Parallels

I'm a bit confused about the Cardassian's plan to use the telescope thingie as a spy device against the Federation. I mean, it's a Federation installation. It presumably sends data to Starfleet all the time. Do the Cardassians really think that when it stops sending information, Starfleet will just shrug its shoulders and forget about it? Of course not! They'll send a ship to investigate, and the Cardassians will be caught in the act - which is exactly what happened. It would make much more sense for the Cardassians to just blow the thing up and make a hasty exit, then deny all knowledge afterwards.

At least one crew of an alternative Enterprise-D die when there ship explodes. An alternate version of Geordi is killed in one of the parallel worlds.