Hypersonic Missiles Are Unstoppable. And They’re Starting a New Arms Race | Hacker News Reader

Hypersonic Missiles Are Unstoppable. And They’re Starting a New Arms Race

nytimes.com

49 pointspseudolus14 comments

The mechanization of war caused a lot of wars simply because of the speed of attack it enabled.

As armies struggled to catch up to the new technologies, the mere act of mobilizing your armed forces was enough to start an armed conflict, because once your mechanized troops were massed somewhere, they could steamroll through a neighboring country before there was any chance to react. And so, countries began taking the mobilization itself as an act or war. This had catastrophic effect in 1914 when Germany demanded that Russia demobilize its troops (sent in support of Serbia) within 12 hours. This was a very short timeframe for the era, leaving no time for negotiation or airing of grievances, but it was a necessary one due to the newfound speed potential of mobilized armies. The result was World War 1.

ICBMs rekindled this problem, which is why people were so shit scared during the 60s, 70s, and 80s. Anything that allows you to neutralize your enemy's defenses before they have a chance to react increases the chance of their preemptively starting a conflict.

Unfortunately, the genie is already out of the bottle on hypersonics, and we'll just have to hope that we can reach a stable equilibrium before certain countries feel mortally threatened enough to start a huge war.

Killer AI robots, self-replicating automata, denuclearization (as it makes conventional wars palatable), renuclearization, rising nationalism and climate-attenuated resources scarcities are moving humans to the brink of genocide, civil/global/total wars and/or potential extinction.

Yawn. Always the same. The world hasn't been as peaceful as it is now in a long time.

As I understand, counter-hypersonics are the only defense to this, something not mentioned in the article. These are being developed already, though I'm unsure of success rates and what the odds really are of stopping a missile like this. https://nationalinterest.org/blog/buzz/mad-scientists-darpa-...

The key is really about detection, and having something capable of filling the space in front of the missile with stationary debris. The faster something goes, the more predictable the trajectory (due to the trumpet bell shape created by high velocity and constrained ability to accelerate), and the more vulnerable to damage from collisions with high relative velocity debris. There is a maximum speed that the missile can afford to shed if it uses either ramjet, scramjet, or ballistic via rocket based boosting + gliding to target, which further constrains the munitions evasive potential.

Definitely isn't something I'd want to defend against unprepared, but it isn't an unmitigable threat.

Can you speculate on the composition of debris or other material one would select to mitigate hypersonic threats? It seems that energy weapons would be ineffective due to weather attenuation and limited dwell time on the target at hypersonic speeds.

I'm absolutely no expert, but I would expect rr-188 chaff or similar would be sufficient, or even just the steel shrapnel from a missile exploding? Considering the speed/velocity involved I would assume any small, light debris could cause significant damage

Anything really. At the speeds we're talking about, you can basically look at the interception as being a very low altitude anti satellite strike since you have the same dynamics in play.

Any hypersonic projectile has to keep itself from cooking (heat shielding), and keep itself controllable. Compromising any of those attributes with current materials can be done with a bloody foam chunk (see the Columbia disaster). Just about anything that isn't gaseous, and happy with behaving as fluid is problematic at hypersonic speeds. Though I'd probably start at ball bearings or other types of flak just because of ease of manufacture.

If there's anyone bored enough, a frozen chicken impact simulation would be quite amusing to see.

The problem set you have to solve for successful payload delivery is basically the same as a reentering spacecraft. No one has really looked at doing something like this before, because the cost of slapping something like this together just to blow it up in the end as a tactical weapon has always been more on the prohibitive side compared to just finding better ways to get conventional weapons in place.

The only great innovation here is the innovation with which missile fabricators can dupe someone into buying yet more expensive missiles, and maybe some supply chain/manufacturing wins for some of the more exotic materials.

What I'm curious about is how good the navigation capabilities are, and the structural limits of the frame. Drastic course correction at Mach 5÷ has got to be absolute hell on the frame.

