Jack Swigert on the Apollo 13 Spacecraft

Jack Swigert and his two crewmates are in a cramped cone perched atop a massive Saturn V rocket. They're lying face up, their backs resting on what NASA calls couches, but they're really just metal frames covered in cloth. In the weightlessness of space, the seats don't need padding, but down here on Earth, after an hour, the frame is digging into Swigerts back. Some critical buttons on the instrument panel have plastic wickets over them so no one can accidentally press them. It takes another two hours for the astronauts and the ground crew to complete their preparations then at last, the countdown begins.