Space exploration and astrobiology (the study of the “origin, extent, and future of life” in the universe1) are subjects which raise important ethical questions. So far, in our limited experience in space, we only know of the existence of life and intelligence on Earth. Apart from our home planet, in outer space, we only know of the existence of non-life; though the potential for the evolution of life and even intelligent life seems probable given the size of the universe. As humans continue to explore space we should be ready for the ethical dilemmas we may find there. In our planning, right here and now, we are already confronted by questions of how to act. Should we explore space at all, or instead concentrate on solving problems on Earth? Should we put landers on other worlds, knowing that we will contaminate them with microbes from Earth? Should we mine the Moon, asteroids, and other planets? Should we alter the environment of Mars and bring life there from Earth? All of these questions are “should” questions, ones which require deliberation and judgment of potential courses of action. And so these questions are not just questions of science, politics, or economics, they are questions of ethics.