What will happen to astronauts who have worked in the space station for a long time?

Recent studies have shown that if you live in space for a long time, venous blood will flow backwards, which will not only affect the deposition of calcium in bones and the possibility of cancer, but also lead to an increase in the incidence of jugular vein thrombosis. Generally speaking, it is not suitable for human beings to live in space for a long time.

Modern astronauts are the executors of space missions, but they are also "mice" to some extent. Because no human beings have lived in space all their lives, there is still a lack of corresponding data on what impact the space environment will have on the human body. At present, the astronauts who have lived in space for the longest time are Americans, but they have only stayed in space for about two years, which is only a few tenths of the normal life span of human beings. There are some differences between space environment and land environment, mainly microgravity and cosmic high radiation.

Because people orbit the earth with spacecraft such as space station, and the gravity of the earth also provides centripetal force for people to orbit the earth, the gravity factor suffered by people in space is very weak; The influence of cosmic rays is mainly due to the absence of the earth's atmosphere and magnetic field. Because of the gravity image, the mass of the earth's atmosphere is mostly concentrated in the range of 10 km from the ground, and the magnetic field near the ground is stronger, so people in spacecraft have to bear stronger cosmic radiation.

The space environment has changed people in the following aspects: First, the microgravity of the space environment is not conducive to the deposition of calcium in people's bones, and because of the lack of gravity images, people can easily do all kinds of things in space, and their bones and muscles can't be exercised, so there will be short-term head enlargement, skeletal muscle fatigue and other adverse effects, which is also the reason why astronauts need to be carried away in a chair after returning to Earth for a period of time.

Second, because there is stronger cosmic radiation in the space environment, it also affects human genetic material and human health. NASA analyzed the genes of a pair of identical twins. One of the two brothers is a NASA ground worker and the other is an astronaut. They have been flying in space for several months. After genetic testing, NASA found that the epigenetics (gene expression after A-level transformation) of the astronaut's brother had changed greatly, and the probability of developing cancer in the future increased.

Third, the impact on reproduction. The development of fertilized eggs in mammals is particularly complicated, because the history of mammals appearing on the earth is relatively short and the development process of fertilized eggs is more complicated. So far, human beings have realized that fertilized eggs of fish and amphibians develop in space, while fertilized eggs of mammals cannot develop in space. So far, the best result is the domestic practice 10, which realizes the development process of mouse fertilized eggs from one cell to two cells and even early embryos (32-cell blastocysts).

Fourth, the microgravity environment affects people's blood flow. NASA scholars found that the blood reflux and thrombosis in astronauts' necks increased. Vena is blood that flows back after material exchange. The wall of venous blood vessels is very thin and does not have the ability to beat. But in evolution, venous valves have been formed in veins, a special structure that relies on gravity to avoid blood backflow. In space, there is no pressure difference between different parts of the human body (the pressure of liquid is related to the depth density of liquid, etc. ), and the return of venous blood is more complicated than on the earth, and it is easier to form a vortex in places such as venous valves, which is more likely to cause blood cell fragments to start the coagulation process, leading to an increase in the probability of venous thrombosis.

The effects listed here are only familiar and determined by scientists. After all, the data of mammals from fertilized eggs to old age have not yet been realized, so it is difficult to determine the impact of living in space for a lifetime.