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09 September 2022, Volume 42 Issue 5 Previous Issue   

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Progress and prospect of solar exploration in space YANG Mengfei, DAI Shuwu, WANG Ying, ZHU Chenglin, YANG Shangbin, ZHANG Yechi 2022, 42 (5):  1-10.  doi: 10.16708/j.cnki.1000-758X.2022.0062 Abstract ( 413 )   PDF (2853KB) ( 403 )   Save  In order to explore the development direction of solar space exploration activities，ten typical probes were selected taking into account their implementation era，orbital design，exploration elements，technical characteristics and each mission′s result based on extensive research on solar probe missions.Scientific objectives，payloads，satellite platform characteristics and scientific achievements of the ten typical probes were analyzed.Solar space exploration progress and development trend were summarized.In general，the orbit of solar detectors has been gradually diversified，detection elements of payload have become more abundant，and the detection accuracy and resolution have been significantly improved.However，there are still a lot of problems to be solved.On the basis of analyzing the current achievements and pending problems，the development outlook of solar space exploration was proposed，pointing out that all round and multielement exploration is a feasible way to break the bottleneck of solar physics and space weather forecast. Related Articles | Metrics

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Review of the research on spacecraft end-of-life de-orbit technology KANG Huifeng, MEI Tianyu, XIA Guangqing, WANG Xiaoyang, FAN Yipeng, LU Chang 2022, 42 (5):  11-23.  doi: 10.16708/j.cnki.1000-758X.2022.0063 Abstract ( 291 )   PDF (2258KB) ( 495 )   Save To purify the space environment，the existing spacecraft de-orbit technologies were analyzed for the spacecraft de-orbit problem at the lifetime end.The research status of spacecraft end-of-life de-orbit technologies was introduced.The characteristics and applicability of various de-orbit methods were summarized.Then the development trends and key technologies of various de-orbit methods were analyzed，and the development suggestions for the de-orbit technologies at the lifetime end of the spacecraft were put forward.The results show that the spacecraft end-of-life de-orbit technologies can de-orbit spacecraft within 25 years，but the reliability of de-orbit device，the stability of deorbit，the deorbit time of spacecraft and the aftertreatment can still be greatly improved. Related Articles | Metrics

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Analysis of the first stage deployment of Starlink constellation based on TLE XUE Wen, HU Min, RUAN Yongjing, YUN Chaoming, SUN Tianyu 2022, 42 (5):  24-33.  doi: 10.16708/j.cnki.1000-758X.2022.0064 Abstract ( 563 )   PDF (7069KB) ( 575 )   Save  In recent years，with the rapid development of satellite technology and the increasing demand for low earth orbit（LEO）satellite broadband internet construction，the development of LEO large-scale constellations is changing rapidly.Aiming at the initial deployment of Starlink constellation，firstly，the current status of the Starlink constellation was discussed，and the altitude changes of orbiting satellites were analysed.Then，the deployment of the Starlink constellation was briefly analyzed from two aspects by utilizing the public two-line element（TLE），including satellite being launched into orbit and orbital plane distribution，and the changing rule of ascending node was given.At the same time，the ground coverage performance of the Starlink constellation was simulated and analyzed.Finally，the constellation orbital planes and phase distribution，handling of the faulty satellites，and the number of visible satellites were obtained.The results of the analysis are expected to provide reference for China′s future deployment of large-scale LEO constellations. Related Articles | Metrics

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Research on DTN integrated transmission performance constraints for spatial communication YANG Guannan, ZHAO Kanglian, FENG Tao, LI Song, LIU Jinliang 2022, 42 (5):  34-43.  doi: 10.16708/j.cnki.1000-758X.2022.0065 Abstract ( 190 )   PDF (5089KB) ( 229 )   Save Compared with the terrestrial network，the spatial communication link has the characteristics of long delay，frequent interruption，high bit error rate，and asymmetric uplink and downlink.The mature network technology of the internet is not suitable，which challenges the guarantee of reliable transmission performance of network.Different from the scheme of spatial IP protocol system，DTN（delay tolerant networking）protocol architecture compatible with various transmission mechanisms according to the spatial communication link characteristics was adopted.Focusing on the link asymmetry and channel error rate，the performance constraints of TCP and LTP（Licklider transport protocol）transmission mechanisms to ensure reliable transmission were studied，and the cross layer packet size optimization model of LTP mechanism was given.Based on the hardware in the loop simulation platform，the space communication scenario below GEO was constructed，and the real data flow simulation was carried out to analyze the impact of link factors on the transmission performance of the protocol.The simulation results show that TCP mechanism can still be used to ensure reliable transmission in the space communication scenario with low bit error rate and channel asymmetry，but LTP transmission mechanism should be considered to ensure the effectiveness and reliability of communication in the communication scenario with high bit error rate and channel asymmetry. Related Articles | Metrics

