Björn Gimle wrote: > Yes, Moon/Sun gravitational disturbances generally cause perigee to oscillate > a few hundred kilometers. Occasionally, these cooperate to dip it lower, and > atmosphere starts lowering the apogee. > > This decreases the gravitational disturbances, and there are not enough > forces left to raise the perigee again, and the spiral has begun. Do Molniya keep their special orbit by rocket firings during their lifetime, or are natural forces enough to hold them ? -- Jay Respler -- JRespler@surfnj.net Sky Views: http://njsurf.com/skyviews/ Satellite Tracker * Early Typewriter Collector Freehold, New Jersey