From: utzoo!decvax!cca!REM@MIT-MC@sri-unix
Newsgroups: net.space
Title: solar power on the moon
Article-I.D.: sri-unix.3371
Posted: Mon Sep 20 16:44:20 1982
Received: Tue Sep 21 09:45:30 1982

From: Robert Elton Maas 
    Date: 18 Sep 1982 1825-EDT
    From: Margot Flowers 
    If solar energy sufficient for the needs of the dark half could be
    generated at the poles (which would always recieve sunlight that
    is not greatly diminshed by atmosphere as it is on the earth), 
That's wrong. The Moon tips north and south with respect to the sun,
just like the Earth does (Summer and Winter), although not the same
amount. The effect is similar. Half the year the north pole is in
darkness and half the year the south pole is in darkness, with some
grazing lighting during the boundary region (Spring and Autumn
equinox). A high tower might get light a little more than half the
time at either pole, whereas a ground-based station might get light a
little less than half the time. Two high towers are need for coverage
all the time (except during eclipses).
								   then
    the farthest transmission lines would have to reach would be to the
    moon's equator, at most "only" one quarter the diameter of the moon
    (still a somewhat long distance).
Your geometrical terminology is lacking. The distance around the moon
is called the "circumference", not the "diameter". You're off by a
factor of PI (3.1415926535...).
But because each pole gets light only half the time, there's an
additional factor of two, because worst case is supplying the south
pole from the north pole during southern Winter and vice versa during
northern Winter. Thus you're really off by a factor of 6.

I propose three stations on the equator separated by one third of the
circumference. That way each supplies energy for a little less than
half, and their less-than-halves overlap allowing smooth transition
from one to the next, avoiding power glitches as current in cables is
reversed gradually between the two sites. Except for the master trunk
that girdles the Moon at the equator, worst case is quarter circumference.
(That proposal is in the context of centralized production. Acutally I
prefer distributed production whereby each station has its own solar
energy, with computer making it track the sun, and decreasing level of
activity each night to conserve limited energy storage. At least in
the forseeable future, say 50 years.)