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In the first 1946 summary of his work during World War II, Wernher von Braun prophesied the construction of space stations in orbit. The design, a toroidal station spun to provide artificial gravity, would be made very familiar to the American public over the next six years. The design was elaborated at the First Symposium on Space Flight on 12 October 1951 at the Hayden Planetarium in New York City. The design was popularised in the series in Colliers magazine, illustrated with gorgeous Chesley Bonestell painting, in 1953.

In 1954 Ehricke postulated a four-man design that might serve a number of different purposes, depending upon altitude and orbital inclination. Such a station might be used for a multitude of scientific research, for orbital reconnaissance, for an observation platform, and as a launch site for more distant space ventures. The station would be launched initially by a large multistaged booster and subsequently visited by crews and resupplied by means of smaller ferry rockets.

In 1958, the year after Sputnik 1, Krafft Ehricke, then with General Dynamics' Convair Division, designed a four-man space station known as Outpost. Ehricke proposed that the Atlas ICBM being developed by Convair could be adapted as the station's basic structure. The Atlas, 3 m in diameter and 22.8 m long, was America's largest rocket at the time.

In the Project Horizon report, Wernher von Braun, then with the Army Ballistic Missile Agency, advanced a theory that he had conceived years earlier for using a booster's spent stage as a space station's basic structure. This later evolved into the "wet stage" concept for the Skylab Program. Project Horizon envisioned moving quickly to an early improved station constructed from 22 upper stage shells. Prior to any expansion of lunar outpost operations, sufficient tankage would have been placed in orbit to permit construction of two or three such stations. The orbital station crew strength was approximately ten; however, the crew would be rotated every several months.

Designed by Douglas, the Space Vehicle was represented by a full-scale model at the Ideal Home Show in London in 1962. It had a length of 19 m and was 5.2 m in diameter. It was clearly based on the use of a Saturn S-IV spent second stage. After take-off the first stage of the Saturn I would burn out at an altitude of 60 km; the second stage would enter orbit at 400 km. Once in orbit the Space Vehicle was pointed towards the sun. Its mission was to map stellar space, to make spectroscopic observations and to obtain other astronomical data, all of which are telemetered directly to earth stations.

Apollo X was the designation given at various times during the Apollo program for follow-on versions of the spacecraft for extended earth-orbit operations (for a time, all follow-on projects using Apollo hardware were termed 'Apollo X'. Initial studies concentrated on extending the life of the basic Apollo CSM to accomodate missions of up to 100 days. A 1962 design used an adaptation of �existing� Apollo hardware to create a space laboratory. Later variants used various kinds of laboratories within or integrated into the Apollo SLA adapter. Apollo X also covered rather extensive work to give Apollo a land landing capability, using a parawing or retrorockets, so that the vast naval recovery fleet could be dispensed with.

Proposed derivatives of the basic one-crew Mercury capsule for investigation of earth orbit rendezvous, lifting re-entry and land landing. Two-crew derivatives of Mercury, originally designated Mercury Mark II, are covered under 'Gemini'.

Large Orbiting Research Laboratory was a term applied to a number of NASA and USAF designs of the 1960's intended to succeed MORL. Typically these were rotating stations orbited in a single Saturn V launch. NASA finally decided it preferred a large zero-G station, which became the baseline for studies by 1968.

MOL (Manned Orbiting Laboratory) was the US Air Force's manned space project after Dynasoar was cancelled, until it in turn was cancelled in 1969. The earth orbit station used a helium-oxygen atmosphere, a Gemini capsule accomodating a crew of two for ascent and reentry, and the Gemini retrofire package to return the crew to earth. MOL normally would have remained attached to the Titan III transtage, which would provide it up to 760 m/sec of maneuver capability. Experiments planned ranged the gamut from military reconnaisance using large optical cameras and side-looking radar, through interception and inspection of satellites, to exploring the usefulness of man in space and test of Manned Maneuvering Units. After cancellation, some of the reconnaisance systems ended up in later KH series sattelites, and some of the manned experiements were accomplished on Skylab.

