# Counter ICBM question

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Hi!

I was looking up articles about counter ICBM measures for the last twenty minutes and they described existing efforts to consist of a detection system and counter missiles they use to try to hit the incoming missile and destroy it with the impact. The primary difficulty according to these articles is as the speed of the ICBM making it extremely hard to hit. I'm a complete layman who spent about five minutes on the problem, so I assume that the idea I came up with is completely infeasible and ludicruous, but I'm curious as to the science of why. Think of it as a thought experiment.

I'm making the following assumption: since the currently developed method is being tested in practice, it is possible to get kinda close to the target's trajectory.

The idea: instead of trying to hit the ICBM directly, scatter a cloud of matter in its path, let's say each particle being a 0.5 cm diameter disc bent to add air resistance, made from a high density metal. The location of the cloud wouldn't have to be impecably precise, as it would cover a larger area, the timing wouldn't have to be down to the prepostorouseth decimal digits since the cloud can be spread over time and it's density in the critical location changes in the order of magnitude of seconds. In essence this would turn the incoming missile's speed from a hinderance to an asset in destroying it before it hits its target.

Example with completely made up numbers: the detection systems picked up the ICBM and they calculate that it will pass through an area anywhere between time x seconds and x+1 seconds. The counter device, not necessarily a rocket, is launched. It begins shooting out the cloud at x-0.3 seconds, safely saturating the area (taking into account present wind conditions if within the atmosphere) by x, and keeps shooting metal until x + 0.5 seconds. For the remaining half a second the cloud is descending due to gravity and thinning out due to turbulence and wind, but maintaining a critical density long enough to last for until x+1. Somewhere within the time window the ICBM arrives, finding itself traveling at over 6000 km/s, being of several tons of weight and (I assume) carrying no armor plating and flies into a cloud of tens of thousands of few grams heavy, dense particles, which under these conditions shred it up, rendering it inoperable and if not completely destroying it, forcing it off course at the same time. The particles then keep falling to the ground at terminal velocity (low due to their shape), harmlessly landing to be sweapt up by whoever comes across them.

Obviously there's the danger that if the missile carried a nuclear warhead the radioactive matter would also land spread around under the impact site, but the same is true for the conventional method and while the initial path of the ICBM is set and there are limitations due to the time it takes to calculate it's path, the launch site and speed of the counter device and potentially wind conditions, there is still a degree of control over the area where it is taken down.

So, why is this stupid? Thoughts?

zoliking

Edited by zoliking
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It's not too stupid.

If anything, it's not "clean" enough.

Nike Zeus : https://en.wikipedia.org/wiki/Nike_Zeus

Quote

It was designed by Bell's Nike team, and was initially based on the earlier Nike Hercules anti-aircraft missile. The original Zeus A, was designed to intercept warheads in the upper atmosphere, mounting a 25 kiloton W31 nuclear warhead. During development, the concept changed to protect a much larger area and intercept the warheads at higher altitudes. This required the missile to be greatly enlarged into the totally new design, Zeus B, given the tri-service identifier XLIM-49, mounting a 400 kiloton W50 warhead. In several successful tests, the B model proved itself able to intercept warheads, and even satellites.

The idea is, you detonate one of the nuclear bomb in the vicinity of the target. It'll either explode too or evaporate.

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They call it shrapnel.

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Issues I can think of is you're probably underestimating the amount of stuff you'd need to reliably mission kill the missile. Then there's the size of the area. A second is a long, long time in this regard. You note that the missile is moving at 6000 km/s. Even a small miscalculation in where it's going to be means a large cloud of stuff needed.

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Basically, you just described how modern AA missile works. Both the counter missile and its target are relatively small and move very fast. Chances of direct hit are very slim. So, instead, as soon as the missile gets close enough to the target, its proximity fuse detonates the warhead liberally spraying the surrounding area with hundreds of high velocity pieces (shrapnel). Hopefully couple of them will hit the target, destroying it or damaging too badly to continue its flight.  Your idea is basically the same - only bigger. You would be trading quality for quantity.

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1 hour ago, kerbiloid said:

They call it shrapnel.

43 minutes ago, Xeorm said:

Even a small miscalculation in where it's going to be means a large cloud of stuff needed.

14 minutes ago, Scotius said:

So, instead, as soon as the missile gets close enough to the target, its proximity fuse detonates the warhead liberally spraying the surrounding area with hundreds of high velocity pieces (shrapnel).

