International Space Station

There have long been dreams of a permanently inhabited base or station in space. In 1957 it first became possible to put human-made objects into orbit around Earth. But while both the United States and the Soviet Union raced to send a man to the Moon in the 1960s, the goal of a space station in orbit was secondary. It was after the United States won that "space race" in 1969 that both spacefaring countries sought new directions for their human spaceflight programs.

Previous Space Stations

Shortly before the National Aeronautics and Space Administration (NASA) launched the first Moon mission, the agency began focused design work on America's first orbiting laboratory—Skylab—a converted Saturn Moon rocket stage. Only 36 meters (117 feet) long, it did not rotate to create the artificial gravity that physiologists of two decades earlier believed would be required for humans to live in space. Skylab was launched in May 1973 and occupied intermittently over the following five and a half months by three successive three-person crews. Since it was already known that astronauts could survive weightlessness, answering other questions became paramount. There were unlimited questions about how chemistry, physics, biology, and engineering principles worked without gravity, along with a unique vantage for observations of the Sun and Earth. In February 1974, after only 171 days of occupancy, this successful project was ended. NASA had been given a higher priority manned spaceflight project by President Richard M. Nixon: build a reusable spaceship—the space shuttle. Skylab was to be the last U.S. space station project for a decade.

Soon after Apollo 11 ended the Moon race in 1969, the Soviet Union turned its efforts to short-term Earth-orbiting laboratories. The Soviets named their first generation space station Salyut. In April 1971 Salyut 1 was orbited. Two to three cosmonauts, launched to the station in Soyuz spacecraft, lived for weeks in the cylindrical lab/home with a volume half that of the inside of a school bus. The Russians orbited seven successive space stations over a period of eleven years and conducted thirty-eight crewed missions onboard. They were mostly successful. These early Soviet stations were occupied intermittently for increasingly long periods of up to almost eight months. Salyut 7 was still in orbit when a new Soviet space station project began in February 1986 with the launch of the Mir core module.

Mir was the first permanently crewed station designed as an assembly, or complex, of specialized research modules. The five modules were added one at a time through April 1996. Even while beginning the assembly and operation of Mir, the Soviets were planning another Mir-type station—a plan revised because of developments both at home and in the United States.

The Modern Space Station Project

In his State of the Union address before a joint session of the U.S. Congress on January 25, 1984, President Ronald Reagan directed NASA "to develop a permanently manned space station and to do it within a decade." He went on to say that "NASA will invite other countries to participate." So began the International Space Station (ISS) project and, indirectly, the coalescing of Russian and American space station projects.

NASA had pressed the White House and Congress for a permanent space station project since the successful Space Transportation System (space shuttle) flight program began in 1981. Preliminary design studies were already underway when the president made his announcement. Within weeks NASA invited other countries to join the project. Interest was already high at the European Space Agency (ESA), the intergovernmental agency for eleven European countries, with whom the United States had a decade of experience through ESA's contributions to the space shuttle program. The Canadian Space Agency and the National Space Development Agency of Japan were also interested in participating.

There was basic agreement among all space agencies as well as the Congress (now a virtual partner in its role as authorizer of NASA activities and appropriator of funds) that the station was to be modular in construction. The space shuttle was to be the major launcher of components and crew.

In early 1984, the space station concept was an architecture of three elements: a crewed complex with laboratories, a co-orbiting automated science satellite or platform, and another platform in polar orbit. The reference design for the central complex was called the "Power Tower," reflecting its resemblance to that structure. But when technical evaluation revealed a less than adequate microgravity environment for the laboratories, another concept called "Dual-Keel" became the baseline design in 1985. The large squared structure of trusses and beams with the occupied modules at the center of gravity gave this configuration its name. Outrigger-like trusses secured the solar arrays. ESA negotiated a preliminary agreement to contribute a pressurized laboratory module and the polar platform; Japan agreed to provide another laboratory and a cargo carrying module; and Canada would provide a mobile robotic system that would do work along the external structure. By the end of 1986 the space shuttle Challenger accident had enhanced the concern for crew safety, leading to such changes as reduced shuttle flight rates and fewer space walks for construction. A "lifeboat" for emergency crew return was also added to the plans. These changes forced a reduction in size.

In 1988, the international partners signed formal cooperation documents for the space station project, which they agreed would be named "Freedom." Each partner's contribution would be paid for by that partner. In this period the cost of the U.S. portion—the largest share of the project—began to draw the attention of NASA and the U.S. Congress. The initial cost estimate in 1984, just for design, development of new technical hardware and software, manufacture, and preparation for launch, was $8 billion. Five years later the cost estimate, through "assembly complete," had grown to $30 billion. Subsequent cost-containment actions included the indefinite delaying of some structure and power generation features and the dropping of the polar platform from the station project.

