May 2022, Volume 5 Issue 6
    

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  • The Development Overview and Prospect of Lunar Relay Communication Satellite System
    ZHANG Lihua, WU Weiren
    2018, 5(6): 497-505,568. https://doi.org/10.15982/j.issn.2095-7777.2018.06.001
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    The relay communication is a key problem for lunar exploration missions，especially the landing and cruising on the lunar farside and polar areas，as well as the manned lunar exploration missions. The research and development status are analized about lunar relay communication satellite system throughout the world. Based on the analysis on the requirements for lunar relay communication missions，the implementation approach are analyzed for relay communication system scheme，orbit selections，etc. The technical development trends for future lunar relay communication satellite system are also given in this paper.
  • Research and Analysis for Relay Communication System of Chang’e-4 Lunar Relay Satellite
    XU Jin, ZHANG Aibing, HE Yifeng, YANG Guangwen
    2018, 5(6): 506-514. https://doi.org/10.15982/j.issn.2095-7777.2018.06.002
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    In order to realize the landing mission of Chang’e-4 satellite on the far-side of the Moon，a lunar relay communication satellite is developed to provide relay communication service between the ground station and the lander as well as the rover of Chang’e-4 on the farside of the Moon. The relay communication system is the main payload and the key to accomplish mission objectives of the relay satellite.The technical scheme of the relay communication system is studied and analyzed in this paper.
  • The Mission Analysis and System Design of Chang’e-4 Lunar Relay Communication Satellite
    ZHANG Lihua, XIONG Liang, WANG Peng, SUN Ji, ZHOU Wenyan, GAO Shan, LIU Shi, WANG Xiaolei, GUAN Yifeng, ZHANG Aibing, XU Jin, CHEN Guohui
    2018, 5(6): 515-523. https://doi.org/10.15982/j.issn.2095-7777.2018.06.003
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    The relay communication satellite is an important part of Chinese Chang’e-4（CE-4）Lunar farside exploration mission. The relay communication satellite will provide relay communication support for the lander and the rover on the lunar farside. Different from other spacecraft for lunar mission，a Halo orbit around the Earth-Moon L2 liberation point is used to provide continuous communication links to the lander and the rover on the farside of the Moon. A series of challenges have to be faced. Based on the analysis of the mission characteristics and mission requirements，the technical difficulties are identified and solutions for these problems are given，including selection of mission orbit，arriving and maintenance of the mission orbit，the relay communication design trade-off，etc. The system design overview of the CE-4 relay communication satellite is also given in this paper.
  • Design and Verification for Umbrella-Type Deployable Antenna of Chang’e-4 Lunar Relay Satellite
    CHEN Guohui, HUA Yue, WANG Bo, ZHENG Shikun, XIAO Yong, MA Xiaofei, ZHANG Aibing, CHEN Lan
    2018, 5(6): 524-530. https://doi.org/10.15982/j.issn.2095-7777.2018.06.004
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    The radial rib deployable antenna is the key equipment for the Chang’e-4 lunar relay satellite，which provides relay communication for the Chang’e-4 lander and inspector landing on the back of the moon. In this paper，the design principle and structure of the radial rib deployable antenna are described，and the technical difficulties such as on-orbit deployment，mesh formation and maintenance，and ultra-low temperature environmental adaptability are analyzed. For the In-orbit deployment of antenna，slow-release spring distributed drive deployment technology is adopted，which has the advantages of flexible layout，lightweight，small installation volume and high reliability. Experiments of life and thermal vacuum environment deployment are carried out to verify the correctness of the antenna deployment technology. Double-layer network structure is adopted to realize the formation and maintenance of antenna mesh，and optimize the number of tension mesh nodes. The test and thermal deformation prediction of the antenna on-orbit verify that the accuracy of the antenna on-orbit profile is up to sub-millimeter，It ensures that the antenna on-orbit performance meets the mission requirements. The verification of the ultra-low temperature environment, with the lowest temperature reaching −250℃，show that the performance of the antenna is unvarying under the extreme low temperature，which meets the adaptability of the antenna on-orbit environment. The verification results effectively support the smooth implementation of the relay communication task of Chang’e-4 lunar relay satellite.
