Experts Ponder Cause of N.Korean Rocket Failure

North Korea's rocket exploded two minutes and 15 seconds after launch, disintegrated into some 20 fragments and fell into the West Sea. The North unusually admitted the failure. Rocket experts attribute it to a problem with the first-stage booster, failed separation of boosters or a rushed launch schedule.

◆ Booster Problems

The first-stage booster exploded into about 20 fragments scattered over waters west of Taean far away from the point west of the Byeonsan Peninsula where the regime had predicted they would land.

About 56 percent of launch failures are caused by a problem with the first stage. The explosion is believed to have been caused by a fuel leak from a propellant engine or a turbopump malfunction rather than booster separation. Yoon Woong-sup, a professor of mechanical engineering at Yonsei University, said, "If a problem occurs during the booster separation process, there is low possibility that the first-stage booster will explode because its fuel is already spent."

But Cho Kwang-rae, the head of the Korea Aerospace Research Institute's satellite launch project, said, "Nobody can rule out that a problem occurred during the separation of the first-stage booster."

Considering that another rocket failed to place a satellite into orbit due to insufficient liftoff thrust in 2009, the North may have overcompensated and increased the engine's liftoff thrust too much this time. Or the rocket may have been exploded by remote control, or an automatic explosion trigger was activated when the rocket veered off course, other experts speculate.

◆ Rushed Launch

Still others speculate that the accident occurred because the North rushed the launch to coincide with the centenary of nation founder Kim Il-sung. It is unclear why the regime launched the rocket from a fog-shrouded launch pad on Friday morning, a day earlier than experts had predicted.

"Given the insufficient preparations at the Tongchang-ri launch pad, we got the impression that the North was in a hurry," a South Korean government official said. "The regime may have been negligent in the final checkup" because other pressing centenary events lay ahead over the coming days.

◆ No Progress

In April 2009, the rocket failed to enter orbit, but the second- and third-stage boosters separated successfully. But this time, even the first-stage booster failed to separate and exploded in midair. The North has so far failed four times to launch long-range missiles or rockets since the first one in 1998.

A South Korean military source said, "Even in some advanced countries, rockets have exploded on their launch pads. That doesn't mean the North's missile technology has regressed."

"It's true that the North's long-range rockets still lag far behind those in the West in terms of appearance, but it seems that the technology has gradually improved since 1998," a rocket expert said.

englishnews@chosun.com / Apr. 16, 2012 12:27 KST

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