This was detected with VLF radio, but I wonder if this kind of event also has an effect on GPS signals? The time-of-arrival of astrophysical gamma rays isn't uniform across the earth.
What I wonder about is all of the technologies that go into ICBM's with nuclear weapons. My layman's guess is that there is active support and collaboration of the NK nuclear program from outside. North Korea is a headache for the US and other western powers, one more thing to consume policy bandwidth and military preparedness. This would seem to be in the interests of China and Russia, and perhaps others. I don't worry too much about the threats that periodically emanate from North Korean; if they start to exceed their utility from the perspective of China and Russia, the needed resources to maintain a viable nuclear program can be quickly shut off. I do hope that I will live to see a "1989" moment in which the North Korean regime is overthrown, and relegated to a horrible and sad footnote in human history.
While Russia and China don’t want to see North Korea collapse as existing nuclear powers they don’t especially want to see other countries acquire nuclear weapons.
Active support and collaboration came from Pakistan, Iran and Libya who were all trying to develop nuclear weapons of their own.
Well, these are multiple times more powerful. Not exactly last century's tech.
There are other factors too, like the sanctions these countries are under. One might say that some friendships were harnessed over common enemies, but I digress.
Remember that it took about 10 years for North Korea to go from it's first nuclear weapons test (which fizzled) to something that's probably a deliverable nuclear weapon, and they had spent decades before that to get to the first test. Nuclear weapons require great precision but they're not especially complicated devices. Any nation state, even the very poorest, should have no difficulty designing a nuclear weapon. It's the refinement of the design and the acquisition of the materials that is difficult, and even then the challenge is more in doing it clandestinely. Even then, the cost of the manhattan project, which not only developed two different nuclear weapons in 4 years, but also discovered a lot of the basic underlying physics from scratch, all in secret and with 1940s era equipment cost about $23 Billion adjusted for inflation. Similarly, the development contract for first American ICBM cost about $4 Billion in todays dollars. North Korea benefits from decades of scientific and technological advancement since that time, and it doesn't cost much to employ someone when you can throw their family into a camp, but even if we assume that it nevertheless would cost them as much to develop such technologies, over the course of 30 years that still represents a reasonably small fraction of North Korea's GDP. North Korea's long history of failures are pretty clear evidence that they were not given the design and manufacturing capability necessary to produce working nuclear weapons or missile systems. While no doubt there has been communication with other state actors over the decades, the idea that they are receiving active support is not at all supported by evidence, and indeed the embarrassingly long development time implies that either there is a great deal of incompetence in the development effort, active sabotage, or likely both.
GPS signals go through the ionosphere on their way from the satelites. The ionosphere causes distortions in the signal. If you want to achieve the best navigational accuracy you need to account for these distortions.
These distortions are not constant. They change from time to time. There are many different ways to account for them. One of the most accurate solution is to keep a GPS receiver on a well known location. Since you know that this receiver haven’t moved you can use the signal measured to estimate the parameters of the ionosphere between that station and the satelite.
Normally these signals are used to correct GPS navigational solutions. You take the closest station to your moving receiver and assume that whatever way the ionosphere was distorting for that station will do the same for your receiver too. This is valuable so there are network of such GPS stations in a lot of places.
Here they use the data collected by these stations differently. Instead of correcting a navigational solution they visualise the measured state of the ionosphere as seen by a bunch of these stations.
A simple GPS receiver will have a generic mathematical model for the ionosphere and use that as a good guess. More advanced ones can measure the delay directly.
The ionosphere affects different frequencies differently, so the GPS satellites transmits additional signals at different frequencies. By measuring the phase of these signals (L1 and L2), the math can be done to get a better estimation of the delay caused by the ionosphere between each satellite and the receiver. Those are the dots we're seeing on this animation. (GPS also uses the L2 signal to transmit encrypted information that lets military receivers get a better fix than civilian receivers).
> One of the most accurate solution is to keep a GPS receiver on a well known location.
I wonder if a network of connected devices with a GPS-disciplined SDR receiver and a regular GPS one could work both as this project does plus as passive radar like the software that was recently taken down. The purpose would be to have much wider coverage along with redundancy and error correction.
