And then there are MaRVs. Which is just a way to turn the considerable KE of the warhead into cross-range distance. Helpful if ABMs are expected at the other end. I want to say there’s a nuclear arms limitation treaty that prohibited MaRVs for either the U.S. or Soviet Union, but I’ve not been able to find one.
As far as guidance goes, AIUI, it’s still inertially-guided, with star-tracking to help fine-tune accuracy. In the case of the Trident D-5, the most accurate ICBM system I’m aware of, that gets you somewhere in the 90-120m CEP, and the rumors I’ve read is that it does better than that. I’m sure GPS’d be used if it still existed when countries were at the point of throwing nuclear-tipped ICBMs at each other. Hard to jam an internal set of insanely precise accelerometers and a telescope.
IRBMs/ICBMs/Cruise missiles that required still finer guidance back in the day, like Pershing II and AGM-86 ALCM, used some form of terminal guidance, usually a form of radar. The TERCOM system (‘Knowing where it is, because it knows where it isn’t’; a funny AF description of it can be found in this old missileer magazine, at page 5.) was supposed to be good enough to let the ALCM damned near split the uprights on an NFL field goal. From 2000+ miles away.
As for Pershing II, that you could get a radar signal through the considerable plasma sheath around an RV, and not only that, but get a decipherable return, was one of the more amazing features of the Pershing II when I first read about it. That, and a nuclear warhead that would still work after being shoved through 90-100 feet of rock at whatever the impact velocity was.
Wouldn’t be surprised if modern versions, especially those used for conventional strike, had something like Lidar or radar-homing or both. The more accurate the warhead, the smaller the charge needed to kill a hardened target, all else remaining equal. May not even need the nuke, if the RVs accurate enough.
As far as the MIRV bus and the shotgun analogy, doesn’t it actually make sense in an ABM environment, for the bus to get rid of the RVs (and the fake RVs and other penaids) as soon as possible? An RVs signature would be lower than all of them + the bus together, wouldn’t it? Also a given delta-V earlier in the flight means more cross-range separation at the end, which equals a bigger possible footprint for the MIRVs. I don’t remember reading that any of the current MIRV systems provide for in-flight retargeting, so why not send the warheads on their way ASAP, get them off the bus, and disperse them as early as possible?
Been a few of these kinds of threads lately. Everyone else as spooked as I am by news coming from the MidEast these days? (Saudis telling everyone they bought CSS-2s in the 80s, a missile so inaccurate as to be near worthless without a WMD payload; Bibi threatening unilateral Israeli action against the Iranian nuke program, which, given the depths the Iranians have dispersed/buried/hardened their facilities, will mean the action will likely be nuclear if it’s to be effective, and IMHO via Jericho 2 or 3.)
