GSSAP pre-launch elements for 2016 Aug 19 UTC

From: Ted Molczan via Seesat-l <seesat-l_at_satobs.org>
Date: Thu, 18 Aug 2016 19:54:54 -0400
I apologize for posting this so close to launch.

Two Geosynchronous Space Situational Awareness Program (GSSAP) satellites are scheduled for launch from CCAFS on a Delta
4 Medium+ 4,2 rocket, on 2016 Aug 19, at 04:47 UTC. Observers in parts of the western hemisphere may be able to observe
the Delta 4 second stage's fuel dump in GEO.

http://spaceflightnow.com/2016/08/17/d375_journal/

The following elements are based on launch at the above time.

LEO coast                                                258 X 272 km
1 73701U 73701A   16232.21678246  .00000000  00000-0  00000-0 0    09
2 73701  27.2800 217.7170 0010000 183.0000 359.3500 16.05000000    04

If the GTO burn occurs at the first ascending node, as it did on the first GSSAP launch in July 2014, then the following
TLEs apply:

GTO burn at 1st ascending node                         278 X 36398 km
1 73703U 73703A   16232.24746951  .00000000  00000-0  00000-0 0    05
2 73703  27.2800 217.4770 7307000   3.4000 359.6000  2.23480000    05

Delta 4 second stage in final orbit                  36134 X 36215 km
1 73704U 73704A   16232.48888890  .00000000  00000-0  00000-0 0    02
2 73704   0.4851  47.8577 0009503   3.2888 358.9484  0.98907630    08

The 73703 GTO TLE is fairly rough, but may be sufficient to spot the stack as it approaches GEO altitude.

The 73704 TLE is derived from Mike McCants' TLE of the Delta 4 second stage of the first GSSAP launch, which was based on
observations. If the mission is a carbon-copy, then this will be highly accurate for spotting the fuel dump, which would
occur near the epoch of the 73704 TLE: 2016 Aug 19 at 11:44 UTC, near 94 W. Mike McCants and Ed Cannon observed the fuel
dump of the first GSSAP at the same mission elapsed time, 6h57m.

If the GTO burn occurs at the first descending node, then the following approximate TLE applies:

GTO burn at 1st descending node                        278 X 36398 km
1 73702U 73702A   16232.21704857  .00000000  00000-0  00000-0 0    09
2 73702  27.2794 217.7115 7307042 182.7762   0.0513  2.23480002    02

The stack would arrive at GEO altitude at about 10:34 UTC near 93 E. The circularization burn would occur soon after,
followed by the Delta 4 second stage fuel dump perhaps 20 min. later.

Ted Molczan


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Received on Thu Aug 18 2016 - 18:55:35 UTC

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