According to Xinhua News Agency, this is the first time that mankind has unveiled the mystery of the ancient moon back. At 10:26 on January 3, 2019, the Chang’e-4 probe landed independently in the von Carmen impact crater in the Antarctic-Aitken Basin on the back of the moon, realizing the first soft landing of the human probe from the back of the moon.
After about 380,000 kilometers and 26 days of long flight, Chang’e-4 entered the moon-falling orbit 15 kilometers away from the moon surface. In the lobby of the Beijing Space Flight Control Center, with the command of the on-site working personnel, the Chang’e-4 probe began to decelerate from 15 kilometers away from the moon, and the speed of the probe gradually dropped from 1.7 kilometers per second to zero from the moon.
At 6 to 8 kilometers, the detector makes rapid attitude adjustments and constantly approaches the moon; starts hovering 100 meters away from the moon surface, identify obstacles and slopes, and avoid obstacles independently; after selecting a relatively flat area, Komiks, it begins to slowly and vertically descend. Finally, under the “escort” of the reverse thrust engine and landing buffer mechanism, a more than one ton of detector successfully landed in a pre-selected landing area near 177.6 degrees east longitude and 45.5 degrees south latitude.
The Chang’e-4 landing area has a terrain of 6,000 meters. It is one of the largest known impact craters in the solar system and is considered to be of great value to study the early history of the moon and solar system. After the moon set, through the “macaoqiao” relay star, the Chang’e-4 probe carried out a number of tasks such as solar wings and directional antenna deployment, and established a high-code rate link for directional antennas, achieving the “small goal” of stable communication between the back of the moon and the ground.
At 11:40, the Chang’e-4 lander obtained the image of the back of the moon and sent it back to the ground. This is the first image taken by a human probe on the back of the moon.
At 15:7, staff sent instructions to Chang’e-4 through the “Queqiao” relay star at the Beijing Space Flight Control Center, and the separation of the Chang’e-4 lander and the Yutu-2 cruiser (i.e., the lunar rover) began.
On the large screen in the flight control hall, the Chang’e-4 lander stands on the moon, and the sun’s wings are unfolding. Jade Rabbit Number TwoThe inspector Babaylan stands on the top of the lander, spreads the sun’s wings and extends the mast. Then, the patrol began to move slowly towards the transfer mechanism. The transfer mechanism was unlocked normally. An inclined ladder was set up between the lander and the moon, and the patrol slowly walked towards the moon along the inclined ladder. At 22:22, the patrol stepped onto the surface of the moon, and the patrol left the first mark on the back of the moon.
Image image of the moon taken by the landing camera of the power descent of the Chang’e-4 probe
Revealed the 7 major highlights of Chang’e-4
Only landing in the mountains and ridges, exploring the origin of the universe, and “planting potatoes” on the moon…
Text/Pic Xinhua News Agency
The Chang’e-4 probe, which took off from the Xichang Satellite Launch Center on December 8, 2018, finally waited for the destination Antarctic-Aitken Basin, the largest, deepest and oldest crater in the solar system, ushered in dawn.
At 10:26 on January 3, 2019, the Chang’e-4 probe Komiks landed independently in the von Carmen impact crater in the Antarctic-Aitken Basin on the back of the moon, realizing the first soft landing of the human probe from the back of the moon. At 11:40, the Chang’e-4 lander obtained the first image of the back of the moon and sent it back to the ground.
1
How to achieve “autonomous driving”?
Use the “brain” calculation to find the landing point
At 10:15 on January 3, with the assistance of communications from about 65,000 kilometers away from the moon, orbiting the second Lagrangian point of the Earth and the moon, and seeing the Earth and the back of the moon at the same time, the variable thrust engine on Chang’e-4 was ignited, and the speed of the probe dropped from 1.7 kilometers per second to close to zero. The detector adjusted its posture and landed vertically towards the relatively flat bottom of the von Carmen impact crater in the Aitken Basin.
When it was about two kilometers away from the moon surface, the projection formed by the sun shining on the moon surface from the east was captured by the camera on the detector. After processing by the computer’s “brain”, it identified the large rocks and craters below and performed its first obstacle avoidance.
When it is 100 meters away from the moon, it hoveres in the air, and uses laser scanning to identify smaller obstacles and slopes on the moon.Its “brain” calculates again, finding a safer location as the landing site.
When two meters away from the moon, the engine on the detector stopped working, and the golden lander holding the rover fell down with its own gravity. The four legs stood firmly on the desolate gray moon surface, raising a piece of moon dust.
The entire landing process lasted about 12 minutes, and it was completed independently by the detector. There was no intervention on the earth, but the “Magpie Bridge” sent the landing back to the command and control center in the suburbs of Beijing.
2
How to land in the mountains?
The probe automatically identifies obstacles and avoids obstacles
Wu Weiren, chief designer of China’s lunar exploration project, compared it to: Chang’e-3 is like landing on the North China Plain, while Chang’e-4 is like landing on the steep mountains in southwest China.
He said that the Chang’e-4 landing area is equivalent to one-eighth of the Chang’e-3 landing area, and there are mountains 10 kilometers above sea level around the landing area. The Von Carmen impact crater in the Aitken Basin is minus 6 kilometers above sea level, so unlike the smooth parabolic landing trajectory of Chang’e-3, Chang’e-4 is approaching a vertical landing.
