Countdown to Pyongyang’s Missile Launch: Unha Rocket Stages at Assembly Building


Preparations for a new North Korean rocket launch appear to be underway at the Sohae Satellite Launching Station (commonly referred to as Tongchang-ri) located on its west coast. Based on DigitalGlobe satellite imagery released on November 23 and 26, trailers carrying the first two stages of an Unha (also referred to as the Taepodong-2) rocket were spotted parked near the main missile assembly building, a clear indicator that the rocket stages are being checked out before moving to the pad for an eventual launch.[1]

Other launch-related activities are ongoing. Empty tanks spotted at four locations indicate that the propellant buildings at the pad have likely been filled in preparation for the fueling of the rocket. The instrumentation site for monitoring a launch is still incomplete—one temporary building with a possible antenna has been established at the site, but instrumentation trailers are still parked near the assembly building. There is increased activity at buildings used to house VIPs in the past, including construction of temporary covered parking structures. Additionally, major improvements have been made to the observation building and grounds.

Exactly why Pyongyang is moving towards firing a long-range rocket at this time of year, contrary to past practice when launches typically occurred in spring or summer, remains unclear. Speculation has focused on North-South competition prompted by the South Korean satellite launch that was planned for November 29. If Pyongyang follows past practice in preparing for a launch, it could be ready to fire a rocket as early as the end of the first week in December. However, past practice has also been to announce dates and hours for sea or air closure areas for the rocket’s first and second stage impact areas, and to file for a frequency plan for a satellite in advance. Since that has not happened yet, the window would appear to be closing for an early launch.

Rocket Stages Undergo Checkout

New satellite imagery of the Sohae facility indicates that the Unha rocket has not yet been moved to the launch pad. Rather, trailers used to transport the first and second stages of the rocket are parked in the dirt motor pool area just to the west of the large assembly building (see figure 1). Their presence near the building indicates that the rocket is still inside undergoing the “check out process.” (The rocket stages are joined together and their various subsystems are activated to insure they will work after being moved to the launch complex.) Once this process is completed, the trailers will then transport the two stages to the launch pad, where they will be stacked on top of each other and fueled prior to launch. The third stage and payload are smaller and no unique trailer has been identified for them; however they will also be transported to the pad in the same manner.

Figure 1. First and second stage trailers near the main assembly building.

Image © 2012 DigitalGlobe Inc.

There is not much activity at the launch pad itself. The shadow of the gantry on both the November 23 and 26 images shows the Unha is not present. However, the crane on the top of the gantry tower has moved between these dates, indicating some activity has or is taking place (see figure 2).

Figure 2. Crane activity at the launch pad.

Image © 2012 DigitalGlobe Inc.

Launch Pad Propellant Buildings Filled

Based on the November imagery, the four rocket propellant buildings near the launch pad appear to have been filled and ready to fuel the rocket (see figure 3). Probable empty fuel and oxidizer tanks are present at four locations. There appear to be covered tanks—approximately 20 of two different sizes—across the road from the rail station, in a recently completed facility (top right). Empty tanks also appear present in an area that was once a military construction camp across the road from the media parking lot (top left). The empty tanks are likely ready to be shipped back to chemical plants to eventually be refilled; a probable set of empty tanks ready to be shipped appear on the rail siding (bottom right). In addition, there are a few tanks still near the propellant storage buildings at the launch pad along with a set of four larger tanks covered by an orange tarp (bottom left).

Figure 3. Probable empty fuel and oxidizer tanks. 

Image © 2012 DigitalGlobe Inc.

Other Developments

There are several indicators reinforcing the conclusion that preparations are ongoing for an upcoming test.

There is activity at the rail station, probably the most since the aftermath of the failed Unha-3 launch in April 2012 (see figure 4). On November 23, there were four vehicles and a truck-mounted crane present. (The truck-mounted crane was last seen on the large screen video displayed at the satellite control center prior to the April launch during the media visit. Located at the pad’s propellant buildings, it was used to unload and load the tanks off the delivery trucks.) Three days later, the crane is still present but has moved, as have three trucks, a bus and three other vehicles probably used to transport arriving workers and materials to the complex’s facilities.

Figure 4. Train station activity.

Image © 2012 DigitalGlobe Inc.

Imagery of the instrumentation site shows that, while it does not yet have its full complement of equipment, one of the small temporary buildings the DPRK establishes prior to a launch is present with a possible antenna (see figure 5). Other instrumentation vehicles appear to still be at the assembly building. They would need to be moved to the site prior to a launch. When the site was viewed in late September 2012, there was no building present or activity seen.

Figure 5. Preparations at the instrumentation site.

Image © 2012 DigitalGlobe Inc.

There is increased activity at the buildings the North Koreans have called “hotels,” used to house visiting VIPs and guests. Three temporary covered parking structures appear to have been erected at the VIP hotels, probably to keep snow off visiting dignitaries’ vehicles (see figure 6).

Figure 6. Improvements at VIP hotels. 

Image © 2012 DigitalGlobe Inc.

Finally, a new structure has been built near the observation building and the parking lot completed. There appears to have been roof construction or repairs done to the observation building itself, with probable cameras now mounted also to observe and record the launch (see figure 7).

Figure 7. Improvements at observation site.

Image © 2012 DigitalGlobe Inc.

Next Steps

Since Pyongyang’s satellite and long-range rocket tests have typically been conducted in the spring and summer, probably because of better weather conditions and longer days (there is no lighting on the pads), the upcoming launch represents a departure from past practice. Exactly why the North has decided to move forward with a launch this time of year remains unclear, although speculation has focused on Pyongyang seeking to match the South Korean launch that was planned for November 29. Whatever the reason, given the current state of preparations, the North could be ready to fire a rocket as early as the latter half of the first week of December, weather permitting.

If Pyongyang moves forward according to past practice, we can expect to see the following sequence of events over the next two weeks:

  • Transport of the 1st stage by trailer from the assembly building to the launch pad, followed by the stacking of the stage on the mobile launch pad using the gantry overhead crane.
  • Transport of the 2nd stage to the launch pad by trailer and stacking of the 2nd stage onto the 1st stage using the gantry crane.
  • Transport of the 3rd stage and payload to the launch pad and stacking of the 3rd stage onto the 2nd stage using the gantry crane.
  • Checkout of the complete Unha rocket and payload at the pad.
  • Conduct of a full launch readiness dress rehearsal. Gantry work platforms will be folded back with vehicles on the pad.
  • Possible built-in hold for weather or VIP schedules, with the Unha rocket inside the gantry work platforms that are covered with canvas.
  • Fueling of rocket stages and final pad checkouts.
  • Launch window of approximately 5 days (if like the Unha-3 launch in April) with possible arrival of VIPs the day before the launch.
  • On launch day, the final vehicle checkout occurs, the gantry platforms are folded back against the tower and the launch takes place.

This process took approximately 10 days for the April 2012 Unha-3 launch. That would make December 6 or 7 the earliest they would launch if this process started on November 27 or 28. However, Pyongyang’s past practice has also been to announce dates and hours for sea or air closure areas for the rocket’s first and second stage impact areas, and to file for a frequency plan for a satellite ahead of time. Since that has not happened yet, the window would appear to be closing for an early launch.

This article was made possible in part by a grant from the Carnegie Corporation of New York. The statements made and views expressed are solely the responsibility of the author(s).

[1] If this is a satellite launch it will probably be called Unha-4.

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