Rebirth of science and technology academic master

Chang'e-4's engine reverse-thrust brakes, continuously reducing the descent speed. The Chang'e-4 detector slowly descends. Under the lift of the reverse-thrust rocket engine, it gradually descends to an altitude of 100 meters. After hovering for a while, it begins to take shelter. In the obstacle stage, there are only 30 meters left.

Then it fell into the moon in a very graceful manner, and this scene was transmitted back to the earth's ground command center 380,000 kilometers away through a relay star, and then broadcast live worldwide, and was seen by everyone who paid attention.

With more than 100 million people watching the live broadcast, the lander's solar panels were unfolded, the lander's transfer mechanism was unlocked and unfolded, the rover's solar panels and mast were unfolded, the rover moved to the lander's transfer mechanism, and the lander's transfer mechanism was unlocked and descended. , the patrol vehicle was transferred from the lander to the lunar surface, and after completing mutual photography between the two vehicles, they started their detection work respectively.

At this moment, countless people cheered excitedly, and countless descendants of Yan and Huang burst into tears with excitement at this moment. Even if they did not usually say some abnormal words and look down on their birthplace, at this moment, a kind of coming from The touching feeling deep in the soul touches the heart.

On the CCTV live broadcast channel, the invited guests clapped and cheered excitedly, spreading the meaning of this moment of the Chang'e-4 detector to people!

"Viewers, the landing site of the Chang'e-4 probe is located in the Von Karman crater in the South Pole on the far side of the moon. The Von Karman crater is a huge ancient impact crater with a diameter of about 180 kilometers and was formed about 4.55 billion to 3.92 billion years ago. It is named after the famous Hungarian-American engineer Theodor von Karman. It is worth mentioning that von Karman was Qian Lao’s mentor. When it was first formed, magma once flowed in the von Karman crater. The result is a very flat southern area. The central area of ​​the crater has a small peak that connects to the rugged terrain to the north."

"Von Karman Crater is located in the larger Aitken Basin, named after American astronaut Robert Grant Aitken. The basin is approximately 2,500 kilometers in diameter and 13 kilometers deep, from the deepest point to the highest point With a drop of about 16 kilometers, this is the largest and oldest impact crater known in the solar system. 90% of its area is distributed on the far side of the moon, with only a small part on the front side. The basin preserves the rocks of the original lunar crust and collects The data on rocks in this area can help scientists better understand the composition of the moon and is of extremely high scientific research value."

"In order to ensure the smooth landing of Chang'e 4, the landing site must be flat enough. In addition, there must be suitable lighting. The latitude of Von Karman Crater can ensure sufficient lighting without being exposed to direct sunlight. Because It is landing on the back side of the moon, and it cannot communicate directly with the earth while the lander is powering down, so it has to rely on the "Queqiao" relay satellite for signal transfer."

The invited experts introduced to everyone the place where the Chang'e-4 probe landed and the difficulty of landing. It was several times more difficult than landing the Chang'e-3 probe from the front of the moon.

Moreover, the time it took the Chang'e-4 probe to travel from the earth to the moon was much shorter than that of the Chang'e-3 probe, and the orbit was also very different. Coupled with the two relay satellites, it shows that China has made another progress in aerospace technology. The huge progress also brings a successful conclusion to the second phase of the lunar exploration project.

"Are you curious why the moon has a back side? This starts with the tidal force. When we are at the beach, we can intuitively see the rise and fall of the tide. This is due to the tidal force of the sun and the moon on the earth. .When the tide enters the trumpet-shaped terrain, the water level rises more obviously, such as the spring tide of the Qiantang River in my country."

"Since the moon is much closer than the sun, its tidal force on the earth is about twice that of the sun, so we focus on the moon's tidal force on the earth. The earth and the moon can actually be regarded as a binary star system, and the moon's non-uniform gravitational field increases The rotation of the earth around the center of mass of the system causes a "bulge" to bulge on the side of the earth close to the moon and on the side far from the moon. These two "bulges" will have a braking effect on the earth's rotation, which is why the earth rotates more and more. The reason for the slowness is that a leap second will be added in a few years. In the same way, the tidal force of the earth acts on the moon in the same way, making the moon's rotation gradually slow down, and eventually the rotation period is equal to the revolution period and no longer slows down. , this phenomenon is called "tidal locking" in astronomy."

"After the moon is tidally locked, only one side faces the earth. It is like a person looking around you in a circle. You can only see his front and not his back. Of course, because the moon has a "balance" The phenomenon of "motion", the area of ​​the moon that can be seen from the earth can reach up to 59%. This is mainly due to the fact that the moon's orbit is actually an ellipse and the rotation axis has an inclination angle with the ecliptic plane. "

Experts introduced some knowledge about the moon to everyone. The moon is the natural satellite of the earth and the closest large celestial body to the earth. Human beings have been interested in the moon very early. With the advent of the industrial age, human productivity has greatly improved, technical means and tools have also improved a lot, and the detection and understanding of the moon has far exceeded that of any other era.

