Hi Satelliters, Using Keps from Space-Track for ARISSat-1 (37772) I have been plotting various parameters including Mean Motion. Rrecent results were unexpected. >From day 328to 334 the daily change in Mean Motion has been exactly the same. The orbital decay is going at a very steady rate. This is completely different from earlier observations where there is quite a bit of daily variation. My interpretation is that the atmospheric density along the orbital track has been remarkably unchanged over 6 days or so. This is something I have not seen before. 73 John G7HIA _______________________________________________ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb