Laser art on the Moon!

[Bryan Ekers]

I've kicked this idea around for some time, mentioned it here and there, but now I'd like to get down to some hard-core theorizing. Given that laser shows like the one at Stone Mountain Park, Georgia (http://www.stonemountainpark.com/mini-section/default.aspx?id=5) can draw large images, what would it take to use the new Moon (i.e. the moon at a time when its sunlit face is pointed away from Earth) as a canvas?

Given the moon's apparent size (roughly comparable to a fingernail held at arm's length), I wouldn't expect readable text, but consider a corporate logo, like Pepsi's red-and-blue, or Mercedes' propellor, or anything else roughly circular. If the albedo of the moon is in the 10-15% range, how much energy is required to draw something visible to the naked eye, putting aside issues of light pollution from Earthbound sources?

[Argent Towers]

I don't have an answer, but I have to say that the idea of a corporate logo on the moon is extremely annoying. I think I would seriously consider moving to another solar system if I had to look at the Pepsi logo on the moon even once a year.

The Bat sign, though, I wouldn't mind.

[ChrisBooth12]

I believe it would actually be against the law. at least by the FCC that is.

[Kimstu]

what would it take to use the new Moon (i.e. the moon at a time when its sunlit face is pointed away from Earth) as a canvas?

Remember that when the moon is at its new phase, it's in almost the same direction as the sun. If the sun is still in the sky when you're projecting your logo onto the dark near-side surface of the moon, the visual effect is probably not going to be very impressive.

What you want is for your artwork to show up clearly on the moon against a dark sky. For that, you're going to have to accept at least a little white crescent on the otherwise dark disk of the moon, so that it will be far enough away from the sun to be visible after sunset. (And the nearly-new moon won't be above the horizon for very long itself, leaving you with quite a short display time which will probably piss off your corporate sponsors. Why not project something onto the bright disk of the full moon instead, like Batman's Bat-signal? [ETA: Hi Argent!] The full moon stays up all night and there's no direct sunlight competing with it.)

[Cabbage]

I definitely remember reading that Pizza Hut considered doing just this at one time. They abandoned it when it was pointed out that the logo would have to be the size of Texas in order for it to be legible from Earth.

Here's a reference to that story:

...they wanted to project the chain's updated logo onto the moon...(but)...the logo would have to be as big as Texas to be seen by earthlings without telescopes.

http://www.indianexpress.com/res/web/pIe/ie/daily/19991004/ibu04033.html

[GuanoLad]

The moon is a lot smaller in the sky than you think. It would have to cover the entire face of the moon to even be seen, let alone readable.

[Mangetout]

As I said in this (http://boards.straightdope.com/sdmb/showthread.php?t=321951) previous thread on the subject, I think it would be a less taxing engineering task to construct a shadow puppet the size of India, and use that to form the desired image on the moon.

[Squink]

Well, you can see the moon when it's illumined by the sun, so if you could build a laser to project the same amount of light onto a dark piece of the moon, it should be visible from earth; providing of course that the illumined area is large enough.
The sun delivers about 1370 watts of power per square meter at the earth's surface, a little more to the airless moon.
Perhaps a square kilometer of that sort of illumination would be visible from earth.
A square kilometer being a million square meters, you'd need at least a 1.37 billion watt laser.

[Saltire]

Isaac Asimov wrote a short story about someone selling advertising space on Jupiter. Apparently, aliens often came to the outer solar system to admire our gas giants on their way from one place and another, so an alien corporation wanted to project an ad slogan (for some alien equivalent to Pepto Bismol, I think) across the cloud deck. The best part of the story was the title, "Buy Jupiter!"

I hope that wasn't a totally unwelcome interjection into this thread.

[Lemur866]

Best time to do this is during a lunar eclipse. The sun won't be visible to create light pollution, and the moon will be almost as dark as a new moon.

Of course, whether people will think this is cool or annoying is a good question.

I don't think you're going to be able to draw anything visible on a full moon. There's a reason they don't do laser shows in the daytime.

[Bryan Ekers]

Using a lunar eclipse as a canvas also occured to me as I was on my way home but I see I've been beaten to it.

In any case, how far into this list (http://en.wikipedia.org/wiki/List_of_lunar_eclipses#21st_century) can we go before somebody has both the engineering capability and the balls to give it a shot?

[mks57]

The path loss from the Earth to the Moon and back to the Earth is extremely high. When lasers are used to measure the distance between the Earth and Moon, using retroreflector arrays left on the Moon by the Apollo missions and a large telescope on Earth, they are detecting individual photons at the end of the journey, and not very many of them.

