The ISS is a joint project among the space agencies of the United States (NASA), Russia (RKA), Japan (JAXA), Canada (CSA) and eleven European countries (ESA). The Brazilian Space Agency (AEB, Brazil) participates through a separate contract with NASA. The Italian Space Agency similarly has separate contracts for various activities not done in the framework of ESA's ISS works (where Italy also fully participates). China has reportedly expressed interest in the project, especially if it is able to work with the RKA, though it is not currently involved.
The ISS is a continuation of several other previously planned space stations: Russia's Mir 2, the U.S. Space Station Freedom, the European Columbus, and Kibo, the Japanese Experiment Module. The projected completion date is 2010, with the station remaining in operation at least until 2016. As of 2008, the ISS is larger than any previous space station.
The ISS has been continuously staffed since the first resident crew entered the station on November 2 2000, thereby providing a permanent human presence in space. The crew of Expedition 17 are currently aboard. At present the station has a capacity for a crew of three. In order to fulfill an active research program it will eventually hold 6 crew members. Early crew members all came from the Russian and U.S. space programs. German ESA astronaut Thomas Reiter joined the Expedition 13 crew in July 2006, becoming the first crew member from another space agency. The station has, however, been visited by astronauts from 16 countries. The ISS was also the destination of the first five space tourists.
The station is serviced primarily by Russian Soyuz and Progress spacecraft and by U.S. Space Shuttle orbiters. On March 9 2008, the European Space Agency ESA launched an Ariane 5 with the first Automated Transfer Vehicle, Jules Verne, toward the ISS carrying over 8,000 kilograms of cargo. Successful docking took place at 14:40 GMT on April 3 2008.
In 2001, the station received the Prince of Asturias Award for International Cooperation.
In the early 1980s, NASA planned Space Station Freedom as a counterpart to the Soviet Salyut and Mir space stations. It never left the drawing board and, with the end of the Soviet Union and the Cold War, it was cancelled. The end of the space race prompted the U.S. administration officials to start negotiations with international partners Europe, Russia, Japan and Canada in the early 1990s in order to build a truly international space station. This project was first announced in 1993 and was called Space Station Alpha. It was planned to combine the proposed space stations of all participating space agencies: NASA's Space Station Freedom, Russia's Mir-2 (the successor to the Mir Space Station, the core of which is now Zvezda) and ESA's Columbus that was planned to be a stand-alone spacelab.
The first section, the Zarya Functional Cargo Block, was put in orbit in November 1998 on a Russian Proton rocket. Two further pieces (the Unity Module and Zvezda service module) were added before the first crew, Expedition 1, was sent. Expedition 1 docked to the ISS on November 2, 2000, and consisted of two Russian cosmonauts, Yuri Gidzenko and Sergei Krikalev, and U.S. astronaut William Shepherd.
The assembly of the International Space Station is a major aerospace engineering endeavor. When assembly is complete the ISS will have a pressurized volume of approximately 1,000 cubic meters. Assembly began in November 1998 with the launch of Zarya – the first ISS module – on a Proton rocket, and as of July 2008 assembly is about 85% complete.
Two weeks after Zarya was launched, the STS-88 shuttle mission followed, bringing Unity, the first of three node modules, and connecting it to Zarya. This bare 2-module core of the ISS remained unmanned for the next one and a half years, until in July 2000 the Russian module Zvezda was added, allowing a maximum crew of three astronauts or cosmonauts to be on the ISS permanently.
