X-37B has manoeuvred; present orbit unknown

From: Ted Molczan (ssl3molcz@rogers.com)
Date: Thu Aug 19 2010 - 14:46:22 UTC

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    X-37B appears to have made a manoeuvre sufficiently large to require a planar search. This
    conclusion is based on Greg Roberts' unsuccessful attempts to observe it in its last known orbit, on
    the nights of Aug 14, 16, 17 and 18 UTC. There was considerable cloud on several of those nights, so
    it took some time to confirm that the object is not within several minutes (time) of a predictions
    based on its last known orbit.
    The last reported positional observations were by Brad Young, on July 29, near 02:46 UTC, in the
    following orbit: 
    OTV-1                                                    403 X 420 km
    1 36514U 10015A   10210.09309780  .00000000  00000-0  00000-0 0    09
    2 36514  39.9851 119.3456 0012533 356.3806   3.6913 15.52766118    04
    Arc 20100726.09-0729.12 WRMS resid 0.046 totl 0.018 xtrk
    The first reported no-show was by Greg Roberts, on Aug 14, near 20:52 UTC.
    X-37B reportedly can reach ~900 km altitude, which is more or less consistent with the low end of
    the range of my total delta-V estimates, assuming manoeuvre from 400 km circular to 900 km circular,
    return to 400 km circular, and eventual de-orbit.
    X-37B probably entered orbit will a full supply of fuel, and it had made only small orbit
    maintenance manoeuvres through July 29. We expected it to make a large manoeuvre eventually, as part
    of the test flight.
    So, it could have manoeuvred at any time within a 16 day period, and have raised its orbit by 500
    km, perhaps more. Of course, the manoeuvre could have been fairly small, leaving it in more or less
    the above orbit, but on the other side of the planet relative predictions using the old elements.
    Greg is preparing to perform a planar search. Kevin Fetter may also be able to assist, once his
    visibility window opens. As always, there is no guarantee that it will be found quickly, if at all.
    Ted Molczan
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