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01 February 2025, Volume 45 Issue 1 Previous Issue   

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System design and key technologies of No.4 land exploration satellite 01 ZHANG Qingjun, NI Chong, DAI Chao, LIU Liping, TANG Zhihua, SHU Weiping 2025, 45 (1):  1-11.  doi: 10.16708/j.cnki.1000-758X.2025.0001 Abstract ( 362 )   PDF (8217KB) ( 408 )   Save In order to solve the problem of small imaging width and long revisiting time of low orbit SAR,China developed the No.4 land exploration satellite 01,which is a scientific satellite in the medium and long term development plan of national civil space infrastructure (2015-2025),and is the world′s first geosynchronous SAR satellite.Using the advantages of the geosynchronous orbit,the revisiting time of the same place can be reduced from the day level of low orbit satellite to the hour level,and the width can be increased from the hundred-kilometer level of low orbit satellite to the thousand-kilometer level,which can provide strong support for the effective implementation of disaster emergency response.For the new system of geosynchronous SAR microwave imaging,a series of key technologies are developed,such as microwave imaging for geosynchronous SAR,ultra-large power space-borne microwave transmission,ultra-large aperture space-borne antenna,large-flexibility and high-precision attitude stability control,intense pulse high-quality large power supply,integrated efficient thermal management for payload and platform,and integrated satellite-ground high-precision orbit determination.The satellite has the capability of quick revisit,large width,all-day and all-weather observation.The overall design of the satellite is introduced,and the technical innovation is summarized.Through the evaluation of the preliminary test results for the satellite in orbit,the geosynchronous SAR images have clear texture and good quality,which can meet the requirements of disaster prevention and reduction,land resource exploration and other tasks. Related Articles | Metrics

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Design and on-orbit efficiency analysis of onboard GNSS system for LT4A satellite WANG Zhenxing, WANG Yubin, MAO Zhiyi, TIAN Xiaobin, LIU Zhijia, HUANG Yong, SHAO Mingxue 2025, 45 (1):  12-23.  doi: 10.16708/j.cnki.1000-758X.2025.0002 Abstract ( 167 )   PDF (8610KB) ( 131 )   Save The analysis of the onboard high-orbit GNSS navigation receiver system applied on the LuTan-04A (LT4A)， the world′s first Inclined Geosynchronous Orbit (IGSO) Synthetic Aperture Radar (SAR) satellite， is presented. The study investigates the precise orbit determination (POD) performance of the high-orbit GNSS receiver system and reports its engineering application for post-precise orbit determination for the first time. By collecting on-orbit data of BDS and GPS signal anomalies， the quality of onboard observational data and the POD are analyzed and evaluated. Experimental results indicate that the LT4A satellite onboard high-orbit GNSS navigation receiver system can stably capture and track BDS B1I and GPS L1 navigation signals， meeting the requirements for high-orbit real-time positioning， orbit determination， and post-mission precise orbit determination. Utilizing joint orbit determination of onboard BDS+GPS， the in-track accuracy can achieve radial better than 1.87m and three-dimensional better than 3.07m. In response to the characteristics of high-orbit navigation satellite acquisition and the timeliness requirements of applications， the orbit determination system can operate fully automatically throughout the entire process， ensuring the smoothness and continuity of the orbit， and controlling the introduction of high-order Legendre errors. The relevant achievements of this study can be applied to future high-orbit Earth observation satellite missions equipped with GNSS receivers. Related Articles | Metrics

