This book explores the dynamic interplay between astroparticle and medical physics, emphasizing how these disciplines converge to address challenges in radiation science and its applications. Key topics include space radiation, its implications for human space exploration, and strategies for radiation protection. By assessing health risks and evaluating space radiation sources, the book develops a comprehensive perspective on safeguarding astronauts during missions.Beyond space applications, the book highlights the synergies between radiobiology and the medical use of ionizing radiation, demonstrating how interdisciplinary research fosters innovative approaches to understanding and mitigating radiation effects on biological systems. Lessons drawn from space science are used to inform and enhance medical practice.A case study on the Alpha Magnetic Spectrometer (AMS) research group at the INFN Roma Sapienza division serves as a concrete example of successful interdisciplinary collaboration. It illustrates the value of shared methodologies and technologies, and advocates for the creation of common platforms for radiation measurement and monitoring — tools that can serve both space exploration and medical fields. This book is an essential resource for researchers, professionals, and students in physics, space science, and the medical domain.