On Sat, 27 Jun 2009 23:54:14 -0700 (PDT), Robert Clark
wrote:

I had been thinking about methods of high data rate transmission in
regards to getting *video* transmissions from Mars orbiter missions. I
was irritated by the spotty coverage of the Mars surface at the best
resolutions so I wanted to send real-time *continuous* imaging back to
Earth receiving stations at the highest imaging resolutions.

A curious distinction in this "continuous." Direct Current
transmission from Mars? I think not. Anything else is rather
conventional.

This
would require very high transmission rates, much higher than what is
currently used.

"Continuous" is not distinctive to rate except at DC. Grab both sides
of conventional 120VAC from any wall socket, and it will seem
distinctly continuous - boosting it 1 THz wouldn't bring any different
sensation.

The idea would be to use light transmissions but only of the on-off
variety.

Rates, and on-off have departed the realm of "continuous."

You would use a large surface, many meters across, capable of
being alternatively lit up and darkened.

This is entirely unrelated to "continuous" rates or modes of
transmission. In and of itself, in regards to establishing remote
communications at light wavelengths, it is guilding the lily and
painting the rose.

There are computer chips of
course capable of operating at Ghz rates.
How that relates to:
This would determine if the
large surface was lit up or not electrically, possibly by using a
material whose reflective properties can be changed electrically.
is bordering on stream-of-consciousness rambling.

I actually wanted to use separate,
say, squares on the reflecting surface that could be put separately in
the on-off position to increase the information transmission rate.

There is no causal correlation between many surfaces and rate. This
is merely the substitution of complexity for the appearance of deep
consideration (which it is not).

This is why I wanted to use light rather
than radio for this since the larger wavelengths in radio would make
the reflecting surface impractically large for diffraction limited
resolution.

You are simply limited in your perception of what RF and Light means.
If one suffers for wavelength, then they both do.

Even with light you couldn't do this with a single telescope.

Sounds like an artificial objection. Have you tried thinking in terms
of a power budget?

They would have to be widely separated.
Does not come naturally as a solution from the rather diaphonous
problem put forward to this point, and the following is not a reason:
Combining the signals from widely
separated scopes is common in radio astronomy but is not nearly as
successful in optical astronomy. That is because the light wavelengths
are so much smaller and you would have to have nanoscale accuracy in
positioning the widely separate mirrors in relationship to each other.
This is problem of degree, one which you painted yourself into a
corner with. Further, it doesn't necessarily follow one from the
other.

However, in the case of just detecting an on-off signal this shouldn't
be as big of a problem as you're not trying to form a usable image,
but only trying to see if a particular location is on or off. You
would need though highly accurate timing synchrony between the
separate scopes, within nanoseconds, to be sure they are detecting the
same on-off square. Note also here that the shifting in the image due
to atmospheric distortion very definitely would be bad for using
ground based scopes.

This is, based on your own objections, rather whipsawed by the
application of the term "nano." Nanoseconds and nanometers are not on
the balance to the solution of your problem. If you had nanometer
issues optically, they are not solved within nanoseconds simply
because they are not forming an image (which is a poor metaphor
because if fails with its own application).

moon advertising.
put a billboard on the moon.
http://www.halfbakery.com/idea/moon_20advertising

Half backed? It is undercooked by half that again.

Let's consider: To obtain a sufficient contrast ratio, the light
would have to exceed the brilliance of the sun.

Did I mention a power budget?

The rest of this hardly borders on novely so much as fantasy. Keep
that to the appropriate groups.

73's
Richard Clark, KB7QHC