You have just met an alien from another planet and he wishes to take?
As much as i would want to go, i am not the best candidate. I would nominate Neil deGrasse Tyson, he does so well representing science, with his intellect and patience that i think he would make a good diplomat that could grasp better than most what he sees on the trip. And it was his dead masters dream (sagan) to venture to the stars and connect with life elsewhere, so deGrasse will take extra care to make sure it is handled well.