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Advances and prospects of the configuration design and control research of the LEO mega-constellations RUAN Yongjing, HU Min, YUN Chaoming Chinese Space Science and Technology    2022, 42 (1): 1-15.   DOI: 10.16708/j.cnki.1000-758X.2022.0001 Abstract （851）      PDF（pc） （4662KB）（2158）       Knowledge map    In recent years, the LEO constellation programs have developed rapidly and become a “new battlefield” in the global competition of space strategic resources. Firstly, up-to-date status of LEO megaconstellations was described, and the current status of LEO mega-constellations in China was introduced. Configuration design methods and characteristics of constellation were summarized from four aspects, including mission requirements, coverage characteristics, perturbation compensation and spare strategy. Then, according to the whole control process of satellite constellations configuration from orbit to departure, the methods and characteristics of initialization control, stationkeeping control, reconfiguration control, constellation collision avoidance control and de-orbit control were reviewed. Finally, the future research aspects of the configuration design and configuration control technology of the LEO mega-constellations were looked into. Related Articles | Metrics

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Cloud detection methods for remote sensing images：a survey LIU Zili, YANG Jiajun, WANG Wenjing, SHI Zhenwei Chinese Space Science and Technology    2023, 43 (1): 1-17.   DOI: 10.16708/j.cnki.1000-758X.2023.0001 Abstract （1059）      PDF（pc） （3043KB）（1753）       Knowledge map     The cloud cover in the optical remote sensing images will obscure the ground information in different degrees，which causes the blurring and missing of the surface observation information and greatly affects the imaging quality of remote sensing images.Therefore，the detection and evaluation of cloud cover in remote sensing images are the basis and key to further analyze and utilize remote sensing image information.Through sufficient investigation and summary，the development trend and representative work of cloud detection methods based on remote sensing images at home and abroad since the 1990s were combed.Cloud detection methods based on remote sensing images were divided into three categories：methods based on band threshold，methods based on classical machine learning and methods based on deep learning.Besides，the public datasets at home and abroad used in the related research on cloud detection were summarized，and the accuracy of some representative cloud detection methods was compared.In addition to the vanilla cloud detection method，the cloud/fog（haze）detection，cloud/snow detection，cloud shadow detection and cloud removal methods related to cloud detection were also briefly combed.Based on the review and summary of cloud detection work above，the existing problems and future development trends of cloud detection were analyzed and prospected. Related Articles | Metrics

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GEO satellite communication link budgets calculation and analysis XU Ting, LAN Hai, ZHANG Hongjiang Chinese Space Science and Technology    2020, 40 (3): 83-92.   DOI: 10.16708/j.cnki.1000-758X.2020.0035 Accepted: 20 January 2020 Abstract （1096）      PDF（pc） （3338KB）（1967）       Knowledge map    As an important technology, satellite-ground link budget calculation is the theoretical basis of satellite communication system designing which directly decides the link availability. As there are many factors which may affect the satellite link, any unreasonable factor in the design would make the whole satelliteground link unavailable and leads to a big loss. Moreover, there is no ideal satellite link situation unless overlooking some factors, which is also a difficulty during the link budget calculation. Based on the international common calculating method, GEO satellite link was analyzed thoroughly, separating the whole link into uplink and downlink. Then a practical example was analyzed and calculated according to the project experience in LAOSAT Company. At last, different reasonable designing methods in terms of different link configurations were obtained, which could be the references to link calculation and analysis of GEO satellite communication. Related Articles | Metrics