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System design of spaceborne large aperture perimeter truss antenna FENG Tao, ZAHNG Qingjun, LIN Kunyang, WANG Lipeng, ZHANG Qiao, YANG Jungang, XIAO Yong 2025, 45 (1):  24-33.  doi: 10.16708/j.cnki.1000-758X.2025.0003 Abstract ( 177 )   PDF (9223KB) ( 299 )   Save The perimeter truss antenna is the ideal structure of the spaceborne deployable antenna with very large aperture, which is the key payload for high-orbit communication and high-orbit remote sensing satellite applications. The spaceborne perimeter truss antenna is a typical prestressed structure composed of the surrounding truss and cable network system. The accuracy of surface and the fundamental frequency of antenna are the main performance indexes of antennas. On-orbit reliable deployment is the premise of on-orbit application, and reliable deployment is the most important part of antenna design. The influence of ring antenna system parameters on on-orbit performance is analyzed. Based on the analysis of the deployable power system and the transmission power system, the influence of system parameters of the ring antenna on the deployable reliability is expounded. The method of evaluating the on-orbit performance design by structural statics and the deployable reliability by dynamic means are proposed. The design flow of spaceborne large aperture perimeter truss antenna system is defined by strength verification and on-board lock-release design by structural dynamics method, and the optimization strategy of each design parameter is proposed. It provides a reference for technical research and engineering development of the larger aperture spaceborne deployable antenna in the future. Related Articles | Metrics

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Intelligent mission planning method for on-orbit service of high-orbit spacecraft cluster ZHENG Xinyu, CAO Dongdong, TANG Peijia, ZHANG Yi, PENG Shengren, ZHOU Jie, DANG Zhaohui 2025, 45 (1):  34-45.  doi: 10.16708/j.cnki.1000-758X.2025.0004 Abstract ( 90 )   PDF (7312KB) ( 127 )   Save A mission planning model for on-orbit service of high-orbit spacecraft with two optimization objectives, fuel consumption and time consumption, is developed for the high-orbit spacecraft multi-to-multi on-orbit service mission planning. And the Q-learning-based Multi-objective Genetic Algorithm(QMGA) is proposed to solve the model. Firstly, a multi-to-multi objective assignment model based on four-impulse Lambert transfer is established. The velocity impulse consumption and time consumption are taken as the objective functions. By decoupling the problem into the orbit transfer optimization problem and the target assignment optimization problem, the dimension of the optimization variables is reduced, and the calculation process is simplified. Then, combined with Q-learning, the QMGA algorithm is proposed. The Q-learning is used to update the crossover probability and mutation probability of the multi-objective genetic algorithm, which improves the optimization ability of the algorithm. Finally, the QMGA algorithm is adopted to solve the model, and the calculation results are compared with that of the traditional multi-objective genetic algorithm. It is found that the QMGA algorithm can obtain better results and complete multi-to-multi on-orbit service tasks with less fuel consumption in a shorter time. The fuel consumption and the time consumption computed with the QMGA algorithm were 6.2% and 19.7% lower than those computed with MGA algorithm on average, respectively. This proves that the reinforcement learning method can further empower the traditional intelligent optimization method, thereby improving the mission capability of the spacecraft cluster. Related Articles | Metrics

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Detecting satellite unknown fault patterns using digital twin and machine learning SHEN Yinglong, CAI Junliang, LIN Jiawei, YANG Fan 2025, 45 (1):  46-58.  doi: 10.16708/j.cnki.1000-758X.2025.0005 Abstract ( 122 )   PDF (5406KB) ( 137 )   Save Traditional satellite fault diagnosis methods and existing data-driven diagnosis methods both face challenges in identifying unknown faults that differ from known fault types,resulting in lower reliability and safety．To address the problem,a fault diagnosis and unknown fault detection method based on satellite digital twin and machine learning models is proposed．Firstly,various types of fault-simulated data are generated using satellite digital twin,and the fidelity of digital twin data are validated using XGBoost and real satellite fault samples, achieving the diagnosis of known fault types．On this basis,considering that existing methods cannot identify the occurrence of unknown fault types precisely,an out-of-distribution detection model Con-DAGMM is proposed,which is trained on normal data and known fault data to provide warnings for unknown fault．Experiments are conducted using digital twin data and satellite real fault data．The experimental results demonstrate that the proposed method achieves high fault diagnosis accuracy with an average accuracy of 98.8% on the test data．Furthermore,Con-DAGMM achieve high-performance unknown fault detection,outperforming Deep-SVDD and other comparison methods in precision,recall and F1 scores．The results indicate that satellite digital twin can overcome the scarcity of fault samples in satellite historical data,and the out-of-distribution detection approach can be successfully applied to warning of satellite unknown faults,enhancing the satellite's safety and reliability． Related Articles | Metrics