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Research on variable coding and modulation application efficiency of LEO remote sensing satellite at Ka-band WANG Zhongguo, WANG Dabao, ZHAO Pengfei, ZHANG Shasha, WU Xiaodong, ZHANG Xiao, WANG Zhenxing 2022, 42 (5):  44-56.  doi: 10.16708/j.cnki.1000-758X.2022.0066 Abstract ( 187 )   PDF (7488KB) ( 207 )   Save The increasing resolution of LEO（low earth orbit） remote sensing satellite puts forward an urgent demand for improving the ability of satellite-to-ground data transmission,which results in much pressure on X-band.The usable bandwidth of Ka-band is four times of X-band,which can promote the transmission capacity theoretically.At present,constant coding and modulation (CCM) and variable coding and modulation (VCM) are usually used in data transmission systems from LEO remote sensing satellites to ground stations.The improvement of channel conditions caused by the reduction of atmospheric attenuation when the elevation angle increases was not used,resulting in a waste of link resources.To solve the problem,for specific ground station and link availability,considering the characteristic that the free space loss and atmospheric attenuation decreased with the increasing of elevation angle,the VCM scheme of Ka-band based on DVB-S2（digital video broadcasting-satellite-2nd generation）was promoted,and the evaluation standard of transmission efficiency was given.The transmission efficiency of CCM and VCM at Kashgar,Beijing and Sanya stations with different rainfall characteristics at Ka-band was compared and analyzed,so as to find out the satellite-to-ground data transmission scheme for different ground stations.The simulation results show that the dry Kashgar station is more suitable for adopting CCM,and the link availability is as high as 99.82%.Beijing station with moderate rainfall is suitable for both CCM and VCM,and can be set according to users′ needs.However,Sanya station with abundant rainfall is more suitable for VCM,which not only makes the transmission efficiency factor increased by 8.37%,but also makes the link availability increased by 11.23%. Related Articles | Metrics

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ANN inversion model for electron flux based on deep charging ZHOU Hongtao, FANG Meihua 2022, 42 (5):  57-64.  doi: 10.16708/j.cnki.1000-758X.2022.0067 Abstract ( 113 )   PDF (5579KB) ( 95 )   Save  To realize the estimation of high-energy electron flux and the risk assessment of spacecraft deep charging and discharging，an artificial neural network （ANN）for the electron flux inversion with deep charging was built based on the relation between deep charging and electron flux.The detect currents of a deep charging detector and the electron energy were taken as the model inputs，while the electron fluxes were taken as the output.AE9 was used to train the network，and the MSE of this model was reduced to 0.04122.The deep charging data from Giove-A and electron flux from GOES were used to verify the model′s accuracy.Based on this model，another ANN model was built to calculate the maximum internal electric field of the typical dielectric of spacecraft from the detection current to realize the real-time assessment of charging risk in spacecraft. Related Articles | Metrics

