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From: henry@utzoo.UUCP (Henry Spencer)
Newsgroups: net.followup
Subject: Re: Alternate Energy & Microwaves
Message-ID: <4247@utzoo.UUCP>
Date: Mon, 20-Aug-84 18:54:08 EDT
Article-I.D.: utzoo.4247
Posted: Mon Aug 20 18:54:08 1984
Date-Received: Mon, 20-Aug-84 18:54:08 EDT
References: <4196@utzoo.UUCP> <369@utastro.UUCP>, <762@dual.UUCP>, <721@flairvax.UUCP>
Organization: U of Toronto Zoology
Lines: 38

> ..................................................  Lots of neat work has
> been done by unknown people in small observatories, the kind of people who
> would not get any say in which way an orbital instrument will be pointed,
> and it would be a shame to see them put out of business by SPS.

Such astronomers should make it their first order of business to find out
about the Amateur Space Telescope, a totally separate effort from the NASA
Space Telescope.  Doing astronomy in space does not require the colossal
level of investment involved in the NASA version.  Having only one telescope
in space is silly; we need lots of them.  If the AST works the way it looks
it will, this will immediately be a realistic notion.

> One question I've never heard answered has to do with the siting of receiving
> antennas for the microwaved power.  The power satelites must presumably be
> in a geostationary, and therefore equatorial, orbit.  Receiving stations
> on the equator are a long way from the industrialized northern regions.
> Overland power transmission losses from, say, Equador to the U.S. would be 
> huge, perhaps prohibitive.  If the recieving sites are to be in the U.S., 
> the beams would have to be angled through more atmosphere, and would strike
> an enlongated "footprint".  Can anyone tell me the amount of distortion
> that would be incurred angling from a geostationary orbit to central
> Nevada, for instance?

It is necessary to put the rectennas quite near the customers; long-haul
power transmission of this size is out.  (In fact, probably the best
way to do really long-range power transmission is via microwave beam
relayed by satellite!)  The added atmospheric losses are slight, since
atmospheric losses are slight to begin with.  The "footprint" will indeed
be enlongated, which will mean a somewhat larger rectenna area, but it's
not unmanageable anywhere short of the Arctic.  Nevada is at maybe 40
degrees of latitude -- I don't have a map handy -- which means that the
beam comes in at about 40 degrees off vertical.  This is enough to stretch
the North-South axis of the rectenna by 30-40%.  It's manageable.
-- 
"The trouble with a just economy is, who runs the Bureau of Economic Justice?"

				Henry Spencer @ U of Toronto Zoology
				{allegra,ihnp4,linus,decvax}!utzoo!henry