Edit: Y'kmow, now that I'm jostling the old memory chips, I do have a vague recollection of a rare black and white photo many years ago (the kids call it "grayscale" now). I'm thinking it may have been in Stephen Whitfield's "The Making of Star Trek", of a view straight up the tube taken from the bottom. There was some kind of greeble all the way at the top and some kind of glow beyond it. My memory is very hazy, but it always stuck with me and was rattling around out there. My copy of that book is in a box somewhere, and I'm hoping someone here has a copy handy and can see what I'm talking about.