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Old October 10th 04, 09:17 AM
AA Institute
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"Grimble Gromble" wrote in message news:pWV9d.425
Are you familiar with this equation (quoted by Henry Spencer on
sci.space.tech a while back):-
An Earth circling satellite orbit will precess along the equator over
time according to the equation:-
-3/2 * J2 * (R^2 / p^2) * n * cos (i)
[Where J2 is a constant related to Earth's flattening, R is the
Earth's eq. Radius, p = a*(1-e^2) (in which a is the orbit's
semi-major axis and e is its eccentricity), n is the mean motion and i
is the orbit's inclination.]

Being familiar with an equation is not the same as understanding it. That
the earth's flattening is involved suggests that this precession is caused
by tidal influences experienced by the satellite as it orbits above and
below the earth's equatorial plane. That there is no term relating to the
lunar and stellar masses, suggests that this is a very simplified analysis
in which all other influences have been ignored. Is there any reason you
introduce this (idealised particulate) satellite into a discussion on earth
rings? Perhaps you are comparing the effect on an orbiting satellite of the
earth's equatorial bulge to that of an independently orbiting ring? You do
realise that there are significant electromagnetic forces operating between
the 'equatorial' bulge and the 'spherical' earth?


Since each discrete particle in a ring system, such as the one I
envision here, is effectively a *satellite* in its own right, and the
individual particles are orbiting the Earth at appreciably different
distances (the ring has some *width*), the above equation - along with
another similar equation - can be used to show that under certain
favourable orientations of a ring system the particles are unlikely to
scatter significantly.

Probably doesn't make too much sense here... I am working on a short
paper to better illustrate this, which I hope to make available when I
get some spare time.

Abdul