Re: observations of Phobos-Soil (Fregat) engine burn

From: ronlee@pcisys.net
Date: Wed Nov 02 2011 - 18:30:30 UTC

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    Apparently I used 7x50 binoculars.  Here is the report:
    
    http://www.satobs.org/seesat/Jul-1999/0124.html
    
    GLOBALSTAR MO32                                  1378 x 1351 km
    1 25851U 99037A   99191.43302173 -.00000107  00000-0  00000-0 0    14
    2 25851  52.0103 315.9533 0017926 245.9263 114.0701 12.74308640    08
    
    This is very close to the prelaunch elset provided.
    
    The Delta second stage was observed in binoculars just after 10:32 UT
    on 10 Jul 99.   As it rose in elevation , I could see one fainter 
    object on either side of the second stage.  If the direction of motion
    is 12 o'clock, right from the satellite is 3 o'clock (southeast or to
    the lower left from my perspective). then the two sets of Globalstars
    were at about 2 and 8 o'clock.    Since the objects were moving from
    the SSW to NE, they appeared almost parallel to the horizon from my
    vantage point.
    
    At 10:33:56 UT I noticed the burn.  The burn was oriented to the NW
    or about 10 o'clock from the clock positioning I described.  It was not
    very impressive.  However, at about 10:34:30 UT I did notice a definite
    separation of the second stage to the SE away from the satellites.
    
    Times are plus or minus a second or so since I transcribed the times from
    a tape recorder.  Several sources of error since I was not concerned
    with absolute time accuracy.
    
    After closing the shutter on the camera, I was unable to reacquire
    the satellites. No problem.  I had wisely (for a change), created 
    a second Skymap chart showing the depletion burn region.  After
    finding the appropriate stars, I waited.  On time at 10:41:27 UT
    the depletion burn started.  This one was AWESOME.  Soon after the
    burn started, I made a note that it was turning.  I believe the initial
    plume direction was to the NE from my perspective or about 1 o'clock
    from its direction of motion perspective.
    
    At 10:41:56 UT it went between two target stars and I observed the
    plume easily with the naked eye. The size was not measured accurately
    but was perhaps two-three degrees in length.  At 10:42:25 UT, the 
    outgassing from the rocket was still visible although the main plume 
    was now very faint.  At 10:42:49 UT the outgassing continues and by
    10:43:10 UT I felt it was over.
    
    During the time, my impression is that it corkscrewed perhaps one full
    turn.   I suspect that the main plume was caused by the actual burn 
    scheduled to last for seven seconds and that the remainder of the 
    outgassing I saw was residual propellant/pressurant dumping.
    
    The elset I have show that the satellites were above (trajectory wise)
    the second stage during the depletion burn.  The burn orientation would
    have been away from the satellite and in a direction to lower the
    perigee.
    
    I am curious if the poor showing of the evasive burn was because it 
    was to the south (sun rising in the NE) while the depletion burn 
    was "over" the rising sun?
    
    This would have been a great event to videotape.  Does anyone here
    have details on a suitable videocamera that would record under these
    conditions?
    
    Ron Lee
    
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