Updated X-37B OTV-1 elements

From: Ted Molczan (ssl3molcz@rogers.com)
Date: Tue Jun 01 2010 - 14:51:28 UTC

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    Derek Breit, Tim Luton, Mike McCants, Steve Newcomb, Jim Nix, Alberto Rango,
    Brad Young, and I, contributed observations used to determine the following
    element set.
    
    OTV-1                                                    402 X 421 km
    1 36514U 10015A   10152.14625136  .00000000  00000-0  00000-0 0    06
    2 36514  39.9890 115.7066 0014500 288.9656  70.9583 15.52671698    01
    Arc 20100527.08-0601.16 WRMS resid 0.188 totl 0.020 xtrk
    
    It appears that the object manoeuvres frequently - probably several times
    per week, perhaps almost daily - in order to maintain a nearly constant
    mean-motion near 15.5267 rev/d. I base this on the rather large time
    residuals of our observations, which tend be a significant fraction of 1 s,
    much greater than the 0.1 s or better that we routinely achieve.
    
    I estimate that such drag-negating manoeuvres would require about 10 m/s
    total delta-V over the reported maximum mission duration of 270 days,
    probably accounting for no more than a few percent of the total available. 
    
    The launch weight of the X-37B is about 11,000 lbs (5,000 kg). A Sep 2003
    NASA Facts document (FS-2003-09-121-MSFC) claimed that the dry weight of its
    X-37 would not exceed 7,500 lbs (3400 kg). Assuming that is true for the
    X-37B (perhaps a big if), and if all of the wet mass is hydrazine
    propellant, than the total delta-V would be about 1,100 m/s, of which about
    100 m/s would be required for de-orbit. I consider those fairly rough
    estimates; does anyone have better information?
    
    Ted Molczan
    
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