12/13/2012 - 07:42

Underestimated or overestimated? North Korea’s satellite launch in perspective

David Wright

David Wright

A physicist, Wright codirects the Union of Concerned Scientists' (UCS) Global Security Program. His expertise is in...

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Despite supposed technical problems with its rocket, North Korea surprised the world this week by launching its Unha-3 rocket and successfully placing a satellite into orbit.

The launch -- using the same rocket, satellite, and trajectory -- was a repeat of last April's attempt, which failed. Overall, it was North Korea's fifth attempt to launch a satellite, and its first success.

Timeline of launches. North Korea's first attempt to launch a satellite into space was in August 1998 with the three-stage Taepodong-1 launcher, which used a version of the Nodong missile as a first stage. In that case, all three stages ignited, but the third stage apparently went out of control and disintegrated before reaching orbit.

The next attempt in July 2006 failed less than 40 seconds after launch, and little is known about it. Powered by a cluster of four first-stage Nodong engines, this rocket launcher is believed to have been much larger than that used in 1998, which only had used engine in the first stage. The four-engine configuration has been used since 2006.

In April 2009, North Korea launched the Unha-2 launch vehicle. Though the first two stages of the three-stage rocket appeared to work, the upper stage and satellite fell into the ocean. This launch sparked international outcry since it was fired on a path that carried it east over Japan. The April 2012 attempt was instead launched south from a new launch site on the western coast of the country, following a path similar to that of South Korean launches. That attempt had problems with the first stage and apparently the second stage did not ignite.

In advance of the 2009 and both 2012 launches, North Korea announced a launch window and zones where it expected the empty first and second stage bodies to fall to Earth after they separated from the rocket. This is standard procedure to warn air and sea traffic in the region when a country is planning a launch, and suggested Pyongyang seemed to be trying to act like a responsible country developing a space program.

Post-launch analysis. The Unha-3 missile, which is a slight modification of the Unha-2, in principle is capable of reaching parts of the continental United States with a payload of half a ton or more if the country modified it for use as a ballistic missile. With this week's launch, the fact that the first two stages appear to have fallen in or near the declared zones gives some evidence that the first part of the launch went as planned. In addition, North Korea announced that the satellite was expected to be placed in orbit at an altitude of about 500 kilometers, and initial tracking information shows that the satellite is in a nearly circular orbit with minimum and maximum altitudes of 494 kilometers and 588 kilometers, respectively.

What was somewhat surprising is that the third stage apparently maneuvered to move off the launch trajectory (which had an inclination of about 88 degrees) and place the satellite in a sun-synchronous orbit with an inclination of 97.4 degrees (sun-synchronous orbits are a particular class of orbits with special properties that make them useful for Earth-monitoring satellites). North Korea had announced this was its intent before its April launch, but many observers doubted the country had the technical sophistication to control the behavior of the third stage to the extent needed to be successful.

The satellite is believed to be relatively simple, and probably includes a low-resolution camera. But it would give North Korea experience communicating with it and controlling it in orbit. However, less than 24 hours after it was placed, reports began to surface that US officials believe it is tumbling in orbit. If so, the satellite may be unable to point its antenna toward the Earth and therefore would be out of communication. This suggests that the launch was not as successful as originally thought.

Game changer in Asia Pacific? Despite this apparent problem with the satellite, North Korea was still able to beat South Korea into orbit. South Korea is in the process of developing its own space-launch capability, and has attempted two unsuccessful launches in recent years and postponed a third attempt from this fall to next spring due to technical problems. The prospect of placing an object into orbit before Seoul was able to do so may have been an important factor driving the timing of the North's launch.

The question most people are asking is what this success implies about the state of North Korea's missile development program. While the success may have political importance, it means little from a technical perspective. It has been clear from its past launches that North Korea has been able to build or buy working components for a rocket, and that it has assembled those components into a design that, in principle, should work. The main stumbling block for North Korea has been the enormous complexity of rockets, and getting all the parts to work together and at the same time. Even if the probability of that happening is small, there is some chance that it will happen, but that does not imply a technological advance or mean that future launches are any more likely to be successful. So even with this success, North Korea has little confidence in the reliability of the rocket, which undermines its utility for military purposes.

Despite that, as a colleague of mine mused following the launch, "now we're likely to see people go from underestimating the capability of North Korea's program to overestimating it." Neither caricature of Pyongyang's development program is helpful for developing a serious response to the launch. The impulse by some in the United States and elsewhere to call for missile defense as a technical fix for the problem is misplaced -- like it or not, there is no technical fix.

North Korea has shown over the years that it can make slow but real progress toward improving its rocket program. As frustrating as diplomacy can be, the world has little choice other than engaging Pyongyang to try to reduce this threat. And despite this successful launch, there remains time for that process.