|For more information about the modules, visit the module pages linked on the table below.|
|Module||Launch date||Launch vehicle||Docking date||Mass||Assembly flight||Purpose||Isolated View||Station View|
|1998-11-20||Proton-K||N/A||1A/R||Provided electrical power, storage, propulsion, and guidance during initial assembly, now serves as a storage module (both inside the pressurized section and in the externally mounted fuel tanks).|
|1998-12-04||Space Shuttle Endeavour, STS-88||1998-12-07||2A||First American node, connecting the American section of the station to the Russian section (via PMA-1). Provides berthing locations for the Z1 truss, Quest airlock, Destiny laboratory and Node 3.|
|2000-07-12||Proton-K||2000-07-26||1R||Station service module, providing main living quarters for resident crews, environmental systems and attitude & orbit control, in addition to docking locations for Soyuz spacecraft, Progress spacecraft and the Automated Transfer Vehicle. The addition of the module rendered the ISS permanently habitable for the first time.|
|2001-02-07||Space Shuttle Atlantis, STS-98||2001-02-10||5A||Primary research facility for American payloads aboard the ISS, also providing environmental systems and living quarters to the station.|
|2001-07-12||Space Shuttle Atlantis, STS-104||2001-07-14||7A||Primary airlock for the ISS, hosting spacewalks with both American EMU and Russian Orlan spacesuits.|
|2001-09-14||Soyuz-U||2001-09-16||4R||Provides the ISS with additional docking ports for Soyuz & Progress spacecraft, and allows egress and ingress for spacewalks by cosmonauts using Russian Orlan spacesuits, in addition to providing storage space for these spacesuits.|
|2007-10-23||Space Shuttle Discovery, STS-120||2007-11-14||10A||The "utility hub" of the ISS. Node 2 contains four racks that provide electrical power, bus electronic data, and act as a central connecting point for several other components via its six Common Berthing Mechanisms (CBMs). The European Columbus and Japanese Kibō laboratories are currently berthed to Harmony. In addition, the Harmony module serves as a berthing port for the Multi-Purpose Logistics Modules during space shuttle logistics flights.|
|2008-02-07||Space Shuttle Atlantis, STS-122||2008-02-11||1E||Primary research facility for European payloads aboard the ISS, providing ten International Standard Payload Racks and mounting locations for external experiments.|
| Experiment Logistics Module|
|2008-03-11||Space Shuttle Endeavour, STS-123||2008-03-12||1J/A||Part of the Kibō Japanese Experiment Module laboratory, the ELM provides storage and transportation facilities to the laboratory, with a pressurized section to serve internal payloads and an unpressurized section to serve external payloads.|
| Japanese Pressurized Module|
|2008-05-31||Space Shuttle Discovery, STS-124||2008-06-03||1J||Part of the Kibō Japanese Experiment Module laboratory, the PM is the core module of Kibō to which the ELM & Exposed Facility are berthed. The laboratory is the largest single ISS module, and contains ten International Standard Payload Racks.|
|Mini-Research Module 2||2009-08-15||Soyuz-U||TBD||5R||Not yet launched. The newest Russian component of the ISS, MRM2 will likely be used for docking and cargo storage aboard the station.|
|Node 3||2010-03-18||Space Shuttle Discovery, STS-132||TBD||20A||Not yet launched. The last of the station's US nodes, Node 3 will contain an advanced life support system to recycle waste water for crew use and generate oxygen for the crew to breathe. The node also provides four berthing locations for more attached pressurized modules or crew transportation vehicles, in addition to the permanent berthing location for the station's Cupola.|
|Cupola||2010-03-18||Space Shuttle Discovery, STS-132||TBD||20A||Not yet launched. The Cupola is an observatory module that will provide ISS crew members with a direct view of robotic operations and docked spacecraft, as well as an observation point for watching the Earth. The module will come equipped with robotic workstations for operating the SSRMS and shutters to prevent its windows from being damaged by micrometeorites.|
|Mini-Research Module 1||2010-03-18||Space Shuttle Atlantis, STS-131||TBD||ULF4||Not yet launched. MRM1 will be used for docking and cargo storage aboard the station.|
|Multipurpose Laboratory Module||December 2011||Proton-K||TBD||3R||Not yet launched. The MLM will be Russia's primary research module as part of the ISS, and will be used for experiments, docking and cargo logistics. It will also serve as a crew work and rest area, and will also be equipped with a backup attitude control system that can be used to control the station's attitude.|
Using a high-voltage (130 to 160 volts) distribution line in the U.S. part of the station allows smaller power lines and less weight.
