I use a track ball mouse and aside from the initial loading of the game, I cannot zoom out in order to see more of the galaxy than one star system.

I've tried PageUp and PageDown and I've tried mapping PageUp and PageDown to my mouse buttons 4 & 5 (which is what I normally use for scrolling).

I've even tried mapping PageUp and PageDown back to themselves on my keyboard.

This thread may be closed.  I found that I need to press the PageUp or PageDwn ket and hold it for a second for it to initially work on the universescape. Then it works normally afterwards.