Satellites near STS-88

Matson, Robert (ROBERT.D.MATSON@cpmx.saic.com)
Mon, 7 Dec 1998 20:14:40 -0800

Hi All,

With the talk of an STS-88 collision avoidance burn earlier in the
mission, I thought I'd take a look to see if anything else was predicted
to be buzzing by over the next few days.  Using the following elements
for STS-88:

STS-88                        
1 25549U 98069A   98341.58333333  .00000190  00000-0  87254-5 0   142
2 25549  51.5968  80.4259 0009159 270.5334 246.3631 15.59746422   502

and searching for anything coming within 100 km for which I have
elements less than 8 days old, I came up with the following
COLA output:

Target satellite perigee:   382.20 km
Target satellite apogee:    394.59 km
Velocity at perigee:     7.6822 km/sec
TLE collision search file: alldat.rev

COLA will search for satellites having altitude ranges
that intersect the range from   362.20 to   414.59 km,
and that come within 100.0 km of the target satellite at
a time within +/-   8.0 days of both satellite epochs.

Satellites in range of STS-88:  499

   Date     UTC Time   Norad         Name      Range/OrbSep  NdAng EphAge
12/ 8/1998 11:53:41.47 25120 Orb 8 Peg R/B      96.4/  43.4   63.1  +6.16
12/ 8/1998 21:05:23.20 25421 Orb 13 Peg R/B     47.6/   4.9   83.4  +5.37
12/ 9/1998  2:10:13.79 25310 Gblstr 6 Dlt R/B   29.5/   3.7   84.3  +5.89
12/ 9/1998  5:00:43.40   829 Elektron 3         30.1/  25.8  149.0  +5.66
12/ 9/1998  8:18:11.00   746 Elektron 1         34.0/  30.4  154.0  +6.26
12/ 9/1998 12:24:09.58 22878 GPS 2-23 r1        57.2/  23.2  113.8  +6.56
12/10/1998 11:15:55.16  1844 Cosmos 100 R/B     25.6/  24.1  160.7  +7.32

The Range values aren't nearly as important as the OrbSep values
since even minor variations in drag can result in large range
prediction errors after 5 days of SGP4 propagation.

Consequently, 25421 and 25310 are the ones to watch out for since
their orbital curves come within 5 km of the Shuttle's.  Here are
the TLEs used for the above 7 "targets":

Orb 13 Peg R/B   1.3  1.0  0.0  7.5 d
1 25421U 98046J   98337.50570682  .00430188  66996-4  11385-2 0  1451
2 25421  44.9253  25.2837 0168552 142.6307 218.6427 15.74165754 19005
Gblstr 6 Dlt R/B 5.9  2.4  0.0  5.0 d
1 25310U 98023E   98337.20196795  .00044889  85473-5  84489-3 0  1647
2 25310  52.9032 259.2399 0601926 138.0862 226.7764 14.51182371 32052
Orb 8 Peg R/B    1.3  1.0  0.0  7.5 d
1 25120U 97084J   98336.33797059  .00422470  70646-4  11542-2 0  3445
2 25120  44.9513  58.2186 0112385   5.2637 354.9463 15.83306803 53022
GPS 2-23 r1      5.9  2.4  0.0  5.0 v
1 22878U 93068B   98336.95639843 +.00047363 +00000-0 +89205-3 0 07627
2 22878 035.1235 084.3238 0031224 229.0878 130.7145 15.46896261285918
Cosmos 100 R/B   3.8  2.6  0.0  5.1 v
1 01844U 65106B   98337.15234145 +.00031592 +00000-0 +54231-3 0 08368
2 01844 064.9742 088.8804 0018746 268.1861 091.7220 15.50839069804396
Elektron 3       1.2  0.8  0.0  8.4 d
1 00829U 64038A   98337.54759667  .00002270  00000-0  63861-3 0   437
2 00829  60.8571 163.5484 3069148 235.3894  91.8587  8.96352984100276
Elektron 1       1.2  0.8  0.0  8.4 d
1 00746U 64006A   98337.08098271 +.00001235 +00000-0 +38665-3 0 04131
2 00746 060.8707 238.8148 3109489 198.5415 147.1169 08.87259735162112

Perhaps someone can get more up-to-date elements to see if any of
these gets closer to the Shuttle.

I checked to see if the Shuttle/satellites were sunlit during any of these
close encounters.  Both Shuttle and target satellite are sunlit for all but
two encounters:  #25310 and #00746.  For these, both STS-88 and the
satellite are in darkness.

All encounters occur in the southern hemisphere except the last with
Cosmos 100 R/B which occurs when the Shuttle is at about 5 degrees
north latitude.  If the astronauts want to see Cosmos 100 R/B zip by,
they should start looking north-northwest between the Big Dipper
and the Little Dipper at 11:15 UTC on December 10th.  Cosmos 100 R/B
will reach magnitude -2 as it zips upward (away from the earthlimb)
through the constellation Bootes and onward toward the zenith.
Of course, if the Shuttle is in its usual flight configuration with payload
bay faced toward earth, viewing away from the earth may be difficult...

Cheers,

Rob