US Korea Institute

Sunday May 29th 2016
Subscribe to Our RSS feed@38NorthNK on Twitter
38 North offers informed analysis of events in and around the DPRK.

Subscribe for latest



Satellites, Warheads and Rockets: Is North Korea’s Space Program Really about Missile Development?

05 February 2016


This article was originally published on September 28, 2015 but reprinted on February 5, 2016.

When the Soviet Union shocked the world and opened the Space Age on October 4, 1957, it was not a coincidence that its first satellite was launched into orbit on a modified R-7 intercontinental ballistic missile (ICBM). For many observers, that was the message of Sputnik—the rocket that did this, can deliver hydrogen bombs to your cities. Nor was the message sent only once. The first 96 Soviet satellite launches were conducted using modified ICBMs, before Russian engineers bothered to design a rocket specifically for space missions. China still hasn’t bothered to field a space launch vehicle (SLV) that isn’t also a ballistic missile. On the other side of the world, every ICBM design the United States has ever put into service has been adapted to launch satellites at some time or another.

So when North Korea launched its first satellite on December 12, 2012, many observers thought the message was clear: the rocket that did this, can deliver atomic bombs to your cities. And indeed it can. But is this really the purpose of the Unha-3? Is it an ICBM masquerading as an SLV, or an SLV that might someday be repurposed as a missile? There is precedent for both. Or, as Pyongyang claims, is the Unha-3 intended purely for peaceful space exploration?

There are sound technical reasons for using the same rocket in both applications. The fundamental requirement for an ICBM is to accelerate a hydrogen bomb sized payload to roughly 16,000 miles per hour, just above the atmosphere and aimed about 20 degrees above the horizon. To launch a satellite, you want to be a little bit higher, flying horizontally at 18,000 miles per hour. Until your satellites grow larger than your bombs, there is no reason to develop a second rocket, and no way for suspicious outsiders to know for sure what your real goals are.

But if the Unha-3 is intended for use as an ICBM, it’s not a very good one. The second- and third-stage engines don’t have enough thrust to efficiently deliver heavy warheads; a militarized Unha might deliver 800 kilograms of payload to Washington, DC. The North Koreans can probably make a nuclear warhead that small, but it would be a tight fit. With bigger upper-stage engines, which we know the North Koreans have, they could deliver substantially larger payloads. This would allow bigger and more powerful warheads, more decoys to counter US missile defenses, and a generally tougher and more robust system.

The Unha is also too heavy and cumbersome to be survivable in wartime. Too big for any mobile transporter, it can only be launched from fixed sites. Its highly corrosive liquid propellants require hours of pre-launch preparations. That’s a bad combination for North Korea; their fixed launch sites are going to be watched very closely, and particularly in a crisis, any indication that an ICBM is being prepared for launch could trigger a pre-emptive strike.

The same could be said of the old Soviet R-7. As an ICBM, it was pretty much a dud—the USSR never deployed more than 10, and retired them after less than a decade. As a space launch vehicle, its descendants are still in service today.

The North Koreans could press the Unha-3 into limited service as an ICBM, just as the USSR did with the R-7—a temporary measure, until something better is available. They can almost certainly build something better, and they appear to be trying. The KN-08 missile mock-ups, twice paraded through Pyongyang, are exactly the sort of thing a nation like North Korea would build if it wanted to use its eclectic mix of early 1960s rocket technologies to build an ICBM. It is small enough to be mobile and therefore survivable but with the performance (barely) to reach the enemy’s homeland. The Unha-3, by comparison, looks like it was designed to launch satellites rather than warheads.

From a historic perspective, it is worth noting that any ICBM the North Koreans might deploy will owe much to the Unha. ICBMs are necessarily multi-stage rockets, and cleanly separating one stage to ignite another is a surprisingly hard problem. North Korea hasn’t always been able to do this, and finally got it right with the Unha. North Korea does not have any single engine powerful enough to lift an ICBM; the ability to operate multi-engine clusters is also something it learned with the Unha. Earlier missiles used heavy steel tanks and structures; the Unha taught the North Koreans to use lighter aluminum alloys. And its first successful use of high-energy propellants was in the third stage of the Unha. Almost every technology needed to go from crude short-ranged Scud and Nodong missiles to a fully capable ICBM, North Korea learned in the course of developing the Unha.

That’s all history. The key question now, in view of speculation that Pyongyang might launch another rocket, is can the North learn anything more from new Unha-3 launches? Of course, we don’t know if a launch will take place or if it does, whether Pyongyang will use a new and different rocket. But it is still a question worth asking.

