Gregory's ServerThe guidance system runs 24 hours a day so the missile is ready for immediate launch. On the ground, the system is water cooled; ground support equipment provides a chilled sodium chromate solution through the umbilical connection. This photo shows the coolant path through the computer and other components. 18/N
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24 comments
 A launch normally requires launch orders from two separate Launch Control Centers. But a single surviving Launch Control Center could launch the missiles, unless vetoed before a timeout. A complicated state machine managed the launch process. 20/N Although the Minuteman guidance system is interesting technologically, one has to keep in mind its purpose was to unleash nuclear devastation On the other hand, Minuteman has been successful as a peacekeeping deterrent (so far). In any case, it is morally ambiguous compared to, say, the Apollo Guidance Computer. There are currently 400 Minuteman missiles active, down from a peak of 1000. 21/N I wrote a blog post that goes into much more detail on the Minuteman guidance system and computer, so check it out: https://www.righto.com/2024/08/minuteman-guidance-computer.html  @kenshirriff Two "super stupid questions" .. actually one maybe a bit less stupid .. 1st question "Of course all that ( very expensive ) tech gets destroyed once the missile is launched ? I suppose when doing tests with no explosive they managed to recover it ? 2nd maybe less stupid have they ever had a "self destruct" thing to avoid such tech to accidentally end up in enemy hands if a missile launched failed to explode and could be recovered ? Maybe I am "too tinfoil hat territory" ? 😅 @gilesgoat Since the missile (and warhead) are crashing down at Mach 23 from hundreds of miles up, I don't think there would be anything left to recover. @kenshirriff Thought so, it breaks my heart to think all that fantastic tech destroyed in an instant .. 😢 @kenshirriff came for the electronics, stayed for the typefaces :D so 60s  @kenshirriff The technology is fascinating, and you've explained it very well, but promoting/sharing weapons of war doesn't feel good to me 😅  @kenshirriff This is a fantastic writeup, basically all of the ~1% of curious people in the space industry will end up reading it. As is often the case, the asides are many of my favorite parts; it feels very American to be specifically concerned about the environmental impact of your Global Thermonuclear War Machine’s cold gas thruster fuel. On footnote 8 there is a typo, “3000 km, even times the altitude”. @kenshirriff Absolutely fantastic post. Pure science and technology ( although much better to never see it in action :blobsweats: ). Many thanks for your fantastic posts !!!!  @kenshirriff @johnefrancis  @kenshirriff @johnefrancis the 1964 Minuteman incident is written up here: https://www.armytimes.com/news/2017/11/04/details-of-south-dakota-nuclear-missile-accident-released/ As for the Damascus incident, there's Eric Schlosser's whole book, Command & Control @scruss @johnefrancis I heartily recommend the book Command and Control. @kenshirriff @johnefrancis agreed. The whole thing starts with "You did *what* on top of two tanks of hypergolic fuel?" I think the moral of both stories is : go back to the damn truck to get the right tool  @kenshirriff was the guidance ever upgraded or are those 400 Minutemen still running on this vintage technology? @root42
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@Eupeptic I think the bar unscrewed and then served to hold the plug in place. |
The missile is programmed with launch codes through the Permutation Plug, a plug that holds the 48-bit code. With great ritual, an armed officer plugged it into the socket below. The launch code also depended on values on disk, so each Launch Control Center had a unique code for each missile. 19/N