Re: Flock 2B 2 (40951) Reentry Seen from Southern England, UK

From: Adam Fritzler via Seesat-l <>
Date: Wed, 5 Oct 2016 17:54:33 -0700
Hi William,

There is a good discussion of the ranging in Cyrus's paper about our
differential-drag scheme:

This is far outside my area of expertise, but atmospheric variation as you
propose certainly seems likely. Another un-modelled factor is that once the
satellite is deep enough into the atmosphere that it cannot maintain
attitude control, it will start tumbling, which is very high-drag and will
accelerate things quite quickly!


On Wed, Oct 5, 2016 at 12:11 AM, William Stewart <
> wrote:

> Hi Adam,
> Thanks for sharing. How frequently is the UHF ranging data collected and
> are you able to quantify how this compares with the radar data from
> Space-Track?
> Both your data and that from Space-Track suggested that decay would occur
> a few hours later.
> There has been an increase in auroral reports recently (which we tend to
> get around the time of the equinox - however recent activity appears to
> have been higher and more prolonged than normal). Can the "early" decay be
> attributed to the "puffing up" of the atmosphere that occurs when solar
> activity is high (not sure how the decay models take account of this ... is
> it an assumed "fixed" value or one than varies based on current data)?
>    Hope this question is "on topic".
>    Best regards
>    William
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Received on Wed Oct 05 2016 - 19:55:59 UTC

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