The solar array normally tracks the Sun to maximize the amount of solar power. The array is about 375 m² in area and long. In the fully-complete configuration, the solar arrays track the sun in each orbit by rotating the alpha gimbal; while the beta gimbal adjusts for the angle of the sun from the orbital plane. (until the main truss structure arrived, the arrays were in a temporary position perpendicular to the final orientation, and in this configuration, as shown in the image to the right, the beta gimbal was used for the main solar tracking.) Another slightly different tracking option, Night Glider mode, can be used to reduce the drag slightly by orienting the solar arrays edgewise to the velocity vector.
The ISS Environmental Control and Life Support System provides or controls elements such as atmospheric pressure, oxygen levels, water, and fire extinguishing, among other things. The Elektron system generates oxygen aboard the station. The highest priority for the life support system is the ISS atmosphere, but the system also collects, processes, and stores waste and water produced and used by the crew. For example, the system recycles fluid from the sink, shower, urine, and condensation. Activated charcoal filters are the primary method for removing byproducts of human metabolism from the air.
One of the main goals of the ISS is to provide a place to conduct experiments that require one or more of the unusual conditions present on the station. The main fields of research include biology (including biomedical research and biotechnology), physics (including fluid physics, materials science, and quantum physics), astronomy (including cosmology), and meteorology. The 2005 NASA Authorization Act designated the U.S segment of the International Space Station as a national laboratory with a goal to increase the utilization of the ISS by other Federal entities and the private sector. As of 2007, little experimentation other than the study of the long-term effects of microgravity on humans has taken place. With four new research modules set to arrive at the ISS by 2010, however, more specialized research is expected to begin.
The Destiny Laboratory Module is the main research facility currently aboard the ISS. Produced by NASA and launched in February 2001, it is a research facility for general experiments. The Columbus module is another research facility, designed by the ESA for the ISS. Its purpose is to facilitate scientific experiments and was launched on February 2008. It should provide a generic laboratory as well as ones specifically designed for biology, biomedical research and fluid physics. There are also a number of planned expansions that will be implemented to study quantum physics and cosmology. The Japanese Experiment Module, also known as Kibō, was put in service during STS-124 on June 3, 2008. It was developed by JAXA in order to function as an observatory and to measure various astronomical data. The ExPRESS Logistics Carrier, developed by NASA, is set to be launched for the ISS with the STS-129 mission, which is expected to take place no earlier than September 11, 2009. It will allow experiments to be deployed and conducted in the vacuum of space and will provide the necessary electricity and computing to locally process data from experiments. The Multipurpose Laboratory Module, created by the RKA, is expected to launch for the ISS in December 2011. It will supply the proper resources for general microgravity experiments.
Several planned research modules have been cancelled, including the Centrifuge Accommodations Module (used to produce varying levels of artificial gravity) and the Russian Research Module (used for general experimentation).
NASA would also like to study prominent problems in physics. The physics of fluids in microgravity are not completely understood, and researchers would like to be able to accurately model fluids in the future. Additionally, since fluids in space can be combined nearly completely regardless of their relative weights, there is some interest in investigating the combination of fluids that would not mix well on Earth. By examining reactions that are slowed down by low gravity and temperatures, scientists also hope to gain new insight concerning states of matter (specifically in regards to superconductivity).
Additionally, researchers hope to examine combustion in the presence of less gravity than on Earth. Any findings involving the efficiency of the burning or the creation of byproducts could improve the process of energy production, which would be of economic and environmental interest. Scientists plan to use the ISS to examine aerosols, ozone, water vapor, and oxides in Earth's atmosphere as well as cosmic rays, cosmic dust, anti-matter, and dark matter in the Universe.
The long-term goals of this research are to develop the technology necessary for human-based space and planetary exploration and colonization (including life support systems, safety precautions, environmental monitoring in space), new ways to treat diseases, more efficient methods of producing materials, more accurate measurements than would be impossible to achieve on Earth, and a more complete understanding of the Universe.
