A speculative drawing of what the North Korean rocket design might be.Credit: C. Vick/globalsecurity.org

Last week's fiery crash of North Korea's Taepodong-2 missile has left arms control experts theorizing about what went wrong.

The Taepodong-2 is North Korea's latest missile design. It is believed to be capable of reaching Alaska or the western United States and has been a source of anxiety for US officials who claimed that, if necessary, they would use their own missile defence system to down a test flight.

But that turned out to be unnecessary. Just 42 seconds after its 4 July launch, the missile plunged into the Sea of Japan, according to US, South Korean and Japanese intelligence. Much of what is known about the failed launch remains shrouded in secrecy, but the length of the flight indicates that the rocket's massive first stage fired correctly and that the guidance systems were initially operational, according to Jonathan McDowell, an expert on space launches who works at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts. "It's very hard to get this far," he says.

The failure appeared to take place at the moment rocket designers call 'maximum q', when a rocket feels the greatest aerodynamic forces.

Bumpy ride

The first stage had probably not finished firing by the time of the crash, says Charles Vick, a senior analyst with globalsecurity.org, a non-profit defence analysis group based in Alexandria, Virginia. But he suspects the fault lay elsewhere.

Vick says he has seen reports that something fell from the rocket immediately after take-off. He thinks that part of the final, third stage may have pulled loose when under maximum strain, and struck the body of the rocket. "Something came crashing down, and that's when all hell broke loose," Vick hypothesizes. After that, "it was a wild ride."

That 'something' may have been a shroud covering a small satellite that the North Koreans intended to put into orbit, Vick says. Such a problem would be relatively easy to fix, he notes. "If the shroud is the problem, we could see another flight within a year or less."

Simple glitch

But other types of failure are just as likely, says McDowell. For example, the steering mechanisms might not have been strong enough to guide the rocket at maximum q, or a software or guidance glitch might have caused the crash. If the latter were true, he says: "They could fly it again in a few months."

McDowell adds that regardless of the specifics of the failure, the 42-second flight shows that the North Koreans are indeed skilled at rocketry. Most launch failures occur within the first few seconds after lift-off, he says. During the early days of the US programme, says McDowell, a 40-second flight would have been described as a 'partial success'.

Visit our abuzzovernorthkorea.html">newsblog to read and post comments about this story.  

GlobalSecurity.org