Lead
In November 2023, after 28 days of exploration, Chang'e-6 "Yutu" finally completed all the work on the moon and ushered in the moment of returning to Earth.
After about 50 hours of acceleration from the moon out of the gravitational zone, Chang'e-6's return orbit has been determined, which means that Chang'e-6 is returning to Earth.
And the difference between this return trip and launch is that the launch has to fly up, and the return trip has to go down, so what are the headaches in the return process?
That's right, it's a matter of landing.
Black Barrier Zone: Two horizontal shuttles.
The return trajectory of Chang'e-6 adopts a semi-ballistic jump-off method, which makes Chang'e-6 seem to have taken a "lift-off" elevator when it enters the earth's atmosphere, and the speed of high-speed downward has been effectively slowed down.
However, this "slowdown" is not a buffer for the whole process, only in the first half of entering the earth's atmosphere, when returning to the second half of the earth's atmosphere, Chang'e-6 is still falling at a very high speed.
In this process, Chang'e-6 will go through two black barriers, which are about 20 minutes apart, and Chang'e-6 will collect all the data from the lunar surface and return to Earth to the end of the landing work, a total of 30 minutes.
It seems like plenty of time, but it's hard to imagine that it only takes 30 minutes to hit the ground.
In an instant, it descended from a low-speed flight on the surface of the moon to a high-speed flight in the Earth's atmosphere, and then from a high-speed flight in the atmosphere to the Earth's surface.
In this process, the most difficult thing for Chang'e-6 was when it was burned into a red light district by the atmosphere.
By the time Chang'e-6 entered the atmosphere, the speed had almost dropped, but there was still a lot of airspeed, so the outer layers of Chang'e-6 were parachutes to reduce speed and drag.
However, once it enters the atmosphere, the density becomes very large, the friction force becomes greater, and the process of friction will also cause the detector to produce a high temperature.
Before the parachute of the Chang'e-6 returner is deployed, the probe will be burned into a red light zone by the temperature generated by atmospheric friction.
This red light area, also known as the black barrier area, has two main functions, the first is to shield the signal of Chang'e-6, because the signal emitted by Chang'e-6 will be burned, so the ground cannot receive the signal of Chang'e-6.
The second is the loss of contact with the ground command center, at which time Chang'e-6 is in full control of itself and decides how to land, and it is impossible for the ground to command Chang'e-6 in real time.
Although there is a part of the autonomous landing capability, however, this is only the most basic, many other autonomous landings are dependent on the command of the ground, but this time it cannot be used, in this case, Chang'e-6 can only rely on itself.
The Chang'e-6 system is like a person living in the dark who suddenly sees the light and is excited, but it also needs to stay calm and grasp the direction of progress by relying on its own ability.
The Chang'e-6 probe and returner are not separated, so it shoulders the two roles of probe and returner.
After the black obstacle area slides down, it will shoulder the burden of the detector, detect the environment in which it is located, and adjust its speed and attitude to obtain an optimal landing posture.
This work is a great test for Chang'e-6 of its autonomous landing ability, but Chang'e-6 is a Chinese astronaut, and it will use its own ability to complete the mission very well, just like Chinese astronauts.
Twenty-four minutes later, Chang'e-6 re-entered the black barrier area, this time for a relatively short period of 10 minutes, but it was the most dangerous time.
After passing this black barrier area, Chang'e-6 will land, and the completion process will be relatively easy, because it has adjusted itself to the best landing state by its own ability, and when it is close to the ground, the parachute is deployed, and it slowly lands on the ground to complete the task.
Chang'e-6 "hit the water".
The landing process of Chang'e-6 can be said to be orderly, but the astronauts have done many experiments before in the hope that it will be perfectly completed in the first mission.
The 30-minute landing time allowed Chang'e-6 to land within this time, but this work was difficult, so the astronauts conducted experiments.
In 2014, the mainland implemented the Chang'e-3 vehicle from the moon back to Earth, and in order to allow Chang'e-3 to complete the landing method from parachute opening to full landing in 30 minutes, Chang'e-3 conducted experiments a year in advance.
In the Chang'e-4 mission, the Chang'e-3 experiment was further improved, but the Chang'e-5 also carried out the same experiment.
