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Ken Shirriff

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

21 comments
Ken Shirriff replied to Ken

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

Ken Shirriff replied to Ken

I wrote a blog post that goes into much more detail on the Minuteman guidance system and computer, so check it out: righto.com/2024/08/minuteman-g
22/23

Ken Shirriff replied to Ken

Credits: many of the photos from National Air and Space Museum: airandspace.si.edu/collection- Minuteman I computer photo by Steve Jurvetson, CC BY 2.0: commons.wikimedia.org/wiki/Fil D-37C image courtesy Martin Miller: www.martin-miller.us. Diagrams from Minuteman Weapon System: minutemanmissile.com/documents Circuit board photo from bitsavers: bitsavers.org/pdf/autonetics/d Disk head assembly from LaserSam, CC BY-SA 40: commons.wikimedia.org/wiki/Fil Silo photo by Kelly Michals, CC BY-NC 2.0: flickr.com/photos/rocbolt/7372
23/23

Credits: many of the photos from National Air and Space Museum: airandspace.si.edu/collection- Minuteman I computer photo by Steve Jurvetson, CC BY 2.0: commons.wikimedia.org/wiki/Fil D-37C image courtesy Martin Miller: www.martin-miller.us. Diagrams from Minuteman Weapon System: minutemanmissile.com/documents

Giles Goat replied to Ken

@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" ? 😅

Ken Shirriff replied to Giles

@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.
For missile tests, they presumably have a self-destruct mechanism (same as rocket launches) so the Range Safety Officer can blow up the missile for safety if it goes off course.

Giles Goat replied to Ken

@kenshirriff Thought so, it breaks my heart to think all that fantastic tech destroyed in an instant .. 😢

illythekid replied to Ken

@kenshirriff Thanks for the interesting read!

the tower fairy replied to Ken

@kenshirriff came for the electronics, stayed for the typefaces :D so 60s

Dan 🌻 replied to Ken

@kenshirriff The technology is fascinating, and you've explained it very well, but promoting/sharing weapons of war doesn't feel good to me 😅

Chip Mason replied to Ken
Ben Brockert replied to Ken

@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”.

Jorge Peinado replied to Ken

@kenshirriff Absolutely fantastic post. Pure science and technology ( although much better to never see it in action :blobsweats: ). Many thanks for your fantastic posts !!!!

John Francis replied to Ken

@kenshirriff also...zero unintended or unauthorized launches (AFAIK)

Ken Shirriff replied to John

@johnefrancis Well, there were at least two incidents where the warhead was accidentally launched off the missile. Best known is the Damascus incident where a worker dropped a socket, causing a Titan missile to eventually explode, flinging the warhead hundreds of feet. There was also an incident where a worker was debugging the Minuteman silo security system. He pulled a fuse, bizarrely causing a retrorocket in the missile to ignite, flinging the warhead off the missile and it dropped 75 feet to the bottom of the silo.

@johnefrancis Well, there were at least two incidents where the warhead was accidentally launched off the missile. Best known is the Damascus incident where a worker dropped a socket, causing a Titan missile to eventually explode, flinging the warhead hundreds of feet. There was also an incident where a worker was debugging the Minuteman silo security system. He pulled a fuse, bizarrely causing a retrorocket in the missile to ignite, flinging the warhead off the missile and it dropped 75 feet to...

tyx replied to Ken

@kenshirriff @johnefrancis
Always think of these guys when I nearly miss a serious screw-up.

Stewart Russell replied to Ken

@kenshirriff @johnefrancis the 1964 Minuteman incident is written up here: armytimes.com/news/2017/11/04/

As for the Damascus incident, there's Eric Schlosser's whole book, Command & Control

Ken Shirriff replied to Stewart

@scruss @johnefrancis I heartily recommend the book Command and Control.

Stewart Russell replied to Ken

@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

root42 replied to Ken

@kenshirriff was the guidance ever upgraded or are those 400 Minutemen still running on this vintage technology?

Ken Shirriff replied to root42

@root42
The Minuteman guidance system was upgraded to the NS-50 in the early 2000s. The new system uses a MIL-STD-175A 16-bit processor. The Minuteman missiles are supposed to be replaced soon by the Sentinel, which is way over budget and delayed, so it's unclear when that will happen.

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