Interest in space travel has increased since SpaceX’s first commercial launch to the International Space Station in May 2020 and with efforts to send humans to Mars. Jim Bagian, MD, a physician-astronaut who logged 337 hours in space between 1989 and 1991, is director of the Center for Healthcare Engineering and Patient Safety at the University of Michigan and discusses the effects of space travel on the human body and physiologic readjustments on return to earth. Related Content: Do Apollo Astronaut Deaths Shine a Light on Deep Space Radiation and Cardiovascular Disease?