Decau watch update: January 6

Alan Pickup (alan@wingar.demon.co.uk)
Wed, 6 Jan 1999 20:39:26 +0000

Three of these SpaceCom decay notices have been issued since my update
yesterday:

Object                            Notice issued    Predicted decay
                                       UTC              UTC
     
#25532 = Iridium 2 Delta r        Jan  6 10:12     Jan  7 09:43 +-14h

 #4583 = Meteor 1-6               Jan  6 11:13     Jan  8 04:51 +-1d

#21148 = Lacrosse 2 r             Jan  6 00:23     Jan  9 00:31 +-2d

#25533 = Sputnik 41               Jan  4 10:29     Jan 11 06:17 +-6d

               -------------------------------

My current decay predictions and SatEvo-predicted elsets:

   #    Designation    Name               Predicted decay (UTC)

 25532   98- 66 F   Iridium 2 Delta r      January  7 10:59 +-5h
  4583   70- 85 A   Meteor 1-6             January  8.4 +-0.4d
 21148   91- 17 B   Lacrosse 2 r           January  8.8 +-0.4d
 25533   98- 62 C   Sputnik 41             January 10.7 +-0.8d

Iridm 2 Delta r  5.9  2.4  0.0  5.6 d            184 x 153 km
1 25532U 98066F   99007.00436508  .10088490  62183-1  61842-3 0 91454
2 25532  82.4335 245.0623 0023863 110.2265 250.0302 16.38914552  9718
Iridm 2 Delta r  5.9  2.4  0.0  5.6 d            169 x 145 km
1 25532U 98066F   99007.18729783  .15200659  14873+0  44403-3 0 91456
2 25532  82.4318 244.8427 0018236 109.4650 250.7320 16.43413426  9744
Iridm 2 Delta r  5.9  2.4  0.0  5.6 d            141 x 129 km
1 25532U 98066F   99007.36956855  .38117221  12682+1  33335-3 0 91454
2 25532  82.4291 244.6220 0009822 108.7000 251.4066 16.51681547  9773
Iridm 2 Delta r  5.9  2.4  0.0  5.6 d            117 x 112 km
1 25532U 98066F   99007.43003235 1.42119233  24851+2  46708-3 0 91458
2 25532  82.4271 244.5480 0004210 108.4434 251.6024 16.59471580  9781

Meteor 1-6       5.0  1.5  0.0  5.8 v            179 x 176 km
1 04583U 70085A   99007.02913757  .03128415  66079-2  41403-3 0 95566
2 04583  81.1156 353.5152 0002481 159.9395 200.0702 16.35632932550702
Meteor 1-6       5.0  1.5  0.0  5.8 v            153 x 151 km
1 04583U 70085A   99008.00559640  .08740895  58323-1  26295-3 0 95563
2 04583  81.1122 352.1429 0001313 156.0274 203.9787 16.45362645550868

Lacrosse 2 r     9.8  3.0  0.0  5.0              203 x 196 km
1 21148U 91017B   99007.00569996  .02743844  44747-2  76536-3 0 90937
2 21148  67.9460 286.1304 0005280  82.8863 277.1737 16.27513310 64625
Lacrosse 2 r     9.8  3.0  0.0  5.0              180 x 175 km
1 21148U 91017B   99008.04818875  .05988320  24586-1  75608-3 0 90935
2 21148  67.9432 282.6117 0003358  81.5042 278.5339 16.35685950 64796

               -------------------------------

My SatEvo prediction for the Iridium 2 Delta uses a "Q-factor" of 1.1 
to force a slightly slower decay than the default factor (1.0). This 
has two benefits: (a) it gives an excellent fit to the elsets over the 
past day; and (b) I expect the drag to increase more slowly than usual
as it moves into a different atmospheric flow regime over the final 
two or three orbits.

Although the decay window is still quite large (5 hours in my 
prediction), the final orbit above has it northbound over the equator
at 10:19 UTC near 17 deg W longitude, over the Atlantic. The northbound 
track to the Arctic takes it across western Ireland (in daylight) at 
10:32. I show decay while southbound over the western Pacific around 
151 deg W, 15 deg N.

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/