Key Sources:
CCTV News "Welcome Home! Watch Augmented Reality Technology "Disassemble" the Full Steps of the Return of God Seventeen" 2024.4.30
Global Network "Attitude Adjustment, Braking, Crossing Black Obstacles, Parachute Descent...... What is the whole process of returning to Shenzhou 12?》2021.9.17
Preface
The Shenzhou-17 spacecraft, carrying a crew of astronauts, has successfully evacuated China's space station and embarked on its way home.
And this time, the Shenzhou-17 manned spacecraft will adopt a 5-lap (7.5 hours) fast return scheme, which is 19.5 hours shorter than Shenzhou-12!
How exactly is this done?
God XVII returns
At about 8:43 a.m. today (April 30), the Shenzhou-17 spacecraft has been carrying Tang Hongbo, Tang Shengjie, and Jiang Xinlin, and the three astronauts have been successfully evacuated from the Chinese space station.
This also means that the Shenzhou-17 crew and the Shenzhou-18 crew have successfully completed the on-orbit handover, and the mainland's Shenzhou-17 mission has come to an end.
Next is the thrilling return stage, the Shenzhou 17 crew will return to Earth from space 400 kilometers above the ground, and the speed of descent has reached 28,000 kilometers per hour.
But this is different from the past, this time Shenzhou 17 adopted a completely different return method than before, the previous Shenzhou 12 returned, it took nearly 28.5 hours to successfully return to the earth, so the process can be said to be "very painful".
After all, deep in space, attention must be highly concentrated, and when performing the return mission, not only can not sleep, but also observe the status of the spacecraft and various data indicators at any time.
The slightest carelessness may cause the failure of the return plan, which will lead to a serious threat to the life of the astronauts, so the long-term return plan seems to be "safe" in terms of time.
However, for astronauts, in the face of psychological pressure and physical pressure, it is conceivable that the body will also be in an extremely tense state, and the astronauts will stay in the return capsule for a long time in this process, so it will be a huge test for the astronauts' endurance and psychology.
This time, Shenzhou 17 adopted a completely different approach, shortening nearly 20 hours compared to the 28.5 hours with Shenzhou 12, so that the astronauts do not have to introduce such a long return process.
Because this time Shenzhou 17 only needs to circle the earth 5 times (seven and a half hours), while the previous Shenzhou 12 needs to circle the earth 18 times (about 27 hours).
Shenzhou-17 will be able to return to Earth after four stages: braking deorbit, free gliding, re-entering the atmosphere, and parachute landing, and the entire process of returning to land will take about 50 minutes.
Then, according to this rapid return technology, Shenzhou 17 will arrive at the mainland's Dongfeng landing site at about five o'clock in the afternoon today (April 30).
In addition, five helicopters of the mainland's Shenzhou-17 search and rescue recovery air detachment have reached the assembly point.
Then, it can be seen that compared with the previous return plan of Shenzhou 12, this time the return plan of Shenzhou 17 has been reduced to one-third of the original.
So, how good is this fast return technology?
Key Sources:
Global Network "Attitude Adjustment, Braking, Crossing Black Obstacles, Parachute Descent...... What is the whole process of returning to Shenzhou 12?》2021.9.17
Global Network "Attitude Adjustment, Braking, Crossing Black Obstacles, Parachute Descent...... What is the whole process of returning to Shenzhou 12?》2021.9.17
Fast return technology
The reason why such a scheme can be used is that China's aerospace industry is more advanced in technology and solutions, because returning from space to Earth requires a very strict "window period".
Because it is necessary to ensure that Shenzhou-17 is ready to land in the predetermined area of the Dongfeng landing field, the window period is very important, Shenzhou-17 rotates rapidly in the earth's orbit, and the orbit tilt angle is 41.5 degrees.
In other words, Shenzhou 17 only needs one and a half hours to orbit the earth, and during this period, the earth has been in a state of high-speed rotation.
Therefore, it is very important to choose a certain time to let the spacecraft deorbit and enter the atmosphere, and choose the predetermined angle, so that after entering the atmosphere, the return capsule will also land in the predetermined area.
Therefore, the reason why Shenzhou 12 spent nearly 30 hours was that it had been waiting for an opportunity, and there were very few perfect opportunities, and it also took time for the return capsule to adjust in orbit, so it took a lot of time.
This time, the reason why Shenzhou 17 adopted the fast return method is that the most critical point is to reduce the number of circles around the earth of Shenzhou 17, thus helping the return time of Shenzhou 17 to be greatly reduced.
The reason why Shenzhou-17 can achieve such a bottom is because the technology on Shenzhou-17 is more mature than the previous 12, and it also represents that China's aerospace has a higher degree of mastery of the earth's orbit!
First of all, Shenzhou-17 needs to get out of the Chinese space station first, fly into the earth's orbit, and then circle the earth 5 times, and constantly adjust the attitude of the spacecraft, which is officially because Shenzhou-17 has made new progress in thrust reverser rocket braking technology.
Then, through the equipment on the spacecraft, the angle is adjusted again, and after the timing is right, the landing target has been determined, and the spacecraft can enter the atmosphere.
This is because of the results of China's exploration of the spacecraft return mission, and by using the ignition braking of the Shenzhou spacecraft, the return time may be further shortened in the future.
Although the time has been shortened, the level of danger of entering the atmosphere is still high.
So, what are the dangers that the re-entry capsule encounters after entering the atmosphere?
Key Sources:
CCTV News "Welcome Home! Watch Augmented Reality Technology "Disassemble" the Full Steps of the Return of God Seventeen" 2024.4.30
CCTV News "Welcome Home! Watch Augmented Reality Technology "Disassemble" the Full Steps of the Return of God Seventeen" 2024.4.30
Dangers that may be encountered
After Shenzhou 17 undergoes the ignition and braking of the spacecraft and enters the predetermined orbit, it is necessary to choose a good angle to break through the earth's atmosphere, which is also one of the most dangerous parts of the return journey.
