The increasing human activity in outer space confronts us with two intertwined sets of problems. One is related to possibility of the life elsewhere in the universe, especially the potential existence of alternative, non-terrestrial biospheres, currently under investigation in astrobiology. The hypothetical encounter with such unorthodox forms of life raises questions about what intuitions cultivated by environmental ethics are translatable to such extra-terrestrial contexts: How should an interface between two different biospheres be managed? Should they ever even touch? Simultaneously, one has to be mindful of the second set of problems, related to the constant threat of biological contamination of extra-terrestrial environments, which may corrupt not only chances of actually finding life outside Earth, but also the very integrity of abiotic cosmic environments. For this reason, it is important to develop philosophical and ethical intuitions that may govern responsible conduct of space activities which involve non-human organisms of terrestrial origins (e.g. intentional transport of microorganisms or plants to the Moon for scientific purposes).