> Is there is an effect due to the Earth's equatorial bulge? When the > satellite is at the extremes of its angular track does the bulge pull it > into more of an equatorial orbit? Obviously this will be a very small effect > because the earth is almost spherical - but is it significant for LEOs? The largest effect of the bulge constantly pulling towards the equator plane is the precession of nodes: A satellite will have its next equator crossing less than 180 degrees from the previous (disregarding Earth's rotation), ie. with inclination < 90 degrees the nodes will precess west, > 90 degrees they will precess east. The effect is largest for a LEO with a low inclination, but measured cross-track it is largest for i=45 deg. ISS 20.0 4.0 0.0 2.5 d 70 342 x 333 km 1 25544U 98067A 00131.47902778 .00059387 00000-0 34950-3 0 6284 2 25544 51.5844 331.8932 0006529 167.2015 212.0047 15.77600877 84019 ISS 20.0 4.0 0.0 2.5 d 70 341 x 332 km 1 25544U 98067A 00134.16383102 .00070901 00000-0 40876-3 0 6387 2 25544 51.5842 318.0107 0006443 178.7508 340.7746 15.77992122 84435 (331.8932-318.0107)/2.3152 days =5.9962 deg/day; or about 550 km cross-track per day! -- bjorn.gimle@tietotech.se (office) -- -- b_gimle@algonet.se (home) http://www.algonet.se/~b_gimle -- -- COSPAR 5919, MALMA, 59.2615 N, 18.6206 E, 33 m -- -- COSPAR 5918, HAMMARBY, 59.2985 N, 18.1045 E, 44 m -- -- SeeSat-L / Visual Satellite Observer Home Page found at -- -- http://www2.satellite.eu.org/satintro.html -- ----------------------------------------------------------------- Unsubscribe from SeeSat-L by sending a message with 'unsubscribe' in the SUBJECT to SeeSat-L-request@lists.satellite.eu.org http://www2.satellite.eu.org/seesat/seesatindex.html
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