More DSP-F23

From: Greg Roberts (grr@telkomsa.net)
Date: Fri Dec 05 2008 - 08:19:45 UTC

  • Next message: Greg Roberts: "Optical 03 Dec 2008 Part 3"

    Morning all
    
    
    The saga of DSP-F23 continues. Lets summarize briefly what the amateur
    network knows:
    
    DSP-F23 did not perform its October 2008 manoeuver. Observations made by the
    amateur network stations that can observe it ( Peter Wakelin in the UK and 
    myself in South Africa) showed that DSP-F23 started drifting in mid-September
    2008.
    
    An undisclosed source reports that radio transmissions failed around this 
    time. During routine monitoring of transmitting classified satellites above
    my location on the 6th Nov 2008 I could find no signals from DSP-F23 on the 
    usual frequencies.
    
    On the 25th Nov 2008 I asked Peter Marsh in the UK - the only other amateur
    station that had access to DSP-F23 and could receive such radio transmission
    -to check my observation of Nov 06,2008. This he did and reported reasonable
    signals. I then checked again on 26th Nov 2008 and found signals on the
    appropiate frequencies which I put down to coming from DSP-F23 but commented
    that they were somewhat weaker then previously. 
    
    News reports now surfacing state that all transmissions ceased in September 
    and the satellite was uncontrolled, so this raises the question as to what 
    Peter and I heard if the satellite was totally dead.
    
    There the matter rested until 03 December 2008 when I found a bright slow
    moving geostationary slowly pass DSP-F23 whilst getting positional observations
    on DSP-F23. I immediately recognised that it was a "new" object as the
    prediction program I was using - HEAVENSAT - had a database of over 12000
    orbital elements and was giving a real time display of objects in the field
    of view. I thus followed the satellite at regular intervals for the next 
    four hours and from this a preliminary orbit was determined.
    
    On the 4th December 2008 I again tracked this new object for another 3 hours
    which will enable an accurate orbit to be determined. At the time of writing
    this the object appears to be very near, if not, geostationary with an 
    inclination of about 6.5 degrees. Like on the 3rd December 2008 it passed
    very close to DSP-F23 - in fact almost occulted it on the 4th December 2008.
    
    Now Peter and I regularly observe this part of the sky and I am sure that we
    would have spotted this object a long time ago if it had been at this location
    for any reasonable length of time.
    
    Now I speculate and play "James Bond":
    
    It is my current belief ( I could be totally wrong!!) that this satellite
    was recently moved from its old position to a new position close to where
    DSP-F23 was stationed. This might explain the signals Peter and I heard on
    the 24/25th November 2008 which we thought were coming from DSP-F23.
    
    Now as to its possible identity. The amateur tracking network knows were all
    the DSP satellites are stationed and has derived recent elements ( less than
    about one month old) for all of them except for DSP-F20 which has not been
    observed for several months and DSP-F22 which is out of range to the amateur
    radio/optical network. DSP-F20 was drifting when last observed and is currently
    visible from the United States area so observations are needed, so this only
    leaves DSP-F22 as a possible DSP candidate. 
    
    I do not believe so for the following reasons:
    
    The new object - for the moment called 91128 - is a lot brighter than DSP-F23.
    When it almost occulted DSP-F23 it was about two magnitudes brighter under the
    same phase-angle conditions. In addition during the 8 hours total that I have 
    observed this object I have seen no typical DSP flashing nor any variation in 
    magnitude other than that due to phase angle variation. I am using integrated 
    images where the satellite is recorded as a trail so its difficult to detect 
    flashing but the traces appear perfectly uniform.  
    
    DSP-F20 had an inclination of 4.08 deg in early 2008 so might be as much as 
    6.5 degrees now (?). It was still in service March 2007 so is the drifting 
    orbit last observed a drift to a new location or that of a graveyard orbit ?
    DSP-F22 has an inclination too low to reach the 6.5 degrees required now to 
    match the new object.
    
    So, at the moment I do not think this is a DSP so how does one explain the
    signals heard on the frequencies used by DSP satellites ?
    
    I do however believe that the object now being observed is almost certainly
    an operational spacecraft - it is far too bright to be a piece of debrii
    and the lack of optical variation would indicate that it is stabilized.
    
    To conclude :  has the saga of DSP-F23 reaches its end yet ?
    
    Maybe all this James Bond speculation will be destroyed if we find that
    91128 is nothing but a drifter than happened to pass DSP-F23 ?
    
    Cheers
    Greg
    
    
    
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