Chang'e 4, ChinaLunar exploration projectThe lunar probe launched in the second phase is also the first human probe to land on the back of the moon;Realized the first soft landing and patrol survey on the back of the moon, which is of great significance and far-reaching impact[1-2]。
Chang'e-4 was launched on December 8, 2018;The near moon braking was completed on December 12, 2018, and was captured by the moon;Landing at the pre selected area on the back of the moon on January 3, 2019[3]；On January 11, 2019 and“Yutu No. 2”Complete the mutual shooting between the two devices[4]。
As of September 29, 2021, on the occasion of the 72nd birthday of the motherland, the Chang'e-4 lander and Yutu 2 rover have been in orbit for more than 1000 days, continuing to set new records for work on the back of the moon.The Chang'e-4 lander and the Yutu 2 lunar rover are in good working condition, and their loads are working normally. They continue to carry out scientific exploration.[5][31]On January 3, 2022, the third anniversary of Chang'e-4's landing, 3780GB of exploration data were obtained[33]。
On November 30, 2015, the State Administration of Science, Technology and Industry for National Defense organized the 14th meeting of the major special leading group of the lunar exploration project to review and approve the report on the adjustment of the implementation plan of the Chang'e-4 mission, the general requirements for research and development and the overall follow-up research and development plan[6]。
On January 14, 2016, the Chang'e-4 mission was reviewed and implemented by the major special leading group of the lunar exploration project.
On April 24, 2018, the Chang'e-4 relay star was named "Queqiao"[7]。
On May 21, 2018, China successfully launched the Queqiao relay satellite of the Chang'e-4 mission from the Xichang Satellite Launch Center with the Long March 4C carrier rocket.
On May 25, 2018, the moon exploration project Chang'e-4 mission "Queqiao" relay star successfully implemented the near moon braking, entering the transfer orbit from the moon to the Earth Moon Lagrange L2 point.
On June 14, 2018, the moon exploration project Chang'e-4 mission "Queqiao" relay satellite successfully implemented orbit capture control, entered the Halo mission orbit around the Earth Moon Lagrange L2 point about 65000 kilometers away from the moon, and became the world's first satellite operating in the Earth Moon L2 point Halo orbit.
On June 14, 2018, the relay star "Queqiao" entered its mission orbit.
On August 15, 2018, Chang'e-4 announced the appearance of the lander and lunar rover, and conducted a global naming campaign[8]。
On October 25, 2018, the Lunar Exploration and Space Engineering Center of the State Administration of Science, Technology and Industry for National Defense and the General Department of Lunar and Deep Space Exploration of the Chinese Academy of Sciences jointly organized a scientific seminar on the Chang'e-4 mission in Beijing[9]。
Chang'e-4 Launch Map 2
On December 8, 2018, Chang'e-4 was launched[10]。
On December 12, 2018, Chang'e-4 completed the braking near the moon, was captured by the moon, and entered the lunar orbit of about 100 kilometers near the moon point[11]。
On December 30, 2018, the Chang'e-4 probe completed the implementation of the lunar orbit lowering control[12]。
On January 3, 2019, Chang'e-4 landed on the back of the moon, and then the lander was separated from the rover for in place and patrol detection[13]；On the same day, Chang'e-4 announced the results of the lunar rover naming campaign and named it "Yutu 2"[3]。
On January 11, 2019, Chang'e-4 and "Yutu 2" completed the mutual shooting of the two vehicles[4]。
On January 14, 2019, Chang'e-4 and Yutu 2 probes went into hibernation[14]。
On March 30, 2019, Chang'e-4 wakes up, the forward return link of the relay is established normally, and the platform works normally[15]。
On June 9, 2019, Chang'e-4 completed its lunar night setup and entered the sixth lunar night dormancy period[16]。
On January 15, 2022, the Chang'e-4 probe went into lunar sleep again, and all systems were in good conditionOK.[35]
The lunar rover and lander of Chang'e-4 mission "Yutu 2" will complete their sleep settings at 19:14 on July 5, 2022 and 6:00 on July 6, 2022, respectively. They will complete their work in the day of the 44th month and enter their sleep in the 44th night of the month.The accumulated mileage of the rover on the back of the moon is 1239.88 meters.[40]
Queqiao 2 relay satellite is planned to be launched in 2024. As a public relay satellite platform for the fourth phase of lunar exploration, it will provide relay communication services for Chang'e-4.[45]
flying commission
Announce
edit
Flight plan
1. The relay satellite was launched in advance and put into a predetermined orbit, and then Chang'e-4 was launched by rocket.