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Improved genetic method for satellite TT&C scheduling under strong resource coupling YIN Xia, HAN Xiaodong, LI Zhaoyu, XU Rui 2025, 45 (1):  59-68.  doi: 10.16708/j.cnki.1000-758X.2025.0006 Abstract ( 39 )   PDF (3665KB) ( 41 )   Save With the development of spacecraft intelligence, an increase in the number of spacecraft and the complexity of missions lead to an increased demand for intelligent spacecraft measurement and control. The coupling degree of satellite TT&C scheduling resources grows, and the solution space dimension expands exponentially. However, existing methods limit the research on resource coupling issues, and the scheduling efficiency can not meet mission requirements. Aiming at the above problems, an improved genetic method for satellite TT&C scheduling under strong resource coupling is proposed. Firstly, the multi-satellite TT&C scheduling problem is modeled, and then the resource coupling in satellite TT&C scheduling problem is analyzed, with the objective function and the hash table type dictionary of conflicting tasks defined. On the basis of genetic algorithm, a two-dimensional chromosome encoding form is designed that combines task sequences and benefits, and a multi-thread generation method is established for initializing the population with advantageous tasks. Multi-thread crossover and mutation operators for sequential decoupling are designed to efficiently process resource coupling information in realtime according to gene order with the assistance of the conflicting-task dictionary. Finally, a scheduling solution of task sequence is obtained through iteration. The results of three simulation experiments demonstrate that this method has good convergence. Compared with the conventional genetic algorithm experiments, the average task benefit of this method increases by 21.31%, and the average runtime decreases by 24.36%. This validates the efficiency of the improved genetic method for satellite TT&C scheduling under strong resource coupling, providing technical support for the operation and management of intelligent spacecraft. Related Articles | Metrics

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Validation method for habitable planets observation variable framework OUYANG Qinglin, LIU Jilin, HUO Zhuoxi, YANG Mengfei 2025, 45 (1):  69-80.  doi: 10.16708/j.cnki.1000-758X.2025.0007 Abstract ( 68 )   PDF (9939KB) ( 59 )   Save The exploration of habitable planets and the detection of potential biosignature are hot topics in the field of exoplanetary science, and represent frontier domains in astronomy and space science. The challenges of current research in this area include how to quantitatively assess planetary habitability and how to identify observational signals representing the presence of life. To address these challenges, an observation variable framework for habitable planets and its elements is introduced. A method is introduced to accurately estimate the habitability of exoplanets with limited understanding. To further validate the completeness of observation variable framework, a specific focus is directed towards investigating the mapping of observational parameters to habitable planets characteristics. By simulating atmospheric spectra of habitable planets, and analyzing the requirement to combine real observational data to verify the accuracy and effectiveness of models, it is underscored that the Earth is an excellent observational template for proxy habitable exoplanets. Additionally, studies which use the Earth as a proxy habitable exoplanet are analyzed by summarizing their observational methods, results, strengths and weaknesses. Building upon this foundation, a mission for spectroscopic observations of the Earth from deep space is proposed. This mission aims to acquire empirical data to validate the completeness of the observation variable framework and the mapping of observational parameters. Such validation serves as essential support for future endeavors in the detection of habitable exoplanets. Related Articles | Metrics

