An astronaut is a trained professional who travels into space to conduct research and perform tasks outside of Earth’s atmosphere. They undergo rigorous training to prepare for the physical and mental challenges of space travel, including simulations of weightlessness and learning to operate spacecraft. Astronauts often work on missions aboard spacecraft like the International Space Station (ISS), where they conduct experiments in microgravity. They may also participate in spacewalks, known as extravehicular activities (EVAs), to repair equipment or conduct scientific research outside the spacecraft.