To measure the prowess of North Korean missiles, researchers spy with open-source clues
Judy Woodruff: Over the last two weeks, Miles O'Brien has taken us on a tour of what's publicly known about North Korea's nuclear weapons program.
In the third and final part of his series, Miles looks at how those bombs might be delivered.
Tonight, on the Leading Edge of science, the sleuths searching through open-source clues to North Korea's fast-developing missile program.
Miles O'Brien: North Korean missiles are flying much farther and much more frequently since Kim Jong-un became supreme leader in 2011.
He has reigned over more than 80 launches so far. The outside world watches warily with a network of early warning radar, sensors and satellites that track the missiles in real time to be sure they are indeed tests.
Once the basic data is released by NORAD, the sleuthing work begins for people like Jeffrey Lewis.
Jeffrey Lewis: We looked at open-source data sets of surface-to-air missile sites.
We can usually add quite a bit of detail because we can model the missile and we can usually find the precise launch location using photographs.
Miles O'Brien: Lewis is director of the East Asian Nonproliferation Program at the Middlebury Institute of International Studies at Monterey.
He and his team look long and hard at the images released by the regime.
Jeffrey Lewis: Every time the North Koreans conduct a missile launch, we try to figure out where it happened. We take all the pictures that they released and we try to what we call geolocate them. We're able to see where the launch occurred, and we are even able to tell where Kim Jong-un was standing when he watched it.
Miles O'Brien: Lewis and his team are dialed into a global network of armchair analysts on a similar mission.
Marco Langbroek is a longtime amateur satellite tracker and blogger based in the Netherlands.
Marco Langbroek: The end result of all these measurements is that you have a very nice calibration of what directions is where on the horizon.
Miles O'Brien: He gave me a fascinating glimpse into a realm that sounds like an oxymoron, open-source spying.
The North Koreans released these images of their last and largest missile test of a Hwasong-15 in November of 2017. Langbroek spent a lot of time charting the stars in these images.
Marco Langbroek: We can build a timeline of events in the moment this truck arrives, starts to erect its missile and up to launch.
Miles O'Brien: Based on this, Langbroek estimates it took two hours for the North Koreans to launch the Hwasong-15. Langbroek knows the location of those buildings thanks to Lewis and his team.
It all began with a 13-second video showing Kim Jong-un's father and predecessor, Kim Jong Il, in a building with some Nodong missiles in the early 2000s.
Jeffrey Lewis: It has these very unusual windows along the back and the side and in the roof. And we thought, if we know where the windows are, then we can model the inside of the building, use that to model the outside of the building. And then, if we know approximately where to look, we can find this thing in a satellite photograph.
Miles O'Brien: They made a 3-D model of the building and the missile-carrying truck based on the images, and homed in on their quarry.
Jeffrey Lewis: And so there it is. You can see it's exactly the building that we imagined. And you can see the reason that they added the big skylight was precisely so that the vehicle would fit in and that they could lift the missile all the way up.
Miles O'Brien: Similar techniques can also give outsiders an inkling on how successful a missile test is.
Marco Langbroek: What you want to do is somehow correct for this distortion.
Miles O'Brien: Langbroek found this image of Kim Jong-un very telling. The map evidently shows the intended trajectory of the missile.
Marco Langbroek: You can compare whether what they meant to do with their launch actually matches what the rocket really did.
Miles O'Brien: He uses software that corrects the distortions caused by the perspective of the camera. He compares the red line on the map with trajectories of the tests released by Western military sources.
Doing all of this tells you pretty much they had a successful test, I guess, right?
Marco Langbroek: Yes. And what it basically shows that if they do the best, they can actually aim their missiles quite well, which, of course, important in a real war situation.
Miles O'Brien: So far, the North Koreans have tested their large missiles on highly elliptical suborbital flights. Flatten out the arc and a Hwasong-15 can reach any location in the continental U.S.
Jeffrey Lewis: This is a model of the Hwasong-12. This is the missile that was being lifted by the crane.
Miles O'Brien: Lewis also measures the prowess of North Korean missiles by timing their acceleration off the launch pad.
Jeffrey Lewis: If you know how heavy the thing is and how quickly it is being pushed, you know how much power is being used to push it. So, we have been able to estimate the strength of the North Korean engines and, as it turns out, we get exactly the same number as the leaked U.S. intelligence community estimate.
Miles O'Brien: They sussed out its weight by looking at these images of Kim Jong-un watching launch preps for a Hwasong-12. The key? A logo of a Japanese company on the crane.
Jeffrey Lewis: And so by modeling the building and the missile and the crane, we were able to figure out how far the arm was extended, the angle that the arm was at. And then we could look at the specifications for this particular commercial crane and figure out approximately how much the missile weighed.
When we did the crane analysis, one of the things we discovered is that North Korea's missiles were more advanced than we thought, that the missile itself was still very strong, but much lighter than we expected.
Miles O'Brien: Lewis believes the North Koreans have the technology and knowledge to mill so called isogrid pieces like this. They are as strong as a solid piece of metal, but much lighter.
Jeffrey Lewis: This is hard to do unless you have modern computer, numerically controlled machine tools, and that's precisely what Kim Jong-un was showing us in that building, was that they have the capability to do this sort of thing.
Miles O'Brien: But they also have the capability to doctor images.
Lewis discovered Kim Jong-un's ears are often Photoshopped. And remember that star field Marco Langbroek analyzed? A later image from the same vantage point of the launch itself shows stars that would be behind the camera.
Marco Langbroek: The star backgrounds are dramatically different, because here it shows Orion, and here it shows a part of Andromeda with Andromeda Galaxy over here, and these are completely different parts of the sky. This is in the south-southwest, and this actually in the northwest.
So, that's not possible. They should show the sky background, but they don't.
Miles O'Brien: What would be the reasons to do that?
Marco Langbroek: I think it's simply for aesthetics. They wanted very nice propaganda pictures. And, of course, what's more beautiful as propaganda than having your ICBM soar into a star-spangled sky? It's aesthetics.
Miles O'Brien: But you have to wonder why they tip their hand as much as they do?
Jeffrey Lewis: If I were the North Koreans one thing I might do is just stop all of this propaganda altogether. But then they lose the deterrent value, right? They lose the threat, because, if you can't see it, then you don't know it's real.
So, I think we're both locked in this game where they want to tell us some things and not others, and our job is to figure out what those other things they don't want to tell us are.
Miles O'Brien: Until technology made all this possible, this job fell in the realm the professional spies, shared only with policy-makers that have a security clearances.
Siegfried Hecker: This was actually my very first trip.
Miles O'Brien: Nuclear physicist Sig Hecker is one of those people. He ran the Los Alamos National Laboratory from 1986 through 1997. He supports the open-source sleuthing.
Siegfried Hecker: The open-source informs the public. And what's actually important, of course, when you do open-source, you do get more eyes on the problem, more people to think about it, more people who think in ways that perhaps and North Koreans might think that than what we have in our government.
Miles O'Brien: In fact, Marco Langbroek says his Web site is routinely visited by the CIA, and Jeffrey Lewis and his team get invitations to brief government analysts.
So what is the takeaway for the concerned public? Even though North Korea has not proven it has a weapon small and robust enough to survive the fiery reentry into the atmosphere, it can launch a missile with enough payload to carry a bomb to any American city.
For the PBS NewsHour, I'm Miles O'Brien.
Judy Woodruff: You can watch all three of Miles O'Brien's reports on North Korea's nuclear capabilities online at PBS.org/NewsHour.