Enemy Ascension

First of all, how did another AI destroy a starbase without declaring war? I thought any attacks would result in war...

Can you see all five ascension crystals? I think only five are ever spawned, regardless of map size or number of opponents. Are you absolutely sure they don't control any ascension starbases? If you can't actually see them (as in, you revealed them, but they're in the fog of war), there's a chance they rebuilt when you weren't looking.

About the starbase sharing U.P. law, isn't that just for allies? Is there an alliance between that race and one that currently has an ascension starbase? If so, is it possible to instigate a war between them to break the alliance, or do you get some "I can't betray my allies" line? If that's the case, you may have to destroy the ascension base yourself. Oh, and if you go to the foreign relations menu, United Planets tab, you can check all laws currently in effect.

I'm fairly new to this game myself, and I play with ascension off, so this has me stumped. Let us know what happens!

Well, when I play GC2 for a while starbases and ships dissappear.  Usually I can see the resource, and if I mouse over the resource it tells me there is a starbase there.  When I loaded my game back up there was a single ascension resource with one of the enemy AI's starbases in plain sight.  I destroyed it right away, and the countdown stopped.  I still had to pay both other races to go to war, which is very odd, since I know they destroyed the other starbases yesterday. 

Immediately after that I hit the luck jackpot and got the lucky ranger, which basically rolled around wiping modded starbases and whole fleets.  Two races surrendered to me not long after.  With 2/3 of the map it just became a slow steamroll.

Ascension is a victory condition that isn't implemented properly, strongly discouraging the player from attempting it. For one, it takes too damn long to achieve (200 weeks with ALL FIVE chrystals?!, that's over 4 years! Also, if you as the player are in the position to take all five chrystals and either defend them against the onslaught, or even be strong enough to discourage the AI from declaring war, the game should already pretty much be won by any other means. Clearly any player in that situation is already strong enough to go for the much quicker military, technological or diplomatic victories, with a good chance that an influence victory is also an option. This makes Ascension pretty much superfluous, especially because taking a ascension crystals when you aren't at that powerlevel is pretty much political suicide (and still takes too long anyway).

I'm going to have to guess it's hardcoded though, so no chance of modding it into a viable victory condition.

ascension crystal is just another way to troll the AI into declaring war with you. imagine in a galaxy where every race is friendly or close with you, and none of them wants to attack you. you don't have a lot of planet and you direly needs to expand. you know you have high tech and you know that you can roll over any particular AI easily. you also know that if you declare war, other race will think badly of you because you are trying to be a war monger, so what do you do? you have them declare war on YOU! so you can mob the floor with them, and take their planet. at the verge of their losing their last planet or last few planet after you wiped out all their starships, you trade your starships for all their tech. tadar! you are near the verge of winning the game. you just do this with about two more civis and you will be the highest techer in the entire game. at that point, your victory is pretty much assured.