WGS 9 search elements - revised

From: Ted Molczan via Seesat-l <seesat-l_at_satobs.org>
Date: Sat, 18 Mar 2017 13:17:44 -0400
Note: I have revised my estimate of the MECO-2 orbit to better fit the published mission events timeline and ground
track, and have added an estimated MECO-3 orbit for the 2nd stage de-orbit.

The launch of Wideband Global SATCOM (WGS 9) from Cape Canaveral on a Delta 4 Medium+(5,4) is scheduled for a 75 minute
window that opens on 2017 Mar 18 at 23:44 UTC.

https://spaceflightnow.com/2017/03/17/d377_journal/

I offer the following rough TLE of the orbit after the second burn of the 2nd stage, assuming launch at window-open: 

MECO-2 (payload)                                       434 X 44372 km
1 78920U          17078.01151621  .00000000  00000-0  00000-0 0    09
2 78920  27.0000   1.5000 7633000 174.0000   2.8500  1.77840000    06

The 2nd stage is scheduled to perform a 10.2 s de-orbit burn at T+1:11:44.6, or Mar 19 00:55:45 UTC, assuming launch at
window-open. The following TLE is consistent with the expected ocean-impact about 11 h later near 14 N, 156 E.

MECO-3 (2nd stage de-orbit)                           -141 X 40088 km
1 78921U          17078.03883105  .00000000  00000-0  00000-0 0    01
2 78921  27.0000   1.4928 7633000 169.0500  23.2500  2.03000000    09

The estimated delta-V of the de-orbit manoeuvre is about 176 m/s. I did not attempt to estimate the small out of plane
components that are likely to occur and would somewhat increase the delta-V. 

Ted Molczan


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Received on Sat Mar 18 2017 - 12:18:26 UTC

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