
How to write your name on the moon - coffeecodecouch
http://canonicalmomentum.tumblr.com/post/86342049687/how-to-write-your-name-on-the-moon?r=s
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yaakov34
I think the calculations are extremely wasteful, since the writing being
discussed would actually be visible from much of the solar system, while we
only need it to be visible from Earth. The Earth subtends 1.2 millisteradians
as seen from the moon, which is about 1/5000 of the whole half sphere. So if
you place a mirror on the moon which throws a sunspot on the Earth, you can be
5000 times as efficient in emphasizing that patch of ground as if you simply
paint it completely white (the reflectance of the moon itself is only 12%, and
of course its light is diffuse and not concentrated on Earth).

Going with his surface area of 500,000 sq. kilometers, we would only need
about 100 sq. kilometers of mirrors, spread randomly through the area to be
emphasized, to produce a readable message on Earth. This is actually doable,
although hard, and the message would only be visible at one particular angle
(say, full moon directly overhead edit: depending on how much of the Earth you
cover and how well, it may not need to be directly overhead), unless you want
articulated mirrors.

In fact, I read, long ago, an article about a guy that performed this hack on
Earth during the fairly early days of satellite photography. He drove around
the desert in Southeast US, and placed small reflectors at angles calculated
to reflect sunlight into a passing satellite. This resulted in huge
overexposed letters in the satellite image, since each reflector exposed a
very large pixel/grain of the fairly low-resolution satellite. I can't seem to
find this article anywhere, although I remember it pretty clearly. If you can
find it, I promise to upvote your submission!

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Someone
You don't need big craters to create a shadow. Plough the moon, turning over
the dust in 20 cm wide and 10 cm high piles. At a square km per machine per
week (I'm making that up, but it is less than a hectare per hour, and the
world record is over 4 square km/day
([http://www.guinnessworldrecords.com/records-1/ploughing-
area...](http://www.guinnessworldrecords.com/records-1/ploughing-area-covered-
in-24hrs/)), likely on way better ground, but not nuclear-powered, either),
that's 'only' 10,000 machine-years. Turn 10,000 nuclear warheads into crude
nuclear engines, and you can do it within a few years.

I might help spending time choosing an area where you can avoid deep craters
and have enough dust to form the piles.

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dchichkov
It seems like it would be much easier to finally make some self-replicating
bots, or just self-repairing bots, or even just a small factory that can
produce bots... And leave it there for a couple of decades with the task of
writing that 'hello' message.

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yzzxy
Cellular automata sent to billboard the moon would be a great concept for a
sci-fi short story.

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anon4
Given the low reflectivity of the moon, can't we "just" lay down a lot of
mirrors in the shape of the letters we want?

Build a rocket ship that makes a flyby of the moon, drops some mirrors and
returns. Maybe it could rendezvous with the ISS to get a fresh supply of
mirrors and we send the mirrors to the ISS by conventional means.

And when I say mirrors, I am thinking of really thin ones. Really, just giant
sheets of aluminium foil. I suspect they'll naturally drift around and degrade
over time, giving people something to think about as a poignant metaphor of
some artistry thing.

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drakaal
You know how the moon looks HUGE when it is low on the horizon? That is just
perspective, but you should write on the moon then. Your brain does this built
in Zoom thing when it has something to scale against, and you could use that
to your advantage.

Rather than smoothing the surface to reduce shadows, Why not write in a color
other than black? I'm thinking a laser in Green would work well and would
contrast against black and white quite well.

More authoritative, and fun [http://what-if.xkcd.com/13/](http://what-
if.xkcd.com/13/)

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nathannecro
Fantastic!

As a side note: I wasn't aware how _little_ surface damage nuclear weapons
actually inflict. I was always under the impression that a nuke would level
entire cities + surrounding suburbs.

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qbrass
They do more damage when detonated in the air above the target, where the
shockwave can do most of the work.

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spiritplumber
In this case however, no atmosphere = no shockwave.

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kbob
How about writing on the moon while it's dark? Reflect enough sunlight onto
the dark side to make it about as bright as the light side. That would give a
good contrast.

You would need an array of mirrors about the size of France in orbit about the
earth. Thin film mirrors would be a lot lighter than asphalt. Precisely aiming
the mirrors would be the challenge.

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tagawa
For those interested in the laser bit (hey, who isn't?), there's already a
laser being fired at the moon from the Apache Point Observatory in New Mexico,
measuring the earth-moon distance. Bonus cool photo:
[http://apod.nasa.gov/apod/ap140418.html](http://apod.nasa.gov/apod/ap140418.html)

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ant_sz
If we really has the ability to write on the moon, what will most people agree
to write? hm....It's a difficult problem.

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CamperBob2
my sister's mom makes $174/hr by writing on the moon. She has been out of a
job for ten months but last month her check was $16431 just posting ads on the
moon for a few hours. look at this web-site....

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avmich
You just have to invent a way to change albedo of a surface using only local
resources. You also need to think how exactly you're going to cover that
territory of France - how heavy should be robots doing that, how many of them,
how they'll withstand harsh environment - and require replacements...

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quink
OK, why are we making it darker? Can't we just LED the place up - sure, it'll
require ongoing power, but it must be cheaper and more flexible.

Imagine you did this on Earth and how much you could save over nuclear bombing
the place with paint. In fact, we already did it, as a side effect.

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kubiiii
Great read. I thought that maybe it would be even more impossible to project
the text on the moon with a geostationary moon projector. I heard that making
a geostationary moon satellite is tricky, adding to the benefits of this
solution.