Such networks exist and make their data public. I think the equivalent you’re looking for is like LightningMaps, where there is real time reporting of observations instead of having to process recorded data to look back in time?
I worked on something like this in university. GPS bistatic radar. Two SDR frontends with directional antennas pointed in different directions to do various remote sensing, ranging, and other things.
The GPS network is essentially kept up to date with a few ground stations. The ground station is a source of truth that is used to send correction updates to the constellation periodically which are sent to all receivers.
But what are the moving dots in the animation? Planes, satellites? (seems to move like neither).
GPS being a military technology, I presume those fixed gps stations are only located in US-friendly countries. You wouldn't get that adjustment if you are flying over Russia or China, or any ocean. How much of an error in absolute distance are we talking about here? A few cm or meters or a km?
> But what are the moving dots in the animation? Planes, satellites?
Neither. The stations are in Japan. Imagine a line going from each of those stations to the satellite. Where this line crosses the ionoshpere that spot is what is measured. That is what you have information about. Those spots are the dots.
So you basically see the arc of the Japanese islands projected up towards each satelite which is visible from these stations. When the satelite is low on the horizon this projection seems to move fast, and when it is near the zenit it seems to move slow. This is what you are seeing with the dots.
They have a GPS receiver in a fixed, known location. They measure the received signal and from the variations infer corrections for ionospheric effects. They are part of the GPS network.
No. These are the receivers from japan’s GEONET.[1]
“Geospatial Information Authority of Japan (GSI) operates GNSS CORSs that cover Japanese archipelago with over 1,300 stations at an average interval of about 20km for crustal deformation monitoring and GNSS surveys in Japan.” [2]
Basically the government of Japan pepered their country with GPS base stations and they let researchers use the data from them. This is just a novel use of that data.
I would guess the moving dots are fixed GPS receivers, or more precisely the intersections of lines between fixed GPS receivers and moving GPS satellites with a sphere around Earth representing the ionosphere. If you look at the shape of the moving clusters, some look like Japan.
GPS receivers work by figuring out how far away they are from a number (>3) of GPS satellites. The receiver knows where the GPS satellites are (since the satellites broadcast their orbit parameters) so if a receiver knows how far it is from several satellites it can work out where it is itself.
Now, as the GPS satellite signals travel through Earth's atmosphere, they can be slowed down by different atmospheric effects. A slower signal will cause the receiver to think it's farther away from a satellite than it really is, so the receiver might estimate that it's position has changed a little bit. However, if you know the receiver's position hasn't change (maybe it's fixed in place to a big rock), then you can attribute the receiver's measured "change in position" to a change in atmosphere characteristics.
In this paper, they seem to have lots of fixed GPS receivers all over the place. By looking at all of them together, they can make a sort of map of the atmosphere characters in a part of the sky that's affected by rocket launches. The authors see these big ripples emanating from a Falcon Heavy launch in the US and this tweet shows those same ripples emanating from a launch site in North Korea.
You can go one better and filter your position data and store the data from the "worst fit" satellite. Which will usually be on the horizon or behind a thunderstorm, but not always, maybe it'll be behind a ICBM...
For made up simplified example, assume you have a moving GPS in an airplane or something, and there's exactly four sats N S W E. All four sats relatively agree you're flying the plane normally in a straight ish line as usual. Suddenly, the data from the S sat gets wildly distorted, but the other three sats remain normal. I suppose the S sat could have malfunctioned but more likely something is in between your plane and the S sat. So your navigation chip tosses the data from the S sat and marks its SNR way down and generally ignores that sat... However, if you were to log that "bad" data from the sat to the south... then compare to someone flying a plane a hundred miles to your south, and their GPS reports data suddenly was trash to their north, then you know something flew between your two planes. Maybe an ICBM, maybe a thunderstorm, maybe a GPS jammer weapon, a lot of "it depends". Sometimes its the data thats tossed out thats the most interesting.
