더불어 민주당

THAAD: Technical Myths. To Hit the Warhead, You Need to Find It First. Can THAAD Do That?

“In preparing for battle, I have always found that plans are useless but planning is indispensable.” ? Dwight D. Eisenhower

Controversy on the THAAD missile system is revealing a further inconvenient truth and, at the same time, it is providing our society with important lessons. The THAAD missile system should have been discussed, investigated, tested, and verified by scientists first; but unfortunately, the mass media and security researchers have jumped into this issue. Thus, our society is now standing at the portals of the structure of ideological discourse of the THAAD missile system.   

To defend ourselves from conventionally armed ballistic missile threats and nuclear threats from North Korea, we need a defense system that actually works. If you are building a national security strategy on the assumption that certain technology is going to work, and it has no chance of doing so, it leads to foreign policy catastrophe, not to mention a massive loss of life.    

Before entering the political controversy of the THAAD missile system, it is essential to address the fundamental technical issues.

President Park’s administration has been stating that the THAAD missile system, with its “sophisticated” technique can defend South Korea against ballistic missile threats from North Korea. However, that claim seems to be based on a technical misperception of the THAAD missile system.

It’s a no-brainer that to hit the warhead, finding the warhead should be first and foremost. According to Professor Postol, Professor Emeritus of Science, Technology, and International Security at the Massachusetts Institute of Technology, the use of infrared homing on the THAAD interceptor makes it extremely vulnerable to decoys, even when the THADD radar can measure decoy range separation during atmospheric reentry. This is because the infrared sensor has no ability to determine the distance to targets and the radar has no ability to determine the exact azimuth of each target if they are only roughly 100 meters so off the reentry trajectory of the warhead. As a result, the information about range-to-target is of no use to the THAAD interceptor for purposes of vision.

Imagine we were standing under the stars and someone says that the third-nearest star to Earth is the one he is referring to. When you search the sky with your eyes, you see many stars, but you have no idea which star is the third-nearest from the Earth.

The reason for this is simple: Some stars are dimmer and others are brighter, and this has little to do with their distance from the Earth. So, all your eyes can determine is that there is a bright object at a certain location in the sky (azimuth and elevation), but you have no way of knowing why the object is brighter or dimmer. As it can be brighter or dimmer for reasons other than its distance from the Earth, you cannot determine the distance of the star with your eyes alone.

This is why THAAD is deeply vulnerable to simple decoy countermeasures. In other words, it is very hard for the THAAD interceptor to tell the real object - the warhead - from decoys.

Professor Postol pointed out another major drawback of THAAD that was the maneuvering of targets, which is a serious issue for defense. For interceptors to be adequate, they must have a greater ability to accelerate laterally then the target they are trying to hit. This requires that the interceptors have tremendous agility - the ability to move laterally with a minimum of delay - and great acceleration - the ability to achieve very high lateral accelerations very quickly.

Imagine you are an American football player, and you are trying to tackle another player who is running down the carrying the football. If the football-carrier takes a lateral step to get around you, you can also take the same lateral step instantly in order to tackle him.

However, in reality, you may not know exactly which way the runner is going to maneuver. The runner may have very good deceptive moves that make it hard to determine which way they are about to run.

So when the runner maneuvers, you can also maneuver, but you may not be able to maneuver instantaneously. As a result, the only way you can “intercept” the runner is to accelerate more rapidly than the runner did so you can “catch up” to his lateral maneuver.

This means that if you are the interceptor, you must be able to outmaneuver - in terms of lateral acceleration - your target. The longer it takes you to determine the direction you must go to catch the maneuvering target, the more lateral acceleration you need. You need to respond very quickly, be very agile, and you achieve a high acceleration very quickly. That’s why the need for an agile high-acceleration interceptor is so important.

In spite of all technical defects that point out the uselessness of the THAAD missile system, none of these issues have been publicized or put under the spotlight.

Professor Postol said, “it seems to be inescapable that the THAAD radar will not be controlled by South Korea; it will be operated by the Americans, and they are very likely to operate it as they see fit.” Additionally, he stated that “it is doubtful that the U.S. can be trusted to tell us the truth, at least on this.”

Experts say it is very unfortunate that we’ve been treated in this way as an ally of the U.S., but the bigger misfortune is that President Park’s administration has never told us the technical truth about the THAAD missile system. They also articulate that it is also possible that, if someone has incentives for the THAAD missile system to deploy, he or she has given President Park faulty information. If President Park has been misinformed about the THAAD missile system, she should find out who told her what, and hold them accountable.

Democratic Party of Korea (DPK) is planning to continue to hold series of discussions and hearings about the THAAD missile system from now on.

October 5, 2016

Democratic Party of Korea (DPK)

사드: 기술적 미신 (근거없는 믿음). 탄두를 요격 하려면, 우선 탄두를 찾아야. 사드로 가능한가 (사드가 탄두를 찾을 수 있는가)?

“전쟁은 미리 세워놓은 계획은 대부분 소용이 없지만, 계획을 세우는 것은 반드시 필요하다.” 아이젠하워.

사드를 둘러 싼 논의는 우리 사회에 불편한 진실과 동시에 중요한 교훈을 던져주었다. 사드 문제는 우선 과학자들에 의해서 토론, 조사, 시험, 그리고 입증 되었어야 함에도 불구하고, 불행하게도 언론과 안보학자들이 먼저 끼어들었다. 그래서, 현재 우리 사회는 사드에 대한 이념적 담론 구조의 입구에 서 있다.

