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.
While flight-preparation crews were having problems, Grissom, White, and Chaffee were finding bottlenecks in training activities. The chief problem was keeping the Apollo mission simulator current with changes being made in spacecraft 012.
As Procedures Officer, Kranz was put in charge of integrating Mercury Control with the Launch Control Team at Cape Canaveral, Florida, writing the “Go/NoGo” procedures that allowed missions to continue as planned or be aborted, along with serving as a sort of switchboard operator using teletype between the control center at Cape Canaveral and the agency’s fourteen tracking stations and two tracking ships located across the globe.
At the beginning of the Apollo program, Kraft retired as a flight director to concentrate on management and mission planning. In 1972, he became director of the Manned Spacecraft Center, following the path of his mentor Robert Gilruth.