However, in an internal e-mail sent 18 August, 2008 to NASA managers (published 6 September, 2008 in the Orlando Sentinel), Griffin flatly stated his belief that the current US administration has made no viable plan for US crews to participate in the ISS beyond 2011, and that OMB and OSTP are actually seeking its demise. Griffin believes the only reasonable solution is to extend the operation of the Space Shuttle beyond 2010, but notes that Executive Policy (ie, the White House) is firm that there will be no extension of the shuttle retirement date, and thus no US capability to launch crews into orbit until the Ares I/Orion system becomes operational in 2014 at the very earliest. He does not see purchase of Russian launches for NASA crews as politically viable following the 2008 South Ossetia war, and hopes the new US administration will resolve the issue in 2009 by extending shuttle operations beyond 2010.
The crew initially reported smoke in the cabin, as well as a smell. It was later found to be caused by a leak of potassium hydroxide from an oxygen vent. The equipment was turned off. Potassium hydroxide is odorless and the smell reported by Williams more likely was associated with an overheated rubber gasket in the Elektron system.
In any case, the station's ventilation system was shut down to prevent the spread of smoke or contaminants through the rest of the lab complex. A charcoal air filter was put in place to help scrub the atmosphere of any lingering potassium hydroxide fumes. The space station's program manager said the crew never donned gas masks, but as a precaution put on surgical gloves and masks to prevent contact with any contaminants.
By June 15, the primary Russian computers were back online, and talking to the US side of the station by bypassing a circuit. Secondary systems were still offline, and further work was needed. NASA reported that without the computer that controls the oxygen levels, the station had 56 days of oxygen available.
By the afternoon of June 16, ISS Program Manager Michael Suffredini confirmed that all six computers governing command and navigation systems for Russian segments of the station, including two thought to have failed, were back online, and would be tested over several days. The cooling system was the first system brought back online. NASA suggested that the overcurrent protection circuits designed to safeguard each computer from power spikes were at fault, and may have been tripped due to increased interference, or "noise," from the station's plasma environment related to the addition of the new starboard trusses and solar arrays. Troubleshooting of the failure by the ISS crew found that the root cause was condensation inside the electrical connectors, leading to a short-circuit that triggered the "power off" command line leading to all three of the redundant processing units. This was initially a concern, because the European Space Agency uses the same computer systems, supplied by EADS Astrium Space Transportation, for the Columbus Laboratory Module and the Automated Transfer Vehicle. Once the root cause was understood, plans were implemented to avoid the problem in the future.
A second, smaller tear was noticed upon further inspection, and the mission's planned spacewalks were completely replanned in mere days to devise a repair. On Saturday November 3, spacewalker Scott Parazynski assisted by Douglas Wheelock fixed the torn panels using makeshift "cufflinks" and riding on the end of the space shuttle's boom inspection arm; the first ever spacewalker to do so. The spacewalk was regarded as significantly more dangerous than most due to the possibility of shock from the electricity generating solar arrays, the unprecedented usage of the shuttle boom arm, and the lack of spacewalk planning and training for the impromptu procedure. Parazynski was, however, able to repair the damage as planned and the repaired array was fully deployed.
On September 25, 2008, NASA announced significant progress in diagnosing the source of the starboard SARJ problem, and a program to repair it on orbit, beginning with the upcoming STS-126 (Endeavour ) flight, currently expected no earlier than November 16, 2008. STS-126 will be a 15-day mission with four EVAs, largely dedicated to servicing and repair of the Solar Alpha Rotary Joints, plus station logistics and resupply. Both the starboard and port SARJs will be serviced. In addition to lubricating both bearings, the remaining 11 Trundle Bearings in the right SARJ will be replaced.
On January 30 2008, NASA announced that another problem, also on the starboard array side, is believed to have been rectified with the replacement of the Bearing Motor Roll Ring Module (BMRRM) in the Beta Gimbal Assembly (BGA) 1A.
An additional spacecraft, the K-1 Vehicle manufactured by Rocketplane Kistler, was proposed as part of the NASA Commercial Orbital Transportation Services program, and was scheduled to fly in 2009. On October 18 2007, NASA discontinued its agreement with Rocketplane Kistler after the company couldn't secure further financing and didn't meet a critical design review for the pressurized cargo module. NASA then announced that the remaining $175 million commitment to the project would be made available to other companies. On 19 February 2008, NASA awarded Orbital Sciences Corporation with the remaining $170 million to develop its Cygnus spacecraft for the COTS program.
