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Chinanews.com, Beijing, December 6, Title: For the First Time Through 380,000 Kilometers of Microwave Radar Encounter and Docking to Help Chang’e-5 “Move in Space”
Author Guo Chaokai
On December 6, the Chang’e-5 probe successfully completed the first unmanned encounter and docking of China’s lunar orbit. The Chang’e-5 docking and meeting microwave radar developed by China Aerospace Science and Industry Corporation, as the only long-distance measurement means of the probe in lunar orbit, successfully guided the Chang’e-5 to perform the first unmanned encounter and docking in lunar orbit. Docking technology is one of the “four key technologies” on the Chang’e-5 mission.
The orbiter gradually moves closer to the ascendant Image source: China National Space Administration
See more clearly and accurately
The Chang’e-5 docking and meeting microwave radar is a pair of products consisting of a main radar and a transponder, which are installed respectively in the orbiter and the ascendant of the Chang’e-5 detector. When the orbiter and the ascendant are about 100 kilometers apart, the microwave radar begins to operate, constantly providing the navigation control subsystem with the relative motion parameters between the two spacecraft and conducting two-way air-to-air communication. . The two spacecraft adjust their flight attitude according to the signals provided by the radar until the orbiter’s docking mechanism captures and locks the ascendant. Subsequently, the lunar soil samples and containers were transferred into the ascendant.
Sun Wu, Chief Encounter and Docking Engineer for Microwave Radars at the 25th Institute of the Second Academy of China Aerospace Science and Industry Corporation, reported that in previous manned space engineering missions, Chinese spacecraft had conducted encounters and couplings in low Earth orbit many times, all of which used the microwaves of aerospace science and industry. Radar. The performance of the five battles and the five victories is enough to show that China has successfully mastered the technology of encounter and docking. But the difference is that this time it is in the lunar orbit, which is 380,000 kilometers away, which is more difficult.
The Chang’e 5 Orbital Encounter and Docking Microwave Radar team conducts a state inspection before the product leaves the factory Image source: China Aerospace Science and Industry Corporation
“Compared to low Earth orbit, lunar orbit does not have service resources such as satellite navigation, and microwave communication is the only medium for medium and long distances. The lunar orbit environment is more complex and must overcome the influence of lunar gravity, so that automatic docking and rendezvous places require extremely demanding requirements for microwave radars. To this end, microwave radar equipment has surpassed key technologies such as interferometer angle measurement of phase and wide angle measurement, “Sun Wu said.
Also, the elevator equipped with the transponder for docking will inevitably form dust when the moon is falling. Interference from moon dust that is invisible to the naked eye will seriously reduce the accuracy of the angle measurement. To ensure a safe trip across the moon, a dust cover made of special materials is installed on the transponder. “It’s like putting on ‘goggles’ for clairvoyance. Chang’e’s clairvoyance will not become myopia or even completely blind.” 25 The young designer Ji Bo is already He participated for the second time in the meeting and docking mission. When it comes to its products, it compares with pride and enthusiasm.
The orbiter and ascendant complete the rendezvous and docking Image source: China National Space Administration
Speak more reliably
“What we built for this encounter and coupling is not only clairvoyance, but also soft ears. After the upgrade, it is smaller, more powerful, and more reliable,” Sun Wu said.
While ensuring the “homework” of rendezvous and docking measurement, microwave radar has also enhanced the “second job” of bidirectional air-to-air communication between spacecraft. From the “one question and one answer” transmission mode between the radar and the transponder, you upgrade to the “communication dialogue” between the orbiter and the ascendant, which performs the bidirectional transmission of remote control commands and remote measurement parameters.
“Before it was as if a teacher called in class, the radar would send a message and the answering machine would answer ‘a’. Now they not only have to speak on their own, but they are also responsible for the transmission of information between the ascender and the orbiter “. The chief designer of the project of the 25th Microwave Radar Institute He Zhongqin said.
In the previous meeting and docking of “Tianzhou” and “Tiangong”, the microwave radar developed by 25 has achieved a weight reduction of half. This time the Chang’e 5 mission, the microwave radar has been further improved in light weight. “The weight lost by the rendezvous and docking radar is greater than that of lunar soil sampling. Even if the weight is reduced by one gram, it is of great importance for the lunar soil sampling mission,” Sun Wu said excitedly. .
The “perfect performance” of the China Aerospace Science and Industry Fair and docking microwave radar in lunar orbit has witnessed China’s first unmanned rendezvous and docking technology for extraterrestrial objects. Sun Wu said that every step of the microwave radar growth records and every frame of photographs are kept 100% traceable; repeated test iterations and full coverage test verification ensure product features and performance are foolproof. (End up)
