What happens to your body after a year in space? 🧬 NASA - National Aeronautics and Space Administration’s Twin Study followed astronaut NASA Astronaut Scott Kelly during his year on the ISS while his identical twin, Captain Mark Kelly, stayed on Earth. Led by geneticist Dr. Chris Mason, the study revealed thousands of biological changes, from gene activity to DNA repair. Most returned to normal after landing, but some lasted for months. These insights are key to understanding how space affects