With the in-depth development of satellite technology in communication, space station, deep space exploration and other fields, air-ground communication is becoming more and more frequent, and it is urgent to increase satellite antennas. Loading a large deployable space antenna on a satellite (or target aircraft) is the only way to achieve this goal.
One of the key materials of deployable space antenna is a kind of warp-knitted metal mesh with light weight, softness, high strength, stable structure, strong wavelength adaptability, high reflectivity and strong deployment reliability. Because the metal wire used to make metal mesh is extremely thin, warp knitting is extremely difficult. Only developed countries such as the United States, Russia and Japan have mastered this technology before, but it is forbidden to export its products.
2065438+On May 2, 20081,China successfully launched the Xingqueqiao, the relay of Chang 'e-4 mission of the lunar exploration project, with the Long March IV C carrier rocket in xichang satellite launch center. Queqiao relay satellite is the first dedicated relay communication satellite outside Earth orbit in human history.
Because the rotation of the moon is the same as that of period of revolution, it only faces the earth, and we can never see the back of the moon directly from the earth. The lander and lunar rover of Chang 'e IV will land on the back of the moon that we can't see. Only when the "Magpie Bridge" is built first will Chang 'e IV not lose contact with us when it reaches the back of the moon. Therefore, the relay star bridge is a communication bridge between the ground and the back of the moon.
Beidou satellite navigation system is a global satellite navigation system independently developed and operated by China. It is called the world's four major satellite navigation systems, together with the global positioning system of the United States, GLONASS of Russia and Galileo of Europe. On June 23, 2020, the last global networking satellite of Beidou-3 was launched, marking the full completion of China Beidou satellite navigation system. Dozens of navigation satellites in space, like chess pieces, are accurately distributed in different orbits of the earth and revolve around the earth day and night, providing high-quality communication and positioning services for users in China and other countries.
Space communication satellites such as Queqiao relay satellite and Beidou satellite all have the same key component-deployable mesh antenna reflector, which plays the role of reflecting electromagnetic signals at a long distance. The reflector of mesh deployable antenna is the most important structure of large and super-large deployable space antennas. Like an umbrella, it is put away when it is launched and will be opened in time when it enters space.
Among them, metal mesh is the key component of space antenna to reflect electromagnetic waves and the basic material of space-borne mesh antenna. However, for a long time, China's satellite antenna metal mesh mainly relies on imports. How can we break through technical barriers and stop being subject to others?
Nowadays, in the laboratory of the Engineering Research Center of the Ministry of Education of Industrial Textiles of Donghua University, there is a special "umbrella": it does not shelter from rain or sun, and the special umbrella ribs support a thin layer of yellow metal mesh.
In fact, this special "protective umbrella" has played a vital role in China's Beidou navigation satellite, mobile communication satellite and other series of space satellites. It not only created the history of independent research and development of China satellite metal mesh antenna, but also played a milestone role in the localization of key products of flexible antenna, laying a solid foundation for the on-orbit application of domestic metal mesh.
Since 2008, Professor Chen Nanliang of Donghua University and his team have joined hands with relevant scientific research institutes to embark on a road of tackling key problems that "the national space mission must be realized". Chen Nanliang's team has been adhering to the scientific belief of "strong textile intelligence", constantly breaking through technical barriers and truly realizing localization.
In the past, most of the antennas were made of traditional metal materials such as aluminum alloy, which had high density and hardness, and could not expand and contract freely in space. So, is there a material that can make the satellite antenna light, strong and stable?
In repeated experiments, the team found that the gold-plated molybdenum wire material has the characteristics of high strength, low thermal expansion coefficient and high reflectivity, and is an excellent choice for manufacturing the reflective surface of the space deployable mesh antenna.
However, it is not easy to make metal mesh with gold-plated molybdenum wire, because the metal mesh should be strong enough to withstand the external force of launching flight, and soft enough to be woven in space. For the team, warp knitting technology is essential if they want to obtain a metal mesh with both rigidity and flexibility.
Textile is usually the intersection of warp and weft (the structure of shirt fabric), while warp knitting, like knitting a sweater, bends the yarns into loops and overlaps them to form a fabric. In the production of mesh fabric, warp knitting technology is superior to other production technologies: the produced mesh structure is more malleable, more stable and firm, and more suitable for folding and unfolding the reflector, and the satellite "survives" in the harsh space environment.
Due to the particularity of gold-plated molybdenum wire raw materials, there is no special production process and equipment in the market. As a result, Chen Nanliang plunged into Changzhou, one of the four warp knitting bases in China, with the backbone of the team, and "cats" in the factory together with enterprise technicians, innovating production methods and transforming process equipment.
There is never a shortcut to independent innovation. In the words of the research group, they have been "crossing the river by feeling the stones" and often find that "experimental failure is nothing more than a normal phenomenon". Once, because the molybdenum wire was too thin to be detected by the naked eye, the workers accidentally broke all the wires during operation. This can be anxious for the entire research team. "Bite your teeth, maybe you will succeed next time", so all the staff went into battle and stayed up all night. The first batch of samples were finally repaired in time.
After persistent scientific research, the team adopted the technology of ultra-fine wire twisting and warp knitting, realized the technical breakthrough of twisting and twisting of ultra-fine gold-plated molybdenum fiber (only 1/4 fine wool), designed and manufactured special doubling, warping and warp knitting equipment, and designed a whole set of production technology.
This series of technical and technological breakthroughs not only successfully produced a "rigid and flexible" satellite antenna metal mesh, but also reduced the weight of this "big umbrella" by more than 90%. Finally, the project team broke through the key technology and industrialization of warp knitting of metal mesh material for large deployable flexible antenna of high performance satellite.
"Spaceborne antenna metal mesh" has played a vital role in many series of satellites such as Beidou navigation satellite and mobile communication satellite in China. This achievement not only created the history of China satellite adopting self-developed metal mesh antenna, but also laid a milestone foundation for the localization process of key products of flexible antenna and its smooth application in orbit. It not only greatly improves the communication capability of our satellites, but also makes China the second country in the world to develop a space-borne antenna with a diameter of 10 meter or more after the United States.
In the future, the Engineering Research Center of Donghua University's Industrial Textiles Ministry of Education will continue to devote itself to the research and development of high-performance industrial textiles. While perfecting and improving the application products such as Tiangong series semi-rigid solar substrate and spaceborne deployable antenna metal mesh, we will actively carry out research on key aerospace materials such as stratospheric airship, deployable capsule and space landing airbag, and will continue to forge ahead with the belief of "textile power".
This article was originally published in the ninth issue of Science Illustrated in 2020, and was supported by the Science and Technology Innovation Action Plan of Shanghai Science and Technology Commission 20 19. Project name: "Based on Science and Technology Innovation Center, Spreading Frontier Science and Technology-Creating Shanghai Popular Science Achievement Media Column"; Project number: 19DZ2332600.