I've been fooling around with something a LOT cruder at home WRT tracking thunderstorms. Its not rocket surgery to know that severe rain attenuation can impair GPS signals. One of the standard NMEA output lines contains each sats SNR, so if I know from my "vast" database that in normal weather satellite #43 at az 45 degrees elevation 45 degrees reports a SNR of made up number -10 plus or minus 2 over the past few years, then if it reports -20 today that would imply either the sat just burned out (unlikely) or there's a rain cloud causing "about 10 dB attenuation" at az 45 degrees elevation 45 degrees relative to my house. The linked project in the article is enormously fancier of course than merely logging SNR fluctuations.
I'm amused at the idea of crowdsourcing a "large amount" of forest hiking data over time to evaluate the health of the tree canopy in forests. Where I live the leaves are all down now so GPS signals should be very strong for hikers in forests.
As the Air Force discovered decades ago, for various EE and trigonometry reasons, bistatic radar works best overhead its kind of the opposite of what you want for an early warning radar so you can see why bistatic radar never went much of anywhere compared to traditional radar for the usual Air Force mission purposes. Although there are interesting modern "IoT" distributed sensor applications, at least if you have unimpeded fast communications systems, etc.
Fun house mirrors are curved and distort your reflection.
Some fun house mirrors are flexible so they can get pushed or pulled which will make you look taller or shorter or fatter or skinnier than you know you are.
By observing the difference between how you appear compared with how you are;
you can learn something about how the flexible mirror is being curved.
How this works in the fun house is there is you the mirror and LIGHT.
Both you and the light are well known and easy to predict; light will travel straight(ish) and you will not suddenly become very very short, so the thing that is changing your appearance is the flexible mirror.
In the GPS rocket case,
the GPS satellites are the illuminating source corresponding to the light in the room sending out radio (electromagnetic radiation same as light just at longer wavelengths)
The ground station GPS receivers correspond to your eyes (they know what they *should* see).
The earth's ionosphere corresponds to the flexible fun house mirror.
taken together, the same way you could tell if something we can't see behind the mirror flexed it, the author of the post showed they can tell if, when and where
an unannounced rocket goes through the ionosphere.
I don't think I could explain it to a small child, given that I don't have a great understanding of it myself. But here's what I could scrape together based on a linked paper[1]:
You use GPS receivers to detect ionospheric disturbances. Ionosphere, coming from the word "ionized", means it consists of charged particles, positive or negative. (Missile) exhaust is mainly neutral molecules, creating a "hole". These ionospheric holes can be detected through the Faraday Effect[2]. By measuring the Faraday rotation of radio signals (like GPS), you can detect these holes. I think this is similar to how polarized light 3d cinema systems work, except it's the radio spectrum instead of light.
As you walk past a school you yell with your voice, your friend nearby knows what you sound like but he hears you differently because your voice also bounces off the school wall. He adjusts the sound based on what you should sound like, the leftover bit is the shape of the wall.
You can figure out if someone moved a brick (or launched a missile) because your voice changes when it reaches your friend and he needs to apply a new change to get your voice back.
We can see the signal changes the rocket causes to the ionosphere and know that it's happened.
Isn't the ionosphere already past the burn-out phase of a ballistic missile? I.e. by the time the rocket gets there it is just a glorified harpoon. Or perhaps that doesn't matter as anything of this size travelling at this speed would cause detectable disturbance?
Fun fact: the arecibo radio telescope was funded to study ionosphere disturbances so the US military could explore the possibility of detecting ICBMs passing through the ionosphere. To my knowledge no such system was actually built but apparently it wasn't as ridiculous a proposal as I thought.
They don’t really seem to have a detector. They have a thing which makes visualisations, and it seems it should be possible to build a detector on top of that, but that doesn’t seem to be done yet.
Yeah, we had a detector with some ML stuff, it worked okay, but the main issue is there isn't much training data.
Overall the false positives are quite low (visually, which is hand wavey, of course). I've not really seen a big event that was not real. I ran it for a while 24/7 and while there are "scintillations" there aren't any circular waves. False negatives are a much bigger issue. Something like an IRBM or SRBM doesn't really show up, and those are much more common.
Fwiw, this uses a bandpass filter to look for the ripples, which filters out a ton of noise. Looking at ionospheric depletion would be good and probably more sensitive, but it requires accurate models of what the ionosphere ought to do. I've tried a few things there with mixed results.