If the North Koreans deploy a militarized Unha as an interim ICBM, then every successful flight of that rocket as an SLV will serve to increase the reliability of the ICBM force. Even failed satellite launches would be a learning experience. As the Unha is unlikely to serve as more than an interim ICBM, North Korea may not have time to transfer any valuable lessons from their space launch activities to their ICBM force before the ICBM guys move on to a better missile. But at a minimum, if we see Unha-like missiles sitting in silos presumably aimed at the United States, successful launches of an Unha carrying a satellite would increase the potential threat.

However, it is not clear that these lessons will carry over to any new ICBMs North Korea may try to build. Our current best estimate as is that the KN-08 mobile ICBM, has only the third-stage engine and maybe some guidance hardware in common with the Unha (figure 1). Everything else will be similar in concept but different in execution, and the execution is the part that matters. Remember that the legendary ’57 Chevy Bel Air was built by the same people who came out with the “unsafe at any speed” Corvair three years later. No matter how reliable the 2015 Unha turns out to be, the 2020 KN-08 will be an entirely different beast.

Figure 1. Comparison of the Unha-3 and KN-08 (Estimated)

(Image: John Schilling/38 North)

(Image: John Schilling/38 North)

What if North Korea does launch an even larger rocket than the Unha in October? That may be its game-plan given construction activities over the past few years modifying the gantry to handle a bigger rocket. What may be good news for North Korea on the satellite launch front—a larger rocket would be more useful for launching satellites—would probably not be useful in helping the North build smaller, mobile ICBMs. The Unha, as noted, is already too big and clumsy to be survivable in wartime.

Still, there is one area where satellite launches might make a major contribution to North Korea’s ICBM program. An ICBM warhead, unlike a satellite, needs to come down as well as go up. North Korea has never demonstrated the ability to build a reentry vehicle that can survive at even half the speed an ICBM would require. If and when they do, what is presently a theoretical threat will become very real and alarming. An SLV gives the North the opportunity to test a reentry vehicle without admitting it is part of a missile.

This could be done by launching the reentry vehicle into Earth’s orbit, perhaps carrying a scientific payload where a missile warhead would go, and bringing it back down in a controlled fashion. Or it could be done by putting the reentry vehicle under an enlarged payload shroud, then “accidentally” cutting the third-stage burn short. Oops, our science experiment accidentally fell into the South Pacific at fifteen thousand miles an hour. If anyone is paying attention, the fact that a North Korean ship was parked near the impact zone receiving data on the flight’s performance and plucking the remains from the sea will be a dead giveaway.

So we have two warning signs to look for from the North Korean space program. First, using Unha rockets to launch satellites at the same time they are deploying Unha-derived missiles in hardened silos. That might indicate that North Korea is planning to keep an Unha-based ICBM in service long enough to invest in improving its reliability. Second, conducting high-speed reentry vehicle tests during satellite launches. The data from those tests would carry over into any long-range missile program. But it’s not something they can really keep a secret.

Outside of those two areas, if North Korea says its program is for launching satellites, they are probably launching satellites. The usefulness of such launches in terms of developing better ballistic missiles is extremely limited. Of course, we will want to know what kind of satellites; there are certainly possible military dimensions to a North Korean space program. But that’s a question for another day.

Reader Feedback

7 Responses to “Satellites, Warheads and Rockets: Is North Korea’s Space Program Really about Missile Development?”

  1. Vahe Demirjian says:

    Dear Mr. Schilling,

    You had speculated from satellite imagery that North Korea might use its newly extended launch tower to launch rockets bigger than the Unha-2 or Unha-3, namely a launcher the size of the Ariane 4. However, the Unha-4 SLV used to launch Kwangmyongsong-4 is exactly the same height as the Unha SLVs used in the 2009 and 2012 space launches (compare KCTV footage of Kwangmyongsong-4 launcher with Kwangmyongsong 3 launcher; and The German space expert Norbert Brugge cautions that the DPRK doesn’t yet have the know-how to make new large engines for an Ariane 4-type SLV (, and the planned Unha-9 (which is probably a bit taller than Unha-2, Unha-3, Unha-4, and yet-to-be-launched Unha-5, Unha-6, Unha-7, and Unha-8) is reportedly intended to carry a lunar spacecraft (see

    That said, a North Korean SLV the size of Ariane 4 and other launch platforms for geostationary satellites is not yet on the horizon, even though a GTO satellite is in North Korea’s blueprint for space exploration.

  2. keve says:

    J_kies, yes Safir was liquid fuel rocket. Iran Sejjil was solid fuel rocket which was NOT used for satellite launch that resembles NoKor Musudan Missile. Record shows Iran have similar missile capability later, once NoKor fields newer missiles and satellite rockets. But this does not mean KN-08 missile is solid fuel as storage-able liquid fuel has greater advantages in thrust and control. Again, lacking evidence, should not be implied that missiles does not exist, but reasonable assumption is better than nothing.

