“Unlocking the Secrets of the Moon: The Ingenious Strategies That Made NASA’s Historic Landing Possible”
Indeed, the strange-looking Grumman Lunar Module proved itself a solid and reliable flying machine, suffering only a handful of relatively minor failures throughout its career. For example, during the descent of Apollo 14’s LM Antares on February 14, 1971, the guidance computer began displaying intermittent abort signals. The cause of the fault was traced to a small ball of solder which had come loose beneath a control panel and drifted into a switch, shorting it out. Commander Alan Shepard and Lunar Module Pilot Edgar Mitchell’s initial solution – tapping the panel with a pen – worked at first, but the faulty signal soon reappeared. If the signal reappeared after the descent engine had fired, it would automatically trigger an abort, firing the ascent stage engine and sending the LM back into lunar orbit. Unfortunately, the guidance computer’s software was literally hard-wired in the form of “rope memory” and could not be altered in flight. Instead, software engineers at NASA and MIT came up with a clever workaround, which in simple terms convinced the computer that it was already in abort mode, preventing it from triggering an actual abort. Lunar Module Pilot Edgar Mitchell entered the fix into the LM’s display keyboard or DSKY with just minutes to spare, and he and Shepard made a successful landing – and for more on this and other heroic software fixes that saved NASA missions, please check out our previous video Where Did the NASA Expression “Steely-Eyed Missile Man” Come From?
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