Re: Satelite eccentricity


"Steve Willner" <willner@xxxxxxxxxxxxxxx> wrote in message
news:44c7d581$1@xxxxxxxxxxxxxxxxxxxxxxxxxx
In article <44c52f10$1@xxxxxxxxxxxxxxxxxxxxxxx>, I agreed with George
Dishman, who wrote (in article <e9odpp$dds$1@xxxxxxxxxxxxxxxxxxxxx>):
If the [nearer tidal] bulge is ahead
that would accelerate the satellite, as Earth does to
the Moon, hence by your argument tending to reduce the
eccentricity.

On thinking about this some more, I'm confused. Yes, the nearer
tidal bulge accelerates the satellite, but the acceleration is
greatest at perigee. Acceleration at perigee tends to raise the
_apogee_ and thus increase the eccentricity.

There's probably something wrong with the way I'm thinking about this
problem, but I don't see what it is.

I see the problem, thanks for correcting that Steve.
I was wondering if we could measure the rate of
change of the Moon's eccentricity by LLR and found
this:

http://dda.harvard.edu/brouwer_award/BrouwerAward_2006_Williams.pdf

which discusses eccentricity rate on page 25. The
value of 1.3*10^-11 per year appears to indicate
the eccentricity increases due to Earth tides
though at a very low rate.

George



.

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