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Review and prospect of intelligent perception for non-cooperative targets MU Jinzhen, HAO Xiaolong, ZHU Wenshan, LI Shuang Chinese Space Science and Technology    2021, 41 (6): 1-16.   DOI: 10.16708/j.cnki.1000-758X.2021.0076 Abstract （618）      PDF（pc） （1102KB）（1454）       Knowledge map    Intelligent perception is the key technology to realizing the fine control process of spacecraft on-orbit, which is one of the major development directions of on-orbit intelligence service. The key technologies of space target intelligent perception include pose measurement, three-dimensional reconstruction and component recognition, which involve the issues such as few-shot, multi-modality, model adaptation and high-dimensional data. From the perspective of engineering application, the latest research progress in the non-cooperative intelligent perception technique was systematically summarized. Firstly, the research status of the representative non-cooperative on-orbit perception systems and optical sensors were reviewed. Secondly, the key technologies involved in the intelligence perception of non-cooperative targets were analyzed. Finally, according to the analysis of the research status and critical techniques, the main issues of non-cooperative target intelligent perception were discussed, and the recommendations for the further development were presented. Related Articles | Metrics

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Progress and prospect in planetary exploration of solar system YANG Mengfei, ZHENG Yanhong, NI Yanshuo, HUANG Xiaofeng, ZHANG Zhengfeng, XING Zhuoyi Chinese Space Science and Technology    2023, 43 (5): 1-12.   DOI: 10.16708/j.cnki.1000-758X.2023.0063 Abstract （525）      PDF（pc） （10199KB）（697）       Knowledge map    Planetary exploration is an important means of humans to understand the universe.With the continuous development of space technology，major space countries have carried out more than 100 planetary exploration activities in the solar system.Humans have realized the flyby，orbiting，lander，rover and sample return missions of solar system.Based on the implemented planetary exploration activities and upcoming missions，the main scientific issues and discoveries of planetary exploration were summarized.And the development tendency of planetary exploration was analyzed.According to the recent development plan of planetary exploration in China，a medium to longterm conceiving route and flagship mission have been proposed.It can provide support for the planning of future planetary exploration missions in China. Related Articles | Metrics

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Review of blackout mitigation methods for vehicles during atmospheric reentry YU Minghao, QIU Zeyang Chinese Space Science and Technology    2022, 42 (2): 1-12.   DOI: 10.16708/j.cnki.1000-758X.2022.0016 Abstract （362）      PDF（pc） （2375KB）（1169）       Knowledge map    In order to help researchers better understand the mitigation methods of blackout and its development status, blackout mitigation methods adopted in current aerospace fields were introduced systematically and comprehensively. Firstly, the formation causes and research status of blackout problem were briefly introduced, and then the propagation mechanism of electromagnetic wave in plasma was also expounded. Secondly, the basic principles, advantages and disadvantages of 14 technical methods used to mitigate the blackout were introduced and discussed in detail. Those methods include variation of aerodynamic design of aircrafts, addition of the crossed electric and magnetic fields, standing wave detection, increment of the incident frequency, and terahertz technology, etc. Next, the abovementioned 14 methods were classified and evaluated from six aspects, e.g., power consumption, size quality, communication effect and engineering practicability, etc. Finally, several suggestions are put forward for the future study of the blackout problem. Related Articles | Metrics

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Resource allocation in high throughput multibeam communication satellite systems WANG Lei, ZHENG Jun, HE Chuan, YAN Xuefei Chinese Space Science and Technology    2021, 41 (5): 85-94.   DOI: 10.16708/j.cnki.1000-758X.2021.0070 Abstract （385）      PDF（pc） （3765KB）（790）       Knowledge map    Resource allocation plays an important role in the performance of new generation of high throughput multibeam communication satellite(HTMCS) systems. The static and single dimension methods for resource allocation were normally proposed for previous communication satellite systems with non-flexible payloads and uniform distribution of users’ capacity demands, which has seriously constrained the performance of the HTMCS systems. A joint power and bandwidth resource allocation model for the HTMCS systems was built, with the consideration for beam interference, flexible payloads and nonuniform distribution of capacity demands. Meanwhile, a genetic algorithm with high efficient search control strategies was implemented to solve this model. Finally, several types of dataset were employed with different capacity demands and distribution profile between beams to verify the proposed method. Experimental results show that the method can reduce the unmet capacity demand(UCD) by 71.09%, 40.47% and 16.31% compared to the current static method for the total capacity demand of 90Gbit/s, 110Gbit/s and 130Gbit/s respectively. Related Articles | Metrics

