Re: OT: Was this the Project Kevin Fetter Referred to?

From: Björn Gimle (
Date: Tue Dec 11 2012 - 10:21:12 UTC

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    I have followed the elements of Molniyas many times. It IS gravitational
    forces, and possibly SRP, that changes the orbits so that perigee height
    can oscillate by nearly +- 1000 km. The apogees are near the GEO height,
    and the speed there is slower than GEO's.
    If luck runs out, the perigee can become ~100 km, and if sustained long
    enough it will decay.
    OTOH, while drag is active the apogee decreases substantially, reducing the
    perturbations - so some survive in a lower orbit.
    2012/12/7 Brian Weeden <>
    > ...
    An important difference is that for the most part these perturbations do
    > not remove significant energy from the orbit and thus don't lead to it
    > eventually re-entering.  Instead they change and shape the orbit (eg,
    > gravitational pull of the Moon increases inclination of GEO objects).
    > I don't think these forces are what cause Molniya-type objects to decay.
    >  They decay because they have a perigee that is low enough to experience
    > drag effects and that removes energy from the orbit and causes it to
    > eventually re-enter.
    > ------------
    > Brian
    Björn Gimle, COSPAR 5919
    59.2576 N, 18.6172 E, 23 m
    Phone: +46 (0)8 571 43 312
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