Narrative review of the physiological challenges and health impacts of human spaceflight

Space exploration presents significant and unique risks to human health due to the harsh environment beyond Earth’s atmosphere. This narrative review synthesizes current knowledge on the primary physiological and psychological challenges faced by astronauts. It focuses on the impacts of space radiation, microgravity, isolation and confinement, distance from Earth, and closed-loop environments on human systems, including bone integrity, cardiovascular and pulmonary function, neurological stability, metabolism, and immune response. The primary objective is to consolidate evidence on these health hazards and to examine the effectiveness of proposed and implemented countermeasures developed to mitigate them, thereby informing strategies for safer, long-duration spaceflight. The methodology involved a comprehensive literature search across databases, including PubMed, Scopus, NASA’s Technical Reports Server, Web of Science, and Google Scholar. Key search terms encompassed “Spaceflight health effects,” “Microgravity Physiology,” “Space Radiation,” and “Countermeasures space exploration.” Peer-reviewed original research and review articles published primarily between 2000 and 2022 were included. From an initial pool of 110 articles, 50 were selected for full-text review based on relevance and quality. The results were synthesized into key health domains, detailing specific impacts and corresponding interventions. Major findings include a 1–1.5% monthly loss of bone mineral density, significant immune function suppression, increased radiation-induced DNA damage and cataract risk, and a high prevalence of orthostatic intolerance and neurological disturbances upon return to gravity. Effective countermeasures highlighted include advanced resistive exercise, pharmacological agents like bisphosphonates, improved radiation shielding, structured psychological support, telemedicine, and optimized nutritional protocols. In conclusion, while human spaceflight poses formidable health challenges, ongoing research has yielded substantial progress in developing multidisciplinary countermeasures. These findings are critical for ensuring astronaut safety and mission success on future deep-space expeditions. Furthermore, this research yields valuable insights with terrestrial applications, enhancing our understanding of human physiology, disuse osteoporosis, immune function, and adaptation to extreme environments.