Recently, China ’s largest and most technologically advanced communications satellite, Practice No. 20, successfully completed all core tests, fully verifying satellite performance and many latest technologies.
The Practice 20 satellite was launched on December 27, 2019 with the Long March 5 Yao-3 carrier rocket, and was in orbital testing after being fixed in geosynchronous orbit on January 5.
Li Feng, Chief Designer of the No. 20 Satellite Practice of the Fifth Academy of Aerospace Science and Technology Group: We have planned the entire whole-star test project to be in orbit, and now the important core load test has been completed, and the results achieved are very encouraging. Fully meet our design expectations.
It is understood that Practice 20 satellite has successfully completed the first in-orbit verification of a number of core key technologies including ultra-high-speed laser communication technology and terahertz technology. Many new products in the field of space technology have also passed the on-orbit test, marking that many key technologies, materials and products in China's aerospace field have reached the international advanced level. In the follow-up, the satellite will carry out long-term orbit work in the mode of providing services while testing.
Practice No. 20: World's on-orbit verification maximum transmission rate
One of the core technologies verified by the practice on the 20th is ultra-high-speed laser communication technology. So what is the concept of "super speed"? What is the significance for communication satellites?
The size of "transmission rate" is the most intuitive manifestation of the capabilities of communication satellites. Before practicing the 20th satellite, China had verified the laser communication technology on the 13th satellite, and the transmission rate was 5Gbps. Practice No. 20 directly doubled this value to 10Gbps, which is currently the highest transmission rate in the world on-track verification.
Zhou Zhicheng, the chief commander of the No. 20 satellite practiced by the Fifth Academy of the Chinese Academy of Engineering Aerospace Science and Technology Group: In the future, you will entertain people, download movies, and the transmission rate will increase a lot, and the human experience will be different. So we have mastered 10 G of laser communication, and in the subsequent application of satellite manufacturing, we will have a lot of solutions available to everyone, including putting laser communication and high throughput in our low-orbit Internet constellation .
In other words, this ultra-high-speed transmission rate will greatly change our lives in the future. In fact, starting from China's first communication satellite "Dongfanghong II", the transmission rate of communication satellites is constantly increasing, and it also provides people with generations of upgraded services. The Practice 20 satellite developed based on the Dongfanghong 5 platform will further widen the frequency band of communication transmission and enhance the user experience, and also lay the foundation for the future development of high-throughput satellites.
Practice No. 20: Comprehensive verification of electric propulsion system
In addition to verifying the transmission rate of communication satellites, as a new technology test satellite, Practice 20 also verified the latest electric propulsion technology. In the future, this technology is expected to be widely used in various spacecraft, greatly improving the operational efficiency of satellites.
For high-orbit communication satellites, the fixed position cannot be changed. Once it deviates from the predetermined position, it cannot provide services in the corresponding area. To maintain this fixed position, a propulsion system is needed to provide power. In the past, this propulsion system generally used chemical fuel as the propellant.
Li Feng, Chief Designer of the No. 20 Satellite Practice of the Fifth Academy of Aerospace Science and Technology Group: We need to carry almost half the weight of the propellant of the satellite to do the east-west (home) guarantee (holding) and the north-south (home) guarantee (holding) This series of work. In this case, the weight of the payload carried by our satellite cannot be increased quickly.
Electric propulsion can solve this problem. The satellite no longer needs to carry a heavy chemical fuel, but carries a special gas-"xenon", which can electrolyze to generate an ion flow and form thrust. This propulsion efficiency has reached about ten times in the past.
Geng Hai, general manager of the 510 Electric Propulsion Division of the Fifth Academy of the Aerospace Science and Technology Group: If such a large satellite needs to be propelled by chemicals, the propellant it carries may be close to three tons, while the propellant we carry may only be 200 Kg, this is an order of magnitude difference.
According to experts, the choice of materials for the electric propulsion system and solving high-voltage power-on problems in space are all world-class difficulties. China has been demonstrating electric propulsion systems since the 1970s, and it has been almost 50 years since today. The implementation of technical verification on the 20th will play an important role in the future development of spacecraft in deep space exploration and other fields.