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    25 February 2020, Volume 40 Issue 1 Previous Issue   
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    Emergency return analysis of hybrid trajectory based on one impulse for human lunar mission
    LYU Pengwei, SHANG Zhi, WANG Ping
    2020, 40 (1):  1.  doi: 10.16708/j.cnki.1000-758X.2020.0001
    Abstract ( 63 )   PDF (3881KB) ( 47 )   Save
    For human earthmoon transfer mission, emergency return trajectories are key to astronauts′ safe return to earth. Emergency return trajectories based on human translunar hybrid trajectory were proposed, considering safety the most important requirement in human earthmoon transfer mission. There are three emergent return methods,which are direct return, immediate transfer and steer by the moon, and steer by the moon and return. The characteristics of transfer time and velocity increment of the three emergent return methods were studied. The advantages and disadvantages of the three emergency return methods were analyzed, providing reference for translunar trajectory selection in subsequent human lunar exploration missions.
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    Dynamic analysis of liquid sloshing in spherical tank based on SPH method
    MA Junxiao, MA Liang, WEI Cheng, HU Yue, ZHAO Yang
    2020, 40 (1):  7.  doi: 10.16708/j.cnki.1000-758X.2020.0002
    Abstract ( 24 )   PDF (10035KB) ( 17 )   Save
    For the problem of spacecraft spherical tank sloshing with large probability of liquid fracture, the smoothed particle hydrodynamics (SPH) method was selected for modeling analysis. The NS equations were discretely approximated, and the kernel function, stress tensor, boundary problem, neighborhood particle search were selected respectively. The calculation process finally leads to a fluid dynamics model based on the SPH method. By establishing the simulation model of different fuel liquid volumes and baffle mounting positions, the force and local pressure of spacecraft spherical tank were analyzed by simulation. By recording the force and setting the pressure of the measuring point, the influence of different simulation parameters was analyzed and the corresponding laws were finally obtained. The result can provide the technical basis for the design of spacecraft spherical tank.
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    Carrier loop for high dynamic and weak signal in deep space#br#
    QI Hangtian, ZHANG Xiaolin, ZHU Lijin
    2020, 40 (1):  19.  doi: 10.16708/j.cnki.1000-758X.2020.0003
    Abstract ( 23 )   PDF (3589KB) ( 5 )   Save
     High dynamic and weak signal carrier tracking methods in deep space communication was analyzed. The nonlinear selection problem of state equation and measurement equation in carrier tracking was proposed. The determinants in high dynamic weak signal tracking were discussed and two inferences were given. Based on Kalman filter, phaselocked loop (FLL) and unscented Kalman filter(UKF) were used to assist in different environments. Aiming at the frequency step problem in the combination tracking loop state transition,  the mathematical expression of the working mode and switching threshold of the novel loop were presented. Calculation discriminator in the loop controls the loop output and at the same time eliminates the wild value. The simulation shows that the loop algorithm has good low signaltonoise and highdynamic adaptability compared with the existing algorithms.
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    Control method and fuel consumption analysis on random relative stationkeeping in close range to space debris
    WANG Haoyu, HOU Xiaogeng
    2020, 40 (1):  27.  doi: 10.16708/j.cnki.1000-758X.2020.0004
    Abstract ( 30 )   PDF (3718KB) ( 23 )   Save
    The problems of control method and fuel consumption in random relative stationkeeping in close range to a space debris were investigated. Based on CW equations, control model was established in closerange stationkeeping on a random relative fixed point. The statefeedback controller was designed. The controllability and thrust requirement was studied. Results show that two orthogonal constant forces relating to position of the fixed point, and three orthogonal forces along three axes of the orbital frame to counteract to the perturbation, are required in closerange stationkeeping. Then the basic configuration scheme of satellite subsystem for stationkeeping control was proposed and discussed. The analytical models for fuel consumption and fuelconsumption rate were established. Finally, the minimum fuel consumption model was analyzed in closerange hovering with safedistance demand and relativeorientation demand being satisfied.
