From April 8-13, Western news media, including me, gained extraordinary access to the North Korean space program as it concluded its campaign to launch an Unha-3 rocket from the Sohae Satellite Launching Station near the Chinese border. That access made the final event all the more remarkable. The launch, performed in defiance of international law, ended in failure as the rocket disintegrated soon after takeoff.
Since then, analysts have tallied up the new details they learned. But it’s equally important to recognize what we still don’t know about the launch and the communist country’s rocket capabilities. Perhaps there are answers still to be found in the careful analysis of the news photographs and videos from the visits, or from new satellite imagery of the Sohae base. Perhapsnew conclusions by government analysts in South Korea and the US will filter out. In any case, here is a list of what I didn’t learn in North Korea.
1) We still do not know enough about the actual failure timeline, or potential causes, to select among a number of plausible failure modes. Worse, we don’t know whether the North Koreans themselves have access to diagnostic information that would inform their own investigation.
2) We do not know what became of the rocket debris that scattered across relatively shallow waters along the west coast of South Korea. Seoul has kept any recoveries, and any insights from examination of the debris, under extremely tight wraps.
3) We don’t know for sure what was under the aero shroud atop the rocket. Presumably it was the earth observation satellite, showed to Western journalists days before the launch, that was loaded atop the booster an astonishingly short time before launch. But North Korean officials, despite explicit promises to do so, have failed to provide any evidence that the satellite was installed as claimed.
The shrouded component is important because it could either bolster or disprove North Korea’s assertion that their rocket wasn’t a “weapons test.” If, for example, it was a heat-shielded re-entry vehicle (RV), the April 13 flight could have provided perfect cover for dropping the test RV back to Earth.
4) The actual functions of the Sohae “Launch Control Center” remain obscure. The configuration presented to foreign journalists on April 8 was eerily evocative of a micro Potemkin village in its combination of office desks, cafeteria chairs, ordinary telephone headsets, and flat-screen displays. Several operators were seated out of reach of their keyboards, and twice as far from the display screens as is the norm in other countries. There were no obvious controls for selecting voice loops, displaying warning flags, or even choosing among available video channels.
5) There are some equally nagging questions about the General Satellite Control Center outside of Pyongyang. Most striking is one official North Korean news agency photo from the front of the control room looking back at the visitor gallery, that showed the bulky white consoles had no backs and were mostly empty inside.
6) The architecture of the displayed “Bright Star 3″ satellite and its lack of any apparent environmental protection raises several questions. The most serious is whether the solar arrays, seen on the three visible sides of the satellite, hinge open to create a parallel three-segment solar array to maximize electrical power for the 3-axis stabilized spacecraft. Attempts to question officials at the unveiling were stymied by poor translators. Regarding the claim of an active attitude control system, it would be interesting to learn just how such a control system was implemented, such as cold gas jets or hydrazine thrusters. Such options raise the question of whether the satellites thruster feed tanks were loaded and pressurized while dozens of foreigners were crowding close around it.
7) What kind of orbit did the North Koreans really intend to reach? The incompatibility of the orbital planes defined first by the ascent ground track and then by the displayed Antarctic fly-over track remains unresolved. To get directly into the orbit claimed, the ascent groundtrack would have had to have been shifted significantly westward, while the plane that could be achieved by launching along the specified ground track was nowhere near “sun synchronous” (the path that maintains similar local lighting conditions at each ground site of interest, over the lifetime of the satellite).
What was the purpose of the launch pad mobile transport’s “railroad to nowhere”? The Sohae launch pad apron is elongated with the launch position at one end, and parallel recessed rails running from one end of the concrete apron to the other. For the April 13 launch, the Unha-3 must have been stacked on the launch platform, which was immobile, over the flame trench. But an explicitly promised larger booster, compatible with the 30 percent taller gantry tower at Sohae, would probably require construction of a Vertical Assembly Building at the other end of the pad apron, enclosing the other end of the mobile platform’s rails. The current pad layout now looks entirely compatible with a future addition of such a structure.
9) The full implications of the Sohae facility’s total dependence on the wheeled transport of components and propellant carriers remains undefined. The incoming rail line stops short of the assembly building, and after that it’s all paved road.
10) Why was the promised live display of the launching canceled? Good video from the launch site was reaching the General Satellite Control Center north of Pyongyang — we saw that video stream while visiting there — so why it could not be routed the small additional distance to the press center remains a mystery.
The world was promised answers — and proofs of innocence — for this launch, and the admission of so many foreign journalists was an astonishingly bold decision. But clumsy implementation and deliberate obstructionism betrayed such promises.
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James Oberg is the author of ten books on space flight, including Red Star in Orbit: The Inside Story of Soviet Failures and Triumphs in Space. He served as a space engineer at NASA’s Johnson Space Center in Houston as a contractor for 22 years. His last piece for Txchnologist considered the phenomenon of “space sight.”