alt Hacker NewsFun fact:
The SR-71 and U2 planes had automated celestial navigation systems b/c GPS wasn't around when they came out.
There a story in the book about Lockheed Martin's Skunk Works where they mention turning on the system while one of the planes was in the hangar and it locked on to a hole in the roof (sun was shining through the hole and system thought it was a start).
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The sensor was sensitive enough that it could detect stars during daylight:
* https://theaviationgeekclub.com/the-sr-71-blackbird-astro-na...
* https://www.twz.com/17207/sr-71s-r2-d2-could-be-the-key-to-w...
* https://en.wikipedia.org/wiki/Missile_guidance#Astro-inertia...
The excellent CuriousMarc YouTube channel just started a new video series refurbishing a B-52 astrotracker, going over all of this in some detail:
https://www.youtube.com/watch?v=GkEjLqu-JH0&list=PL-_93BVApb...
Recommended.
It also immediately occured to me how much easier this should be on a copter, since you don't need a gimbal'd platform :)
I recently watched this channels videos on B-52 Astro tracking navigation system repairs: https://www.youtube.com/watch?v=nkvN74wuT8w&list=PL-_93BVApb...
He's got a bunch of other vintage electronics stuff that's from the early space program as well, interesting stuff to see the insides of that gear.
why would you think this has stopped? All military aircraft and missiles need to operate in gps denied environments and near universally have dead reckoning or celestial navigation still.
this makes me realize how lame GPS is, a centralized system that will take every thing down with it, should it ever go down
And, it's a bit older than that: the SR-71's derived from ICBM targeting systems,
https://en.wikipedia.org/wiki/Missile_guidance#Astro-inertia... ("the latter of which was adapted for the SR-71...")
(Actually the very first one, in that history, was an intercontinental cruise missile—a jet weapon that slightly predated (~1958) rockets powerful enough to cross oceans. ICBM's came a bit later. I'm pretty sure the first generation were pure-analog circuits, but I forgot where I read about that).