Apollo I
During a launch pad test of the Apollo I (AS-204) mission at Cape Kennedy on January 27, 1967, a flash fire suddenly broke out in the vehicle’s command module and killed its crew, Lt. Col. Edward White, II (U.S. Air Force), Lt. Col. Virgil ‘Gus’ Grissom (U.S. Air Force) and Lt. Cmdr. Roger Chaffee (U.S. Navy), pictured above. The fire consumed the command module mere seconds after the crew had reported it. Although the Apollo I test ended in tragedy, subsequent modifications to safety and planning contributed to the success of later Apollo missions–including the first landing on the moon and the first time a man walked on the moon.

Image: NASA