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Progress and prospect of lunar resources exploitation and utilization YANG Mengfei, ZOU Zhigang, WANG Weihua, YAO Wei, WANG Qinggong Chinese Space Science and Technology    2024, 44 (1): 1-10.   DOI: 10.16708/j.cnki.1000-758X.2024.0001 Abstract （430）      PDF（pc） （4467KB）（554）       Knowledge map    With the implementation of the Chang′E-5 mission in 2020，the three phases of China lunar exploration program，namely orbiting，landing and returning，have been completed.Next，the International Lunar Research Station（ILRS）will be established at the lunar south pole by 2030，and a lunar base will be planned later.It is a new era of exploitation and utilization of the Moon，in which a vast tasks should be completed.In this paper，we summarized some important progresses of investigation of lunar resources in the past，including lunar resource exploration，analysis of lunar volatiles，mineral extraction，and material construction by 3D printing of lunar regolith.Then，we proposed future tasks for the exploitation of the lunar resources.The main challenges of the Moon，such as the extreme lunar environment，unique properties of lunar regolith，and autonomous control of the process，were considered.The views in this paper can be referenced for future scientific researches and engineering tasks in the field. Related Articles | Metrics

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Rapidthermaldeformationanalysisofon-orbitsatellitesonthebasisofstatisticmethod ZHANG Ye-Chi, ZHANG Long, LUO Wen-Bo, PAN Teng null    2016, 36 (6): 55-61.   DOI: 10.16708/j.cnki.1000-758X.2016.0062 Abstract （703）      PDF（pc） （6812KB）（1249）       Knowledge map    Tocalibratetheorientationpositionofthesatelliteorbitbythetemperaturesensors，theordinaryKrigingmethodwidelyusedingeo-statisticswasappliedintothetemperatureestimationprocessofthesatellite.Arapidthermaldeformationanalysismethodwasdevelopedbasedonthestatisticmethods.Basedonasmallamountoftemperaturesensors，estimationofthetemperaturefieldwascarriedout.Then，thetemperaturefieldwasusedforthefiniteelementanalysistoaccomplishthethermaldeformationanalysis.Differencesbetweentheanalyticalandtheexperimentalresultsofthedeformationofthepayloadarearound1′，whichconfirmsthatthemethodcanbeusedtoobtainthevariationofopticalaxisofthepayload.Furthermore，comparedtothethermophysicalmethod，theworkperiodcanbereducedbyseveraldays.Thisworkprovidesguidanceforrapidthermaldeformationanalysisofon-orbitsatellites. Related Articles | Metrics

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A review for space-based ADS-B NI Jiushun, CHEN Lihu, YU Sunquan, LI Songting, GUO Jianming, LUO Aobo, LI Jinhua Chinese Space Science and Technology    2022, 42 (1): 30-37.   DOI: 10.16708/j.cnki.1000-758X.2022.0003 Abstract （278）      PDF（pc） （4911KB）（813）       Knowledge map    As an important technology of air traffic control in the future, space-based ADS-B technology can overcome the difficulties of ground equipment deployment in desert, ocean, polar and other places. The space-based ADS-B technology has the characteristics of a wide range of reconnaissance and reception, which can cover the whole world, and relevant studies have been carried out in many countries. According to the frontier characteristics of ADS-B technology, the research progress of ADS-B technology is investigated. First of all, the principle and related research of ADS-B are summarized. Secondly, the key technologies of ADS-B reception on board are reviewed from four aspects: antenna technology, radio frequency circuit technology, signal processing and constellation design method. Finally, the application of ADS-B data and its future development prospect are described. Related Articles | Metrics

