Method to discriminate ICBM decoys? decoys are useless?

Ronny

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What are the methods to discriminate ICBM decoys? are they truly useless as stated by Stuart Slade?
I found that a bit strange since Patriot even have trouble discriminate the booster sections and fragment of SCUDs missiles with the warhead

Multiple Independently-Targeted Re-Entry Vehicles (MIRVs)

Why they exist Although MIRVs are often regarded as a development of MRVs, in fact they come from a totally different logic. In a ballistic missile site, the missile itself represents only a small proportion of the cost of the system (usually 10 - 20 percent). The bulk of that cost is represented by the silo and the command control system that goes with it. That cost is dorectly related to the number of missiles, not the number of warheads on each missile. Therefore, it is much less expensive to built 100 missiles with ten warheads each that 1,000 missiles with one warhead each. All the money saved can be invested in making the silos much harder and thus more difficult to destroy (meaning the enemy must fire more missiles at them to guarantee their destruction).

How it works The missile bus containing the warheads is designed so that it can make changes in its attitude and pitch between discharging warheads. It is then programmed so that, at the appropriate time, it can make those changes before discharging a warhead and can, thus, aim each warhead at a separate target. In theory it can aim all its warheads at different targets, in reality things are much more complex.

The problem is that the system has to discharge its warheads one at a time. It cannot discharge the whole lot at once. This puts a limit on how many it can discharge in the time available. Also, the degree of manoeuvering is strictly limited. So, the targets engaged by a single MIRV missile are limited toa relatively restricted footprint. Also, there are a lot more variable, many random and unpredictable, in aiming and discharging the MIRV bus which mean that MIRV missile-delivered RVs are a LOT less accurate than unitary RVs. So much so that if the launch distance is too far back from the target, the MIRVs are likely to miss by so much that they will be useless. So the distance at which the MIRV can discharge is severely limited. It should also be noted that the MIRV bus is very complex and very sensitive.

Effects on ABM MIRVs are also often promoted as a way of beating an ABM defense by "swamping it", apparently on the assumption that each descending RV would have to be destroyed individually. In fact, this is, again, not the case. Using nuclear-tipped ABMs, the relatively tightly clustered MIRVs would be taken out by a single shot. However, the simplest technique of eliminating MIRVs is, once again, to kill the bus before it discharges its warheads. This needs some extended range - the effect of MIRVs on the Nike-Zeus program was to upgrade the Zeus interceptor so that it had the range necessary to kill the MIRV bus before it discharged its warheads. That's why the range was increased from 250km (more than adequate to kill an MRV bus) to 740km (way more than adequate to kill any projected MIRV bus. Also, as a bonus, it needed only tiny amounts of damage or disturbance to render the MIRV bus ineffective. Far from being a way of beating an ABM defense, MIRVs were only credible in the absence of ABMs of adequate range.

Put in a nutshell, decoys don't work. That's about as simple as it gets. There are more than three dozen technologies available to distinguise decoys from real warheads. The decoy question was throughly investigated in the early 1960s and all the practical forms of decoy were discounted. By 1964, the decoy problem was essentially solved. Since that time, decoy developers have been trying to produce better decoys and the counter-decoy people have been devising ways of distinguising between the decoys and the real thing. At the moment, the filtration techniques are so far ahead that decoys have been discounted as a viable technique.

To work, a decoy would have to be exactly the same size, shape, weight, weight distribution, appearance, thermal characteristics and thermal distribution as a real warhead; if one's going to do that, why not just use a real warhead? By the way, before anybody repeats the old line "don't make the decoy look like a warhead, make the warhead look like a decoy", that was one of the earliest ideas that was tested. It doesn't work.

The British based an entire Polaris update around the use of decoys (it was called Chevaline). Chevaline ran years late and was horribly over-cost, the problems with the decoys being the primary and largest single cause of the problems. In fact, those problems were never solved. By the way, even using decoys from a ballistic missile is not as easy as it sounds; there's quite a few problems there that have never been solved either. Mostly because it wasn't worth spending money solving those problems when the decoys wouldn't work anyway.
 

