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Xie Jun, deputy chief designer of the Beidou-3 project of the Fifth Academy of Aerospace Science and Technology Group and chief designer of the satellite. Photo by Li Chuan, a reporter from China Youth Network
Looking up at the starry sky, we can see two "Big Dippers". One with 7 stars, which has existed in the universe for hundreds of millions of years, has been oriented by human beings since ancient times; A star with 30 stars, born from scratch has only 26 years of development, but in the vast space can provide human beings with accurate positioning up to 10 meters.
The former is called "Big Dipper Seven Stars", which is a gift from nature; The latter, called the Beidou-3 Global Satellite Navigation System, is a miracle created by Chinese astronauts.
As the deputy chief designer of the Beidou-3 project of the Fifth Academy of Aerospace Science and Technology Group and the chief chief designer of the satellite, Xie Jun always has many feelings whenever he talks about this.
In 1982, Xie Jun graduated from the National Defense Science and Technology University and was assigned to work at the 504 Institute of the Fifth Academy of China Aerospace Science and Technology Corporation, from where he embarked on the road of spaceflight.
A blueprint drawn to the end. In 1983, Chen Fangyun, an academician of the Chinese Academy of Sciences, put forward the idea of using two geosynchronous orbit satellites for positioning and navigation, that is, the concept of double star positioning, which opened a great journey like the blue wisps of the Yanlu Road.
In 1994, the construction of the Beidou-1 satellite system project was officially launched. In 2000, two Beidou-1 satellites were successfully launched, and China became the third country in the world to have an autonomous satellite navigation system. Beidou-1 system adopts an active positioning system, which can provide Chinese users with positioning, timing and short message communication services, and the system design and construction conforms to China's national conditions at that time, fully embodying the principle of "fast, good and provincial".
In 2004, when the Beidou-2 satellite system project was officially launched, Xie Jun also officially embarked on the post of chief designer of the Beidou-2 navigation satellite. For Xie Jun, this is a new position, but also means a new mission and responsibility.
Compared with Beidou-1, the Beidou-2 system should add a passive positioning system on the basis of being compatible with the technical system of the Beidou-1 system to provide positioning, speed measurement, timing and short message communication services for users in the Asia-Pacific region.
Xie Jun admitted that although the road to research and development is full of difficulties and thorns, he and his team have never given up lightly, always overcome difficulties, and swim against the current.
In Xie Jun's memory, 2007 was an important node for Beidou-2. "In order to ensure the valuable frequency resources applied for by China, we overcame difficulties and successfully launched the first navigation satellite of Beidou-2 on April 14." Xie Jun said.
The victory of the first battle also officially kicked off the prelude to the construction of the Beidou-2 network.
Since then, Beidou-2 has entered the fast lane of networking construction. In 2010, 5 Beidou-2 satellites were successfully launched; In April 2011, the "3GEO+3IGSO" basic system was completed; In December 2012, 14 satellites were officially networked and put into operation, and the Beidou-2 system provided official operation services.
Xie Jun said that by 2019, China has successfully launched 20 Beidou-2 satellites, out of the unique satellite navigation system development path, "this is a unique hybrid constellation system, the accuracy of the Asia-Pacific region has reached the international advanced level." ”
"The advantage of the hybrid constellation system is that it uses high-orbit satellites to provide fixed services to some areas, while medium-orbit satellites provide services to the world." Xie Jun said.
Step by step, step by step.
In 2009, when the construction of Beidou-2 was in full swing, the construction of Beidou-3 system was started. Xie Jun believes that this is a key step for the Beidou system to become world-class and fully comparable to GPS.
"Satellites can not move casually in the sky, a move is equivalent to the coordinate value is changing, the need for precise control, accurate measurement, which involves the key device atomic clock." Xie Jun said that on the Beidou navigation satellite, high-precision atomic clocks are crucial.
Initially, the atomic clocks used on the Beidou navigation satellite relied on imports, which were subject to people and could not fully guarantee the quality, affecting navigation services.
Time accuracy is the life gate of satellite navigation, the more time synchronization between heaven and earth, the smaller the error, the higher the positioning accuracy. After careful consideration, Xie Jun was determined to make the spaceborne atomic clock 100% domestic, take the road of independent research and development, and "must let the important core key technologies firmly grasp in their own hands."
Once the thought is established, no matter how difficult and bitter it is, we must face the difficulties and quickly step up.
The road is obstructed and long, and the line is coming. Xie Jun frankly said that the research and development of spaceborne atomic clocks is very difficult.
The rubidium atomic clock applied to the Beidou navigation satellite generates a fixed frequency by the rubidium atoms in the rubidium bulb being excited by the microwave field, and the frequency emitted enters the absorption bubble after filtering out the unstable noise, and finally generates a photometric signal through the photodetector.
"The high-precision time frequency signal determines the accuracy of the time service between the stars and the earth, and the atomic clock has very high requirements for the space environment." Xie Jun said.
In order to achieve the ideal effect of using the star, Xie Jun led the R & D team to tackle key problems and tests, and they specially designed a temperature-controlled cabin on the whole star to ensure the temperature environment of the atomic clock space with extremely high temperature control accuracy.
