Editor’s note: When launched on wechat between Sept 25 and 28, users can enjoy panoramic views of the country taken from space by China’s new-generation geostationary orbiting weather satellite, Fengyun-4. This is the first time in six years that the wechat launch page has been changed. The background of the launch page has been changed from an aerial view of the African continent to an aerial view of our motherland. Behind this is 15 years of persistence and dedication of researchers. Scientists say it’s worth it to bite off a tough nut that both the U.S. and Europe have retreated from.
On the right is a launch page made from photos taken by Fengyun iv
Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai interferometric atmospheric vertical detector team sent samples to the institute
Space, fresh from the burn down to the shadow of the sun, at the end of last year launching from the situation of geostationary orbit meteorological satellite, 4 two complete generation instrument – a new generation of technology leapfrogging scanning imaging radiometer, interferometric atmospheric vertical detector, withstood the huge temperature changing in space test, flowing underground mass remote sensing data.
On the ground, their creators, scientists from the Feng Iv payload team at the Shanghai Institute of Technical Physics, Chinese Academy of Sciences, breathed a sigh of relief. 15 years of persistence and dedication. Hua Jianwen, the chief scientist, said that it was worth it to tackle the hard bone that had made the United States and Europe retreat from difficulties in this life.
36,000 kilometers above the earth in the geostationary orbit, the new “Chinese eyes” are sending back a lot of “Chinese data”. Some of these data are eagerly awaited by the international meteorological community, and none of the satellites currently in orbit, except China’s Fengyun-4 weather satellite, can provide them.
We insist when others give up
“No radiometer, no wind four; Without the detector, it would not be the Fourth wind of China.” Ding Lei, deputy director of the Shanghai Institute of Science and Technology and chief designer of the detector, refers to the boldness of Kuang Dingbo, an academician of the Chinese Academy of Sciences, who supported the development of the interferometric atmospheric vertical detector more than a decade ago.
Since the launch of fengyun-2 in 1997, planning has begun for the next generation of fengyun-2 satellites. Kuang Dingbo proposed that the interferometric atmospheric vertical detector should be developed. This detector, which uses the principle of Fourier transform, can do “super CT” for the atmosphere — slice the atmosphere from the ground up into thousands of layers, and measure the temperature and humidity of each layer, so as to serve for disaster weather monitoring and atmospheric chemical composition detection.
“For example, cold air from the Tibetan Plateau sinks and flows east, lifting the hot air there. This process has been largely theorized and never observed.” The data from the probe may provide the first real “look” at the process, Ding said.
This is a revolution of infrared spectroscopy technology in remote sensing field. Earlier, the United States and Europe were working in this direction, but by 2006, because of the technical difficulties and costs, the United States gave up, and Europe has drastically adjusted the plan.
Does China want to continue?
Hua Jianwen, who came back to China in 2001, led his team to call up the infrared interference signal at the end of 2005, and the prototype was initially successful. “Although the bone is difficult to gnawing, sending the instrument to the sky is the first step towards success,” Kuang said.
It is recognized by international peers that the “slice number” of detector reaches 1000, which is the watershed for measuring the quality of detection. “Not only did we do it, but we set our sights on the 1500 floor, which is almost a dream number.” Ding Lei says, since want to chew hard bone, pick the most difficult attempt.
Now, while The Chinese probe is providing exclusive global data, the American team has yet to reassemble and the European instrument will not be launched until 2022.
“We insist when others quit. If you succeed, you lead the world.” Hua jianwen said that in the past, China asked foreign satellites for data, but now the international meteorological community urgently needs Chinese satellite data.
A lifetime for a star, I will
The number of spectral channels expanded from 5 to 14; The spatial resolution of visible light increased from 1.25 km to 500 meters; The imaging time of the earth’s full disk has been improved from 30 minutes to 15 minutes, and can be further improved to less than 5 minutes in the future… Compared with the instrument on fengyun-2, the scanning radiometer on fengyun-4 achieved a technological leap across generations.