  • Preliminary Study on the Orbit Determinationof Chang’e-4 Lunar Relay Satellite Mission
    DUAN Jianfeng, LIU Yong, LI Xie, CHEN Ming, WANG Zhaokui
    2018, 5(6): 531-538. https://doi.org/10.15982/j.issn.2095-7777.2018.06.005
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    The Chang' e-4 mission will explore the back of the moon by the lander，inspector and relay satellites that orbit the second Lagrange point（L2）. The relay satellites have been launched and entered Halo orbit around L2 successfully. Based on the mission orbit dynamics model of the relay satellite，the perturbation source magnitude of the relay satellite in Halo orbit and the main factors affecting the orbit determination and prediction are analyzed by simulation. The results show that the Solar pressure perturbation is the main factor affecting the orbit determination and prediction. In order to reduce the influence and improve the orbit determination accuracy，a method for calculating the equivalent pressure area is proposed based on the cannon-ball model，combined with the operational characteristics in orbit and the characteristics of the structure of the relay satellite. The simulation results show that the orbit determination accuracy of velocity can be improved about one order of magnitude by using the modified cannon-ball model
  • Application of Deep Space VLBI System in Queqiao Mission
    WANG Mei, CHEN Lue, HAN Songtao, LU Weitao, DUAN Jianfeng, REN Tianpeng, LI Li
    2018, 5(6): 539-543. https://doi.org/10.15982/j.issn.2095-7777.2018.06.006
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    In Queqiao mission, the first stage of Chang'e-4 mission，Queqiao mission，Jiamusi and Kashi deep space stations were used to conduct VLBI（Very Long Baseline Inteferometry） observation to the relay satellite. Real-time and post-time high-precision angular measurement results were obtained，which effectively supported the mission implementation. In the mission，the two deep space stations need to complete the TT&C tasks at the same time，so they cannot alternate the radio source and spacecraft observation to calibrate the system error. Based on this system，a long time interval calibration method was adopted to observe the radio source before and after the spacecraft observation. Multiple interferometric measurements were carried out in the lunar transfer section，the Lunar to L2 transfer section and the Halo orbital formation section. The results show that the observation accuracy of the deep space network is about 3ns.
  • Design of Multiple Lunar Probe Collaborative Control Mode for Lunar Farside Exploration Mission
    PENG Deyun, ZOU Xuemei, LI Liang
    2018, 5(6): 544-553. https://doi.org/10.15982/j.issn.2095-7777.2018.06.007
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    The multiple lunar probe collaborative control design scheme of lunar farside exploration mission is introduced in this paper. A relay satellite is necessary to provide the relay communication between the exploration probes and the ground TT&C network. In order to solve the complex confederate control problem among the relay satellite，the lunar lander，the lunar rover and the circumlunar satellites in the mission，the description method of associated objects in the collaborative flight control is proposed，and the concept of control object and uplink router object is defined，the principle determination of the above objects and the principle of TT&C resource distribution among uplink router objects are given，and the nominal planning mode，the teleoperation planning mode and uplink telecommand mode are introduced. The design scheme’s feasibility is verified by CE-4 mission’s space-ground circuit radio joint test and the on-orbit flight of the relay satellite.
  • The Calibration of Deep Space Exploration Spacecraft Antenna Beam Direction
    XIONG Liang, WANG Jinqing, SUN Ji, GUAN Yifeng, LU Bo
    2018, 5(6): 554-560. https://doi.org/10.15982/j.issn.2095-7777.2018.06.008
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    Based on the pointing accuracy requirements of large-caliber antennas equipped with deep-space detectors, a calibration scheme for the in-orbit pointing of deep-space detectors with large-diameter antennas is presented to solve the in-orbit pointing evaluation problem of large-caliber antennas. By analyzing the characteristics and constraints of the spacecraft，combining with the specific situation of the relaying satellite antenna of Chang'e-4，and adopting the method of satellite-Earth cooperative work，this paper presents the calibration scheme of the antenna pointing to the orbit，and the implementation process of the calibration. Finally，it gives the errors in the calibration process. This scheme can be applied to the design of calibration schemes for other large-space antenna large-caliber antennas.
