Mariner 1

Mariner 1 was the first spacecraft of the American Mariner program. Launched on July 22, 1962 as a Venus flyby mission, a range safety officer ordered its destructive abort at 09:26:16 UT, 294.5 seconds after launch. According to NASA's current account for the public:

The booster had performed satisfactorily until an unscheduled yaw-lift (northeast) maneuver was detected by the range safety officer. Faulty application of the guidance commands made steering impossible and were directing the spacecraft towards a crash, possibly in the North Atlantic shipping lanes or in an inhabited area. The destruct command was sent 6 seconds before separation, after which the launch vehicle could not have been destroyed. The radio transponder continued to transmit signals for 64 seconds after the destruct command had been sent.

What NASA's website describes as "improper operation of the Atlas airborne beacon equipment" caused the booster to lose contact with one of the guidance systems on the ground, setting the stage for an apparent software-related guidance system failure. The role of software error in the launch failure remains somewhat mysterious in nature, shrouded in the ambiguities and conflicts among (and in some accounts, even within) the various accounts, official and otherwise. It was launched by an Atlas-Agena rocket.

The probe's mission was later completed by Mariner 2. However, the cryptic nature of the problems that led to the decision to abort Mariner 1, as well as the confusion in various reports on the incident, gave rise to an urban legend of sorts. Indirectly, this confusion also contributed to some software engineering folklore about the role of supposed Fortran code in the guidance systems. This folklore has persisted at least as late as 2006, despite a lack of evidence that Fortran was even in use for real-time guidance computations for the Mariner missions.