Magnetic guidance systems and intercontinental nuclear torpedos

[MrOmnos]

We see magnetic guidance systems everywhere. Migratory birds, whales, cruise missiles etc. Since, US invested billions in developing the GPS system and still spends billions every year maintaining it, tells me that those magnetic guidance systems weren't accurate enough or had very limited applications where as GPS systems can be used on almost every thing with great accuracy. North Korea just tested 10-30kt weapon. When you have 20kt weapon you don't need to be accurate. With the paranoid leader who just banned all forms of "sarcasm"  if they develop an accurate enough delivery system, I think the threat gets amplified 1000 times. So, In today's world where sensors and computers are getting better, smaller and cheaper how likely it is for a nation like north Korea to build a robust magnetic guidance systems to land a war head on a US west cost city. Let the delivery system be a vessel which travels underwater at a predefined depth and relies on magnetic navigation. When it reaches the cost it surfaces and get as near as possible to the beach and detonates. Are these intercontinental torpedoes even possible? Did anyone try to build something similar? I am pretty sure both Americans and soviets both must have thought about it at some point.

Note: No I am not paranoid.

[SeanB]

Very possible, though the accuracy depends on having a good map, and even better an inertial nav system that calculates position. The original Boeing 747 had a nav system that could, with only knowing initial position ( as in where the nosewheel was on the painted dot on the apron which was surveyed as the reference position for eg Heathrow terminal 1 gate 5) use that, along with a very heavily damped magnetic sensor in the tail, could accurately navigate the plane from Heathrow to Perth Australia with no additional correction inputs, and get there with a CEP of around 1km in position. Use closer points and you could get it smaller, but in all cases it was definitely good enough to navigate.

Major issue is the design of the low drift ultra precision gyro assemblies, which are not an easy thing to make from scratch. Most older missiles in any case also depended on other terminal guidance, like having a star tracker in the coast phase to refine position, using a few known stars in the sky. Others like the Tomahawk use a stored terrain map and a RADAR to get contour pattern and then fly a defined path, using GPS and INS over large stretches of water to get position.

submarines are easy to detect, the USA has a good number of hydrophone systems that run along the deep oceans approaching the shores, which can track the movement of ships just from the noise.

A submarine, unless it is nuclear powered, will have some large noisy diesel engines, and will spend most of the time on surface doing a better speed than the typical 5 knots submerged. Small yes, but trackable, and if sat recon shows no ship there but a big engine running then somebody will come looking for it, and then track it underwater with active probing till it surfaces from lack of power. If they detect neutron radiation coming from it ( hard to shield unless you have a few tons of Osmium shielding or similar DU shielding) they very likely will board, and then arrest the crew.

[dmills]

Neutrons are actually not a problem in this context... Thermalise them with water then soak the thermal neutrons up with boron (The nice thing about sea going transport is that **really** heavy is not much of a problem).

My suspicion is that the north Koreans are actually some way from a weapon plus delivery system that actually looks believable for hitting anything outside say the south china sea, at least as a missile, and we know they have reliability issues with their rockets.

Now a container routed via a very indirect route onto a Panamax scale container ship headed for one of the big commercial ports, that might be a different thing (But even a container full of ammonium nitrate would be a problem if set to blow while the ship was transiting the panama or suez locks it would cause all sorts of economic problems for the west), and you could do that with the aid of a couple of back handers to inspectors and a fake freight forwarding business.

People get hung up to the complicated and spectacular, when I suspect the real threats are very much simpler, just relying on good target selection.

73 Dan.

[MrOmnos]

Neutrons are actually not a problem in this context... Thermalise them with water then soak the thermal neutrons up with boron (The nice thing about sea going transport is that **really** heavy is not much of a problem).

My suspicion is that the north Koreans are actually some way from a weapon plus delivery system that actually looks believable for hitting anything outside say the south china sea, at least as a missile, and we know they have reliability issues with their rockets.

