Stem cell health in space matters for astronaut health and cancer research. Jessica Pham, UC San Diego, explains how spaceflight shapes normal hematopoietic stem cells and cancer stem cells through nano bioreactor studies, astronaut blood analysis, and tumor organoid work in low-Earth orbit. Pham examines increased cycling and reduced dormancy in space, reduced self-renewal after return, and ongoing research on cancer stem cells and their microenvironment, helping clarify how stem cells respond to spaceflight. This work helps explain how space conditions may change stem cell fitness over time and points toward a better understanding of astronaut health, long-duration missions, and cancer stem cell behavior. Series: "Stem Cell Channel" [Health and Medicine] [Science] [Show ID: 41477]