Bjoern Gimle wrote: >>James E. Byrd wrote: >>Mir ... repeat it's ground track every 7 days 20 hrs 52 minutes. >> >Ted Molczan wrote: >>I find the following groundtrack repetition frequencies: >> >>Epoch 46 revs 123 revs >>96185 2d 23h 57m 8d 00h 24m >>96270 2d 23h 48m 8d 00h 01m >> >I don't quite see what you mean with a ground track repetition >period of a near integer number of days. > >To me, that is something that only occurs for sun-synchronous >and almost geostationary satellites (and periods larger than >about 40 days for low-inclination orbits, that have moved their >ascending node once around the Earth-Sun line). I was in error. I should have expressed it like this: 3 day resonance 8 day resonance Epoch revs period revs period 96185 46.0303 2d 22h 49m 122.7474 7d 20h 51m 96270 46.1203 2d 22h 48m 122.9875 7d 20h 50m The orbit is exactly resonant when it makes an integer number of revolutions in the specified time. The 3 day resonance is referring to an integer number of days, but the period of 2d 22h 49m is the exact time separating the start of the repeating track. My conclusion remains the same: The three day repetition has deteriorated slightly; the 8 day repetition has improved somewhat. Ted Molczan