Updated NROL-129 elements

From: Ted Molczan via Seesat-l <seesat-l_at_satobs.org>
Date: Sun, 2 Aug 2020 13:37:43 -0400
The following elements have been derived through analysis of observations by Cees Bassa, Russell Eberst, David Hopkins,
Marco Langbroek, Mike McCants, Brad Young, and myself.

20712A                                                   569 X 580 km
1 99567U 20712A   20215.37143580  .00000592  00000-0  50000-4 0    07
2 99567  53.9762 208.3911 0007782 335.8979  24.1653 14.97640824    08
Arc 20200730.92-0802.4 WRMS resid 0.020 totl 0.011 xtrk

20712B                                                   569 X 580 km
1 99568U 20712B   20215.37219574  .00000591  00000-0  50000-4 0    04
2 99568  53.9801 208.4150 0007764 331.4180  28.6390 14.97579140    04
Arc 20200730.92-0802.4 WRMS resid 0.019 totl 0.013 xtrk

20712C                                                   570 X 580 km
1 99569U 20712C   20215.37353899  .00000264  00000-0  22418-4 0    03
2 99569  53.9759 208.3996 0006726 333.5641  26.5012 14.97459196    02
Arc 20200726.98-0801.92 WRMS resid 0.020 totl 0.014 xtrk

20712D                                                   572 X 579 km
1 99570U 20712D   20215.37704080  .00000584  00000-0  50000-4 0    00
2 99570  53.9632 208.3939 0005000 332.2108  27.8621 14.97128365    00
Arc 20200801.92-0802.4 WRMS resid 0.003 totl 0.003 xtrk

20712E                                                   573 X 579 km
1 99571U 20712E   20215.37762384  .00000584  00000-0  50000-4 0    02
2 99571  53.9738 208.4272 0004552 315.3101  44.7528 14.97097456    05
Arc 20200801.92-0802.4 WRMS resid 0.010 totl 0.008 xtrk

Objects D and E arrived several seconds late last night, indicating that they have manoeuvred. Their preliminary
post-manoeuvre elements show a reduction in the difference in their mean motion, perhaps an indication that they are
entering into a permanent formation. Time will tell.

The emerging consensus is that 20712C is the Minotaur 4th stage, based on optical characteristics.

Additional evidence is found in the elements. The satellite deployments occurred shortly after orbital insertion, which
was near apogee. First E, then D, appear to have separated in the direction of the velocity vector, which raised their
perigee relative the 4th stage. It appears that the 4th stage rotated 180 deg before ejecting A and B, which lowered
their perigee relative the 4th stage. 

There is precedent in the launch STPSat-2 and 5 other payloads, which were launched on a Minotaur IV:

https://www.nasaspaceflight.com/2010/11/live-minotaur-launch-multiple-satellites/

"Once the fourth stage has burned out, payload separations will begin. STPSat-2, the primary payload, will be the first
to separate and will do so sixteen minutes and thirty nine seconds into the mission. One minute later, RAX will be
ejected from a PPod CubeSat dispenser at the rear of the fourth stage, followed a minute later by O/OREOS from another
rear-mounted dispenser.

About a minute after O/OREOS separates, the fourth stage will make a 180 degree turn, in order to deploy FASTSAT against
the direction of flight. FASTSAT will separate two minutes later, and a minute after that the fourth stage will
manoeuvre to an attitude offset from its direction of flight by 150 degrees, and aligned with the elevation of its
velocity vector. Four minutes later, FalconSat-5 will separate from the rocket, followed five minutes later by both
FASTRAC satellites, which will be deployed together as one spacecraft. Thirty seconds later the rocket will manoeuvre
back to align with its direction of flight, and 150 seconds later the HAPS will separate from the fourth stage."

Ted Molczan


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Received on Sun Aug 02 2020 - 12:38:54 UTC

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