In June 1964 Boeing and Douglas received Phase I contracts for Manned Orbital Research Laboratory station designs. The recommended concept was a 13.5 tonne "dry" space station, launched by Saturn IB, with Gemini or Apollo being used for crew rotation. The 6.5 meter diameter and 12.6 meter long station included a docking adapter, hangar section, airlock, and a dual-place centrifuge. Douglas was selected by NASA LaRC for further Phase 2 and 3 studies in 1963 to 1966. Although MORL was NASA's 'baseline station' during this period, it was dropped by the late 1960's in preference to the more capable station that would become Skylab.

During 1962 NASA Centers, the Air Force, and many of the major aerospace contractors were developing possible space station concepts and studying their potential uses. The Air Force recommended concept of the period is shown here. The station would apparently be launched by a member of the USAF Titan vehicle family. The Centaur-derived upper stage is 3.05 m in diameter and is equipped with four RL10 engines. In the artificial-G station concept, the spent stage provides a counterweight to the separate space station module. The zero-G station uses the spent stage concept to outfit the hydrogen tank of the upper stage with a three-story living and working area. The station is launched unmanned. Crews are rotated using a Saturn-I or Titan-3 launched Apollo spacecraft.

Apollo A was a pre-moon landing version of the Apollo spacecraft specifically designed for long-duration operations in space. In the adapter between the Saturn second stage and the Apollo spacecraft, as an integral part, was a section to be used as an orbiting laboratory. Preliminary designs indicated this laboratory would be a cylindrical section about 3.9 m in diameter and 2.4 m in height.

Lockheed made an unsolicited proposal to NASA in 1963 for an ambitious space station project. The elements would be launched by Saturn I, as would the 'Astrocommuter' shuttle. Neither NASA or Lockheed management showed much interest in the concept.

Lockheed proposed a space tug to service its 1963 space station.

The first space station designs using the Saturn V launch vehicle involved spinning stations, providing artificial G for the crew. This resulted in a number of interesting single-launch designs with unfolding station structures. By the mid-1960's these had been abandoned at NASA in favour of zero-G monolithic stations.

In 1964 the MSC Advanced Spacecraft Technology Division formulated a mission flight plan for using a Gemini spacecraft to link up with an orbiting vehicle to achieve a long-duration space mission (dubbed the "Pecan" mission). The two crewmen were to transfer to the Pecan for the duration of the mission.

Wernher von Braun made a rough sketch of a space station based on on fitting out of an expended Saturn II stage in orbit on 24 November 1964. Although this would have provided a larger station than Skylab while also using a single Saturn V launch, the idea was not pursued further.

Use of the Apollo LM as an earth-orbiting laboratory was proposed for Apollo Applications Programme missions. The LM would have its engines and propellants removed, providing space for up to 10 tonnes of scientific equipment. A specific version of the LM lab was the Apollo Telescope Mount.

A McDonnell concept for using Gemini for extended duration missions. The basic Gemini would dock with an Agena upper stage. Between the docking collar and the Agena is an orbital shelter where the crew would live and work for weeks at a time. The crew would transfer from the Gemini to the miniature space station via an inflatable airlock.

The Orbital Workshop (OWS) was a 1960�s NASA program to create an embryonic space station in orbit using the spent S-IVB rocket stage of a Saturn IB. Once in orbit, the station would be visited by a crew launched by a Saturn IB in an Apollo CSM. The crew would dock with the station, vent the residual propellants from the S-IVB stage, fill the hydrogen tank with a breathable oxygen atmosphere, and then enter the tank and outfit it as a station.

The Apollo Telescope Mount began as a solar telescope built into the spaceframe of an Apollo lunar module. Initially it was to be either fre-flying (operated by a visitng crew in an Apollo CSM) or launched separately and docked to a Saturn S-IVB orbital workshop. Over many years it evolved into a piece of hardware unrelated to the Apollo LM and integrated into the Skylab space station.

Under the Apollo Applications Programme NASA began hardware and software procurement, development, and testing for a lunar mapping and survey system. The system would be mounted in an Apollo CSM. The crew would operate the sytem during a one month mission to map the lunar surface. Emphasis would be on identifying the most scientifically interesting areas on the lunar surface for the lunar base phase of AAP. It was planned for the system to be tested in earth orbit in a single launch mission unrelated to the Orbital Workshop. The mission would have the primary objective of conducting manned experiments in space sciences and advanced technology and engineering, including the Earth-orbital simulation of LM&SS lunar operations. The LM&SS would be jettisoned after completing its Earth-orbital test. Planned launch date for the earth orbit mission was 15 September 1968.

