This looks like a good variant. There are always more ? counters than ? spaces though so it's possible that the Wormhole will be left out of the game. Was this the intent or is the Wormhole always in the game? It seems to me that the possibility of it not being in the game is better; otherwise, when all but one ? counter are revealed all players will know where the wormhole is - which isn't as fun/logical. I think there should always be a possibility that this culture will not be in the game - in this case it wouldn't be necessary to sort out the Wormhole from the other counters when placing a ? counter in that system.

Having an orbital around the planet as large as those around the stars is a bit odd. Not sure how that could be explained. Perhaps all the spaces should be penalty ovals - some sort of shield defense system the player's ship must navigate thus slowing its approach?