USA 129 15.0 3.0 0.0 5.3 v 1 24680U 96072A 05261.07910296 .00015389 00000-0 20697-3 0 08 2 24680 97.9604 323.2370 0520197 219.8146 136.3798 14.74426052 04 Arc 2005 Sep 14.83 - 18.09, WRMS residuals = 0.015 deg Brief Introduction To TLEs And Satellite IDs: http://www.satobs.org/element.html I have been looking ahead to estimate the likely timing of USA 129's next phasing re-boost, relative USA 161 (01044A / 26934). USA 161's orbital plane is about 44.6 deg east of USA 129's, causing it to follow roughly the same ground track as USA 129, nearly 2 orbital revolutions later. As the appended table shows, until 2004 August, USA 161's ascending node crossing was not allowed to lag USA 129's by more than about 2h40m. This was accomplished by boosting USA 129 slightly whenever USA 161 began to lag by more than 2h40m, enabling USA 161 to begin to catch up. Since USA 129's orbit has a much greater rate of decay than USA 161's, it will eventually pull too far ahead, necessitating another reboost. Beginning in 2004 November, three of USA 129's four reboosts have occurred when USA 161 was lagging by much less than the previous 2h40m. The 2006 Jul 21 lag was the lowest yet for a reboost: 2h16m. I do not know the reason for this change, but it must be taken into account when attempting to forecast future reboosts. Accordingly, and based upon recent orbital elements of USA 129 and USA 161, USA 129's next phasing re-boost could occur as soon as Oct 15 UTC. Ted Molczan I have reviewed all of the USA 129 (96072A / 24680) reboosts during the life of USA 164 (01044A / 26943) for which I have orbital elements. The results are summarized below: 01044A lag 96072A boost UTC Lat h:mm:ss --------------------------- ---------- 2002 Apr 04 16:27 00.17 S +2:41:41 2002 Jun 27 15:09 81.45 N +2:40:31 2002 Sep 12 16:35 14.52 S +2:45:44 2003 Jan 17 14:03 39.72 N +2:39:00 2003 Mar 27 15:46 81.39 S +2:46:00 2003 Jun 05 18:44 42.13 N +2:40:39 2003 Aug 07 13:58 16.61 S +2:37:09 2003 Oct 16 14:33 31.89 S +2:48:44 2003 Dec 18 12:54 57.99 N +2:42:16 2004 Feb 12 17:34 60.42 N +2:44:06 2004 Mar 18 17:43 06.00 S +2:42:31 2004 Mar 23 14:16 09.74 N +2:42:16 2004 Jun 17 13:55 72.28 S +2:46:57 2004 Aug 26 15:21 29.90 N +2:40:19 2004 Nov 18 14:43 61.63 N +2:24:36 2005 Feb 03 16:49 49.42 S +2:36:38 2005 May 05 15:05 62.09 S +2:27:33 2005 Jul 21 15:14 49.20 N +2:16:20 The reboost times ranged between 12:54 and 18:44 UTC, about a 6 hour span, that seems to fit nicely into someone's 8 h workday. ------------------------------------------------------------------------- Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive: http://www.satobs.org/seesat/seesatindex.html
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