2. Chang'e-4 completed the earth moon transfer, near moon braking, and circumlunar missions.
3. Soft landing on the back of the moon, positioning and patrol exploration on the back of the moon;4. Relay communication between the back of the moon and the diameter of the earth is realized through relay satellites that have been in real name orbit[17]。
Schematic Diagram of Chang'e-4 Flight Orbit
Main tasks
1. We will carry out exploration activities such as lunar surface topography and geological structure, mineral composition and chemical composition, lunar internal structure, earth moon space and lunar surface environment, and build a basically supporting lunar exploration engineering system.
2. To explore the back of the moon, especially the largest known crater in the solar system.
3. Try the relay communication on the back of the moon.
4. The world's first low-frequency radio astronomy observation[18]。
Mission objectives
Project objectives
1. Develop and launch the lunar relay communication satellite to achieve the first international measurement and control and relay communication of the Earth Moon Lagrange L2 point;
2. Develop and launch lunar landers and rovers to achieve the first international soft landing on the back of the moon and patrol exploration[19]。
Scientific objectives
1. To carry out low-frequency radio astronomy observation and research on the back of the moon;
2. To carry out exploration and research on the topography, mineral composition and shallow structure of the lunar surface in the patrol area on the back of the moon;
3. Experimental research on lunar environment such as neutron radiation dose and neutral atom on the back of the moon[19]。
Task characteristics
1. Chang'e-4 needs to accomplish its scientific goal on the back of the moon.
2. The engineering goal of Chang'e-4 mission is targeted at two "firsts".
3. Chang'e-4 carried eight payloads to the Von Karman impact crater on the back of the moon.
4. Chang'e-4 needs to deal with the rugged terrain on the back of the moon to achieve more difficult precise control.
5. Chang'e-4 needs to implement the "relay" of communication signals with the ground through the relay satellite to connect with the earth[20]。
Landing data
On January 3, 2022, it was reported that on January 3, 2019, the Chang'e-4 probe successfully landed at the bottom of the Von Kamen impact crater in the Antarctic Aitken basin on the back of the moon, carrying out the first lunar back exploration in human history.According to the data released by the Moon Exploration and Space Engineering Center, the Chang'e-4 Magpie Bridge relay satellite has been in orbit for 1322 days;1096 days of work on the back of the rover and lander;Totally 3780GB of detection data is obtained;The Yutu 2 lunar rover has a journey of 992.33 meters.[33]On January 6, 2022, the driving distance of the Yutu II lunar rover will exceed 1000 meters, reaching 1003.9 meters.In the daytime working period of the 38th monthNot at all.[34]
Chang'e-4 driving track
Driving in the daytime in 41 months in front of Chang'e-4road map[37]
In July 2022, the lunar rover and lander of Chang'e-4 mission "Yutu 2" will complete their sleep settings at 19:14 on July 5 and 6:00 on July 6, respectively, completing the day work in the 44th month and entering the 44th lunar night sleep.The accumulated mileage of the rover on the back of the moon is 1239.88 meters.[39]
Chang'e-4 driving track
international co-operation
On March 3, 2022, the ground application system of the lunar exploration project publicly released the twelfth batch of scientific data of Chang'e-4 international cooperative payload.[36]
On February 15, 2023, the ground application system of the lunar exploration project publicly released the 22nd batch of scientific data of Chang'e-4 international cooperative payload.[44]
Scientific data
On February 15, 2023, the ground application system of the lunar exploration project publicly released the 34th batch of scientific data of Chang'e-4.[44]
system composition
Announce
edit
System overview
The Chang'e-4 mission consists of five systems, namely, the overall engineering and the detector, carrier rocket, launch site, measurement and control, and ground application[21]。
Main systems
The main task of the probe system is to develop the Chang'e-4 lunar probe, which consists of a relay satellite, a lander and a rover[22]。
name
introduce
Concept Map
tdrss
It is named "Queqiao".According to the requirements of the soft landing exploration mission on the back of the moon of Chang'e-4, after the separation of Queqiao and the carrier rocket in the earth moon transfer orbit, it needs to use its own propulsion system to realize the transfer to the earth moon L2 libration point, complete the acquisition and correction of the orbit of the earth moon L2 libration point halo mission, and operate stably in this orbit for a long time;Queqiao will provide forward/backward time and delay relay communication between the Chang'e-4 lander on the back of the moon, the rover and the ground station, and the satellite's in orbit service life will reach more than 3 years.
tdrss
Lander
The mission process of Chang'e-4 lander includes five parts: launch phase, earth moon transfer phase, circumlunar phase, power descent phase, and lunar surface working phase. In the first three stages, the TT&C communication system completes the TT&C task through the direct ground link.
The latter two missions need to be carried out on the back of the moon, and relay satellites are required to provide relay and forwarding services for them to cooperate with them to complete relevant exploration tasks.
