Updated elements

From: Ted Molczan (seesat@rogers.com)
Date: Sun Sep 18 2005 - 13:00:23 EDT

  • Next message: Russell Eberst: "Lunar eclipse of satellites"

    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
    



    This archive was generated by hypermail 2b29 : Sun Sep 18 2005 - 13:04:47 EDT