian Soyuz and Progress spacecraft launched fromthe Baikonur Cosmodrome may be safely launched to reach the station. Spent rocket stages must bedropped into uninhabited areas and this limits the directions rockets can be launched from the spaceport. The orbital inclination chosen was also low enough to allow American space shuttleslaunched from Florida to reach the ISS.It travels at an average speed of 27,724 kilometres (17,227 mi) per hour, and completes 15.7 orbits per day. The stations altitude was allowed to fall around the time of each NASA shuttle mission. Orbitalboost burns would generally be delayed until after the shuttles departure. This allowed shuttle payloadsto be lifted with the stations engines during the routine firings, rather than have the shuttle lift itself andthe payload together to a higher orbit. This trade-off allowed heavier loads to be transferred to the station.After the retirement of the NASA shuttle, the nominal orbit of the space station was raised in altitude. Other, more frequent supply ships do not require this adjustment as they are substantially lighter vehicles.Orbital boosting can be performed by the stations two main engines on the Zvezda service module, orRussian or European spacecraft docked to Zvezdas aft port. The ATV has been designed with thepossibility of adding a second docking port to its other end, allowing it to remain at the ISS and still allowother craft to dock and boost the station. It takes approximately two orbits (three hours) for the boost to a higher altitude to be completed. In December 2008 NASA signed an agreement with the Ad AstraRocket Company which may result in the testing on the ISS of aVASIMR plasma propulsion engine. This technology could allow station-keeping to be done more economically than at present.
The Russian Orbital Segment contains the stations engines and control bridge, which handles Guidance, Navigation and Control (ROS GNC) for the entire station. 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. Using two fault-tolerant computers (FTC), Zvezda computes the stations position and orbital trajectory using redundantEarth horizon sensors, Solar horizon sensors as well as Sun and star trackers. The FTCs each containthree identical processing units working in parallel and provide advanced fault-masking by majority voting.Zvezda uses gyroscopes and thrusters to turn itself around. Gyroscopes dont need propellant, ratherthey use electricity to store momentum in flywheels by turning in the opposite direction to the stationsmovement. The USOS has its own computer controlled gyroscopes to handle the extra mass of thatsection. When gyroscopes saturate, reaching their maximum speed, thrusters are used to cancel out thestored momentum. During Expedition 10, an incorrect command was sent to the stations computer, usingabout 14 kilograms of propellant before the fault was noticed and fixed. When attitude control computersin the ROS and USOS dont communicate properly, it can result in a rare force fight where the ROS GNC computer must ignore the USOS counterpart, which has no thrusters. When an ATV, NasaShuttle, or Soyuz is docked to the station, it can also be used to maintain station attitude such as fortroubleshooting. Shuttle control was used exclusively during installation of the S3/S4 truss, which provides electrical power and data interfaces for the stations electronics.Space centres involved with the ISS programmeThe components of the ISS are operated and monitored by their respective space agencies at missioncontrol centres across the globe, including: