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From: crowl@rochester.ARPA (Lawrence Crowl)
Newsgroups: sci.space
Subject: Re: Powersats
Message-ID: <22340@rochester.ARPA>
Date: Tue, 11-Nov-86 14:38:25 EST
Article-I.D.: rocheste.22340
Posted: Tue Nov 11 14:38:25 1986
Date-Received: Tue, 11-Nov-86 20:47:39 EST
References: <8611032037.AA00701@s1-b.arpa> <7278@utzoo.UUCP> <1310@ttrdc.UUCP>
Reply-To: crowl@rochester.UUCP (Lawrence Crowl)
Organization: U of Rochester, CS Dept, Rochester, NY
Lines: 28

In article <1310@ttrdc.UUCP> levy@ttrdc.UUCP (Daniel R. Levy) writes:
>In article <7278@utzoo.UUCP>, henry@utzoo.UUCP (Henry Spencer) writes:
>>(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.)
>
>There day and NIGHT?  Where does it get its night power (I am presuming
>a solar power source)?  It would have to be in a pretty durn high orbit
>( :-), and synchronous orbits are kinda low, aren't they? ) for the earth
>not to block the sun from the powersat at night!

The earth is inclined 23 degrees off the earth's orbital plane.  So, any
powersat in (geosynchronous) orbit around earth will be out of the earth's
orbital plane almost all the time, so could not possibly be blocked from
the sun.

Even if the powersat were in the earth's orbital plane, it will probably
be sufficiently far from the earth so that for most (95%?) of its orbit 
it will not be blocked from the sun.  To see this, place a cup on your desk
and draw a large circle around it.  From how many points on the circle
can you see your doorknob?

Remember, how many lunar eclipses happen?  Certainly no where near one a
month, let alone one a month for half the month.
-- 
  Lawrence Crowl		716-275-5766	University of Rochester
			crowl@rochester.arpa	Computer Science Department
 ...!{allegra,decvax,seismo}!rochester!crowl	Rochester, New York,  14627