See http://physics.ucsd.edu/%7Etmurphy/apollo/apollo.html for details.

[Rattlehead02]

Well, you can see the moon when it's illumined by the sun, so if you could build a laser to project the same amount of light onto a dark piece of the moon, it should be visible from earth; providing of course that the illumined area is large enough.
The sun delivers about 1370 watts of power per square meter at the earth's surface, a little more to the airless moon.
Perhaps a square kilometer of that sort of illumination would be visible from earth.
A square kilometer being a million square meters, you'd need at least a 1.37 billion watt laser.

Yeah, but can you put that frickin laser on a shark's head? Didn't think so.

[panache45]

Isaac Asimov wrote a short story about someone selling advertising space on Jupiter. Apparently, aliens often came to the outer solar system to admire our gas giants on their way from one place and another, so an alien corporation wanted to project an ad slogan (for some alien equivalent to Pepto Bismol, I think) across the cloud deck. The best part of the story was the title, "Buy Jupiter!"

I hope that wasn't a totally unwelcome interjection into this thread.
That was my first thought when opening this thread. Great story.

[Bryan Ekers]

A square kilometer being a million square meters, you'd need at least a 1.37 billion watt laser.

Well, heck, by the time that's possible, the adverts can be for "Mr. Fusion."

[Colophon]

Well, you can see the moon when it's illumined by the sun, so if you could build a laser to project the same amount of light onto a dark piece of the moon, it should be visible from earth; providing of course that the illumined area is large enough.
The sun delivers about 1370 watts of power per square meter at the earth's surface, a little more to the airless moon.
Perhaps a square kilometer of that sort of illumination would be visible from earth.
A square kilometer being a million square meters, you'd need at least a 1.37 billion watt laser.
Well no, because you could see the advert at a lot less light intensity than the full moon. I mean, you can often see the "dark" portion of a nearly new moon lit up by earthshine, which is sunlight that has bounced off the earth, up to the moon, then reflected back to earth. I'd guesstimate that the intensity is maybe a hundredth of the full moon intensity, so maybe you'd only need a 14 megawatt laser...

[drachillix]

so maybe you'd only need a 14 megawatt laser...

Sorry pal, all we got is what you see here.

[Squink]

the "dark" portion of a nearly new moon lit up by earthshine
...
so maybe you'd only need a 14 megawatt laser...
This dubious source (http://mobile.orbit.zkm.de/?q=node/165) claims that earthshine on the moon runs at about 0.1 W/sq.meter.

To outshine that, you'd need 100,000 watts per square kilometer of lunar surface.
Your 14 megawatt laser would sufice for 140 square kilometers; a circle 44.5 km in diameter.
At 384400 kilometers distance, that circle would subtend a visual angle of 0.0066 degrees. That's a pretty small spot of earthshine to be picking out!

[USCDiver]

I didn't see anyone mention it yet, but the moon isn't a flat surface. Most light that reached it from the Earth would be reflected at an odd angle. Consider the point above about the mirrors left on the surface only reflecting a few photons and extrapolate for a grey surface with boulders and craters and dust.

[Boyo Jim]

I didn't see anyone mention it yet, but the moon isn't a flat surface. Most light that reached it from the Earth would be reflected at an odd angle. Consider the point above about the mirrors left on the surface only reflecting a few photons and extrapolate for a grey surface with boulders and craters and dust.

Actually, my first thought was about how lousy a reflective surface the moon would be, aside from its convexity, or concavity, whichever -- I can never keep them straight. :p.

So, I would suggest a scattering of some kind of highly reflective powder over the lunar surface. I would imagine you could significantly reduce the power requirements by making the moon a more efficient "projection screen".

Similarly, I'm thinking you want orbital lasers. Besides getting rid of atmospheric scatter -- well, except for what is reflected back from he moon, you could avoid some other problems.

Like possibly incinerating any aircraft or birds that fly over the beams. And bringing down the wrath of that whole Global Warming gang, cuz I also imagine that passing the beams through the atmosphere would involve some heating, very minor I'm sure.

And I would like to see some kind of animation, not just still images. You can have early-evning family-friendly Disneyesque animation (remember The Sorcerer's Apprentice?), and late-night adult porn. If you can figure out a scheme where you need special glasses to see it, you might get into pay-per view.

You might be able to get the Defense Department or the CIA to underwrite the whole thing. I'm pretty sure that with powerful lasers like you would need to do this, if you could spin the orbital lasers around you could do interesting things to the earth's surface too.

[GuanoLad]

...aside from its convexity, or concavity, whichever -- I can never keep them straight.
Convex.

Think of the "cave" part of concave to keep things straight.

