Lacrosse 5 elements

From: Ted Molczan (seesat@rogers.com)
Date: Fri Feb 10 2006 - 11:45:59 EST

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    The first four Lacrosses established frozen orbits not long after launch, but
    Lacrosse 5 has yet to do so, more than 9 months after its launch. The principal
    benefit of frozen orbits is that altitude versus latitude remains constant.
    
    Perhaps Lacrosse 5's SAR signal processing has been designed not to require such
    a precise orbit. The Lacrosse program is more than 20 years old, so it seems
    reasonable to expect some changes in design; another example being Lacrosse 5's
    abandonment of the gold coloured thermal blanket that gave its predecessors
    their distinctly reddish hue.
    
    Another new feature of the orbit is the small negative decay term that has been
    evident for quite a few weeks. My guess is that this is a perturbation resulting
    from Lacrosse 5's almost exact 43:3 resonance. The effect probably has been
    present since launch, but may have been masked initially by decay due to
    atmospheric drag, which has been subsiding as we move away from the recent solar
    max.
    
    Finally, I noted an apparent small manoeuvre between 2006 Jan 14.75 and Jan
    15.87, the main effect of which was to increase the argument of perigee by about
    70 deg.
    
    Lacrosse 5      15.0  4.0  0.0  2.5 v
    1 28646U 05016A   06041.20909589 -.00000032  00000-0 -76212-5 0    04
    2 28646  57.0132 141.9770 0002088  10.9211 349.1848 14.53345115    06
    Arc 2006 Jan 15.87 - Feb 10.23, WRMS residuals = 0.015 deg
    
    1 28646U 05016A   06014.72684825 -.00000041  00000-0 -97285-5 0    07
    2 28646  57.0120 241.0145 0002089 256.1323 103.9458 14.53346794    07
    Arc 2006 Dec 24.76 - Jan 14.75, WRMS residuals = 0.018 deg
    
    Brief Introduction To TLEs And Satellite IDs: http://www.satobs.org/element.html
    
    Ted Molczan
    
    
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