Lander
rover
It is named "Yutu No. 2".The overall scheme of Chang'e-4 is inherited from that of Chang'e-3, which is divided into eight subsystems, namely, mobility, structure and mechanism, guidance navigation and control (GNC), integrated electronics, power supply, thermal control, measurement and control data transmission and payload.The configuration of the inspector is still box plate structure, and the configuration of the inspector in moving state.
rover
reference material:[22-24]
Delivery system
The main task of the launch vehicle system is to develop the Long March 3B launch vehicle and launch it at Xichang Satellite Launch Center[22]。
Launch system
Organized and implemented by Xichang Satellite Launch Center to undertake the Chang'e-4 launch mission[22]。
Measurement and control system
The main tasks of the TT&C system are the TT&C, orbit measurement and determination, lunar surface target positioning, and the control of the lander and lunar surface rover after the moon falls[22]。
Ground applications
Responsible for the scientific exploration plan formulation of Chang'e-4 probe, payload operation management, and receiving the detection data of lander and rover through the relay satellite[22]。
At 8:31 on March 20, 2024, the fourth phase of the lunar exploration project, Queqiao 2 relay satellite, was successfully launched from the Long March 8 Yao-3 carrier rocket at Wenchang Space Launch Site, China.As the "key link" of the follow-up task of the fourth phase of the lunar exploration project, the Queqiao II relay satellite will build a new "Queqiao Bridge" to provide earth moon relay communication for Chang'e-4, Chang'e-6 and other missions.[46]
At 0:46 on March 25, 2024, after about 112 hours of flying to the moon, the Queqiao 2 relay star began to apply the near moon braking at about 440 kilometers from the moon surface. After about 19 minutes, it successfully entered the lunar orbit.Later, the Queqiao 2 relay satellite will enter the round moon large elliptical mission orbit with a 24-hour cycle by adjusting the height and inclination of the lunar orbit, and carry out the communication test with Chang'e-4 and Chang'e-6 as planned.[47]On April 6, the Queqiao II relay satellite successfully communicated with Chang'e-4, which is carrying out exploration missions on the back of the moonTest.[48]
technological innovation
Announce
edit
key technology
1. A new design scheme is adopted to create a new supporting circuit for the core component quartz flexible accelerometer, which improves its reliability.
2. The γ shutdown sensor can accurately measure the distance in the near moon environment, and accurately turn off the orbit control and attitude control engines, effectively ensuring the success of the first soft landing of Chang'e-4 on the moon back.
3. The connection unlocking mechanism was used to enable the Yutu 2 and Chang'e 4 landers to be separated accurately and set foot on the moon for scientific research missions.
4. Two kinds of motors are customized, one for wheel drive and steering drive, and the other for joint drive of manipulator subsystem.
5. Provide SAW device products, crystal component products, battery packs, connectors, relays, metal hoses, fasteners and other core technologies, and establish a life-cycle, traceable and traceable electronic file[25]。
Technical breakthrough
1. It is the first time to realize soft landing and patrol exploration on the back of the moon;
2. It is the first time to realize the relay, measurement and control communication between the back of the moon and the earth;
3. It was the first time to realize the VLF scientific exploration of the lunar rear lander and lunar orbit microsatellite at that time, and the launch and orbit entry accuracy of the launch vehicle with multiple windows and narrow widths reached the international advanced level;
4. It is the first time to carry out the laser ranging technology test beyond the earth moon distance;
5. It is the first time to carry out biological science popularization on the moon;
6. First international cooperative load carrying and joint detection[4]。
Chang'e-4 Launch
Scientific experiment
1. Using the in place detection data of the lunar radar, the geological stratification structure within the depth of 40 meters below the landing area on the back of the moon is revealed for the first time, and its material composition and evolution mechanism are expounded.
2. Using the in place spectral detection data of infrared imaging spectrometer, the material composition of the back of the moon was successfully revealed, which verified that the moon mantle is rich in olivine, and deepened human understanding of the formation and evolution of the moon.
3. The energy spectrum of energy neutral particles on the lunar surface is obtained by using the detection data of energy neutral atoms in the lunar surface environment from the neutral atom detector, which confirms that the energy of energy neutral particles has a strong correlation with the speed of the incoming solar wind.
Scientific research achievements
Study on the Morphology and Mineral Composition of the Patrol Area on the Back of the Moon
1. Using the data of visible and near infrared spectrometers, panoramic cameras and lunar radars carried by the "Yutu II" lunar rover, the spectrum, rock distribution, shallow structure, etc. of the land area were analyzed, and scientific conclusions such as the landing area morphology, material mineral composition, source and characteristics were obtained.