The main protocol is called NTRIP. Lots of sources make it available (though it might be annoying to stream from ~250 simultaneously, not sure). There's a lot if you search that term though.
I think GEONET (the Japanese data source) might have some NTRIP casters. Also some in Korea and elsewhere. Sometimes you have to pay for access though, so I need to look more.
The problem is that NK has thousands of traditional artillery pieces stationed along the DMZ that are capable of hitting Seoul and other large population centers [0]. They also have short range ballistic missiles [1] which can reach much of South Korea.
So negotiating with them has been dicey. Especially since they have figured out that "If we do this thing the west doesn't like, we can go to the negotiating table and get them to send us food."
I do want to point out that the war never ended in 1953 - there was just an armistice signed, so technically North and South Korea are still belligerents.
So far as the DPRK leadership acting rationally - by their standards, they are. From talking with people who have visited there - the North Koreans have a world view that is substantially different from everyone else on the planet.
Even assuming it's not already too late for that: what could they do? NK is already sanctioned to the max. And the few leavers that they can still pull probably wouldn't be enough to stop them at this point. And them being so close to China and SK makes any direct military action against them likely to trigger WW3.
If JP/SK/US did decide on military action against North Korea, I would expect China to stand back, close their border, and do nothing but make loud protest noises. They're not keen on sharing a border with a US client state. They're also not keen on a rogue North Korea with nukes.
The main issue is that, even without nuclear weapons, North Korea has enough conventional arms, including chemical weapons, to cause horrific damage to South Korea. Seoul's entire urban area is within artillery range of the DMZ. I've seen estimates of varying credibility but most experts speak of hundreds of thousands of deaths on the first day of shelling, if a full-scale war broke out on the Korean peninsula.
I know quite well, as you probably do, that international law has zero bearing on the military decisions made by the USA in terms of its interests. Yes, it'd be illegal, unless the UN Security Council gave its blessing. Just like the second Gulf War was illegal. That has never stopped the US before.
> How does it correspond with "we are the nation of laws"?
It does not. The United States government rejects the idea it is restricted by international law on these matters.
As for South Korea, it can argue it's an internal domestic matter.
“Illegal war” is just a phrase to make political noise about military action you don’t like.
There are treaties, not laws, and no body to actually enforce laws, it’s just diplomacy. General practices are agreed upon but they’re basically just loose agreements.
I have been wondering: is North Korea an example of sanctions not working or having the opposite effect? By sanctioning North Korea to the moon and back, they have no other choice but to bottle up, tighten the hatches, take an authoritarian stance, deal with people willing to do deals under the table, and search for ways to strike back. Since they don't have the capability of building a traditional military force, they go for the biggest thing they can: nuclear missiles. Meanwhile, their people starve and suffer.
Are there not alternative policies that would work a little better? North Korea just seems like a cornered badger and will continue to act like one. If you "opened" up the country by reducing some sanctions, it seems they'd have to adapt to be more civilized. These are more questions than statements.
What is the end game with North Korea though? It seems the only options are:
* It collapses on its own or there's an internal revolution or coup. This would be a mess though because of the whole China, Russia, South Korea claims probably.
* It does something drastic and attacks and then gets invaded. That also seems a mess because now it's China, Russia, South Korea, and the U.S. and maybe Japan, depending on who it attacks.
It's complicated because states diplomacy exists in a condition of pure anarchy, but "disarmament in exchange of security guarantees" is another option.
One might draw parallel with Ukraine, which is fair, but turns out it wasn't USA the untrustworthy party to the agreement, and they didn't get a defensive alliance out of it, which showed to be a necessity and raises the bar considerably
Lets speculate a little bit for argument sake. Take this with a grain of salt because I am not a specialist, just a information hoarder.
Lets put miniaturization aside and focus on another aspects, which i judge will be more critical.
The warhead must survive mechanical stress of launch and reentry, and thermal stress at reentry. The question is: can it be designed only with computers and public knowledge? They could build small hypersonic wind tunnel to collect data and simulate the rest.