Proposed version of Gemini for low-earth orbit solar or stellar astronomy. This would be launched by a Saturn S-IB. It has an enlarged reentry module which seems to be an ancestor of the 'Big Gemini' of 1967.

In 1967 it was planned that Saturn IB-launched Orbital Workshops would be supplied by Apollo CSM spacecraft and Resupply Modules (RM) with up to three tonnes of supplies and instruments. Following launch by a Saturn IB, the Apollo would back away, transpose, and dock with the RM, just as with the Lunar Module for the lunar missions. These modules could be left docked to the Workshop docking module. Later the Orbital Workshop became Skylab, launched by a Saturn V, and the RM's were not needed. However a descendent of the RM flew in the form of the Apollo-Soyuz Test Project Docking Module.

Concept for use of a Saturn V-launched Apollo CSM with an enormous 10 m diameter space laboratory equipped with a 3 m diameter astronomical telescope.

This was one of 18 conceptual designs published 25 April 1968 for the Earth-orbital spacecraft lunar module adapter laboratory prepared by spacecraft design experts of the MSC Advanced Spacecraft Technology Division. The configuration was developed to illustrate the extent to which the building block philosophy could be carried. It would utilize both Gemini and Apollo spacecraft and would require 2 unmanned launches and 10 manned logistic launches. The report was published 25 April 1968.

NASA�s baseline Space Station of 1970, which was to be operational at early as 1977, was a large earth orbiting laboratory having a crew of 12 and a minimum operational lifetime of 10 years with resupply flights every 90 days. The station would be launched, unmanned, by an Saturn INT-21 (modified two-stage Saturn V). The station would be activated after completion of initial rendezvous and docking operations by the space shuttle.

Follow-on to Skylab proosed by Douglas. The station would still use the S-IVB stage as the basis, but would be much more extensively outfitted for larger crews.

The external solar/meteoroid shield ripped off during ascent, tearing away one solar panel wing and debris jamming the remaining panel. Without the shield internal temperatures soared to 52 deg C (126 deg F). Launch of the first crew was delayed for 10 days to develop procedures and crew training to make the workshop habitable. Repairs by subsequent crews led to virtually all mission objectives being met. It was intended that the station would be revisited and boosted to a higher orbit on the third flight of the space shuttle. But delays in the shuttle program and higher-than-anticipated atmospheric drag led to the station decaying from orbit well before the first shuttle launch. Skylab re-entered the earth's atmosphere amid worldwide hysteria on July 11, 1979, with chunks of the disintegrating space station crashing over a wide area of Australia.Payload: Imaging cameras. White-light coronagraph. Ultraviolet scanning polychromator- spectroheliometer. Extreme ultraviolet and X-ray telescope. Space manufacturing experiments. Externally mounted Earth resources instruments included a multispectral imaging camera, an Earth terrain camera, an infrared spectrometer, a multispectral scanner, a microwave radiometer/scatterometer and altimeter, and an L-band microwave radiometer. From fore to aft, Skylab was made up of the following modules, each with their own development history and heritage from the earlier Orbital Workshop and Apollo Applications Program: MDA Multiple Docking Adapter: 5.2 m x 3.05 ft diameter / ATM Apollo Telescope Mount: 3.96 m x 3.05 ft diameter / AM Airlock Module: 5.49 m x 3.05 ft diameter / IU Instrument Unit: 0.9 m x 2.04 m diameter / OWS Orbital Workshop: 14.6 m x 6.7 ft diameter.

Growth of Space Station into a 50 man Space Base was a required capability in the Phase B NASA Space Station studies of 1969-1970. The original core Station Module was to be used in the Base build-up several years later or was to be used as a prototype of one of the Space Base modules. Space Base would serve as a major international facility for research, applications and for the support of other space operations such as servicing unmanned satellites. The crew would be large enough to include specialists of many kinds and to minimise even more the need for astronaut-type training. The Space Base would provide nearly equal zero and artificial gravity volumes and would be configured with permanent dedicated laboratories and observatories in addition to general purpose facilities.