How accurately can the scanning mechanism of the imaging radiometer aim at the shooting point? The chief designer, Wang Ganchuan, said that by placing a row of 10,000 needles with only 0.04 square millimeters of pinholes at the distance of a football field on one side, and using a mirror of the scanning mechanism to reflect laser light through the holes on the other side, 9,997 needles can accurately pass through.
In order to evaluate the accuracy of the scanning mirror, Wang Ganchuan has been thinking about it for 12 years. If you can’t test and calibrate, how do you know if the instrument is up to standard? One day in 2014, he came across information about a device that could measure within a tenth of a second. But only one or two domestic units may have this technology, but whether the accuracy can meet the testing needs of the scanning mirror is unknown.
He spent more than a year, back and forth to Beijing, Xi ‘an and other places, constantly communicate with relevant researchers, facilitate the improvement of the equipment, and finally made the scanning mirror dynamic accuracy detection instrument.
Faced with so many unchallenged technical difficulties, the long research and development cycle tests the qualitative of researchers. The research and development cycle of general satellites is 4-6 years, but the research and development cycle of meteorological satellites with high precision and quantitative application characteristics is more than 10 years. A generation of meteorological satellites often want to launch several successively, from the first to the last sky, there are several years, plus in orbit operation of maintenance tasks — this life is really only enough to do this batch of stars.
The project was difficult to move forward, and many of the young people on the team came and went, but still stuck with it. Detector team “veteran” one of Wang Zhanhu moved the idea of leaving, and even to apply for a new job, can think of a dream to tune out the first beam of infrared interference signal, the last moment or left. “Last year when the probe went up in the wind, I felt like I had a new relative in the sky.” He said, “I will live for one star all my life.”
Satellite payload takes private companies to the skies
How well spacecraft can do depends on a country’s industrial base. Even if scientists can design the latest payloads, it’s still pie in the sky if the key components can’t be processed by manufacturers.
The team struggled from the start. According to the design requirements, some lasers and spectrometers were needed in the load. At that time, these devices could not be found in China. They sent more than 100 emails to look for these products worldwide. However, when the foreign side learned about the specific parameters, they rejected the requirements of technical cooperation, or because there is no “sales license”, do not want to sell the product.
Designed and developed by themselves, they began to look for cooperative enterprises in China. There is a material called aluminum-based silicon carbide, as light as aluminum, thermal expansion and contraction deformation is small, thermal conductivity is also particularly good, but 3 times harder than aluminum, very suitable for fengyun4 this complex thermal environment, the degree of lightweight requirements of the satellite load structure. But due to processing difficulties, has not been used.
In 2009, domestic enterprises were finally able to process the material. They immediately found the company and worked with it to improve the technology and finally developed the first set of aluminum-based silicon carbide scanning mechanism frame in China, which was successfully applied in two payloads. Now, the industry has faced a wide range of domestic applications.
The code plate in the induction synchro is the key part, and the scanner and detector can realize the high-precision “point to hit”, which plays a decisive role. There are only one or two companies in the world that can make products that meet the requirements of space. Once they heard that the product has such high precision, they all refused.
Finally, the researchers found a private enterprise in Changshu. The owner of this factory, retired before the kunming machinery factory chief engineer, has participated in the national organization of related product research and development. However, the private company has little experience in developing highly reliable aerospace products. The researchers solved the reliability problem almost hand in hand, and finally developed the highest precision induction synchronizer in China to meet the aerospace requirements.
Carbon fiber braided materials, special testing equipment, long-life high-performance grease… In 15 years, feng4 team has driven many private enterprises to upgrade their technology through the project. “Although private companies don’t have a management system for space products, quality tracking is very tiring.” “But seeing your technology and business lead to change in these industries is as fulfilling and satisfying as putting a satellite into space,” Mr. Hua said.
Source: Wen Hui Po