Greg Roberts has recovered USA 186, last seen on day 13269, which he has observed on three passes over two consecutive evenings, yielding the following orbit: USA 186 258 X 985 km 1 28888U 05042A 13352.82237648 .00025984 00000-0 23965-3 0 08 2 28888 96.9335 49.8482 0519414 203.7413 153.9046 14.81498880 09 Arc 20131217.87-1218.88 WRMS resid 0.014 totl 0.006 xtrk This orbit reveals a manoeuvre to reduce the inclination, which may have occurred early on Nov 12 UTC. The exact date/time are uncertain due to the along-track position uncertainty over the time span involved. Since RAAN was unaffected, the manoeuvre must have occurred at a node. Indeed, the pre and post-manoeuvre orbits were closest at the nodes. The descending node was not far from apogee, so probably was favoured, due to the somewhat lower delta-V requirement. The immediate effect of reducing the inclination has been to precess the orbit westward, out of the primary western KeyHole plane, now solely occupied by the recently launched USA 245. The quasi-97 deg orbit may be a clue that it is intended to eventually manoeuvre the spacecraft into a low, circular orbit like that of USA 161 (shown below). USA 161 389 X 397 km 1 26934U 01044A 13220.08411940 .00013500 00000-0 17063-3 0 00 2 26934 97.0335 351.2744 0005500 40.7551 319.2448 15.59514737 09 Marco Langbroek recently shared his research and ideas on the KH orbits, in which he forecast the westward plane shift and ~390 km, ~97 deg orbit: http://sattrackcam.blogspot.nl/2013/10/past-and-future-of-kh-11-keyholeevolved.html I like Marco's forecast. It will be interesting to see what actually happens. Greg also made new observations of USA 245, which he recovered earlier this month: USA 245 257 X 992 km 1 39232U 13043A 13352.83949499 .00033406 00000-0 30426-3 0 06 2 39232 97.8549 54.5218 0524761 187.5843 171.7207 14.80557970 00 Arc 20131208.83-1218.9 WRMS resid 0.014 totl 0.005 xtrk The larger arc reveals that the perigee height was unaffected by the reboost manoeuvre that pre-dated the recovery. My earlier results indicated an ~14 km perigee-raising, which now seems unlikely. Ted Molczan _______________________________________________ Seesat-l mailing list http://mailman.satobs.org/mailman/listinfo/seesat-l
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