Chang'E Goes To The Moon Again: China Opens A New Chapter In Lunar Exploration

At 4:30 on November 24, the Long March 5 rocket carrying chang'e-5 was successfully launched. It is reported that chang'e-5 will carry out China's first lunar sampling and returning mission, which is one of the most complex and difficult space missions in China so far.

According to field reports, after the launch of the long March-5 remote-5 launch vehicle, four separations were carried out, including booster separation, fairing separation, primary and secondary separation and rocket separation.

"Chang'e" to the moon

The earliest history of China's preparation for lunar exploration project can be traced back to the 1990s, when demonstration work was mainly carried out. Until January 2004, the lunar exploration project was officially approved and named "Chang'e project".

The successful launch of the "Chang'e" orbiter in the first month of 2007 means that the "orbit around the moon" of the "Chang'e" spacecraft has been successfully completed in one month and three months in 2007.

In 2008, the second phase of the lunar exploration project was approved and entered the implementation stage. The second phase project includes two missions of "Chang'e-2" and "chang'e-3". The main objectives of the project are to realize the soft landing of the moon, as well as to carry out the exploration and exploration of the lunar surface.

In October 2010, "Chang'e-2" was launched as the pilot satellite of "chang'e-3". Chang'e-2 is mainly used to carry out advanced verification of some technologies, including direct lunar orbit, X-band TT & C and detailed survey of pre selected landing area.

After "Chang'e-2" finished the first battle, in December 2013, the "chang'e-3" probe successfully landed in the pre selected area of the moon, realizing the soft landing and patrol survey of Chinese spacecraft for the first time, and also marked the completion of the "moon landing" goal of the second phase of the lunar exploration project.

In 2009, with the implementation of the second phase of the lunar exploration project, the third phase of the lunar exploration project was officially opened, mainly for the demonstration and research of "chang'e-5". By 2011, the third phase of the project has been officially approved, and the mission goal is to achieve unmanned sampling return on the lunar surface.

In fact, before the launch of chang'e-5, China carried out the lunar earth high-speed reentry and return mission to verify the key technology of semi ballistic jump reentry. The mission was successfully launched in May 2014, laying the foundation for the launch of Chang'e high-speed return to earth in May 2014.

If the "chang'e-5" mission can be successfully completed, it will also mean the realization of the three objectives of the lunar exploration project.

Some people may wonder where chang'e-4 has gone. An aerospace expert once told reporters that each phase of the lunar exploration project will carry out "one main and one standby", which is to prevent the overall plan from being delayed due to emergencies.

Therefore, the lunar exploration project is actually designed with three satellites, namely, Chang'e-1, chang'e-3, and chang'e-6, which are used as backup satellites.

The mission of chang'e-3, which is the first time for the lunar exploration mission of chang'e-3, has been successfully completed since the lunar exploration mission of "chang'e-3". On December 8, 2018, "chang'e-4" was successfully launched, and on January 3, 2019, it successfully landed in the pre selected landing area on the back of the moon.

This time there will be a return

Chang'e-5 is the main mission of the third phase of the lunar exploration project. It will verify the main key technologies of manned lunar landing in addition to the survival of astronauts, including lunar surface sampling, lunar surface takeoff, lunar orbit rendezvous and docking, high-speed earth atmosphere reentry and return, etc.

It is reported that the chang'e-5 probe consists of a lunar orbiter, a lander, an ascent and a reentrant. The whole mission process includes 11 stages: launch, Earth Moon transfer, near moon braking, circumlunar flight, landing descent, lunar surface work, lunar takeoff and ascent, rendezvous and docking and sample transfer, lunar waiting, lunar earth transfer and reentry recovery.

According to the information previously released by the National Space Administration, at about 18:30 on November 23, the Long March 5 remote-5 launch vehicle began to fill with liquid oxygen and liquid hydrogen low-temperature propellant, and the launch mission was planned to take place from 4:00 to 5:00 a.m. on November 24.

The reason why there is a launch interval of nearly one hour is because of the complicated pre launch operation and the complex meteorological conditions of Shanghai South launch site, it is necessary to maintain a certain launch window width to reduce the project risk. Therefore, the launch vehicle adopts the method of 5 trajectories and each trajectory covers 10 min launch window width to meet the requirements of 50 min launch window and the limitation of ± 5 min launch orbit correction ability of the detector system.

In addition, due to the limitation of launch quality of launch vehicle, the optimal trajectory of incident energy with flight time of about 5 days is selected for both Earth Moon and lunar earth transfer orbits. In order to reduce the requirement of re-entry, the moon earth transfer incident opportunity is selected in the days before and after the moon is the southernmost latitude relative to the earth, and the sampling area is determined as the largest lunar storm ocean area in front of the moon.

In addition to the goal of unmanned lunar surface sampling and return, chang'e-5 also has two major scientific objectives, including on-site investigation and analysis of landing area and analysis and research of lunar samples. Therefore, chang'e-5 is also equipped with four scientific detection payloads, including landing camera, panoramic camera, lunar mineral spectrum analyzer and lunar soil structure detector, to realize multi spectral detection of visible light, infrared and microwave.

From 1958 to 1976, the two camps represented by the United States and the Soviet Union launched a space race, and set off a round of lunar exploration climax. During this period, the two countries carried out 100 unmanned explorations, including 64 in the former Soviet Union and 36 in the United States. In addition, the United States has carried out nine Apollo manned explorations, including two manned lunar circumnavigation and seven manned lunar landings.

Through these exploration activities, the United States has collected 385kg lunar samples, while the former Soviet Union has obtained 375g lunar samples. Through these samples, both countries have obtained a large number of original data of lunar scientific exploration.

In the following 40 years, the exploration of the moon continued in many countries, but it was mostly around the moon. Last year, the soft landing of chang'e-4 on the moon has made China the third country to land on the moon after the United States and the Soviet Union. This time, chang'e-5 plans to bring back 2kg samples from the moon. If successful, China will retrieve the first lunar rock in 40 years.

Wu Yanhua, deputy director of the National Space Administration and Deputy commander-in-chief of the lunar exploration project, once said that China's lunar exploration project will enter the follow-up stage of lunar exploration after the completion of the three stages of the Chang'e project.

In addition to the chang'e-4 mission that has already been implemented, NASA is also organizing domestic experts to demonstrate the follow-up planning of the fourth lunar exploration phase. It is basically clear that there are three missions:

One is chang'e-6, which plans to return to the south pole of the moon. As for whether it is on the back or the front, it should be determined according to the sampling situation of chang'e-5;

Second, chang'e-7 plans to conduct a comprehensive exploration in the south pole of the moon, including the topography, material composition and space environment of the moon;

The third is chang'e-8. In addition to continuing scientific exploration experiments, chang'e-8 will also carry out lunar surface tests on some key technologies as the preliminary exploration for the establishment of a scientific research base on the moon in the future.

The closest distance between the moon and the earth is also the starting point for human exploration of the universe. In the past 20 years, China's lunar exploration project has achieved five battles and five victories. Now, we are waiting for the good news of chang'e-5's successful return. At that time, China will also open a new chapter in lunar exploration.

?