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Variable-emittance space radiator based on near-field thermal radiation XU Deyu, WANG Guoyun, MENG Fankong, ZHAO Junming 2025, 45 (1):  81-87.  doi: 10.16708/j.cnki.1000-758X.2025.0008 Abstract ( 53 )   PDF (5448KB) ( 47 )   Save Aiming at the problem that the radiator of manned space thermal control system is designed according to the maximum heat load and is difficult to adapt to the low temperature condition, a technology of variable-emittance radiator based on near-field thermal radiation regulation is proposed. An effective emittance model of a radiator involved in near-field thermal radiation is developed, and the dependences of near-field radiative heat flux and effective emittance on voltage are solved by using fluctuational electrodynamics and semiconductor carrier transport theory. The coupled heat transfer model of variable-emittance radiator and single-phase fluid loop is established, and the performance of the scheme for temperature control of working medium is simulated and analyzed. The results show that the emittance can be varied up to 0.62 in the voltage range of -5 V to 20 V, and the lowest emittance can be reduced to less than 0.2 under heat preservation condition. Used in conjunction with single-phase fluid loop, the perfluorotriethylamine (PFTA) working medium can be maintained in the normal operating temperature range (-100-50℃) under various internal thermal loads and external thermal environments by tuning the control voltage, thus improving the adaptability of the thermal control system. Although it’s currently difficult and costly to fabricate, with the development of nano-processing technology, the technology has the potential to serve space missions with more complex and variable thermal environments, such as manned deep space exploration. Related Articles | Metrics

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Evaluation of modeled thermospheric density by empirical and physical model YUE Chao, ZHU Jun, LIU Xiaojia, WANG Jun 2025, 45 (1):  88-98.  doi: 10.16708/j.cnki.1000-758X.2025.0009 Abstract ( 40 )   PDF (8491KB) ( 25 )   Save The thermospheric density plays a crucial role in the space environment and is closely related to the atmospheric drag in low-orbit vehicles. Accurately calculating atmospheric density can reduce errors in precise orbit determination and orbital prediction for spacecraft. The thermospheric density was simulated using empirical models (MSIS2.0, DTM2020, JB2008) and physical model TIEGCM2.0 under historical severe, major and minor storms. The simulated density among each model was evaluated by comparing the in-situ satellite observations from CHAMP and GRACE. The simulation results indicate that: The empirical models show better performance than the physical model TIEGCM2.0. MSIS2.0 and JB2008 overestimate the atmospheric density by 28%~44% and 13%~30% compared with satellite observations, respectively. DTM2020 exhibits the smallest differences ranging from-16% to 11%.During geomagnetic quiet or unsettled periods, DTM2020 shows the best performance with a normalized root mean square error of 0.3~0.6. However, JB2008 exhibits the best simulations in geomagnetic active or stormy periods, the correlation coefficient between simulated and observed values is about 0.9. Compared to the TIEGCM with 5° resolution, using 2.5°spatial resolution in TIEGCM can reduce the relative error from 20% to 17%. These results suggest that different models have varying applicability in different space environments. In space engineering applications, considering a combination of multi-model results may improve the accuracy of density and orbit determination. Related Articles | Metrics

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Review of two-phase loop technology for distributed multi-heat sources BI Hanli, JIA Zhichao, LI Guoguang, WU Qi, LIU Chang, ZHANG Hongxing, MIAO Jianyin 2025, 45 (1):  99-112.  doi: 10.16708/j.cnki.1000-758X.2025.0010 Abstract ( 52 )   PDF (11932KB) ( 94 )   Save With the advancement of space technology, the integration level of spacecraft payloads continues to increase. Thermal control systems are required to collect and dissipate heat from distributed and multi-component sources to ensure temperature uniformity among devices. Additionally, as the functionality and performance of spacecraft payloads improve, it is necessary to advance the integrated thermal design of multiple heat payloads and platforms. Therefore, effective methods for heat collection, transfer, and dissipation tailored to distributed, multi-heat-source systems must be developed. This study begins by investigating the current research on three types of single-driven two-phase loops. Single-driven systems face challenges such as low quality limits, restrictions on the number of evaporators, and uneven flow distribution, making them inadequate for addressing the demands of multi-heat-source cooling. Subsequently, the research status of two dual-driven two-phase loop technologies for distributed multi-heat-source systems is reviewed, summarizing their technical advantages. Inspired by the heat transport and dissipation mechanisms in plants, where large trees achieve stable liquid supply and heat dissipation through the combined action of two driving forces, a dual-driven two-phase loop technology based on "osmotic pressure + capillary force" is proposed. Its advantages include enhancing the circulation driving force of the loop heat pipe through osmotic pressure, improving system stability, enabling self-adaptive flow regulation among multiple heat sources, and eliminating low quality limitations. Finally, the study provides a summary and recommendations for future research directions. Related Articles | Metrics

