Apollo 1

Last year we looked at the Challenger. This year: Apollo 1. On January 27, 1967, the three-man crew of Gus Grissom, Roger Chaffee, and Ed White who were in training for the first Apollo flight were asphixiated in their capsule during a training exercise. The men reported communications glitches prior to the disaster, and it is believed that a spark in their pure-oxygen atmosphere quickly started an unstoppable blaze, consuming the many flammable components in the capsule. There were three hatches between the men and the outside of the capsule, which were not designed to be opened in less than 90 seconds. In addition, it is doubtful that the astronauts could have opened the internal hatch at all since pressure inside the spacecraft rose rapidly after the fire, exceeding the capacity of the pressure-equalization valves. Future designs were modified to remove most of the flammable components from the crew area and include a new quick-opening hatch. NASA has a retrospective.