For a discussion of all technicalities connected with the Korean launch–from its military implications to the launch plan–I highly recommend the preview physicist David Wright had in the Bulletin of the Atomic Scientists last week. Wright, who is codirector of the global security program at the Union of Concerned Scientists, is unsure whether the rocket’s beefed-up third stage would be able to carry a relatively heavy nuclear warhead (in place of a small satellite). “But if the third stage could be married to such a warhead, a three-stage ballistic missile based on this technology could theoretically carry it 10,000 km to 11,000 km,” says Wright. “Such a range would allow it to reach the West Coast of the United States. If a one-ton warhead were launched on the first two stages of this rocket, it might reach a distance of 8,000 km.”
I am particularly struck by one rudimentary but perhaps telling element in Wright’s analysis. Among other things, he points out that the three-stage rocket was launched on an almost due-south trajectory so as to avoid flying over nearby landmasses, notably Japan. That means the the rocket got no boost from the earth’s rotation, making it harder to loft the payload and requiring therefore more propellant.
In fact, North Korea is none too optimally placed to launch long-range missiles to begin with. Situated roughly between 38° and 40°, it is at a high latitude compared to the sites from which most long-range rocket launching is done. Cape Canaveral is just above 28°, the South American site where France does its commercial Ariane launching at about 5°. (The closer a site is to the equator, the greater the acceleration, because a point on the earth’s surface near the equator is spinning at a higher speed than points further from the equator.)
The decision to make a satellite launch attempt under sorely constrained geographic and geopolitical conditions, together with the bizarre circumstance of the decision’s being made even though the U.S. government had warned a launch would torpedo what had seemed a breakthrough deal, suggests–to me anyway–an alarming disarray and incompetence on the part of North Korea’s leadership.