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Brain-inspired navigation method based on place cell and grid cell information fusion LIU Chen, XIONG Zhi, HUA Bing, ZHANG Ling, YANG Chuang, ZOU Weiquan 2025, 45 (1):  113-123.  doi: 10.16708/j.cnki.1000-758X.2025.0011 Abstract ( 29 )   PDF (6505KB) ( 23 )   Save Mammals have the ability to sense exogenous information and self-motion information according to the navigation cells in the brain for self-positioning and navigation,which provides a good biological model for the development of intelligent and adaptive UAV(unmanned aerial vehicle) navigation methods.In this paper,we study the neural mechanism of key navigation cells and the information fusion modelling method,and propose a brain-inspired navigation method based on place cell and grid cell information fusion to address the problems of low real-time loop detection and sparse detection points in the traditional vision-based brain-inspired cognitive map construction method.Firstly,we use continuous attractor neural network and isotropic Gaussian network to model grid cell and position cell respectively,and achieve path integration and position measurement,based on which we propose grid cell zeroing algorithm to improve the efficiency of grid cell wide range calculation.Secondly,the connection weight matrix of the two cell networks is obtained by Hebb-learning rule,which realises the real-time correction process of the position cell to the grid cell path integral.Finally,the 3D position of the UAV is obtained based on the neuron population vector weighted average as well as the grid cell vertex position processing decoding method.The experimental results show that the method proposed in this paper can accurately decode the three-dimensional position of the UAV in a wide range of space,which improves the accuracy compared with the traditional navigation and positioning algorithms,and further expands the application scope of the three-dimensional brain-inspired navigation method for UAVs. Related Articles | Metrics

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Passive intermodulation and its key technology in space microwave communication CHEN Xiang, WANG Xiaoli, SUN Dongquan, SHUANG Longlong, HU Tiancun, CUI Wanzhao, LEI Wang 2025, 45 (1):  124-134.  doi: 10.16708/j.cnki.1000-758X.2025.0012 Abstract ( 35 )   PDF (8820KB) ( 45 )   Save Passive intermodulation (PIM) is a common interference of high power multi-channel microwave communication systems. PIM has serious harmful impact on space microwave communication with shared transceiver antenna, high transmitting power and high receiving sensitivity. PIM will widely exist in the space communication for a long time. Effective solving of PIM problems is the prerequisite for successful development and safe operation in-orbit of space communication payload. The PIM problem under ultra-high transmitting and receiving power ratio conditions will be more complicated in China′s next generation of space communication application, and PIM control has become an important key technology in research and development of space engineering. In this paper, the characteristics and research status of PIM problems are summarized from the aspects of mechanism, analysis and prediction, detection and localization, and suppression technology, and the key technology to solve PIM problem is discussed. Furthermore, the focus of PIM research and the development trend of key technologies are deeply analyzed, combining with the background of space application, which provides some references for the PIM research and technology application of space engineering. Related Articles | Metrics

