Nestled beside an umbilical tower, surrounded by a service structure, and encased in a clean room at Cape Kennedy's Launch Complex 34, spacecraft 012 sat atop a Saturn IB on Friday morning, 27 January 1967. Everything was ready for a launch simulation, a vital step in determining whether the spacecraft would be ready to fly the following month. During this "plugs out" test, all electrical, environmental, and ground checkout cables would be disconnected to verify that the spacecraft and launch vehicle could function on internal power alone after the umbilical lines dropped out.1
By 8:00 that morning, a thousand men, to support three spacesuited astronauts - Virgil Grissom, Edward White, and Roger Chaffee - were checking systems to make sure that everything was in order before pulling the plugs. In the blockhouse, the clean room, the service structure, the swing arm of the umbilical tower, and the Manned Spacecraft Operations Building, this army of technicians was to go through all the steps necessary to prove that this Block I command module was ready to sustain three men in earth-orbital flight. Twenty-five technicians were working on level A-8 of the service structure next to the command module and five more, mostly North American employees, were busy inside the clean room at the end of the swing arm. Squads of men gathered at other places on the service structure. If interruptions and delays stretched out the test, as often happened, round-the-clock shifts were ready to carry the exercise to a conclusion. Throughout the morning, however, most of the preparations went smoothly, with one group after another finishing checklists and reporting readiness.
After an early lunch, Grissom, White, and Chaffee suited up, rode to the pad (arriving an hour after noon), and slid into the spacecraft couches. Technicians sealed the pressure vessel inner hatch, secured the outer crew access hatch, and then locked the booster cover cap in place. All three astronauts were instrumented with biomedical sensors, tied together on the communications circuit, and attached to the environmental control system. Strapped down, as though waiting for launch, they began purging their space suits and the cabin atmosphere of all gases except oxygen - a standing operating procedure.2
1. Much of this chapter is based on Report of Apollo 204 Review Board to the Administrator, National Aeronautics and Space Administration (Washington, 1967), Floyd L. Thompson, chairman, 5 April 1967, with appendixes A through G (hereafter cited as RARB). Also basic are Senate Committee on Aeronautical and Space Sciences, Apollo Accident: Hearings, 8 parts, 90th Cong., 1st and 2nd sess., 7 Feb. 1967 to January 1968, and House Committee on Science and Astronautics, Subcommittee on NASA Oversight, Investigation into Apollo 204 Accident: Hearings, 3 vols., 90th Cong., 1st sess., 10 April to 10 May 1967. See also Senate Committee on Aeronautical and Space Sciences, Apollo 204 Accident: Report, 90th Cong., 2nd sess., 30 Jan. 1968, S. Rept. 956.
2. RARB, pp. 4-1 to 4-8, and append. D, pp. D-6-1 to D-6-86.