RE: sat decay

From: Matson, Robert (ROBERT.D.MATSON@saic.com)
Date: Thu Jan 31 2002 - 10:06:48 EST

  • Next message: Alan Pickup: "Decay watch: EUVE decay"

    Hi All,
    
    In reply to my earlier statement:
    
    > The 90-degree inclination case simply reduced to the global
    > land-to-water ratio.
    
    Aaron Brown wrote:
    
    > I don't think this is true.  The surface near the poles would
    > be weighted much more heavily.  Imagine if the only land was
    > between 80 and 90 degrees latitude.  The global land/water
    > ratio would be far less than 10/180, yet the satellite would
    > be over land 10/180 of the time.
    
    Aaron is absolutely correct -- my apologies.  I completely
    neglected the cosine effect with latitude.  This actually
    makes the land/water ratio vs. orbital inclination function
    an even more interesting calculation.  The only hard part of
    solving this problem is creating a function which when given
    a specific latitude and longitude returns "water" or "land".
    Or taking it one step further, returns a geographic label
    (e.g. country name, ocean, sea, island, etc.)  This function,
    in conjuction with a specific decaying orbit, could then be
    used to assess impact probabilities in an automated fashion.
    
    With a little more complexity (taking orbital height, day/night,
    and minimum elevation angle into consideration), the function
    could be expanded to assess the chances of observing the
    reentry from a given location.
    
    Best,
    Rob
    
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