North Korea’s Teapodong-2 Unha Missile Launch: What might we learn?

Indications are that North Korea is moving ahead with its planned launch of a missile with the intent of placing a satellite into orbit. The North Koreans are portraying the launch in purely innocuous, civilian terms even naming the rocket “Unha,” which means “Milky Way” in Korean, to emphasize its space-oriented function. In the West, the rocket is called the Taepodong-2 and is thought to be a long-range (but not truly intercontinental range) ballistic missile.

Even if the rocket launches a satellite, and recent news reports say the payload sections seems to be shaped and sized for a satellite, it would be an important step in their military ballistic missile program. In the early days of the Soviet and American space programs, there was little distinction between military and civilian rocket development and the same would be true of North Korea’s upcoming launch. What I want to discuss in this essay is the question of how much can the outside world learn if the North Korean test goes through, what does it tell us about their ballistic missile capability?

According to the North Korean statements, the Kwangmyongsong-2, or Bright Star Light, satellite is a communications satellite. This is transparently nonsensical, of course. Most communication satellites are in geosynchronous orbit, far beyond the reach of the North Koreans. A single satellite in low Earth orbit will not be a useful communications satellite and I do not believe anyone is expecting the North Koreans to launch a whole constellation of satellites. Perhaps what they mean by a “communications satellite” is that the satellite will be communicating to us, not being used by people to communicate among themselves. According to North Korea, their last satellite, launched in August 1998, orbited the Earth continuously broadcasting the “immortal revolutionary” tune, “Song of General Kim Jung Il.” (This is consistent with the name, Kwangmyongsong or Bright Star Light or Bright Lode Star, is one of the innumerable sobriquets of Kim Jung Il.) Such a satellite never existed in fact. All reports from outside North Korea state that the last stage of the rocket exploded, destroying the satellite. United States Space Command has never tracked any object that could be the North Korean satellite and has detected no such transmission from space. (There is a musical precedent: The first Chinese satellite, which had the notable distinction of actually going into orbit, transmitted the tune, “The East Is Red.”)

The 1998 launch used a Taepodong-1 missile as the space launch vehicle (SLV). The Taepodong-1 is made up of a Nodong missile as a first stage with a Hwasong-6 missile as a second stage. (We should keep in mind that some North Korean missiles, such as the Nodong and Hwasong-6, have been produced in number and even exported so they are well characterized. The Taepodongs are different, they have never been successfully test flow and they are put together from other components. I am somewhat uncomfortable assigning them names as though they are production missiles; at this stage, each one might me a one-off. We shall see.) In the 1998 flight, a third stage was added to boost the small satellite into orbit. It was this additional third stage that apparently failed so the North Koreas could have got substantial and important data on the performance of the first two stages that would have made up the two stages of a military ballistic missile.

The Taepodong-2 was tested only once in 2006 and exploded about 40 seconds into its flight and it seems this upcoming launch is a retry of that failed test. The first stage of the Taepodong-2 appears similar to the Chinese CSS-2 missile. David Wright speculates that the first stage will have four Nodong engines operating together. A single Nodong serves as the second stage. The North Koreans have declared warning zones where the first and second stages are expected to impact. David Wright and Geoffrey Forden have worked backward from the announced splash down zones to see whether they are consistent with the presumed configuration of the Taepodong-2 and they check out.

It would be better for the world if the North Koreans did not go through with this test (perhaps the best outcome would be for the rocket to blow up a few seconds into its flight test—we can always hope) but if they conduct the test, the rest of the world might as well learn as much as we can from it and we can learn a lot.
The missile is being launched from the sort of launch pad that one would expect for a SLV. It is being assembled out in the open and the North Koreans are making no effort to hide the missile. The press has released some low resolution images but the United States, and others, have photo-satellites that can take much higher resolution images, perhaps seeing detail down to several centimeters. It is conceivable that the United States and perhaps others are bold enough to fly unmanned drones nearby to take even more detailed photographs. But unless a drone gets shot down, do not expect any public announcement from either side. So while we on the outside speculate about what the size and shape of the missile is, national intelligence services already know that before the missile even flies.

The missile will be tracked by radar—the Americans and Japanese have radar ships in the area and South Korean and Japanese will have ground-based radar—and this will provide a detailed, instant-by-instant record of the trajectory of the missile. That allows a calculation of the acceleration, which, in turn, allows us to calculate the ratio of the thrust to the weight of the rocket. If we knew one of those, we could then calculate the other and we will get to ways to determine the weight.

