On January 26, the land Exploration Group 01 A satellite, developed by the eighth Academy of China Aerospace Science and Technology Corporation, was successfully launched from jiuquan Satellite Launch Center.After being in orbit, landprobe I 01 GROUP A will provide strong space technology support for geological disasters, land survey, earthquake assessment, disaster prevention and mitigation, basic mapping, forestry survey and other fields.The satellite has made breakthroughs in key technologies such as strict regression orbit design and control, and filled in many gaps in China’s L-band synthetic aperture radar (SAR) satellite field. It can achieve millimeter-scale surface deformation measurement from thousands of miles away in space, which is of great significance to the early identification, post-disaster assessment and rescue of geological hazards.Geological disasters are a common problem facing mankind. There are many kinds of geological disasters in China. Every year, tens of billions of people’s lives and property losses are caused by landslides, mud-rock flows, earthquakes and ground collapse.But at the same time, the monitoring of geological disasters is a common problem faced by scientists all over the world.”Geological disasters tend to disrupt communications, roads.For example, after the tonga volcano erupted, all communications from the ground were cut off, and satellite observations became the first source of information for disaster relief efforts.””Geological disasters are often accompanied by precipitation, clouds and other phenomena,” said Chen Junli, chief designer of the SATELLITE.Radar satellites have unique advantages in disaster monitoring because they can penetrate clouds and surface vegetation to achieve all-weather, all-weather and high-precision observation.”The landspass-1 used the L-band synthetic aperture radar differential interference detection system.”The L-band radar has a wavelength of about 23 centimeters, which has better penetration of vegetation and is adapted to China’s mountainous areas and wide forest coverage.”Chen Junli introduction.”Differential interference is actually the application of wave interference principle in physics. Remote sensing data of the same area is obtained by satellite radar, and then evolution and calculation are carried out to form differential interference map. After comparison, the deformation of the surface can be obtained with the accuracy of millimeter-level.It can provide important technical support for geologists to carry out early identification of geological hazards, earthquake monitoring, volcanic movement, tectonic movement, urban subsidence and other research.”It is reported that the SAR antenna carried by the satellite covers an area of 33 square meters, making it the largest SAR satellite in orbit in Korea.The resolution of ground observation is up to meter level and the accuracy of deformation measurement is up to millimeter level.Accurate control: the in-orbit non-yawing satellite keeps circling the earth orbit, but the principle of differential interference requires that the satellite must be able to observe in the same position after multiple flights, which brings unprecedented challenges to the orbit design and control of the satellite.”The satellite in space flight, in fact, also has a ‘lane’, but affected by various factors, the flight path will be up and down the left and right changes, to visualize it, will form a similar ‘pipe’ model.Strict regression orbit design and control is to ensure that the satellite as much as possible in the flight of the tube, not yawing.”Satellite deputy chief designer Wang Wenyan explained.Based on the precise high-order gravity field model of the Earth, the research team proposed a new method of strict regression orbit design, and innovatively adopted the independent determination and control technology of three-dimensional space, so that the satellite regression accuracy can reach sub-meter level.During repeated observation, the control radius of the satellite orbit pipe can be precisely controlled within 350 meters, reaching the international advanced level.Multipolarization: Multi-polarization and full polarization are the main development directions of SAR remote sensing at present.”To put it simply, single-polarization is a black and white image, while multi-polarization image contains richer ground object information, which can depict our beautiful mountains and rivers in a colorful way.”Satellite commander Li Ruixiang explained.In order to solve the problems of limited full-polarization viewing range and limited application of traditional SAR satellites, the satellite development team innovatively proposed a series of new imaging technologies such as hybrid polarization satellite-borne SAR beam shaping, which will increase the viewing range of full-polarization mode by two times and greatly improve satellite observation performance.”In order to adapt to the different observation needs of geology, land, earthquake, disaster reduction, surveying and mapping, forestry and other industries, we have optimized the observation mode of the satellite, and will realize the mixed mode polarization observation for the first time in China, which is conducive to improving the quantitative remote sensing service capabilities such as land use classification.”Li Ruixiang introduced.