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Development of advanced electric propulsion technology for cislunar and deep space exploration WU Chenchen, GENG Hai, WANG Zitong, LI Detian Chinese Space Science and Technology    2023, 43 (5): 13-23.   DOI: 10.16708/j.cnki.1000-758X.2023.0064 Abstract （287）      PDF（pc） （7207KB）（422）       Knowledge map    Space electric propulsion is the key technology of cislunar and deep space exploration.Space electric propulsion technology，one of the key technology of cislunar and deep space exploration,was focused on.The technical connotation of space electric propulsion and its application status in China was introduced，and the typical international cislunar and deep space exploration missions based on electric propulsion was analyzed from the dimensions of mission characteristics，electric propulsion configuration，and application benefits.Aiming at the future development needs of China’s deep space exploration，the optimization application stratrgies of electric propulsion were introduced for five typical scenarios: lunar exploration，asteroid exploration，human Mars exploration，solar system boundary exploration and cislunar space scientific exploration，and the key technical systems and development priorities of advanced electric propulsion for deep space exploration were sorted out.Finally，according to the development idea of “one medium，one super，one micro”，suggestions on space electric propulsion technology development were given，which provide a reference for a wider range of applications of space electric propulsion in the field of cislunar and deep space exploration. Related Articles | Metrics

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Recent progress and prospect of hightemperature heat pipes technology LI Jin-Wang, DAI Shu-Gang null    2019, 39 (3): 30-.   DOI: 10.16708/j.cnki.1000-758X.2019.0018 Abstract （1036）      PDF（pc） （1715KB）（1732）       Knowledge map    Hightemperature heat pipes have a good heat transfer performance and can be used for high working temperature. They have an expansive application prospect in the field of thermal protection system of hypersonic vehicle, cooling of space reactor and utilization of solar energy, and so on. The recent progress of hightemperature heat pipes is reported,including the startup characteristic from the frozen state and heat transfer performance of hightemperature heat pipes, the experimental studies, the numerical analysis studies. The effects of the inclination angles, the working fluid parameters, the fill charge ratio, the noncondensable gas, the material, the structure and the sizes on the startup characteristic from the frozen state and heat transfer performance of hightemperature heat pipes are presented.The applications of hightemperature heat pipes for thermal management of hypersonic flight vehicles, cooling of space reactor and utilization of solar energy are summarized. The future development direction is also pointed out, such as the numerical analysis model and engineering application of hightemperature heat pipes. The future research suggestions of hightemperature heat pipes are also put forward. Related Articles | Metrics

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3D printing densification of lunar regolith simulant LIU Yiwei, ZHANG Xian, WANG Chao, SONG Jian, CHEN Xiong, Yao Wei Chinese Space Science and Technology    2023, 43 (6): 66-73.   DOI: 10.16708/j.cnki.1000-758X.2023.0085 Abstract （179）      PDF（pc） （7898KB）（405）       Knowledge map    The insitu 3D printing of lunar regolith（additive manufacturing）can realize the in-situ construction of the lunar base and the insitu manufacturing of key components，and can greatly reduce the cost and risk of the lunar exploration mission.A selective laser melting lunar regolith simulant experiment system was built to carry out single-track molding experiments to explore the effect of the first powder layer thickness on the densification of the sample，while the width and depth of each track were measured.The results show that the width of the single-track decreases with increasing scanning speed until the width is almost constant.At the same laser power，the single-track depth becomes deeper as the first powder layer thickness increases.The singletrack depth increases and then decreases with the increase in scanning speed.The density of a single-track can reach 2.5g/cm3，and the relative density is 86%.As the scanning speed increases，the density of single-track for different layer thicknesses is stabilized at 1.7g/cm3.When the first layer of powder is thinner，the density of single-track is also slightly higher than other layer thicknesses. Related Articles | Metrics

