Re: Decay of #12986 81-113D

Alan Pickup (alan@wingar.demon.co.uk)
Tue, 13 May 1997 22:40:23 +0100

The perigee heights for the four latest elsets from OIG (below) don't
look too convincing but, on past form, the implied equator crossing
times are probably close to reality.
SL-6 r2                                          17519 x 59 km
1 12986U 81113D   97127.88768816  .10749644  00000-0  15529-3 0  8964
2 12986  62.3423 110.1158 5755849 264.7990  30.9563  4.64827767116448
SL-6 r2                                          13086 x 107 km
1 12986U 81113D   97132.29533603  .16187126  10522-5  26658-2 0  8987
2 12986  62.3739 107.5429 5001821 264.8712  40.5896  5.87483033116486
SL-6 r2                                          11999 x 89 km
1 12986U 81113D   97133.28953910  .21202943  24953-5  14510-2 0  8993
2 12986  62.3740 106.8291 4793568 264.9244  51.0436  6.27072457116546
SL-6 r2                                          12005 x 89 km
1 12986U 81113D   97133.28504175  .21199527  24907-5  14386-2 0  9004
2 12986  62.3740 106.8325 4794768 264.9242  40.8932  6.26881255116545

Forcing a SatEvo evolution through the equator crossings, and keeping
the perigee at 88 km, leads to the following prediction. The implied
decay is on May 22. However, lunisolar gravitational effects should push
(pull?) the perigee another 2 km lower over the next week, bringing it
down a little earlier, say May 20.
Prediction:
SL-6 r2                                          11273 x 88 km
1 12986U 81113D   97134.06716437  .20735414  77642-2  12442-2 0 99008
2 12986  62.3087 106.2230 4637417 264.9750  42.4724  6.55662420116594
SL-6 r2                                          10662 x 88 km
1 12986U 81113D   97134.66624339  .22236675  90022-2  12511-2 0 99004
2 12986  62.2588 105.7240 4498070 265.0188  43.9422  6.81383970116636
SL-6 r2                                          10070 x 88 km
1 12986U 81113D   97135.24278788  .23916375  10479-1  12617-2 0 99009
2 12986  62.2123 105.2144 4355878 265.0653  45.4502  7.07968464116670
SL-6 r2                                          9494 x 88 km
1 12986U 81113D   97135.79772609  .25808052  12321-1  12764-2 0 99005
2 12986  62.1657 104.6936 4210303 265.1147  46.9999  7.35534382116715

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
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