Living in space for an extended period of time can have a significant impact on the human body. Research has shown that astronauts in microgravity experience bone and muscle loss, weakened immune systems, and difficulty sleeping. These changes are caused by the body's cells being placed in an unfamiliar environment. NASA's one-year mission is an experiment to see how long-term space flights affect the human body.
Astronaut Scott Kelly collected fluid samples and underwent medical tests throughout his 340-day stay aboard the International Space Station to document these changes. He and his brother Mark also took body samples and underwent medical tests for a year before the space flight, allowing researchers to compare the twins' genes and determine if there is a genetic basis for some of the health effects in space. The lack of gravity in space can cause fluids such as blood to move to the upper body, leading to swelling in the back of the eye and vision problems. Prolonged periods in space can also deregulate the immune system, leaving astronauts vulnerable to pathogens, hypersensitivity, and unwanted autoimmune responses.
In addition, astronauts don't get the same level of exercise as they do on Earth due to the lack of gravity. NASA hopes to find out if their Chibis device has been effective in balancing Kelly's body fluids while he was in space. This will help them adjust their protocols and extend the amount of time humans can spend in space. While Sergei Krikalev holds the record for most days spent in space with 803 days spread over six flights, it is still unknown how long humans can survive in space.
