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From: fisher@dvinci.DEC
Newsgroups: net.columbia
Subject: Launch Windows
Message-ID: <1068@decwrl.UUCP>
Date: Tue, 12-Mar-85 09:26:20 EST
Article-I.D.: decwrl.1068
Posted: Tue Mar 12 09:26:20 1985
Date-Received: Sat, 16-Mar-85 12:50:11 EST
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Organization: DEC Engineering Network
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<>

> ...the comsat uses batteries until it can reach geo, stop spinning, and
> unfold its solar panels

This may be true for some of them (the stop spinning and unfold part), but
the ones I know about are either 3-axis stabilized and don't spin at all
(like TDRSS) or are spin stabilized and spin during their entire life
(like Palapa and Westar).

I don't think this invalidates any of the other stuff about sun sensors,
etc, since a spinning satellite would still have lots of constraints.  For
example, stuff that can't spin must either be mounted on the satellite's 
spin axis, or on a "despun" section, which itself must be attached to the
satellite on the spin axis.  Not to mention mass being distributed evenly
around the cicumfrance, fuel having to drain evenly.  AND...it must be pretty
hard to change the attitude of a spinning satellite, so you want to do that as
little as possible.  What a pain!  With all that, I wonder why the launch 
window is so wide!

Burns


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