Decay watch: Iridium Delta and others

Alan Pickup (alan@wingar.demon.co.uk)
Sat, 22 Aug 1998 15:24:16 +0100

The latest elset for the decaying Iridium 50 Delta 2 rocket is:

Iridm 50 Delta r 5.9  2.4  0.0  5.6 d            256 x 200 km
1 25174U 98010F   98234.41931980  .01368189 -13188-5  78179-3 0  2821
2 25174  83.6318 253.8399 0042153   4.1781 355.9875 16.16797281 28870

I anticipate decay at about August 26.6 +-0.8 day. At present this is
sunlit all around its orbit, being best placed for observation as an
evening object in the S hemisphere.  SatEvo-predicted elsets:
Iridm 50 Delta r 5.9  2.4  0.0  5.6 d            249 x 198 km
1 25174U 98010F   98235.03789206  .01608735  12711-2  81534-3 0 92821
2 25174  83.6311 253.2350 0038905   1.6191 358.3935 16.18656630 28970
Iridm 50 Delta r 5.9  2.4  0.0  5.6 d            235 x 192 km
1 25174U 98010F   98236.02600847  .02100867  22056-2  82852-3 0 92825
2 25174  83.6298 252.2648 0033060 357.5155   2.4681 16.22279348 29139
Iridm 50 Delta r 5.9  2.4  0.0  5.6 d            217 x 183 km
1 25174U 98010F   98237.01155881  .03123283  54611-2  83928-3 0 92823
2 25174  83.6280 251.2909 0025952 353.3978   6.5678 16.27277520 29290

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

The recent Long March launch of Iridiums 3 and 76 has left a number of
decayers. Current elsets for these are:
Iridm 3 CSL02 r                                  639 x 179 km
1 25433U 98048C   98234.32407751  .00726851 -13804-5  66399-3 0    78
2 25433  86.3709 247.8466 0338762 161.5684 199.8205 15.52813704   368
Iridm 3 CSL02 S/D                                612 x 194 km
1 25434U 98048D   98234.06219451  .00371927 -13936-5  53089-3 0    65
2 25434  86.3168 247.9667 0307846 148.9072 213.0727 15.54673695   320
Iridm 3 CSL02 deb E                              667 x 173 km
1 25435U 98048E   98234.02603161  .08108730 -20216-5  63763-2 0    85
2 25435  86.0487 248.0265 0362808 159.8369 201.5668 15.48916894   316
Iridm 3 CSL02 deb F                              690 x 169 km
1 25436U 98048F   98233.83147799  .07831273 -19568-5  55021-2 0    84
2 25436  86.6497 248.1386 0381907 167.5428 193.5628 15.45671898   283
Iridm 3 CSL02 deb G                              628 x 178 km
1 25437U 98048G   98234.28125741  .08444683 -20418-5  74182-2 0    78
2 25437  86.0744 247.8405 0331678 154.3237 207.3409 15.54813740   356
Iridm 3 CSL02 deb H                              604 x 172 km
1 25438U 98048H   98234.27596301  .09547517 -21180-5  66804-2 0    83
2 25438  86.7046 247.9183 0318925 162.8644 198.3695 15.59979701   350

My decay forecasts (almost identical for the debris objects):

       #25433 = 98- 48 C   The rocket         September 18
       #25434 = 98- 48 D   Smart Dispenser      October  6
       #25435 = 98- 48 E   debris                August 24.3
       #25436 = 98- 48 F   debris                August 24.3
       #25437 = 98- 48 G   debris                August 24.3
       #25438 = 98- 48 H   debris                August 24.2

As with the Iridium 3 rocket, all these are sunlit around their entire
orbits.

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

The Iridium 69 Smart Dispenser is also heading for decay, at about
August 29 by my current analysis. The latest elset is:
Iridm 69 CZ S/D  4.0  2.0. 0.0  5.5 d            327 x 173 km
1 25322U 98026D   98234.45384530  .01270011 -14627-5  52094-3 0  1798
2 25322  86.2517 234.5784 0116664  70.0262 291.3519 16.08878142 17608
Again, this appears to be sunlit all around its orbit, being best as a
morning object in the S hemisphere.

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

Elsets for all the above objects are in my select.tle and dklist.tle
files, being updated frequently at
        http://www.wingar.demon.co.uk/satevo/tle/

Alan
-- 
 Alan Pickup | COSPAR site 2707:   55d53m48.7s N   3d11m51.2s W    156m asl
 Edinburgh   | Home:      alan@wingar.demon.co.uk       +44 (0)131 477 9144
 Scotland    | SatEvo satellite page: http://www.wingar.demon.co.uk/satevo/