At the beginning of Titan the astronauts and the folks back on Earth agree that "Themis" fits the profile of generation ship. Now I usually abhor the idea of a generation ship,it means perhaps millions of lives lived in a tin can. However, the dimensions of Gaea are large enough to like life interesting even for the majority adventurous persons. If you're familiar with Gaea's dimensions, do you agree? Good image of Gaea with size comparisons. The premise will that the people in the control hub, the center of the ship, have decided that they don't want to end the trip as it means they'd have to give up their privileged positions. The ship's computers, without the knowledge of the Control faction, recruit people from the wheel to get to the hub and help the ship complete its mission. Well, most of the ship's computers, that is.