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Changing rules of plume pattern and thermal characteristics in discharge modes of hollow cathodes YU Bo, XU Yanan, KANG Xiaolu 2022, 42 (5):  65-77.  doi: 10.16708/j.cnki.1000-758X.2022.0068 Abstract ( 164 )   PDF (16600KB) ( 128 )   Save There are mainly two discharge modes in hollow cathodes，namely the spot mode and the plume mode.In order to study the transition mechanisms of the two modes，a hybrid model of the PIC（particle in cell）/PCD（plasma and chemical dynamics）was established.This model can solve the plasma parameter distribution in the hollow cathodes，and the heat radiation process can be solved by the radiation transportation coefficient.The solution can be converged after several iterations of the flow-heat coupling calculation.To verify the accuracy of the numerical model，the comparison of the calculation and test results of the 5 measurements on the cathode surface was conducted by a discharge test，and the relative error was less than 5%.Meanwhile，the comparison of the calculated color patterns and the photographs of the cathode plume showed that the numerical model could qualitatively capture the transition of the discharge mode.Based on those，the plasma parameters of the hollow cathode were solved with the PIC/PCD model under the condition of different gas flow rates and different orifice diameters.The mechanisms of the transition mode of the spot-plume discharge were obtained by analyzing the rules of the anode voltage and the plume pattern.This paper can provide the theoretical support for the cathode optimization design. Related Articles | Metrics

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Thermal-structure analysis of modular space deployable antenna support truss structures JIN Lu, ZHANG Feiyang, TIAN Dake 2022, 42 (5):  78-90.  doi: 10.16708/j.cnki.1000-758X.2022.0069 Abstract ( 176 )   PDF (16564KB) ( 117 )   Save The thermal-structure analysis of modular space deployable antenna support truss structure under space thermal alternation is studied，and reasonable protection suggestions are provided for antenna structure's influence on antenna alignment accuracy and network stability due to thermal deformation.A fine numerical model of large aperture modular spatial deployable antenna support structure was established by ANSYS APDL finite element software.Based on the existing experiments，the correctness of finite element modeling and thermal analysis model of modular deployable antenna structure was verified respectively.The influence of constraint position and other parameters on the stress and heat-induced deformation of truss chord and cable under transient temperature field is analyzed.The results show that the development of stress and deformation time history of spatial deployable antenna is basically consistent with the change trend of transient temperature field.Under the same transient temperature field，the thermal stress of the cable in the center module of the antenna structure is the largest，the thermal stress amplitude of the chords of the same circle module is basically the same，the thermal stress of the upper chord increases，and the thermal stress of the cable decreases.The cumulative thermal deformation of the antenna structure is the largest at the farthest end of the distance constraint，and the cumulative thermal deformation at the upper center point can reach about 15mm，which can not be ignored.The thermal deformation of the antenna structure is the least when the tip angle of the module closest to the center of the structure and the joint of the vertical rod with the adjacent module are used as the constraints of the antenna extension arm.In order to reduce the influence of the transient temperature field on the shape precision and deformation of the antenna structure，it is suggested to adopt thermal control coating to improve the adaptability of the antenna structure. Related Articles | Metrics

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Retro-directive microwave power beam steering technology for space solar power station DONG Shiwei, HOU Xinbin, WANG Xin 2022, 42 (5):  91-102.  doi: 10.16708/j.cnki.1000-758X.2022.0070 Abstract ( 311 )   PDF (11662KB) ( 236 )   Save Microwave power transmission（MPT）design and demonstration are key jobs in development of space solar power station（SSPS）in China，while retro-directive microwave power beam steering is a primary part of MPT.Research on retro-directive microwave power beam steering was conducted under the prerequisite that the power transmitting array was with an ideal profile.The position and attitude errors of structural modules had seldom been considered of the power transmitting array in space environment.With respect to the four-phased missions of SSPS development in China，the influence of position and attitude errors on power density at the rectifying array and beam steering error was investigated.After the software retro-directive microwave power beam steering was preliminarily demonstrated，software retro-directive beam steering based on phase compensation was proposed，aimed at correcting the position and attitude errors of array modules.The correction effect was simulated and analyzed.The proposed software retrodirective beam steering based on phase compensation has remarkable correction ability for the position and attitude errors of array modules.This article presents guidelines for MPT system design and assembly. Related Articles | Metrics

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Real-time orbit determination of the ascending and descending process of CE-5 HUANG Pu, ZHANG Chongyang, LI Haiyue, WANG Fan 2022, 42 (5):  103-107.  doi: 10.16708/j.cnki.1000-758X.2022.0071 Abstract ( 180 )   PDF (2376KB) ( 180 )   Save A real-time adaptive “current” statistical method based on three-way measurement was proposed to solve the problem of real-time orbit determination in the process of lunar surface ascending and descending.First,an adaptive current statistical model was used to describe the landing and sampling return process of the lunar process.Second,the method made full use of the measured data which include three-way measurement to update the estimated trajectory.And at last,unscented Kalman filter(UKF) method was used to complete real-time orbit determination.As the adaptive“current”statistical model is very suitable for the complicated trajectory,which includes landing and sampling return,it can solve the orbit determination problem effectively.By processing the measured data of CE-5 lunar process,it shows that this method is more stable and convergent than the traditional method,and has certain application value to deep space target detection. Related Articles | Metrics

