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Laser writing on the moon
I thought I saw recently somewhere a plan to use a laser to put ads on the
moon. Is that really possible? Seems like the power levels required would be prohibitive, or at least dangerous to anything passing through the beam. Should some group decide to such a thing, I wonder how hard it would be to find the source of the laser? -- ************************************************** ************ Mike Ross, PE * 20+ yrs at JSC in Shuttle & ISS robotics Opinions expressed herein would probably appall NASA ************************************************** ************ |
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Laser writing on the moon
On Apr 1, 2:05 pm, Mike Ross
wrote: I thought I saw recently somewhere a plan to use a laser to put ads on the moon. Is that really possible? Seems like the power levels required would be prohibitive, or at least dangerous to anything passing through the beam. Should some group decide to such a thing, I wonder how hard it would be to find the source of the laser? -- ************************************************** ************ Mike Ross, PE * 20+ yrs at JSC in Shuttle & ISS robotics Opinions expressed herein would probably appall NASA ************************************************** ************ Not a power or safety problem if such photons were transmitted from within the moon's L1, roughly a little better than 58,000 km away from the moon. However, that moon is nearly as dark as coal, most of it covered in a deep and crystal dry layer of fluffy and electrostatic charged dust (hardly reflective in the visual spectrum, but fairly IR good to go), so that you'd need nearly 10 fold as much laser cannon beam energy as you'd think. .. - Brad Guth |
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Laser writing on the moon
Mike Ross wrote in
: I thought I saw recently somewhere a plan to use a laser to put ads on the moon. Is that really possible? Seems like the power levels required would be prohibitive, or at least dangerous to anything passing through the beam. Should some group decide to such a thing, I wonder how hard it would be to find the source of the laser? Given the low albedo, the size of the area that'd need to be illuminated and distance of the target...yeah. Serious power. Got to keep the beam from spreading too much and the earth's atmosphere might tend to scatter the beam a bit, too. Even so, surely someone's tried this...? --Damon |
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Laser writing on the moon
Damon Hill writes:
Mike Ross wrote in : I thought I saw recently somewhere a plan to use a laser to put ads on the moon. Is that really possible? Seems like the power levels required would be prohibitive, or at least dangerous to anything passing through the beam. Should some group decide to such a thing, I wonder how hard it would be to find the source of the laser? Given the low albedo, the size of the area that'd need to be illuminated and distance of the target...yeah. Serious power. Got to keep the beam from spreading too much and the earth's atmosphere might tend to scatter the beam a bit, too. Even so, surely someone's tried this...? An article for Nature that I dug up when this was discussed a couple weeks back on rec.arts.sf.written claimed that the signal loss on a laser bouncing from Earth, to the reflectors on the Moon, back to the Earth, is something like 10^{-21} -- and remember, that's to the spots on the moon designed to reflect as perfectly for the mass as humans could manage, circa 1970. I'm sure I can find it again, but it wasn't a particularly tricky Google search for it. Considering that most of the Moon has a vastly lower albedo, and that you would need to send up enough light that what's reflected stands out against the full moon's intensity -- and to complicate things, that the logo is a light green, which is harder to read on the basically-white background than, say, red would be -- and ... I don't have a quick way to calculate what power is needed, but feel safe to say nobody's got a laser that'll do that. -- Joseph Nebus ------------------------------------------------------------------------------ |
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Laser writing on the moon
On Apr 1, 10:15 pm, Damon Hill wrote:
Mike Ross wrote m: I thought I saw recently somewhere a plan to use a laser to put ads on the moon. Is that really possible? Seems like the power levels required would be prohibitive, or at least dangerous to anything passing through the beam. Should some group decide to such a thing, I wonder how hard it would be to find the source of the laser? Given the low albedo, the size of the area that'd need to be illuminated and distance of the target...yeah. Serious power. Got to keep the beam from spreading too much and the earth's atmosphere might tend to scatter the beam a bit, too. Even so, surely someone's tried this...? --Damon What's your dumbfounded problem? There's not a beam spreading or all that much energy demand if transmitted from the moon's L1. .. - Brad Guth |
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Laser writing on the moon
On Apr 2, 9:00 am, (Joseph Nebus) wrote:
