Mariner 1

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Mariner 1 was the first spacecraft of the 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.[1] According to NASA's current account for the public:

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.

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.


An Infamous Bug

"The Most Expensive Hyphen in History"

The most consistent account was that the error was in hand-transcription of a mathematical symbol in the program specification, in particular a missing overbar. Yet the story persists of a "missing hyphen"    in the data or in the computer instructions, even somehow in the equations. No doubt several factors contributed to the "missing hyphen" narrative and its longevity, even in official accounts from technical cognoscenti at JPL and NASA. Among the factors cited (or obvious enough):

  • The overbar's resemblance to a hyphen.
  • The difficulty of explaining the real error to the American public and its elected representatives.
  • External political pressures and internal schedule pressures. After all, the mission was
    • an expensive failure of a three-way collaboration (JPL, NASA, USAF),
    • legitimized within the narrative of the US-USSR space race,
    • very high profile, as America's first planetary mission,
    • on a very tight schedule, as it was planned with a narrow launch window (45 days), leaving little time for inquiries, investigations or recriminations before the launch of Mariner 2. The official accounts (which included mentions of a missing hyphen) were the results of an inquiry conducted in less than a week.

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