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    Numerical research on heat transfer characteristics of regolith thermal energy reservoir based on spherical stacking
    LI Mengmeng, HU Dinghua, LI Qiang
    2020, 40 (1):  37.  doi: 10.16708/j.cnki.1000-758X.2020.0005
    Abstract ( 33 )   PDF (4024KB) ( 7 )   Save
    Regolith thermal energy reservoir is an important way of insitu resource utilization on the moon, and is also a potential method to solve the energy demand of future lunar base construction. A porous medium model of regolith thermal energy reservoir based on spherical stacking was established to simulate the flow and heat transfer process numerically. The shell of the thermal energy reservoir is a fuel tank of descent module, and the helium is used as the working heat transfer medium. Numerical study was carried out to investigate the effects of the stacking mode and diameter of regolith balls on the heat transfer process of the thermal energy reservoir under different flow pressure drop, and the dynamic process of the thermal energy reservoir was analyzed. The results show that the coefficient of heat storage performance (CHSP) of the simple cubes(SC) model is 302% higher than that of the face centered cubes(FCC) model. It is also found that there is an optimal diameter of the regolith ball, which can make the thermal energy reservoir obtain the maximum heat storage under the unit pump power, and the optimal value decreases with the increase of inlet and outlet pressure difference of the fluid. This study can provide theoretical basis and guidance for the design and optimization of regolith thermal energy reservoir. 
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    Thermal characteristics optimization of hollow cathode
    YU Bo, SONG Na, KANG Xiaolu
    2020, 40 (1):  45.  doi: 10.16708/j.cnki.1000-758X.2020.0006
    Abstract ( 104 )   PDF (4056KB) ( 158 )   Save
     The hollow cathode commonly serves as an electron source in ion or Hall propulsion systems, and its thermal characteristics exert a great impact on the cathode’s performance and life time. In order to study the temperature distribution and heat consumption power of the operating hollow cathode, a numerical analysis was conducted. The cathode temperature distribution in steady state was solved by combining the fluid calculation (F process) and the heat transfer calculation (HT process), in which both the F process and the HT process provided the input conditions to each other and iterated over again. A temperature measurement test was performed to justify the model’s accuracy. Five measurement points were set on the cathode surface, and the temperatures solved by the calculation were compared with test results. The maximum calculation error is less than 5%, based on which the thermal characteristics were modeled with different cathode structures and materials. The results show that the heat consumption power presents a trend of firstdecreasethenincrease with the cathode changing from a shorter length to a longer one; the heat consumption power increases and the temperature decreases when higher emissivity keeper shell is adopted.
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    Feasibility analysis of airbreathing plasma propulsion system
    YANG Zhaolun, GUO Ning, CHEN Xuekang, YAN Nengwen, WANG Cong
    2020, 40 (1):  54.  doi: 10.16708/j.cnki.1000-758X.2020.0007
    Abstract ( 143 )   PDF (1591KB) ( 128 )   Save
    The airbreathing plasma propulsion system has been studied as a potential technology for longlife super low altitude flight. According to different orbital environmental conditions, the feasibility of the airbreathing plasma propulsion system was discussed by using the tubular inlet and the mechanical pressurization suction method. The analysis shows that the ratio of the total power required by the spacecraft to the windward surface should be greater than 2kW/m2, and that the specific impulse of the plasma thruster should be greater than 4×104m/s, so as to meet the requirements of pushdrag balance. It is pointed out that in order to realize the application of suction system in earth orbit, the key technology is to increase gas collection efficiency and reduce collection power consumption, while the efficiency of plasma thruster needs to be further improved.
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    Task scheduling of lunar relay satellites for minimal data loss
    WANG Luqi, LIU Bingyi, GUO Wei, ZHU Weige
    2020, 40 (1):  60.  doi: 10.16708/j.cnki.1000-758X.2020.0008
    Abstract ( 16 )   PDF (3470KB) ( 5 )   Save
    The probes on the back of the moon must rely on lunar relay satellite for communication. Lunar relay tasks include realtime tasks such as telecontrol and telemetry, and delaytolerant tasks such as data transmission tasks. When the amount of data that the probe is waiting to transmit exceeds the probe′s storage capacity, the delaytolerant task may fail due to the insufficient local storage resources and the limited communication links of relay satellite, which will cause data loss. Therefore, it is necessary to design a reasonable lunar relay task scheduling strategy to improve the resource utilization of lunar relay satellite and reduce data loss.  The task scheduling of lunar relay satellite problem was investigated. A lunar relay satellite task scheduling model was established to minimize the data loss and a scheduling algorithm based on discrete firework algorithm (DFWA) was designed to solve this model. Simulation results show that our algorithm performs better than Genetic algorithm (GA) in the terms of data loss.
