Decay watch update: January 9

Alan Pickup (alan@wingar.demon.co.uk)
Thu, 7 Jan 1999 21:34:24 +0000

These SpaceCom decay notices are current or have been issued and 
superseded since my update yesterday:

Object                            Notice issued    Predicted decay
                                       UTC              UTC
     
#25532 = Iridium 2 Delta r        Jan  6 22:30     Jan  7 10:59 +-8h
#25532 = Iridium 2 Delta r        Jan  7 05:21     Jan  7 11:33 +-5h
#25532 = Iridium 2 Delta r        Jan  7 09:39     Jan  7 10:50 +-1h
#25532 = Iridium 2 Delta r        Jan  6 11:09     Jan  7 10:50 +-1h
#25532 = Iridium 2 Delta r        Jan  6 15:07     Jan  7 10:52 +-21m

 #4583 = Meteor 1-6               Jan  7 10:14     Jan  8 02:23 +-10h
 #4583 = Meteor 1-6               Jan  7 17:21     Jan  8 05:06 +-2h

#21148 = Lacrosse 2 r             Jan  7 01:17     Jan  9 01:25 +-1d

#25533 = Sputnik 41               Jan  7 03:47     Jan 11 04:13 +-2d

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

As can be seen above, since Harro's posting earlier today SpaceCom 
have issued a second "final" decay notice changing their time for 
the Iridium Delta 2 (#25532) decay from 10:50 UTC to 10:52 and the 
"window" from one hour to 21 minutes. It may be no coincidence that 
10:52 - 21m = 10:31 and that at 10:32 the satellite was closest to 
the Fylingdales tracking stating in Yorkshire, England as it (the 
satellite!) passed over Ireland. Did Fylingdales track it on that 
rev? If so, it has not (yet) resulted in a further elset - the last 
one published having an epoch some three hours earlier:

Iridm 2 Delta r  5.9  2.4  0.0  5.6 d            158 x 136 km
1 25532U 98066F   99007.30909295  .17370834 -13132-5  27464-3 0  1513
2 25532  82.4236 244.7007 0016816 114.5587 245.8633 16.47105820  9768

This shows it running 12 second slate against the prediction I posted 
yesterday. My own final analysis leads to decay at 11:00 UTC around 
15 deg N and 151 deg E as it approached a southbound equator crossing 
over the western Pacific. In the absence of further elsets, however, 
I'd make the uncertainty at least one hour, though.

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

My new decay predictions and SatEvo-predicted elsets:

   #    Designation    Name               Predicted decay (UTC)

  4583   70- 85 A   Meteor 1-6             January  8 05:55 +-3h
 21148   91- 17 B   Lacrosse 2 r           January  9 02:02 +-7h
 25533   98- 62 C   Sputnik 41             January 10.9 +-0.7d

Meteor 1-6       5.0  1.5  0.0  5.8 v            151 x 150 km
1 04583U 70085A   99007.88321318  .09296594  68668-1  25834-3 0 95684
2 04583  81.1064 352.3103 0000340 104.8557 255.1481 16.45840577550863
Meteor 1-6       5.0  1.5  0.0  5.8 v            144 x 143 km
1 04583U 70085A   99008.00472235  .12868660  14495+0  21407-3 0 95686
2 04583  81.1055 352.1376 0000275 104.3638 255.6392 16.48479772550881
Meteor 1-6       5.0  1.5  0.0  5.8 v            133 x 133 km
1 04583U 70085A   99008.12599369  .22886732  54360+0  19274-3 0 95682
2 04583  81.1042 351.9644 0000189 103.8707 256.1314 16.52549720550906
Meteor 1-6       5.0  1.5  0.0  5.8 v            123 x 123 km
1 04583U 70085A   99008.18648714  .43012471  22974+1  21317-3 0 95689
2 04583  81.1030 351.8775 0000125 103.6234 256.3780 16.56240524550914

Lacrosse 2 r     9.8  3.0  0.0  5.0              186 x 179 km
1 21148U 91017B   99008.04875785  .04278556  11980-1  65390-3 0 91011
2 21148  67.9420 282.6087 0005813  86.7137 273.3528 16.33816380 64793
Lacrosse 2 r     9.8  3.0  0.0  5.0              171 x 165 km
1 21148U 91017B   99008.53777763  .07500258  40451-1  63327-3 0 91015
2 21148  67.9402 280.9455 0004199  86.0609 273.9870 16.39261057 64872
Lacrosse 2 r     9.8  3.0  0.0  5.0              158 x 154 km
1 21148U 91017B   99008.78152876  .12076779  10374+0  47861-3 0 91010
2 21148  67.9388 280.1104 0003094  85.7334 274.3020 16.43851101 64919
Lacrosse 2 r     9.8  3.0  0.0  5.0              129 x 127 km
1 21148U 91017B   99009.02431423  .48896972  30159+1  30405-3 0 91010
2 21148  67.9353 279.2708 0001243  85.4042 274.6100 16.54228947 64951

Sputnik 41       0.2  0.0  0.0  9.5 v            238 x 228 km
1 25533U 98062C   99008.01832714  .01946161  19632-2  14023-2 0 91089
2 25533  51.6446  78.1715 0007057   5.0456 354.9614 16.15049404  9144
Sputnik 41       0.2  0.0  0.0  9.5 v            224 x 217 km
1 25533U 98062C   99009.00699730  .02804721  43135-2  14396-2 0 91082
2 25533  51.6432  72.7636 0005726   9.0779 350.9324 16.19636033  9300

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

My computed final orbit for Meteor 1-6 takes it northbound over the 
equator near 177 deg E (over the Pacific) at 04:28 UTC, heading towards
the Bering Sea (04:42) and northern apex. The southbound track takes it 
over Greenland (~04:54) and the NE Atlantic towards the extreme W of
Africa (05:07), a southbound equator crossing at 13 deg W at 05:11. If
it does not decay near here, the track would then carry it to the far S
Atlantic, Antarctica, then northwards towards Sydney at05:46 and another
equator crossing at 05:55 near 156 deg E, which is where I favour decay.

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/