Hanz2k

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First - he is talking about ICBMs not SRBM. If your system use nuclear warhead to kill Incoming warheads that decoys doesn’t matter. Just aim center mass and let 1MT warhead do the rest. For HtK system you need you need to discriminate warhead but ... looking from decoys perspective what you most probably encounter is inflating type decoy. In space it should have different thermal characteristics as real warhead. It cool down faster - if has some form of heating device then it will be not uniform as real warhead. Plus as decoy inflate you will see strange radar signal changes. This is what is basically stated in text - it is just better put another real warhead instead decoy that looks identical. Patriot has bunch of different problems with SCUDs starting with fire control clock issues.
 

Ronny

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First - he is talking about ICBMs not SRBM. If your system use nuclear warhead to kill Incoming warheads that decoys doesn’t matter. Just aim center mass and let 1MT warhead do the rest.
Nuclear warhead detonate at high altitude created a high altitude EMP that can blind the radar and destroy surface electronic system over very wide area. I believe that why US shifted from nuclear interceptor to HTK interceptor
empsideview.jpg
For HtK system you need you need to discriminate warhead but ... looking from decoys perspective what you most probably encounter is inflating type decoy. In space it should have different thermal characteristics as real warhead. It cool down faster - if has some form of heating device then it will be not uniform as real warhead. Plus as decoy inflate you will see strange radar signal changes. This is what is basically stated in text - it is just better put another real warhead instead decoy that looks identical. Patriot has bunch of different problems with SCUDs starting with fire control clock issues.
So as far as I know, there were 2 main ways to solve that:
1- Make the warhead look weird and various decoys are also at different size and shape
2-Put the warhead inside a metal balloon as well so that the heat signature aren't uniform
1.PNG 2.PNG
 

Nik

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IMHO, recent activity shows that if you can throw enough interceptors at in-coming, decoys are a waste of payload...

Like other forum members, I'd welcome Stuart's latest take on topic but, sadly, he was claimed untimely by Covid complications in late-2020.
 

Dilandu

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To put it simply, he is absolutely wrong.

* The accuracy of warhead deployment is linked only with accuracy of guidance system. While purely inertial systems on early ICBM suffered in accuracy from multiple trajectory changes, the modern buses have excessive accuracy. Some of them used external - astro-correction - references to correct the inertial systems mistakes.

* Warhead separation for ICBM starts quite early, soon after booster burnout. There are no practical reason to wait with it: the accuracy of warhead in vacuum depend almost soley on bus accuracy. So the majority of the trajectory warheads fly separated, surrounded with a cloud of decoys.

* While the early warheads could be potentially knocked out in a bunch by megaton-scale anti-missile missiles blasts, radiation hardening of warheads soon become commonplace, which means that even such powerful anti-missiles as Spartan would still require taking out warheads one by one.

* His idea that decoy must have the same mass as real warhead is just laughably wrong. The mass of both are insignificant in compairson with mass of Earth. The gravitation-inflicted difference in trajectory between warhead and empty warhead-shaped baloon is near zero. As long as warheads and decoys are in vacuum, their trajectory would be the same.

* While light (baloon) decoys could be discriminated at terminal phase by their slowing down in upper atmosphere, the heavy decoys (X-shaped in profile metal rods with radar cross-section similar to warhead ones) have roughly similar atmospheric properties as real warheads - and fraction of their mass.

In short: late mr Slade unfortunately have a tendency to assume his knowledge to be absolute, while it wasnt.
 

chimeric oncogene

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he is absolutely wrong.
The use of lasers and neutral particle beams to actively discriminate between decoys and warheads was extensively studied in the SDI era. With LIDAR, movement can be tracked down to the mm/s level or below. And a kilowatt laser can apply many micronewtons of thrust to an object.

Active discrimination makes it somewhat more difficult to hide a warhead inside a balloon, for one thing.

Defenses will likely be degraded by decoy at least a little, but it's the "how much" that matters.
 