Now a container routed via a very indirect route onto a Panamax scale container ship headed for one of the big commercial ports, that might be a different thing (But even a container full of ammonium nitrate would be a problem if set to blow while the ship was transiting the panama or suez locks it would cause all sorts of economic problems for the west), and you could do that with the aid of a couple of back handers to inspectors and a fake freight forwarding business.

People get hung up to the complicated and spectacular, when I suspect the real threats are very much simpler, just relying on good target selection.

73 Dan.

Good point. I don't think North Koreans will ever hit US or any other country for that matter. Fat dictator is enjoying his life and wouldn't wanna mess things up. I think the real victims of those weapons are going to be the North Korean people. Dude banned 'Sarcasm" because he thought people were only agreeing with him ironically. I don't know for how long North Koreans are going to take this but someday someone will grow a pair and realize enough is enough. At least I hope so.  And in those situations insecure fatty will be the most dangerous man alive  with Nukes on his hands.

[G7PSK]

People get hung up to the complicated and spectacular, when I suspect the real threats are very much simpler, just relying on good target selection.

73 Dan.

That my thoughts on the matter as well, in many ways it a good thing that groups like ISIS are so hung up on killing people, if they spent their efforts on blowing up infrastructures like electricity pylons they would cause far more grief to far more people and pylons are not guarded and for the most part sit unobserved in field far from anyone so it would be very easy to blow up a whole string of them putting power out for weeks. 

[CJay]

That my thoughts on the matter as well, in many ways it a good thing that groups like ISIS are so hung up on killing people, if they spent their efforts on blowing up infrastructures like electricity pylons they would cause far more grief to far more people and pylons are not guarded and for the most part sit unobserved in field far from anyone so it would be very easy to blow up a whole string of them putting power out for weeks.

Three years or so ago the security services in the UK uncovered plans to destroy certain key motorway overpasses, for the volume of traffic involved it'd cripple the UK.

Pylons, not so much, you'd need a good knowledge of the UK grid, it's got some rather good redundancy built in and even if you did manage to knock out a city, it's possible to put in portable generation pretty quickly, key infrastructure already has it in place.

Far better to mess with the SCADA systems that link our energy management systems.

[Jeroen3]

Let the delivery system be a vessel which travels underwater at a predefined depth and relies on magnetic navigation. When it reaches the cost it surfaces and get as near as possible to the beach and detonates. Are these intercontinental torpedoes even possible? Did anyone try to build something similar? I am pretty sure both Americans and soviets both must have thought about it at some point.

The Nazis tried rockets. Didn't succeed very well though.

In order for your torpedo idea to be functional, the torpedo has to be silent and sonar deflecting.
Good luck with that.
Most rockets are designed to reach their destination asap in order to reduce action time when they're spotted on radar eventually.

[Kleinstein]

It looks like very reasonable to build a long range "torpedo" or unmaned submarine. For navigation they could still use GPS for most of the stretch, being just at the surface. A position so close to the surface would also hide from sonar - but make is visible to radar / cameras. If slow moving the military network might no detect it as a thread - quite some junk floating around undetected. With no need to be fast, they might go the last 1000 miles electric and quite.

There are a few tries smuggling drugs with small subs - so at least in the south the US is looking for such vessels and finds some, but not all.

Beside magnetics and GPS there are other ways of navigation, like the stars, gravity maps (is used in nuclear subs), sound.  They could also just follow or stick to a commercial ship.

Even if not reliable or long range, the north Korean missiles could still be a real thread to larger cities near by, like Seoul, Tokyo, or Singapore. It's already good enough as a deterrent, though nothing to start or even win a war.

[retrolefty]

"intercontinental torpedoes"

 We/they have them already, their called submarines. A torpedo with intercontinental range would need fuel storage requirements that one could hardly call them torpedoes unless the meaning is to state 'unmanned delivery system'.

[EmmanuelFaure]

Nice topic! I second retrolefty's words. It's a matter of scaling laws : Water resistance varies with the frontal area (Power_drag = 0.5 * rho * S * V^3), and energy storage varies with the volume. Other things being equal, the autonomy varies with size^(3/2), so a very large ship is naturally favored for long range missions. That's true for animals too.

