Whole thing was a crapshoot, really. The entire ICBM complex, including the Soviet stuff, was a house of cards that would have probably created great disappointment for all the politicians concerned. Friend of mine who was intimately involved with Minuteman guidance work confided in me that he hoped WWIII never happened, because the aftermath was going to be monumentally ugly for those “steely-eyed missilemen” and their grandiose promises. He figured that we’d be lucky to get maybe 10% of the warheads near enough to a Soviet silo to create a mission-kill on their stuff, and that if the Soviets launched, given what he knew of their classified test data that he’d had access to, you could pretty much count on North America looking like it had measles. His take on their stuff was that it might be safer to be at ground zero in the missile fields than at some random location in the US or Canada…

This was, of course, all before GPS and the fall of the Soviet Union. When you look at the whole picture, you really start to wonder about it all, and the conventional wisdom about Star Wars systems–Say that they did manage to attrit 10% or so of the Soviet missiles: Considering the likely issues overall, that supposed “ineffective defense” might have made a huge difference in calculation for anyone planning an attack.

Thing that’s interesting to consider, too: Effect of weather on a launch. Everyone presupposes that a launch=hit, but when you look at the actual test data from launches from Vandenberg that include weather conditions like unexpected wind during the boost phases…? Suddenly, you start to wonder about whether or not the missiles would have even gotten out of the atmosphere on the way up.

We most definitely have a really skewed view of how effective these systems are, at least in popular imagination. The reality would likely be much different than we imagine, even today.

If I remember correctly SR-71′s had star trackers for a navigation fix.

I doubt INS needs gravity mapping. It would take the last known good GPS fix and integrate that into it’s psition.

Before GPS we had Loran which used a master station that would send out a radio ping and then slaves would respond when they got the master ping. By measuring the time delay, you knew where the stations were, you could get a fix on your position.

TERCOM was for cruise missiles. Mostly. From the early days until GPS came in, the whole thing was a house of cards, and possibly still is, in some significant ways. The vaunted “95% hit rate” for ICBM re-entry vehicles has only really been tested (for the US) firing from north-to-south from Vandenberg to the South Pacific test ranges with carefully overhauled missiles loaded with specialized custom guidance packages and then monitored by entire teams of controllers throughout the flight. Not at all what is going to happen during a “come as you are” situation during wartime, which in and of itself is going to mean drastically different results than we’ve all been taught to expect. With modern systems, this has hopefully changed, but who knows?

One reason that we never went nuclear during the Cold War was that nobody really knew what would actually happen. Most of the expensive tech was mostly so much BS on both sides that you couldn’t really trust much of anything. Fuck, we sold the Soviets most of the klystron switches they needed to make their bombs work, and we did that deliberately in order to give them enough confidence in their nukes that MAD could work and they wouldn’t try some other BS. The whole thing was a massive con job on the taxpayers in some very significant ways…

I’m confused. Isn’t that how TERCOM (terrain-mapping) navigation works? I didn’t think INS navigation worked that way.

It’s about like lightning strikes; weird and unexpected things happen to equipment and in the environment. The natural world is a hell of a lot more random than we would like to think, and the effect of EMP takes place in that world.

It’s a lot like the way blast waves propagate; sure, it’s predictable and somewhat consistent, but given some “unusual” meteorology, and you’re going to see things that you’d never predict or expect.

Friend of mine used to do EMP testing for the Navy; inside the lab, things were very consistent. They took what they did in the lab and went out into the real world to validate, and then things got very weird, very quick. Pumping that much electromagnetic energy into the environment can have some very unpredictable consequences, and we’re still babes in the woods when it comes to understanding it all.

Pretty much everything you read where they say “Yeah, everything electronic across the country died instantly…” is bullshit. There will be some really bizarre things going on–Say that they did do an EMP strike big enough to take out a lot of the infrastructure. Odds are pretty good that there would be some really weird eddy effects created by the various local conditions and the major electrical transmission lines, and if there were another Carrington Event these days…? LOL. Seriously unpredictable in the likely effects, other than that a lot of things would be royally ‘effed up.

Don’t buy the end-of-the-world hype. They sell it like it’ll all go down, but the reality is that we’re gonna get a ton of “unpredictable who-knew” sort of stuff.

Little-known fact about our ICBM force back before GPS: Accuracy was a joke, in the real world. When you trucked a missile to Vandenberg, overhauled it, and then put a carefully-curated guidance package into it that had been painstakingly mapped out down to the South Pacific test ranges, that did not indicate what sort of accuracy or reliability you’d see firing the damn things over the North Pole, in and out of the Van Allen radiation belts, and over terrain we did not have the gravity maps for…

The more cynical types who knew all the ins and outs of this stuff, being as they built it? They expected that maybe ten out of a hundred US missiles might hit near their targets, and that maybe one out of a hundred Soviet missiles would hit. Just thank God we never found out the hard way, because before GPS came in, odds are excellent that the map of the strikes coming in during the opening phases of WWIII would look a lot like some drunk with a set of darts was throwing them at a map…