The rocket will accelerate and the rate of acceleration will increase because the thrust of the engines remains constant (some more advanced rockets do fancy things with throttling their engines but the North Koreans are probably not there yet) but the rocket is always getting lighter because it is burning up fuel all the time. So we do not know the weight of the rocket, or the thrust, or the fuel flow, but we can figure out all the ratios and some unknowns cancel out in the equations. By seeing how fast the acceleration changes, we can figure out one of the most important measures of rocket technology, the specific impulse. Specific impulse is the amount of “impulse” or total push (technically, momentum change) provided by a given amount of fuel. It is measured in newton-seconds/kilogram or, in English units, pound-seconds/pound. (Some American engineers cancel the pounds of force in the numerator and the pounds of mass in the denominator and report specific impulse in units of seconds, which makes any good physicist weep. And trust me, I will get tons of letters explaining how I am totally wrong and don’t understand specific impulse.) The specific impulse depends on the type of fuel, the efficiency of the combustion, and the maximum temperatures and pressures that the rocket engine can stand, all things that are technical challenges, making specific impulse a good measure of overall technical sophistication of a rocket builder.

Keep in mind that, for long-range rockets, the initial weight of the fuel is about 90% of the total weight, the structure—the tanks, engines, and so forth—are most of the remaining 10% and only a couple of percent of the total weight is payload. So when the rocket first takes off, the fuel is mostly lifting itself. So the efficiency of converting the fuel into thrust is critical; small changes in efficiency translate into large changes in payload that can be delivered to great distances.

As the first two stages separate, they will fall back to Earth. Radar will be able to track their trajectories as well and measure how they are decelerated by falling through the atmosphere. If we knew the drag coefficient of the stage, then, in principle, we could figure out the weight of the empty stage. The problem is that the stages will be tumbling in some complex way as they go down. Even so, by measuring the radar cross section at each instant, particularly at a variety of radar frequencies, and comparing measurements from more than one radar, a computer could develop a picture of how the stage tumbles and then calculate the air resistance and, from that, the weight of the empty stage. I do not know whether the accuracy is great enough to add to information that we would have from other sources, for example, based on knowledge of the Chinese CSS-2 missile. When the stage breaks up in the atmosphere, all bets are off but the first stage at least might hit the water intact. That raises the interesting possibility that pieces could be recovered but the predicted impact area is over very deep water.

Based on past North Korean practice, we know the general category of propellant the rocket uses but not the precise type. The oxidizer will be nitrogen tetroxide or nitric acid or some mixture of the two. The fuel could be kerosene or something more energetic, like dimethyl hydrazine. The two stages could use different propellants. I wondered whether, by observing the plume from the rocket, perhaps from space, and analysis of the spectra, it would be possible to determine the type of propellant. I discussed the idea with a couple of people and the consensus is that you could identify atomic species but not ratios. So the spectrum would reveal nitrogen, but not enough information to know that it came from nitric acid or hydrazine. In fact, the specific impulse will be a better indicator of the propellant type.

Remember that radar tracking gives us ratios, of weight to thrust, for example. If we had one, we could calculate the other but we cannot calculate payload mass directly. If this were a ballistic missile test, then the weight of the reentry vehicle could be determined by watching how it decelerated in the atmosphere. Then we could make a guess as to whether they could build a nuclear bomb within that size and weight. But this looks to be a satellite launch. Instead of a reentry vehicle, the rocket will have a small third stage that will push a small satellite into orbit. The payload ends up in a ballistic orbit in space where there is no air resistance (or very little). So a one kilogram satellite will follow the same trajectory as a thousand kilogram satellite. That is unfortunate, because if we knew how much the third stage weighed, or how much the rocket could launch into space, then we could calculate how far the rocket could throw a payload of any chosen weight. Because the payload ends up in space, we have to make some guesses about the weight.

Telemetry offers the potential for a great deal of information. By intercepting telemetry, we could get direct information on fuel flows and the like. Since the Taepodong-2 is still being developed—they have never had a successful launch—one would expect the North Koreans to have the rocket heavily instrumented and to transmit all those data back. They might do that but, in past flights, their telemetry has been quite limited.

Could the United States shoot the rocket down? Well, sort of. We do not have the capability to intercept the boosting rocket. But a satellite has to be boosted up to the point where it enters its orbit. (In fact, that is sort of the definition of the “orbit,” the point where the boosting stops and the object goes into an unpowered ballistic trajectory; if it is a ballistic trajectory that doesn’t later intercept the atmosphere, we call it an orbit.) The United States has already demonstrated that it can intercept low altitude satellites; lat year the Navy intercepted an old U.S. spy satellite in a decaying orbit. That was in some ways an easier target because the path could be calculated days in advance. While the North Korean satellite is still under power and being boosted up to orbit, it will not have a perfectly predictable path, making intercept complex but not impossible especially because, based on the predicted first and second stage impact areas, we can make a good guess about the flight path and the Aegis missile could be positioned to make an intercept of the third stage or the satellite before it reached final orbit. Note that this intercept would destroy the satellite, which is a stunt which is just a North Korean stunt anyway, but does not deny any information to the North Koreans about what they presumably really care about, a two-stage ballistic missile with military applications. So, intercept of the third stage might give the U.S. some macho pleasure but would not accomplish any military goal. (It would have political implications that I won’t even try to guess at.)

