North Korea satellite: retrograde ground track displayed in launch control centre

From: Ted Molczan (
Date: Wed Apr 11 2012 - 01:36:53 UTC

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    Included in some of the video shot by journalists covering North Korea's upcoming rocket launch, are launch control
    display screens depicting a southbound ground track that to the eye looks close to that of a sun-synchronous satellite
    orbit. It has been discussed on the NSF and NK forums. I have been working to estimate the orbit implied by the ground
    track and to evaluate its consistency with the location of the launch site, NOTAMs, and other information issued by
    North Korea.
    The first images I saw had insufficient resolution or coverage to confidently estimate the orbit. Fortunately, late last
    night Charles Vick informed me of the following video, which is the clearest I have seen yet:
    The relevant scene appears for several seconds beginning at 01:56 elapsed time.
    Notice that the track begins on the other side of the Earth, rises above the northern limb, then proceeds south over
    China, the Korean peninsula and so on. The track appears to be a 3D representation of the initial orbit around the
    Based on a notional launch on 2012 Apr 12 at 02:30 UTC, and assuming a 500 km circular orbit, I estimate that the orbit
    is inclined approximately 94.5 deg:
    1 79802U          12103.11415511  .00000000  00000-0  00000-0 0    05
    2 79802  94.4500 182.0500 0002000 359.9726 179.8827 15.21000000    00
    I estimated the inclination and RAAN by trial and error fit to a couple of reasonably clear land marks visible on the
    display. Since the orbit has been plotted as a 3D representation, there is potential for parallax error in the ground
    track, but it is mitigated by the more or less perpendicular vantage point. I estimate the RAAN and inclination are
    accurate to within several tenths of a degree.
    The epoch is of no special significance; it and the mean anomaly have been chosen to place the orbit near the launch
    site about 4 min after lift-off, which is a useful rule of thumb to estimate the location of a newly launched satellite
    within its orbit.
    I was especially interested to determine whether the 94.5 deg orbit intersects with the 88.7 deg inclined ascent
    trajectory, and whether the location is plausible for the 3rd stage firing. Here is a plot of both trajectories:
    Here is a view near the ascent trajectory:
    The point of intersection is near 28.25 N, 124.5 E, about 1270 km downrange of the launch site, which seems to be in
    rough agreement with the plot of altitude vs. range in this recent analysis by David Wright (see Fig.2):
    The orbit is not sun-synchronous, but better than the 88.7 deg orbit implied by the NOTAMs, for the stated purpose of
    the satellite. Sun-synch orbits precess +0.9856 deg/d. The 88.7 deg orbit would precess -0.1730 deg/d; the 94.5 deg
    orbit +0.5917 deg/d.
    To be precisely sun-synch, a 500 km orbit must be inclined 97.4 deg. The apparent nearly 3 deg deficit may be an
    indication of the performance limitation of the launcher. I do not exclude the possibility that the displayed track was
    faked to mislead the news media, but it should not have been more difficult to produce a high-fidelity fake, assuming
    the work was done by the trajectory specialists. Considering the relative position of the numerals 4 and 7 on a keypad,
    a simple, honest typo also cannot be excluded.
    Ted Molczan
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