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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 Chinese Space Science and Technology    2025, 45 (1): 1-11.   DOI: 10.16708/j.cnki.1000-758X.2025.0001 Abstract （923）      PDF（pc） （8217KB）（867）       Knowledge map    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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Analysis and key design of lunar far-side robotic sampling and return misson SHENG Ruiqing, MENG Zhanfeng, ZHAO Yang, TAN Zhiyun, ZHANG Hong, HUANG Hao, ZHANG Wu Chinese Space Science and Technology    2024, 44 (5): 1-14.   DOI: 10.16708/j.cnki.1000-758X.2024.0069 Abstract （786）      PDF（pc） （17095KB）（613）       Knowledge map    The Chang′e-6 lunar probe is designed to achieve the first robotic sampling and return mission from the far side of the Moon.The lunar far side has rugged terrain overall and lacks flat areas suitable for sampling.Two areas in Apollo basin within south pole Atiken basin （SPA）are selected as primary and backup targeted landing sites，the safety and reliability of landing，lift-off and surface operation process are ensured.In order to achieve new mission objectives within the establis hed technical configuration，an optimal system design solution is put forward to reduce system changes.The risks associated with alterations of technical status are avoided.Through comparative analysis，a retrograde orbit around the Moon is selected，ensuring minimal system modifications and optimal system design.In consideration of the reduced and discontinuous duration of relay telemetry and control on the far side of the Moon for Chang′e-6，a phased，highly autonomous，and cooperative relay-assisted lunar surface operation timeline design is proposed to ensure the implementation during landing，lift-off and surface operation process.For payload carried by Chang′e-6，a system design is proposed by using data processing units as the central exchange hub to ensure electrical interface safety isolation；customized detection modes are also developed for different payloads to maximize detection benefits without affecting the completion of the main mission.These methods are applied in the Chang′e-6 mission，ensuring the success of the world′s first robotic sampling and return mission from the far side of the Moon，valuable reference and experience are provided for follow-up lunar exploration and deep space exploration missions. Related Articles | Metrics

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System design and validation of Queqiao-2 lunar relay communication satellite ZHANG Lihua, XIONG Liang, SUN Ji, CHEN Luojing, XIAO Chuan, ZHOU Wenyan, WANG Yong, LIU Wangwang, GUAN Yifeng, CHEN Tao, YU Xiaochuan, XU Jin, CHEN Guohui, CAO Xiaoping Chinese Space Science and Technology    2024, 44 (5): 23-39.   DOI: 10.16708/j.cnki.1000-758X.2024.0071 Abstract （749）      PDF（pc） （8335KB）（798）       Knowledge map    In order to provide relay communication supports for future Chinese lunar exploration program，Queqiao-2 relay communication satellite was developed.Queqiao-2 can perform scientific observations with three kinds of scientific instruments on board.The system design of Queqiao-2，including mission orbit and transfer orbit design，configuration and layout design，housekeeping and information flow design，power supply and distribution design，GNC and propulsion system design，communication links design，etc.，was accomplished through comprehensive tradeoff and evaluation on technical maturity，availability，schedule，cost，and so on.With a view to reducing development risk，both the platform and relay communication payloads were developed based on significant heritage from previous Queqiao relay satellite and other relevant spacecraft.Queqiao-2 features flexible system architecture to support multiple frequencies，modulations，data rates and software reconfigurations to meet new user requirements.Subsequent to a successful launch on March 20，2024，by means of 5 orbit maneuvers，Queqiao-2 was inserted into a highly elliptical frozen mission orbit around the moon with a 24h period on schedule.Following on-orbit tests and calibrations，Queqiao-2 has possessed the capacity to provide reliable relay communication services to multiple lunar exploration missions，as well as the capacity to perform scientific observations.Under the support of Queqiao-2，Chang′e-6 achieved its ambitious mission goal to collect  and return samples from the moon′s mysterious far side.In the meanwhile，Queqiao-2 has also paved the way for the following Chinese lunar exploration missions including Chang′e-7 and Chang′e-8.The design life time of Queqiao-2 is more than 8 years.Benefit from flexibility and extensibility of relay communication system design，it is convenient to provide relay communication services for future lunar exploration missions of both China and other countries.In addition，innovative scientific observations would be performed during the period that no relay communication task is arranged.The system design of Queqiao-2 reflects the development philosophy of technical innovations and inheritance integration.Based on highly flexible and extensible system architecture，multiple and concurrent relay communication mission requirements can be met.It can provide strong supports for future lunar exploration missions.Successful launching，orbit entering and on-orbit tests of Queqiao-2 verified the correct design principle and versatility.By means of Queqiao-2，more innovative scientific outcomes are anticipated and lunar exploration activities can be facilitated. Related Articles | Metrics