The International Space Station is the most-visited spacecraft in the history of space flight. As of April 11, 2008, it has had 213 (non-distinct) visitors. Mir had 137 (non-distinct) visitors (See Space station). The number of distinct visitors of the ISS is 158 (see list of International Space Station visitors).
The legal structure that regulates the space station is multi-layered. The primary layer establishing obligations and rights between the ISS partners is the Space Station Intergovernmental Agreement (IGA), an international treaty signed on January 28 1998 by fifteen governments involved in the Space Station project. The ISS consists of Canada, Japan, the Russian Federation, the United States, and eleven Member States of the European Space Agency (Belgium, Denmark, France, Germany, Italy, The Netherlands, Norway, Spain, Sweden, Switzerland and the United Kingdom). Article 1 outlines its purpose:
This Agreement is a long term international co-operative framework on the basis of genuine partnership, for the detailed design, development, operation, and utilisation of a permanently inhabited civil Space Station for peaceful purposes, in accordance with international law.
The IGA sets the stage for a second layer of agreements between the partners referred to as 'Memoranda of Understanding' (MOUs), of which four exist between NASA and each of the four other partners. There are no MOUs between ESA, Roskosmos, CSA and JAXA due to the fact that NASA is the designated manager of the ISS. The MOUs are used to describe the roles and responsibilities of the partners in more detail.
A third layer consists of bartered contractual agreements or the trading of the partners' rights and duties, including the 2005 commercial framework agreement between NASA and Roskosmos that sets forth the terms and conditions under which NASA purchases seats on Soyuz crew transporters and cargo capacity on unmanned Progress transporters.
A fourth legal layer of agreements implements and supplements the four MOUs further. Notably among them is the ISS code of conduct, setting out criminal jurisdiction, anti-harassment and certain other behavior rules for ISS crewmembers.
There is no fixed percentage of ownership for the whole space station. Rather, Article 5 of the IGA sets forth that each partner shall retain jurisdiction and control over the elements it registers and over personnel in or on the Space Station who are its nationals. Therefore, for each ISS module only one partner retains sole ownership. Still, the agreements to use the space station facilities are more complex.
The three planned Russian segments Zvezda, the Multipurpose Laboratory Module and the Docking and Cargo Modules are made and owned by Russia, which, as of today, also retains its current and prospective usage (Zarya, although constructed and launched by Russia, has been paid for and is officially owned by NASA). In order to use the Russian parts of the station, the partners use bilateral agreements (third and fourth layer of the above outlined legal structure). The rest of the station, (the U.S., the European and Japanese pressurized modules as well as the truss and solar panel structure and the two robotic arms) has been agreed to be utilized as follows (% refers to time that each structure may be used by each partner):
The overall majority of costs for NASA are incurred by flight operations and expenses for the overall management of the ISS. Costs for initially building the U.S. portion of the ISS modules and external structure on the ground and construction in space as well as crew and supply flights to the ISS do account for far less than the general operating costs (see annual budget allocation below).
NASA does not include the basic Space Shuttle program costs in the expenses incurred for the ISS program, despite the fact that the Space Shuttle has been nearly exclusively used for ISS construction and supply flights since December 1998.
NASA's 2007 budget request lists costs for the ISS (without Shuttle costs) as $25.6 billion for the years 1994 to 2005. For each of 2005 and 2006 about $1.7 to 1.8 billion are allocated to the ISS program. The annual expenses will increase until 2010 when they will reach $2.3 billion and should then stay at the same level, however inflation-adjusted, until 2016, the defined end of the program. NASA has allocated between $300 and 500 million for program shutdown costs in 2017.
The $1.8 billion expensed in 2005 consisted of:
Only costs for mission and mission integration and launch site processing for the 33 ISS-related Shuttle flights are included in NASA's ISS program costs. Basic costs of the Shuttle program are, as mentioned above, not considered part of the overall ISS costs by NASA, because the Shuttle program is considered an independent program aside from the ISS. Since December 1998 the Shuttle has, however, been used nearly exclusively for ISS flights (since the first ISS flight in December 1998, until October 2007 only 5 flights out of 28 flights have not been to the ISS, and only the planned Hubble Space Telescope servicing mission in 2008 will not be ISS-related out of 13 planned missions until the end of the Space Shuttle program in 2010).
