Through human exploration, the extraterrestrial space becomes more and more the legitimate subject of an anthropological debate. Regarding the rationality of moral actions related to space exploration, the purpose of this article is to compare two ethical approaches: generalism and particularism. Moral generalism claims that the rational authority of morality is founded on the affirmation that a moral principle exists in order to ensure that a moral reason in a particular case is automatically a reason in all future particular cases. If its mere application determines the moral statute of any conceivable action then it should be capable of functioning as an action guide in any new case. Unfortunately, ethical-regulative presumptions cannot explain the moral statute of any new action and especially cannot provide guidance in exceptional cases. This is precisely the peculiarity of any action of exploring. Instead, moral particularism provides us with an alternative epistemological position: instead of conforming to a series of principles, our actions are justified by those moral aspects of a situation which are self-evident, aspects which do not possess the same moral importance in each new situation that may arise. Because of the multitude of morally relevant aspects of environmental action, in order to tackle complicated or completely new ethical issues we are more in need of actual moral discernment than of ethical-regulative presumptions. This kind of approach is more adapted to the extremely complex and unpredictable (from a normative and evaluative standpoint) character of the exploration and exploitation of outer space.