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    Design and implementation of a space fuelcell power system#br#
    LIU Jian, WAN Cheng’an, GUO Shuai, HE Xiong
    2020, 40 (1):  70.  doi: 10.16708/j.cnki.1000-758X.2020.0009
    Abstract ( 18 )   PDF (3561KB) ( 8 )   Save
    Aiming at the space application and according to the demand of one spacecraft’s power consumption during a task, an architecture of a fuelcell and a storage battery was used to research the design and implementation of a 1kW fuelcell power system. A simulation model of the system used to verify the system’s design principle was built. Also, a prototype of a 1kW fuelcell power system was developed and some tests like the load’s step changing were done on it. The results show that when a step changes with half load, the 1kW fuelcell power system’s variation of the bus voltage is less than 5V and the settling time is less than 25μs; the system works normally and steadily in the whole running process, and it can meet the spacecraft’s space application demand.
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    Study of shielding solution for lunar surface work of Chang’e-4 lander
    YANG Mei, LI Fei, LIU Decheng, ZHAO Yang, ZHANG He, WU Xueying
    2020, 40 (1):  78.  doi: 10.16708/j.cnki.1000-758X.2020.0010
    Abstract ( 15 )   PDF (6602KB) ( 5 )   Save
    The target landing site for Chang’e4 mission is the rugged area of South PoleAitken(SPA) basin,which is located on the farside of the moon. There are many craters densely distributed in the SPA basin, the uneven topography will result in high risk of sunlight and communication shield when the lander works on  lunar surface. Communication and sunlight shield was analyzed. Then, the solution to reduce the lander’s survival risk generated by the shielding was presented in three aspects: to increase the landing precision by optimizing the trajectory control strategy, to optimize the lunar surface operating programme, as well as to add the function of the lander’s autonomus management. The solution has  been used in the Chang’e4 probe successfully, providing reference for future deep space exploration missions.
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    High functional density avionics system for satellites#br#
    ZHAN Panpan, CAO Yating, ZHANG Cuitao, LIN Xiangyu, GU Ming
    2020, 40 (1):  87.  doi: 10.16708/j.cnki.1000-758X.2020.0011
    Abstract ( 23 )   PDF (3752KB) ( 9 )   Save
     The microsatellite avionics system, which carries out most of the functions of the satellite, is the center of satellite mission processing and control. In the future, new intelligent applications, satellite cluster applications, communications services and other requirements will also be implemented by satellite, which puts forward new requirements for avionics system. The typical microsatellite avionics systems abroad were analyzed. It has the characteristics of high function density. Most functions are concentrated in one computer and satellite functions are software defined. The integrated structure of avionics system based on software definition was designed. The hardware was modularized with highly integrated design, and the software was layered and componentized. The functions and services of each layer were realized by means of software definition components. High functional density avionics system is composed of a general high performance hardware platform and various kinds of loadable APP software. In addition to traditional functions, it can also be extended to autonomous mission management, intersatellite networking and payload management functions. Not only the integration and functional density of satellites have been greatly improved, but also the functional reconstruction of satellites has been realized, achieving the goal of multifunctions in one satellite. It can provide reference for future applications of constellation network.
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    Optimization design and realization of GEO satellite onboard computer
    XU Nan, LI Zhaoyang, WANG Zhaoqi, HAN Xiaodong, AN Weiyu, WANG Xiaoyu, FENG Yanjun
    2020, 40 (1):  94.  doi: 10.16708/j.cnki.1000-758X.2020.0012
    Abstract ( 15 )   PDF (1568KB) ( 15 )   Save
     The current design of GEO orbit satellite onboard computer was analyzed, including memory design, data sharing design and bus protocol design. In view of the shortcomings of the above three aspects, a CPU minimum system memory optimization design method was proposed, which solves the memory chip selection problem. A “memory + FPGA circuit” design method was proposed realizing data sharing between nominal and redundancy onboard computer.An adaptive bus protocol design method was proposed which makes the 1553B bus protocol more general. The design method proposed has been applied in the next generation high capability communication satellite onboard computer in China, and promising results have been obtained. It also provides a new way of thinking for the followup optimization design of the onboard computer.
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