Re: Phobos-Grunt: a small surprise in ESA's confirmation of decay estimate

From: Paul Salanitri (paul.salanitri@gmail.com)
Date: Wed Jan 25 2012 - 23:14:20 UTC

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    10km v 80km.
    
    This is very interesting.
    
    In conversing with Nicholas Johnson (NASA) about the UARS re-entry, he
    advised the "TIP" re-entry was relating to an altitude of approximately
    80km.  So this actually makes it all the more intriguing.
    
    Just to give an idea what the difference MAY be, looking at numbers already
    generated from a numerical simulator:
    
    The difference between 80km and 10km is indeed 7 minutes, but it is also
    2,500km ground track.
    
    Here is a raw dump of a run performed earlier (I will run it again later to
    get better steps, and re-adjust the position to be in line with Phobos
    Grunt's re-entry):
    
    (These lat long are not directly relevant, just the relative change and the
    time/altitude, this is also for a particular object CdA/m that doesn't
    "break up" - but it at least gives an idea)
    ---------------------------------------------------------------------------------------------
    17:29:56 UT 107.610 km  geolat  34.972432 geolon 109.124565
    17:36:44 UT  97.455 km  geolat  14.522491 geolon 129.258136
    17:43:39 UT  86.700 km  geolat  -8.017417 geolon 145.786965
    17:47:20 UT  76.714 km  geolat -19.765310 geolon 155.013551
    17:49:14 UT  67.322 km  geolat -25.532820 geolon 160.252997
    17:50:50 UT  53.509 km  geolat -30.040255 geolon 164.917605
    17:51:43 UT  40.673 km  geolat -32.154646 geolon 167.346721
    17:52:03 UT  34.383 km  geolat -32.771831 geolon 168.092097
    17:52:36 UT  23.272 km  geolat -33.417827 geolon 168.892862
    17:52:59 UT  16.164 km  geolat -33.614196 geolon 169.141249
    17:53:22 UT   9.801 km  geolat -33.697632 geolon 169.247846
    17:53:23 UT   9.536 km  geolat -33.699827 geolon 169.250664
    ---------------------------------------------------------------------------------------------
    
    Paul Salanitri
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