Korean satellite misses orbit

Third time unlucky as payload plunges into the Pacific.

It was meant to broadcast a booming anthem to leader Kim Jong-il, but if it did it was heard only by sea nymphs ringing its knell. On 5 April, North Korea's third attempt at a satellite launch, like its predecessors, dropped its payload into the Pacific Ocean. Preliminary analyses point to a failure in the rocket's third and final stage, which either did not ignite or did not separate properly from the second stage.

North Korea had hoped to join a growing club of entry-level space-farers. In February, Iran successfully launched a small satellite into low-Earth orbit using the Safir-2 rocket, and last September, a private company, Space-X of Hawthorne, California, launched a satellite aboard a booster it had designed from scratch, the Falcon 1.

Most observers believe that North Korea's rocket, known as TaepoDong-2, was more primitive than either of these, as it is based on the decades-old Russian and Chinese technology behind the Scud missile. Assuming that heritage, says David Wright, an arms-control analyst with the Union of Concerned Scientists, a non-profit group based in Cambridge, Massachusetts, the booster would weigh about 80 tonnes, three times the weight of Iran's rocket. Its engines probably used a relatively low-impulse combination of kerosene fuel and nitric-acid oxidizer, whereas the Falcon uses liquid oxygen.


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Those limitations do not mean that such a rocket could not work; it simply didn't work this time. The newest version of the TaepoDong-2 lifted off from the Musudan-ri launch site at around 2:30 a.m. GMT. Shortly after the launch, the state-run Korean Central News Agency reported that the rocket's payload, a communication satellite, had successfully reached orbit and begun transmitting the "Song of General Kim Jong-il". But a terse statement by the US Northern Command six hours later — by which time any satellite should have circled Earth a few times — said that "no object entered orbit". Citing diplomatic sources, the South Korean newspaper Chosun Ilbo reported that the rocket's first stage had landed in the Sea of Japan, whereas its remaining stages crashed some 2,700 kilometres farther out in the Pacific (see graphic). The launch's trajectory did not lend itself to the amateur observations from the United States and Europe that often provide corroboration of military launches.

The fact that it got 3,200 kilometres downrange suggests that the first stage of the rocket delivered, according to Wright. That would probably require the synchronized firing of four powerful engines, he says, and "the fact that it worked is a big deal".

A failure between the second and third stages is not uncommon, adds Brian Weeden, a technical consultant with the Secure World Foundation, a non-profit group based in Superior, Colorado. The separation of stages is a "very delicate operation" that requires explosive bolts and the third stage to ignite in careful sequence.

Whether North Korea can learn from its mistakes depends largely on what its developers gleaned from the rocket before it went down, says Jonathan McDowell, an astronomer at the Harvard–Smithsonian Center for Astrophysics in Cambridge, Massachusetts, who keeps tabs on rocket launches. No direct telemetry could have been received back in Korea after the rocket disappeared over the horizon. A support vessel in the Pacific tracking the flight would have solved that problem, but it is not clear whether North Korea has this capability. If it does not, then "it's just really hard for them to figure out what happened to their own rocket", McDowell says.

Given America's superior monitoring capabilities, "I'm almost sure that the United States knows more about what caused it to fail than they do," says Geoffrey Forden, an international security researcher at the Massachusetts Institute of Technology in Cambridge.

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Brumfiel, G. Korean satellite misses orbit. Nature (2009). https://doi.org/10.1038/458685a

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