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