These experiments have accumulated experience and refined lessons again and again, and finally introduced the landing method of Chang'e-6, which is also the most secure landing method.
The 30-minute landing time is very tight, but it is based on the experience and lessons learned before, as well as the optimal landing time that has been experimented with since then.
In these 30 minutes, Chang'e-6 still has to go through the black barrier area twice, although Chang'e-6's system will automatically record its status through the black barrier area, but when it is connected to the ground command, it still has to wait until half an hour later.
In the 30 minutes between this time, Chang'e-6 has actually landed on the ground, but the ground does not know the status of Chang'e-6, so these 30 minutes are also the most anxious.
After passing through the black barrier area twice, the Chang'e-6 returner began preparations for landing in Hubei, and in order to be able to complete this work in such a short time, Chang'e-6 adopted the method of drifting.
Playing water drifting allows the object to jump on the surface of the water or underwater, so the surface or underwater has a great resistance to the speed of the object, so that the speed of the object can be reduced a lot in an instant.
Chang'e-6 uses such a jumper to return to the water, but Chang'e-6 has to land on the mainland after returning to Earth, which needs to create another resistance in the air where there is resistance in order to land Chang'e-6.
During the flight, Chang'e-6 first passed through several layers of the atmosphere, and there are a large number of oxygen molecules in the atmosphere, which is a very easy environment to collide.
This collision-prone environment is inseparable from other environments in the air and does not increase the airspeed of Chang'e-6, so it is very suitable for Chang'e-6 to land, and Chang'e-6's system is also based on this principle.
Chang'e-6 experienced a black barrier in the air and still did not enter the 300-kilometer range, at this time, Chang'e-6's system was still not activated and could not make an active landing.
However, the path traveled by Chang'e-6 is often constantly descending, and combined with the extreme speed of flight, all this is preparing for the landing of Chang'e-6.
The Chang'e-6 system was officially launched after the second black barrier area experienced in the air, at this time, Chang'e-6 was already ready, and with the start of the system, Chang'e-6 landed quickly, and after 30 minutes, it successfully landed in Inner Mongolia.
The key to space exploration: the backhaul.
Space probes probe in space, play the role of eyes, see some unprecedented landscapes of human beings, and bring back unprecedented knowledge, which is the importance of space exploration.
But this is only one part of space exploration, it also has an equally important mission, which is to return to Earth with human knowledge and expectations and show mankind everything it sees in space.
However, the return journey is the most difficult and complicated, because it not only has to complete the process of returning from the moon to Earth, but also in the process, it also has to complete the transfer of data collected from the moon.
Therefore, for space probes, the way back is equally important, which is why the return work is more difficult than the launch work.
In the case of attaching more importance to the return trip, we have also made great efforts in this regard, and the return trip refers to the process of the probe returning to the earth, and this work is on the return capsule of the probe.
From liftoff to descent, they are inseparable from the return capsule, and they are composed of two parts: the orbiter and the return capsule.
The main function of the orbiter is to provide energy and support flight, while the return capsule is mainly responsible for return and landing, so it must have more tasks than the former, including receiving rich data from the orbiter.
There are three compartments in the return module: the command module, the return module and the service module, the command module is mainly responsible for communication and control, the return module is responsible for the isolation and landing system of the return vehicle, and the service module mainly has the electronic equipment of Chang'e-6.
The Chang'e-6 mission is more complex than previous missions because it has to transfer the material it brings back to the surface, which means its systems are more complete.
This is a big step forward for the mainland, which shows that our technology has made another big step forward and is also among the best in the world, and it fully shows that we have made more development in this regard.
Chang'e-6's return journey took several months of exploration, and unlike previous missions, it contained a large amount of material, which also complicated its systems.
It can be said that it is easy and pleasant to explore the moon, but at the end of the return trip, there will be great sequelae, and it will usher in a major test, that is, the separation of the return capsule and the orbiter and the return of the return capsule.
epilogue
The task of Chang'e-6 is not only arduous and high-risk, but our ability to complete the mission so firmly fully reflects our good national strength and technology.
Being able to accomplish the task in the midst of so many risks shows not only our national strength and technology, but also our courage and confidence.