[KneadToKnow]

And just to add another "bad idea" comment to the mix: How soon after someone figures out how to display the Pizza Hut logo on the moon is it before someone else figures out how to display "Hello, world!," "Surrender Dorothy," or a swastika?

[Bryan Ekers]

And just to add another "bad idea" comment to the mix: How soon after someone figures out how to display the Pizza Hut logo on the moon is it before someone else figures out how to display "Hello, world!," "Surrender Dorothy," or a swastika?
Well, the moral issues are best left to GD. I started the thread here in GQ to address only the technical/engineering issues.

Well, and to joke around a bit.

[Malacandra]

"Go out into your back garden," Gersen said. "There's a great Darsh face hanging over the garden wall."

[Colophon]

Actually, my first thought was about how lousy a reflective surface the moon would be...
Yes, I've heard that the albedo (reflectivity) of the moon is about the same as that of an asphalt parking lot. Hard to believe, when you see a big white full moon, but that's what they say.

And in fact, that may be something of a myth (http://jeff.medkeff.com/astro/lunar/obs_tech/albedo.htm). Interestingly, that link says that the reflectivity is significantly higher than you'd expect when the incoming light is perpendicular to the surface, as tiny natural glass beads in the moondust act as reflectors.

[Mangetout]

...tiny natural glass beads in the moondust...Can I sell these on eBay? (Buyer collection in person only).

[Boyo Jim]

Yes, I've heard that the albedo (reflectivity) of the moon is about the same as that of an asphalt parking lot. Hard to believe, when you see a big white full moon, but that's what they say.

And in fact, that may be something of a myth (http://jeff.medkeff.com/astro/lunar/obs_tech/albedo.htm). Interestingly, that link says that the reflectivity is significantly higher than you'd expect when the incoming light is perpendicular to the surface, as tiny natural glass beads in the moondust act as reflectors.

Interesting. Many actual projection screens are layered with tiny glass beads to increase the image brightness, so maybe the moon is already as good as it can get.

[si_blakely]

Isaac Asimov wrote a short story about someone selling advertising space on Jupiter. Apparently, aliens often came to the outer solar system to admire our gas giants on their way from one place and another, so an alien corporation wanted to project an ad slogan (for some alien equivalent to Pepto Bismol, I think) across the cloud deck. The best part of the story was the title, "Buy Jupiter!"I'm not sure if it was Asimov or Clarke that wrote this one...

An experiment is being run from an orbiting space station (or maybe moonbase) to release a large cloud of reflective plasma that should be visible from earth. Much discussion is held around the advertising (and amusement) potential. The captain is determined to prevent anyone abusing the experiment, but the gas is released in a "familiar wasp waisted bottle" shape, known to be the captains favourite.

Si

[CalMeacham]

I'm not sure if it was Asimov or Clarke that wrote this one...


Asimov wrote vthat particular one -- it's Buy Jupiter, and is in his antholofgy of the same name.


But Clarke also wrote a story about advertising on the moon. A soft drink company had arranged for a scientific experiment (that was supposed to, at one point, provide a luminous glow on the moon) to light up in the shape of their product logo. Clarke doesn't name them, but it's obvious from his description that the culprit was Coca Cola. The story is in one of his anthologies, but I don't recall which one (tales from the White Hart?)



And Heinlein describes advertising on the moon, too. In The Man Who Sold the Moon he has his character walk into the offices of a soft drink company (un-named, but pretty obviously a stand-in for Coke again) wearing a lapel button with their competitor's logo on it -- a circle with 6+ on it. That's pretty obviously supposed to be 7-UP. The character claims the button is the same subjective size as the full moon. IIRC, they never do say if anyone ever puts up a sign for any company on the moon.









Anything's OKAY with me, as long as it's not CHA.


or HA with a bite out of it.

[muldoonthief]

Since we're delving into fiction...

There's an episode (http://www.imdb.com/title/tt0813112/) of The Tick where Chairface Chippendale tries to carve his name into the moon with a laser. Not just illuminate it, he actually carves trenches in the face of the moon. IIRC, he gets as far as the "A" before the Tick manages to stop all that evil. In a nice bit of continuity, the moon with "CHA" on it is seen in several following episodes.

In another episode (http://www.imdb.com/title/tt0723368/), they try to collapse the trenches with explosives, but stop after the "C" when the Tick is blown into deep space.

ETA: Whoops, didn't see Cal's allusion to this when I posted...

[chorpler]

Asimov wrote vthat particular one -- it's Buy Jupiter, and is in his antholofgy of the same name.

I think si_blakely was referring to the story he described when he said he wasn't sure if Asimov or Clarke wrote it.