Updated X-37B OTV 1-1 elements

From: Ted Molczan (ssl3molcz@rogers.com)
Date: Thu Nov 25 2010 - 13:53:23 UTC

  • Next message: Russell Eberst: "2010NOV24.OBS"

    Greg Roberts made additional precise observations of OTV 1-1 on 2010 Nov 24, at 18:59 UTC. It was
    ~23 s late relative my estimated elements, which revealed that the orbit is about 1 km higher than
    the estimate. Here are revised and updated elements:
    
    X-37B OTV 1-1                                            281 X 292 km
    1 36514U 10015A   10328.74435517  .00024541  00000-0  55503-4 0    07
    2 36514  39.9869 104.9251 0007954 340.2040  19.8477 15.96461251    01
    Arc 20101123.79-1124.79 WRMS resid 0.041 totl 0.034 xtrk
    
    The mean motion and rate of decay remain a bit uncertain, but predictions should be accurate to
    within a few seconds per day since epoch.
    
    As with all of OTV 1-1's previous orbits, the ground track nearly repeats every few days, in this
    case, after 47 revs in 3 days, or a 47:3 resonance. Ground tracks that nearly repeat every 2, 3 or 4
    days are a common feature of U.S. imaging reconnaissance satellite orbits. Earth resources
    satellites also employ repeating ground tracks, but typically at intervals of at least several
    weeks, and with greater precision.
    
    Here is an update of OTV 1-1's altitude and ground track resonance history to-date:
    
                           Per  Apo  Grnd Track
                            km   km  Resonance
    2010 Apr 22 - Aug 09   403  420    61:4
    2010 Aug 09 - Oct 06   433  444    91:6
    2010 Oct 06 - Nov 01   390  395    46:3
    2010 Nov 01 - Nov 12   315  328    31:2
    2010 Nov 12 - present  281  292    47:3
    
    Total delta-V of the four orbit changes to-date is ~102 m/s. De-orbit from the present altitude
    would require ~84 m/s. Total delta-V has not been made public, but based on somewhat murky
    information on maximum orbital altitude, dry and wet mass, and fuel type, I estimate at least 700
    m/s.
    
    Ted Molczan
    
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