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From: henry@zoo.toronto.edu (Henry Spencer)
Newsgroups: sci.military
Subject: Re: Pegasus
Message-ID: <1991Apr18.032852.22568@amd.com>
Date: 17 Apr 91 17:59:42 GMT
References: <1991Mar30.020340.27985@amd.com> <1991Apr12.055442.14741@amd.com> <1991Apr17.055545.13756@amd.com>
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From: henry@zoo.toronto.edu (Henry Spencer)


>From: ke4zv!gary@gatech.edu (Gary Coffman)
>*Any* satellite is a global *strategic* asset. Any given target area would 
>be visible, at best, 20 minutes per day to a low orbit satellite of the
>type launchable by a Pegasus (or smaller!) rocket.

Nobody launches reconnaissance satellites into high orbit, so the choice
of launcher is quite irrelevant.  Some of the other military birds, like
the eavesdropping satellites, go into high orbits, but anything that wants
to image the ground has to stay low.

>The remaining 23 hours and 
>40 minutes of the day, the satellite would be somewhere else.

Quite true, but the question is, is this bad?  Most of the personal computers
in the world are idle 70%+ of the time.  The issue is not whether there is
capability being "wasted", but whether a dedicated system does a sufficiently
better job during the time when it *is* active.  If the small system is cheap
enough, one might even consider launching it for a single pass over a crucial
area, and never mind where it goes after that.

>Also the very 
>small payload of the suggested system would preclude the types of sensors 
>needed for effective tactical recon. ... cameras capable of the kind 
>of resolution provided by our current recon satellites would be far too large 
>and heavy for the Pegasus to launch.

You are assuming that the full resolution of current spysats is necessary
for effective tactical recon.  Considering some of the photos the Gemini
astronauts got with small cameras attached to handheld commercial telescopes
weighing only a few kilograms, I think there is reason to doubt this.

Almost any tactical commander will prefer a low-resolution photo taken where
and when he wants it over being able to read the license plates three days
later.

I would also note that small, cheap, expendable satellites can get back
some of the resolution they lose due to smaller optics, by operating in
orbits that are *too* low for the big strategic spysats.  If you don't
care what happens to the satellite after three days, you can use a rather
lower orbit than a bird that needs to last for years.  This is especially
true if the timespan of interest is hours (i.e. one pass) rather than days.

-- 
And the bean-counter replied,           | Henry Spencer @ U of Toronto Zoology
"beans are more important".             |  henry@zoo.toronto.edu  utzoo!henry