Damon Hill writes: Mike Ross wrote in : I thought I saw recently somewhere a plan to use a laser to put ads on the moon. Is that really possible? Seems like the power levels required would be prohibitive, or at least dangerous to anything passing through the beam. Should some group decide to such a thing, I wonder how hard it would be to find the source of the laser? Given the low albedo, the size of the area that'd need to be illuminated and distance of the target...yeah. Serious power. Got to keep the beam from spreading too much and the earth's atmosphere might tend to scatter the beam a bit, too. Even so, surely someone's tried this...? An article for Nature that I dug up when this was discussed a couple weeks back on rec.arts.sf.written claimed that the signal loss on a laser bouncing from Earth, to the reflectors on the Moon, back to the Earth, is something like 10^{-21} -- and remember, that's to the spots on the moon designed to reflect as perfectly for the mass as humans could manage, circa 1970. I'm sure I can find it again, but it wasn't a particularly tricky Google search for it. Considering that most of the Moon has a vastly lower albedo, and that you would need to send up enough light that what's reflected stands out against the full moon's intensity -- and to complicate things, that the logo is a light green, which is harder to read on the basically-white background than, say, red would be -- and ... I don't have a quick way to calculate what power is needed, but feel safe to say nobody's got a laser that'll do that. -- Joseph Nebus ------------------------------------------------------------------------------ Then simply laser illuminate upon the physically dark moon as of otherwise being earthshine dark, and otherwise by way of simply using the moon's L1 as the efficient station-keeping location for those laser cannons, and of easily creating every viable color you'd like (including UV and IR if you'd like). .. - Brad Guth |
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Laser writing on the moon
Im sure there is not a single laser that could undertake this task, but how
about hundreds or even thousands of lasers, all working in sync might work. Dan. "BradGuth" wrote in message ... On Apr 1, 10:15 pm, Damon Hill wrote: Mike Ross wrote m: I thought I saw recently somewhere a plan to use a laser to put ads on the moon. Is that really possible? Seems like the power levels required would be prohibitive, or at least dangerous to anything passing through the beam. Should some group decide to such a thing, I wonder how hard it would be to find the source of the laser? Given the low albedo, the size of the area that'd need to be illuminated and distance of the target...yeah. Serious power. Got to keep the beam from spreading too much and the earth's atmosphere might tend to scatter the beam a bit, too. Even so, surely someone's tried this...? --Damon What's your dumbfounded problem? There's not a beam spreading or all that much energy demand if transmitted from the moon's L1. . - Brad Guth |
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Laser writing on the moon
On Apr 9, 6:47 pm, "NTL Newsgroups" wrote:
Im sure there is not a single laser that could undertake this task, but how about hundreds or even thousands of lasers, all working in sync might work. Dan. As transmitted from the moon's L1 that's roughly 58,000 km away from the moon, and depending on how large of pattern gets projected onto the dark earthshine illuminated moon (say not more than illuminating a 1,000 km diameter), there is sufficient laser cannon capability if an array of 10 such commercial laser projections were utilized . The reflected light of the visual spectrum would still be fairly dim to the naked eye, unless IR counts, because IR reflects off the moon at the albedo efficiency of 33 to 50%. .. - Brad Guth |
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Laser writing on the moon
NTL Newsgroups wrote: Im sure there is not a single laser that could undertake this task, but how about hundreds or even thousands of lasers, all working in sync might work. Dan. Several years back somebody came up with a scheme where as many people around the world as possible were supposed to aim their laser pointers at the Moon simultaneously. It wouldn't have worked, but it was kind of a fun idea. Pat |
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Laser writing on the moon
On Apr 10, 12:04 am, Pat Flannery wrote:
NTL Newsgroups wrote: Im sure there is not a single laser that could undertake this task, but how about hundreds or even thousands of lasers, all working in sync might work. Dan. Several years back somebody came up with a scheme where as many people around the world as possible were supposed to aim their laser pointers at the Moon simultaneously. It wouldn't have worked, but it was kind of a fun idea. Pat A sufficient battery or array of green power lasers in the commercial range of several watts each, as such could rather easily make a sustained 100 km diameter spot on the physically dark lunar surface visible to the naked human eye, although red lasers would actually reflect more efficiently. Laser tracking would be most difficult for the majority of the public armatures, but not insurmountable. Using 1/10 second pulsed laser shots at much greater intensity would be more doable. .. - Brad Guth |
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