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Opportunities and challenges of longdistance high-capacity continuous wireless power transmission LI Ming, DONG Shiwei, SHI Dele Chinese Space Science and Technology    2023, 43 (3): 1-13.   DOI: 10.16708/j.cnki.1000-758X.2023.0033 Abstract （294）      PDF（pc） （1058KB）（382）       Knowledge map    Long-distance high-capacity continuous wireless power transmission（WPT）is one of the candidate routes to realize space-based solar power exploitation and carbon neutrality.Firstly，the application demands and development opportunities were introduced with specific technical requirements for practical applications of long-distance high-capacity continuous WPT.Secondly，the international state-of-the-art research progress was reported.Then technical challenges were discussed，with respect to development trend and application needs.And toward these challenges，development suggestions were proposed. Related Articles | Metrics

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LEO constellation configuration design method with constant trajectory of subsatellite points ZHANG Yasheng, JIA Lu, YU Jinlong, LIANG Shuang Chinese Space Science and Technology    2023, 43 (3): 116-122.   DOI: 10.16708/j.cnki.1000-758X.2023.0044 Abstract （291）      PDF（pc） （5014KB）（350）       Knowledge map    An analytical design method for the LEO constellation configuration with constant trajectory was provided，where all satellites share a common subsatellite trajectory and the trajectory is fixed.The constellation configuration was coded with two parameters，the regressor and the number of satellites.Firstly，based on the idea of average orbital elements，an analytical model of repeat ground track orbit design was established under the condition that the harmonic order of the Earth’s non-spherical perturbation band is J4.Secondly，according to the relative motion law of the satellite and Earth，the analytical formula satisfying the common trajectory condition was established.Finally，the constellation configuration design model of the LEO constant trajectory constellation was constructed by combining the concept of repeat ground track orbit design and common trajectory design.The ultimate simulation results show that the configuration design method meets the design expectation，which verifies the effectiveness of this configuration design method.The constellation configuration is characterized by simple form，easy maintenance，and wide coverage.It guarantees the consistency of orientation between the space system and ground system，which greatly reduces the complexity of satellite-ground system cooperation. Related Articles | Metrics

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Software defined TT&C system architecture and key technology LI Chao, JIAO Yiwen, FU Shiyuan, WU Tao Chinese Space Science and Technology    2023, 43 (3): 14-24.   DOI: 10.16708/j.cnki.1000-758X.2023.0034 Abstract （257）      PDF（pc） （6999KB）（340）       Knowledge map    In order to meet the rapidly changing needs of civil and commercial aerospace TT&C and the explosive growth of TT&C tasks caused by the rapid development of small satellites and large constellations，software-defined technology，which is considered a revolutionary technology that changes the rules of the game，was introduced from the internet industry into aerospace TT&C systems，a software-defined aerospace TT&C system architecture was proposed，and a new round of technological innovation in the TT&C system was realized.Firstly，the architecture and existing problems of the traditional TT&C system were analyzed，and then the technical characteristics of the software-defined aerospace TT&C system were discussed，such as hierarchical design standards，open application interfaces，centralized system control，and flexible reorganization of basic resources.Then，the advantages of the architecture and four key technologies including standard interfaces and specifications，software-defined RF front-end，software-defined channel and softwaredefined baseband were analyzed，and the development of software-defined TT&C system was prospected.The research results show that compared with the traditional TT&C system，the software-defined aerospace TT&C system architecture can better meet the needs for TT&C resources of the growing aerospace industry. Related Articles | Metrics

