# predicted elset for Spektr

From: Mike McCants <mike_at_comshare.com>
Date: Fri, 26 May 1995 15:22:59 -0400
```>Walter:
>I don't know how to convert the information given into anticipated elsets

I could send you an executable for "sgp4" that would print x,y,z coordinates
and velocities.  It shows that the current velicity for Spektr is about
7.7 Km/sec.  So, a delta v of 7.6 m/sec is a change of about 0.001.

It turns out that this translates into a change in semi-major axis of
about 0.002.  (Assuming that they have pointed the thrust in the
most useful direction - raising the orbit.)  So, the semi-major axis
will increase from about 6720 to 6733 Km.  This also translates into
a change of period and mean motion of about 0.003.  So, this would
decrease the mean motion from 15.7564 to 15.7102.  The period would
change from 91.39 to 91.66.  This is about 16 seconds per revolution,
so it will be 16 seconds later than predicted for each revolution
after the burn.

Note, however, that the elset has a pseudo-bstar of 10000-4 and what
seems to me a drag value that is much too small.  I changed the drag
to 0.00030000 below.

On May 26 at 23:35:36, Spektr is near an apogee.  So I would presume that
the burn will raise the perigee.

The change in eccentricity should be smaller by 0.002, so it would go
from 0.00447 to 0.00247.  The location of perigee will stay the same.

The other orbital parameters should not be significantly affected.

I could send you a program that would generate elements for each equator
crossing in the future and then you would pick the one closest to the
time of the burn and change its mean motion and eccentricity.

I came up with:

1 23579U 95024A   95146.99893520 0.00030000  00000-0  17833-3 0    07
2 23579  51.6512 264.2900 0044739  68.4793 291.5205 15.75750563    03

for the equator crossing right after the burn, and thus

1 23579U 95024A   95146.99893520 0.00022000  00000-0  16736-3 0    09
2 23579  51.6512 264.2900 0024739  68.4793 291.5205 15.71130563    09

after the burn.

Of course the June 1 burns will bring it right next to Mir.

Mike
```
Received on Fri May 26 1995 - 16:21:45 UTC

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