NASA had the long range goal of sending men to explore the planet Mars. To assure that the developments undertaken as part of the Space Station program contributed to this long term goal without undue increase in program cost or complexity, an assessment was made to determine where common or near common requirements existed. Two manned Mars missions, a 1981 opposition class mission and a 1986 conjunction class mission, were selected as representative types about which to develop total vehicle and operational concepts. These concepts involved the use of two Nuclear Shuttles for Earth departure and a third Shuttle to accompany the planetary spacecraft for use in braking into Mars orbit, in Mars orbit departure and in braking into a highly elliptic Earth orbit.

In view of the suspension of Saturn V production, alternative launch approaches and station configurations were investigated by NASA and its contractors in the 1970-1972 period. These included the combination of an expendable upper stage like the Saturn S-II or S-IVB mounted on the then-planned Shuttle recoverable booster to retain the potential to orbit monolithic core space stations. After the shuttle go-ahead Congress and President Nixon's Office of Management and Budget indicated they were prepared to pay for only one project at a time. Studies then moved to station concepts where the core was modularised so that it could be carried inside the Shuttle orbiter payload bay. These 4.5-meter diameter modules would then be assembled into a cluster in orbit with the same functional capability as the monolithic station concepts. In these configurations, it proved advantageous to use floors arranged parallel rather than perpendicular to the cylinder axis. The North American Rockwell and McDonnell-Douglas space station study contracts were extended until January 1972 to cover modular space station work. NASA was still hoping to launch a smaller space station in 1978, but the budget crunch soon forced the agency postpone its space station plans to the 1980s. When all Saturn V production capability was irrevocably lost in the early 1970�s, these studies formed the basis of what would later be the International Space Station.

NASA carried out a number of space station studies while the Shuttle was being developed in the mid-1970s. The first was McDonnell-Douglas' Manned Orbiting Facility (MOF) , a small 4-man space station that would have been configured differently for various missions, much like the Soviet Salyut stations.

Another 1970s design was North American Rockwell's 'Austere Modular Space Station'. The most important application in those days was constructing large space structures, e.g. extremely large communications satellites , giant 20 kilometre-wide solar power satellites or even giant orbiting space colonies for millions of people. Contemporary space station studies such as Rockwell's and Boeing's were closely tied to this objective. NASA's Outlook for Space report from 1975 recommended a number of possible goals, including development of a 12-man space station in low Earth orbit by 1988 and a similar station in lunar orbit by 1994.

The ASTP docking module was basically an airlock with docking facilities on each end to allow crew transfer between the Apollo and Soyuz spacecraft. The docking module was 3.15 m long, 1.4 m maximum diameter, and weighed 2,012 kg. Apollo's cabin atmosphere was 100 percent oxygen at 0.34 atmosphere pressure, while that of Soyuz was nitrogen/oxygen at 1.0 atmosphere. Transfer between these two atmospheres would require pre-breathing of pure oxygen to purge the blood of suspended nitrogen. This was avoided by lowering the Soyuz pressure to 0.68 atmospheres pressure. The docking module served mainly as an airlock to raise or lower the pressure between 0.34 and 0.68 atmospheres when moving from one spacecraft to the other. This was done through the use of pressure equalisation valves with both hatches closed.

The Space Operations Center was proposed by NASA's Johnson Spaceflight Center in 1979. Like most other space station studies from the mid/late 1970s its primary mission was the assembly and servicing of large spacecraft in Earth orbit -- not science. NASA/JSC signed a contract with Boeing in 1980 to further develop the design. Like most NASA space station plans, SOC would be assembled in orbit from modules launched on the Space Shuttle. The crew's tour of duty would have been 90 days. NASA originally estimated the total cost to be $2.7 billion, but the estimated cost had increased to $4.7 billion by 1981. SOC would have been operational by 1990.

While NASA/Johnson was studying the Space Operations Center concept, the Marshall Space Flight Center was lobbying for its own station -- the Science and Applications Manned Space Platform (SAMSP). MSFC envisioned a series of cheap 'platforms' costing only $500 million that could be outfitted for different missions. One mission would be to service spacecraft such as the Hubble Space Telescope. The platform would provide power, communications, thermal control and other services for standard Shuttle payload experiments -- it essentially served as a surrogate Shuttle payload bay. SAMSP could gradually evolve into a manned space station by adding pressurised crew modules derived from Spacelab. Initially, SAMSP would have a crew of three to four astronauts.