    But US or allies “lacking evidence”, due to limited intelligent reports, of KN-08 credibility does not mean that KN-08 does not exist. Also from statements from US Military Generals and Admirals, with access to classified informed, conclude that KN-08 does exist in NoKor.

    Russian, USA, and any other nation that provide public view of their missiles are of mockups of real representation, and NoKor is no exceptions. Perhaps low quality pictures and assumptions are misleading the public.

  3. J_kies says:

    Keve since the physical evidence we have for the KN-08 is some parade photos of really bad mockups (and some highly speculative looks at commercial satellite photos), we have no hard evidence that the KN-08 exists at all. That said; much of the visible detail is more suggestive of a liquid fuel design.

    The DPRK has only the KN-02 (a SS-21 clone) as a solid fueled missile.

    The Iranian micro/nano satellite launcher is the SAFIR a two stage liquid fueled system based on SS-4 like technology in the first stage and SS-N-6 like vernier thrusters in the second stage. The Iranian MRBM solid is the Ashura (2000-2400 km ground range and has never been claimed for use as a space launcher.

  4. keve says:

    What evidence is there to show KN-08 ICBM is not solid fuel? With Iran importing much of their missile technology and science exchanges with NoKor, likely NoKor is fielding solid fuel ICBM, because Iran sent satellite into low orbit with solid fuel rocket about 8 years ago, which resembles that of NoKor Musudan (IRBM) missile except the external mounted mini-rocket nozzle for lift off stability.

  5. John Schilling says:


    My current best estimate for the Unha 3rd stage plus payload assembly is right at 3.8 tons, so that matches. The problem for a two-stage Unha as an ICBM is that the second stage has fairly low thrust, probably a single modified Scud engine. That works reasonably well for a direct-ascent satellite launch without an in-flight restart, but it leads to excessive gravity losses on a lofted ICBM trajectory. However I model it, I can’t get a militarily useful payload to the US east coast with a two-stage Unha.

    Performance to the west coast is fairly robust, better than a thousand kilograms, but I don’t see the North Koreans building an ICBM that can’t hit e.g. Washington DC if they have any choice in the matter. And they did have the choice of adding a second Scud engine, if that’s what they wanted. Still could have orbited a small satellite to pretend the initial flights were space launch tests.

    So that’s another dimension we can look at. If they fly Unhas with low-thrust second stages like they have been, they probably aren’t pretending – they really want to launch satellites. But if they switch to a high-thrust second stage, now I’d want to look extra hard for a cluster of Unha-sized silos because that would look like they were testing a missile.

  6. XuTianran says:

    Dear Mr. Schilling,

    Great article! but allow me to have some different opinions: if KN08 is mobile, it probably cannot use NTO/UDMH based engines such as the R-27. No land mobile/movable system ever used NTO so I guess KN08 would not be the exception, otherwise it would face serious deployment restrictions. China tried hard to develop the DF14/22 mobile ICBM and the best they can get is using the AK-40 oxidizer.

    If the North Koreans do have some smuggled R-27s, why not use them as the second stage of the Unha-3 ICBM? Would offer much heavier throw weight than the KN08 configuration mentioned in your article. And Unha-3’s size is fine for silo deployment.

    In case that KN08 is indeed a land mobile missile that can reach the US mainland, i guess it would use AK-27/40 oxidizer and UDMH as fuel. They might have been testing it for the last three years.

    Best regards

  7. J_kies says:

    Dr Schilling; as usual your open source work is well considered and thought provoking. However; certain issues arise in the interpretation of the 12/12/2012 launch video and the demonstrated energetics of the Unha-3 stack. First; the effective size of the Unha tanks may be underestimated as the launch video appears to show the engine cluster extending past the visible missile walls. Dimensions of the recovered Unha hardware should be applied to refine estimates. Second; the advertised NOTAM ‘splashing’ the second stage off Luzon constrains or empowers the energetics estimate depending on the masses you assess for the fueled 3rd stage, hardware and payload. With the advertised burn timeline on the 3rd stage and the Soviet literature on Zydb vernier fuel consumption rate; reasonable total mass estimates pushed to the Luzon splash point (if the 3rd stage had not fired in the plane-change and orbit insertion burn) range from 3.8 to 5 tons. In the event that a military payload was placed onto the second stage and fired on an ICBM loft profile; the demonstrated 2 stage kinematic capability is a very reasonable ICBM.

Leave a Reply

Credit for photo of young North Korean girl: T.M. All rights reserved, used with permission.