Given the 400 kt used in Zeus B, I question that they intended to kill with shrapnel of any kind. More likely they just hope the shock would destroy it or if it's close enough it'll just evaporate or melt or something.

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We all referred to OP's post about a cloud of shrapnel strewn across the ICBM's path to intercept it, not your post about Zeus nuclear missile

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5 hours ago, kerbiloid said:

They call it shrapnel.

Actually, @zoliking, they call it a HОE.

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This exact method is used in point defense (think Iron Dome but scaled up) against cruise missiles. The anti-missile missile sends up a warhead that is packed with high explosive and a bunch of tungsten cubes about an inch wide. The explosive causes the tungsten cubes to spread out into a nice big cloud; it just takes one or two tungsten impacts to shred the incoming missile.

ICBMs are coming in much faster, from much higher altitude, and must be intercepted much higher, so this isn't quite as effective for ICBMs.

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Awesome, thanks everybody for the answers!

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1 hour ago, sevenperforce said:

This exact method is used in point defense (think Iron Dome but scaled up) against cruise missiles. The anti-missile missile sends up a warhead that is packed with high explosive and a bunch of tungsten cubes about an inch wide. The explosive causes the tungsten cubes to spread out into a nice big cloud; it just takes one or two tungsten impacts to shred the incoming missile.

ICBMs are coming in much faster, from much higher altitude, and must be intercepted much higher, so this isn't quite as effective for ICBMs.

ICBMs are also much "harder" -- they already have a reentry vehicle (RV) that can handle diving deep into atmosphere, reaching low altitudes while still at near-orbital velocity.  If you're passing through 20 km altitude at 5-6 km/s, a tungsten cube at near-zero velocity might not even penetrate the RV heat shield.

The nukes mounted on Zeus missiles were intended to "pre-react" the pits in the incoming nukes, preventing them from detonating on command by sharply reducing the quality of the bomb metal.  IOW, the shrapnel they spread (that mattered) was neutrons, and the damage done to the incoming warhead was on a subatomic level.  This strategy was used on ABM designs at least as late as the MX, and the "dense pack" strategy of the Reagan era amounted to letting enemy warheads do the same to each other (on the assumption that a time-on-target or MIRV attack on a dense pack site would bring the incoming warheads close enough together to damage each other or at least upset their targeting, too late in flight to correct).

Some newer systems used in ABM roles do rely on either direct impact, kinetic kill (like the flying windmill pictured above), or on "shotgun" or shrapnel strategies.  Based on my reading, these strategies are aimed primarily at IRBM and battlefield missiles (like Patriot against a Scud, or a point defense system against a smaller, shorter-range missile).  ICBMs are still too high and too fast, too hard to detect in coast phase, too far away during boost, so the strategy, left from the Eisenhower era (at least in part, because development takes decades) is still to nuke ourselves, high enough to do little ground damage, in order to mission-kill incoming warheads.

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51 minutes ago, zoliking said:

Awesome, thanks everybody for the answers!

And welcome to the forum.

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10 minutes ago, Zeiss Ikon said:

ICBMs are also much "harder" -- they already have a reentry vehicle (RV) that can handle diving deep into atmosphere, reaching low altitudes while still at near-orbital velocity.  If you're passing through 20 km altitude at 5-6 km/s, a tungsten cube at near-zero velocity might not even penetrate the RV heat shield.

The nukes mounted on Zeus missiles were intended to "pre-react" the pits in the incoming nukes, preventing them from detonating on command by sharply reducing the quality of the bomb metal.  IOW, the shrapnel they spread (that mattered) was neutrons, and the damage done to the incoming warhead was on a subatomic level.  This strategy was used on ABM designs at least as late as the MX, and the "dense pack" strategy of the Reagan era amounted to letting enemy warheads do the same to each other (on the assumption that a time-on-target or MIRV attack on a dense pack site would bring the incoming warheads close enough together to damage each other or at least upset their targeting, too late in flight to correct).

Some newer systems used in ABM roles do rely on either direct impact, kinetic kill (like the flying windmill pictured above), or on "shotgun" or shrapnel strategies.  Based on my reading, these strategies are aimed primarily at IRBM and battlefield missiles (like Patriot against a Scud, or a point defense system against a smaller, shorter-range missile).  ICBMs are still too high and too fast, too hard to detect in coast phase, too far away during boost, so the strategy, left from the Eisenhower era (at least in part, because development takes decades) is still to nuke ourselves, high enough to do little ground damage, in order to mission-kill incoming warheads.

