On 2014-09-15, Alan McKinnon <alan.mckin...@gmail.com> wrote: > My favourite Fortran story: > > One of the Mariner spacecraft yonks ago was sent a routine regular > course correction. It flew off at some wild angle and was never seen > again, and because the antenna was pointing in the wrong direction > comms could not be re-established. Oops. Expensive spacecraft down > the drain.... > > The bug was eventually trace to a comma instead of a period in some > Fortran code (made a huge difference). Note that many code reviews > missed the bug, and the compiler accepted it as valid syntax
While that is a good story, Wikipedia refers to it as "a legend", and NASA explicitly identifies a different cause. According to NASA failure was caused by faulty beacon equipment combined with an omitted hyphen in a data editing program. http://nssdc.gsfc.nasa.gov/nmc/spacecraftDisplay.do?id=MARIN1: The failure was apparently caused by a combination of two factors. Improper operation of the Atlas airborne beacon equipment resulted in a loss of the rate signal from the vehicle for a prolonged period. The airborne beacon used for obtaining rate data was inoperative for four periods ranging from 1.5 to 61 seconds in duration. Additionally, the Mariner 1 Post Flight Review Board determined that the omission of a hyphen in coded computer instructions in the data-editing program allowed transmission of incorrect guidance signals to the spacecraft. During the periods the airborne beacon was inoperative the omission of the hyphen in the data-editing program caused the computer to incorrectly accept the sweep frequency of the ground receiver as it sought the vehicle beacon signal and combined this data with the tracking data sent to the remaining guidance computation. This caused the computer to swing automatically into a series of unnecessary course corrections with erroneous steering commands which finally threw the spacecraft off course. -- Grant Edwards grant.b.edwards Yow! I want the presidency at so bad I can already taste gmail.com the hors d'oeuvres.
