If you were wondering if there was enough of it to warrant a specific ethics interest, the answer is yes. NASA has a their first chief of bioethics, Paul Root Wolpe, a medical sociologist and bioethicist who is also the Director of the Center for Ethics at Emory University. Apparently he rules on things that could pertain to labor laws, like health and safety of the astraunauts, who are themselves often subjects of research. Health and Safety laws limit workers exposure to radiation - but how to reconcile that when you are in a spaceship with no way to be less exposed... Very interesting article about this by Claudia Dreifus in the New York Times entitled "Scientist Tackles Ethical Questions of Space Travel".