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Source: Bulletin of the Atomic Scientists

North Korea’s “not quite” ICBM can’t hit the lower 48 states

Theodore A. Postol, Markus Schiller, Robert Schmucker

 

The dimensions of the Hwasong-14 rocket fired on July 4.

Figure 3.

We have identified this rocket motor as a being derived from a family of Russian rocket motors known as the RD-250 or RD-251. The original motors used six thrust chambers fed by three turbo pumps to together generate roughly about 240 tons (about 530,000 pounds) of lift.


On July 3, 2017, while Americans were preparing for the 241st celebration of the Declaration of Independence, a lone rocket rose from North Korea on a near-vertical trajectory. After five to six minutes of powered flight, the second stage of the missile shut down and coasted to an altitude of about 2,720 kilometers. It then fell back to Earth, reentering the atmosphere above the Sea of Japan some 900 kilometers to the east of where it had launched. The rocket’s upper stage coasted in freefall for about 32 minutes, and the overall time-of-flight, from launch to atmospheric reentry, was about 37 minutes. The launch occurred at 8:39 p.m., United States’ Eastern time. Within hours, the news of the launch was trumpeted by the US mainstream press: North Korea had flown an intercontinental ballistic missile (ICBM), a missile that could carry nuclear warheads to Anchorage, Alaska, and to the continental United States as well!

But the Western press apparently did not know one crucial fact: The rocket carried a reduced payload and, therefore, was able to reach a much higher altitude than would have been possible if it had instead carried the weight associated with the type of first-generation atomic bomb North Korea might possess. Experts quoted by the press apparently assumed that the rocket had carried a payload large enough to simulate the weight of such an atomic bomb, in the process incorrectly assigning a near-ICBM status to a rocket that was in reality far less capable.

Only three and a half weeks later, on July 28, there was a second launch of the same type of missile, this time at night, Korean time. The rocket flew approximately the same powered flight trajectory that it had on July 3 (or July 4 in North Korea), this time, however, reaching a higher altitude—a reported 3,725 kilometers. This longer flight path led to yet more unwarranted conclusions that the continental United States was now directly under threat of nuclear attack by North Korea. Actually, however, in this second case, by our calculations, the second stage of the so-called ICBM carried an even smaller payload and tumbled into the atmosphere at night over the Sea of Japan. The spectacular night-reentry of the rocket—what was almost certainly the heavy front-end of the nearly empty upper stage—created an impressive meteoric display that some experts mistook for the breakup of a failed warhead reentry vehicle.

From the point of view of North Korean political leadership, the general reaction to the July 4 and July 28 launches could not have been better. The world suddenly believed that the North Koreans had an ICBM that could reach the West Coast of the United States and beyond. But calculations we have made—based on detailed study of the type and size of the rocket motors used, the flight times of the stages of the rockets, the propellant likely used, and other technical factors—indicate that these rockets actually carried very small payloads that were nowhere near the weight of a nuclear warhead of the type North Korea could have, or could eventually have. These small payloads allowed the rockets to be lofted to far higher altitudes than they would have if loaded with a much-heavier warhead, creating the impression that North Korea was on the cusp of achieving ICBM capability.

In reality, the North Korean rocket fired twice last month—the Hwasong-14—is a “sub-level” ICBM that will not be able to deliver nuclear warheads to the continental United States. Our analysis shows that the current variant of the Hwasong-14 may not even be capable of delivering a first-generation nuclear warhead to Anchorage, Alaska, although such a possibility cannot be categorically ruled out. But even if North Korea is now capable of fabricating a relatively light-weight, “miniaturized” atomic bomb that can survive the extreme reentry environments of long-range rocket delivery, it will, with certainty, not be able to deliver such an atomic bomb to the lower 48 states of the United States with the rocket tested on July 3 and July 28.

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