Randomized link goes to an except of North Korea's "Korean Central TV" where NK announces their Hwasong-17 launch. It's in music video style, make of that what you will, and seems to contain a fraction of the information at <https://en.wikipedia.org/wiki/Hwasong-17>. It is not clear to me whether this was actually tested with a nuclear warhead, the video doesn't get more concrete than "[this is] a reliable nuclear war deterrence means" which could just mean it deters nuclear war, not that it's nuclear in itself. I don't know whether this supports the claim that it is "really" nothing new.
They very likely already have that.. they’ve detonated >50kt nukes and have mobile ICBM launchers that have demonstrated rockets with thousands of miles of range.
They could almost certainly detonate a nuclear weapon in Korea or Japan. I’d put even odds on a strike on Guam, but probably not quite capable of hitting Western US.
Yes, there’s no doubt. They’ve tested multiple devices, several of them failed but the 2017 one didn’t. We know they bought the designs and materials from Pakistan, we’ve seen enough images of the process and equipment to know they were actively making progress, and we can measure the size of explosions via seismographs. We can measure the craters left behind via satellite images.
More valuable, in any rational sense of the term. Having them without anyone believing that you have them is more or less useless. Their only purpose is deterrence (unless you have a death wish for your population, and there are easier methods available if that's your 'use case')
Just to add a little context to this comment, the world's foremost nuclear power (the USA) runs live-fire exercises every year where its army practices invading North Korea. Under these circumstances, it's entirely rational for the NK government to develop nuclear weapons.
If the US government really wanted to stop this, it could offer a good faith deal for disarmament involving some kind of reduction of sanctions or normalization of relations.
Instead US politicians prefer to hypocritically hand-wring about other countries' nuclear development while maintaining a massive nuclear arsenal to threaten every other country, and while invading or bombing other countries on a regular basis. These are the actions that cause states to feel threatened enough to pour enormous resources into nuclear weapons development.
> live-fire exercises every year where its army practices invading North Korea
It's "practicing invading North Korea" in the same sense North Korea's missile tests are "practicing dropping nukes on America." It's a war practice, all options are on the table, with the hope that they won't be necessary.
> It's "practicing invading North Korea" in the same sense North Korea's missile tests are "practicing dropping nukes on America."
The context here is extremely important. All of this (the invasion exercises, the missile tests, the Korean War) have taken place in the Korean peninsula. None of it has threatened the US homeland in a meaningful way.
In addition, the exercises have been going on since 1997. That's a long time before any missile tests were conducted. If the DPRK (North Korea's name for its state) had been testing nukes from Cuba in 1997 I'd feel differently. But note that even dropping live bombs on other countries is something the US gets to do without starting a war because the US military is so powerful. Very few other countries operate that way and North Korea certainly isn't one of them.
I don't know if you're aware of it, but your framing is uncomfortably close to the North Korean diplomatic position, where it pretends that it's a matter to be settled between NK and the US, and any other countries are bystanders. Conspicuously absent is yet another country that will be directly affected by any conflict. Where do you propose the South Korean military conduct its joint military exercise to defend itself from North Korea? Texas?
(Of course, the official North Korean propaganda is that South Korea doesn't matter, because it's merely a colony of Imperialist America, to be liberated by our brave northern brothers. How nice of them.)
> the exercises have been going on since 1997.
North Korea has been caught developing nuclear weapons as early as 1992, which led to it threatening to withdraw from NPT in 1993. It's a shitty situation with decades of history, and you could easily find plenty of things to blame on both sides. But interpreting it as the US threatening to invade NK is a pretty biased take.
>Missiles make ionospheric disturbances that GPS records. The yellow ripple is the ionospheric disturbance.
Where can I read more about the meta level concept of "isopheric disturbances"? (Because I suspect I'll find this has been done by military intelligence for a long time then rediscovered by so called "arms control" wonks who insist on putting their code into the public domain.)
>You say that as if there is something wrong with that.
So to be clear, you an arms control expert public domaining code that aids totalitarians like Putin and the North Koreans has... "nothing wrong with that"?
Some domain specific knowledge was meant to be esoteric* and there are a variety of better licenses such as CC-non-commercial that allow peaceful uses of the code without allowing it to be used by literally anyone on the planet.
