Decay Watch: September 24

Alan Pickup (
Fri, 24 Sep 1999 20:21:06 +0100

I have updated my prediction for the decay of #25903, the Foton
12 Soyuz rocket, on my Decay Watch page at

I now put decay more than one orbit later than my estimate yesterday,
but there is still an uncertainty of a couple of orbits. My best guess
at present is for re-entry near a northbound equator crossing at the end
of the orbit given by my predicted elset:

Foton12 Soyuz r  7.4  2.4  0.0  5.5 d   10       134 x 121 km
1 25903U 99048B   99268.10502552  .60337749  32238+1  33235-3 0 90472
2 25903  62.7670 147.5432 0010329 116.7002 243.4055 16.54490678  2473

This would put it over the Indian Ocean, SE of Sri Lanka. However,
earlier in that orbit it passes over SE China (02:38 UTC), S Korea
(02:42), Vladivostok (02:43) and the Bering Sea. It then sweeps SE-wards
over Anchorage, Alaska, at 02:55, NE of Vancouver (03:00), then across
the W USA from Spokane, Washington, at 03:01 to San Antonio, Texas, at
03:07. Perigee occurs in the vicinity of Vancouver, improving the chance
of decay over this stretch of the orbit. The track continues to the
equator W of Ecuador (03:15), across Argentina (~03:25) and the S
Atlantic and far to the S of S Africa before swinging N again over the
Indian Ocean. Decay is still possible on the previous orbit, in which it
crosses the E USA from northern Minnesota at 01:33, over Chicago at
01:35, to S Carolina at 01:38.

I hope to be able to make at least one further update to this page in
the next few hours.

 Alan Pickup | COSPAR 2707:  55d53m48.7s N  3d11m51.2s W   156m asl
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