Re: Goes 11 retired from service

From: Leo Barhorst (l.barhorst@upcmail.nl)
Date: Thu Dec 08 2011 - 17:50:52 UTC

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    Hello,
    
    Another reason not to choose a lower orbit is that
    all the new geosats then have to pass through the graveyardbelt
    with all those uncontrolled satellites.
    
    Satellites in a higher orbit can eventally come down to the geo orbit again.
    But by then their orbital inclination has become much greater up to 15-20 
    degrees.
    So they then only cross the geo orbit for short periods twice a day.
    
    Greetings
    Leo Barhorst
    
    -----Oorspronkelijk bericht----- 
    From: Dale Ireland
    Sent: Thursday, December 08, 2011 12:41 AM
    To: seesat-l@satobs.org
    Subject: RE: Goes 11 retired from service
    
    
    Thanks Robert
    That is just what I was wondering about. If the Moon or Sun tend to raise
    the orbits at that distance. I guess that anyone who follows the regular
    orbit adjustments for the active satellites might know if they are usually
    raised or lowered. That may be an over-simplification.
    Dale
    
    > -----Original Message-----
    > From: seesat-l-bounces+direland=drdale.com@satobs.org
    > [mailto:seesat-l-bounces+direland=drdale.com@satobs.org] On
    > Behalf Of Robert Fenske Jr
    > Sent: Wednesday, December 07, 2011 3:02 PM
    > To: seesat-l@satobs.org
    > Subject: RE: Goes 11 retired from service
    >
    >
    > The geosynchronous orbits are high enough that atmospheric
    > drag isn't a factor.
    > Only the lunar and solar perturbations are and they must
    > simply be not enough to move a satellite into the operation
    > orbit range.  Or perhaps at that distance the perturbations
    > have a tendency to move the satellite even further away from
    > the Earth.
    >
    > I don't know why a higher orbit is chosen vs a lower one.
    > Since the manuevers are done at the end of life -- when there
    > is little fuel remaining -- often it is chancy whether the
    > push to the graveyard orbit can be done.  It may be that a
    > push to a high orbit takes less energy and so is more likely
    > to succeed.
    >
    > Robert Fenske, Jr
    >
    > On Wed, 7 Dec 2011, Dale Ireland wrote:
    >
    > > Why is the "graveyard" 135 miles higher than the active
    > satellites? If
    > > the satellite becomes totally unoperational won't it
    > eventually drop,
    > > possibly uncontrolled, back down through the geo belt? Why wouldn't
    > > they make the graveyard 135 miles lower than the belt rather than
    > > higher? Are there other forces involved?
    > > Dale
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