Re: ISS decay?

From: Denis (denis.boucher@telus.net)
Date: Sat Apr 17 2004 - 17:05:04 EDT

  • Next message: Moritz Heger: "Re: ISS decay?"

    Yes, it is. Accuracy becomes much better as one gets update TLEs and 
    decay time gets closer.
    
    Denis
    
    Allen Thomson wrote:
    >>According to my program and present ISS tle (2004-04-16 11:52:19Z), I get
    > 
    > 04 Nov 2005 16:54:03 UT. That would be  a day or two!
    > 
    > Thanks, that agrees pretty well with Mr. Heger's value.
    > 
    > I assume that both your and his projections are for natural, unboosted
    > decay?
    > 
    > BTW, I did a quick exercise with dividers on the Heavens Above ISS altitude
    > chart and came up with rough numbers that may help characterize the period
    > from mid-April 2003 to mid-April 2004.  In that time, the actual decrease in
    > mean altitude ("height") was about 30 km.  During that time, there were four
    > reboosts that raised the height by a total of about 11 km -- in other words,
    > the total natural decay was about 41 km, and reboosts made up 11 km of that.
    > Another measure is how much time was bought by the reboosts. For each
    > reboost, I measured the approximate time it took for the height to decay to
    > its pre-reboost value. Adding those up, it came to 13 weeks; since the
    > overall decay curve is approximately linear over the one-year period
    > covered, that's what you'd expect, of course: 11/41 ~= 13/52.
    > 
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    > 
    
    
    
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