Author Topic: The Computer Hack That Saved Apollo 14  (Read 5038 times)

Offline catdlr

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The Computer Hack That Saved Apollo 14
« on: 09/01/2017 03:39 am »
The Computer Hack That Saved Apollo 14

Scott Manley
Published on Aug 31, 2017

Apollo 14 almost never made it to the lunar surface thanks to a hardware failure which caused a short circuit in the abort switch. With the computer seeing the abort switch enabled the software team back on earth had a limited amount of time to figure out how to make the computer ignore the erroneous signal while still performing the landing. This required tweaking program state in memory while the program was running, a delicate operation with dire consequences for failure. No pressure guys.



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Offline Michel Van

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Re: The Computer Hack That Saved Apollo 14
« Reply #1 on: 09/01/2017 08:44 pm »
and next to that
The landing protocol in audio and video

« Last Edit: 09/06/2017 04:23 pm by Michel Van »

Offline Sam Ho

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Re: The Computer Hack That Saved Apollo 14
« Reply #2 on: 09/01/2017 09:47 pm »
Transcripts are here.  The ABORT button issue makes up about half of this page.  Discussion of the situation and the edits runs from 104:29 to 107:28, and the actual commanding is from 108:02 to 108:03.

https://www.hq.nasa.gov/alsj/a14/a14.landing.html

Offline markododa

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Re: The Computer Hack That Saved Apollo 14
« Reply #3 on: 01/25/2019 06:24 pm »
I couldn't understand the procedure fully, found a great explanation here https://www.hq.nasa.gov/alsj/a14/a14AbortDiscrete.html, but it doesn't say how did they start the ignition routine after setting the mode flag to P71 (ascent stage abort), nor how did they do it without rewriting the mode flag.


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