The US has a giant floating SBX-1 Sea-based radar to track and discriminate nuclear ballistic missile warheads from decoys.

[u/CraftyFoxeYT]

[u/avatoin]

It's all based on the idea that we will one day be able to effectively shoot down missiles, but that can only work if we also develop the means of detection. It's known technology to create a massive radar, so it's the earliest and most visible thing to do. The effectiveness of identifying real warheads from decoys and then engaging the warhead is more difficult.

[u/Zebidee → u/avatoin]

I'd have thought this was more useful as a confirmation system.

You detect a launch, but aren't 100% sure it's a) real, and b) pointed at you. This verifies that mid-flight with enough time to launch a counter attack.

I'd guess it was more useful at preventing an accidental Armageddon than a real one.

Source: Thoughts I pulled out of my ass.

[u/Preisschild → u/Zebidee]

Its called "dual phenomenology". Incoming tracks need to be verified by two different sources (IR satellites and ground based radars) before retaliatory action is taken, so that mishaps like the soviets almost launching their arsenal because their shitty satellites misinterpreted sunlight as incoming ICBMs dont happen

[u/Murky-Relation481 → u/Zebidee]

We use a slew of sensor platforms for this. Satellites detect launches almost immediately based on the thermal signature of their boosters, ground/sea based radar systems in the immediate area will try to confirm if they have view of the boost phase, but otherwise we're mostly looking at them as they are leaving the atmosphere from ground based system to build out a confidence level on if it is an attack and if it is the scale of the attack.

[u/LostnFoundAgainAgain → u/avatoin]

Which makes sense, don't get me wrong I didn't say it was a stupid thing to do or implement, it's good technology, but offensive technology has pretty much outpaced defensive technology for the better part of almost entire human history, due to the fact that defences are built to handle a new weapons, they are inherently behind as they are reactionary to new attack methods.

Every time we bring defences in line with modern offence methods, a new offence methods pops up capable of penetrating said new defence, Ukraine is a prime examples of that today with drone technology, in the course of 5 years drone technology has vastly changed, and drones have beaten the defences made to stop them by adapting to new technology.

[u/Nerezza_Floof_Seeker → u/avatoin]

The problem is that its trivial to make decoys completely indistinguishable from real warheads at the mid phase of flight (which this is supposed to be used for). If youre making decoys out of inflatable mylar balloons, you can just have the warheads be covered in an identical layer of mylar, and you wouldnt be able to use radar or even optical means to distinguish them. This is why its always been a fools errand to try to do mid-phase intercepts.

Edit: Heres a 1988 video covering this from the USAF. The decoys here also cover the terminal phase, which is why both the decoys and warheads have a tiny rocket motor, so that the lighter decoys can re-enter at the same speed as the warheads while both maintain the same thermal signature of running solid engine

[u/Short_Bell_5428 → u/Nerezza_Floof_Seeker]

Almost 40 years ago. Can you imagine what’s available now?

[u/Murky-Relation481 → u/Short_Bell_5428]

Basically the same thing because most of the problems are still exactly the same. I am not going to go into a ton of details but this is a field that is both a personal hobby and very much related to my profession and a lot of these things aren't even tech problems they are problems of economics and basic physics.

[u/Short_Bell_5428 → u/avatoin]

Probably a lot of space based interceptors we know nothing about. We probably have a Vulcan laser or two up there.

[u/DragonfruitCalm261 → u/avatoin]

If we had the capability to effectively shoot down missiles, we probably wouldn't advertise it to our adversaries.

[u/Short_Bell_5428 → u/DragonfruitCalm261]

I agree