(*Unless you pay the proper fees, of course. But that's not just about money... you have to earn the right to make the purchase.)
To do anything about incoming missiles, you'd need extremely low latency tracking, integrated into whatever system you're using anyway. Not sure exactly you'd be worried about even if this was near-real-time.
Wild! I don't think I've ever seen someone who thinks restricting tech like this is actually a good idea. I thought that was just like, crazy government people who don't understand technology.
I'd hoped we'd moved past printing the entire code of PGP in a hardback book in an OCR font but I guess y'all still out here.
> and there are a variety of better licenses such as CC-non-commercial that allow peaceful uses of the code without allowing it to be used by literally anyone on the planet.
I don't have a fully formed opinion on the rest of your comment, however I can definitely point out that software licensing on open source software will not stop a nefarious third party from using it. They're nefarious!
To a practical point though, information asymmetry is powerful in war, but the cat was already out of the bag for this technology as it's in public papers. The code is just an application of information that was already public, they could probably write their own version of the same code based on the papers.
> code that aids totalitarians like Putin and the North Koreans has
This is false. Putin is not afraid of shining a very bright radar into the sky to know when missiles are about to hit them. That is the standard and reliable way to go about this.
Have you heard about the “woodpecker” signal? It was the transmission of a giant over-the-horizon early warning radar system. It is now defunct, has been replaced by more modern systems, but when it was operational you could receive it basically anywhere on Earth. That is the scale sovereigns play on.
Only people who don’t have the backing of a sovereign state need to go about detecting launches in this circumspect method.
> Some domain specific knowledge was meant to be esoteric
Yes. But this is not that.
> there are a variety of better licenses such as CC-non-commercial that allow peaceful uses of the code without allowing it to be used by literally anyone on the planet
Are you kidding me? :) In the top of your comment you worry, wrongly, about Kim and Putin using the given code. And your suggested solution is to release it under a different licence? :) You think they would care about that?
========
It is widely recognized that rocket launches can be an anthropogenic source to trigger traveling ionospheric disturbances (TIDs) by generating acoustic-gravity waves (Afraimovich et al., 2002; Arendt, 1971; Bowling et al., 2013; Calais & Minster, 1996; Chou et al., 2018; Ding et al., 2014; Kakinami et al., 2013; Li et al., 1994; Lin et al., 2014; Lin, Chen, et al., 2017; Lin, Shen, et al., 2017; Noble, 1990). The rocket-induced long-distance propagating TIDs associated with shock/ducted gravity waves and internal gravity waves were observed by using Arecibo incoherent scatter radar (Noble, 1990) and ground-based Global Positioning System total electron content (TEC) observations (Calais & Minster, 1996). Lin, Shen, et al. (2017) first reported the rocket-induced shock waves and concentric TIDs (CTIDs) subsequently using Global Positioning System TEC over California-Pacific region. They suggested that the CTIDs are the manifestation of concentric gravity waves that were originated from the mesopause region.
====
The effect seems to be proven quite a while ago. Using GPS receivers to make that widely accessible seems to be new, but I honestly doubt that military intelligence would rely on that - I’m confident they have more direct methods to detect launches such as (radar) satellites.
Ham radio is actually where you’ll find a lot on the subject. “Band conditions” are determined by the amount of ionospheric disturbance present. For example, meteors entering the atmosphere produce a disturbance that can reflect radio—there are ham radio techniques that exploit this to communicate.
https://gcn.gsfc.nasa.gov/gcn3/32744.gcn3 ("GRB221009A: Detection as sudden ionospheric disturbances (SID)")
https://www.qsl.net/df3lp/grb221009/KLM_grb221009a_magnitude... (from the above link)
http://abelian.org/vlf/grb221009a-DHO.png
http://abelian.org/vlf/grb221009a-NAA.png
http://abelian.org/vlf/grb221009a-NSY.png
[0] https://news.ycombinator.com/item?id=33215572 ("Record-breaking gamma-ray burst possibly most powerful explosion ever recorded")
This was detected with VLF radio, but I wonder if this kind of event also has an effect on GPS signals? The time-of-arrival of astrophysical gamma rays isn't uniform across the earth.