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Multi-impulse pursuit-evasion game in GEO based on improved dung beetle optimization GUO Yanning, LI Gaojian, YU Yongbin Chinese Space Science and Technology    2024, 44 (4): 1-10.   DOI: 10.16708/j.cnki.1000-758X.2024.0052 Abstract （637）      PDF（pc） （4364KB）（580）       Knowledge map    This paper investigates the pursuit-evasion game of GEO with J2 perturbation and impulsive thrust considering perception delay.An optimization model of orbital pursuit strategy is established，considering fuel consumption，single impulse velocity increment，impulse interval time，mission duration，impulse quantity，and terminal distance.The design variables include the number of impulses，the sequence of maneuver moments，and the sequence of impulse increments.The pursuing spacecraft pursues the target spacecraft through multiple impulses.To enhance problem-solving efficiency，an improved Bernoulli dung beetle optimization algorithm（IBDBO）utilizing Bernoulli chaotic mapping and optimal value guidance is proposed.Additionally，Lambert maneuver correction is introduced to address terminal constraint satisfaction issues.The comparison experiments with other intelligent algorithms verify the superiority of this algorithm in terms of convergence speed，convergence stability and optimization efficiency.Furthermore，simulations in real scenarios with perceptual delay demonstrate the effectiveness of this algorithm for planning pursuit strategies.Finally，the causal relation between terminal distance of both sides in the game and the target spacecraft′s maneuvering capabilities，perception delay time is explored. Related Articles | Metrics

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Matching design of trajectory with Chang′e-6 mission and flighting pratice of Queqiao-2 satellite ZHOU Wenyan, GAO Boyu, DONG Tianshan, LIU Decheng, SUN Ji, ZHANG Lihua Chinese Space Science and Technology    2024, 44 (6): 16-22.   DOI: 10.16708/j.cnki.1000-758X.2024.0087 Abstract （625）      PDF（pc） （2897KB）（337）       Knowledge map    Queqiao-2 provides relay services in its overall life cycle for Chang′e-6, Chang′e-7, Chang′e-8, and Chang′e-4 missions, as well as lunar exploration missions from international cooperation. To meet the different relay needs of multiple launch windows and different flight phases of Chang′e-6 mission, the trajectory design method and process of the Queqiao-2 relay satellite to service the Chang′e-6 mission are introduced from the perspective of mission analysis. The adoption of a lunar elliptical sun-synchronous frozen orbit satisfies the requirements for communication range, coverage, launch windows, and orbital phase for the Chang′e-6 mission. Then the trajectory scheme and the control strategy adopted on each flight phase are optimized with minimum fuel constraint. A four-impulse joint optimization trajectory control strategy is employed to significantly alter the orbital ascending node, inclination and argument of perilune with few velocity increments. Finally, the status of the in-orbit flight and relay support for Chang′e-6 mission are shown respectively. For the first time internationally, Queqiao-2 has achieved a significant change of right ascension of the ascending node in lunar orbit by using a lunar low energy capture orbit, and close range and long arc relay of target on the far side of the moon by using the lunar large elliptical sun-synchronous and frozen orbit. The result shows that the in-orbit flight of Queqiao-2 is consistent with that of the design, which ensures the successful implementation of the Chang′e-6 lunar far-side sampling and return mission. The design method can provide a reference for the orbit design of deep space exploration missions. Related Articles | Metrics

