Proposal to re-assign IDs of 2010-062G and X

From: Ted Molczan (ssl3molcz@rogers.com)
Date: Wed Aug 15 2012 - 21:18:42 UTC

  • Next message: joseph daniel: "RE: Is there another Online sat sighting database besides HA ?"

    Since early 2011, we have been tracking several objects from the 2010-062A / 37222 launch, which placed a number of
    small satellites and other hardware into orbit. I have now determined the probable identity of two of the objects that
    had been in doubt. Below are our current ID assignments, and the ones I propose:
    
           Our Current ID                   Proposed ID
    --------------------------  ----------------------------------
    STPSat 2 r 2010-062G 37228  STPSat 2 (USA 217) 2010-062A 37222
    UNID       2010-062X 78701  STPSat 2 r         2010-062G 37228
    
    There were two steps to making these identifications.
    
    1. Optical Characteristics
    
    When the object we have been calling 10062G was discovered, we assigned it to the 4th stage rocket body because it
    seemed too bright to be any of the payloads, most of which are very small. Then we discovered the object we have been
    calling 10062X, which was at least as bright as our 10062G. It was probable that one of the pair was the Minotaur 4
    Stage 4, but which one? Since we were already tracking a Minotaur 4 Stage 4 from another recent launch: 2010-048B /
    37169, I decided to compare the optical characteristics of all three objects, but I needed to wait until a sufficient
    number of observations had been amassed. 
    
    A recent query by Mike McCants prompted me to reopen the analysis. More than a year had passed since I last looked at
    the problem, and there now seemed to be plenty of observations, so I processed them and plotted the usual scatter
    diagram of brightness normalized to 1000 km range vs. phase angle:
    
    http://satobs.org/seesat_ref/misc/2010-062_objects_optical_characteristics.pdf
    
    The three objects have similar standard magnitude, but 10062X and 10048B are much closer in co-efficient of phase (slope
    of the plotted linear regression). Their significantly non-zero values are indicative of somewhat elongated objects.
    10062G's near zero co-efficient of phase suggests a roughly spherical or square box-like shape, typical of most of the
    largest payloads of the 2010-062 launch. This analysis is sufficient to distinguish among the objects, and to recommend
    reassigning 10062X as the real 10062G, but it cannot match our present 10062G to any of the several payloads that it
    might be. Fortunately, orbital analysis can provide the answer.
    
    2. Correlation Between Initial Mean Motion and Payload Deployment Sequence
    
    The deployment sequence described at the following URL is key to identifying 10062G as 10062A:
    
    https://directory.eoportal.org/web/eoportal/satellite-missions/s/stp-s26
    
    Shortly after the launch, accurate official TLEs appeared for objects 10062B, C, D and F. TLEs of A, E and G were not
    issued, but our 10062G and 10062X almost certainly are two of them. Fortunately, there is sufficient orbital data to
    accurately estimate the mean motion near the time of deployment, by propagating the elements. Here they are, in
    ascending order of mean motion, with the real ID and our current ID:
    
          Real ID        Our ID    Initial n
    -------------------  ------   -----------
     Object      Piece   Piece       rev/d
    STPSat 2       A       G      14.76108275
    4th stage      G       X      14.76239043
    FASTRAC        F       F      14.76370494
    FalconSat-5    E       E
    FASTSat        D       D      14.76479367
    O/OREO         C       C      14.76847978
    RAX            B       B      14.77177674
    
    Since 10062A was the only object ejected posigrade, it should have reached the highest orbit, hence the lowest mean
    motion at deployment. The next lowest mean motion should be the 4th stage (G).
    
    Since B through F were deployed retro-grade, their place in the list is in reverse to their place in the sequence, e.g.
    B was deployed first, so was pushed into the lowest orbit. The mean motions agree with the planned sequence described at
    the above URL.
    
    Since our G has the highest orbit (lowest mean motion), it must be the real A object. Since X has the second lowest mean
    motion, it must be the 4th stage, which supports the results of the optical analysis. Neither one could be the E object,
    because their mean motions fall outside the expected range for that object (between that of D and F).
    
    If there is agreement with these findings, then I propose that we make the switch at our earliest convenience. Our
    recent practice has been for Mike McCants to change the IDs of the current TLEs and to alert known active observers of
    that fact, who then update their elements and adopt the new ID when they next observe the object.
    
    Ted Molczan
    
    
    _______________________________________________
    Seesat-l mailing list
    http://mailman.satobs.org/mailman/listinfo/seesat-l
    



    This archive was generated by hypermail 2b29 : Wed Aug 15 2012 - 21:20:03 UTC