Re: Geosynchronous satellites congregate?

From: Chris Jones (clj@panix.com)
Date: Sun Jun 11 2006 - 17:58:01 EDT

  • Next message: Steve Walter: "Re: Geosynchronous satellites congregate?"

    Tom Wagner wrote:
    
    > As an experiment I tried stepping ahead in time a day at a time. What I 
    > saw was very peculiar. Within a year or two a lot of the satellites that 
    > I saw generally south of my position of 92 degrees W longitude began to 
    > congregate directly south of me. Is this a phenomenon that would occur 
    > if the satellites did not compensate via onboard propellant?
    
    The concept of a geostationary orbit is an ideal solution of the two body
    problem for spherical bodies of uniform density (which can be modeled as
    points).  In the real world, err, solar system, the earth is not spherical
    exactly (nor is it exactly an oblate sphere; it's very very slightly pear-
    shaped).  Thus, there are a couple of longitudes (whose values, unfortunately,
    I can't quickly lay why hands upon) toward which satellites at geosync
    altitude are attracted.  They actually would tend to oscillate back and forth
    past these points, I am told, rather than congregate.
    
    Also, satellites' motions are perturbed by more than just the earth's gravity.
    Every other body in the universe exerts some effect, though probably only
    those of the moon's and sun's gravitational fields are very noticeable.
    
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