Decay watch: May 15 (Final orbits of Iridium 70 Delta 2)

Alan Pickup (alan@wingar.demon.co.uk)
Sat, 15 May 1999 11:49:52 +0100

Apparent connectivity problems between my ISP and OIG's server are 
preventing me from updating the SpaceCom prediction for the decay of 
the Iridium 70 Delta 2 rocket. However, I have obtained updated elsets 
via another route...
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Object: #25347 = 98- 32 F = Iridium 70 Delta 2 r

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

SpaceCom   May 11 17:34     May 15 18:01 +-2d        18.5 S   124.9 E
SpaceCom   May 12 19:49     May 15 18:13 +-2d        60.8 S   163.8 E
SpaceCom   May 13 13:36     May 15 13:25 +-9h        19.8 S    69.2 E
SpaceCom   May 14 15:01     May 15 15:25 +-15h       26.7 S   146.2 W

SatEvo     May  9 14:25     May 15 18:00 +-1.5d
SatEvo     May 12 18:20     May 15 17:42 +-15h
SatEvo     May 13 19:20     May 15 11:41 +-9h        30.0 N    88.7 E
SatEvo     May 14 18:50     May 15 11:49 +-5h         0.0      90.1 E
SatEvo     May 15 10:30     May 15 14:05 +-2h        16.1 N   122.4 W

Latest elset:
Iridm 70 Delta r 5.9  2.4  0.0  5.6 d            168 x 160 km
1 25347U 98032F   99135.28000050  .09277033 -16217-5  69828-3 0  4721
2 25347  84.0964 320.2747 0006391  26.5718 333.6003 16.40642020 56236

SatEvo prediction:
Iridm 70 Delta r 5.9  2.4  0.0  5.6 d            159 x 152 km
1 25347U 98032F   99135.40185343  .15761747  23824+0  59605-3 0 94727
2 25347  84.0953 320.1602 0005323  26.0449 333.9818 16.43846996 56253
Iridm 70 Delta r 5.9  2.4  0.0  5.6 d            153 x 147 km
1 25347U 98032F   99135.46269100  .22071940  52866+0  53532-3 0 94725
2 25347  84.0946 320.1029 0004595  25.7809 334.2420 16.46097201 56268
Iridm 70 Delta r 5.9  2.4  0.0  5.6 d            143 x 138 km
1 25347U 98032F   99135.52342568  .39741758  18594+1  51918-3 0 94728
2 25347  84.0935 320.0454 0003538  25.5162 334.5012 16.49630146 56278

Note: The current elset has it 31 seconds late on yesterday's 
prediction, suggesting that SpaceCom's (and Harro's) later decay times 
have been nearer the mark. I now calculate decay following a northbound
equator crossing over the W Pacific on a track that would reach San 
Francisco at 14:10 UTC. It could still survive for another orbit.
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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
 Scotland    | SatEvo page:     http://www.wingar.demon.co.uk/satevo/