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

From: satrack@libero.it
Date: Fri Nov 11 2011 - 19:55:19 UTC

  • Next message: satrack@libero.it: "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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