Saturn interstage falling off, click here to watch the complete video

I wish I knew what the 2006 Tae’podong-2 looked like. My guess is that it was very different, at least in the details, than yesterday’s Unha-2 launch. Why do I say that? Because I’m starting to see a pattern in North Korean and Iranian missile development programs that are more different than they are similar. Of course, my guess about the 2006 Tae’podong-2 is somewhat circular but nevertheless…

I posted a while ago about Why We Test Things and the upshot was that we, in the West, only flight test things if we are pretty sure how they are going to go. But a failure can usually be attributed to a single cause that most likely is associated with the integration of the entire weapon. For instance, the Trident shown on that post was apparently going in a crazy spiral because a wave slapped the nozzle as it left the surface of the water. The Falcon-1 failed, on at least one of its test flights, because fuel left in its regeneratively cooled engine continued to give a small thrust that sent the first stage careening into the second and broke the second stage engine. In both cases, I would venture, the developers made a small change to the system and flew it again with essentially the same rocket in every other respect.

Iran seems to follow a similar, very systematic, development path. The August 2008 Safir launch reportedly failed in its second stage. (My guess, based on very little information, is that it failed at stage separation/ignition.) The Iranians seem to have diagnosed the problem, made a correction to one part of the system, and flew essentially the same rocket in February 2009. And that followed at least one sounding rocket flight that seems geared to study staging separation.

What is North Korea’s record of responding to failures? It would have to be considered to respond to failures poorly. On top of a reputation of conducting very few flight tests, they also seem to always start over when they have a failure. (Perhaps they “change” project managers?) The Tae’podong-1, flown in August 1998, apparently failed in its third stage. Instead of correcting that failure and retesting, they built the Tae’podong-2. The Tae’podong-2 failed (probably spectacularly) in 2006 just 40 some seconds after launch. Now, the Unha-2 failed sometime after its second stage ignited. (I consider that a strange place for it to fail. A failure during separation, with all the pieces landing in the same spot as the first stage, would have been more understandable.) Did North Korea start over from scratch with the Unha-2? That’s why I’d like to know what the 2006 Tae’podong-2 looked like. Unfortunately, there is no real information on what it looked like in the public domain.

Update: (1:35 pm EDST) Reports are starting to come in that the Unha-2 failed after the second stage burn was complete with the second stage splash down inside the predicted zone. That makes a lot more sense to me than a failure somewhere in the middle of the second stage burn.

Update: (9:30 am EDST, 4-7-09) Here is an example of the printed reports that have started to surface, though I’ve been told less formally by others as well. I’ve plotted the “range” of the second stage as reported in these media stories here.