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Dilandu

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The use of lasers and neutral particle beams to actively discriminate between decoys and warheads was extensively studied in the SDI era. With LIDAR, movement can be tracked down to the mm/s level or below. And a kilowatt laser can apply many micronewtons of thrust to an object.

Yeah, but it is not exactly what mr. Slade mentions. Nothing of it existed in working form in 1964. I agree, that lasers and particle beams may be a great way to discriminate decoys, but it is not what mr. Slade us talking about.
 

Trident

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None of it exists even today, really! Radar of various frequencies and IR is basically it, as far as sensors available for discrimination is concerned. LIDAR and visual spectrum EO are used for tracking of satellites, but I don't think either is part of any operational BMD system.

Some "heavy" decoys, designed to accompany the RVs into the atmosphere, of both Russian and US origin (the US decoy incorporates a jammer, the Russian one probably does too):

D-2Bx3sX4AAjcMh.jpg D_JBIweXkAEu4Fg.jpg

(H/T to the now-defunct twitter account @divert_thruster)

A counter to space-based defences as mooted under SDI (giving the opportunity of engaging the bus before RV deployment) which the Soviets hit upon was the so-called modular ICBM. This involved giving each warhead its own PBV or even upper-stage, re-introducing the multiple target problem even for an SDI-like defence.
 

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The thing is, we're getting lasers up and running right now, and all we need to do is switch from IR Continous Wave to UV-A Pulse (which is very likely over the next few decades). That means you'll get terminal missile defense for the pricetag of the wattage. Add the fact that modular fission reactors are becoming a thing... all you really need to win is a bunch of ground-side pulse laser stations hooked up to fission reactors.

Please note that we're getting impressive wattage pricetags right now. We're heading towards something along the lines of 1 USD/Watt if I remember right.

This kind of came up in my investigations for a future-history setting that I'm working on, and the only real 'counter' to this sort of set up on the tactical scale is 'casaba howitzers instead of omnidirectional because they have little to no warning time upon detonation'.
 

Dilandu

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The thing is, we're getting lasers up and running right now, and all we need to do is switch from IR Continous Wave to UV-A Pulse (which is very likely over the next few decades). That means you'll get terminal missile defense for the pricetag of the wattage. Add the fact that modular fission reactors are becoming a thing... all you really need to win is a bunch of ground-side pulse laser stations hooked up to fission reactors.
One problem. UV beams suffer tremendous losses in atmosphere. It absorbs UV spectrum quite well, much better than IR. So UV lasers may be used only as strictly vacuum weapon, fired from anti-missile satellites agaist ascending missiles, bus vehicles, or decoy clouds.
 

GruntFox

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The thing is, we're getting lasers up and running right now, and all we need to do is switch from IR Continous Wave to UV-A Pulse (which is very likely over the next few decades). That means you'll get terminal missile defense for the pricetag of the wattage. Add the fact that modular fission reactors are becoming a thing... all you really need to win is a bunch of ground-side pulse laser stations hooked up to fission reactors.
One problem. UV beams suffer tremendous losses in atmosphere. It absorbs UV spectrum quite well, much better than IR. So UV lasers may be used only as strictly vacuum weapon, fired from anti-missile satellites agaist ascending missiles, bus vehicles, or decoy clouds.
Not really, UVA is actually quite capable in the atmosphere. It's UVC that doesn't do well in the atmosphere. That is a very important distinction here.
 

RyanC

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Nuclear warhead detonate at high altitude created a high altitude EMP that can blind the radar and destroy surface electronic system over very wide area. I believe that why US shifted from nuclear interceptor to HTK interceptor
Actually, attenuation is much less than mythical "blind radar"

If you really are worried about radar blinding, build a second radar 200 miles away to look "around" any nuclear fireball.
 

Dilandu

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Not really, UVA is actually quite capable in the atmosphere. It's UVC that doesn't do well in the atmosphere. That is a very important distinction here.

And soft UV did not actually have much advantages over the visible light. Its worse in therms of atmosphere absorption, and harder to re-focus in vacuum.
 

