Human Physiology in Spaceflight and Looking to the Future

Humans have traveled to and inhabited space for 60 years with 2025 marking the International Space Stations (ISS) 25th anniversary of continuous occupation of humans in space. In 2030 the ISS will be de-orbited and commercial space stations are currently building to ISS-like capabilities with the goal of maintaining human presence in space. NASA and commercial spaceflight visions for the future include maintaining human presence in low Earth orbits and traveling to and living on exploration destinations such as the moon and Mars. Goals for future human exploration depends on the ability to protect astronauts’ health and safety for performance of Extravehicular Activity (EVA), in both 0-G and during ambulation in partial gravity, and to allow astronauts to safely egress from vehicles in a variety of landing scenarios, including water landing upon return to Earth and planetary or lunar landings. Prolonged exposure to microgravity results in a myriad of diminished physiological capabilities such decreased exercise tolerance, cardiac and sensorimotor function, bone mineral density, and muscle mass and strength. For over 50 years exercise has been the primary countermeasure against the physiologic losses in these systems during spaceflight; however, as spaceflight progresses towards longer exploration missions and vehicles with less volume compared to ISS, countermeasures will need to be optimized to protect crew health and performance across all organ systems over the course of exploration missions. This will require a much more detailed understanding of the effects of spaceflight on human physiology, starting at the cellular level. To that end, there are technically excellent and innovative research experiments on ISS aimed at understanding stem cell proliferation and differentiation in humans and cell cultures, regenerative medicine for disease modeling and pharmaceutical testing, and 3D bioprinting of tissue structures. While the microgravity research in this biotechnology area is in its infancy, results have shown remarkably rapid progress related to disease treatment on Earth and will inform new and innovative countermeasures for human space exploration. As the low Earth orbit science platform transitions from ISS to commercial platforms, it is critical that these platforms, together with governmental organizations, continue to support scientists to enable future exploration goals, new discoveries for benefits of human health and disease treatment on Earth, and even developing a scalable biomanufacturing based commercial economy in low Earth orbit. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.