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USA 179

Tyneside, UK
2018 Apr 21
Saturday, Day 111

Maintained by:

USA-179 Analysis:

Orbital Adjustments in the First Half of 2008

The major orbital adjustment that would have been the norm in early-January did not happen in the same way as in the past. When the Mean Motion hit its peak value, the downward adjustment was quite small and the Mean Motion kept increasing. The major manoeuvre occurred late on Feb 8.

At this point, USA 179 set three "personal" records since it became operational - the highest value of its Mean Motion ever measured, followed by the biggest drop, and then the lowest value ever measured. The ground track is now somewhat to the east of the earlier operational location. The orbit is in view from the UK when USA 179 is following the Pacific loop of its trajectory. Transmitter switching in now visble across the north pole where it used to occur below the horizon.

The new location maintains ground-track synchronisation with USA 137 and USA 198, the newcomer to the constellation. Prior to the recent launch, USA 179's operating companions were USA 137 and USA 125.

2008 February saw two significant retrograde adjustments. One came soon after the Feb 8 major adjustment - interpreted as a small tweak to correct a small error. The second came Feb 28 but the reason is not obvious.

In 2009 March, this type of observation became obsolete. USA 198 completed its testing and joined USA 179 in a duty-sharing arrangement. Timings were no longer driven by the orbital elements of a single satellite.

USA 179 2008
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