GruntFox

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Not really, UVA is actually quite capable in the atmosphere. It's UVC that doesn't do well in the atmosphere. That is a very important distinction here.

And soft UV did not actually have much advantages over the visible light. Its worse in therms of atmosphere absorption, and harder to re-focus in vacuum.
The thing is, from what I understand, it isn't. It is also the only wavelength that the plasma sheath is transparent to (which is the absolutely hardest part of taking down a hypersonic object or, in our case, a reentering nuclear warhead). Yes, you might get (slightly) less range, but it is -from my readings- the only option we've got.

Also, please note that after you start getting into the megawatt range, atmosphere tends to not be a factor (laser-induced atmospheric vacuum for the win!).
 

zen

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Hmmmm....

Every gram spent on a decoy is a gram less for RVs with a warhead. Weight is still critical for anything trying to get up high and fast by rocket.

Heavy decoys = virtual attrition.

The most convincing decoy is a full scale RV with a lead warhead.

Vacuum at lo orbit is not pure, very low density Atmosphere exerts drag.

Density differences do produce results in relative V loss due to drag.

Mass has thermal inertia, even metal. Live RV has a thermal pattern a decoy must replicate or fail under modern IR sensors Resolution.

Stewart wasn't really wrong at all.
 

Dilandu

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Every gram spent on a decoy is a gram less for RVs with a warhead. Weight is still critical for anything trying to get up high and fast by rocket

Well, survivability of the warheads forced the solution. Mid-course inflatable targets are lightweight, and several dozens could be put just in remaining payload reserve.

Heavy decoys = virtual attrition.
No, because while they are indeed, heavy, they are also much lighter than actual warheads.


The most convincing decoy is a full scale RV with a lead warhead.
It is not practical.


Vacuum at lo orbit is not pure, very low density Atmosphere exerts drag.

Density differences do produce results in relative V loss due to drag.

But warheads did not travel in low orbit. ICBM warheads fly higher. So the difference between inflatable baloons and real warheads are just too small to be reliable.


Stewart wasn't really wrong at all.
No, he wasn't. You overestimate the ability of radars to track such a small differences.
 

tequilashooter

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Wasting a bunch of interceptors on a single ICBM seems to be the intention of what decoys are used for. If its doing than that than it is doing its job. EW can be used as stated by Trident, but I wonder if those decoys can be released to shield the missile itself with black particles by blocking views of radars below like they did with some of their sats. But we cant figure that out because newer generation ICBMs are mostly classified. https://www.thespacereview.com/article/3536/1

1625580023745.png

Have recent intercept tests take account for early maneuverability or using decoys themselves?
 
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Zoo Tycoon

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Hmmmm....

Vacuum at lo orbit is not pure, very low density Atmosphere exerts drag.

Density differences do produce results in relative V loss due to drag.

That can be fixed in the decoy, at least in the critical ABM launch zone, by including a drag counter balance solid fuel rocket. You need to add a candle (or spin motor) on each nasty, so their ionised trail has the same chemistry.

A “hard”, or “heavy” or “long fall” decoy can be made very, very challenging for the defence. Furthermore if a good level of security can be maintained around the decoy, the defence never quite knows if they’ve covered every last detail. The few moments available to find out is very short and horribly unforgiving.
 
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Dilandu

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Wasting a bunch of interceptors on a single ICBM seems to be the intention of what decoys are used for.

Essentially yes. The goal is to put a lot of targets (and chaffs, that confuse tracking radars) of which only a small numbers are actual warheads. Even the heaviest ICBM (MX and R-36M) could carry only 10-12 warheads. Decoys could easily increase this number to several hundreds warhead-like targets, making their interception economically impossible task.
 

Zoo Tycoon

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Have recent intercept tests take account for early maneuverability or using decoys themselves?
As far as I know, US ballistic missile defense was only tested on simple inflatable decoys that imitated only the RCS of warhead, but not the shape.

