Oct 2021, Volume 8 Issue 5
    

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  • Topic：Deep Space Extreme Environment Protection and New Materials
    Research Status and Development Trend of Thermal Control Materials in Deep Space Extreme Thermal Environment
    YU Dengyu, QIU Jiawen, XIANG Yanchao
    2021, 8(5): 447-453. https://doi.org/10.15982/j.issn.2096-9287.2021.20210042
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    Extreme environments such as extreme cool environment, extreme hot environment and gaseous environment will be encountered in deep space exploration; these environments pose great difficulties to the design of thermal control subsystem and put forward strict requirements for thermal control material. In view of future deep space exploration missions in China, the typical extreme thermal environment factors and their influences on the design of spacecraft thermal control subsystem were analyzed. The application and main performance of some new thermal control materials were discussed, and these new thermal control materials include high-temperature aerogel composites with maximum operating temperature of 1 200 oC, low density silica aerogel composites with a density lower than 30 kg/m3, transparent polyimide film and solar heat absorbing coating. The development trend for new thermal control materials was analyzed, such as light-weight heat-resistant materials in extreme high temperature environment and high-efficiency heat insulation materials in gaseous environment.
  • Topic：Deep Space Extreme Environment Protection and New Materials
    Study on Environmental Characteristics of Jovian System and Spacecraft Protection Design
    WANG Jianzhao, QIU Jiawen, HUO Zhuoxi
    2021, 8(5): 454-466. https://doi.org/10.15982/j.issn.2096-9287.2021.20210031
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    The Jovian system exploration is an important field of deep space exploration in China for the future. Environments in Jupiter’s system are very complex and the exploration of them is an important scientific goal. Besides that, such rigorous space environment is also a demanding factor for mission design. In this study, the characteristics and research progress of gravity field, magnetic field, atmosphere/exosphere, electromagnetic radiation, high-energy particle radiation, plasma, and meteoroids in Jupiter’s system are analyzed. The gravity field model is an important basis for the design of the orbit and propulsion subsystem and the redundant model needs to be built. Jovian strong magnetic field constraints the design of sensitive electromagnetic equipment in control subsystem. The main sources of electromagnetic radiation in Jupiter’s orbit include solar radiation, Jupiter/Satellite reflection radiation, and Jupiter infrared radiation. The exospheres of Jupiter’s moons are thin but include different kinds of atoms. The flux of plasma and high-energy particles in Jupiter’s orbit is much higher than that in Earth’s orbit. They can produce a variety of radiation effects. Among these the focus of protection is total dose and internal charging. The sources of meteoroids include interplanetary and Jovian system. The risk of surface degradation or breakdown caused by collision between meteoroids and spacecraft should be avoided.
  • Topic：Deep Space Extreme Environment Protection and New Materials
    Research on Ablation Properties of Light Thermal Protection Materials in Deep Space
    LIANG Xin, FANG Zhou, CHENG Lei, LUO Lijuan, HE Zhaohui, WU Yongzhi
    2021, 8(5): 467-471. https://doi.org/10.15982/j.issn.2096-9287.2021.20210038
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    In light of light thermal protection materials’ anti-ablation difficulty in deep space with higher heat flux, the ablation properties of light thermal protection material A enhanced by honeycomb (self-developed with a density of 0.48 g/cm3) was researched by arc-heated wind tunnel test (with a heat density of 6 000 kW/m2). The density change analysis of the material after ablation was done along the depth direction. The thermal stress of material A was calculated and analyzed. Research results show that the carbonization layer is complete after ablation; it can be clearly seen from the micro graph of the carbonization layer that hollow fillers are broken and the resin matrix cannot be seen; the components of the material react with each other and SiC crystal is generated on the surface of material A, which boosts heat consuming in the processing of ablation and improves the carbonization layer strength and retards oxization. The thickness of pyrolysis layer is thin, which shows that the light thermal protection material has excellent insulation performance. The honeycomb structure of material A can effectively reduce the thermal stress of the material. This research has great significance for the reliability assessment of thermal protection materials in deep space exploration.
  • Topic：Deep Space Extreme Environment Protection and New Materials
    Design and Test Verification of Energy Absorption Material in the Soft Landing Gear for Tianwen-1 Mars Probe
    LUO Min, YANG Jianzhong, HAN Fusheng, MAN Jianfeng
    2021, 8(5): 472-477. https://doi.org/10.15982/j.issn.2096-9287.2021.20210044
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    The landing gear is a key component for soft-landing on Mars, which should use high energy-absorption and excellent thermal stability material to absorb the impact energy of Mars probe. The energy absorption pull rods made by directionally solidified twinning-induced plasticity (TWIP) were utilized for the soft landing gears of Mars lander. The mechanical behavior and microstructure evolution of TWIP steel were investigated. The results show that TWIP steel can sustain the high plasticity of 600 MPa ultimate true stress and 72% true strain. The landing dynamic simulation and experiment results of soft-landing gear drop testes demonstrate that that Mars landing system is able to adapt to the complex topography conditions because of the high energy absorption ability of pull rods.