  • Preliminary Research on the Lunar Base Energy System
    REN Depeng, LI Qing, XU Yingqiao
    2018, 5(6): 561-568. https://doi.org/10.15982/j.issn.2095-7777.2018.06.009
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    The establishment of lunar bases is an inevitable trend in the following deep space exploration. Meanwhile，the energy system is a basic condition for keeping a lunar base working well. In this paper，basic requirements of the energy system are determined by combining lunar base energy requirements and lunar environment features. A variety of energy resources are analyzed comparatively，indicating that utilizing solar energy is the main method in the primary stage of the lunar base energy system. The core technology of utilizing solar energy is to store it with high efficiency. Based on the analysis of energy storage technologies，an energy system scheme using thermochemical hydrogen production combining hydrogen and oxygen fuel cells and photovoltaic power generation devices is proposed. The key technologies for the system design are analyzed，which can be referred in the detailed design of the lunar base energy system.
  • Mission Planning Approach Based on Extensible States for Deep Space Probes
    JIN Hao, XU Rui, CUI Pingyuan, ZHU Shengying
    2018, 5(6): 569-574. https://doi.org/10.15982/j.issn.2095-7777.2018.06.010
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    Due to the uncertainty in deep space exploration，mission planning technology is required for deep space probes to realize autonomous control. In view of the complex function and coupling operation constraints of deep space mission planning，the extensible states are defined based on the state knowledge framework. Based on the analysis of involved constraints in mission planning，the extensible state based planning algorithm is proposed. And the designed structure of extensible states is able to prune irrelevant search space，accelerate the searching process and improve the planning efficiency. The comprehensive experiments are carried out and the computational results indicate that our algorithm can reduce nearly half of the planning steps，accelerate the process of problem solving，and improve the efficiency of mission planning
  • Analysis and Comparison of Reliability of Computer Redundancy Architecture in Space
    LI Jie, SHEN Rui
    2018, 5(6): 575-581. https://doi.org/10.15982/j.issn.2095-7777.2018.06.011
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    Applying redundant architecture is an important way to improve and promote the reliability of computer in space. The redundant architecture of space computer can be organized in different forms depending on the combination of software and hardware resources. Recently most comparisons among different redundant architectures in engineering are performed only by rough analysis，not in quantitative way，especially for the relatively complex architectures. In this study，six typical redundant architectures（dual-unit with cold standby，dual-unit with hot standby，TMR，re-configurable TMR，2+1 triple-unit，and quad-unit）are investigated，the Markov chain models are established and the formulas of reliability are deduced respectively. Reliability of the architectures is calculated，analyzed and compared based on a virtual five-year space task. The simulation results indicate that a solution with cold standby resource can obtain higher reliability. Moreover，the ability of a fault unit to recover easily and quickly can greatly improve the system reliability.
  • Analysis of Urine Treatment and Recovery Technology Used in Manned Deep Space Exploration
    ZHU Guorong, XIE Beizhen, LIU Hong
    2018, 5(6): 582-590. https://doi.org/10.15982/j.issn.2095-7777.2018.06.012
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    BLSS (Bioregenerative life support system) is a key technology for humans to conduct deep space exploration activities and realize long-term manned space flight. The urine wastewater treatment and recovery of the occupants is a very important part in the BLSS system. The large amount of water and nutrients contained in urine could be applied for the preparation of the nutrient solution required for plant growth in the system，which can not only ensure the normal growth of plants within the BLSS，but also contribute to the realization of the substances recycling and improvement in the closure of BLSS. The large amount of salt contained in urine would stress the growth of plants，so it is necessary to treat urine wastewater through certain technical means and recover water and nutrients. In the article，we analyzed several urine treatment technologies studied for space station，such as distillation technology，and then based on the needs of nutrients recovery，we discussed several mature and civilian urine treatment and recovery technologies，such as ion-exchange adsorption technology，ammonia stripping technology，and struvite precipitation technology. The prospects for the application of the urine treatment and recovery technologies in BLSS were discussed as well. In the end，based on the actual needs of BLSS，a urine treatment and recovery technology process that is expected to be used in BLSS is proposed.