THE deaths of the astronauts brought to a head longstanding differences between advocates of pure-oxygen atmospheres for spacecraft and those who favor a two-gas system. The fire hazard inherent in a pure-oxygen system had discomforted space officials for years. In 1962, two crewmen in a space-cabin simulator at San Antonio were overcome by fumes from an instrument-panel fire but were rescued without serious injury. The same year, four men in an oxygen-filled test chamber in Philadelphia suffered second-degree burns when a short circuit in a lighting fixture caused a fire.
A 1964 NASA...