Re: Decays on April 27th

From: Alan Pickup (alan@wingar.demon.co.uk)
Date: Sun Apr 30 2000 - 11:45:50 PDT

  • Next message: Daniel Deak: "Re: Decays on April 27th"

    Phillip Clark is probably referring to a report from S Africa of what
    appears to be the impact on April 27th of a chunk of satellite debris
    into a field 25 km from Worcester which lies about 100 km ENE of Cape
    Town. This report appeared in a message from Keith Gottschalk in the
    FPspace mailing list this (UK) afternoon, quoting an article in the
    "Saturday Argus". Unfortunately, no time is mentioned, though, with
    farmers and labourers nearby at the time, it was almost certainly in
    daylight.
    
    As Phil mentions, there were two decays on that day: #26302 (00- 21 B =
    Progress M1-2 Soyuz rocket) and #23834 (96- 19 B = GPS 2-25 Delta 2
    rocket).
    
    #26302 had a SE-wards pass over central and eastern South Africa at
    about 08:05 UTC, but did not pass near Worcester. The epoch of the final
    elset is a few minutes later than this, but that elset is clearly
    suspect, with a negative drag term. Both SpaceCom and I put this decay a
    couple of hour later, at 10:42 and 10:51 respectively, when the orbit
    could not have taken it over S Africa.
    
    However, if this is satellite debris, I am sure that it came from
    #23834, the Delta 2. SpaceCom put the decay of this at 13:18 UTC near
    21.8 S, 16.0 W, over the S Atlantic. I estimated 13:29 UTC near 34.0 S,
    52.3 E, which is SE of Madagascar. Between these two positions, there is
    ESE pass over the SW tip of S Africa that passes very close to
    Worcester. If it had been in orbit, the pass above Worcester would have
    occurred at 13:22 UTC. Given the retardation during re-entry, and the
    time to fall to the ground, my estimate of when the debris might have
    landed is 13:26 UTC. It would be interesting to know if this time is
    consistent with the reports from the ground.
    
    The final published elset for #23834 is:
    GPS 2-25 r1      5.9  2.4  0.0  5.0 v   12       144 x 127 km
    1 23834U 96019B   00118.51427727  .42079649  13253-5  33611-3 0  8671
    2 23834  35.0267 183.8600 0012991 171.4994 189.0574 16.51367527228838
    This is for the beginning of that decay orbit and is in close agreement
    (showing it only 1.4 seconds early) with the prediction I had posted 6
    hours earlier. It was 3.9 sec early against the prediction I'd posted
    almost 20 hours earlier.
    
    
    Alan
    -- 
     Alan Pickup | COSPAR 2707:  55d53m48.7s N  3d11m51.2s W   156m asl
     Edinburgh   | Tel: +44 (0)131 477 9144     Fax: +44 (0)870 0520750
     Scotland    | SatEvo page:   http://www.wingar.demon.co.uk/satevo/
    
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