Updated elements

From: Ted Molczan (seesat@rogers.com)
Date: Sun Sep 11 2005 - 10:54:54 EDT

  • Next message: Robert Holdsworth: "Re: possible decay over NZ?"

    Lacrosse 5 made a small orbital manoeuvre, apparently sometime between Peter
    Wakelin's observation of 2005 Aug 09 UTC and Greg Roberts' of Aug 29 UTC. Its
    orbital altitude was raised very slightly, as was its eccentricity. I suspect
    the purpose was to establish a frozen orbit, such that the mean argument of
    perigee will always remain near 90 deg. This will be confirmed or refuted as
    tracking continues.
    
    Frozen orbits result in a nearly constant orbital altitude vs. latitude, which
    is desirable for imaging satellites. The Lacrosses are synthetic aperture radar
    imagers.
    
    All previous Lacrosse's have operated in frozen orbits. Those in 57 deg orbits
    have argument of perigee always near 90 deg; those in 68 deg orbits have
    argument of perigee always near 270 deg.
    
    USA 129         15.0  3.0  0.0  5.3 v
    1 24680U 96072A   05254.08830639  .00008831  00000-0  11872-3 0    02
    2 24680  97.9619 316.3379 0521288 242.4872 112.2447 14.74201987    04	
    Arc 2005 Sep 06.82 - 11.10, WRMS residuals = 0.017 deg
    
    Lacrosse 5       0.0  0.0  0.0  3.0 v
    1 28646U 05016A   05254.40101974  .00000043  00000-0  10210-4 0    08
    2 28646  57.0100 349.7125 0010463  79.7174 280.5019 14.53362530    08
    Arc 2005 Aug 29.72 - Sep 11.41, WRMS residuals = 0.008 deg
    
    Brief Introduction To TLEs And Satellite IDs: 
    
    http://www.satobs.org/element.html
    
    Ted Molczan
    
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