Yeah I also thought it was odd for them to end-up in Aridia, I figure they would have landed somewhere in Draconia. I guess we can only assume that each dome had a way for ships to enter/exit but only two had working shuttles.
Thoul wrote: The thing I dislike the most about Sean's path is Ayn and Thea's fate. There was no reason for them to stay behind. The shuttle holds at least five people, so they could have evacuated as well.
Although it's not "official", some of the notes from Toyo Ozaki have Thea becoming very frail after Sean was born. If she was too weak to flee quickly, or already near death
, then I can see them staying behind. It may also have been an act of nobility, they were the rulers and weren't going to abandon their doomed people.