After the astronauts return to the ground, they are usually lifted out of the return capsule by the staff. Why does an astronaut with such a strong body need to be lifted out?

Astronauts Jing Haipeng and Chen Dong on the Shenzhou 11 mission returned smoothly

In the space mission, there are mainly the following aspects:

1. Space Adaptation Syndrome

After entering space, everything will float under weightlessness, and people are no exception. This will cause the astronauts to be unable to distinguish up, down, front, back, left, right, and the vestibular system of the brain and related nerves will be disordered. The obvious manifestation is uncontrollable nausea (similar to motion sickness and seasickness). Every astronaut has undergone extremely hard training to overcome these physiological reactions, but the process of returning to Earth takes only half an hour, which is far from enough for the brain to adjust to the space position and the influence of gravity. Their brains still think that they are in In a state of weightlessness that is completely out of control, people stand up like drunk, shaking and losing their direction.

2. Loss of bone and muscle mass

After the long-term expectation in space, the internal changes of the body are mainly reflected in the bones and muscles. Due to the lack of movement and gravity, the body has a very small burden. In space, the human body will rapidly lose these two important body structures. Bone loss is very dangerous. After returning to the surface, the human body not only has to bear its own weight again, but also bear the cabin suit with a total weight of about 20 kilograms. If the astronauts exercise vigorously, they will easily fracture. So getting out of the cabin by oneself is a life-threatening one, even the people who carried them out have to be especially careful, after all, the once iron men are temporarily "glass men" after they come back.

3. Body fluid reset

When on the surface of the earth, the body fluid will be more concentrated in the lower part of the body under the action of gravity. But in space, these body fluids tend to be evenly distributed throughout the body. The most obvious change is the increase in body fluids in the upper limbs, which can be seen on the face.

航天员景海鹏出征前照片

Photo taken by astronaut Jing Haipeng Space Institute

This body fluid change will have a great impact on the human body, especially on the heart and brain blood vessels. The pressure in the brain will increase a lot, and blood pressure will also increase. The pressure on the eyeball will increase, vision will be affected, and the taste and smell systems will be greatly disturbed. Both body fluid circulation and blood circulation are forcibly adjusted by the body to adapt to this change. Back on the surface, these circulatory systems cannot be restored in a short period of time, which is why all astronauts have to lie back, on the one hand to adapt to overweight and vibration shock, on the other hand to adapt to the huge changes in body fluids and blood circulation.

In this case, we must do everything possible to reduce the body's movement, avoid aggravating the burden on the body's various circulatory systems, and make the body adapt quickly.

4. The time to return to Earth is short

Generally, when a spacecraft descends to about 80 kilometers, due to the high speed and atmospheric density of the spacecraft, the spacecraft begins to heat up violently, shakes violently, and the effect of gravity also begins to appear (overweight phenomenon appears). Moreover, due to the ionization effect of the high temperature of the air, the spacecraft loses contact with the communication system and enters the black barrier area. This process will last 10-15 minutes, and it will take another 10-15 minutes to descend back to the earth. Therefore, astronauts only have at most 30 minutes to quickly adapt to gravity, not to mention that they are still overweight in the black barrier area in the first 15 minutes, which has a huge impact on the already fragile astronauts.

Therefore, the return of astronauts from all over the world, especially after they have stayed in space for a long time, are all carried out.