My preferred nuclear point defense approach is to put a few megawatt chemical lasers in an inclined, eccentric orbit so that you have line-of-sight to your probable ICBM flight paths at all time.

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9 minutes ago, sevenperforce said:

My preferred nuclear point defense approach is to put a few megawatt chemical lasers in an inclined, eccentric orbit so that you have line-of-sight to your probable ICBM flight paths at all time.

I think the beam angle would have problems with that, not to mention the eccentric orbit means it's a sitting duck for the far away/active part.

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Does it rotate?

Spoiler
5 hours ago, DDE said:

they call it a HОE.

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22 minutes ago, YNM said:

I think the beam angle would have problems with that, not to mention the eccentric orbit means it's a sitting duck for the far away/active part.

Sitting duck? As in, it would be targeted by antisat weapons? That's unlikely.

Nuclear point defense these days is not really a question of repelling an extinction-level nuclear assault by a symmetric superpower, but of protecting native targets from a rogue state with a small rocket and a cheap nuke on top. Cough, DPRK. You only need a few satellites. Plenty of time, and 3-4 satellites means you have at least two sats with eyes on DPRK around the clock.

Beam angle shouldn't be as much of a problem in space as it would be for something like the YAL-1.

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51 minutes ago, sevenperforce said:

Nuclear point defense these days is not really a question of repelling an extinction-level nuclear assault by a symmetric superpower, but of protecting native targets from a rogue state with a small rocket and a cheap nuke on top. Cough, DPRK. You only need a few satellites. Plenty of time, and 3-4 satellites means you have at least two sats with eyes on DPRK around the clock.

Whether we're dealing with a minor power or a superpower is a very major caveat that has to be established at the start of any ABM discussion.

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3 hours ago, kerbiloid said:

Does it rotate?

Reveal hidden contents

Might have some rotation, but not much as you want it to be agile, note that standard missile 3 hit an satellite.  Interceptor has no warhead, it might have outriggers but if it has its probably smaller think antennas. Both speed and cross range speed would be higher than for an icbm. Yes aiming would be far simpler it was in an known orbit even if decaying and an larger target.

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6 hours ago, sevenperforce said:

Beam angle shouldn't be as much of a problem in space as it would be for something like the YAL-1.

... Except that YAL-1 had coverage of only a few hundred miles, your orbiting laser will be in the tens of thousand miles range.

That's at most 100x the circle of error/confusion.

You'd just have them destroying random stuff on the ground in addition to whatever the target is.

And by sitting duck I mean to ground-based lasers (if lasers are a go I bet whoever your rival is will have them too soon).

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For close range defence of ICBM silos they did look at swarmjet that threw unguided rockets into the face of incoming warheads, https://en.wikipedia.org/wiki/Swarmjet

Edited by Reactordrone
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And similar Soviet designs tested since 1970s.

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@Reactordrone, sounds familiar. Because, as @kerbiloid said, it's still quite alive.

ShPU Mozyr terminal ABM system appears to be the counter to the loss of survivability caused by reusing the very expensive missile silos over decades.

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14 hours ago, YNM said:

... Except that YAL-1 had coverage of only a few hundred miles, your orbiting laser will be in the tens of thousand miles range.

That's at most 100x the circle of error/confusion.

You'd just have them destroying random stuff on the ground in addition to whatever the target is.

And by sitting duck I mean to ground-based lasers (if lasers are a go I bet whoever your rival is will have them too soon).

YAL-1 was distance-limited because of the atmosphere; an orbiting laser has no atmosphere to contend with. It would target ICBMs during the coast phase, where they are well out of the atmosphere and their trajectory is predictable. Target tracking prevents collateral damage.

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46 minutes ago, sevenperforce said:

YAL-1 was distance-limited because of the atmosphere; an orbiting laser has no atmosphere to contend with. It would target ICBMs during the coast phase, where they are well out of the atmosphere and their trajectory is predictable. Target tracking prevents collateral damage.

Making long range lasers is not easy, you still have to focus the beam correctly, which takes significant hardware.  The best time to target something is the booster phase by far, since the object is extremely bright, very large, very fragile, and the atmosphere is not a problem once the altitude is significant.  The trajectory of a thrusting object is predictable, I have never heard of a vehicle that randomly adjusts its acceleration in flight.  Once the war heads are deployed, they are going to be highly resistant to your laser, since they are designed to survive reentry.

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