NASA studied several concepts in the 1980's using the 'wet workshop' approach to the capacious External Tank carried into orbit with every shuttle flight. Despite the incredible logic of this, NASA management never pursued it seriously - seeing it as an irresistable low-cost alternative to their own large modular space station plans.

In 1982 Space Industries Inc. planned to develop an 'Industrial Space Facility'(ISF):a 'mini space station' that would fly unmanned most of the time but be serviced regularly by the Space Shuttle. ISF would have housed up to 11,000kg (71 m3) of commercial microgravity and industrial manufacturing experiments in 31 payload racks; twin 140 m2 solar panels would have produced 20 kW of power. But endless political wrangling and NASA policy changes after the Challenger disaster delayed to the next millenium.any industrial exploitation of space.

NASA regarded a permanently manned space station as the next 'logical step' in manned spaceflight after the Space Shuttle entered service in April 1981. The agency formed a Space Station Task Force in May 1982 to study possible user requirements. In August 1992, NASA awarded eight $1-million study contracts to Boeing, McDonnell-Douglas, TRW, Rockwell, Grumman, General Dynamics/Convair and Martin Marietta. The contractors reported back in March 1983.....

The Spacelab was designed by the European Space Agency to fit in the US space shuttle payload bay and allow extended experiments to be conducted in orbit. Spacelab and the Canadian remote manipulator arm were the remnants of NASA's efforts to internationalise the shuttle program at its inception. In the absence of the planned space station, Spacelab provided the only opportunity for America to carry out extensive man-tended experiments in space from Skylab in 1973 until the Shuttle-Mir programme of 1995. Spacelab's modules could be varied to meet specific mission requirements. Its four principal components were the pressurised module, which contained a laboratory with a shirt-sleeve working environment; one or more open pallets that exposed materials and equipment to space; a tunnel to gain access to the module from the shuttle cabin; and an instrument pointing subsystem. Spacelab was not deployed free of the orbiter, although ESA did consider free-flying configurations at various times over the years.

The Orbital Manoeuvring Vehicle (OMV) was an important component in NASA's future Space Station plans in the 1980s. As a separately funded part of the 1984 Space Station plan, the OMV was intended as a short range robotic 'space tug' that could move payloads about in the vicinity of the Shuttle and Space Station.

In order to increase the Space Station's and Space Shuttle's appeal, NASA tried to involve as many users as possible. Hence the 1984 Space Station program would also include a large unmanned platform for Earth observation. NASA claimed this Polar Platform would utilise many of the same systems as the Station and be serviced by the Space Shuttle, although it would reside in a different (polar-) orbit than the main Station complex. The Polar Platform was finally transferred to the 'Mission to Planet Earth' remote sensing program in late 1990 when the Space Station's budget again was reduced.

The NASA Concept Definition Team eventually selected the Boeing/Grumman 'Power Tower' design as its baseline. It would provide maximised user viewing opportunities, a clear area for Shuttle dockings and versatility in Station growth. The design was also less sensitive to changes in mass caused by the addition of modules to the Station. The 'Power Tower' station's main structure was to be 122 meters tall with 75 kW solar panels sticking 41 meters to either side of the centreline. There were nine articulated attachments for external payloads dedicated to Earth and space observation. The initial Station would have had a crew of six working on 12-hour shifts, and feature two US-developed laboratory modules plus two habitation modules.

Despite strong opposition from other Reagan Administration officials (most notably science advisor George Keyworth and Secretary of Defense Caspar Weinberger), the President finally approved the space station project in January 1984. Two years of determined NASA lobbying had finally paid off. Scientists and the military were opposed to the project, however, so NASA promised Reagan that the first two years of the project would be devoted to low-cost definition studies. NASA had agreed to develop a facility that would meet certain requirements while costing no more than $8 billion at 1984 rates. The main justifications for the Space Station project were 'jobs and foreign policy prestige.' In his January 1984 speech, the President directed NASA to invite 'America's friends and allies' so that 'we can strengthen peace, build prosperity, and expand freedom for all who share our goals.' Reagan showed the Space Station model to the other G7 leaders at the London economic summit in June 1984.

