Shenzhou 14th return time has been determined, and is tentatively scheduled to be 19:52~20:22 Beijing time on December 4, but in the end, the exact time of returning to the day shall prevail.
In fact, we have known from the news a few days ago that Shenzhou 14 will land at Dongfeng landing ground at night, and it is currently in the cold winter, and the temperature at the landing ground is as low as minus 20℃ at night, which poses new challenges to the search and rescue work.
However, the search and rescue team has made complete preparations for response. As of the last comprehensive drill for the whole system on December 1, Dongfeng Landing Field has organized many training drills in stages, especially the drill for night search and rescue, which has made breakthrough progress.
For example, the helicopter search and rescue team broke through the key technology of helicopter landing in the Gobi soft sand area at night through 14 night flight training and landing training.
In addition, the ground search and rescue team also conducted a carpet-style survey of the landing area, recorded and sorted out the easy-to-pass trajectory of the vehicle, and prepared for rapid maneuvering at night.
Some people may ask, why does Shenzhou 14 have to return at night? Doesn’t this increase the difficulty of search and rescue?
In fact, the return capsule of is not a matter of course when it returns. If the astronauts want to accurately land in the designated area, the spacecraft needs to reach the appropriate phase and angle to get out of the spacecraft, and this optimal time is not determined at will.
In addition, for the return capsule to return to the earth, there is no difference between day and night, because it is not recognized by the naked eye, but by tracking and positioning systems to determine the location of the return capsule.
. Also, choosing to land at night is also a verification of the search and rescue teams at night during the space station project mission stage. After the normal operation of my country's space station in the future, astronauts will travel to and from the space station and the earth more frequently, and any situation may occur. Our search and rescue teams will also carry out actual night search and rescue operations.
No matter what, the search and rescue work for Shenzhou 14 is ready, as Bian Hancheng, deputy chief designer of the manned aerospace engineering landing system, said: Currently, all search and rescue forces and equipment at Dongfeng landing site are in good condition and are in good condition to perform search and rescue missions.
Despite this, returning to Earth by manned spacecraft is always a process full of dangers and challenges. Shenzhou 14 astronauts have to go through extremely harsh tests from the spacecraft leaving the space station to their safe landing.
So what will the three astronauts go through?
overweight
Return capsule returns to the earth by the friction of the atmosphere to slow down. After the return capsule leaves the space station, it gradually drops from the altitude of the 393-kilometer space station. When the altitude drops by 100 kilometers, it will be affected by the resistance of the atmosphere.
At this time, the speed of the return capsule is about 7 km/sec. It needs to quickly reduce the speed with the help of atmospheric friction resistance, which is equivalent to a speeding car suddenly stepping on the brakes to the bottom, and the astronauts will be subjected to a powerful reverse thrust , which is overweight.
When the Shenzhou 14 astronaut returns to land, they must bear at least 4g of overweight force, which is equivalent to 3 adults pressing on the astronauts.
Fortunately, astronauts have undergone special overweight training and can withstand 8 times gravity. This overweight when they return is a pediatric department for them. If they were ordinary people, they would have been dizzy, has difficulty breathing, and even fainted.
black barrier
Just now we mentioned that the return capsule rushes into the atmosphere at a speed of about 7 km/sec. Friction with the atmosphere at such a high speed will cause an plasma gas layer to be generated around the return capsule, which will shield the electromagnetic wave , causing a "black barrier" to form between the surface of the return capsule and the atmosphere.
During the black barrier, the return capsule will completely lose contact with the ground control center, the astronauts will enter a completely lost contact, and the control center will not catch any signals from the return capsule, and this process will last for 4 to 6 minutes.
During this period, astronauts not only have to endure the physical discomfort caused by overweight, but also have to endure the psychological fear caused by losing contact, which is a huge physical and psychological challenge for their physical and psychological.
impact
After the return capsule enters the black barrier area from a height of 100 kilometers, the signal will not be captured by the control center again until it is 40 kilometers altitude. When it falls to a height of 10 kilometers, the astronauts will have to withstand a huge "impact".
This impact does not mean that the return capsule hits something, but when it is 10 kilometers high from the ground. The umbrella hatch cover of the return capsule will be opened, and the huge slowdown parachute will be opened in turn, which will reduce the landing speed of the return capsule from 200 meters/sec to 60~70 meters/sec.
When the main parachute is opened, the speed of the return capsule will be reduced to 5~6 meters/second. At the moment when the parachute is opened, the astronauts in the return capsule will be subjected to a strong impact.
When the parachute is opened, the return capsule will slowly land until about 1 meter away from the ground, the return capsule's reverse push system will automatically open, allowing the return capsule to softly land.
But even so, astronauts will still be hit to a certain extent, and several impacts may cause harm to their bodies.
Cold
Compared with the summer daytime when the astronauts returned in Shenzhou 13 , the time when the astronauts returned was winter night, the temperature of the Dongfeng landing site would be as low as minus 20℃. This not only brings difficulties to the search and rescue work, but also challenges the astronauts who just returned.
Before the opening of the cabin opens the return capsule, the temperature in the return capsule is relatively stable and warm. However, once the cabin door of the return capsule is opened, the three astronauts will immediately enter a very cold environment.
Of course, the search and rescue team has prepared cold protection materials and will protect the three astronauts as soon as possible to prevent them from suffering from wind and cold, but this is still a big challenge.
adapts to
Shenzhou 14 astronauts who have lived in the space station for 6 months have adapted to the weightless environment in space. Their muscles and tissues have atrophy and partially lost their bones, especially their blood has been reduced.
This has no problem in the environment where loses weight in the space station, but after returning to the earth and returning to the gravity environment, the astronauts' bodies cannot adapt quickly, which will make them feel very uncomfortable.
, especially their , blood pressure is relatively low, and symptoms such as dizziness and dizziness will occur. In addition, the speed of life and death when returning to the ground from space is just experienced, astronauts need a process to adapt to the earth's environment. The mission after returning
is
, just like other astronauts who have just returned, Shenzhou 14 astronauts will take a short rest and adapt at the landing site after leaving the cabin, and will then be transferred to the airport and then returned to Beijing by a special plane. During the transfer, the astronauts will remain in a seat and be carried away by the staff.
This is not because astronauts are playing big names, but because their bodies cannot adapt to the earth's gravity environment for a while, and they have no strength to stand up at all, and the danger of standing up is very high.
After returning to Earth, astronauts cannot go home immediately. They will have to undergo medical isolation for at least two weeks. Astronauts are isolated from , and they are not worried about bringing unknown creatures back from space.
But they just returned from space, and their body's leave-wash system is very weak. Our ordinary cold may cause them to get seriously ill. In order to prevent astronauts from getting infected with diseases and to make them able to adapt to the earth's environment as soon as possible without being disturbed, they are isolated. After the quarantine of
, the three astronauts are likely to be transferred to the nursing home of the space center for medical treatment for at least one month. During this period, professional doctors will conduct comprehensive examinations of their bodies and perform some targeted medical treatments. After
, they will have to undergo at least 3 months of rehabilitation training, gradually restore physical training, and undergo phased medical examinations.They can only return to their normal life and daily training until they are evaluated and restored to their previous state of space missions.
Shenzhou No. 14 is coming soon, the search and rescue work is ready, we are waiting for them to return on the ground!
