RE: What about Nanosail-D?

From: Ted Molczan (ssl3molcz@rogers.com)
Date: Fri Oct 21 2011 - 01:18:50 UTC

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    Jesus Leonardo Pacheco Fajardo wrote:
    
    > Hi all, I just send a message in Spanish, someone that speak that language please let me
    > know. In calsky.com appears that Nanosail-D's reentry occurs at 26/10/11, someone tell me
    > what it means.
    
    Calsky appears to have used Satevo to propagate the latest available official TLE, epoch 11242.252158, to decay, and is
    also using the resulting elements to generate ephemerides. (I can nearly replicate the results using that elset with
    10.7 cm solar flux of 140.)
    
    Satevo is a useful tool, but it cannot generate reliable results so far into the future (nearly 2 months) for an object
    with such a high area to mass ratio, because its rate of decay is extremely sensitive to solar and geomagnetic
    conditions, as well as its orientation.
    
    To illustrate the problem, I ran the prediction for last five TLE's in the site's database:
    
    Elset       Obj       #         Epoch          Decay        (Date)
        1     10062L    37361   11230.280982   11360.527870  (2011 December 26)
        2     10062L    37361   11231.136470   12035.105726  (2012 February 4)
        3     10062L    37361   11234.360598   12074.724489  (2012 March 14)
        4     10062L    37361   11240.082873   12005.644201  (2012 January 5)
        5     10062L    37361   11242.252158   11299.546974  (2011 October 26)
    
    Solar flux has been much greater in the interim, and there have been some strong geomagnetic storms, so the object may
    well be near decay, but it would be extremely difficult to make predictions of reasonable accuracy.
    
    Ted Molczan
    
    
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