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?
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Mike Ross, PE * 20+ yrs at JSC in Shuttle & ISS robotics
Opinions expressed herein would probably appall NASA
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