I have included Ted's TLE into a temporary page. Tracking can be attempted at the following link: http://www.satflare.com/track.php?q=temp_12D11A Regards, Simone >----Messaggio originale---- >Da: ssl3molcz@rogers.com >Data: 11-apr-2012 3.36 >A: <seesat-l@satobs.org> >Ogg: North Korea satellite: retrograde ground track displayed in launch control centre > >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: > >http://www.youtube. com/v/GpjGwG414rY&hl=en_US&feature=player_embedded&version=3 > >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 >Earth. > >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 fit to a couple of reasonable 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 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: > >http://satobs.org/seesat_ref/misc/NK-2012-retrograde-1a.jpg > >Here is a view near the ascent trajectory: > >http://satobs.org/seesat_ref/misc/NK-2012-retrograde-2a.jpg > >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): > >http://allthingsnuclear.org/post/20730991602/a-comparison-of-north-koreas- unha-2-and-unha-3 > >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 at -0.1730 deg/d; the 94.5 deg >orbit would precess 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 > > >_______________________________________________ >Seesat-l mailing list >http://mailman.satobs.org/mailman/listinfo/seesat-l > _______________________________________________ Seesat-l mailing list http://mailman.satobs.org/mailman/listinfo/seesat-l
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