The first is in the "return speed", because the spacecraft itself has reached the "first cosmic speed" in orbit, which is far beyond people's imagination, about 7.9 kilometers per second!
However, the speed of the breakthrough of the atmosphere will be even more exaggerated, and it has far exceeded the first cosmic velocity, even reaching 8 to 11.7 kilometers per second, so that it can successfully break through the atmosphere and reach the predetermined goal.
Therefore, the material requirements for the Shenzhou-17 return capsule are very high, because the return capsule at this time is like a meteorite smashing into the earth, so if the material is not strong enough, it may be like a "meteorite", before it has fallen to the surface, it will "disappear".
When breaking through the atmosphere, the surface temperature of the return capsule can reach more than 2000 degrees Celsius, just imagine the high temperature of 2000 degrees, Sun Wukong is estimated to be unable to eat it.
Therefore, there is a need for aviation-grade materials with high strength, wear resistance and high temperature resistance, and the aviation insulation materials used by Continental are very advanced, a new alloy material and a lightweight carbon-based micro-ablation material.
The thermal insulation material independently developed by the mainland has a characteristic, that is, the higher the surface temperature, the darker the material will be, and the darker it means that the material has stronger heat absorption ability and the temperature in the return capsule will be lower.
Therefore, when Shenzhou-17 breaks through the atmosphere, it will be like a popular gas flame, and the surface will also leave traces of carbonization.
After that, it will enter the "black barrier state", at which time all ground-controlled communications will be disconnected from the return capsule, which is also known as the "black five minutes" when the astronauts return to Earth.
The re-entry capsule will completely lose communication on the ground, and the astronauts will have to face this dangerous situation alone, and in this case, because of the ultra-high speed, even the astronauts' physical fitness will be greatly tested.
After that, it needs to be opened, and the brakes need to be applied by the spacecraft to further reduce the speed of the spacecraft, because only then will there be a chance to open the parachute and land.
In this process, Shenzhou 17 has to fly to the earth at a speed of 28,000 kilometers per hour in space, and it has to brake at the right time, open the parachute, and the speed when it is lowered to the ground is basically 0.
And this process is difficult for ordinary people to bear, not only to bear the challenge of several G's overload physically, but also to enter the state of black barrier and lose communication with ground control, so the pressure will also be extremely great
However, our astronauts are selected through layers of selection, and have a very high self-control and psychological quality, and in the physical and psychological aspects of astronauts, years of training can make them unwavering in challenges.
Then, through this rapid return trip, it can also be seen that the mainland has made great progress in the field of aerospace.
So, where is the current progress of the mainland's aerospace?
Key Sources:
The People's Government of the People's Republic of China, "A Major Breakthrough in the Tracking and Measurement of the Black Barrier Area of the Mainland Manned Spacecraft", June 4, 2023
The People's Government of the People's Republic of China, "A Major Breakthrough in the Tracking and Measurement of the Black Barrier Area of the Mainland Manned Spacecraft", June 4, 2023
China's space program
With the launch of Shenzhou-18 and the return of Shenzhou-17, the mainland has started a new journey in the fourth phase of the lunar exploration project, and some time ago, the mainland's very advanced "Queqiao-2 relay satellite" was also successfully launched.
The mainland's Chang'e-6 will also be launched in early May this year, probably during the May Day holiday, and the mainland's Shenzhou series of manned space projects have already launched the 18th spacecraft.
The mainland's manned lunar exploration project is also steadily advancing, and our new-generation spacecraft "Mengzhou" and "Lanyue" are also being developed in an orderly manner.
China's space program has always been like this, steady and steady, steadily moving forward, and there are few delays, and the launch plan will be carried out in this way every year.
On November 30, 2022, six astronauts from the two crews of Shenzhou 14 and Shenzhou 15 gave a thumbs up and shouted in unison:
"China's space station is always worth looking forward to!"
It proves that the mainland also has its own space station, and it is completely independent and independent to develop a space station!
On July 12, 2023, Zhang Hailian, deputy chief engineer of the China Manned Space Engineering Office, said that China plans to achieve a manned landing on the moon by 2030.
The name of the new generation of landers for landing on the moon is the previous "Lanyue", and the vehicle of the mainland's manned landing on the moon is the "Dream Boat".
At present, the mainland's lunar landing program has been implemented in an orderly manner, among which after the manned landing on the moon in 2030, the mainland aerospace will build a lunar scientific research test station to carry out systematic and continuous lunar exploration and related technical test verification.
And will bring more samples back to the earth, at present, a new generation of spacecraft, rockets, and manned lunar rovers are under development, and the manned lunar landing program in 2030 will be realized!
Information sources:
People's Daily Online, "Solid Progress in the Construction of a Space Power", 2024.4.24
People's Daily Online, "Solid Progress in the Construction of a Space Power", 2024.4.24
epilogue
Thus, a new generation of rapid return technology has been successful, and the continent is becoming more and more powerful in the field of space technology.
Finally, let us welcome the safe and triumphant return of the three Shenzhou-17 astronauts, Tang Hongbo, Tang Shengjie and Jiang Xinlin!
Resources:
People's Daily Online, "Solid Progress in the Construction of a Space Power", 2024.4.24
CCTV News "Welcome Home! Watch Augmented Reality Technology "Disassemble" the Full Steps of the Return of God Seventeen" 2024.4.30
The People's Government of the People's Republic of China, "A Major Breakthrough in the Tracking and Measurement of the Black Barrier Area of the Mainland Manned Spacecraft", June 4, 2023