If you are talking about putting the debris in its path after observing the incoming missile, how can it be stationary? You would need to fire a counter-measure at hypersonic velocity into the projected path and have it detonate some cloud of debris (like a flak shell) so that its cloud expands the right amount for a high probability of collisions in the very brief time that the incoming missile passes through that space. Worse, the incoming missile is already at full speed and you have to accelerate yours from zero and still get it into the path. It needs to also go very fast, and so will have similar steering limitations as the incoming threat.

However, if you could create some standing network like a mesh of barrage balloons or on-station drones, perhaps you could avoid the need to launch into the path? You could transmit commands to pop a bunch of pre-positioned flak shells (or some kind of chaff with more hang-time?) in a spheroid patch of sky at a certain time. Of course, this means having a clearly defined theater where the targets and potential launch sites are far enough apart to feasibly deploy your virtual wall or dome of protection in the area in between. It also would be a bit like an ablative armor. Someone could probably focus an attack and exhaust the locally available counter-measures.

As salawat stated in the excellent parent post, >The key is really about detection

A cursory search indicates ICBMs have terminal velocity comparable to, or higher than, of hypersonic missiles, at about 16...34'000 km/h. The key difference is that a ballistic missile has recognizable launch signature -you can detect it via satellites- and coasts high above the atmosphere for several minutes, during which it's readily detectable by radar. We already have tech that reliably intercepts & destroys ICBMs - counter-rockets like Sprint/HIBEX [1], lasers, and even small nukes.

A hypersonic missile could fly low-ish [2], perhaps even "on the deck", thus evading long range radar detection. Still we could probably detect, from satellites, the heat signature of super-heated plasma around the missile.

I think the most stealthy -and dangerous- scenario would be a slow (trans-sonic, or maybe Mach 2) low-level cruise to mask the heat signature, followed up by a hypersonic dash to the target. Essentially leaving very little time to make decisions and launch counter-measures.

>If you are talking about putting the debris in its path after observing the incoming missile, how can it be stationary?

Relatively stationary. Dispersing several tens (or perhaps hundreds) of kilograms worth of small metal cubes or balls in area of a few hundred meters ought to be enough to hit a hypersonic missile with reasonably high kill probability. Basically old-fashioned flak, except delivered by a small rocket. The missiles own high speed would be enough to cause destructive damage upon hitting even small piece. This photo [3] shows effects of impact of tiny 7 gram particle at comparable velocities - some 25'000 km/h. A gaping hole like that in the heat shield would quickly lead to further damage in a hypersonic flight regime [4], perhaps also aerodynamic instability. And that's if the initial shock doesn't disable the mechanisms right away.

[1] https://www.youtube.com/watch?v=xZTjA44T6tY&feature=youtu.be...

[2] however low level hypersonic flight is very fuel-hungry, and causes tremendous heating; both significantly limit endurance

[3] https://en.wikipedia.org/wiki/File:SDIO_KEW_Lexan_projectile...

[4] https://en.wikipedia.org/wiki/Space_Shuttle_Columbia_disaste... was triggered by a small-ish hole of some 15...25cm in thermal protection

Is the big advantage of these is that they accelerate to these speeds quickly? Classic ICBM's are still faster on re-entry so these speeds aren't new but are slow and obvious on launch; if these things don't take a half-hour accelerating than they could prove revolutionary; however what I'm reading so far these still need to be accelerated by a conventional ICBM or aircraft, which means they are vulnerable to anything that can detect their launch vehicle meandering to launch speeds

Mach 10 in a few seconds. They accelerate at around 100g's

So, preternaturally fast.. It's a little scary just to watch on video.

> if these things don't take a half-hour accelerating

Ahem, a Trident II missile accelerates to 6km/s in less than 2 min, that’s more than 50g, see [1]

“When the third-stage motor fires, within two minutes of launch, the missile is traveling faster than 20,000 ft/s (6,000 m/s), or 13,600 mph (21,600 km/h) Mach 18.”

[1] https://en.m.wikipedia.org/wiki/Trident_(missile)#Trident_II...

Hypersonic missiles are unstoppable until that are stoppable.

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