Several fully functional Polaris Chevaline bus’s were supplied to US following the system withdraw from U.K. service. This was to provide what was considered to be at the time a state of the art decoy test target for their BMD. These were not inflated decoys. I understand more than one has been flown but don’t know any details.
 

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That is until LIDAR comes into the picture, something that the USN has been pursuing rather heavily. That and the ever-increasing sensor density (which is literally heading to 'yes')... decoys wouldn't work as well, especially with UVA pulse lasers at anything of value...
 

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Ten years ago, I OCRed the Bell Labs ABM report.

Results of a study on nuclear blackout, conducted the previous summer by the Institute for Defense Analysis, concluded that since the blackout problem was significantly less severe at UHF than at VHF, the PAR frequency band should be changed to UHF. Largely as a result of this study, a joint decision between Bell Laboratories, the Army, and the Department of Defense shifted the PAR operating frequencies to the UHF band.

...

For older versions of NIKE-ZEUS:

The All-Target Processor was a digital computer that could process data on as many as 625 objects in a target/decoy cloud. The ATP used slowdown, scintillation, cross section characteristics of the objects to eliminate obvious decoys. The remaining objects had their data passed on to the Discrimination and Control Computer.

Oh, and it got data from the Discrimination radar in analog (video) form, and then encoding it into digital form. Ah, the good old days.

The Discrimination and Control Computer (DCC) could accept data on as many as 50 targets from the ATP. It did more rigorous (and I assume computationally intensive) slowdown/scintillation/cross-section tests. Once it eliminated those targets with characteristics of decoys; it generated a composite likelihood ratio for each remaining object.

The likelihood ratios, acceleration, velocity, and position data for all the remaining objects then got sent to the Battery Control Data Processor, where final decisions were made on what to engage.

The Battery Control Data Processor seems to be used in engagements where decoys were a possibility. It did all the engagement planning for #s of missiles to launch, on what trajectories and at what times to kill what object/objects.

It then passed final data on to the Target Intercept Computers.

The Target Intercept Computers did all the computations required to come up with guidance orders for the defensive missiles. Each TIC could handle six simultaneous engagements by time-multiplexing -- it divided each cycle of computing operations into six sections.

In case you wonder, the TIC had a mere 76.8 kilobytes of 'permanent' memory backed up by 12.8 kb of 'variable' memory.
 

RyanC

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The SAFEGUARD Data Processing System (DPS) had a peak throughput of 10 Million Instructions per Second (MIPS) with a data transmission rate to service the radar and other things on the order of 200 MB/Sec.

To put this kind of power in context...

Motorola 68000 (Sega Genesis Console): 1 MIPS @ 8 MHZ
Intel 386DX: 11.4 MIPS @ 33 MHz.
RAD750: 266 MIPS -- hardened to 2,000 to 10,000 grays for space applications (2001)
X-BOX 360: 19,200 MIPS (2005)

A lot of work was done with emulated SAFEGUARD hardware on IBM 370 Mainframes.

Software sizes were:

735,000 instructions for the real time software of the hardware
580,000 Instructions for compilers/simulator Software
830,000 instructions for Installation/Maintenance Software

2.5 million instructions written over 6 years.

In lines of code; I've found public references through google books for:

Safeguard:
2.2 million lines of code (ref 1)
2,261,000 lines of code of which 789,000 dealt with the real time system (ref 2)

Against this other comparisons are:

Space Shuttle: 7 million lines of code
Windows NT 3.1 (1993): 4 to 5 million lines
Windows NT 4.0 (1996): 11 to 12 million lines
Windows 2000: 29+ million lines of code
Windows Vista: 40 million lines of code
 

RyanC

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Also you can't just handwave "High altitude NUDETS to blind radars" for random reasons

Why?

Proceedings of the Special Projects Office Steering Task Group
Task II - Monitor the Fleet Ballistic Missile Development Program
45th Meeting - 30 September 1964 to 1 October 1964

"In the last few weeks, we have undertaken several studies which might interest you. The studies are made generally in response to requests from CNO. The most recent one is a study of providing the Mark 1 and the Mark 2 re-entry body or warhead with the ability to be fuzed at a very high altitude, as a precursor bursts at 200,000 or 225,000 feet. We have been asked to try to devise a very quick method to use for both systems, and then to study a sophisticated approach which would preserve all the fuzing options we now have.