  • Topic：Deep Space Extreme Environment Protection and New Materials
    Performance Analysis and Experimental Study of Tianwen-1 Parachute Material
    HUANG Mingxing, GAO Shuyi, WANG Liwu, WANG Wenqiang, LI Jian
    2021, 8(5): 478-485. https://doi.org/10.15982/j.issn.2096-9287.2021.20210025
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    Parachute is an important way for a Mars rover to decelerate. As the application conditions of Mars parachutes are very different from those of conventional parachutes. In this article, the environmental and mechanical conditions experienced by Tianwen-1 Mars parachute were analyzed, and by combining the successful landings of Mars parachutes abroad and the development of textile materials, the application of Mars parachute materials was introduced. Then, the weight characteristics of the new Mars parachute material and the influence of humidity on the parachute mass were analyzed. Finally, through parachute materials’ mechanical experiments with high and low temperature environments, high-density packaging, and long-term on-orbit storage conditions, the strength change parameters of the Mars parachute material on Tianwen-1 were obtained. The results indicate that the strength of the parachute material can still meet the working requirements of Mars after experiencing various environmental conditions. This article can provide a reference for the design of parachute materials in subsequent deep space explorations.
  • Article
    A Review of Lunar Space Environment Study
    WANG Mingyuan, WANG Mei, PING Jinsong, HAN Songtao
    2021, 8(5): 486-494. https://doi.org/10.15982/j.issn.2096-9287.2021.20200013
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    After more than fifty years lunar exploration, our understanding of the lunar space environment is still superficial. The lunar dusty exosphere research was based on ARTEMIS mission and the lunar atmosphere and dust environment detector which were developed by NASA. Based on the radio experiments of several lunar missions, the existence of lunar ionosphere is determined. The current status and observation of lunar exosphere and ionosphere are introduced in this paper. With the help of the low frequency radio astronomical payloads carried by Chang'E-4 relay satellite and the lander, more of lunar space environment will be uncovered.
  • Article
    A Study of the Orbit Determination Ability and Time-Sharing Acquisition Mode for China’s Deep Space Network VLBI Data
    NIU Dongwen, DUAN Jianfeng, WANG Mei, CHEN Lue, LU Weitao, REN Tianpeng
    2021, 8(5): 495-502. https://doi.org/10.15982/j.issn.2096-9287.2021.20191120001
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    According to the interferometric observation data of Jiamusi deep space station and Kashi deep space station of China deep space network during the mission of Chang'E-4 prober，the orbit determination accuracy of real-time data and post-correction data respectively combined with the USB data is analyzed. The difference between the Earth Moon transfer section and the precise orbit is 100 meters，and the difference between the ring moon section and the precise ephemeris is 10 meters. At the same time，the influences of VLBI data weight setting on the orbit accuracy is analyzed. In view of theChina deep space network in subsequent deep space missions such as Chang’E 5，a time-sharing acquisition mode is proposed to reduce the amount of VLBI data. The influence of this mode on orbit accuracy is analyzed by using the measured VLBI data of Chang’E 4 prober. The results show that the real-time data accuracy of China’s deep space network VLBI data has reached the accuracy of post-correction data，which can support the follow-up deep space exploration tasks in China. At the same time，for 2 to 3 hours per day of common viewing time of two stations，in the time-sharing acquisition mode，the total 20 minutes per day data and 1 minute acquisition step can ensure that the orbit accuracy does not decrease.
  • Article
    Image Compression Software Design for Zhurong Mars Exploration Rover
    ZHU Jianbing, XU Yong, WANG Cuilian, ZHU Ma, CHEN Jiwei, HAN Qinglong
    2021, 8(5): 503-510. https://doi.org/10.15982/j.issn.2096-9287.2021.20210065
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    Because of the limited number of information transmission channels and high bit error rate in Mars image transmission, a method of image compression software design and realization of Mars rover was proposed. The characteristics of rover image data management were analyzed, and the three capabilities that the rover image compression software needed to have were concluded: uniform file management capability, high-efficiency compression capability, and high fault tolerance capability. For uniform file management capability, a file system for uniform management of multiple types of image data was proposed. To meet the high efficiency and high fault tolerance requirements of the compression algorithm, based on run-length coding algorithm of first-1 bit, the three important processes of multi-load image unification processing, color image preprocessing, and segmented bit-plane image coding were expanded, to improve compression performance and fault tolerance. Then a complete set of image compression software design schemes was formed, using FPGA+DSP, and the complete set of software was realized. Finally a simulation verification system was used to verify the compression effect. Verification results show the effectiveness of the algorithm. This software has been verified by China’s Zhurong Mars rover and can effectively meet the needs of Mars exploration missions. The software design can be used as a reference for image compression in subsequent ultra-long-distance deep space explorations.
