At 7:44 a.m. on January 26, the mainland successfully launched the Land Exploration No. 1 Group 01 A satellite at the Jiuquan Satellite Launch Center with the Long March 4 C carrier rocket. The satellite successfully entered the predetermined orbit and the launch mission was a complete success. The launch of the star arrow are all developed by the Eighth Academy of China Aerospace Science and Technology Corporation, the satellite broke through the strict return to orbit design and control and other key technologies, filled a number of gaps in the field of continental L-band synthetic aperture radar (SAR) satellites, can achieve surface millimeter-level deformation measurement in space thousands of miles away, which is of great significance for the early identification, post-disaster assessment and rescue of geological disasters.
Achieve millimeter-level deformation measurement on the surface
"Geological disasters often cause disruptions to communications and roads. For example, after the eruption of the Tonga volcano, ground communications were completely interrupted, and satellite observation data became the first-hand information of disaster relief work. Chen Junli, chief designer of the land exploration No. 1 01 group of satellites, introduced that geological disasters occur at the same time, often accompanied by precipitation, clouds and other phenomena. The wavelength of the L-band radar of the star is about 23 cm, which has better penetration of clouds and vegetation, adapts to the characteristics of large mountains and wide forest coverage on the mainland, and realizes all-weather, all-day, and high-precision observation, which has a unique advantage in disaster monitoring.
The total area of the SAR antenna carried by the satellite is more than 33 square meters, which is currently the largest SAR satellite in orbit in China, with a ground observation resolution of the meter level and a deformation measurement accuracy of millimeters.
At the same time, multipolarization and full polarization are the main directions of the current development of SAR remote sensing. "To put it simply, unipolarization is a black-and-white image, while a multipolar image contains richer feature information and can colorfully depict our splendid mountains and rivers." Satellite commander-in-chief Li Ruixiang explained. In order to adapt to the different observation needs of geology, land, earthquake, disaster reduction, surveying and mapping, forestry and other industries, the design team has optimized the observation mode of the satellite, and will achieve hybrid mode polarization observation for the first time in China, which will effectively improve the quantitative remote sensing business capabilities such as land use classification.
Large electricity users have a "double package"
Liu Yonghui, commander of the A star power subsystem of the 811 Land Exploration No. 1 Group 01 of the Eighth Academy, introduced that the SAR payload power on the A star of the Land Exploration No. 1 Group 01 is very high. After the satellite has successfully entered the orbit and the SAR payload is turned on, the satellite will begin ground mapping work. In order to ensure mapping coverage, the SAR load will continue to work for about 10 minutes, and the power subsystem needs to meet the transient explosive energy requirements. "The all-day and all-weather working characteristics of this 'big electricity user' also put forward full-time and all-round power demand for the power subsystem."
The SAR payload generates a large pulsating current at the moment of start-up, which will affect the safe and stable power supply operation of the satellite platform. Liu Yonghui said that the developers through careful study of satellite power supply in recent years, compared with domestic and foreign data, innovatively proposed a dual bus power supply distribution mechanism, "SAR payload and platform payload are each powered by an independent bus line, equivalent to providing a 'double package' for satellite power supply." ”
The on-orbit life of the Land Exploration No. 1 Group 01 A star requires a long time, and the discharge depth of the lithium-ion battery pack will inevitably increase, but the deeper the discharge depth, the shorter the service life of the battery. The developers have carried out a large number of ground life tests, solved the problem of long cycle life of lithium-ion batteries under large-rate discharge, and improved reliability through redundant design and power management methods that combine software and hardware.
A small box implements three functions
There is a small box in the body of the Land Exploration I Group 01 A star, which is a differential integrated drive controller. Wang Liang, deputy director of the model assembly of the 149th factory of the Eighth Academy, introduced that this is the first type of satellite complex comprehensive electronic stand-alone machine undertaken by the 149th Factory of the Eighth Academy, which contains 9 functional modules and tens of thousands of stand-alone components, the number of high-density aerospace-grade FPGAs (components) is as high as 12 pieces, and the function integrates the function control of the three subsystems of data transmission antenna, solar array drive mechanism and SAR antenna, realizing "three-in-one".
In order to improve the performance of the product, the star hinge uses titanium alloy material, and the structure has been adjusted adaptively, but this adjustment makes it impossible for the original horizontal way to firmly "lock" their position. In the small structure, two 3 mm positioning pins are also needed, and the product will be scrapped if the hand is unstable. The technician designed a set of assembly limit tooling, which met the assembly accuracy of 0.03 mm and improved the efficiency of the model assembly by 45%.
Source Beijing Daily client | Reporter Liu Suya Correspondent Liu Yanyang Miao Xinpei Fan Wenchao
Edited by Gao Chenchen
Process Editor Liu Weili
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