UARS: Evolution of Decay Predictions

From: Ted Molczan (
Date: Fri Sep 23 2011 - 12:59:03 UTC

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    I awoke to find several updated USSTRATCOM TLEs at Space Track, which Satevo propagates to decay on Sep 24 between about
    02:00 and 04:00 UTC, indicating a significant trend toward a later decay. For now, it looks like 00:00 - 04:00 UTC, but
    it could well happen even later. UARS will pass over North America and Europe several times during this period, but it
    will spend most of its time over oceans and sparsely populated land. I hope to have more information on ground tracks
    later today.
    I have updated the plots I posted yesterday to include the new predictions.
    The first plot shows the past two weeks. Two weeks ago, it appeared that the decay would occur during Sep 29 - Oct 01
    UTC, but the increased drag associated with high geomagnetic activity during Sep 9-13, advanced the decay by about one
    The second version focuses in on the past four days, during which the predicted decay has ranged between Sep 23, 14 h
    and Sep 24, 07 h UTC.
    Ted Molczan
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