NASA radically changed its Space Station baseline design in October 1985 following frequent complaints from users and astronauts. The new 'Dual Keel' Station was largely based on Lockheed and McDonnell-Douglas designs and its structure was much stiffer and hence easier to stabilise. It would offer additional space for external instruments plus a better microgravity environment than the previous gravity gradient-stabilised 'Power Tower.' The number of crew members was increased to 8 astronauts because scientists were concerned that a crew of six would be too busy with assembly and maintenance tasks and have no time for research. NASA's target date for the launch of the first element was now January 1993 while the initial operational capability had slipped to January 1994 mainly because the Fiscal 1986 budget was reduced from $280 million to just $200 million.

The Automated Transfer Vehicle was first proposed in the mid-1980s as a way to transport unmanned cargo to the Space Station. The Ariane-5 would launch the ATV. Early studies focused on a modified version of the Ariane-5's L9.7 upper stage -- the 'ARIES' concept -- but by 1992 the European Space Agency had decided a custom-built propulsion module would be more efficient. A pressurised or unpressurised Cargo Carrier module would transport up to 9000 kg of supplies.

The 1987 Space Station redesign greatly increased the importance of the Canadian contribution to the international project. Canada joined the project in March 1985 and initially proposed an 'Integrated Servicing and Test Facility' that would have consisted of two robotic arms plus satellite repair facilities. When the Space Station plan was changed in 1987, its satellite servicing element was postponed indefinitely. The Canadian robotic arm was now necessary for assembling the Station itself, since the Shuttle's existing 'Canadarm' manipulator only could handle 29.5t loads. The redesigned 'Canadian Mobile Servicing Center' would be used to dock the Shuttle and, possibly, payloads launched on expendable launchers to the Station.

One of the Science and Applications Manned Space Platform's most important missions was to serve as a 'space harbour' for missions to geostationary orbit, where most communications satellites are located. Large satellites would be delivered to SAMSP from Earth by the Space Shuttle for final assembly and checkout. An Orbital Transfer Vehicle or space tug would then transport the satellite to geostationary orbit. The space tug would be permanently based at the space station in low Earth orbit. NASA/Johnson also regarded the space tug as an integral component of its Space Operations Center plan.

Britain initially expressed strong interest in developing an unmanned Polar Platform for Earth observation as part of the European Columbus package. In 1986 the platform was scheduled for a 1995 launch. By 1987 the launch date had slipped by two years as the British were expressing doubts about the Space Station project. Britain finally pulled out in February 1988 and the design was scaled back to a smaller satellite based on the French SPOT-4 spacecraft bus. The design was retained when the British decided to rejoin a year later, but British Aerospace was appointed main contractor of the project. The $972-million POEM-1 project was moved out of the Columbus space station package in November 1991 and was subsequently descoped into Envisat-1.

The early Space Station proposals assumed the facility would be equipped with a 'safe haven' where the crew would wait for a rescue Shuttle in case of emergency. After the 1986 Space Shuttle Challenger accident, it became obvious that some sort of 'lifeboat' would have to be added....

The Japanese Experiment Module (JEM) has been a rare island of stability in the often tumultuous Space Station program. Conceived in 1985, JEM consists of a pressurised laboratory mainly dedicated to advanced technology experiments, a logistics module, an unpressurised pallet for vacuum experiments in space plus a small robotic arm. The Japanese National Space Development Agency (NASDA) formally submitted the JEM proposal to NASA in March 1986. The Japanese Space Activities Commission recommended formal participation in the Space Station project five months later and the JEM design changed little since the mid-1980s.

After the 1986 Space Shuttle Challenger accident, a number of space policy reports ('Pioneering the Space Frontier', 'Leadership and America's Future in Space') advocated an aggressive manned lunar/Mars program to restore America's lead in space. NASA now embarked on a number of studies to see how the downscaled Space Station Freedom could assist this goal. This would involve use of a large spacedock facility for assembly and checkout of manned lunar or planetary spacecraft.

NASA decided to develop a $288-million Flight Telerobotic Servicer in 1987 after Congress voiced concern about American competitiveness in the field of robotics. The FTS would also help astronauts assemble the Space Station, which was growing bigger and more complex with each redesign. Martin Marietta and Grumman received $1.5-million study contracts in November 1987. Martin Marietta received a $297-million contract in May 1989 to develop a vehicle by 1993. The Bush Administration briefly tried to commercialise the FTS project in early 1989. The contractors objected since the FTS had no commercial customers. The FTS was then combined with the Orbital Manoeuvring Vehicle into the Robotic Satellite Servicer concept.

