Space Station Freedom was a NASA project to construct a permanently manned Earth-orbiting space station in the 1980s. Although approved by then-president Ronald Reagan and announced in the 1984 State of the Union Address, Freedom was never constructed or completed as originally designed, and after several cutbacks, the project evolved into the International Space Station program.

In the early 1980s, with the Space Shuttle completed, NASA proposed the creation of a large, permanently manned space station, which then-NASA-Administrator James M. Beggs called "the next logical step" in space. In some ways it was meant to be the U.S. answer to the Soviet Mir. NASA plans called for the station, which was later dubbed Space Station Freedom, to function as an orbiting repair shop for satellites, an assembly point for spacecraft, an observation post for astronomers, a microgravity laboratory for scientists, and a microgravity factory for companies.

Reagan announced plans to build Space Station Freedom in 1984, stating: "We can follow our dreams to distant stars, living and working in space for peaceful economic and scientific gain."

The 1990 Space Exploration Initiative called for the construction of the Space Station Freedom. Following the presidential announcement, NASA began a set of studies to determine the potential uses for the space station, both in research and in industry, in the U.S. or overseas. This led to the creation of a database of thousands of possible missions and payloads; studies were also carried out with a view to supporting potential planetary missions, as well as those in low-earth orbit.

Several Space Shuttle missions in the 1980s and early 1990s included spacewalks to demonstrate and test space station construction techniques. After the establishment of the initial baseline design, the project evolved extensively, growing in scope and cost.

In April 1984, the newly established Space Station Program Office at Johnson Space Center produced a first reference configuration; this design would serve as a baseline for further planning. The chosen design was the "Power Tower", a long central keel with most mass located at either end. This arrangement would provide enough tidal forces to keep the station aligned with the keel pointed towards the Earth, reducing the need for thruster firings. Most designs featured a cluster of modules at the lower end and a set of articulated solar arrays at the upper end. It also contained a servicing bay. In April 1985, the program selected a set of contractors to carry out definition studies and preliminary design; various trade-offs were made in this process, balancing higher development costs against reduced long-term operating costs.

In March 1986, the System Requirements Review modified the configuration to the "Dual-Keel" design, which moved the modules to the central trussplacing them at the center of gravity, providing a better microgravity environment. However, the desire to maintain tidal alignment led to the use of increased truss structure, with two large "keels".

As the international involvement became more organized, the number of U.S. lab modules was reduced from two to one, taking into consideration the provision of space in the European and Japanese modules. Following this, the design was extensively "scrubbed" to remove inefficiencies; this led to a large number of subsystems being revised or removed, the deferral of plans for an Orbital Maneuvering Vehicle to be based at the station, and the use of only a single habitation module for a crew of eight.

In May 1986, NASA produced a report which had studied the assembly sequence with the intent of providing early "man-tended" capacity, ensuring that at an early stage, despite the station not being able to support a crew, research work could be carried out by occasional visiting Shuttle flights. Following the Challenger accident, a Critical Evaluation Task Force was set up to reassess the validity and safety of the Station design. While this validated the use of the Dual-Keel design, post-Challenger safety concerns led to changes in the assembly plans, as well as assorted minor changes. Johnson Space Center had previously expressed misgivings about the amount of EVA work needed to assemble the station, which were addressed, as were the Shuttle payload reductions stemming from safety improvements post Challenger.

In September 1986, a major cost review of the program was undertaken from the post-Challenger baseline; this review was intended to ensure that NASA had a solid basis for its commitment to cost and schedule. The review found that the total development cost for the Dual-Keel configuration would cost US$18.2 billion (in FY1989 dollars), and a slip in the first-element launch (FEL) date from January 1993 to January 1994.

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Space Station Freedom - Wikipedia, the free encyclopedia