The stocky, crew-cut Grissom, an Air Force major,* was an old-timer in NASA's manned space flight program, one of the original seven Mercury astronauts picked five years earlier. He already had a quarter of an hour of spacecraft flying time as passenger on the suborbital flight of Liberty Bell 7 in July 1961, Project Mercury's second manned mission, and would therefore be the world's first two-time space flyer. Young, his crewmate, was a younger man and a newer astronaut; a Navy lieutenant commander, he had been one of the nine pilots selected for the space program in September 1962. Schirra, like Grissom, was one of the Mercury seven. Born in 1923, he became the old man of the astronauts corps when John Glenn resigned early in 1964. In October 1962, Schirra had ridden Sigma 7 (the fifth manned Mercury spacecraft) through six orbits in the penultimate Mercury mission.  Stafford, Schirra's co-pilot in the backup crew, was an Air Force major who became an astronaut at the same time as Young.** 2
Gilruth voiced NASA's "high hopes of flying by the end of the year," 1964,3 leading America back into space after an 18-month hiatus. Those hopes foundered in the storms that lashed Cape Kennedy during the summer. When the launch vehicle for Gemini 2, after passing so smoothly through test and checkout, betrayed the mission in December, even Gemini's unmanned prelude remained unfinished at year's end. But the opening quarter of 1963 saw the success of Gemini 2 in January and then, scarcely two months later, Grissom and Young in orbit aboard "Molly Brown." With that, Project Gemini had clearly advanced a long step beyond Mercury and opened a new era in manned space flight.
* Grissom, a captain in the Air Force when he joined the astronaut ranks, had been promoted to major in July 1962, one year after his Mercury flight.
** The others who became astronauts with Stafford and Young were Neil A. Armstrong, Frank Borman, Charles Conrad, Jr., James A. Lovell, Jr., James A. McDivitt, Elliot M. See, Jr., and Edward H. White II. They were introduced to the public on 17 September 1962.
1 "News Conference, GT-3 Crew Selection," 13 April 1964, pp. 1, 2, 5.
2 U.S. Congress, House, Committee on Science and Astronautics, Astronautical and Aeronautical Events of 1962: Report, 88th Cong., 1st sess., 12 June 1963, p. 122; William Hines, "Life-sized Grissom Rides Again," The Evening Star, Washington, 30 March 1965; U.S. Congress, Senate, Committee on Aeronautical and Space Sciences, United States Astronauts: Staff Report, Senate Doc. No. 42, 88th Cong., 1st sess., 15 Nov. 1963, pp. 7, 11, 31, 35; Astronautics and Aeronautics, 1964: Chronology on Science, Technology, and Policy, NASA SP-4005 (Washington, 1965), pp. 15-16; NASA Release No.65- 81, "Project: Gemini-Titan 3," press kit, 11 March 1965, pp. 4349; NASA News Release 62-200-A, "Nine New Pilots Selected for Space Flight Training," 17 Sept. 1962.
3 "GT-3 Crew Selection," p. 5.