Decay watch: July 1 (Titan down)

Alan Pickup (alan@wingar.demon.co.uk)
Thu, 1 Jul 1999 23:58:42 +0100

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Object: #25670 = 99- 17 B = DSP 19 Titan 4 r

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

SpaceCom   Jun 27 10:54     Jul  1 10:37 +-19h       22.2 S   171.6 W
SpaceCom   Jun 28 17:18     Jul  1 15:31 +-2d         4.7 S   123.7 W
SpaceCom   Jun 29 17:47     Jul  1 17:19 +-1d        26.9 N    74.6 W
SpaceCom   Jun 30 18:51     Jul  1 19:09 +-21h        9.2 N     8.0 W
SpaceCom   Jul  1 07:58     Jul  1 19:59 +-8h         2.5 N   178.8 W
SpaceCom   Jul  1 13:23     Jul  1 19:23 +-2h        16.3 S    38.2 E
SpaceCom   Jul  1 17:37     Jul  1 19:42 +-29m       25.2 S   121.9 E
SpaceCom   Jul  1 21:59     Jul  1 19:55 +-1m         5.1 S   168.1 E

SatEvo     Jun 27 18:50     Jul  2 09:07 +-1d
SatEvo     Jun 28 19:45     Jul  2 04:38 +-16h
SatEvo     Jun 29 19:15     Jul  2 06:07 +-14h
SatEvo     Jun 30 18:55     Jul  2 04:06 +-10h       20.6 S    85.6 W
SatEvo     Jul  1 22:35     Jul  1 20:48 +-1h        18.1 S    19.9 E

Final (?) elset (51 sec early against yesterday's prediction):
DSP 19 Titan4r  10.0  2.5  0.0  3.0 d 31.4       152 x 114 km
1 25670U 99017B   99182.76962001  .17244808  00000-0  92817-4 0  1689
2 25670  28.6032  35.5165 0029192 335.8368  24.1413 16.52332186 13070

SatEvo prediction for final rev:
DSP 19 Titan4r  10.0  2.5  0.0  3.0 d 31.4       134 x 107 km
1 25670U 99017B   99182.82989902  .48801974  30158+1  15579-3 0 91687
2 25670  28.6024  35.0239 0020585 336.6374  23.2691 16.57333101 13083

Note: 
The final decay notice from SpaceCom, with its very low uncertainty
in decay estimate of one minute was posted as I prepared this note.
Once again, the lifetime-extension due to the atmospheric flow 
transition was not much obvious - I had been expecting it to last
another 5-6 hours. The other surprise is that the perigee fell as 
quickly as it did today, at least according to the published elsets.
The perigee was falling almost as quickly as the apogee during a 
6-orbit spell today (19 vs 20 km) - very odd considering the
eccentricity of the orbit. The normal behaviour is for the perigee to
fall much more slowly than the apogee so that the orbit tends to
circularise.
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Object: #12133 = 81-  2 A = Molniya 3-14

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

SpaceCom   Jun 29 16:23     Jul  3 16:02 +-2d        43.6 S   179.8 E
SpaceCom   Jul  1 08:52     Jul  3 00:37 +-1d        15.8 S    75.5 E

SatEvo     Jun 29 19:10     Jul  4 01:22 +-1.2d
SatEvo     Jun 30 18:45     Jul  3 19:22 +-20h
SatEvo     Jul  1 22:45     Jul  4 00:59 +-18h

Latest elset (5.7 min early against an extension yesterday's 
prediction):
Molniya 3-14                                     2756 x 85 km
1 12133U 81002A   99182.85080792  .44415708  18790-4  67857-3 0  2529
2 12133  61.9055  16.8206 1712082 281.9591 220.0803 12.60632433 50164

SatEvo prediction:
Molniya 3-14                                     2622 x 84 km
1 12133U 81002A   99183.05234605  .45004702  43505-1  63701-3 0 92527
2 12133  61.8933  16.3185 1640781 282.0174  60.1296 12.77174814 50198
Molniya 3-14                                     2271 x 84 km
1 12133U 81002A   99183.51464691  .52374048  64678-1  65203-3 0 92522
2 12133  61.8707  15.1096 1447414 282.1593  62.0425 13.21966838 50256

Note: Several of the latest elsets yield perigee distances that are
probably 10 or more km too low. The fitted SatEvo evolution leaves 
rather high residuals so the prediction is more uncertain than usual.
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Alan
-- 
 Alan Pickup | COSPAR 2707:  55d53m48.7s N  3d11m51.2s W   156m asl
 Edinburgh   | Tel: +44 (0)131 477 9144     Fax: +44 (0)870 0520750
 Scotland    | SatEvo page:   http://www.wingar.demon.co.uk/satevo/