Rebirth of science and technology academic master

On December 30, the last day of 2018, the whole country’s attention turned to the Xichang Satellite Launch Center, because today, the Chang’e-4 probe will be launched into space by the Long March 3B carrier rocket from the Xichang Satellite Launch Center.

As early as before, at the press conference, it had been explained to the outside world that the Chang'e-4 probe would softly land on the back of the moon, which would be a feat for human lunar exploration. It is also the final station of the second step of the three-step process of "circling, landing and returning" of the lunar exploration project, and serves as a link between the past and the future.

So not only China, but also other countries have set their sights on the Xichang Satellite Launch Center. The technical difficulty of soft landing a probe from the far side of the moon is much greater than that of a soft landing from the front side of the moon. It is absolutely no exaggeration to say that the difficulty has increased by two, three or three or four times.

Once China really successfully achieves the soft landing of the Chang'e-4 probe from the back of the moon, it means that China has the ability to carry people to the moon at any time.

"Academician Qin, I have to trouble you to come here!" Academician Ouyang called Qin Yuanqing.

Qin Yuanqing did not refuse and agreed: "Nothing, everyone is serving the country!"

An hour later, a special car came to pick up Qin Yuanqing. The car looked very low-key, but it was a modified vehicle. The car glass was all bulletproof glass.

Not long after, Qin Yuanqing arrived at the headquarters building of the National Space Administration, which is located on Fucheng Road, only 10 kilometers away from Shuimu University.

In Beijing, in addition to the National Space Administration, there are also the National Space Administration's Earth Observation and Data Center, Space Debris Monitoring and Application Center, and Space Remote Sensing Demonstration Center, which connect the launch center to various scientific research vessels and scientific research stations.

After arriving at the National Space Administration headquarters building, Qin Yuanqing went to the lunar exploration program ground command center after a strict inspection.

When Qin Yuanqing walked into the command center, there were already many people here, all staring at the big screen in front of them. There were at least hundreds of staff in the entire command center. They were connected to the whole world through computers and were always watching.

After all, the launch of the Chang'e-4 probe requires detailed inspections, meteorological observations, and various detection stations to detect the flight trajectory at any time for easy control.

Unlike previous probes that required several days of flight to gradually complete the Earth-moon transfer journey, this time Chang'e-4 will complete this feat after flying several times around the Earth.

In the command center, Qin Yuanqing shook hands with the main leaders, such as Wu Weiren, the current chief designer of China's lunar exploration project and an academician of the Chinese Academy of Engineering, Hao Rongwei, the chief commander of the Chang'e-4 detector system, and the chief aerospace commander!

Then Qin Yuanqing also stared at the big screen. He could clearly see all the pictures on the big screen. There are not only the Long March-3B carrier rocket standing on the launch pad, ready for use at any time, but also the Chang'e-4 detector, as well as a bunch of complex data.

"Weather No. 1, report the current situation!" Someone in the command center asked about the weather situation.

Then the latest situation was reported from the front: "Reporting to the capital, the current wind strength is thirteen knots. We have observed that fifty kilometers away, the wind strength has weakened to below seven knots. It is expected that the wind strength above the launch area will decrease in thirty-one minutes, which is in line with Launch conditions.”

"Report the situation from the measurement and control station!"

"The monitoring station reports that the rocket is normal, the fuel circulation system is normal, and the launcher is ready for attack at any time!"

As the process is filtered over and over again, the countdown begins. Everyone has raised their attention to the highest level, always paying attention to the data monitored in all aspects, and controlling the situation of all parties.

When the countdown entered five minutes to prepare, the weather conditions just entered the optimal launch conditions. At the same time, the conditions of the launch center were continuously reported to the command center in Beijing. Qin Yuanqing couldn't help but secretly admire that this aerospace project is really a high-precision project. The rigor has penetrated into everyone's bones and is meticulous. No wonder China can achieve world-famous achievements with a small amount of money.

"One minute to prepare! Countdown. 50! 40!."

When the countdown sounds "5432"

There was one second left in the countdown, and then with the sound of 1 and the accompanying command of 'ignition', the atmosphere was tense to the limit at this moment. The air seemed to solidify in this second, and suddenly exploded in the next second.

The launch tower was instantly surrounded by thick white smoke, and dazzling fireballs poured out from the bottom of the rocket and rushed into the sky. In one breath, the whole world began to tremble violently. Even across the screen and thousands of miles away, Qin Yuanqing could feel the atmosphere and powerful shock.

"Boom~~Boom~~"

Thick smoke rose hundreds of meters high, so much so that the entire Long March 3B carrier rocket was hidden. In front of this earth-shattering and shocking scene, any living thing will become extremely vulnerable.

I saw a huge rocket rising from the ground, white flames shooting out from its tail like a sword, roaring like a mountain and tsunami, soaring into the sky.

