This paper will explore the processes by which astronaut identities are transformed in the extreme environment of space. Drawing on terrestrial migration theories, I will explore how astronauts and analogue astronauts define and modify “the self” while alienated from their territories and their planet. I will anthropologically frame these extreme journeys as ‘rituals of transformation’ and ‘rites of passage’, in which cohorts experience liminality and communitas, and are thereby reconstructed in themselves. This is inspired by cosmonaut Lebedev’s self-observation, “no longer earthling,” and Leninger’s, “untranslatable to oneself.” Building on pilot fieldwork conducted on the MEILI-I Space Health Research analogue mission, in which I was a participant observer and employed extensive collaborative ethnographic techniques, I will explore findings and (crucially) tie them back to terrestrial migration. The paper is meant to open a conversation on how extraterrestrial migration can inform terrestrial migration, and vice versa. What can we learn from extreme journeys on Earth as we make plans to send astronauts to space stations, the Moon, and Mars? Reciprocally, how can we look back from our journeys in space to gain a new perspective of journeys on Earth?