First of all, I would like to say that even these ideas I'm about to put out there are good or bad, either way this game is the jam. Anyways, I think the sandbox/galaxy mode should have maybe like 3 to 4 different types of resources that is required to build certain things. I was thinking maybe each planet has certain types, but certain unique planets has all required resources on it. I also think that those resources should be limited, not too limited, to where down the line we eventually have to branch out to other planets to find more. Another thing, I think there should be trading with other players basically diplomacy. You can either take each other planets by force or just make peace for the time being and trade resources and team up. I personally think this game will be awesome if these ideas was implemented. Either way it goes the game will still be sweet.
Even though you can move between planets in space, this is not a space game like you think it is. Expect it from mods, but not the standard gameplay that uber implements.