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 <brian.weeden@gmail.com> > ... 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 Mobile: +46 (0) 704 385 486 -------------- next part -------------- An HTML attachment was scrubbed... URL: http://mailman.satobs.org/mailman/private/seesat-l/attachments/20121211/6a8b9e4c/attachment.html _______________________________________________ Seesat-l mailing list http://mailman.satobs.org/mailman/listinfo/seesat-l
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