Re: 12986 Evolutions and extrapolations.

Bjoern Gimle (b_gimle@algonet.se)
Thu, 15 May 1997 22:32:50 +0200

Hi,

using SatEvo to continue Alan's evolution for day 135.2 ( I saw only
a slight correction to the most recent 113.28 elset at OIG, nothing
from Alan ): 

SL-6 r2       135.2   norm                      19352 x 88 km
1 12986U 81113D   97135.93318297  .26318820  12849-1  12807-2 0 99003
2 12986  62.1555 104.5617 4173312 265.1274  47.3944  7.42594861116728
SL-6 r2       135.2   norm                      19211 x 88 km
1 12986U 81113D   97136.06735245  .26846200  13380-1  12854-2 0 99005
2 12986  62.1451 104.4289 4136061 265.1403  47.7918  7.49727491116731
SL-6 r2       135.2   norm                      19071 x 88 km
1 12986U 81113D   97136.20024634  .27390975  13946-1  12903-2 0 99001
2 12986  62.1346 104.2955 4098540 265.1535  48.1937  7.56934770116742
SL-6 r2       135.2   norm                      18931 x 88 km
1 12986U 81113D   97136.33187532  .27954022  14548-1  12955-2 0 99007
2 12986  62.1240 104.1612 4060739 265.1668  48.5981  7.64219247116758
SL-6 r2       135.2   norm                      18792 x 88 km
1 12986U 81113D   97136.46225011  .28536273  15190-1  13010-2 0 99008
2 12986  62.1133 104.0262 4022644 265.1803  49.0061  7.71583611116766
SL-6 r2       135.2   norm                      18654 x 88 km
1 12986U 81113D   97136.59138091  .29099414  13366-1  13051-2 0 99003
2 12986  62.1024 103.8904 3984255 265.1940  49.4176  7.79028579116778
SL-6 r2       135.2   norm                      18517 x 88 km
1 12986U 81113D   97136.71927895  .29623717  13947-1  13070-2 0 99000
2 12986  62.0915 103.7537 3945655 265.2078  49.8318  7.86538684116785
SL-6 r2       135.2   norm                      18381 x 88 km
1 12986U 81113D   97136.84595729  .30165370  14568-1  13092-2 0 99003
2 12986  62.0805 103.6163 3906852 265.2219  50.2478  7.94112181116793
SL-6 r2       135.2   norm                      18246 x 88 km
1 12986U 81113D   97136.97142916  .30725284  15180-1  13117-2 0 99008
2 12986  62.0710 103.4781 3867836 265.2362  50.6676  8.01751741116805
SL-6 r2       135.2   norm                      18112 x 88 km
1 12986U 81113D   97137.09570666  .31304454  15889-1  13146-2 0 99000
2 12986  62.0598 103.3390 3828594 265.2506  51.0892  8.09460119116812
SL-6 r2       135.2   norm                      17979 x 88 km
1 12986U 81113D   97137.21880205  .31903903  16590-1  13179-2 0 99007
2 12986  62.0502 103.1991 3789113 265.2652  51.5149  8.17240230116827


I have posted charts of MM evolutions of #23596 and #12986 on
http://www.algonet.se/~b_gimle/index.htm (and /decayers.htm)

#23596 charts sho that the orbit correction system actually
as lowering MM for the first week or so after reaching MM=15.8,
and some irregularities later, while still decaying much too sloly.

A 12986 graph shows that the decay was accelerating rapidly before
the recent gap in predictions (the moon was probably pulling the
perigee down) Since then, decay is more normal, closer to linear,
and the perigee drops only about 2km this week.

This is why my first log fit was so grossly in error. Using only
the more recent values, I have a curve much closer to NPOE
evolutions, leading to decay May 19.52 for Log curve, and May 10.1
-20.3 for the most probable NPOE evolutions. Because of the
widely varying perigee heights, I had to search for Area/Mass ratios
to match observed decay rates.


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