Iridium 38 replacement by Iridium 82

In September 2003, Iridium 82 replaced Iridium 38 in the operational constellation

Up to and including September 13, 2003, Iridium 82 was one of the spares for orbital plane 6, in the lower orbit normal for spares:

IRIDIUM 82
1 25467U 98051A   03256.55538426  .00000141  00000-0  27916-4 0  2179
2 25467  86.5193 322.0347 0002244  72.0239 288.1216 14.54938349266286
IRIDIUM 82
1 25467U 98051A   03256.83048828 +.00000083 +00000-0 +14370-4 0 02289
2 25467 086.5187 321.9194 0002211 073.1975 286.9533 14.54938582266322

Iridium 82 was then raised toward the operational orbit, evidently to occupy the slot previously occupied by Iridium 38.

IRIDIUM 82
1 25467U 98051A   03257.38069343 -.04380318  00000-0 -13180+1 0  2186
2 25467  86.4973 321.6959 0001278  77.4219 274.8400 14.48226474266401
IRIDIUM 82
1 25467U 98051A   03257.52046810 -.04326203  00000-0 -13382+1 0  2194
2 25467  86.4960 321.6372 0000965  67.5238 292.5964 14.46802375266421
IRIDIUM 82
1 25467U 98051A   03257.86674812 -.04238439  00000-0 -14051+1 0  2209
2 25467  86.4778 321.4863 0003745  73.6969 286.4548 14.43260405266473
IRIDIUM 82
1 25467U 98051A   03257.93611933 -.04246631 +00000-0 -14293+1 0 02258
2 25467 086.4636 321.4624 0005375 076.1405 284.0352 14.42511663266487
IRIDIUM 82
1 25467U 98051A   03258.21384491 -.04065197  00000-0 -14339+1 0  2219
2 25467  86.4628 321.3488 0005352  75.0133 285.1657 14.39932421266526
IRIDIUM 82
1 25467U 98051A   03258.49204028 -.03861924  00000-0 -14214+1 0  2220
2 25467  86.4493 321.2268 0005163  88.6957 271.4964 14.37523750266567
IRIDIUM 82
1 25467U 98051A   03259.60924828  .00000301  00000-0  10000-3 0  2233
2 25467  86.3864 320.7511 0010213 147.3080 219.3157 14.34370943266729
IRIDIUM 82
1 25467U 98051A   03259.67776133  .00000303  00000-0  10000-3 0  2247
2 25467  86.3846 320.7306 0006750 102.9450 257.2565 14.34794246266731
IRIDIUM 82
1 25467U 98051A   03260.58467968 -.00689246  00000-0  00000+0 0  2258
2 25467  86.3837 320.3504 0013857  72.4318 290.9837 14.34924756266857
IRIDIUM 82
1 25467U 98051A   03260.58468042 -.00676192  00000-0  00000+0 0  2269
2 25467  86.3837 320.3501 0015303  87.6803 275.6708 14.34921477266853

By September 17, 2003, Iridium 82 had more or less arrived on station, and was having fine adjustments made to its orbit:

IRIDIUM 82
1 25467U 98051A   03260.72386752 -.00030972  00000-0 -11109-1 0  2278
2 25467  86.3840 320.2892 0004956 108.6173 249.8927 14.34251826266888
IRIDIUM 82
1 25467U 98051A   03261.21255775 -.00025253  00000-0 -90546-2 0  2283
2 25467  86.3854 320.0838 0004679 109.3479 250.8222 14.34234353266954
IRIDIUM 82
1 25467U 98051A   03262.53816494 -.00014780  00000-0 -52989-2 0  2293
2 25467  86.3885 319.5294 0004499 105.5405 254.6288 14.34192107267140
IRIDIUM 82
1 25467U 98051A   03262.88700854 -.00006897  00000-0 -24732-2 0  2300
2 25467  86.3880 319.3818 0004466 110.7918 249.3898 14.34200735267196
IRIDIUM 82
1 25467U 98051A   03262.95677495 -.00006111 +00000-0 -21919-2 0 02327
2 25467 086.3883 319.3525 0004448 110.6489 249.5209 14.34201517267205
IRIDIUM 82
1 25467U 98051A   03263.51492440 -.00001640  00000-0 -59301-3 0  2313
2 25467  86.3888 319.1190 0004658 111.9556 248.2199 14.34207379267282
IRIDIUM 82
1 25467U 98051A   03263.79399667 +.00000241 +00000-0 +78862-4 0 02431
2 25467 086.3892 319.0027 0004797 110.6340 249.5374 14.34211844267322
IRIDIUM 82
1 25467U 98051A   03264.21260786  .00001118  00000-0  39216-3 0  2329
2 25467  86.3894 318.8278 0004602 107.1069 253.0626 14.34215000267387
IRIDIUM 82
1 25467U 98051A   03264.91029390 +.00001226 +00000-0 +43060-3 0 02478
2 25467 086.3895 318.5356 0004689 105.8069 254.3646 14.34216919267489

Fine adjustments continued over the next few days. It looks as if there may have been some difficulty getting Iridium 82 accurately on station. Its orbit remains slightly more eccentric that the rest of the operational constellation.

On October 7, an elest appeared which showed Iridium 82 in an an orbit about 10km below, and somewhat more eccentric than, the operational orbit:

IRIDIUM 82
1 25467U 98051A   03280.46862331  .00168483  00000-0  59459-1 0  2450
2 25467  86.3953 312.0281 0010866 102.7867 258.1314 14.34767939269711

However, subsequent elsets show as it as still on station, so the above elset must be dismissed as the product of a glitch in the system. It does not appear to relate to any other object.

IRIDIUM 82
1 25467U 98051A   03280.81753489  .00000293  00000-0  97648-4 0  2462
2 25467  86.3874 311.8727 0004734  70.9443 289.2276 14.34218691269761

Iridium 38 seems to have been slowly losing altitude since around the beginning of August 2003. However, this decay was so gradual that it had only drifted ahead of its nominal position, at the time Iridium 82, took over by about 30 seconds (increasing by around 1 second per day).

IRIDIUM 38
1 25043U 97069E   03210.83971462  .00000103  00000-0  29552-4 0  1297
2 25043  86.3971 341.0906 0002135  84.1867 275.9580 14.34217372299479

IRIDIUM 38
1 25043U 97069E   03263.23549713  .00000172  00000-0  54376-4 0  1994
2 25043  86.3964 319.2066 0002482  72.2761 287.8703 14.34237049306988

Probably Iridium 38 had remained operational from the communications point of view, though unable to maintain its precise position in the constellation.

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