Does this mean that Aegis would work as an intercontinental ballistic missile defense? No, for several reasons, for example, a ballistic missile does not have to power the reentry vehicle up to orbit, the rockets burn for three to five minutes and the RV is on its way and the trajectory is pointing up rather than horizontally, quickly getting out of range of the Aegis.

Overall, the outside world will gather a lot of information about the Taepodong-2 as a ballistic missile based on this satellite test. We will not know the exact payload and range of the ballistic missile version but will certainly know a great deal more than we do now. Unfortunately, so will the North Koreans. Especially since their test of a nuclear explosive, this is a dangerous development.

12 thoughts on “North Korea’s Teapodong-2 Unha Missile Launch: What might we learn?

  1. ioelrich fails to mention the obvious, that a primitive satellite launch must be hurled due East over the horizon (in order to pick up the rotational spin of the Earth) rather than being shot straight up as is popularly imagined. Without this key fact little else makes sense.

    At the end of Aug 1998 the North Koreans attempted to launch a satellite as part of their country’s 50th anniversary celebration. The rocket was fitted with fail-safe self-destructs in case it got out of control, and carefully launched due East over the sparsely inhabited ocean straits between the islands of Honshu and Hokkaido of Japan.

    Although American spy planes were monitoring the launch, the American government inexplicably says it is caught by surprise, and labels the North Koreans “unpredictable” and “aggressive”. On Aug 31 ’98 the Pentagon tells Americans that the North Koreans have tested an ICBM, aimed eastward at America. This is published as front-page news, and used over and over again to scare the American public. Eventually it leads to over $100B in increased spending at the Pentagon.

    On Sept 15 ’98 the Pentagon quietly reclassifies the rocket as a failed satellite launch. This news is buried in the back of the papers.

    Scientists should let people know that primitive satellites have to be launched due East.

    The current conflict will never be resolved until key facts are brought to light:

    1. Starting July 1952, America launched an extermination program against the North Korean population. Napalm was dropped on civilians, resulting in the deaths of somewhere between 200,000 and 500,000 women and children. It is not necessary to go into how horrifying and disrespectful it is to have your wife or your child treated like a leftover piece of deep-fried chicken, so we won’t go there.

    2. Mr. Kim was 10 years old at this time–old enough to witness this first-hand. The Politbureau members were older. To them, this is personal history.

    3. The current problem solutions are neither military nor political (these have been ineffective). They are in the realm of psychology and counseling. Instead of its best military officers, America should get its best psychologists over to North Korea, and actually listen from first principles to what’s going on. Start with meta-communication.

    4. Transformational healing comes through giving people a clear chance to tell their story and have it be actually heard. Nelson Mandela’s Truth and Reconciliation Commission was effective in bringing about a transformation of South Africa. North Korea’s stories of unfairness have never been seriously listened to. Until America understands and respects where North Korea is coming from, its story will continue to self-perpetuate and metastasize. Lack of trust and understanding on both sides perpetuates the need for hostile positioning, which is wasteful and dangerous. To say that Americans do not understand where North Koreans are coming from is a starting point and an understatement that practically all can agree with.

  2. By definition, a missile is essentially a rocket with a warhead on it. Despite everyone’s certainty of what Kim Jong Il’s ultimate goal is, as currently it is increasingly unlikely that the Unha launch vehicle had a warhead on the top, it would be incorrect to refer to it as a missile.

    I encourage you to reference this with any dictionary of your choosing.

    Captain BBQ is not exactly right but he has identified exactly the problem. A rocket is a device that propells itself by shooting its contents out at high speed. It is a warhead plus guidance that makes it a missile. A missile (and I use the Shorter Oxford English Dictionary) is “A destructive projectile that is self-propelling and directed by remote control or automatically.” So no one every refers to Katyusha “missiles” but to Katyusha rockets because they do have warheads but are unguided. But the question about naming emphasizes why we should be worried about the NK satellite launch. Taking a warhead off and putting a satellite on top may change the name from “missile” to “rocket” but it does not change the thing itself. What the North Koreans tested is what they tested regardless of what we or they call it. A low Earth orbit communications satellite does not wash but what they tested is exactly what they would use as a long-range missile.