The Space Station's free-flying unmanned platforms were all deleted in 1987-90 to compensate for the budget cuts. However, some of them may yet be reintroduced in the 21st century. One possibility was a space telescope capable of detecting planets orbiting around nearby stars. It would be serviced by International Space Station astronauts. The early 1984 Space Station plan briefly featured a similar 'Astro' platform.

The H-2 Transfer Vehicle. The September 1988 Space Station Intergovernmental Agreement allowed ESA and NASDA to use the Ariane-5, H-2A or other indigenous launchers for resupplying their Station modules. NASA promised to provide all the necessary rendezvous and docking information to designers in Europe and Japan. Each partner will pay the full cost of maintaining its own hardware elements on the Station and they will also have to reimburse NASA for using Space Shuttle and Tracking and Data Relay Satellite services. The Japanese HTV can transport about 7t of pressurised, unmanned cargo to the Space Station. Unlike ESA's Automated Transfer Vehicle and Russia's Progress, the HTV can carry International Standard Payload Racks but it has no docking capability. Instead, the HTV will rendezvous with the Canadian robotic arm which moves it to one of the Space Station's docking hatches.

NASA's first detailed cost assessment for the US space station caused a political uproar in Congress, where many politicians had started to express doubt about the project. However, NASA and Reagan Administration officials reached a compromise in March 1987 which allowed the agency to proceed with a cheaper $12.2-billion Phase One Station. This design initially omitted the $3.4-billion 'Dual Keel' structure and half of the power generators. The new Space Station configuration was named 'Freedom' by Reagan in June 1988.

As Herm�s gradually faded into oblivion, the European Space Agency started to take a closer a look at cheaper and less complicated manned space capsules. An 'Ariane-X' crew rescue capsule was part of the preliminary European space station studies in the late 1980s, and the French and Italian aerospace industry also investigated unmanned concepts such as the 'Carina' version in 1990. 'Carina' was to have a diameter of 4 meters and would be launched on the Ariane-4 rocket. Its main mission was commercial microgravity experiments. The European Space Agency started a six-month Phase 1 'Assured Crew Return Vehicle' study in October 1992. Aerospatiale, Alenia Spazio and Deutsche Aerospace were prime contractors. In June 1993, the European Space Agency announced that a simpler manned space capsule would replace the Herm�s manned spaceplane project.

The Orbital Manoeuvring Vehicle also encountered many problems in 1989-90 as the estimated total cost ballooned to $1 billion dollars -- an increase of $600 million. NASA then tried to integrate the OMV and Flight Telerobotic Servicer into a 'Robotic Satellite Servicer.' TRW and Martin Marietta were awarded $1.3-million phase B contracts in June 1990. However, neither project survived the Space Station redesign in late 1990; the cost was too high. The FTS was no longer necessary after the Space Station in-orbit assembly procedures were greatly simplified in 1990-91 while the OMV became less important after the Station's free-flying space platforms were cancelled.

Following the collapse of the Space Station Freedom project, NASA unveiled its new Space Station design in March 1991. The resulting configuration was mockingly referred to as 'Fred' by the programs critics, underscoring the truncated nature of the design. The Space Station assembly sequence was greatly simplified by switching to shorter, prefabricated truss segments that required no assembly in space. Only 250-300 hours of annual EVA 'spacewalks' were now required for maintaining the Station's external areas. One set of solar arrays were deleted, reducing the power from 75 kW to 56 kW although 30 kW still would be available for users.

As NASA's Space Station budget received further cutbacks, the agency was forced to consider more and more hardware paid for by foreign space agencies although Congress and private industry were opposed to it. In 1992, Italy's Alenia Spazio announced they would build a small Mini-Pressurised Logistics Module (MPLM) for the Space Shuttle, enabling it to carry 4500kg of cargo to the Space Station. The MPLM might also be transformed into a small life sciences laboratory. Boeing had previously wanted to build the MPLM, but NASA could not afford to pay for it. Instead, the Italian space agency, ASI, would now finance the $400-million project in return for crew time and experiments on the Space Station.

In October 1993, ESA decided to further slash its overall budget by a combined $4.8 billion in 1994-2000. The Columbus space station module survived, but in a reduced form. It would now cost $900 million less than the proposed $3.1 billion through 2000. The new Columbus Orbiting Facility (COF) was shorter and lighter. It was based on the same Alenia-developed pressurised module as the Multi-Purpose Logistics Module.