북한의 미사일과 핵 위협으로부터 한국을 보호하기 위해서는, 실제로 작동하는 방어시스템이 필요하다. 만약 국가의 안보 전략을 어떤 특정 기술이 작동할 것이라는 가정 하에서 짰는데, 그 기술의 실행이 전혀 불가능한 것이었다면, 이는 외교 재앙은 물론, 대량 사상으로 이어질 것이 뻔하다.

사드를 둘러싸고 정치적 논란으로 들어가기 전에, 기본적인 기술적 문제를 짚고 넘어가는 것이 필요하다.

박근혜 정부는 사드가 “정교한” 기술이 있으므로, 대한민국을 북한의 미사일 위협으로부터 지켜준다고 했으나, 그 주장은 사드에 관한 기술적인 오해에서 출발한 주장인 것 같다.

탄두를 때리기 위해서는 우선 탄두를 발견하는 것이 선행되어야 한다는 것은 누구나 알 것이다. 포스톨 MIT 명예 교수에 의하면, 적외선 유도장치는 기만탄에 극도로 취약하며, 이것은 탄두의 대기권 재진입 시 사드 레이더가 기만탄의 거리 차이를 측정할 수 있더라도 마찬가지이다. 적외선 센서는 표적과의 거리를 파악하지 못하며, 레이더는 기만탄들이 탄두의 재진입 궤적보다 100 미터 정도만 떨어져도 각 표적의 정확한 방위각을 파악할 수가 없다. 따라서, 표적과 거리에 대한 정보는 시각적인 측면에서 사드 요격 미사일에 아무런 쓸모가 없다.

우리가 별들을 바라보고 있는데, 누군가가 지구에서 3번째로 가까운 별이라며 어던 별을 가리켰다고 가정해 보자. 수 많은 별들이 보이는데, 어느 별이 지구에서 3번째로 가까운지는 눈으로 분간할 수가 없다.

이유는 간단하다: 어떤 별은 어둡게 보이고, 어떤 별은 더 밝게 보이는데, 이 밝기는 별과 지구 사이의 실제 거리와는 상관이 없다. 우리가 눈으로 보고 판단할 수 있는 것은, 밤 하늘 어딘가에 밝은 물체가 있다는 것일 뿐, 어느 것이 실제로 더 밝은지 어두운지는 알 방법이 없다. 이것이 밝거나 어둡게 보이는 것이 지구와의 거리가 아닌 다른 이유에서 기인 한다면, 눈으로 별의 밝기를 봐서는 별과 지구 사이의 거리를 알 수가 없다.

포스톨 교수는 사드의 또 다른 큰 단점으로 기동성 (maneuver)을 지적하였다. 방어에 있어 기동성은 매우 중요한 문제이다. 요격체는 그것이 때리려는 목표물을 비스듬하게 쫓아가는 상당한 능력이 있어야만 한다. 이것은 요격체에게 엄청난 민첩성과 속도를 요하는 기술이다.

미식 축구 선수라고 상상하고, 공을 들고 뛰고 있는 상대 선수를 넘어트리려 한다고 가정해 보자. 만약에 상대 선수가 사선으로 접근해 온다면, 나 또한 사선 방향으로 즉각적으로 걸음을 바꾸어야 상대 선수를 태클 할 수 있을 것이다.

그러나, 현실적으로는, 상대 선수가 어느 쪽으로 방향을 틀 지, 혹은 고도의 속임수를 써서 어느 방향으로 움직일지 파악하기 쉽지 않다.

따라서, 상대가 maneuver 할 때 (나 또한 똑같이 maneuver 해야 하지만), 나는 즉시 그렇게 하지 못할 수 있다. 그랬을 때, 그 공을 뺏을 수 있는 방법은 상대보다 빠르게 뛰어서 따라 붙는 수 밖에 없다.

즉, 이는 요격체라면 그 요격체가 탸격 하려는 미사일을 outmaneuver 할 수 있어야 하며, 타겟 보다 더 빨라야 한다는 것이다. 어느 방향으로 갈 지 고민하는 시간이 길면 길수록 더 빠른 속도가 필요하다. 매우 빠르게 반응하고, 매우 민첩하게, 또 가속까지 매우 빨라야 한다.

사드를 무용하게 만드는 이 모든 기술적 결함들이 있음에도 불구하고, 이러한 이슈와 진실들은 전혀 공론화 되지 않았다.

포스톨 교수는 사드가 한국의 통제가 아닌, 미국에 의해 가동 될 것 같다, 그리고 미국은 그들이 필요한대로 사드를 작동할 것이라고 밝혔다. 또한, 그는 이 문제에 있어서 미국이 진실을 말한다고 믿을 수 있는지 의구심이 든다고도 말했다.

전문가들은 우리가 동맹국인 미국으로부터 이러한 대접을 받았다는 것은 매우 유감이지만, 더 큰 문제는 박근혜 정부가 단 한 차례도 사드의 기술적 결함에 대한 진실을 알린 적이 없다는 것이라고 밝혔다.

전문가들에 의하면, 누군가 사드 배치로 인해 인센티브를 받을 수 있는 사람들이 박대통령에게 거짓된 정보를 제공했을 가능성도 배제할 수 없다고 했다. 만약 누군가 박근혜 대통령에게 사드에 관한 잘못된 정보를 주었다면, 박 대통령은 누가 무엇을 말했는지를 밝혀내고, 그 사람에게 응당한 책임을 지워야 한다고도 밝혔다.

더불어민주당은 사드 관련 전문가들의 의견청취와 토론을 지금부터 계속 해 나갈 것이다.   

2016년 10월 5일

더불어민주당