What are the potential effects of long-term space travel on the human body?

Long-term space travel poses several challenges to the human body due to the microgravity environment and exposure to cosmic radiation. Muscle atrophy occurs because, in microgravity, the muscles do not need to work as hard to support the body, leading to a reduction in muscle mass and strength. This condition can significantly affect astronauts' physical capabilities upon their return to Earth.

Vision problems are also a noted concern, as fluid shifts in the body can cause increased pressure on the eyes, leading to changes in vision and even structural changes to the optic nerve.

Changes in the immune system are another vital effect observed in astronauts. Research indicates that space travel can alter immune response, potentially making individuals more susceptible to infections or illnesses.

Understanding these effects is crucial for planning long-duration missions, such as those to Mars or long-term stays on the Moon, as it ensures that adequate countermeasures can be implemented to maintain the health and performance of astronauts during and after their journeys.