Can You Stop a Hypersonic Missile?

You know there is a pretty direct calculation to determine the theoretical best outcome. How close you can come to a maneuver-capable rocket, is the answer to a conic section that takes distance, and maximum speed of both rockets into account.

The purpose of a rocket is really only for distance to drop to something like 10 meters for conventional munitions and something like 300 meters or so for nuclear, in practice this is a constant.

So what matters is the maximum speed of both rockets. Make that large enough and you can get the attacking rocket to make maneuvers that (assuming they cannot be predicted), make it mathematically impossible to intercept the attacking rocket. In practice this difference is only something like 130 km/h (for nuclear).

Lasers won't work until we're talking gigawatt lasers, and even then only at "medium range" (in other words, for stopping nuclear weapons, an optimal outcome can only be achieved at single-digit kilometers, in other words, it may be able to protect individual points like the president, but it will never protect a city against a fusion device). Oh and whether a laser weapon works or not will not be known until seconds before impact. I hope you have strong nerves.

Note that the attacking rocket does not need tracking, it needs a good random number generator.

TLDR: no, we cannot currently intercept a hypersonic controlled rocket ... and that won't change without an overwhelming technological advantage, which basically means better rocket motors. At a sufficiently high equivalent level of technology, attacking rockets cannot be stopped. That level is only slightly higher than the level the US is currently at (and we don't know. Both US and Russia may already be past that point)

The end especially.

This really gave it away:

"So can you stop a hypersonic? Sometimes, the wrong ones. Probably not the right ones, yet. The one defense working against the right ones today is a politician’s restraint, not a kill chain.

The worst one is still in its silo. And we are running out of interceptors against the second-worst ones."

It sounds like ChatGPT talking to me.

It's weird reading articles written by AI or helped by AI because it's a lot of words but no overarching narrative. It's almost like an expanded and fluffed up outline. It's very exhausting to read and I lose interest partway through. AI written text has a low "ROI".

AI code is similar. The individual parts are OK but even after reading the entire codebase it's hard to understand how it all fits together or what the over arching structure is.

(BTW, I don't mind what you're doing at all -- as long as you're honest and upfront about it. I love how you're exploring this way of working. I also love the widgets you embedded. It's cute but doesn't add a ton to understanding of the ideas in the article but it's the type of thing AI can really enable for writers.)

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Detecting hypersonics is relatively easy because they are the opposite of stealthy. Even most glide vehicles have an initial ballistic trajectory that exposes it to many sensors at distance. The US field-tested a number of short range hypersonics since the 1990s that don't have a ballistic trajectory but those were all canceled.

Hypersonics have two related technical challenges.

They are not maneuverable, at least not in the way people imagine, due to fundamental limits of material physics. They are more "straight line" fast. This requires very fast reaction times on the part of defensive systems but the intercept is otherwise pretty trivial using the same off-the-shelf intercept terminal guidance from 20-30 years ago.

The big advantage hypersonics have is they significantly reduce the amount of space an air defense system can cover due to their speed. Hypersonic air defense missiles can counter this to some extent, which the US has, but these have drawbacks related to the second point.

Terminal guidance for hypersonics is an extremely difficult engineering problem because none of the physical materials you can use in terminal guidance systems can survive endoatmospheric hypersonic travel. A hypersonic missile without effective terminal guidance is an ICBM with a shorter intercept window. This isn't that useful for many targets.

The US has been continuously developing and testing different hypersonic terminal guidance designs since (at least) the 1980s. The first viable design only went into production 15-20 years ago. Presumably they've improved on and generalized it since then. There isn't much evidence that any other country has effective terminal guidance for hypersonics.

It is worth noting that effective precision terminal guidance was a prerequisite for US deployment of hypersonic weapons. Everyone else touting "hypersonic missiles" skipped that part.

Everyone keeps saying that Sprint was a nuke. That is true. However, it also scored some kinetic kills during testing at Kwajalein.

https://www.youtube.com/watch?v=YZZV464z9g8

I'm pretty sure that improvements in sensing, computation, actuation, and conventional warhead design over the past 50 years could have produced a reliable hit-to-kill Sprint. And in fact, some research was done on such a vehicle, the McDonnell-Douglas HEDI.

http://www.designation-systems.net/dusrm/app4/hedi.html