NASA

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Astronaut Group 4 (“The Scientists”) was a group of six astronauts. They are pictured following MSC press conference announcing their selection by NASA in June 1965.
Front row, left to right, are Owen Garriott (physicist), Harrison Schmitt (astrogeologist), and Edward Gibson (physicist). Back row, left to right, are Frank Michel (physicist), Duane Graveline (physician), and Joseph Kerwin (physician).

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, and 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. Of the six ultimately chosen, four had military experience.
Schmitt was the only one to fly on Apollo and to walk on the Moon.

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A superb photograph illustrating the goal of Apollo to land a man on the Moon.

An Atlas Agena rocket lifts off from Cape Kennedy in the night sky. In the right background a floodlight is aimed at the Moon.

The Gemini missions featured rendezvous in space with unmanned Agena targets launched on Atlas space vehicles. These rendezvous in space were critical for the success of the Apollo Moon landings.