The amount of money involved in bluescreening the starfield would be
prohibitive. We spend a LOT of time out there, and you have to matte this
stuff in frame by frame, and at 24 frames per second, even with digital
cutting, you're looking at a *massive* amount of rendering time.
We could do it...but it would tie up our compositing and rendering
machines so we couldn't do much of anything *else*....and I'll swap one nifty
shadow fighter/collision shot for a whole SEASON of moving stars.