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Chang′e-6 mission planning leveraging geometry approach MENG Zhanfeng, GAO Shan, ZHAO Qiao, ZHANG Xiangyu Chinese Space Science and Technology    2024, 44 (6): 1-15.   DOI: 10.16708/j.cnki.1000-758X.2024.0086 Abstract （601）      PDF（pc） （15016KB）（522）       Knowledge map    The Chang′e-6 mission is the first lunar far-side sampling return mission in the world. The mission planning is an important assignment in the spacecraft system design. Mission planning problem is conventionally converted to the numerical constraints optimization problem in the traditional method. However, by using this method, the constraints could not be satisfied directly, and at the same time, the design variables dimension increased, the computing efficiency decreased, and the physical meaning was not apparent. A new mission planning approach using the mission geometry is proposed in this paper. According to the new approach, the periapsis constraints of the Earth-to-Moon and Moon-to-Earth transfer trajectories, the relative geometry constraints on sampling point and lunar orbit plane, and the geometry relationship of the Sun-Earth-Moon are fully considered. The new approach reduced the design variables dimension, improved the computing efficiency. In addition, it also has the advantage of intuitive spatial geometric interpretation, and the result can be verified easily. The new approach has been applied to mission planning and trajectory design in the Chang′e-5 and Chang′e-6 missions successfully, and will be adopted in the future lunar exploration mission. Related Articles | Metrics

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Research on lunar base based on cave LI Linling, LIU Jingang, HOU Yukui, LIU Wei, LI Mingfu, YIN Shuohui, WANG Lei, XU Mengchuan, Peng Jing, SUN Zezhou Chinese Space Science and Technology    2025, 45 (3): 9-18.   DOI: 10.16708/j.cnki.1000.758X.2025.0034 Abstract （559）      PDF（pc） （7961KB）（515）       Knowledge map    The relevant policies， plans and specific projects of cave lunar bases at home and abroad were investigated systematically， with a focus on the comparative analysis of the existing gaps in research achievements. Based on the image information of lunar exploration at home and abroad and the research results of cave lunar base concept， the feasibility concept of cave lunar construction has been sorted out. Based on the unique advantages of the cave (such as suitable temperature， low radiation， less lunar dust， etc.) and the objective conditions of the difficulty of building a lunar base， a qualitative analysis was conducted on various concepts of cavebased lunar bases. Each type of lunar base configuration shows unique advantages： the cavebased lunar base based on the transformation of craters makes full use of the natural terrain on the lunar surface， combines the natural structural characteristics and artificial transformation requirements， and has significant advantages insitu resource utilization. Whether it is an unmanned or manned cave lunar base， it will go through four key strategic stages： lunar exploration， lunar address selection， lunar base construction and lunar base application. Although a large number of lunar images have been obtained through the launched lunar orbit probe， lunar surface probe and other exploration means， the current lunar surface exploration capabilities still need to be further improved to provide stronger support for the "site selection" work of the construction of the cave lunar base. At the same time， it is urgent to accelerate the development of key equipment for the construction of lunar bases as soon as possible， provide implementation tools for the construction of unmanned lunar bases， implement the "foundation" task of the cave lunar base， and realize the strategic goal of "cave utilization" of the cave lunar base as soon as possible. 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 Chinese Space Science and Technology    2025, 45 (1): 24-33.   DOI: 10.16708/j.cnki.1000-758X.2025.0003 Abstract （508）      PDF（pc） （9223KB）（563）       Knowledge map    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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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 Chinese Space Science and Technology    2025, 45 (1): 12-23.   DOI: 10.16708/j.cnki.1000-758X.2025.0002 Abstract （490）      PDF（pc） （8610KB）（304）       Knowledge map    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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A review on recent development of space solar power HOU Xinbin , , MANKINS John, SHINOHARA Naoki , CHOI Joon-Min, SOLTAU Martin Chinese Space Science and Technology    2024, 44 (6): 33-51.   DOI: 10.16708/j.cnki.1000-758X.2024.0089 Abstract （471）      PDF（pc） （16542KB）（446）       Knowledge map    Space solar power (SSP) system, a major type of space-based power-generating equipment, is an important infrastructure providing massive, continuous, and stable green electricity by utilizing solar energy in space. Many countries and organizations consider SSP to be one of the most promising clean energy sources. The historical activities of SSP in the world are summarized. This review focuses on the significant development of SSP during the last 10 years, which is the most important period for SSP. The latest international SSP development programmes in the United States, ESA, Japan, China, UK and Korea are presented. Some significant solar power satellite(SPS) concepts proposed in the decade, including typical SPS-ALPHA, MR-SPS, CASSIOPeiA SPS, et al., are introduced. The technical and non-technical challenges are also listed and several important in-space demonstration missions in recent years and in the near future are introduced. The conclusion is that the next 5 to 10 years will be an important period for rapidly developing the key technologies and conducting on-orbit demonstration and application. Controlling the mutual position relationship between the solar array and the transmitting antenna becomes a core issue to be considered in the innovative design of the SPS. Wireless power transmission technologies would be the demonstration focus for the first step. It is expected that the first commercial SPS would be constructed as early as 2040. Related Articles | Metrics

