Lacrosse 5 elements

From: Ted Molczan (molczan@rogers.com)
Date: Sun May 01 2005 - 11:28:48 EDT

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    1. Orbits from observations
    
    Lacrosse 5       0.0  0.0  0.0  3.4 v
    1 71001U 05016A   05121.30567409  .00001317  00000-0  10000-3 0    03
    2 71001  57.0006 128.1443 0165730  17.3893 343.2720 14.91442536    05
    Arc 2005 Apr 30.04 - May 01.33, WRMS residuals = 0.040 deg
    
    Lacrosse 5 r     9.8  3.0  0.0  4.8 v
    1 71004U 05016B   05121.30509779  .00001315  00000-0  10000-3 0    00
    2 71004  56.9969 128.1380 0159329  16.8137 343.8090 14.92106992    06
    Arc 2005 Apr 30.04 - May 01.12, WRMS residuals = 0.029 deg
    
    2. Estimated Orbit of 05016A after Circularization
    
    The following search orbits are based on the assumption that the payload will
    circularize its orbit about 48 h after launch, on an apogee pass within range of
    Diego Garcia, as was the case with Lacrosses 2, 3 and 4.
    
    In the case of 05016A, that would be tonight, 2005 May 02 near 01:55:35 UTC.
    
    I note that 05016A's initial apogee appears to be greater than that of any of
    its predecessors:
    
            km
    88106B  687
    91017A  678
    97064A  676
    00047A  689
    05016A  709
    
    Assuming 05016A's higher apogee is intentional, and a nearly circular final
    orbit, then the following search orbit applies:
    
                                                             703 X 709 km
    1 70000U          05122.08026620  .00000044  00000-0  10000-4 0    07
    2 70000  57.0006 125.0644 0004000  18.7493 182.1000 14.56000000    03
    
    In the event 05016A manoeuvres to replicate 97064A's initial circularized orbit,
    the following applies:
    
                                                             670 X 676 km
    1 70000U          05122.08026621  .00000044  00000-0  10000-4 0    08
    2 70000  57.0006 125.0644 0004000  18.7493 182.1000 14.66200000    06
    
    I recommend the following observational plan.
    
    1. Prior to 2005 May 02 at 01:55:35 UTC, assume 05016A will not have manoeuvred,
    so use the 14.9144 rev/d elset derived from observations.
    
    2. After 2005 May 02 at 01:55:35 UTC, assume 05016A may or may not have
    manoeuvred, so look for it first in the 14.9144 rev/d orbit derived from
    observations. If it fails to appear, then expect its earliest pass in the 14.662
    rev/d search orbit, and its latest pass in the 14.56 rev/d orbit.
    
    It is recommended to plot all three predicted tracks.
    
    Ted Molczan
    
    
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