["Bioethics, Volume 40, Issue 6, Page 589-596, July 2026. ", "\nABSTRACT\nIn this paper, I argue that negative genetic selection should play a significant role in space exploration and colonization, at least until therapeutic gene editing and repair technologies are cheap and effective enough to enable modification of embryos that would otherwise be selected against and discarded. I present two key reasons supporting this claim. First, there are many traits prospective parents have strong reasons to select against in the Earth context despite the lack of the significant environmental pressures present in space, and these reasons are likely to persist in the context of space exploration and colonization. Second, both in general and in the high‐stakes context of space exploration and colonization, negative selection is likely to be desirable to implement. With regard to the latter context, this is because negative selection can help increase the chances of astronaut survival, mission success, and thriving space colonies by ensuring that astronauts do not have certain traits that would negatively impact those chances. For all these reasons, space bioethicists should avoid prematurely ruling out negative selection as a useful and desirable tool for ensuring that future space exploration and colonization missions have maximally effective and healthy crews.\n"]