The Chinese astronauts successfully completed their mission, and it was time to return to Earth
The return capsule was surprisingly black on one side and white on the other.
The surprising contrast makes people wonder if there is a safety hazard.
What's going on with the half-black, half-white return capsule? Is there a safety incident?
There are real sources of information in this article, which are repeated at the end of the article
The appearance of the return capsule has caused controversy
On October 31, 2023, the Shenzhou-16 mission was successfully completed and returned to Earth and successfully landed at the Dongfeng landing site, which also marked the successful completion of the first manned mission after the Chinese space station entered the application and development stage.
After 154 days of space flight, the three heroes have completed their mission and are undergoing months of physical rehabilitation in Beijing, after all, the microgravity environment of space is a burden on the body.
And it was at this exciting moment when the astronauts returned that some netizens keenly discovered some key points, such as the black appearance of the return capsule of the manned spacecraft of Shenzhou 16, and they felt that there must be some problems with this return capsule.
Moreover, one side is black and the other side is relatively clean, and the burn is not evenly and clean, is there a safety accident? Don't worry, we can find that this phenomenon has been the case in the return capsule of the past generations.
It was also pointed out that the Indian return capsule was clean and showed no signs of burning, but what was going on?
The problem is also in the atmosphere
We know that the earth has a thick atmosphere, and this atmosphere can be said to be loved and hated, and whether the launch vehicle flies out of the earth or back to the earth, it has to go through the process of breaking through the atmosphere.
Let's look at the return capsule again, in fact, the return capsule is designed to be unevenly ablated, and the return of the space return capsule is not an easy thing.
This is where the atmosphere comes in, and the atmosphere rubs against the re-entry capsule, which has a braking-like effect due to friction in the process.
On the one hand, the atmosphere is needed to rub and slow down the speed of the return capsule, on the other hand, it is necessary to brake appropriately, if the brake is too much, it is not difficult to understand, let's take an example.
The driver sits in the car, driving in the highway, a sudden braking, if there is no seat belt, it is likely that the driver will fly directly out of the windshield, the space return capsule is the same reason, the gravitational acceleration that human beings can continue to withstand is generally about 9 G.
The body of an astronaut who has experienced an atmospheric deceleration will not be able to stand it, which is a physiological limit that no amount of training can make up for, and it is very important to grasp this degree, let's take a look at the overall return process.
After the Shenzhou-16 spacecraft rotated around the earth five times, it was about 390 kilometers above the ground, and then it had to make two attitude adjustments, and also carry out orbital return separation and push-back separation.
When the spacecraft is only 120 kilometers away from the ground, the return capsule of Shenzhou-16 begins to enter the atmosphere, and the last 120 kilometers are the most difficult part of the Shenzhou spacecraft's return to Earth.
After adjusting the attitude of the return capsule, it will rush into the atmosphere at a speed of 7.9 kilometers per second, because the speed is super fast, the friction between the return capsule and the atmosphere is intense, and the friction will produce combustion, and re-enter the atmosphere.
The key point of the problem lies in the process of friction combustion, friction heating will produce ultra-high temperatures, for the safety of astronauts, it is certainly unrealistic to resist this high temperature, at this time, it is necessary to work the appearance of the cabin.
In the face of the high temperature generated by friction, the coating on the surface will quickly sublimate because of the heat absorption, and there will be no high safety hazards if the heat is taken away.
It's also easy to understand that when our body is hot, spraying alcohol on the skin, as the volatile heat of the alcohol will also be taken away, which is the same reason, and the color of these heat-resistant coatings after being ablated is the dark color we see.
One of the more black technology is that in the porthole part of the cabin, the coating is specially designed to maintain self-cleaning, so that it is convenient for astronauts to observe the external situation at any time and observe re-entry into the atmosphere in the cabin, which is the treatment that astronauts can enjoy.
Special design for the appearance
The shape of the space return capsule is also not symmetrical, and in the process of orbiting the earth, it will be adjusted by attitude and replaced with a special attitude, on the one hand, to prevent individual parts from being burned by high temperature for a long time, and on the other hand, to slow down the speed.
When entering the atmosphere, the attitude as a whole forms an angle with the atmosphere, and the bottom of the return capsule with the thickest heat-proof coating will not face the atmosphere, otherwise it will be dangerous because of too much resistance, and it will be slightly biased towards the earth into a peculiar posture.
As for the return capsule half of the normal color, it is because the heat-proof outsole is installed at the bottom, and after the most serious friction, it is time to reverse the propulsion deceleration and open the parachute, and the heat-proof outsole will be thrown away in this process.
According to the experience of astronauts, the temperature inside the re-entry capsule is comfortable, and sometimes the right thing is counterintuitive.
Why is the Indian spacecraft return capsule clean
India launched an online propaganda offensive after the landing of Chandrayaan-3, and the technology of Chandrayaan-3 is cheap and easy to use, and peers want to buy their technology, which is not to blame India's arrogance, it can only be said that it is all set off by peers.
India's Chandrayaan-3 is cheap, it is really cheap, whether it is good or not, to put it bluntly, India's return capsule was brought up when the manned rocket was launched, and finally successfully landed in the sea and was recovered.
This time in the propaganda of the Indians themselves it was quite successful, but what is the actual situation?
The Indian capsule was separated at an altitude of 17 kilometers above the ground, that is, it landed at an altitude of only 17 kilometers.
Such a low distance is naturally impossible to be rubbed by the atmosphere, and there will be no traces, which is how it looks clean.
End
Those who say that the appearance of the Shenzhou return capsule is black and compare it with India, or don't say goodbye, these two are not the same grade at all, how can they compare?
What is more interesting is that after returning to the ground, the return capsule will not be put into use again because of the inevitable damage to the components, in addition to normal scientific research, it can also be placed in the museum for people to visit, after all, the return capsule is a rare thing, with important scientific research and historical significance.
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Fang Zhou,Liang Xin,Deng Huoying,Dong Yanzhi,Dai Xiaowei. Performance of honeycomb-enhanced low-density silicon-based ablative heat-resistant materials [J]. Aerospace Materials and Technology,2021,51(05):79-83.
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