The one thing that can fix the problem of
grainy resolution is
multiple
pictures. If your super spiffy spy
satellite grabs 5 images, 1 second apart, their
pixels will be not be completely
aligned with each other (think of two
grids
superimposed with some
rotation and
offsetting). I'm sure you could
interpolate the subtle differences;
probably a decent way would be to construct a higher
resolution image,
and precisely determine the alignment/rotation/stretching of each original image (the hard part). Then, you would
find each of the high-resolution
pixels based on the average of all the larger
pixels that overlap the that place.
I wildly guess that you could at maximum quadruple
the number of pixels (double each axis) with this technique (requiring, say, 8 images), and maybe quadruple that using
image sharpening tweaks (i.e. compensating for the effects of finer pixels you already know). So, my wild
guesses say you could get 2 cm resolution from
10 cm pictures, perhaps enough to read a plate, but I think I'm overestimating this method's ability.
Anyway, the atmosphere would probably interfere in some nasty way.