  • Article
    Variable Coefficient Terminal-Phase Guidance Design for Deep Space High-Speed Impact
    ZHENG Huixin, PENG Yuming, WANG Wei, XIE Pan, LU Xi, LI Haiyang, CHEN Xiao
    2021, 8(5): 511-518. https://doi.org/10.15982/j.issn.2096-9287.2021.20200095
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    Asteroid impact poses a major threat to human survival. High-speed direct impact is a feasible and effective means to change the orbit of an asteroid. This paper takes Bennu, a potentially hazardous asteroid, as an object to design the terminal guidance law of deep space high-speed impact. In view of the characteristics of high relative speed and high impact accuracy, the acceleration command is derived based on the Augmented Proportional Navigation Guidance law (APNG), considering the acceleration of the target. Moreover, the proportional coefficient is designed as a function of the relative distance to meet both the requirements of minimum fuel consumption and maximum impact accuracy. An ignition strategy is designed to convert the continuous command into impulse command, without the need to give maneuvering time in advance. The simulation results show the effectiveness of the proposed algorithm. The miss distance constraint is satisfied, and the ignition times and fuel consumption are less than those of the constant proportional coefficient algorithm.
  • Article
    Mission Planning Based on Dynamic Agent Interaction Graph for Deep Space Probes
    ZHAO Yuting, XU Rui, LI Zhaoyu, ZHU Shengying
    2021, 8(5): 519-527. https://doi.org/10.15982/j.issn.2096-9287.2021.20210020
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    Facing the increasingly complex deep-space exploration missions and the dynamic space environment, deep-space probes need efficient planning methods for the fast generation of plans. The distribution and concurrency of subsystems make a probe suitable to be modeled as a multi-agent system. Existing multi-agent planners, however, cannot be used directly in mission planning of deep space probes that involve handling numeric constraints such as time resources. To solve the above problem, a multi-agent mission plan-space planning method based on distributed refinement search was proposed. A dynamic agent interaction graph (DAIG) was designed to coordinate interactions between agents during planning. Temporal constraints and resource constraints were modeled as constraint satisfaction problems and were handled by graph theory methods. Experiments show that the method proposed in this paper can save computing time of mission planning problems for a probe with multiple subsystems.
  • Article
    Analytical Initialization for Low-thrust Trajectory Optimization Based on Switching System
    WU Di, CHENG Lin, WANG Wei, LI Junfeng
    2021, 8(5): 528-533. https://doi.org/10.15982/j.issn.2096-9287.2021.20200090
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    The traditional homotopy method usually transforms the low-thrust fuel-optimal control problem into the energy-optimal problem to increase the convergence rate of the indirect method. However, it is still necessary to guess the initial values of the co-states to initialize the solving algorithm. In this paper, the optimization model of the fuel-optimal problem is embedded in the switching system with the analytical initial co-states, which further improves the convergence rate with the analytical initialization. Firstly, the switching system is introduced with the embedded fuel-optimal problem. The switching function of the conventional switching system is derived from the optimal control, but in this paper, the given switching function is designed artificially to realize the switching and continuation among different systems. Secondly, based on the linearization technique, the target system is designed with analytical initial co-states, initializing the solving algorithm by a simple nominal trajectory. Finally, the numerical simulation verifies the effectiveness of the proposed method, which is more efficient than the traditional homotopy method.
  • Article
    A Point Cloud Fusion Method for Space Target 3D Laser Point Cloud and Visible Light Image Reconstruction Method
    SU Yu, ZHANG Zexu, YUAN Mengmeng, XU Tianlai, DENG Hanzhi, WANG Jing
    2021, 8(5): 534-540. https://doi.org/10.15982/j.issn.2096-9287.2021.20210037
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    In this paper, a high-precision spatial target lidar for 3D reconstruction of point cloud and visible light image 3D reconstruction point cloud fusion method is proposed. This fusion method uses the solved 3D reconstruction to invert the camera pose and 3D point cloud model centroid position optimization initial value selection. The registration accuracy and registration efficiency of the ICP algorithm are improved. At the same time, according to the characteristics of the two sets of point clouds, the Euclidean distance threshold is used to delete the noise points of the 3D point cloud edge, and the high-precision 3D reconstruction point with the scale information fusion is obtained. The simulation experiment of the spatial target simulation model shows that the fusion method can effectively improve the point cloud density, fill the reconstruction vulnerability, and improve the point cloud accuracy of the spatial target 3D reconstruction.