R: RE: Phobos-Grunt: latest two TLEs suggest manoeuvring or venting

From: satrack@libero.it
Date: Fri Nov 11 2011 - 20:00:26 UTC

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    ...sorry I typed the Norad of the r/b instead of that of the spacecraft...
    
    Simone
    
    >----Messaggio originale----
    >Da: satrack@libero.it
    >Data: 11-nov-2011 20.55
    >A: <ssl3molcz@rogers.com>, <seesat-l@satobs.org>
    >Ogg: R: RE: Phobos-Grunt: latest two TLEs suggest manoeuvring or venting
    >
    >Am I wrong or with the new TLE (11315.4526) the spacecraft position is 
    changed?
    >
    >Regards,
    >Simone
    >
    >>----Messaggio originale----
    >>Da: ssl3molcz@rogers.com
    >>Data: 11-nov-2011 17.38
    >>A: <seesat-l@satobs.org>
    >>Ogg: RE: Phobos-Grunt: latest two TLEs suggest manoeuvring or venting
    >>
    >>While waiting for new TLEs of the s/c, I have been taking a closer look at 
    >the two that indicate an orbit change.
    >>Interestingly, both nearly intersect with the pre-orbit change TLE at about 
    >the time of a pass within range of Baikonur,
    >>on Nov 10 from ~20:16 to 20:23 UTC. 
    >>
    >>Probably, this will turn out to be a meaningless coincidence, but it does 
    >seem interesting in view of efforts to
    >>communicate with the s/c from that site, so I am putting this out with the 
    >caveat that I have been burned lots of times
    >>by spurious TLEs and various coincidences that later proved meaningless. 
    >Subsequent TLEs could make this all go poof!
    >>
    >>Below are the circumstances of the pass. I don't know the coordinates of 
    the 
    >telemetry transmitter, so for now, I used
    >>those of the Zenit pad used for the launch:
    >>
    >>  UTC
    >>20:15:54 rose above 0 deg elevation
    >>20:16:17 reached 2 deg
    >>20:19:36 culminated at ~30 deg
    >>20:23:06 set below 2 deg
    >>20:23:31 set below 0 deg
    >>
    >>Closest approach between pre-orbit change TLE and first post-change TLE is 
    >~20:15:52 UTC. Relative the second
    >>post-change TLE, it is ~20:13:36 UTC. Due to the low delta-V, these times 
    are 
    >not well-defined, and uncertainty is at
    >>least several minutes.
    >>
    >>If there was a single impulse at the point of intersection, then delta-V  
    was 
    >1.3 to 1.6 m/s (4 to 5 fps).
    >>
    >>Ted Molczan
    >>
    >>
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    >
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