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MobilitymanagementinLEOsatellitecommunicationnetworks HE Da-Jian, YOU Peng, YONG Shao-Wei null    2016, 36 (3): 1-14.   DOI: 10.16708/j.cnki.1000-758X.2016.0034 Abstract （1094）      PDF（pc） （1144KB）（2786）       Knowledge map    Inrecentyears,lowEarthorbit(LEO)satellitecommunicationnetworksattractalotofresearchers'attentionforitsglobalcoverage,shortpropagationdelay,low-powerlinksandgreatinvulnerabilityperformance，etc.Itwillbeanimportantpartofthefutureglobalmobilecommunicationsystems.MobilitymanagementisakeytechnologyforenablingserviceinLEOsatellitecommunicationnetworks.Thecharacteristics,researchstatusandproblemsofmobilitymanagementwereanalyzed.Firstly,abriefclassificationofmobilitymanagementofLEOsatellitecommunicationsnetworkswasprovidedandcharacteristicsdistinguishedfromterrestrialmobilitywirelessnetworkswereanalyzedbasedonthearchitectureandfeaturesofLEOsatellitecommunicationnetworks.Thenthestate-of-the-artmobilitymanagementschemesinLEOsatellitecommunicationnetworksweresummarizedfromlinklayer,networklayerandtransportlayer.AdetaileddescriptionoftheapplicationofMIPv6andSIGMAinLEOsatelliteenvironmentwasgiven.Finally,sometrendsofmobilitymanagementofLEOsatellitecommunicationsnetworkswaspointedout. Related Articles | Metrics

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System design and key technolongies of the GF-7 satellite CAO Haiyi, ZHANG Xinwei, ZHAO Chenguang, XU Chi, MO Fan, DAI Jun Chinese Space Science and Technology    2020, 40 (5): 1-9.   DOI: 10.16708/j.cnki.1000-758X.2020.0052 Abstract （712）      PDF（pc） （5941KB）（943）       Knowledge map    GF-7 satellite is the first 1∶10000 scale stereoscopic surveying and mapping satellite independently developed in China, and an important part of the national high resolution earth observation system. The satellite is based on the active and passive combined surveying and mapping system of “two-line array surveying and mapping + laser altimetry” and forms a series of key technologies and innovation points, such as highprecision internal/external element stability design, highprecision attitude stability control, the first X-band adaptive high-rate data transmission system, and onboard intelligent satellite management system. The capability of large scale stereoscopic mapping with little or no control points was realized. The system design of the satellite was described, and the technical innovation points were summarized such as observation system, high-precision load, attitude control, digital data transmission, intelligent satellite service, etc. The preliminary evaluation was carried out through the test results of satellites in orbit, and the satellites can meet the requirements of the 1∶10000 surveying and mapping mission. Related Articles | Metrics

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Research and prospect of scientific exploration for Jovian system ZOU Xin, PENG Jing, MIAO Yuanming Chinese Space Science and Technology    2023, 43 (6): 1-10.   DOI: 10.16708/j.cnki.1000-758X.2023.0078 Abstract （269）      PDF（pc） （3340KB）（325）       Knowledge map    In order to make a better plan for China′s scientific exploration for Jovian system，the development status of foreign Jovian system exploration missions were investigated and analyzed.Among the nine space missions that explored Jupiter and its satellites so far，seven are flyby missions.The other two are Galileo and Juno particularly for Jupiter.The Scientific goals，payloads configuration and exploration results were extracted and generalized.The mission characteristics and enlightenment of scientific exploration for Jovian system were obtained.Finally，on the basis of the above analysis and pending problems，the primary mission layout and prospect of scientific exploration for Jovian system in China were proposed. Related Articles | Metrics

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Radiometric Calibration and Accuracy Analysis based on Spaceborne SAR TAO Man-Yi, JI Peng, HUANG Yuan-Bao, JIANG Yan null    2015, 35 (5): 64-70.   DOI: 10.3780/j.issn.1000-758X.2015.05.009 Abstract （944）      PDF（pc） （3082KB）（924）       Knowledge map    With the development of spaceborne synthetic aperture radar(SAR)application,the radiometric calibration technology was used to observe objects′ physical characters.    Because the radiometric calibration technology is very complex,on the study of radiometric calibration and accuracy analysis will be mostly focused in the strip mode with single channel and single polarization.Firstly,the radar equation was derivated,then with the measured calibration constant,the short-term and long-term relative calibrations were studied based on an error model and formula. At the same time,the influence of calibration constant for absolute radiometric precision was analyzed and the system correct was finished.Finally the validated result on TerraSAR-X satellite shows that the difference of the calculated value and the measured one is less than 0.05dB. Related Articles | Metrics