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Design and verification of thermal control system for Tianwen-1 Mars entry capsule ZHENG Kai, XIANG Yanchao, RAO Wei, ZHANG Bingqiang, XUE Shuyan, DAI Chenghao, ZHANG Dong, WANG Yuying 2022, 42 (5):  108-116.  doi: 10.16708/j.cnki.1000-758X.2022.0072 Abstract ( 252 )   PDF (2550KB) ( 236 )   Save Tianwen-1 Mars entry capsule took Zhurong Mars rover to accomplish the entry，descent and landing process.Its thermal control system met lots of technical challenges，including wide variations of external heat fluxes during the flight from Earth to Mars，high temperature of entry capsule surface caused by aerodynamic ablation during the Mars entry process，and ultra-high temperature caused by the landing engine during the descent and landing process.Accordingly，comprehensive methods consisting of thermal isolation，thermal transmission and temperature compensation were applied.New thermal control coating SAL-2 was applied to overcome the changes of external heat fluxes.To insulate the ultra-high temperature from the landing engine，a new aerogel-based thermal protector was developed.With these measures，the efficient and reliable thermal control system for Tianwen-1 Mars entry capsule was completely constructed.The in-orbit telemetric data shows that working equipments of Tianwen-1 Mars entry capsule all have suitable temperature ranging from 5.0℃ to 40.3℃ during EDL process，and power consumption for temperature compensation does not exceed 43W，which verifies the effectiveness of this thermal control system. Related Articles | Metrics

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Design of a reflector antenna for Zhu-Rong Mars rover LIU Zhijia, DUAN Jiangnian, HOU Qinfang, SUN Dayuan, ZHUANG Jianlou, LU Fan, LI Fan 2022, 42 (5):  117-124.  doi: 10.16708/j.cnki.1000-758X.2022.0073 Abstract ( 262 )   PDF (6542KB) ( 294 )   Save Considering the requirement of TianWen-1 Zhu-Rong Mars rover′s communication,an X band compact broadband circular polarization reflector antenna was introduced.The novel integrated compact feed technology with length and aperture reduced by 20% was adopted in this reflector.This new feed technology can improve the aperture efficiency of the reflector antenna,and resist the impact of Martian dust.The X-band reflector was optimized,fabricated,and measured.The measured results show that the antenna can reach 62.3% aperture efficiency from 7.1GHz to 8.4GHz frequency band as well as obtain better performance in terms of the gain,the VSWR(voltage standing wave ratio),and the circular polarization in the operating frequency band of the deep space exploration.This novel reflector antenna has been successfully applied to Zhu-Rong Mars rover. Related Articles | Metrics

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Infrared dim small flying target recognition algorithm for space-based surveillance QIAO Mengyu, TAN Jinlin, LIU Yahu, Xu Qizhi, WAN Shengyang 2022, 42 (5):  125-132.  doi: 10.16708/j.cnki.1000-758X.2022.0074 Abstract ( 170 )   PDF (3763KB) ( 112 )   Save Aiming at the problems such as the infrared weak flying targets being not significant，and the difficulty of designing the artificial feature extractor，an infrared dim flying target recognition algorithm was proposed based on deep learning.Similarly，background interference could also be a major problem.Therefore，a detection framework was established to deal with the mentioned problems based on the YOLOv4 model.K-means++ algorithm was used to cluster the candidate frames of the training set.This framework was demonstrated to select the sufficient size of anchor，and it was more reasonable to select one specific sample from the database as the initial center other than picking the initial point randomly.At the same time，the convolutional attention module was introduced into the framework，which not only made a more reasonabe allocation of algorithm resources but also made the information more sensitive in detecting the infrared weak flying targets.Since the spatial pyramid pooling module was well enhanced，more original information about the photograph could be retained by using the average pooling method，which could reduce the effect caused by noise and dead pixels within the space-based imaging process.The experiential simulation illustrates the accuracy can reach 80.13% when calculating the anchor size based on K-means++ modulus.The recognition of the algorithm could even reach 83.3% if adding SPP and CBAM modules to the test set.Furthermore，the accuracy of detecting the infrared weak small flying targets also gains an exceptional improvement after the adjustment on modulus. Related Articles | Metrics