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Research status and prospect of space thermophotovoltaic power generation technology QIU Jiawen, TIAN Dai, HAN Chengzhi, ZHANG Ran, SU Sheng, MA bin, TANG Liangliang, SHAO Jianxiong, ZHU Anwen Chinese Space Science and Technology    2024, 44 (5): 40-56.   DOI: 10.16708/j.cnki.1000-758X.2024.0072 Abstract （465）      PDF（pc） （4668KB）（398）       Knowledge map    Space radioisotope power is a space power device that converts nuclear decay thermal energy into electrical energy through thermoelectric conversion technology，and is widely used in deep space exploration missions.Space isotope power commonly uses plutonium 238 as nuclear sources.The preparation and production of plutonium 238 are difficult and expensive，resulting in worldwide limited production capacity.Meanwhile，long-term deep space exploration missions propose high requirements for the lifespan of isotopic power.Space thermal photovoltaic radioisotope power with high thermoelectric conversion efficiency and long lifespan has become the preferred technical route for deep space exploration missions.NASA has demonstrated a RTPV prototype with a conversion efficiency greater than 20%.In recent years，near-field thermal photovoltaic and spectral-regulation thermal photovoltaic technology have become the hotspot.Significant progress has also been made in the theoretical research and technical verification of critical devices such as emitters，optical filters，and photovoltaic cells.In this paper，the research progress of RTPV system designs and relevant key devices is reviewed.Based on the system level requirements，the development status of each device is stuaied and the future trend is suggested.This paper provides a reference for promoting the engineering development of thermophotovoltaic radioisotope power supply system in the future. Related Articles | Metrics

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Construction scheme of cylindrical modular space solar power station ZHANG Shuning, YANG Jingyu, WANG Ershen, LI Zisen, XU Song, HE Jingjie, LI Chen Chinese Space Science and Technology    2024, 44 (6): 52-63.   DOI: 10.16708/j.cnki.1000-758X.2024.0090 Abstract （438）      PDF（pc） （6857KB）（295）       Knowledge map    Most of the existing space solar power station (SSPS) schemes are conceptual designs with poor comprehensive performance. So a highly feasible engineering design scheme of SSPS via cylindrical modular concentrator array (SSPS-CMCA) is proposed. Firstly, the SSPS schemes proposed by scholars and organizations from various countries are analyzed. The scheme combination table is listed from the perspective of structure, control, shape, etc. A set of scheme standards for the design of SSPS is summarized. Then the SSPS-CMCA scheme is proposed according to this standard. The structural design of the scheme is described in detail, and the performance of each aspect and the system parameters of 1GW model are analyzed. Finally, the construction scheme of the whole process from ground experiment to space assembly and operation is proposed.  Related Articles | Metrics

