X-37B OTV 1-1 search elements

From: Ted Molczan (ssl3molcz@rogers.com)
Date: Mon Oct 11 2010 - 00:52:22 UTC

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    As reported at the URL below, consecutive reported no-shows strongly suggest that OTV 1-1 has
    manoeuvred:
    
    http://satobs.org/seesat/Oct-2010/0084.html
    
    My search strategy consists of the following, in order of priority:
    
    1. Check last known orbit
    
    The two no-shows could have been because the object was unusually faint; therefore, it would be
    worth making at least one more attempt to spot it within a minute or two of the last known orbit:
    
    X-37B OTV 1-1                                            433 X 444 km
    1 36514U 10015A   10278.73792454  .00000561  00000-0  12188-4 0    04
    2 36514  39.9880  62.1228 0007830 334.9144  25.1283 15.43395766    05
    Arc 20101001.77-1005.78 WRMS resid 0.025 totl 0.004 xtrk
    
    
    2. Planar search of last known orbit
    
    If the manoeuvre was small, then the resulting orbit would not be much different than the last
    known, in which case a planar search of the above orbit would reveal it. Using wide-field optics, or
    scanning at least 5 deg either side of track, would be sufficient for altitude changes of a few tens
    of kilometres, especially at low elevation above the horizon. That is how Greg Roberts found it
    after it manoeuvred in August to raise its orbit by 27 km.
    
    
    3. Assume it returned to its previous orbit
    
    One of my guesses is that it manoeuvred to return to its previous orbit. Within the 1.7 d period in
    which the change must have occurred, it appears that consecutive burns on Oct 06 near 13:13 UTC and
    13:55 UTC, would have enabled the best coverage by AFSCN ground stations. In the highly unlikely
    event that all of my guesses are correct, then it might be found within 10 to 20 min of this orbit:
    
                                                             403 X 420 km
    1 70001U          10279.58017362  .00000000  00000-0  00000-0 0    02
    2 70001  39.9880  57.0131 0012520 161.3595 205.2000 15.52630000    05
    
    Note that with a reasonably wide FOV, this orbit would also be covered by Option 2.
    
    
    4. Manoeuvre to set up a daily repeating ground track
    
    Daily repeating ground tracks have been used for military surveillance, but seldom by the U.S.A., so
    this is very speculative. My guess is that the burns would have occurred at about the same times as
    in Option 3, but would have resulted in a higher orbit.
    
                                                             481 X 498 km
    1 70002U          10279.57465279  .00000000  00000-0  00000-0 0    06
    2 70002  39.9880  57.0496 0012384 161.3134 173.0000 15.26250000    08
    
    This one may not be covered by a wide FOV search of the existing orbit, requiring a separate planar
    search.
    
    Of course, there are many other possibilities. The spacecraft reportedly can reach 900 km altitude,
    and it could also change inclination.
    
    Happy hunting!
    Ted Molczan
    
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