A group of volunteers is spending two months lying in bed—with their feet up and one shoulder always touching the mattress—even while eating, showering, and using the toilet. But why? This extreme bedrest study is helping scientists understand how space travel affects the human body and how to keep astronauts healthy on long missions.

Microgravity causes muscle and bone loss, fluid shifts, and other physiological changes similar to those experienced by bedridden patients on Earth. By studying volunteers here on Earth, researchers can develop better countermeasures for astronauts and even improve treatments for medical conditions like osteoporosis.

In this study, participants are divided into three groups: one stays in bed with no exercise, another cycles in bed to mimic astronaut workouts, and a third cycles while being spun in a centrifuge to simulate artificial gravity. Scientists hope artificial gravity could become a key tool in protecting astronauts during deep-space missions.