On July 28, 1962 a bug in the flight software for the Mariner I space probe caused the rocket to divert from its intended path on launch. Mission control destroyed the rocket over the Atlantic Ocean.
"The investigation into the accident discovered that a formula written on paper in pencil was improperly transcribed into computer code, causing the computer to miscalculate the rocket's trajectory."
In 2005 Wired Magazine characterized this bug as the first of the "ten greatest software bugs of all time."