Jan. 27, 1967 Test pilots can sense straightaway if they're working with a good vehicle or a bad one, and the Apollo 1 crew Gus Grissom, Ed White and the rookie Roger Chaffee knew almost immediately that they'd been assigned to a stinker. By late 1966, the last of the sturdy, two-man Gemini spacecraft had flown, and NASA was rolling out the three-man Apollo ships that would, at last, carry men to the moon. The spacecraft were sweet-looking machines, but in test-runs on the pad, they were a mess. The electrical system fritzed, the communications died, repairs and upgrades were late in coming. At the end of one practice session, a disgusted Grissom walked away from a simulator and left a lemon perched atop it. Most worrisome, however, was NASA's insistence on continuing to use 100% pure oxygen in its atmospheric systems an explosively flammable gas that had worked fine so far in the Mercury and Gemini ships but that could burn like gasoline in the presence of so much as an errant spark. Sticking with pure oxygen meant NASA was banking on its luck to hold. It didn't. Early one Friday evening, when the Apollo 1 astronauts were locked down in the spacecraft for a practice session out on the pad, just such a spark got loose from a frayed wire next to Grissom's seat. In less than a minute, all three men were dead. For a while, it seemed, the Apollo program would perish too.