The speed of sound seems to be very fast, but in fact, for rockets, it has exceeded the speed of sound in the blink of an eye. After all, if you want an object to fly around the earth and make circular motion, the minimum initial speed must reach the first cosmic speed, and the first cosmic speed has reached 7.9km/s, which is more than 23 times the speed of sound!

The shape of the Earth-Moon transfer orbit is a cone splicing, with perigee approximately 10.8km/s and low-Earth orbit 7.8km/s. If you want to go from the earth to the moon, there is only one orbit with the smallest energy efficiency. Only by running along this orbit perfectly can you save more fuel for maintaining the orbital altitude when performing exploration work around the moon.

The more deviation, the more fuel will be used.

Qin Yuanqing had already calculated everything from the ground to the earth orbit, the earth-moon migration orbit, the moon orbit, the moon orbit to the landing trajectory, and the model also relied on this.

So soon, various monitoring stations continued to collect data and successfully entered the predetermined orbit. After the orbit around the earth was continuously accelerated, it would enter the migration orbit, and then migrate until it was about to reach the moon's orbit around the moon. It will continue to slow down until the speed reaches the predetermined orbit around the moon. After completing this step, you can proceed to orbit the moon and set on the moon!

If something goes wrong in any of these steps, it will basically fail.

As he entered the scheduled orbit around the Earth, which represented the complete success of the first phase, Qin Yuanqing did not rest, but paid attention to the flight data at all times and constantly reviewed the flight data. Others could cheer and relax, but he could not relax because This is not just the Chang'e-4 probe, but also related to China's future manned moon landing project.

Otherwise, according to the way China's detectors used to explore the moon in the past, it would take several days to orbit the earth, several days to migrate from the earth to the moon, and even longer to land on the moon.

Unknowingly, the spacecraft's speed has reached the speed requirement for the Earth-moon migration, and then it began to migrate along the originally set Earth-moon orbit.

During the migration of the earth and the moon, it first accelerates away from the earth, but when it reaches a certain position, it must slow down before the spacecraft can be captured by the moon.

After entering the Earth-Moon migration orbit, Qin Yuanqing could relax a little and go to sleep.

On this day, the spacecraft finally entered the near-lunar braking phase.

In this stage, simply speaking, the directional thrust of the engine is used to decelerate the spacecraft. Then, the spacecraft, which has decelerated to a certain value, is pushed into a lunar orbit with a perigee of 100 kilometers. After that, the spacecraft will fly around the moon in this lunar orbit.

"Track correction!" the commander-in-chief began to say in a deep voice.

"The third orbit correction is completed, the error is 0.00012 degrees!" The monitor on the side reported the data.

This error is within the error tolerance range.

With the experience of the previous three times, coupled with the deployment of monitoring stations before this launch, the use of Beidou navigation, and satellites orbiting the moon for positioning and command, the accuracy and technological content are actually far superior to Chang'e-3.

In terms of time, it also reduced four days!

Even though it’s only four days, it can actually save a lot of fuel, and you can do more things later.

"Start slowing down!"

As the command was issued, the spacecraft immediately began to use the engine to slow down. On the entire big screen, the braking process in recent months began.

The entire process was carried out rigorously according to the data and models provided by Qin Yuanqing. The minutes and seconds, the thrust of the engine, and the thrust angle were all set early and were accurate.

The speed of the Chang'e-4 probe continued to decrease. When it reached the point where it was captured by the moon, it happened to be 100 kilometers away from the moon, and it immediately began to move around the moon along this preset orbit around the moon.

This setting is actually not a circular motion, but an elliptical motion. The peri-lunar point is 100 kilometers and the far-lunar point is 400 kilometers in an orbit around the moon.

The entire ground command center burst into cheers.

Originally, Chang'e-4 was the backup detector of Chang'e-3. If all operations of Chang'e-3 were copied, the only highlight would be the landing on the back of the moon. But this time, it adopts a very different orbit from Chang'e-3.

Although on the map, the difference is very small at the beginning, the difference continues to increase, and the final result is a very considerable error.

It not only saves time and fuel, but also accumulates richer experience for future lunar exploration projects, which is much more important than Chang'e 4 itself.

Although the moon is only 384,000 kilometers away from the earth and is a satellite of the earth, this distance is still so far away for humans.

So far, only the United States, Russia, and China have the right to launch probes to the moon. Other countries have undoubtedly failed to rely on themselves.

When Qin Yuanqing saw that the second stage was successfully completed, a smile appeared on his face. Everything went according to his settings.

After completing this stage, Qin Yuanqing temporarily left, because from orbiting the moon to setting the moon, it takes a total of 10 days to orbit the moon, and he will enter this stage after 10 days.

Because Chang'e-4 will orbit the moon for 10 days to conduct further exploration of the moon, because this time's orbit around the moon is the same as the previous three.