  3. My understanding is that North Korea’s guidance systems are still fairly primitive, and lack a secondary sensor to correct accumulated position errors in the inertial guidance system.

    Is that still the case ( if it ever was)?

  4. Ivan Oelrich’s understanding of the capabilities of Aegis Ballistic Missile Defense is as pathetic as the DPRK’s failed attempts at achieving orbit. While he is kind enough to mention the successful intercept of USA-193, he should also mention the 13 for 15 successful Aegis BMD tests that have gone before; not to mention the successful tests of Patriot (PAC-3), THAAD and GMD. Aegis in particular has a remarkably successful record for a complex program at the cutting edge of technology. What is it that Mr. Oelrich demands? 100% success? Or maybe the tests aren’t realistic enough to suit Mr. Oelrich. Mr. Oelrich is a member of the same choir that flatly stated that an exoatmospheric of a ballistic missile RV was impossible when President Regan first proposed Ballistic Missile Defense.

    Mr. Oelrich’s point that the target would move quickly out of range is true if there were only one Aegis ship. The Navy hasn’t practiced BMD in that fashion for 2 years. What Mr. Oelrich fails (or refuses) to realize, is that BMD is a world wide integrated network of sensors and weapons. Nothing will be out of range.

    A wise man is one who knows what it is that he doesn’t know. You Mr. Oelrich, are far from a wise man.


  5. Please insert the word “intercept” into the prior statement to read: “an exoatmospheric intercept of a ballistic missile RV”

    Thank you.

  6. This incident shows the similarities between iranian & N.korean Ballistic missile programs.Few months later , iran test similar missile.In fact we see secret alliance between Iran-N.Korean-Pakistan And China. Iranian role is Paying the cost of programs. N.Korean & chinese role are engineering and manufacturing missiles. Pakistan played as logistic agent.
    I Think Americans are in AMERICAN DREAM.I believe we can see Another Pearl harbor soon.

  7. If you don’t believe this check the similarities between Iranian Shahb 3 – North korean Nodong-1 and Pakistan Ghauri-1 or Iranian Shahab-4 , N.Korean Taepo dong-1 and Pakistan Shaheen-2 or Iranian Shahab-5 , N.Korean Taepo dong-2 ( Missile that tested yesterday) and Pakistan Ghauri-3.
    We can see similarities between Iranian M11 , Chinese Css-7 and Shaheen-1.
    I think the joke of the year is that : Pakistan ( Specially ISI ) is Us Strategic Allied in war with terrorism.

  8. Amir Hossein,

    A little objectivity from you would help. What does Pakistan and ISI have anything to do with this North Korean Missile launch? Please stop looking at everything through your India centric lenses and keep your Indo-Pak obsessions out of these discussions.

    Missile technology is pervasive now. The base technology of Nodong/Taepodong missiles comes from Soviet hardware of the 80s and 90s. This technology has been exported (under MTCR restrictions) to many countries. Blaming everything on the China angle is a disservice to objective analysis of the situation.

  9. Amir hossein is correct when he points out the cross pollination of the Iranian & DPRK space launch efforts. That is, if one were fool enough to accept the DPRK premise that they were engaging in a space launch in the first place.

    It is not too difficult to find in open source, imagery of the Safir (Iranian 2nd stage) and the DPRK TD-2 3rd stage of sufficient resolution to compare their similarities. A useful idiot will accept this as prima fascia evidence of the DPRK’s space launch intentions. It is more likely that the test objective was to correct the problems in the TD-2 1st stage that lead to the 2006 failure. The whole 3rd stage assembly may merely have been a mass to gauge the throw-weight potential of a TD-2 1st stage and Scud C combination, configured to look like the Iranian Safir space launch on 2 February. If the 2nd stage landed within the area the DPRK cordoned of in their pre-launch notice, one must assume that the test results are within the specified margins.


  10. John:
    > Eventually it leads to over $100B in increased spending at the Pentagon.

    You’re right. Personally I think drumming up this hysteria helps the US defence industry.
    Though going by your own Info why would DPRK develop an ICBM. There is only one target for pure revenge. Thats why US is a bit nervous and rightly so.

  11. I’ve read in the past that the Sea Launch version of the Teapodong Missiles I believe it’s designation was the SL-22 or such are modified and have a potential range of 4,200 kilometers or about 2,500 miles..

    These they can fire from submarines and pose a potential threat to America’s West coast..

    Yes their’s are diesel subs antiquated as they might be, it would only take one to go unnoticed to provide a delivery system that would cause a horrific calamity in a populated region such as our West Coast..

    I’m just sayin..

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