I didn't know you could leave the UP...How?
On the United Planets subscreen of the Foreign Stats screen, in the upper right, there is a button that says "Leave U.P.". You can't ever get back in, though. EVER. And it means you can't have trade routes anymore.
I would agree that Terror Stars should be affected by the U.P. starbase module vote.
Not to get off topic, but while we're on the subject of Terror Stars, why is it that you can use a single Terror Star to destroy multiple systems? Sure, it takes a while, but it means you don't need to build more. It doesn't make much sense from any point of view-I mean, they blow up the star, the planets, all the ships around the star, the asteroids even, if I remember correctly (though since everything is "converted" into asteroids, that doesn't matter too much), the resources, the anomalies (even if it's a wormhole, which is moderately humorous), yet they survive the blast?
I'm not sure how much of a difference it would make-there was one game that I got bored of and created enough Terror Stars to take out the Drengin's last system as well as all eight of my systems in the same turn-and even though I destroyed them first, I wound up getting a Defeat message for destroying my own homeworld with a Terror Star. However, I would still suggest that Terror Stars be consumed/destroyed upon use. A limit of one active per civilization might be a good idea, too.
Maybe not the best place to voice my thoughts, but still somewhat ontopic.