Re: R: [amsat-bb] Re: AO40 orbit drifting south, then north?

["Stacey E. Mills" <w4sm@xxxxxxxxxx>]

At 05:27 AM 2002-03-27 +0100,  I8CVS wrote:


>Hi  Stacey,
>
>The greater the inclination, the more the variability is not completely
>correct.
>If the inclination ( i ) is 63.34 degrees the line of the apsis  that
>join the apogee with perigee do not rotate at all and so the rate of
>change of the argument of perigee ( W ) is zero degrees and the satellite
>subpoint SSP at apogee stay constant for ever.

[snip]


>If the inclination is less than 63.34 degrees the line of the apsis rotate
>in the same direction of the satellite motion along the orbit

[snip]

>If the inclination is greater than 63.34 degrees the line of the apsis
>rotate in a direction wich is opposite to the satellite motion

[snip]

What you say is absolutely correct, well, except for the "forever".  That's 
a very long time.  The fixation of ArgP precession at inclination = 63.34 
degs is the definition of a Molniya orbit and what we were aiming for with 
AO-40.  However, I think you missed my point.  The discussion was about 
variation in subsatellite latitude.  I did not say that the higher the 
inclination the more (rate of) variation in ArgP.  This is, of course, not 
true.  As you have indicated, the rate of change in ArgP decreases as 
inclination increases towards 63.34 degs.  Above that, change in ArgP 
begins increasing in the opposite direction.   My point was that the higher 
the inclination the more variability in SUBSATELLITE LATITUDE as ArgP 
changes.  Hence my reference to AO-13's much larger apogee shifts above and 
below the equator.  The rate of change of ArgP was much lower for AO-13 
because of the higher inclination, but that wasn't my point.  I was only 
discussing the amount of variation in subsatellite latitude.

I hope this clarifies things.




-- 
  _______________________________________________________________________
  Stacey E. Mills, W4SM    WWW:    http://www.cstone.net/~w4sm/ham1.html
   Charlottesville, VA     PGP key: http://www.cstone.net/~w4sm/key
  _______________________________________________________________________

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