NASA Astronaut Group 4 was a group of six astronauts selected by NASA in June 1965. While the astronauts of the first two groups were required to have an undergraduate degree or the professional equivalent in engineering or the sciences, they were chosen for their experience as test pilots. Test pilot experience was waived as a requirement for the third group, and military jet fighter aircraft experience could be substituted. Group 4 was the first chosen on the basis of research and academic experience, with NASA providing pilot training as necessary. Initial screening of applicants was conducted by the National Academy of Sciences.

Skylab was the United States' first space station, launched by NASA, occupied for about 24 weeks between May 1973 and February 1974. It was operated by three trios of astronaut crews: Skylab 2, Skylab 3, and Skylab 4. Operations included an orbital workshop, a solar observatory, Earth observation and hundreds of experiments. Skylab's orbit eventually decayed and it disintegrated in the atmosphere on July 11, 1979, scattering debris across the Indian Ocean and Western Australia.