NASA Astronaut Group 4

Astronaut Group 4 (The Scientists) was the fourth group of 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 (with several holding advanced degrees), they were chosen for their experience as test pilots. Test pilot experience was waived as a requirement for the third group, but military jet fighter aircraft experience could be substituted. Group 4 was the first chosen on the basis of research and academic experience (an M.D. or Ph.D. in the natural sciences or engineering was a prerequisite for selection), with NASA providing pilot training as necessary. Initial screening of applicants was conducted by the National Academy of Sciences, which characterized the pool as "disappointing."

Of the six ultimately chosen, four had military experience, with Garriott having previously completed the USAF Pilot Training Program. Schmitt, a geologist, walked on the Moon, while Garriott, Gibson and Kerwin all flew to Skylab. Garriott also flew on the Space Shuttle. Graveline and Michel left NASA without flying in space.

...
Wikipedia