The launching missile can carry dozens of penetration aids, each one needing an interceptor warhead.
Plus, the physical structure and fuel are by far the cheapest parts, it's everything else, guidance systems, maneuvering systems, etc., that make up the majority of the cost. Which each interceptor warhead needs but which dumb penetration aids don't.
Control systems are one per penetrator, aren't they? Same with nukes, if we're talking about them.
I'd say that it's exactly the fuel, the engine, and the whole chassis of an anti-ballistic missile what's so expensive. An ABM has very little time to do its job. It has to launch instantly, and accelerates at 100g or so, and then must also maneuver at this circumstances. It should also pack enough punch to destroy a warhead which is a relatively small metal needle, built to withstand the mechanical and thermal loads of an orbital reentry.
As a contrast, an ICBM can start with much more soft acceleration, can spend 10-20 seconds preparing for launch without loss of efficiency, and does not have to maneuver much during ascent and the orbital part.
No, penetration aids don't need any control system, they're literally just dumb pieces of metal. Of course they won't explode or be accurate at all, but that's irrelevant to soaking up interceptors which need to be a launched well before impact.
It's literally sending up some of the most sophisticated vehicles ever made by mankind to defeat mostly chunks of metal. Hence why even the US can't afford it in any meaningful quantities.
Everything on an interceptor is much more expensive because of the much higher performance requirements. But the fuel and structure will still be a lot cheaper compared to the rest of system.
Satellites in LEO and MEO can be destroyed with reasonably affordable conventional missiles nowadays, and it's impossible to hide or maneuver satellites in the few minutes it takes a missile to get up, so it doesn't really make sense to expect that any such system will survive long enough to do anything in a hot war scenario.
Hence why nobody really wants to weaponize space, spending money on military systems that have no survivability isn't very attractive.
Maybe you could cite a reference on the costs of these things instead? I'm just saying I don't buy it. They're both extremely expensive, but ICBMs, even accounted per warhead, are more so.
THAAD interceptors look to be ~$100M each from a google search. I remember seeing a leaked document that suggested up to 3 interceptors would be fired at each target to guarantee a kill, but I can't find the document now, sorry.
A Trident-D5 missile is $30M, and can carry up to 14 (small) warheads (which would likely be a mix of larger warheads and penetration aids). Trident is still in production, but note that it's an economical US missile.
So given this very approximate math, ~$2M on offense could soak up ~$300M on defense. The cost comparison would look worse for the defense if you don't assume the (high) cost of a US offensive missile for parity.
Wiki says that $800M gives you a battery of 6 launchers (each equipped with 8 missiles), 2 tactical centers and 1 radar. So the upper bound for one missile is 16M. Still very expensive of course, but not 100M expensive.
Pretty sure that price for D-5 doesn't include the cost of the W-88 warhead. I would assume at a minimum those would be $10M a piece. Still doesn't make it more expensive than THAAD however.
This is hilariously cherry-picked. THAAD is extremely expensive if that's the case. Wikipedia says you can get a Patriot for just $4M. Also SLBM's as actually deployed aren't using maximum MIRV counts, both for treaty and role reasons. Wikipedia says 4 RV's on average for Trident, FWIW. But the big whopper is that you're forgetting to account for the $4B SUBMARINE (just $200M per missile though) required to deploy those missiles in their cost!
Good job though. Honestly the numbers are closer than I'd have expected. But ICBMs remain more expensive.
I chose Trident because I wanted a fair(er) comparison of costs due to purchasing power. If you want to use North Korean ICBM pricing, it's $30M[1]. THAAD is very expensive, that you're right about...but it's also the only interceptor that has a chance of success against an ICBM. Please note as well, trident is typically deployed with far fewer warheads likely among other reasons because it doesn't need to be an interceptor sponge, per its role. If you're North Korea with a small arsenal, every one needs to count against an opponent with THAAD.
The launching missile can carry dozens of penetration aids, each one needing an interceptor warhead.
Plus, the physical structure and fuel are by far the cheapest parts, it's everything else, guidance systems, maneuvering systems, etc., that make up the majority of the cost. Which each interceptor warhead needs but which dumb penetration aids don't.