Private space travel has finally begun. Humanity is once again setting its sights on the Moon and Mars. The era of "living in space," going farther and staying longer, is becoming more realistic. In space, cosmic radiation, including heavy particles, is abundant. Gravity is extremely weak. While often referred to as "zero gravity," it is more accurately described as "microgravity" that approaches infinitesimal "zero." At Gunma University, there is a researcher dedicated to considering the health of space travelers. His name is Akihisa Takahashi, and he is from the Heavy Ion Medical Center. His expertise lies in radiation biology, and his current research theme is "Does cancer progress faster in space?" He is currently collaborating with the Japan Aerospace Exploration Agency (JAXA) to explore the feasibility of conducting experiments in the Japanese Experiment Module "Kibo" on the International Space Station (ISS).