<p>This article examines the ethical implications of human space travel through an analysis of Catholic and Islamic perspectives, with particular attention to how both traditions, in contemporary debate, ground human rights in the intrinsic dignity of the human person. While both Catholic social teaching and Islamic ethics have, in different ways, expressed conditional openness toward space exploration—provided that it is clearly oriented toward peaceful purposes and the common good –, this study argues that their explicit commitment to fundamental human rights raises significant challenges to the justification of space missions. The conditions inherent in long-duration space travel—including exposure to extreme risks to life and health, limited or absent access to adequate medical care, the impossibility of guaranteeing a dignified dying process, and the potential instrumentalization of human beings for technological, political or geopolitical objectives—appear to be in tension with core rights emphasized in both traditions, such as the right to life, human dignity and the right not to be subjected to disproportionate danger. Furthermore, the long-term feasibility of sustained human presence beyond Earth may depend on genetic modification, assisted reproduction or other forms of biological intervention aiming to adapt human beings to hostile extraterrestrial environments. From both Catholic and Islamic perspectives, such practices raise serious moral concerns, as they risk undermining the integrity of human nature, the right to be born in accordance with natural and relational forms of reproduction, and the broader duty to protect human life. Moreover, in the context of life in space, it may be difficult to secure what both traditions regard as fundamental human interests, including, for example, the right to a meaningful social life and the right to a dignified death that is neither induced nor hastened due to the absence of adequate medical care. By bringing these considerations together, the article contends that, within Catholic and Islamic human rights frameworks, the ethical legitimacy of human space travel cannot be taken for granted and, rather, requires careful, critical and context-sensitive re-evaluation.</p>