Science in Orbit

The ISS hosts hundreds of experiments across biology, physics, materials science, and medicine. Microgravity lets researchers grow protein crystals, study fluid dynamics, and watch flame behavior in ways impossible on Earth. Medical research on bone loss and muscle atrophy directly informs treatments for osteoporosis and aging back on Earth.

One of the most important ISS roles is studying the human body's response to long-duration spaceflight. NASA's Twins Study compared astronaut Scott Kelly, after a year in space, with his identical twin Mark, who stayed on Earth. Researchers tracked changes in his gene expression, immune system, and cognition.