Re: SPACE: Lunar Billboard?

From: Michael Lorrey (retroman@tpk.net)
Date: Thu Dec 26 1996 - 19:39:03 MST


John Blanco-Losada wrote:
>
> As I was riding home from my parents' house last night after celebrating
> another nice Christmas, I was struck by the bright, full moon shining in
> the clear night. I guess my subconscious thoughts did some some strange
> wanderings, and somewhere along the way the idea popped into my head of
> using the Moon as a huge billboard. This way, some intrepid group of
> entrepreneurs could sell advertising space and use the proceeds to fund
> the cost of establishing a lunar base. I envision the billboard as a
> huge digital screen, composed of huge banks of displays which form the
> equivalent of pixels. This way the ad could be changed as often as
> necessary to maximize the number of corporate sponsors.
>
> Of course the thought has its aesthetic drawbacks; after all, who wants
> to look up, as I did last night, and see a commercial that you can't get
> rid of? On the other hand, with reports of the Japanese planning a lunar
> expedition and Chinese astronauts training with Russians, how long would
> it be until we look up and see a huge Sony logo or a picture of Chairman
> Mao? I figure a bunch of capitalists may as well beat them to the punch.
> After all, as anyone who's read "The Moon is a Harsh Mistress" knows,
> whoever's sitting at the top of the gravity well can pretty much call the
> shots.
>
> I'd be interested in finding out if anyone else has already come up with
> plans for this. Just for kicks, I'd also appreciate your evaluation of
> the feasibility of this venture. For example, how big would the board
> need to be to be visible, could we use solar power to power it, etc.
>
>
"The Man Who Sold the Moon" by Robert A. Heinlein. DD Harriman financed
his moon rocket with the same blatant commercial streak as the Artemis
Project is currently doing. One of the things Heinlein had Harriman do
was approach one cola manufacturer about putting their logo on the moon,
then going to the other to pay him twice as much to put no logo there.
Doing something like this would be an interesting test to see if purists
would be willing to pay for the right to keep the moon in its original
state. Blackmail with advertising.

ALl youd really need to to do to make it work would be a large laser
collimator in the L1 lagrange point, in front of the moon, so to speak
which would illuminate whatever messages you wish to make, using the
moon as a projection screen. Youd probably get the best effect using the
dark side of the moon (in the wane-new-waxing phases). THis way you
could use the moon as a billborad during the day, and leave it "pure" or
undisturbed at night, or what the hell screw the romantics. TO power the
laser system, you'd need to project enough light to equal the 2 kW/m^2
flux of the sun on the lunar surface, and approximately double this if
you wished to use the sun illuminated areas. With a 1500 mile diameter,
thats 10.8 x 10^6 m^2, not counting the diffractive effects of
tangential areas. You then would need to determine the resolution you
wished to project, as well as the refresh rate of your pictures.

Basically, the amount of the lunar surface you want to illuminate at any
given time determines the amount of solar collectors you would need,
minus the efficiency of solar cells in space, about 33%, so if you
wanted to illuminate the whole face, you'd need collector area equal to
3 times the 10.8 billion square meters of lunar surface you wished to
illuminate. A daunting task. Of course, you could simply build a
reflector system, or possibly a fresnel lense system of equal area which
would orbit in retrograde around the moon in a period eaual to the lunar
28 day cycle around the earth, so it would always be between the moon
and the sun, and you could use the suns illumination of the moon to
illuminate a "slide" of the graphic motif you wished to project onto its
surface. By being of equal area as the lunar cross section, you would
get a neat eclipse effect which would illuminate a circular frame around
the edge of the moon, which would aid people in spotting this aetheral
sign. Damn, I like the fresnel idea, I wonder if the the the counter
periodic lunar orbit is possible?

Lessee, a 1/6th gravity equates to a 1/6th orbital velocity, or
approximately 3000 mph or less. Using a 28 day period, that equals an
orbital circumference of 2,016,000 miles, which is an altitude of 800
miles? My orbital velocity must be off, as the 17,800 mph for earth is
assuming an earth diameter planet to avoid. HMMMMM Given lunar GM equals
.0049, and a period of 2419200 seconds, to find the orbital velocity at
a 28 day period, we need the cube root of 0.0307876 / 2419200. To
calculate orbital radius from the moons center (remember its surface is
at approximately 750 miles), you need the cube root of 726408010.2949 to
get it in km x 10^2, which should be approximately 90,000 km out.
Given this, the projector station would be able to project an image
across the entire surface with a 28 day period in a retrograde orbit
about the moon. Of course, being almost 40% of the distance to the earth
at periapsis would have some significant tidal effects on the structure,
which could be countered with either solar wind, magsail, or ion thrust
(or Lorrey Drive) augmentation. If you were not in a retrograde orbit,
you would be in the Lagrange point between the Earth and Moon.

Of course if you came up with a novel energy source, you could have a
relativley small laser projeciton station that could pump to your hearts
content. Lessee, a singularity would be a decent source of power for
such an endeavor, which would also be usefull for generating antimatter
for spacecraft fuel, and being at the L1 lagrange point would be the
optimum place to have a fuel station anyhow. So lets key in a
singularity as a key economic asset for any lunar economy. The L1 point
would be the prime way point for any trade in this solar system, given
its advantageous position between the moon and earth.

Here's a twist on that idea: Suppose you develop a good sized lunar
colony system, and have a hundred million people on the moon, at least.
You could use lasers to trigger aurora effects on earth to create neon
signs visible to lunar inhabitants. how much do you think the nuts on
earth would howl at that concept? Given this, L1 station will become the
Madison Avenue of the 21st century. It will be come THE hot piece of
commercial real estate. Unfortunately, with toroidal habitat structures,
there would be no hope of getting a corner office! ;( AWWWWWW!

-- 
TANSTAAFL!!!
			Michael Lorrey
---------------------------------------------------------
President			retroman@tpk.net
Northstar Technologies		Agent Lorrey@ThePentagon.com
Inventor of the Lorrey Drive	Silo_1013@ThePentagon.com
http://www.tpk.net/~retroman/
---------------------------------------------------------
Inventor, Webmaster, Ski Guide, Entrepreneur, Artist, 
Outdoorsman, Libertarian, Certified Genius.


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