Re: Geosynchronous satellites congregate?

From: Tony Beresford (dberesford@adam.com.au)
Date: Mon Jun 12 2006 - 07:15:30 EDT

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    At 06:27 12/06/06, Tom Wagner wrote:
    >I am using my planetarium program to see if the orbital altitude of the geosynchronous satellites listed in the program match with what I saw on the Net was the appropriate distance for them to have a 24 hour orbital period. I compared their distances with calculations made at this site http://liftoff.msfc.nasa.gov/academy/rocket_sci/orbmech/vel_calc.html and get a close match. Does the orbital period need to be exactly 24 hours?
    
    24 hours of sidereal time or approximately 23 hours 56min 4 seconds Mean solar time.
    The Objects you referred to should be described as geostationary , a stricter condition than
    geosynchronous. To be geostationary the inclination has to be very small. Some comsats whose target markets with
    relatively wide beam antennae can allow the inclination to go up to 3-4 degrees.
    
    
    
    
    
    >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?
    
    I suspect this is a computational artifact. The SPDP orbital model is an engineering solution for the monitoring
    of geostationary and near geo satellites. It wasnt meant to handle year long predictions.
    
    Tony Beresford
    
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