Mercury-Redstone 4 was the fourth mission in the Mercury-Redstone series and the second U.S. manned suborbital spaceflight. The mission was essentially a repeat of Alan Shepard’s Freedom 7 flight. So why was it necessary to launch another sub-orbital mission? Why not proceed with an orbital flight to match the Soviet Vostok 1? Among other things the U.S. needed more space experience to corroborate the “Man-in-Space” concept. Also the Redstone was the only booster NASA had that was approved for manned launches. The Atlas booster was available but not ready. Atlas was capable of putting a Mercury Capsule into orbit, but it had been launched three times with unmanned capsules, and it had exploded on 2 of the 3 attempts.
“Some of those guys came in figuring, “I’ll write my textbooks and my thesis and teach [university courses] and I’ll come by twice a week and be an astronaut.” Well, that didn’t work …. We were devoting our lives to this whole thing, and you couldn’t devote anything less, I don’t care what your discipline was.”
With Group 4, for the first time, the selection criteria did not include a requirement for test pilot proficiency. Selectees who were not qualified pilots would be assigned to the Air Force for a year of flight training. The primary scientific requirement was a doctorate in medicine, engineering, or one of the natural sciences.
Selection of Group Two virtually depleted the pool of qualified candidates from the small corps of test pilots in the country, and it was the last group for which test-pilot certification would be a requirement. The new trainees reported to Houston in October 1962 to begin a two-year training course. A four-day work week was normally scheduled, the fifth day being reserved for public relations duties or for travel.