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From: moore@ucbcad.UUCP
Newsgroups: net.space
Subject: Re: Re: sattelites - (nf)
Message-ID: <42@ucbcad.UUCP>
Date: Fri, 22-Jul-83 07:28:49 EDT
Article-I.D.: ucbcad.42
Posted: Fri Jul 22 07:28:49 1983
Date-Received: Sat, 23-Jul-83 02:07:24 EDT
Sender: notes@ucbcad.UUCP
Organization: UC Berkeley, CAD Group
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#R:sri-arpa:-301500:ucbcad:9900001:000:851
ucbcad!moore    Jul 21 14:19:00 1983

	Just to put a silver spike through this topic: if you
have two objects orbiting at radii of R1 and R2 over a planet
of radius r, then the maximum angle the two objects can be
separated and still see each other is given by

	Theta_Max = arccos(r/R1) + arccos(r/R2)

For r = 4000 miles (Earth radius?), R1 = 26300 miles (geosynchronous
radius), R2 = r + 100 miles (shuttle radius?), we get 
Theta_Max ~= 94 degrees, so the shuttle will be within line of
sight of the communication satellite 2*94/360 or ~52% of the time.

	BTW, a geosynchronous satellite covers 45% of the equator and
42% of the earths surface. This is what COULD be covered, according
to the geometry of the problem; I don't know if the reception is at all
acceptable at the fringes of the covered region.

	Peter Moore

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