FSW-1 decay

bjorn@tt-tech.se
Thu, 29 Feb 1996 12:51:02 +0100

Decay predictions for FSW-1 vs. actual elsets.
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
In the period  96054.5530 - 96058.5479  ( 3.9949 days )
MM has increased from 15.7145 to 15.8146 ( 0.1001 )
This means ndot2 has been 0.01252 on average in this period.
In the period  96058.2318 - 96059.2428  ( 1.0110 days )
MM increased by 0.0258 ( ndot2=3D0.0128 )
  =20

An NPOE integration, started from 96002.17 elset, and adjusted to fit
roughly to elsets until 96047.65, gives ascending node times
96054.5307 - 96058.5255 ( 3.9948 days ) and MM about 15.72 -15.81  =20
 (0.0920 )
The MM are as good as exact ( increased from 15.1145 on 96002.17 ).
(ndot2 =3D 0.01152)
For 96058.21 - 96059.22, NPOE shows MM increasing by 0.0264 ( ndot2 =3D  =20
0.0131 )

According to this integration, the decay would occcur on Mar.11 ( 96071.6 =20=
=20
)
If adjusted for the 96054-96058 ndot2 factor, I get Mar.10 at noon.

My simple curve fits extrapolate to decay Mar.08-11
( New .gif charts may be posted on
  ftp://ftp.physics.ox.ac.uk/pub/sat/info/  as 22870-ed.zip
  Charts with a 960xx.xx date in the title bar are curve fits
  with various elset epoch ranges, those with NPOE in the
  title bar show NPOE predictions vs. actual elsets.)

However, it is probable - and indicated by the orbits of 23471 and 05244
( but not 22870 ! ) - that atmospheric scale height is much lower
than usual ( density changes more rapidly with height )
so decay could be closer to the NASA Mar.04 prediction.

If this is correct, I would be interested to know where
more accurate atmospheric model parameters for predictions
are available !

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