RE: Orbital surveillance satellites now exceed 1 inch resolution?

From: Ted Molczan (molczanssl@rogers.com)
Date: Tue May 01 2007 - 22:13:59 EDT

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    Robert Clark asked:
    
    > My reading of the discussion on the "Misty" type satellites 
    > suggests they are difficult to track visually.
    > So how are these orbital elements so accurately determined 
    > to the degree that the amount of orbital decay they are 
    > experiencing can be determined?
    
    The object in question is readily tracked because is not a Misty satellite. It
    is either debris or a decoy resulting from the launch of what is now believed to
    be Misty 2 (1999-028A / 25744), which was launched in May 1999.
    
    In June 1999, hobbyists began tracking an object from that launch that was
    fairly intrinsically bright, in a 63.4 deg, 2700 km x 3100 km orbit, which
    seemed like it might be the payload. Initial speculation was that it was an
    IMINT satellite of KH-11 lineage, sent into a higher than usual orbit, to obtain
    increased dwell-time and wider area coverage of targets, at reduced resolution -
    a need that had been identified as a result of experience during Operation
    Desert Storm. 
    
    This theory began to fall apart in 2002, with the discovery of the object's high
    area-to-mass ratio, which makes it more likely to be debris than a payload, as I
    reported in the following post, which I believe you have read:
    
    http://satobs.org/seesat/Aug-2002/0045.html
    
    In the above post, I also discussed the object's other debris-like
    characteristic: it rotates, unlike most payloads, which are 3-axis stabilized.
    
    Initially, its period of brightness variation was about 150 s, which had
    decreased to 116 s after three years. By the summer of 2005, it had decreased
    below 80 s; since then it appears to have been increasing:
    
    http://satobs.org/seesat_ref/99028C_period_of_var/99028C_period_of_var_3.jpg
    
    If the object were a spin-stabilized payload, then I would expect its rate of
    rotation to remain much more nearly constant.
    
    In late 2005, we changed our designation of the high object from 1999-028A /
    25744 to 1999-028C / 25746, in recognition that it could not be the primary
    payload, and most likely is debris, or a decoy, intended to draw attention away
    from Misty 2, which most likely would have gone to a quasi 65 deg, 700 - 800 km
    orbit, like that of its predecessor.
    
    We should have made the switch sooner, but finally acted when it became clear
    that using the original ID was creating confusion among those not familiar with
    the evolution of our understanding of this object.
    
    Based on its observed brightness, 99028C probably has a cross-sectional area of
    about 50 m^2. Assuming it presents an equivalent area to the sun, then its mass
    is about 560 kg, based on its area-to-mass ratio of about 0.09 m^2/kg, derived
    from analysis of solar radiation pressure perturbations.
    
    For the object to be a primary Titan IV-B class payload, it would have to be
    very massive, and have a large surface area facing the sun, to account for its
    area-to-mass ratio.
    
    I estimate that a manoeuvrable Titan IV-B payload in excess of 10,000 kg (dry
    mass) could reach the 63.4 deg, 2700 km x 3100 km orbit of 99028C, which would
    require a sun-facing surface area of about 900 m^2. I cannot imagine an NRO
    spacecraft so-configured.
    
    The JWST (James Webb Space Telescope), has a mass of 6200 kg, and a sunshield of
    220 m^2, resulting in a sun-facing A/m of 0.035 m^2/kg, well short of 99028C's
    value. Of course, unlike NRO telescopes, JWST is designed for ultra-high IR
    sensitivity, requiring it to have the large sunshield. Also, JWST is 3-axis
    stabilized.
    
    Ted Molczan
    
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