Astronauts often stay in space for a long time. What harm will it do to their health in the long run?

Astronauts often stay in space for a long time. What harm will it do to their health in the long run? As the only intelligent life body in the universe so far, human physiological functions are deeply and firmly influenced by the earth, including gravity, atmosphere, water, temperature and sunlight felt on the earth. Therefore, when humans (astronauts) leave the earth's environment for a short time and enter space, their bodies will always undergo some subtle temporary changes, and it will take some time to recover after returning to earth. For example, the phenomenon of virtual height, signs of puffiness, physical weakness and so on. The degree of these phenomena is directly proportional to the length of time astronauts stay in space, and the recovery time of their bodies basically follows the above relationship.

At the same time, it will also have a certain relationship with the individual physique of astronauts. To put it bluntly, when you stay in space for a short time, the human body will generally only undergo certain physical changes. This change is reversible and will recover in a short time without substantial changes. The space environment is characterized by microgravity, weightlessness and strong radiation. Adapting to the gravity environment of the earth, there will be some changes in the human body entering space: swollen face, thin legs, osteoporosis and muscle atrophy, physical growth, dizziness and so on. The bones and muscles that exist for defying gravity become "idle" in weightlessness. In order to adapt to the new environment, bone density is decreasing. According to the research of scientists, one month is about 1% loss.

With the passage of time, bone loss can easily lead to fractures. The fiber quality and strength of muscles will also decline, and the stronger the person, the more severe the decline. Young people in their thirties live in space for a period of time, and when they return to the earth, their muscles are as good as those of people in their seventies and eighties. People with mild symptoms can't walk steadily, and when they are serious, they can't walk at all, and someone has to carry them. Life lies in exercise. Astronauts can keep their bones, muscles and cardiovascular functions through exercise in space, and they can almost recover after returning to the ground for more than a month. The serious problem is osteoporosis, which will take several years.