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Review on spacecraft autonomous decision-making and planning for orbital threat avoidance GAO Wanying, WU Jianfa, WEI Chunling Chinese Space Science and Technology    2024, 44 (4): 71-89.   DOI: 10.16708/j.cnki.1000-758X.2024.0059 Abstract （434）      PDF（pc） （2018KB）（960）       Knowledge map    The accumulation of space debris，the deployment of large-scale satellite constellations，and intensified spatial competition have led to a rapid increase in the number of orbital threats，seriously threatening the safety and stability of spacecraft.Research into spacecraft autonomous decision-making and planning for orbital threats is crucial to securing China's space assets.Confronted with complex scenarios characterized by high dynamics，time-varying constraints，incomplete or imperfect information，and multiple concurrent threats，this research faces several practical challenges.This review examines the research status of spacecraft autonomous decision-making and planning，discusses key technologies including problem modeling，decision-making，maneuver planning，intelligent decision-making and planning，and concludes with suggestions for future research. Related Articles | Metrics

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A dual-loop fault tolerant attitude control for the Chang′e-6 lunar orbit flight ZHANG Honghua, GUAN Yifeng, LI Ji, YU Jie, CHEN Yao, WANG Zhiwen, ZHANG Xiaowen, ZHANG Luchen, LI Linfeng, SUN Guojian, WANG Zhenhua, GUO Minwen, LI Xiaofeng, GAO Xizhen Chinese Space Science and Technology    2024, 44 (5): 15-22.   DOI: 10.16708/j.cnki.1000-758X.2024.0070 Abstract （419）      PDF（pc） （4634KB）（378）       Knowledge map    During the lunar orbit flight phase of the Chang′e-6 lander and ascender module (LAM), the 10N thruster (could be used in a force-couple method) on the ascender and the 150N thruster on the lander are implemented for the attitude control. However, there exists some fault cases when one 10N thruster failed to fire and the other pair one could work well, the propulsion system could generate opposite control torque due to the installation of thrusters and the attitude could be instable accordingly. To ensure the attitude stability in the 10N thruster fault case, a dual-loop fault tolerant attitude control is proposed with a 10N thruster in the inner loop and a 150N thruster in the outer loop. Numerical simulations illustrate that the LAM attitude in the lunar orbit could still meet the requirements even in the case of the 10N thruster fault. Therefore, the proposed dual-loop attitude control, which implements coupled attitude control thrusters and redundant thrusters, could effectively manage the coupled thruster fault and ensure the stabitlity. Related Articles | Metrics

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Microwave power transmission technologies for space solar power station YANG Bo, SHINOHARA Naoki Chinese Space Science and Technology    2025, 45 (2): 1-14.   DOI: 10.16708/j.cnki.1000-758X.2025.0017 Abstract （419）      PDF（pc） （5906KB）（198）       Knowledge map    The microwave wireless power transmission technologies for space solar power station are a crucial field in the international space sector, where various countries are competing in its development. This paper surveys the research experiments and development efforts related to space solar power stations and microwave wireless power transmission technologies worldwide. The objective is to assess the progress and current state of this technological foundation, determine the necessary focus for developing high-power microwave wireless power transmission technology, and provide clarity on the direction of future technology development in these areas. Finally, a distributed space solar power station plan that is immediately feasible is proposed. 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 Chinese Space Science and Technology    2025, 45 (1): 34-45.   DOI: 10.16708/j.cnki.1000-758X.2025.0004 Abstract （404）      PDF（pc） （7312KB）（251）       Knowledge map    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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Equilibrium of orbital pursuit-evasion-defense three-sided game LI Zhenyu, LIN Kunpeng, HOU Yuzhuo, LUO Yazhong Chinese Space Science and Technology    2024, 44 (4): 90-101.   DOI: 10.16708/j.cnki.1000-758X.2024.0060 Abstract （391）      PDF（pc） （7093KB）（593）       Knowledge map    To improve the defense ability of the spacecraft in orbit，an orbital pursuit-evasion-defense（PED）linear-quadratic game is investigated.Three players are called the pursuer，evader，and defender，respectively.The pursuer aims to intercept the evader，while the evader tries to escape from the pursuer，accompanied by a defender who attempts to protect the evader by intercepting the pursuer actively.Due to the existence of the defender，the pursuer has to evade the defender when chasing the evader.Meanwhile，cooperation between the evader and the defender may decrease the difficulty of escape.For such a three-sided game，a linear-quadratic differential game model is established with a performance index combining three players′ energy consumption and the distance.Then the necessary conditions for the Nash equilibrium of the three players are derived and the optimal pursuit guidance law and evasion-defense guidance law are obtained.Furthermore，the equilibrium solution is extended to a more general PED scenario with multiple defenders.Simulation results show that a defender can improve the survivability of the evader.Even with inferiority in maneuverability，they can win the pursuer cooperatively.Besides，an initial position close to the pursuer or evader is not the best choice for the defender who flies around the evader.The defender has favorable positions. Related Articles | Metrics

