Description of 2-line elements: http://www.satobs.org/element.html USA 129 15.0 3.0 0.0 5.3 v 1 24680U 96072A 04159.21231845 .00007272 00000-0 99313-4 0 09 2 24680 98.0248 220.1551 0521364 287.5470 66.9437 14.73885128 05 Arc 2004 Jun 01.18 - 07.22, WRMS residuals = 0.023 deg The recent decline in this object's rate of decay is attributable to three factors: 1. Perigee has precessed into Earth's shadow. Atmospheric density is lower in shadow than in sunlight. 2. Perigee has precessed to mid-Northern latitudes, where perigee-distance is greatest, due to the odd zonal harmonics of Earth's gravitational field. Atmospheric density decreases with altitude. 3. Solar flux has declined. Conditions at perigee are important for objects in significantly eccentric orbits, like USA 129, because most decay occurs near perigee. Ted Molczan ------------------------------------------------------------------------- Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive: http://www.satobs.org/seesat/seesatindex.html
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