[CatalinaWOW]

I'm not sure much accuracy is required.  While I can't imagine what the North Koreans think they might gain by detonating a nuke in an American city, I suspect that the US response would be about the same for a North Korean nuke detonated anywhere on the west coast.  Even at the most remote locations there would be a few deaths, there would be environmental damage, and radiation residue.  And the belief that the North Koreans would try again.  So even if it missed its target by hundreds of miles it would accomplish whatever it was going to accomplish.  Guidance would be the least of their concerns.

[fr0ster]

So, In today's world where sensors and computers are getting better, smaller and cheaper how likely it is for a nation like north Korea to build a robust magnetic guidance systems to land a war head on a US west cost city.

Sorry for my bad English... today sensors and computers and electronic components are getting better, smaller and cheaper, but a nation like north Korea do not can buy or make those thing. I hope they will not can do it forever, until they wise up. But still we must have to fear that someone else will sell them the details 

[MrOmnos]

So, In today's world where sensors and computers are getting better, smaller and cheaper how likely it is for a nation like north Korea to build a robust magnetic guidance systems to land a war head on a US west cost city.

Sorry for my bad English... today sensors and computers and electronic components are getting better, smaller and cheaper, but a nation like north Korea do not can buy or make those thing. I hope they will not can do it forever, until they wise up. But still we must have to fear that someone else will sell them the details 

They don't have to make it. They can just order it from digikey.

[Chris Mr]

There was a Daedalus (David Jones writing in new scientist) article about using heavy water in the nose-cone of a submarine.  At the surface the heavy water would be, more dense, so it starts to sink.  Then at lower, cooler, levels the heavy water starts to expand and look light again so it rises to the surface where it starts to get heavy again and so on - oscillating its way to the 'target'.  In the article he had a device in the nose cone to take a 'position fix' so it could adjust its trajectory before descending again.

It could be as many as two of the Daedalus ideas that actually made it to production 

( I just found the article in the second book - it was called "The diving Dutchman" - still laughing)

[CatalinaWOW]

While I am sure that Daedalus is alluding to water made mostly with the rare hydrogen isotope deuterium, the easy way to make "heavy water" in the proposed application is to add salt to it.  That wouldn't cause nearly as much concern among the credulous.  Much better to use a term associated with nuclear energy and spin up those who have heard the term without understanding the concepts involved.

[MrOmnos]

It looks like very reasonable to build a long range "torpedo" or unmaned submarine. For navigation they could still use GPS for most of the stretch, being just at the surface. A position so close to the surface would also hide from sonar - but make is visible to radar / cameras. If slow moving the military network might no detect it as a thread - quite some junk floating around undetected. With no need to be fast, they might go the last 1000 miles electric and quite.

There are a few tries smuggling drugs with small subs - so at least in the south the US is looking for such vessels and finds some, but not all.

Beside magnetics and GPS there are other ways of navigation, like the stars, gravity maps (is used in nuclear subs), sound.  They could also just follow or stick to a commercial ship.
Even if not reliable or long range, the north Korean missiles could still be a real thread to larger cities near by, like Seoul, Tokyo, or Singapore. It's already good enough as a deterrent, though nothing to start or even win a war.

I don't think US allows countries to use GPS for military purposes except for NATO of course. They have strict control over it but I don't know how US actually controls dangerous use of GPS system. Wiki doesn't help either. Very few info about it on the net.

[Red Squirrel]

I imagine if one analyzed ocean currents they could possibly figure out where to place something so it can drift about where they want it.  Would require less energy too.   Have it use some kind of ultra low frequency comms for telemetry/control. 

[MrOmnos]

I imagine if one analyzed ocean currents they could possibly figure out where to place something so it can drift about where they want it.  Would require less energy too.   Have it use some kind of ultra low frequency comms for telemetry/control.

LW would require lot of power for long distances. It would be a simplex comm.

[daqq]

I don't think US allows countries to use GPS for military purposes except for NATO of course. They have strict control over it but I don't know how US actually controls dangerous use of GPS system. Wiki doesn't help either. Very few info about it on the net.

To the best of my knowledge and very simplified:

GPS works by sending out a datastream. The trick is that the signal is very weak when you receive it here on earth. It's actually below the thermal noise. To actually receive it you need a trick called correlation. The datastream you wish to receive must be known before you actually receive it. You sample the signal you receive and correlate it against what you expect ( https://en.wikipedia.org/wiki/Gold_code ) and you get some ratio, which, if the code is present will be greater than if the code is not present. Depending on the finely adjusting the phase of the code you correlate with you can search for a maximum for your correlation. A correlation of random noise against anything is 0-ish. A correlation of a known signal against a signal that contains the signal at the incorrect phase zero-ish (assuming low self correlation). A correlation of a known signal against a signal that contains the signal at the correct phase, even if at insignificant power is higher than any previous case. 

So in order to actually receive the GPS signal you have to know what is being sent. Civilian GPS uses publicly available codes. Military GPS does not publish these codes and can change them at will.

[hamster_nz]

I don't think US allows countries to use GPS for military purposes except for NATO of course. They have strict control over it but I don't know how US actually controls dangerous use of GPS system. Wiki doesn't help either. Very few info about it on the net.

To the best of my knowledge and very simplified:

GPS works by sending out a datastream. The trick is that the signal is very weak when you receive it here on earth. It's actually below the thermal noise. To actually receive it you need a trick called correlation. The datastream you wish to receive must be known before you actually receive it. You sample the signal you receive and correlate it against what you expect ( https://en.wikipedia.org/wiki/Gold_code ) and you get some ratio, which, if the code is present will be greater than if the code is not present. Depending on the finely adjusting the phase of the code you correlate with you can search for a maximum for your correlation. A correlation of random noise against anything is 0-ish. A correlation of a known signal against a signal that contains the signal at the incorrect phase zero-ish (assuming low self correlation). A correlation of a known signal against a signal that contains the signal at the correct phase, even if at insignificant power is higher than any previous case. 

So in order to actually receive the GPS signal you have to know what is being sent. Civilian GPS uses publicly available codes. Military GPS does not publish these codes and can change them at will.

I am actually mid-way through building a GPS receiver (well everything behind the 2-bit ADC frontend chip.

Nothing stops people building their own receiver as now everything is digital it isn't that hard if I can do it. I'm just starting a blog on it at https://gpsdemystified.wordpress.com/

Commercial GPS modules must however have speed and/or  altitude settings built into the firmware to stop them from being put on a missile or something equally nasty. The high altitude balloon guys have found a model that only restricts with speed AND altitude, so that is preferred.

[fr0ster]

They don't have to make it. They can just order it from digikey.

I think they can not build navigation systems for military goals with electronic elements from digikey.

[fr0ster]

They don't have to make it. They can just order it from digikey.

I think they can not build navigation systems for military goals with electronic elements from digikey.

[MrOmnos]

They don't have to make it. They can just order it from digikey.

I think they can not build navigation systems for military goals with electronic elements from digikey.

I think they definitely can. Gyros and Accelerometers are cheap and probably more accurate than those used in 60s. They will have to isolate these sensors form the rockets vibration else they will go crazy. But I think it can be done. And they probably have good enough radar system. I think building a inertial guidance system would be pretty easy. The rocket would be the hardest part. You need a rocket that you can control with good accuracy and precision because being a meter/s fast or slow will lead to missing the target by a few kilometers. But hey why worry about few kilometers when your bomb's kill radius is 20 kilometers.

[max_torque]

The bigger issue is what happens AFTER some nutter nukes the USA.

even with that lunatic Trump in the White House, i suspect the retaliation would be excessive.

It's not called MAD for nothing you know........

[N2IXK]

I wonder if North Korea already has a last ditch weapon system in place. Remember that "satellite" they launched earlier this year that achieved a stable orbit but hasn't been observed transmitting any signals?

What if it were simply a canister full of gravel fitted with an explosive charge and a radio command detonator?  Something like that could make one hell of a mess in LEO, perhaps even enough to trigger the Kessler effect.