As design work progressed fitfully at NASA's design centers and U.S. contractor companies tabulated further increases in estimated total cost, the activities that "Freedom" could support were under almost constant review and change. By 1993 the reductions in station capability compared to its estimated cost forced the cancellation of the "Freedom" design. Very little hardware had been built. As a new design concept was being developed, President Bill Clinton announced that the new space station project would include not only the previous international partners but Russia as well.

Even as the space station Mir continued in operation in space the Soviet government fell in the early 1990s. Soviet plans for a follow-on to Mir were evaporating. Russia joined the U.S. partnership for a new design that was named International Space Station Alpha (ISSA). The next-generation Russian space station elements would be installed as part of the Alpha station, and American astronauts would join cosmonauts onboard the Mir for seven long-duration missions in the mid-1990s. The Russians got their next-generation space station when their collapsing economy could not afford to fund the effort by itself. The United States got early long-duration spaceflight experience—up to six months at a stretch—for its astronauts and ground controllers. Russian design and operational spaceflight experience also became available for a project at least as complex as the Apollo Moon landings.

In late 1993, detailed design of ISSA, later shortened to ISS, was begun, drawing upon 75 percent of the "Freedom" design. This space station looks like a Tinkertoy assembly of one 88-meter-long (290-foot-long) beam, with four wing-like power panels at each end, and a collection of centrally mounted cylinders—the modules. If it could be assembled on the ground it would cover an area as large as two football fields. Its design is refined to provide the lowest possible gravitational disturbances—microgravity—within its four central laboratory modules, while generating power from sunlight that was greater than the energy used in ten average American homes. Initially three and eventually seven international astronauts could work on-board for up to six months before exchanging with the next crew. The volume of space where they lived and worked was about the size of three two-bedroom American homes.

The first module of the ISS was launched by Russia in November 1998. It served as the core for the two U.S. and one Russian modules that followed. Although Russian funding problems and U.S. equipment problems have caused some delays, in mid-2001 the second expedition of three was installed aboard the station, now once again named "Alpha" by the crews. Biotechnology and human biomedical research is being done in the U.S. laboratory module named "Destiny." As more shuttle flights outfit the laboratory and later the European and Japanese laboratories are docked to ISS, research will progressively increase to include science in fundamental biology and physics, fluid physics, combustion science, materials science, technology development, and the earth and space sciences.

Commercial industries of all sorts are being offered a share of the facilities for work on products and services for Earth. Completed assembly and outfitting of the ISS is planned for around 2005, with an operating life of at least ten years. Overall mission control will still be from Houston, Texas, backed up by Moscow, Russia, and with small staffs for routine operations planning and ground control functions. During the space station's operation as a hybrid science laboratory and industrial park in orbit, researchers will conduct most of their work remotely from desktop control stations in their Earth-bound labs or offices. Following experiment setup by a space station crew member, telescience will lead to great efficiencies, allowing the crew to focus on maintenance and hands-on-required research. The ISS has been a world-class challenge and is becoming a world-class facility for twenty-first century innovations in science, technology, and commerce.

SEE ALSO INTERNATIONAL COOPERATION (VOLUME 3); INTERNATIONAL SPACE STATION (VOLUME 1); LEY, WILLY (VOLUME 4); MICROGRAVITY (VOLUME 2); MIR (VOLUME 3); SKYLAB (VOLUME 3); SPACE SHUTTLE (VOLUME 3); SPACE STATIONS OF THE FUTURE (VOLUME 4).

Charles D. Walker

Bibliography

Hall, Rex, ed. The History of Mir, 1986-2000. London: British Interplanetary Society, 2000.

Mark, Hans. The Space Station: A Personal Journey. Durham, NC: Duke University Press, 1987.

National Aeronautics and Space Administration. The International Space Station Fact Book. Washington, DC: Author, 2000.

Newkirk, Dennis. Almanac of Soviet Manned Space Flight. Houston, TX: Gulf Publishing Company, 1990.

Rumerman, Judy A. U.S. Human Spaceflight: A Record of Achievement, 1961-1998. Washington, DC: National Aeronautics and Space Administration, 2000.

Internet Resources

International Space Station. National Aeronautics and Space Administration. <http://spaceflight.nasa.gov/station/index.html>.

Smith, Marcia. NASA's Space Station Program: Evolution and Current Status. Testimony Before the House Science Committee. U.S. Congress. <http://www.house.gov/science/full/apr04/smith.htm>.