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 _______________________________________________ Seesat-l mailing list http://mailman.satobs.org/mailman/listinfo/seesat-lReceived on Sat Mar 18 2017 - 12:18:26 UTC
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