Shuttle program costs during ISS operations from 1999 to 2005 (disregarding the first ISS flight in December 1998) have amounted to approximately $24 billion (1999: $3,028.0 million, 2000: $3,011.2 million, 2001: $3,125.7 million, 2002: $3,278.8 million, 2003: $3,252.8 million, 2004: $3,945.0 million, 2005: $4,319.2 million). In order to derive the ISS-related costs, expenses for non-ISS flights need to be subtracted, which amount to 20% of the total or about $5 billion. For the years 2006-2011 NASA projects another $20.5 billion in Space Shuttle program costs (2006: $4,777.5 million, 2007: $4,056.7 million, 2008: $4,087.3 million, 2009: $3,794.8 million, 2010: $3,651.1 million and 2011: $146.7 million). If the Hubble servicing mission is excluded from those costs, ISS-related costs will be approximately $19 billion for Shuttle flights from 2006 until 2011. In total, ISS-related Space Shuttle program costs will therefore be approximately $38 billion.
There have also been considerable costs for designing Space Station Freedom in the 1980s and early 1990s, before the ISS program started in 1993. Plans of Space Station Freedom were reused for the International Space Station.
To sum up, although the actual costs NASA views as connected to the ISS are only half of the $100 billion figure often cited in the media, if combined with basic program costs for the Shuttle and the design of the ISS' precursor project Space Station Freedom, the costs reach $100 billion for NASA alone.
The ISS has been far more expensive than originally anticipated. The ESA estimates the overall cost from the start of the project in the early 1990s to the prospective end in 2017 to be in the region of €100 billion ($157 billion or £65.3 billion).
The ISS and NASA have been the targets of varied criticism over the years. Critics contend that the time and money spent on the ISS could be better spent on other projects—whether they be robotic spacecraft missions, space exploration, investigations of problems here on Earth, or just tax savings. Some critics, like Robert L. Park, argue that very little scientific research was convincingly planned for the ISS in the first place. They also argue that the primary feature of a space-based laboratory is its microgravity environment, which can usually be studied more cheaply with a "vomit comet" (that is, an aircraft which flies in parabolic arcs.)
Two of the most ambitious ISS projects to date—the Alpha Magnetic Spectrometer and the Centrifuge Accommodations Module—have been cancelled or delayed due to the prohibitive costs NASA faces in simply completing the ISS. As a result, the research done on the ISS is generally limited to experiments which do not require any specialized apparatus. For example, in the first half of 2007, ISS research dealt primarily with human biological responses to being in space, covering topics like kidney stones, circadian rhythm, and the effects of cosmic rays on the nervous system. Critics argue that this research has little practical value, since space exploration is today almost universally done by robots.
Other critics have attacked the ISS on some technical design grounds:
In response to some of these criticisms, advocates of manned space exploration say that criticism of the ISS project is short-sighted, and that manned space research and exploration have produced billions of dollars' worth of tangible benefits to people on Earth. Jerome Schnee estimated that the indirect economic return from spin-offs of human space exploration has been many times the initial public investment. A review of the claims by the Federation of American Scientists argued that NASA's rate of return from spin-offs is actually very low, except for aeronautics work that has led to aircraft sales.
Critics also say that NASA is often casually credited with "spin-offs" (such as Velcro and portable computers) that were developed independently for other reasons. NASA maintains a list of spin-offs from the construction of the ISS, as well as from work performed on the ISS. However, NASA's official list is much narrower and more arcane than dramatic narratives of billions of dollars of spin-offs.
It is therefore debatable whether the ISS, as distinct from the wider space program, will be a major contributor to society. Some advocates argue that apart from its scientific value, it is an important example of international cooperation. Others claim that the ISS is an asset that, if properly leveraged, could allow more economical manned Lunar and Mars missions. Either way, advocates argue that it misses the point to expect a hard financial return from the ISS; rather, it is intended as part of a general expansion of spaceflight capabilities.