Since the Expedition One launch to the International Space Station (ISS) in 2001 — the first long-duration stay on the orbital construction site — NASA’s Human Health and Performance team has been developing expertise in the planning and provision of medical support to crews staying in our world’s most remote environment. Four times each year, we launch a new team of astronauts and cosmonauts to the ISS, where they will stay for six months to one year, performing engineering tasks, research, maintenance, and upgrades to prepare for future commercial vehicles. During this amount of time, access to medical care is crucial, as altered routines and microgravity have deconditioning effects on crew members’ bone and muscle, fluid distribution, and immune function.