Thursday 4 February 2016

[UPDATED] North Korea's upcoming satellite launch

North Korea's previous satellite, Kwangmyŏngsŏng 3-2, imaged in 2015
(click image to enlarge)

On February 8th, 2016, it will be the 70th anniversary of the formation of the Provisional People's Committee for North Korea by Kim Il-Sung, effectively marking the birth of the nation. And 16 February 2016 will be the 74th (actually 75th) birthday of the late Kim Jong-Il, while in addition February 14th is a day that commemorates Kim Jong-Il assuming the role of "Grand General of the DPRK". Such dates often see some significant national posturing of North Korea.

Following a nuclear test on January 6th (claimed to be a small H-bomb by the North Koreans, although western observers doubt this), North Korea has announced the launch of a satellite, with issued Broadcast Warnings pointing to a launch between February 8 and 25. The launch period starts at the date of the 70th anniversary of the Provisional People's Committee.  

Satellite image analysts at the 38 North website had already been documenting preparations for a launch at the launch site in Sohae in January. Over the past 3 year, North Korea had been making several improvements to its launch installations, building various new structures on the site.

Meanwhile, the upcoming launch has western nations and neighbouring states concerned. Especially Japan has expressed very strong concerns about the launch. Like they did in 2012, they have threathened to shoot the rocket down if it seems to be headed for Japan. That is unlikely to happen though.

The Broadcast Navigational Warnings issued delineate three splash-down areas of rocket debris:

DNC 23.
   A. BETWEEN 35-19N 36-04N AND 124-30E 124-54E.
      33-16N 124-11E, 32-22N 124-11E,
      32-21N 125-08E, 33-16N 125-09E.
      19-44N 123-53E, 17-01N 123-52E,
      17-00N 124-48E, 19-43N 124-51E.

[added note: the original letter of North Korea to the Int. Maritime Organization on which this navigational warning is based, is here].

Area A is the splash-down area for the first stage, area B for the fairings, and area C for the second stage (the third stage will remain on-orbit after launch). Plotting these on a map (red boxes in map below) reveals them to be on a north-south line with azimuth ~180 degrees (yellow line), avoiding the main islands of Japan:

(click map to enlarge)

The ~180 degree launch azimuth points to a satellite launch into Polar orbit, very similar to the launch direction of North Korea's previous satellite, Kwangmyŏngsŏng (KMS) 3-2 (2012-072A) three years ago (a nice background piece on that launch by Brian Weeden discussing "satellite launch or missile test?" can be found here). Compare my map above to the map constructed from the NOTAM's for the KMS 3-2 launch in 2012 on Bob Christy's website, [edit: and see also the comparison of 2012 to 2016 in this blogpost by Melissa Hanham on the Arms Control Wonk blog].

As was the case with their previous KMS 3-2 launch, the intended satellite orbit is, given the launch direction, likely a sun-synchronous orbit with an orbital inclination of 97 degrees. The launch direction due south rather than directly into a ~97 degree inclined orbit has been chosen to avoid overflying (and debris landing on) the territories of China and Taiwan during the ascend phase. In order to reach a true sun-synchronous orbit with inclination ~97 degrees, it necessitates a dog-leg manoeuvre of the third stage with payload during the final phase of the ascend to orbit (blue line in map above, approximate only). Orbit insertion of the payload will be about ten minutes after launch, just before reaching the Phillipines.

Assuming the resulting orbit of the satellite will be similar to that of KMS 3-2 in 2012 (perigee ~495 km, apogee ~588 km, inclination 97.4 degrees), the trajectory of its first revolution around earth will look something like this (yellow dot shows satellite position one hour after orbit insertion):

(click map to enlarge)

The launch window is 17 days long, and runs daily from 22:30 to 03:30 UT, according to the Broadcast Warning. The daily 22:30-03:30 UT window is similar to that of the KMS 3-2 launch in 2012. It runs from local daybreak to just short of local noon, indicating a desire for an orbital plane resulting in morning passes.

[edit: the paragraph below was slightly editted on 5 Feb 2016, expanding the discussion of possible launch times]

In 2012, KMS 3-2 was launched at 00:49:49 UT, almost exactly two hours after Pyongyang sunrise (22:50 UT). This suggests (if a similar orbital plane with overfly times at ~9h am local time is aimed for) that the current launch might happen somewhere between 00:24-00:41 UT, depending on whether the aim is for launch at a similar solar elevation (then it will be close to 00:24 UT) or merely two hours after Pyongyang sunrise (then it will be close to 00:41 UT). However (see the next paragraph), the timing of the 2012 launch also seems to have been (at least partially) dictated by a suitable window lacking overflights by western reconnaissance satellites. As for the date, I hesitate to prophecy on this, but I wouldn't be surprised if they go - weather permitting- for February 8, the first day in the 17-day window.

It appears that the North Koreans carefully chose their launch moment in 2012. US military sources already had claimed shortly after the launch that North Korea had played a ruse on them and evidently knew when western optical imaging satellites had (and had not had) view of the launch installations. This seems to be confirmed by my independent analysis of that launch from December 2012, which showed that the North Koreans used the very end of a longer-than-usual one-hour gap in IMINT coverage of the launch site to launch. And as I wrote in that blog post, a North Korean IP address had been looking for orbital elements of  US optical and radar satellites on this very blog just days before the launch.

The ruse was apparently designed to keep the USA, Japan and South Korea in the dark about the launch moment until the actual moment of launch itself (which would be registered by SBIRS and DSP satellites), as a counter-measure to give potential intercepts of the rocket as little advance preparation time as possible.

It would be difficult for North Korea to repeat such a ruse these days, as the number of western optical and radar reconnaissance satellites has grown ubiquitously in the past three years. Assuming launch near 00:40 UT (two hours after sunrise), the most promising dates (from the perspective of relative lack of western IMINT coverage) are three dates in the first week of the launch window:  February 8, 10 and 14. But maybe North Korea is confident enough this time, following the experience with KMS 3-2, to not bother with western IMINT coverage at all.

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