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Information synchronization method for large scale and high dynamic constellation network KONG Xianglei, SUN Yishu, WU Xueyou, GAO Jianwei, TIAN Zhixin 2025, 45 (1):  135-142.  doi: 10.16708/j.cnki.1000-758X.2025.0013 Abstract ( 27 )   PDF (3371KB) ( 22 )   Save A distributed autonomous mission planning information synchronization method is proposed for large-scale constellation. Due to the periodic movement of satellites, the large-scale constellation is at a high dynamic change. Considering the frequent switching of satellite-ground or inter-satellite task transmission links, the constellation network is split in the discrete time domain. Combining the regularity and unpredictability of constellation network topology, two kinds of constellation information synchronization methods are proposed. When the satellite state is predictable, distributed onboard autonomous collaborative decision-making can be achieved. When the satellite state is unpredictable, a new design method is introduced. The two methods significantly reduce the dependence on ground resources and improve the intelligence and execution ability of autonomous mission planning of constellation. Simulation verifies the effectiveness of the theory. Related Articles | Metrics

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An approach to designing origami flashers with shape accommodation ZHENG Wei, GUO Ce, MA Xiaofei, DONG Ao, ZHANG Zhen 2025, 45 (1):  143-152.  doi: 10.16708/j.cnki.1000-758X.2025.0014 Abstract ( 46 )   PDF (5551KB) ( 66 )   Save Based on the study of geometric relations in the classical origami flashers, an approach to designing origami flashers with shape accommodation is proposed in response to the issues of the classic origami flashers with a single form of folding, and lack of adjustability and adaptability. The methods of establishing mathematical models and theoretical derivation are used to achieve the adjustment of folding height and folding-unfolding curvature of the flasher origami model, and numerical simulations and experiments are also carried out. The results show that this approach not only lowers the flasher model′s folding height, but also modifies the folding-unfolding curvature of the flasher model, which significantly enhances the adaptability and flexibility of origami flashers.The novel crease design approach of origami flashers facilitates their potential applicability in large space engineering applications and deployable mechanisms. Related Articles | Metrics

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Fast vessel detection technology for remote sensing application WANG Haitao, HE Zhijun, ZHOU Tianqi, MA Yue 2025, 45 (1):  153-161.  doi: 10.16708/j.cnki.1000-758X.2025.0015 Abstract ( 28 )   PDF (5459KB) ( 35 )   Save Most existing methods have low recognition accuracy for fine-grained remote sensing vessel detection,and the large computation and storage requirements associated with the commonly used floating-point precision data types make it difficult to meet the needs of model in-orbit deployment due to the limited power of on-board devices.To address these challenges,this paper proposed a fast target detection method for fine-grained remote sensing vessels based on model quantization.Firstly,a fusion intelligence-based detection network was designed to solve the problem of“large intra-class differences and small inter-class differences”,which can effectively improve the accuracy of fine-grained vessel detection and identification.On this basis,a high-precision model quantization method was proposed to optimize the clipping boundary,which could effectively improve the inference speed.Experimental test results show that the proposed method achieves a maximum accuracy improvement of more than 5.9% compared with existing studies,while the quantization method can achieve a maximum performance improvement of 1.2%.It can effectively reduce the calculation load while maintaining a high accuracy,thus can be easily applied to satellite-based computing units. Related Articles | Metrics

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Water extraction from SAR images based on Laplacian edge LI Ke, LI Dacheng, SU Qiaomei, YANG Yi 2025, 45 (1):  162-172.  doi: 10.16708/j.cnki.1000-758X.2025.0016 Abstract ( 25 )   PDF (5526KB) ( 28 )   Save In deep learning water extraction, there exists the problem that convolutional neural network has poor recognition effect on low-level semantic features, such as small lakes and small rivers. To solve this problem, a water extraction method based on Laplace edge enhancement is proposed. Synthetic Aperture Radar (SAR) data set is convolved with the pre-processed SAR data set, using the Laplacian operator to generate the Laplacian edge feature layer. Then the original image is fused with the generated edge feature layer to obtain the enhanced edge SAR data set, which makes the water edge clearer. On this basis, DeeplabV3+ and U-net semantic segmentation models are used for water extraction. The experiment shows that, compared with the unprocessed DeeplabV3+ and U-net models, the two models after Laplace operator processing have improved effect on water extraction in different regions. The U-net model after Laplace operator treatment has the best extraction effect on large water bodies, small lakes and small rivers. Related Articles | Metrics