Ariane 5 explosion (1996)

After a decade of development, the European Space Agency launched the unmanned Ariane 5 rocket on June 4, 1996. Less than 40 seconds after takeoff, the rocket, carrying millions of dollars worth of scientific equipment, exploded over the swamps of French Guiana. The culprit: a coding error. The software was not protected from integer overflow, a computing mishap that occurs when a program attempts to stuff a 64-bit number into a 16-bit space.