Re: Decay watch: February 21

Alan Pickup (alan@wingar.demon.co.uk)
Sun, 21 Feb 1999 23:34:41 +0000

The SatEvo decay list I posted earlier today was, of course, issued
on February 21 and not 20 as stated - apologies.

The final(?) word on the Soyuz rocket:
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Object: #25633 = 99- 7 B = Soyuz TM-29 Soyuz r

Decay predictions:
Source   Prediction made    Predicted decay at      Latitude Longitude
               UTC                UTC                  deg      deg

SpaceCom   Feb 20 13:48     Feb 21 20:54 +-19h       50.8 S    35.6 E
SpaceCom   Feb 20 19:52     Feb 21 19:01 +-14h        3.8 N    43.4 W
SpaceCom   Feb 21 06:57     Feb 21 18:35 +-8h        46.7 N   156.8 W
SpaceCom   Feb 21 12:13     Feb 21 18:05 +-4h        40.3 S   112.0 E
SpaceCom   Feb 21 16:08     Feb 21 18:04 +-1h        42.7 S   107.5 E
SpaceCom   Feb 21 18:21     Feb 21 18:04 +-28m       42.4 S   108.0 E

SatEvo     Feb 20 13:55     Feb 21 16:03 +-9h         0         3.7 E
SatEvo     Feb 21 10:00     Feb 21 16:03 +-4h         0         3.7 E
SatEvo     Feb 21 19:35     Feb 21 16:47 +-1h         0       172.6 E

Final elset:
Soyuz TM-29 Soyuz r                              147 x 141 km
1 25633U 99007B   99052.63890138  .20865573  12602-4  32101-3 0   157
2 25633  51.6404 215.9489 0004503 111.8831 248.2713 16.48276255   243

Note: The last elset shows it running 8 seconds late on my final
prediction which was based on elsets issued more than 19 hours before.
The published elset for the preceding orbit had it only 0.5 seconds
late, so SatEvo had been performing very well until that point. The
indication is that the drag increased less than expected near the end,
another indication that SatEvo must still be improved to handle the
transition in atmospheric flow regime which the rocket could have
encountered about that time. A fit through the final elsets leads to
decay near a northbound equator crossing over the Pacific. If it had
survived this, as SpaceCom says it did, then it would have overflown the
length of southern Canada on the next orbit and I would have expected a
corresponding elset. I waited, but none has appeared (yet).
---------------------------------------------------------------------

Alan
-- 
 Alan Pickup | COSPAR 2707:   55d53m48.7s N   3d11m51.2s W   156m asl
 Edinburgh   | Home:   alan@wingar.demon.co.uk    +44 (0)131 477 9144
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