The Shenzhou-17 astronauts have returned to Earth, returned to the Dongfeng landing site, landed successfully, and went home!
This also means that the entire mission of Shenzhou 17 astronauts Tang Hongbo, Tang Shengjie, and Jiang Xinlin has ended.
Of course, the end of this wave of missions actually means that the mainland may have "two more astronaut commanders", and Tang Shengjie and Jiang Xinlin may also take new people to carry out missions in the future.
But the time node is relatively long, so it will not be explained here.
And there is one main thing to discuss here, that is, many people think that the miracle is strange, that is, when the Shenzhou 17 astronauts returned, it was clear that China had a "Beidou precision" positioning system, so why did they rely on manual search for astronauts?
What exactly is going on, let's take a closer look at the return process.
What did the Shenzhou-17 astronauts experience when they returned?
That's right, although China's space technology is very good, on the way back for astronauts, this is a process that all countries that carry out manned spacecraft missions must go through, so what exactly has it gone through? How long does it take to go home?
This time, the Shenzhou-17 astronauts still adopted the "fast return" mode, using a 5-lap fast return scheme, and going through the stages of braking deorbit, free coasting, re-entering the atmosphere, and parachute landing.
The first step, the deceleration of the braking phase, this step is very critical, if the braking is not normal, the return capsule will not be able to enter the atmosphere, and the speed will not be reduced, so when the spacecraft is orbiting, the attitude will be adjusted. The first deceleration ended, and the return and propulsion compartments descended freely.
Later, at a distance of 145 kilometers from Earth, the propulsion module separated from the return module, the propulsion module burned out, and the return module continued to descend with the astronauts to a perigee of 100 kilometers.
The second step is to continue to decelerate, this time the deceleration is known as "re-entry".
Under the violent friction between the re-entry capsule and the atmosphere, the temperature outside the capsule reached thousands of degrees Celsius, and it was at this stage that the astronauts could see the sparks flying outside through the portholes.
You can imagine that the astronauts see themselves "completely surrounded by fireballs", and the sense of this picture is really too strong, and the pressure is really too great.
Therefore, the mainland's requirements for the psychological quality of astronauts are also extremely high. Moreover, this step is also the most critical step in the mainland's research on materials, resisting the high temperature friction of thousands of degrees Celsius, which is not something that ordinary countries can do, and it is also one of the key points that hinder many countries from carrying out space missions.
If anyone has understood, they should know that the United States is on the way back to the moon, the "Orion" spacecraft is in the first test, and the unmanned "Orion" spacecraft is in the process of returning to the atmosphere, the thermal insulation material has been unexpectedly eroded, and the result is that this problem has not been solved.
In the second step, it is also necessary to maneuver the spacecraft, adjust the attitude and other problems, and enter the black barrier area, which is very dangerous, and cannot communicate with the ground, until the spacecraft has about 10 kilometers left, and the parachute appears, which is the third step.
The third step is to open the "parachute" of the spacecraft's return capsule, first open two tandem guide parachutes, and pull out a deceleration parachute from the guide parachute, which first reduces the speed of the re-entry capsule from 200 meters per second to 90 meters per second. Later, when it was about 8 kilometers above the ground, the parachute separated from the re-entry capsule, and the main parachute began to take up its post, reducing the speed of the re-entry capsule from 90 meters per second to 8 meters per second.
At a distance of 6 kilometers from the ground, the heat-proof outsole of the re-entry capsule will be thrown away, and 4 thrust reverser engines will officially "appear". When the return capsule is about 1 meter above the ground, the thrust reverser engine ignites.
By giving the re-entry capsule an upward force, it can achieve further deceleration, and finally complete the landing buffer at a speed of 1-2 meters per second.
Therefore, this process is still more complicated, which is what the whole process goes through. I believe that seeing their families come home is also very stressful in the process.
Shenzhou 17 has "Beidou precision" positioning, why do you have to rely on manual search?
That's right, in the process of the continent's return mission, Beidou is indispensable, which is the continent's accurate positioning of the spacecraft. However, there is an important point, and that is that as mentioned above, the spacecraft has to go through a "black barrier" during the return process.
At this time, the radio communication between the ground and the spacecraft may be interfered with or interrupted, and the position can only be locked after leaving the black barrier.
What does this mean? That is, no one knows what kind of change is going on in the "black barrier area".
After it comes out, it is even more important to achieve accurate positioning, so it is very important to carry out "real-time locking" of the spacecraft by Beidou precise positioning, so Shenzhou 17 has "Beidou accurate" positioning, why do you still rely on manual search?
In fact, the ultimate point is to ensure the safety of astronauts.
In the actual search and rescue operation, directly visually confirm the position and status of the spacecraft, as well as the health status of the astronauts, which is the most critical of the entire mission.
If, in extreme conditions, the spacecraft's communication or navigation equipment fails, is there a risk?
At this time, is the manual search team extremely important?
Therefore, in fact, the root cause is stable, that is, for the sake of astronauts' "safety", to ensure the safety of astronauts in the fastest way, that is to say, "when the spacecraft lands, the searchers will arrive", now everyone understands, right?
Whether it's returning or in the middle of a mission, this comes first
That's right, in the process of the mainland's manned spacecraft carrying out missions, in fact, the mainland has always put astronauts first, at least that's what I think.
In addition to the "Beidou precise" positioning and manual search problems, there is also the situation of "launching one spacecraft and backing up one" spacecraft during the mainland's mission, which is actually to ensure the "safety of astronauts" during the entire mission.
Everyone should have also seen that when the mainland is carrying out the mission of the Shenzhou 18 manned spacecraft, there is still the Shenzhou 19 manned spacecraft on the ground on emergency rescue standby, as long as the Shenzhou 18 astronauts encounter any urgent problems, the mainland can directly launch a backup spacecraft into space, and then pick it up.
Therefore, these are all to ensure the safety of astronauts, and they are the best aspects of the mainland's aerospace strategy, which is the general situation, and once again say that the Shenzhou 17 astronauts have worked hard, and look forward to the Shenzhou 18 astronauts once again creating China's aerospace historical achievements.
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