But even so, in fact, humans know very little about their neighbors, even experts, let alone ordinary people.

Even in China, which has a scientific foundation, ordinary people only know that the moon is the nearest large celestial body to the earth, a natural satellite of the earth, and is related to the ebb and flow of the tide. Most of them are Chang'e flying to the moon and Wu Gang cutting down the laurel tree.

They simply don’t know that people can only see one side of the moon now, that is, the front side. As for the back side, it cannot be observed from the earth.

As for the Von Karman crater, who knows what it is.

"As early as 1959, the former Soviet Union's Lunar-3 probe photographed the far side of the moon for the first time, successfully transmitted the image back to the earth, and built the world's first lunar instrument. In 1965, the former Soviet Union's Lunar-3 probe While flying by the moon, it sent back 25 clearer photos of the far side of the moon. From the photos, you can see a chain of craters hundreds of kilometers long. According to these precious photos, the new moon It encompasses 95% of the Moon's surface."

"We all know that the Apollo 11 spacecraft completed the feat of mankind's first manned moon landing. Armstrong's famous saying "One small step for man, one giant leap for mankind" seems to be echoing in our minds. Before that, Apollo 8 in December 1968 The spacecraft entered lunar orbit for the first time and returned to Earth after completing a circumlunar flight. The three astronauts became the first humans to see the far side of the moon with the naked eye. Since then, astronauts flying to the moon have all seen it with their own eyes from above the lunar orbit. Been to the far side of the moon.”

"In 1962, NASA's "Wanderer" lunar probe was unable to work due to a computer malfunction. It eventually crashed into pieces on the back of the moon and became the first probe to land hard on the back of the moon. Of course, it did not send back any useful information. Data. From 1966 to 1967, NASA obtained a large amount of information about the far side of the moon through a series of detectors of the "Lunar Orbiter" project."

"This time the Chang'e-4 probe has achieved mankind's first soft landing and patrol survey on the far side of the moon, and has achieved relay satellite communications between the far side of the moon detector and the ground station. It is the first time in the world to achieve very low-frequency radio astronomical observations on the far side of the moon. It has entered orbit. The accuracy is the best in the world. It is also the first time in China to realize the space application of isotope nuclear batteries. It is also the first time in the world to carry out a reflective laser ranging test beyond the distance between the earth and the moon. It is also the first time in the world to carry out neutron and radiation dose and neutral atom distribution on the back of the moon. And research on low-frequency radio astronomy observations at the Earth-Moon L2 point!"

Experts have given high praise to the successful soft landing of the Chang'e-4 probe on the back of the moon. After all, the breakthrough made by the Chang'e-4 probe is obvious to all, and the international community has expressed its praise for the Chang'e-4 probe. The technology that comes out expresses wonder and envy.

At the ground command center, there was also warm applause. This time the Chang'e-4 probe achieved a perfect soft landing with a very graceful landing posture. This represents their great success, joy and achievement. This feeling can only be truly felt by these people who sincerely love aerospace and are willing to devote their lives to the aerospace industry.

However, at this moment, the team showed strong psychological quality and professionalism. The commander-in-chief said: "Report on the current status of the Chang'e-4 detector!"

"The engine is running normally, as originally predicted!"

"All scientific payload instruments in the detector are not damaged and can be used normally!"

"The Yutu-2 lunar rover is not damaged and can leave the module at any time to carry out detection missions!"

"The signal receiving system is normal, the signal is delayed for three seconds!"

"The thermal control system is normal, the detector temperature..."

It can be said that this mission is perfect. The Yutu-2 lunar rover, which is responsible for the survey mission on the far side of the moon, can also leave the cabin to perform tasks at any time.

The Chang'e-4 detector is the backup to the Chang'e-3 detector, but the breakthroughs and significance it has made are even greater than those of the Chang'e-3 detector.

Its success means that China has officially come to a successful conclusion in the second phase of the lunar exploration project and can enter the third phase of the lunar exploration project with the best attitude. It also represents that China has made a series of breakthroughs in aerospace technology. It also means that as the Chang'e-4 probe detects the back of the moon, China's understanding of the earth will continue to increase, and it will also lay a solid foundation for China's manned moon landing.

Qin Yuanqing looked at the busy ground command center, smiled, and left the command center silently. After all, although he had contributed some efforts, the honor and applause should belong to this team. It was they who continued to overcome difficulties and made technological breakthroughs again and again. , today has just happened, and they deserve the honor and applause they deserve.

As for him, he no longer needs these honors and applause. He already has enough of them. Having these is not even the icing on the cake. Without these, it doesn't hurt.