This article examines some selected ethical issues in human space missions including human missions to Mars, particularly the idea of a space refuge, the scientific value of space exploration, and the possibility of human gene editing for deep-space travel. Each of these issues may be used either to support or to criticize human space missions. We conclude that while these issues are complex and context-dependent, there appear to be no overwhelming obstacles such as cost effectiveness, threats to human life or (...) protection of pristine space objects, to sending humans to space and to colonize space. The article argues for the rationality of the idea of a space refuge and the defensibility of the idea of human enhancement applied to future deep-space astronauts. (shrink)