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Path: utzoo!henry
From: henry@utzoo.UUCP (Henry Spencer)
Newsgroups: sci.space
Subject: Re: Powersats
Message-ID: <7278@utzoo.UUCP>
Date: Tue, 4-Nov-86 16:48:34 EST
Article-I.D.: utzoo.7278
Posted: Tue Nov  4 16:48:34 1986
Date-Received: Tue, 4-Nov-86 16:48:34 EST
References: <8611032037.AA00701@s1-b.arpa>
Organization: U of Toronto Zoology
Lines: 25

> 	Does anyone know the proposed power densities
>     of powersat receivers? ...

Roughly comparable to normal sunlight, so the heating load by itself is
not enormously significant.

(The reasons to use microwaves from powersats rather than just settling
for normal sunlight are (a) much higher conversion efficiencies, and
(b) the powersat beam is there day and night and largely ignores clouds.)

> 	The reason I'm asking this is to get a feel for 
>     how good a weapon a powersat would be...

A pretty poor one.  The physical size of the transmitting antenna dictates
how tight the focus can be, so one can set limits by restricting antenna
size.  Powersats per se are intended to be built so that they need a guide
signal from the ground for antenna focusing, also.  Custom-building one as
a weapon might eliminate the need for a guide beam, but the limitations of
focus based on antenna size are quite fundamental.

The above is for microwave transmission; laser transmission is a different
and rather less comforting story.
-- 
				Henry Spencer @ U of Toronto Zoology
				{allegra,ihnp4,decvax,pyramid}!utzoo!henry