In 1962, a Mariner 1 probe bound for Venus was destroyed 293 seconds after launch because a single missing overbar in a line of guidance code told the rocket it was veering off course when it wasn’t, and Arthur C. Clarke later called it the most expensive hyphen in history.

On July 22, 1962, NASA's first planetary probe was destroyed 293 seconds after launch because a single overbar had been left off a line of guidance code. Arthur C. Clarke's verdict — 'the most expensive hyphen in history' — captured something new about the scale at which small mistakes had begun to matter. The post In 1962, a Mariner 1 probe bound for Venus was destroyed 293 seconds after launch because a single missing overbar in a line of guidance code told the rocket it was veering off course