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Calculation method of the coverage region for spaceborne observations above the horizon SUN Yangyuxi, QIAO Dong, ZHANG Chen, ZHU Zhengfan, WEN Changxuan 2022, 42 (5):  133-143.  doi: 10.16708/j.cnki.1000-758X.2022.0075 Abstract ( 143 )   PDF (5514KB) ( 120 )   Save For the increasingly complex space environment，space-based observations have attracted more and more attention due to their flexible distribution and all-weather observation，which is a typical above-the-horizon（ATH）observation problem.Based on the concept of segmental integration，a quantitative calculation method of the coverage region for ATH observations was proposed，which includes all possibilities of 10 integral forms of the problem for scenarios with any observation constraints.Not only has the two-dimensional planar coverage problem been verified with existing methods，but also the quantitative analytical calculation problem of the coverage volume of ATH in three-dimensional space has been solved for the first time.The simulation results show that there is a significant difference between the optimal orbit altitude corresponding to the maximization of planar and spatial coverage.The proposed approaches are more accurate and efficient in coverage performance，providing reference for constellation design. Related Articles | Metrics

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Design of inter-satellite phase interferometer angle measurement system and its precision analysi ZHU Liangwei, LI Mingcheng, WANG Chunhui, JIN Zhonghe 2022, 42 (5):  144-153.  doi: 10.16708/j.cnki.1000-758X.2022.0076 Abstract ( 178 )   PDF (3182KB) ( 226 )   Save Aiming at the problem of relative angle measurement in multisatellite cooperative missions such as satellite formation flying and inter-satellite networking,a high-precision radio angle measurement system was proposed.It was realized by adding two same receiving channels on the basis of PN code ranging system.The system used carrier phase combined with phase interferometry to obtain high-precision inter-satellite relative angle.The advantage of the system is that it can complete the real-time and high-precision inter-satellite relative state autonomous measurement without additional hardware and software overhead.Starting with the design of the system,a detailed precision analysis of the phase interferometer angle measurement system was carried out.Then the transfer function and theoretical noise level of each noise in the link were derived.A physical platform was built to compare the theoretical value and the measured value of the angle measurement accuracy.The results show that the system has a suppressive effect on the phase noise of the local oscillator,and thermal noise is the largest noise source for angle measurement.The angle measurement accuracy of the system can reach 1.4×10-3 degrees under strong signal conditions. Related Articles | Metrics

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Steering law design for hybrid actuator based on optimal output torque capability NI Rui, HUA Bing, ZHANG Hong, WU Yunhua, CHEN Zhiming 2022, 42 (5):  154-165.  doi: 10.16708/j.cnki.1000-758X.2022.0077 Abstract ( 121 )   PDF (4404KB) ( 127 )   Save When spacecraft perform high dynamic agile maneuver or attitude dynamic tracking control tasks,the hybrid actuator composed of control moment gyroscope (CMG) and reaction wheel (RW) was often used to provide control torque.A control law of hybrid actuator based on the optimization of torque output capability was proposed.From the geometric point of view,the angular velocity and RW angular acceleration of CMG frame with the optimal torque output capability were given.By introducing the parameter,the mixed quadratic form of frame speed error and output torque error was minimized,and the output torque error of the hybrid actuator was minimized under the condition of optimal torque output capacity.Taking the hybrid actuator composed of pyramidal CMG cluster and orthogonal RW cluster as an example,the control law of hybrid actuator based on the optimization of torque output capacity was rationalized,the effect of introducing parameter was proved,and it was proved that there was no CMG singularity in hybrid actuator.The simulation results show that the hybrid actuator control law based on the optimization of torque output capability solves the problem of CMG singularity and makes RW not fall into saturation,and the output torque error is small. Related Articles | Metrics