When the International Space Station (ISS) was redesigned again in 1993, it was decided to expand the original Mini-Pressurised Logistics Module design. The new Multi-Purpose Logistics Module was twice as long and could carry 9000kg of cargo to ISS. The European Space Agency also became a partner, since Alenia Spazio would use the same pressurised module and some thermal subsystems in the Columbus Orbiting Facility as well. In return, ESA provided three environmental control and life-support system units for use in the Multipurpose Logistics Module. The module carried sixteen International Standard Payload Racks.

Following the collapse of Space Station Fred, NASA quickly formed a Space Station redesign team which identified three major redesign options in April 1993....

Founded by Bob Citron in 1982, Spacehab Inc. was the only entrepreneurial company to successfully develop a commercial manned spaceflight module. Spacehab was initially formed to develop a 5000 kg pressurised module derived from ESA's Spacelab. The 3 meter long Spacehab module was carried inside the Shuttle cargo bay and provides 28.3 cubic meters of expanded habitable space for experiments and logistics transport to space stations.

Further Russian cutbacks lead to the Russian Science and Power Platform being replaced with one of the four American solar arrays. The RSPP was originally going to be launched on six Russian Proton rockets fairly early during the assembly phase, but the platform, now postponed, will be launched on an American Shuttle if it is ever ready. The Science and Power Platform would only power the Russian laboratory modules, however, so unlike the Service Module it is not crucial to the success of the whole ISS project.

At the same time, NASA had scaled down its space station in the seventh redesign in nine years. This more modest station Alpha deleted most of the original science experiments, but would still cost more than Clinton was willing to spend. In October 1993, with the gunfire of the coup attempt outside their windows, NASA negotiators in Moscow agreed to the 'International Space Station' (ISS), a merger of stations Alpha and Mir-2.

The Russian Zarya FGB space tug was the cornerstone of the new International Space Station since it acted as an adapter between the US and Russian-built ISS segments and also provided some propulsion and propellant storage capabilities. It was closely based on the older Russian TKS spacecraft design that was intended as a ferry for the Almaz military station. The United States paid $220 million for the FGB (vs. $450 million for Lockheed's rejected 'Bus-1' option) and Khrunichev successfully completed the project on schedule and within budget. However, the launch had to be delayed by 17 months to November 1998 because the Russians were unable to complete their own ISS Zvezda service module on time.

Cost overruns soon forced NASA to consider other options for the International Space Station's habitation module. The space agency originally intended to use the same 8.2-meter long habitation module as the final 1991 Space Station Freedom design. In late 1998, NASA's Johnson Space Center proposed a much larger and lighter inflatable 8-meter diameter 'Transhab' module that also could be converted into crew quarters for future manned missions to the Moon and Mars. It was also possible that the module could be built and paid for by private industry and leased to NASA, although the exact configuration wasn't clear. Transhab and the 8.2-meter module appeared to be equally expensive ($100 million in 1998) and NASA had not made a final decision.

The Russian economic crisis provided some intriguing opportunities for private industry. Spacehab Inc. and NPO Energia announced a small commercially financed laboratory that would be launched on a Zenit rocket in 2003. The 'Enterprise' module would contain a windowed 'studio bay' giving crew members views of the Station, arriving vehicles and Earth. Loosely based on the Progress cargo spacecraft, the 'Enterprise' interior was to be divided into two sections - a 64 position equipment bay able to accommodate standardised Station Express racks, Shuttle mid-deck lockers and Spacehab module lockers - and the studio bay.

The Zvezda service module of the International Space Station had its origins a quarter century before it was launched. The Mir-2 space station was originally authorised in the February 1976 resolution setting forth plans for development of third generation Soviet space systems. It would undergo many changes over the year, with only one thing remaining constant: the starting point was always the DOS-8 base block space station core module, built as a back-up to the DOS-7 base block used in the Mir station. When the International Space Station was agreed to, the $3-billion DOS-8 became the first Russian segment of the station, originally known as the Service Module. The original plan called for a first launch in June 1997 of the ISS Zarya tug followed by the Russian Service Module in September. ISS would then be permanently manned from January 1998 onwards. This launch schedule was delayed by more than two years due to Russia's economic problems.