On Jan. 27, 1967, the three Apollo 1 astronauts -- Gus Grissom, Ed White II and Roger Chaffee -- were preparing for what was to be the first manned Apollo flight. The astronauts were sitting atop the launch pad for a pre-launch test when a fire broke out in their Apollo capsule. The investigation into the fatal accident led to major design and engineering changes, making the Apollo spacecraft safer for the coming journeys to the moon.