RE: FW: Space junk destroys $500 million Earth Obse

Bjoern Gimle (b_gimle@algonet.se)
Thu, 3 Jul 1997 13:59:11 +0200

>Using the Cola program it appears that #3938  68- 97BS could be a
>contender for the collision with Adeos. Using the below elements, it
>appears that #3938 was 1.5km away from Adeos at 19:52:31.9 June 25th UT.
>...Two other objects had close flybys, these were:-
>#15031  Cosmos 1570  09:45:38.8 June 28 UT 3.2km
>#21771  91- 41 D     23:37:04.3 June 26 UT 3.9km

The elsets for thes computations were a bit old, and furthermore it is
implied by the change in MM of ADEOS elsets, that the collision occurred
around June 30.2 (97181.2):

97181.21 pre-collision?  801 x 798
1 24277U 96046A   97181.21867454 -.00000043 +00000-0 +00000-0 0 02531
2 24277 098.5960 258.5286 0002590 097.1446 263.0010 14.27649283045225
97181.28 post-collision? 30 June 814 x 792 (km) 100.9 period
1 24277U 96046A   97181.28876004 -.00000043  00000-0  00000+0 0  1919
2 24277  98.6097 258.6713 0015362 162.3148 197.7449 14.27063794 45235

Running Cola on these two elsets, and more recent ones for the objects
suggested, gives no close contact with those. (And none of those other
objects have a MM change) 
The ADEOS orbit change should have been at 03:58 at 80.8N, 147W, 811 km
on June 30, 1997 (04:01 at 78.4N, 147E if using elset no.1920).
However, this is 97181.165, before the epoch of the "pre-collision" elset,
so it is questionable if the elsets were really valid at the time of epoch).
If the elsets are only slightly inaccurate, a collision at about
8:07 , 73.2S, 7E, 829 km (AFTER the post-epoch!), or some time
between those, is almost as likely :

 6/30/1997  0:37:11.9 24277 97181.28 post-collision?     36.4     -0.26
 6/30/1997  2:17:58.2 24277 97181.28 post-collision?     18.0     -0.19
 6/30/1997  3:58:12.7 24277 97181.28 post-collision?      1.7     -0.12
 6/30/1997  5:19:59.8 24277 97181.28 post-collision?     14.5     -0.07
 6/30/1997  6:08:55.1 24277 97181.28 post-collision?     12.1     -0.03
 6/30/1997  6:38:53.1 24277 97181.28 post-collision?     12.5     -0.01
 6/30/1997  8:07:02.5 24277 97181.28 post-collision?      4.9     +0.05
 6/30/1997  9:47:50.3 24277 97181.28 post-collision?     23.3     +0.12

Running COLA with the pre-collision elset against Mike McCants' ALLDAT.TLE
gave four candidates from midnight to noon June 30, intersecting the
ADEOS orbit, with distances 9.1, 10.6, 8.1, 11.6 km
With last 5 elsets for these (USSPACECOM #02669, 04944, 09681, 17842)
from OIG reduced the minima to     9.6, 9.5, 8.0 and 5.6 km

None of these showed any change in MeanMotion (except drag)

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