Sometimes, for a problem, team members will fight for the red face, even if it is zero, they have to go back to the problem.
It is in such a rigorous and meticulous development process that The rubidium atomic clock independently developed by China is installed on the Beidou navigation satellite.
Xie Jun said that from the "imagination" that still existed on the drawings in 2004 to the high-precision finished products that are now widely used in Beidou navigation satellites, looking back, this road is not easy, but its process is a profound embodiment of the Beidou spirit in the new era.
Independent innovation, open integration, unity of purpose, the pursuit of excellence, this is the beidou spirit in the new era.
The first to win the victory of "frequency", overcome the dilemma of no "clock", eliminate the worry of lack of "core", and crack the difficulty of "standing" cloth. Today, China's Beidou navigation system has reached the international first-class level, with less than 80% of localization on the Beidou-2 satellite and 100% on the Beidou-3 satellite.
Xie Jun said, "We promise to provide navigation better than 10 meters on a global scale, according to the measured results, the horizontal positioning accuracy reaches 1.6 meters, the elevation positioning accuracy reaches 4.4 meters, and the key areas are even more accurate, with a timing accuracy of 10 nanoseconds." ”
In Xie Jun's view, this is the most vivid embodiment of independent innovation and the pursuit of excellence.
June 23 this year is an important day that Xie Jun's aerospace career cannot be forgotten.
Early that morning, Xie Jun had already stood in front of the launch tower of the Xichang Satellite Launch Site and looked at the Long March 3B carrier rocket in front of him, and his mood was both excited and calm.
At 9:43 on this day, the 55th navigation satellite of the Beidou system and the last global networking satellite of Beidou-3 were ignited and launched, soaring into space.
After 27 minutes of satellite launch, the star arrows completed the separation, and the solar wings on both sides of the satellite were smoothly deployed. At that moment, Xie Jun's tense heart finally relaxed.
Xie Jun said that the final star of the Beidou satellite navigation system traveling in space is a milestone that generations of astronauts and Beidou people have finally achieved.
On July 31, the completion and opening ceremony of the Beidou-3 global satellite navigation system was held in the Great Hall of the People. At 10:48, General Secretary Xi Jinping stepped onto the rostrum and announced: "The Beidou-3 global satellite navigation system is officially opened!" The audience erupted in a long and warm applause.
General Secretary Xi Jinping fully affirmed the achievements made in the construction of the Beidou system, especially the Beidou-3 global satellite navigation system. He pointed out that the completion and opening of the Beidou-3 global satellite navigation system fully reflects the political advantages of China's socialist system in concentrating on major events, and is of great significance to enhancing China's comprehensive national strength, promoting China's economic development and improvement of people's livelihood under the normalization of epidemic prevention and control, promoting China's opening up to the outside world under the current international economic situation, further enhancing national self-confidence, and striving to achieve the "two hundred years" goal. Over the past 26 years, all the personnel involved in the development and construction of the Beidou system have faced difficulties, dared to fight hard battles, continued to struggle, carried forward the spirit of "two bombs and one satellite", and cultivated the beidou spirit of the new era. It is necessary to promote the application of the Beidou system, do a good job in ensuring the stable operation of the system and other follow-up work, and make new and greater contributions to promoting China's economic and social development and promoting the construction of a community with a shared future for mankind.
Look up at the starry sky, where there is the dream of Chinese astronauts. General Secretary Xi Jinping once said, "Exploring the vast universe, developing the space industry, and building a space power are the space dreams that we unremittingly pursue." ”
For Xie Jun, the Beidou satellite navigation system is an important embodiment and an important stop for realizing China's space dream. 38 years of aerospace road, 16 years of Beidou Road, Xie Jun sighed the most is the long road is not easy, countless astronauts struggle for respectable, and the indifference and self-confidence of looking back today.
On this road, in the spring, summer, autumn and winter of 26 years, more than 400 units and more than 300,000 scientific researchers worked together to integrate themselves into the huge project of China's Beidou cause, not counting the small self, but achieving the big self.
"Our journey is a sea of stars." Xie Jun said that nowadays, more young Beidou people have become the main force on this journey, they are more energetic, more motivated, and more enthusiastic and hopeful about the dream of a space power.
It is reported that the "Challenge Cup Lecture Hall" is one of the eight competition activities of the 12th "Challenge Cup" China College Students Entrepreneurship Plan Competition, jointly sponsored by the Central Committee of the Communist Youth League, the Ministry of Education, the China Association for Science and Technology, the All-China Federation of Students, the People's Government of Heilongjiang Province, jointly undertaken by China Youth Network and Northeast Forestry University, and supported by China Construction Bank, Alibaba DingTalk and Douyin. Famous teachers lecture hall, big coffee zero distance. The next event will continue to invite industry leaders, well-known people in the society, and well-known scholars in the industry to share their life experience and industry experience through live broadcasting, leading the students of Guangdong University to base themselves on the present and look forward to the future, fully understand the frontiers of science and technology, and grasp the pulse of the times. (China Youth Network reporter Li Chuan)
Source: China Youth Network
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