"We have preliminary answers on the quick, unsophisticated fix and it was not as quick as I had hoped. The preservation of nuclear safety imposes some criteria which state that there must be sampling of two different kinds of environment unique to flight. We have considered, therefore, using a very low level G integrating device, or a vacuum sensor. These do not operate until you are well up in the exosphere. They have not been developed yet and will take an appreciable amount of time and money. As a matter of fact, it is thought that those two safety devices would be the pacing items in a quick fix and would take about 18 months. I think it can be done a little more quickly.
 

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Plus as decoy inflate you will see strange radar signal changes.

There's a lot of technical issues involving decoys.

You have to inflate it fast enough so as not to be rejected by the defenders as an obvious, slowly inflating decoy.

This means you need a thick, rugged decoy skin that can withstand the stress of rapid inflation.

Second is that you need some method to provide the gas for inflation.

If you try using compressed gas, as the gas expands to fill the decoy, it cools.

If you try using a solid propellant gas generator, the chemical reactions to generate the gas are going to be rather hot, particularly if you want a lot of gas volume generated in a short time to fool radar; leading to a rather hot gaseous interior.

Finally, in one test of the GBI interceptor, the entire mission was a "failure" because the target missile couldn't deploy decoys successfully. :eek:

If decoys were really a cheap and solved problem from the 1960s, how could decoy deployment failure occur?
 

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Mass has thermal inertia, even metal. Live RV has a thermal pattern a decoy must replicate or fail under modern IR sensors Resolution.

More to the point, Pu-239 has 1.9 watts per kilogram [W/kg] of decay heat. So you have between 9.5 to 19 W of decay heat generated for years upon years on the warhead itself as the weapon sits silently, waiting for the blue touchpaper to be ignited.
 

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You have to inflate it fast enough so as not to be rejected by the defenders as an obvious, slowly inflating decoy.

One little problems: defenders radars did not have unlimited range. All they could really say on the distances of warhead separation is "something warhead-like detached from the bus". At best. At worst, if the bus already deployed chaffs and jammers, your radars would report "big expanding reflecting cloud".
 

Dilandu

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More to the point, Pu-239 has 1.9 watts per kilogram [W/kg] of decay heat. So you have between 9.5 to 19 W of decay heat generated for years upon years on the warhead itself as the weapon sits silently, waiting for the blue touchpaper to be ignited.
Sigh. And how this little amount of heat supposed to be descriminated on the background of other heating? Warheads took quite a bit of heat while missile burn through atmosphere. Its MUCH more thah 9.5-18 W. Most importantly, it is not evenly distributed, so the actual heat of warheads would be quite different from each other.
 

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This actually touches on something I came across while researching CASABA-HOWITZER in that "doomsday weapons" thread last week. One idea that was floated under the name PROMETHEUS was a variant on the directional nuclear charge idea that would effectively work as a blunt-force decoy detection and elimination system. Instead of the focused plasma lance of CASABA-HOWITZER or a NEFP/shaped charge, you set your device up to be a wide-angle burst that fragments the cap plate into a cloud of metallic dust particles moving at up to 100km/sec. Point that at a reentry vehicle cluster as it releases from the bus and watch the trajectory changes, the real warheads should be minimally affected but decoy reflectors will be shredded or knocked out of the formation.
 

Dilandu

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This actually touches on something I came across while researching CASABA-HOWITZER in that "doomsday weapons" thread last week. One idea that was floated under the name PROMETHEUS was a variant on the directional nuclear charge idea that would effectively work as a blunt-force decoy detection and elimination system. Instead of the focused plasma lance of CASABA-HOWITZER or a NEFP/shaped charge, you set your device up to be a wide-angle burst that fragments the cap plate into a cloud of metallic dust particles moving at up to 100km/sec. Point that at a reentry vehicle cluster as it releases from the bus and watch the trajectory changes, the real warheads should be minimally affected but decoy reflectors will be shredded or knocked out of the formation.
Exactly. Essentially, its the same with lasers - while they aren't exactly good in knocking down warheads, they could burn out light decoys quite well.