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Structure and mechanical properties of lunar glasses CHEN Ziqiang, ZHAO Yong, CHI Xiang, YAN Yuqiang, SHEN Jie, ZOU Minjie, ZHAO Shaofan, LIU Ming, YAO Wei, ZHANG Bo, KE Haibo, MA Xiuliang, BAI Haiyang, YANG Mengfei, ZOU Zhigang, WANG Weihua Chinese Space Science and Technology    2025, 45 (3): 1-8.   DOI: 10.16708/j.cnki.1000.758X.2025.0033 Abstract （370）      PDF（pc） （18306KB）（147）       Knowledge map    Glass, a main component of lunar soil, is widely mixed in various forms like particles and agglutinates of small sizes in lunar soil and has good spatial applicability. The good glass-forming ability of lunar soil makes it the preferred raw material for the preparation of space glass materials. However, due to the lack of micro and nano sample preparation and detection methods, the mechanical properties of lunar glasses are rarely reported before, which seriously restricts the service evaluation of such glassy materials. In this study, the microstructures and mechanical properties of five typical Chang'e-5 lunar glassy particles are systematically studied by means of micro and nano sample preparation and mechanical testing combined with transmission electron microscopy (TEM) characterization. The results show that the lunar glasses have flexible and changeable (homogeneous to nano scaled inhomogeneous) amorphous structures and broad controllable mechanical properties (hardness ranges from (6.1±0.4)GPa to (8.4±0.2)GPa, modulus ranges from (48.5±1.9)GPa to (88.4±2.4)GPa). In addition, there is a marvelous decoupling phenomenon between the hardness and modulus of the lunar glasses, i.e., the rejuvenation process (heating them up to the supercooled liquid region and then cooling down to room temperature at fast cooling rates) greatly reduces the modulus while has much weaker effects on the hardness, which is attributed to the deformation mode changed from densification to shear flow. The rejuvenation process will induce volume expansion and inhomogeneous structure in the lunar glasses, which will facilitate such deformation change, leading to hardening effects. The results can provide guidance for the research and development of high-performance glassy materials for space application. 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 Chinese Space Science and Technology    2025, 45 (1): 46-58.   DOI: 10.16708/j.cnki.1000-758X.2025.0005 Abstract （354）      PDF（pc） （5406KB）（231）       Knowledge map    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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Fuzzy gain-adapting coupling attitude control for under-actuated spacecraft MENG Zhongjie, LU Junjie Chinese Space Science and Technology    2024, 44 (4): 11-19.   DOI: 10.16708/j.cnki.1000-758X.2024.0053 Abstract （336）      PDF（pc） （3949KB）（371）       Knowledge map    During rapid orbital maneuvers，aiming at the strong attitude disturbance problem caused by thrust misalignment and installation errors under solid propulsion，an underactuated spacecraft intelligent attitude control method based on thrust vector control technology is proposed.Firstly，the dynamic model of spacecraft attitude error is established，and the underactuated characteristic of thrust vector control inputs are analyzed.Then，considering the issues of strong disturbance uncertainty and weak coupling in the roll channel，an underactuated intelligent control law based on enhanced coupling strategy and adaptive fuzzy observer is designed.The fuzzy logic function is used to approximate the strong disturbance uncertainty term and introduced into the control law to achieve underactuated intelligent attitude control of spacecraft.The stability of the system has been proven through Lyapunov theory.Finally，through numerical simulation and comparison with the hierarchical sliding mode control method，the simulation results show that the designed method can shorten the three-axis attitude stability time by 14%，and can effectively eliminate the static error caused by weak roll channel，which provides a foundation for strong disturbance suppression technology during rapid orbital maneuvers. Related Articles | Metrics