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USA 179

Tyneside, UK
2018 Jan 20
Saturday, Day 20

Maintained by:

USA-179 Analysis:

USA 179 - Orbit

The map shows the sub-satellite ground track at 2006 November 17. USA 179 itself is above Italy at an altitude of 81,884 kilometres, close to the morning day/night terminator. The plot is based on this element set from Mike McCants's "classified.tle" file:
1 90027U 04841A   06322.78169364 0.00001111  00000-0  63148-0 0    01
2 90027  62.6062 128.2394 7033831 269.3293  90.6707  2.00608772    01
It describes an orbit of 1,499 x 38,858 kilometres at 62°.6 inclination with an anomalistic period of 717.80 minutes. It follows the patch shown on the map and repeats roughly the same track from day to day

The map was produced using "Orbitron" by Sebastian Stoff

The shape of the ground track plot is produced by a combination of USA 179's motion around its orbit and the rotation of the Earth. The symmetry is driven by the fact that the argument of perigee is very close to 270° which puts apogee at northern apex.

There is almost zero atmospheric drag on a satellite in an orbit like the one occupied by USA 179. However, there are gravitational influences that pull it away from its elliptical shape and pull it out of position. They come from the Sun, the Moon and the fact that the Earth itself is not a uniform shape.

Because of these influences, controllers find it necessary to correct the orbit every 20 days or so in order to keep things as they want them. The year pages listed in the left hand menu tell the story from mid-2006.
Copyright © Robert Christy, all rights reserved
Reproduction in whole or in part without permission is prohibited