Lead
"Protective shield" refers to the "shield" used when the spacecraft returns to the earth, and when the spacecraft returns to the earth, it usually experiences a "high-temperature" environment, why is it said to be "high-temperature"?
The reason is that in the process of spacecraft return, the spacecraft not only has to "break the sky", but also encounter the "atmosphere", when the spacecraft collides with the atmosphere, because the speed of the spacecraft is still relatively fast, so the friction generated at this time is very large, coupled with the close range of solar radiation, so the spacecraft will be affected by high heat.
So, in such an extreme situation, how can the spacecraft guarantee the safe return of the people and cargo it carries?
In fact, this depends on how the "fire cover" is designed, different thermal protection systems can protect the spacecraft to different degrees, it can be said that only the real "return in the flames" spacecraft technology level is really qualified, so the research of this "protective cover" is also very critical.
The protective shield has also been constantly updated and iterated, and the emerging technology that has attracted more attention is the "inflatable reentry deceleration system", which has also been applied by research teams in China and the United States, and is being tested intensively.
What is it that makes this new technology so popular?
What are its advantages?
How has it been applied by research teams in China and the United States?
First, the research of protective cover and thermal protection system.
When the spacecraft returns to Earth, it will cause a large amount of air to move when it hits the atmosphere, so the density of the air will be a so-called "shock wave" in space.
In fact, it is also because the spacecraft is just about to pass through the atmosphere at a very fast speed, so the speed of the spacecraft is still relatively fast at this time, so it will encounter too late to retreat, that is, it will encounter the atmosphere.
Because above the atmosphere, the speed of the spacecraft can also reach 8 kilometers per second, or even faster, but there is only an extremely low density above the atmosphere, and the gradually decreasing density will not have much effect on things from space, but it will have a great impact on things from the atmosphere.
As a result, there is only very sparse air above the atmosphere, however, at about 100 kilometers above the surface, the density of the atmosphere increases dramatically, and the density of the atmosphere increases dramatically as the distance from the surface decreases.
And when the spacecraft flies into the atmosphere at a speed of 8 kilometers per second, when it hits the atmosphere, because the speed of the spacecraft is very fast, even in the atmosphere of the rarefied layer of the atmosphere, a large amount of air flow can be generated, following the spacecraft, as the speed gradually decreases, the density gradually increases, resulting in a larger and larger difference, and the resulting shock wave is the so-called "shock wave".
Moreover, when the spacecraft enters the "shock wave", it is equivalent to entering a very high-speed "air flow" environment, and in this environment, the spacecraft with a speed of 8 kilometers per second will produce a large flow resistance.
When the spacecraft touches the atmosphere, the personnel and cargo carried by it will also be affected by the air flow, so at this time, the astronauts cannot return to the surface immediately, but must wait until the "shock wave" weakens before descending the speed, so as to ensure the safety of the astronauts.
Moreover, in fact, "shock wave" and "thermosphere" are two different concepts, and "thermosphere" refers to the top of the "shock wave", and in this area, due to the friction between the surface of the spacecraft and the atmosphere, a large amount of heat will be generated, and from the spacecraft touching the atmosphere, to passing through the "shock wave", personnel and cargo can return to the earth, perform the landing mission, this time period is only about 3 minutes.
And because the speed of the spacecraft return is still relatively fast, so when returning to the ground, the appearance of the spacecraft still retains a "thermosphere", therefore, when the spacecraft descends in the atmosphere, it will also encounter atmospheric friction and solar radiation, so the outside temperature is not only very hot, even hotter than the sun, which is like the spacecraft is going to disappear in flames, so at this time, personnel and cargo need to have a "protective cover" to avoid excessive exposure to high temperatures.
Nowadays, all kinds of spacecraft are very heat-resistant, but in the face of such a high temperature environment, there is still a need for a "protective cover" to protect, which is also the most important role of the protective cover, and the emergence of the protective cover has also greatly promoted the pace of human exploration of the universe.
Nowadays, space exploration is also becoming more and more diverse, and as a result, different types of shields are required to protect them, which in turn are divided into different thermal protection systems.
So, why did China and the United States cooperate in the thermal protection system, and how is the thermal protection system divided after the cooperation?
Through the exploration of the atmosphere by spacecraft, it is found that the situation of the atmosphere is very complex, including "shock wave heat protection", "heat sink heat protection", "burn ant heat protection", "reusable thermal protection system" and so on, and these protection systems are all functions of "protective cover".
2. Inflatable re-entry deceleration system.
With the use of more spacecraft and the continuous development of manned space missions, the scale of spacecraft has gradually increased, so the technology that is now at the forefront of research is the "inflatable reentry deceleration system".
Before studying the "inflatable reentry deceleration system", it should be clear that "reentry" refers to space exploration again after the spacecraft has completed a space trip and successfully returned, and this process is called "reentry", and the process of "reentry" is also very complicated, mainly because the speed of the spacecraft is too fast.
It may not only lead to the "thermosphere" phenomenon in the process of returning to the spacecraft, but also may cause "thermal separation", so in order to avoid this series of safety hazards, a "re-entry deceleration system" is needed to ensure it.
The "inflatable re-entry deceleration system" is optimized from the conventional "re-entry deceleration system", which is mainly composed of two parts: an inflatable thermal shield and an inflatable parachute system.
Compared with the conventional "re-entry deceleration system", the advantages of the "inflatable re-entry deceleration system" are as follows: first, it is lightweight, much lighter than the conventional system; second, it can maximize the deceleration performance; Third, it has the characteristics of large resistance area, free and flexible operation, etc., for deep space exploration tasks, the use of inflatable reentry deceleration system can better protect the safe return of goods and personnel.
Therefore, the "inflatable reentry deceleration system" has become an emerging technology that has attracted much attention, and this technology is widely involved in various fields, but at present, it is still in the development stage.
The United States has been at the forefront of the world in the research technology of the "inflatable reentry deceleration system", and has been researching this technology for more than half a century.
The United States has also developed two different inflatable reentry deceleration systems, namely the stacked ring type and the double-layer conical inflatable bag type, and the U.S. research team also plans to carry out some important space missions in the "2020s", so as to move towards the practical application of the "inflatable reentry deceleration system".
At the same time, China is not willing to be left behind in research, China has also invested a lot of manpower and material resources in research, as an emerging technology of inflatable reentry deceleration system, domestic research results have also attracted a lot of attention.
In terms of the research of this technology, China has carried out the research of two different types of inflatable reentry deceleration systems, namely the single inflatable ring membrane type and the double-layer conical inflatable bag type, and in this research, China has also shown its technical strength and made a huge breakthrough in technology.
3. Cooperation between Chinese and U.S. research teams.
China and the United States have always kept pace in the field of space technology, and they have learned from each other, learned from each other, and cooperated with each other, which has also become a beautiful landscape in this field.
Nowadays, China and the United States have begun to have more intersections in the research direction of "inflatable reentry deceleration system", and their respective research teams have also begun to carry out technical exchanges and cooperation to jointly promote the development of this emerging technology.
As an emerging technology, the "inflatable reentry deceleration system" will provide more possibilities for the emergency return of astronauts and deep space exploration, and it has many advantages such as light weight, large resistance area and convenient transportation, so it has also attracted everyone's attention.
Today, the research teams of China and the United States have excellent research technology in the field of "inflatable reentry deceleration system", and the cooperation will better promote the development of this technology.
epilogue
The return of spacecraft to Earth at high temperatures is a technical challenge, and the research of protective shields and thermal protection systems is also a crucial part of undertaking this technical challenge, which also reflects the courage and wisdom of human space exploration.