Against atmospheric jitter, we have historically used ground radar, but it’s not clear to me this is even necessary depending on how much drone cameras improve. If the drone knows the exact position within 3 meters 0.5 second ahead of time (when the warhead is something like 2 km away), it won’t have enough performance to steer into the warhead, but it can throw a 1 kg explosively formed penetrator laterally at 2 km/s, which it would need to time with 0.1 ms accuracy. This would put 100 grams in each possible 1 m^2 cross section, though I’m not sure if it would work when spread out. To defeat this the warhead would either have to steer in the upper atmosphere out of range of the EFP of any available drone, or jink faster than the EFP can aim.
I thought that MIRVs were spin stabilized, but it looks like that’s not true, so in theory you could mount grid fins on them. However, any retrofit would need to handle the reentry heating which is significantly more intense than on manned spacecraft; RVs have thick ablative heat shields.
The chain of nukes plan seems possible with or without grid fins, so whether MIRVs still have cost advantage depends on the max altitude of cheap-ish terminal interceptors, which I really have no idea about.
I would expect aerodynamic maneuvering MIRVS to work and not be prohibitively expensive. The closest deployed version appears to be https://en.wikipedia.org/wiki/Pershing_II which has 4 large fins. You likely don’t need that much steering force
Against atmospheric jitter, we have historically used ground radar, but it’s not clear to me this is even necessary depending on how much drone cameras improve. If the drone knows the exact position within 3 meters 0.5 second ahead of time (when the warhead is something like 2 km away), it won’t have enough performance to steer into the warhead, but it can throw a 1 kg explosively formed penetrator laterally at 2 km/s, which it would need to time with 0.1 ms accuracy. This would put 100 grams in each possible 1 m^2 cross section, though I’m not sure if it would work when spread out. To defeat this the warhead would either have to steer in the upper atmosphere out of range of the EFP of any available drone, or jink faster than the EFP can aim.
I thought that MIRVs were spin stabilized, but it looks like that’s not true, so in theory you could mount grid fins on them. However, any retrofit would need to handle the reentry heating which is significantly more intense than on manned spacecraft; RVs have thick ablative heat shields.
The chain of nukes plan seems possible with or without grid fins, so whether MIRVs still have cost advantage depends on the max altitude of cheap-ish terminal interceptors, which I really have no idea about.
I would expect aerodynamic maneuvering MIRVS to work and not be prohibitively expensive. The closest deployed version appears to be https://en.wikipedia.org/wiki/Pershing_II which has 4 large fins. You likely don’t need that much steering force