“The landing time is short, difficult and high risk is a great test for us,” said Wu Weiren. Sun Zezhou, chief designer of the Chang’e-4 probe of the Fifth Academy of the Aerospace Science and Technology Corporation, said: “Our information on the lunar terrain mainly comes from previous remote sensing data around the lunar lunar lunar lunar lunar lunar lunar remote sensing data, including remote sensing data of Chang’e-1, Chang’e-2 and some foreign satellites. However, these data cannot provide us with sufficient accuracy terrain information. We cannot know where there are big stones, but it is more of the overall macro information and statistical probability. In the end, the landing still depends on the probe to independently identify obstacles and avoid obstacles.” Zhang Ying, project director of the Chang’e-4 probe of the Fifth Academy, said that Chang’e-4 considered how to improve the accuracy of the landing in the system design, added orbit corrections during the lunar lunar lunar phase, and adjusted the power decline control strategy. The detector must reach above the landing area when it is relatively high from the lunar surface and then descend vertically, so that the complex and rugged terrain on the track will not have an impact on the landing.
3
What is the significance of exploring the back of the moon?
Glance to the origin of the universe after the Big Bang
“The risk of going to the back of the moon is much greater than that of the front. The rugged terrain brings us the problems we must face, but a higher precision landing on the moon is needed in the future. Solving the challenges facing this mission can lay the foundation for subsequent deep space exploration and asteroid exploration. We hope to have the ability to reach the entire moon and even the entire solar system in the future.” Sun Zezhou said.
Zou Yongliao, director of the General Department of Lunar and Deep Space Exploration of the Chinese Academy of Sciences, said that the back of the moon has its own unique position.Features Babaylan, Chang’e-4 landed in a virgin land that had never been explored on the spot, and may be able to obtain important discoveries.
For astronomers, the back of the moon is a rare place of tranquility, because the moon itself blocks various radio interference signals from the earth, where it may see how the universe escapes from the darkness and lights up the first generation of stars after the Big Bang.
4
Why did it land at the Von Carmen crater?
The pits here are still “mysteries”. Due to tidal locking, the moon orbits the earth and its rotation period is the same. The bright “view” of the moon seen from the earth is always the same. In the era without space probes, the back of the moon has always been a mysterious unknown world.
It was not until about 60 years ago that the Soviet Union’s Moon 3 probe sent back the first image on the back of the moon. About 50 years ago, three astronauts from the United States, Apollo 8, became the first human to witness the back of the moon while flying around the moon.
More and more probes around the moon have made people discover that the back and front of the moon are so different: the front is relatively flat, while the back is rugged and full of bumpy impact craters; the lunar crust on the back of the moon is much thicker than the front. Why is this happening? It is still a mystery now, and only landing detection can reveal this mystery.
The exploration of the von Carmen impact cratersKomiksThe Babaylan has another meaning, and it was named after the 20th-century Hungarian-American aerospace engineer Von Carmen. Qian Xuesen and Guo Yonghuai, the founders of China’s aerospace industry, are both personal disciples of this “science genius in the aerospace era”.
5
What surprises will this detection bring?
They will prepare for the return of humans to the moonKomiks
It has been 50 years since humans first landed on the moon. Can humans return to the moon? How much impact will radiation on the moon have on astronauts? How much water is there on the moon? How does the water on the moon come from? Chinese and foreign scientists will find the answer through Chang’e-4 to prepare for humans to return to the moon.
Wen Mu, chief project manager of the Institute of Physics Experimental and Applications of Kiel University in Germany, said: “When the astronauts return to Earth, the radiation caused by Komiks on the moon remains in their bodies. This is a persistent danger, so we must understand these radiation.” “The childhood experiences of the moon have also happened on Earth. But due to geological activities, traces of the earth’s early years have been erased. To understand the long-standing past of the earth, the moon may give us an answer.” said Lin Yangting, a researcher at the Institute of Geology and Geophysics, Chinese Academy of Sciences.
6
What scientific research tasks are there?
Testing the “body temperature” for the moon “planting flowers”
The Chang’e-4 mission carried the Komiks detector developed by Chinese and Dutch scientists. “Cinema is the dream of astronomers in Komiks to the back of the moon, and can fill the gap in the low-frequency observation segment in the field of radio astronomy,” said Zou Yongliao.
Chang’e-4 also brought six organisms, cotton, rapeseed, potatoes, Arabidopsis, yeast and fruit flies to the inanimate moon, forming a microbiosphere. People look forward to the first flower blooming on the moon. Chinese scientists have no exact data on how cold the moon is at night. The Chang’e-4 mission also includes measuring the “body temperature” of the moon. Shin Zhenrong, the designer of the Chang’e-4 cruiser of the Fifth Academy, said that going to the back of the moon is China’s contribution to the world. “Although we don’t know what we can detect in the end, this detection may affect generations.”
7
What international cooperation projects are there?
Enabled scientific loads from four countries
In order to enhance international exchanges and cooperation and expand openness and sharing, Chang’e-4 not only carries China’s experimental projects, but also carries the scientific loads from the Netherlands, Germany, Sweden and Saudi Arabia.
Korel, director of the Department of Solar Systems Science of the Swedish Space Agency, said the first soft landing on the back of the moon was a huge achievement for China, and “we are very happy to be part of this mission.” He said:”There is a theory that water on the moon is generated by the interaction between the solar wind and the weathering layer on the moon’s surface. This is a question that Swedish and Chinese scientists want to answer through exploration.” The Chang’e-4 probe is also equipped with a lunar neutron and radiation dose detector developed by Kiel University in Germany. The total weight of the instrument is about 3 kilograms and can comprehensively measure the radiation environment of neutrons and other particles on the moon’s surface.
Robert Wimmer-Schweiingruber, head of the Chang’e-4 German Science Payload Project Team and Professor at Kiel University, said: “China is working with many international partners, and it is becoming more and more cooperation. I don’t agree with the practice of refusing to cooperate because of fear of technology outflow. In my opinion, technology will only die out because of refusal to share. “