I think the answer to this is obvious . . . NO, all the cards go to the discard pile, but the rules on Citadel's card say that you MAY USE this power to activate the citadel cards, so my friend argued that the cards remain, he just couldn't use them.
So which is it? Do Citadel's (the numbers by your planets) stay in place when you lose the Citadel alien card?
Thanks for the help!