Last week, North Korea finally managed to put an object into orbit around the Earth after 14 years of trying. The event was greeted with hysterical headlines, about how the whole thing was a likely a missile test and most certainly a failure of Western intelligence. Most of those headlines were dead wrong.
There are many questions yet to be answered about this launch and what it means. Some of them will take weeks or months to determine, others may never be answered satisfactorily. But there's enough information already in the public domain to answer basic questions about the launch. News flash: Most of the initial reports about it were total misfires.
Was This a Ballistic Missile Test or a Satellite Launch?
Some of the same technologies are needed for long-range missiles and for space launches ' most notably rocket motors, high strength-to-weight fuselages, and guidance software. But they're not the same thing. All evidence points to a satellite launch, despite headlines like these.
The goal of a space launch vehicle is to insert payloads into orbit and to do so they must perform two functions. They must first lift a payload to a desired altitude above the Earth and then give that payload enough forward speed to remain in orbit at that altitude. The final speed required for this is determined by the altitude and pull of the Earth's gravity. With enough speed, the payload moves forward equal to the distance it is pulled towards the Earth by gravity. It moves in an ellipse around the Earth, continually falling towards the Earth but missing ('free fall').
Ballistic missiles, on the other hand, have a different goal. Their objective is to deliver a payload to another spot on the Earth. To do so, they need to accelerate the payload to a very high speed, although significantly slower than the space launch vehicle, and after separation from the rocket, the ballistic missile's payload follows an elliptical path through space similar to a satellite. However, the ballistic payload is not in orbit ' part of its elliptical path is inside the Earth's atmosphere. The payload coasts along its elliptical path and instead of 'free-falling' around the planet, it re-enters the atmosphere and impacts a spot on the surface of the Earth.
From a practical perspective, these different goals result in significant differences in the flight profile of a space launch versus a ballistic missile launch. Look at the illustration of the North Korean launch compiled by Dr. David Wright. The green trajectory in this illustration is for a ballistic missile trajectory while the red and yellow trajectory is for a space launch trajectory. The most striking difference is in the altitude ' a long-range ballistic missile actually goes much higher into space than a typical space launch into low-Earth orbit (LEO), sometimes as high as 1,500 kilometers (930 miles).
Within these parameters, the North Korean rocket launch was most certainly a space launch and not a ballistic missile test. This can be verified by multiple sources before, during and after the launch. Prior to the launch, North Korea notified international agencies of the splashdown zones for the first two stages and the payload shroud, as is standard practice. These splashdown zones corresponded to a space launch trajectory, indicating beforehand that the North Koreans planned to try and place a satellite into orbit. During the launch, heat from the rocket was picked up by constellations of U.S. military infrared satellites in orbit. Tracking of the burn phase of the launch by those satellites allows the U.S. to verify that it was on a space launch trajectory. After the launch, remnants of the first stage were recovered in the pre-announced splash zone by the South Korean Navy.
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