The Soviets won the race to place the first space station in orbit. On April 19, 1971, they launched Salyut 1.
The Skylab and Salyut missions firmly established the feasibility of extended stays in orbit and of performing fundamental—if rudimentary—research. In order to move beyond their limitations, a quantum leap forward in technology, something truly revolutionary, would be required.
Space stations, especially the most recent ISS, were designed to keep the astronauts as comfortable as possible—the ISS modules are roomy, bright, and kept at a constant 70 degrees Fahrenheit. It is important that the crew members are comfortable because they are kept busy all their waking hours.
Prior to the first flights of Salyut and Skylab, the effects of long-term exposure to a weightless environment were a matter of speculation. Aerospace engineers and space medicine teams from both the Soviet Union and the United States understood that unless humans could adequately adapt to weightlessness, hopes for more sophisticated space stations and long-duration spaceflights would never be realized.
On each mission, when not subjecting themselves to medical and psychological testing, space station crews perform hundreds of scientific experiments. All experiments are selected by a panel of NASA scientists from thousands of suggestions.