P.S. Lasers also exellent as boost-phase killers - warhead bus is quite delicate piece of engineering. But it required a lot more power, still, than popping a baloon.
 

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Mid-course inflatables only work in the mid-course. Increasing density of atmosphere eliminates them by relative V change.

Heavy is still sapping available mass away from real RV numbers. Nothing avoids the mass fraction limits. Trade of RV numbers, RV size/weight, bus fuel. Choose which to sacrifice. You don't add anything for free.

Indeed a full scale RV decoy isn't worth it.

Time up beyond Lo Orbit is limited, thermal inertia countered by heater must replicate thermal distribution through the body in question. Inflated decoy doesn't have that thermal conductivity properties of a solid RV.
Metal conducts heat well, gas doesn't.

Overestimation of radar....
Three options,
1. Discrimination by penetrative very high band radar. Density of solid object produces different returns to thin film.
Hence for example Brimstone's MMW seeker. Able to discriminate between a truck, a car and a armoured vehicle.
2. Discrimination via higher band = more precise returns.
3. Discrimination via comparative returns (over time), accuracy increases per return. Ballistic trajectory is highly computable.
Atmospheric drag, known and computable.
As returns feed in, ever more accurate figures result and subtle differences revealed.
Time in this regard is still just seconds to minutes.

The best solution might be metal particles in an expanding gel, inflate around RV and decoy.
Variable density of gel and particles produces confusing returns and distorted thermal signature.
But mass of RV and decoy still produces different rate of change in V.
 

Dilandu

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Mid-course inflatables only work in the mid-course. Increasing density of atmosphere eliminates them by relative V change.
Yes. But since midcourse is the most lenghty stage - tens of minutes - protection here especially important.

Heavy is still sapping available mass away from real RV numbers. Nothing avoids the mass fraction limits. Trade of RV numbers, RV size/weight, bus fuel. Choose which to sacrifice. You don't add anything for free

Yes, a bit. But A - if you could trade one out of ten warheads for ten-twenty heavy decoys, it worth it. And B, with the limitations on numbers of deployed warheads by international treaties, it is perfectly practical to fill the space with additional decoys.

For example, Minuteman could deploy three warheads at most. Now, they all reduced to single warhead. Which neans that they could carry a big load of decoys, reliably hiding the warhead.


Inflated decoy doesn't have that thermal conductivity properties of a solid RV.
Metal conducts heat well, gas doesn't.
You seems to forget, that warheads are coated in the thermal isolation covering.


. Discrimination by penetrative very high band radar. Density of solid object produces different returns to thin film.
Require enormous energy, not reliable on long ranges, easy to confuse by just adding reflectors into the decoys.
 

Grey Havoc

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Finally, in one test of the GBI interceptor, the entire mission was a "failure" because the target missile couldn't deploy decoys successfully.
Though an awful lot of technical knowledge and expertise had been lost in the period since the end of the Cold War it has to be said.
 

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Sigh. And how this little amount of heat supposed to be descriminated on the background of other heating? Warheads took quite a bit of heat while missile burn through atmosphere. Its MUCH more thah 9.5-18 W. Most importantly, it is not evenly distributed, so the actual heat of warheads would be quite different from each other.

With this?
 

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RyanC

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Point that at a reentry vehicle cluster as it releases from the bus and watch the trajectory changes, the real warheads should be minimally affected but decoy reflectors will be shredded or knocked out of the formation.

Don't even need to count on that effect. Certain key components of nuclear warheads are voracious neutron absorbers. Guess what SPARTAN and SPRINT's warheads were?

Yes, that's right enhanced radiation warheads.

And you can't shield against neutrons easily -- at least not without significant mass penalties.
 

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