2. It is the first time to directly obtain the composition of the deep lunar material through in-situ exploration, reveal the complex impact history of the back of the moon, especially the Aitken Basin in Antarctica, provide key evidence for the formation and evolution model of lunar soil, and provide important reference for future Antarctic landing and patrol exploration site selection.
Study on the shallow structure of the lunar surface in the inspection area on the back of the moon
1. Based on the lunar radar and camera data of the Chang'e-4 lander and other multi-source data, the stratigraphic profile of the Chang'e-4 landing area and the multi period sputtering coverage relationship are studied and established.
2. The accumulated thickness of the sputtering material in the landing area is about 70 meters, and the surface is the Fensen impact crater sputtering material;Within the depth of 40 meters in the patrol area, there are three different stratigraphic units, including the fine-grained lunar soil layer within 12 meters, the gravel layer between 12 meters and 24 meters, and the sputtering deposit and weathering product layer between 24 meters and 40 meters.
Results The mystery of the underground structure on the back of the moon was revealed for the first time, which greatly improved human understanding of the history of lunar impact and volcanic activity, and brought new enlightenment to the study of geological evolution on the back of the moon.
Study on Neutron, Radiation Dose and Neutral Atom on the Lunar Surface
1. Using the lunar surface neutron and radiation dose detector and neutral atom detector of Chang'e-4 lander, the radiation environment spectrum of energetic particles on the lunar surface, the energy spectrum structure and albedo of neutral atoms on the lunar surface were obtained.
2. The neutron radiation dose rate on the lunar surface is 1 to 2 times higher than that inside the space station, and the radiation dose equivalent is about 1 time higher.It is confirmed that primary galactic cosmic rays hit the surface of the moon, producing reflected protons (first found on the US lunar orbiter, and this time it was verified on the moon surface).
3. The results provide important support for the research on the micro interaction between the solar wind and the moon surface, promote the cognition of the radiation risks on the moon surface, and provide important reference for the estimation of the radiation hazards on the moon surface and the radiation protection design of the future lunar astronauts.
Low frequency radio astronomy observation and research based on the moon
1. Using the low-frequency radio spectrometer of Chang'e-4 lander platform, low-frequency radio astronomy observations were successfully carried out on the back of the moon for the first time, and a large number of effective observation data were obtained.
2. The preliminary acquisition of the background spectrum of the electromagnetic environment and the low-frequency radio three component time-varying waveform data in the lunar land area below 40 MHz has important scientific significance for the study of the solar low-frequency radio characteristics and the low-frequency radio environment on the lunar surface[26]。
On May 5, 2022, the ground application system of the lunar exploration project publicly released the 26th batch of scientific data of Chang'e-4, which was provided by the ground application system, including the scientific data obtained by three scientific loads carried on the Chang'e-4 lander and rover (Yutu 2 lunar rover) during the thirtieth day (2021.05.05-2020.05.19), a total of 93 data files,The total data is 2092.05 MB.[38]
In July 2022, the latest research results of Chang'e-4 were announced. Recently, the Chinese scientists team analyzed the data obtained by the Yutu 2 lunar rover and found that at the bottom of the Antarctic Aiken Basin, the largest impact basin on the moon, the plagioclase content as the main mineral of the moon shell exceeded 60%, so it is believed that the moon shell is the main material source of this abnormal composition area.This discovery provides a new basis for the follow-up exploration and research of the moon.[41]
Honors won
Announce
edit
Project (team) name
Awards won
China's Chang'e-4 lunar exploration mission
Excellent lunar exploration mission of the 3rd International Lunar Village Seminar in 2019
2020 American Space Foundation Gold Award
Chang'e-4 mission team
2019 Royal Aeronautical Society Team Gold Award
Chang'e-4 Project
Special Prize of National Science and Technology Progress Award in 2020
reference material:[27-28][32][42-43]
Overall evaluation
Announce
edit
The establishment and implementation of the Chang'e-4 mission is a major decision made by the CPC Central Committee to develop the space industry and build a powerful aerospace country, a specific action to implement the guiding spirit of the General Secretary's "promoting the comprehensive development of space science, space technology and space applications", a major Chinese aerospace project that has attracted worldwide attention, and a demonstration project for open cooperation in the aerospace field,It is a landmark project connecting the past and the future in the field of lunar exploration, with great political and practical significance[29]。（Zhang Kejian, then Deputy Director of the State Administration of Science, Technology and Industry for National Defense)
The complete success of Chang'e-4 mission has achieved the soft landing and patrol survey of spacecraft on the back of the moon for the first time in human history, achieved the first measurement and control communication between the earth and the back of the moon, left the first footprint of China's lunar exploration on the back of the moon, opened the mysterious veil of the ancient moon back, and opened a new chapter in human exploration of the mysteries of the universe[30]。(Evaluated by the Central People's Government of the People's Republic of China)
