Jun 2024, Volume 11 Issue 2
    

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  • Research Progress of Radio Frequency Ion Thruster
    MA Longfei, HE Jianwu, LUO Jun, ZHANG Chu, YANG Chao, FU Jiahao, DUAN Li, KANG Qi
    2024, 11(2): 111-123. https://doi.org/10.15982/j.issn.2096-9287.2024.20230036
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    The principle of radio frequency ion thrusters（RIT），as well as the research history and achievements of micro-newton and milli-Newton RIT at home and abroad in the past 60 years，was explained in detail. The radio frequency ion propulsion system involves a number of key technical challenges. Preliminary solutions to the problems of propellant selection， radio frequency（RF）circuit impedance matching，gas flow control，electrical neutralization control and lifetime were proposed， and the development trend and research direction were put forward combined with the future application of RIT.
  • Research on Long Life Carbon Nanotube Cathodes for Deep Space Exploration Missions
    CHEN Zexuan, XIAO Dongyang, DU Huanhuan, SONG Peiyi
    2024, 11(2): 124-131. https://doi.org/10.15982/j.issn.2096-9287.2024.20230152
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    To meet the demand for long-life carbon nanotube field emission cathode in deep space exploration，the failure mechanism of CNTs cathode was investigated，and a long-life CNTs cathode design was introduced. Patterning the CNTs as an array of CNTs island offers a way to eliminate the shielding effects of electrical field. In this way the areas of emitting CNTs are larger，which avoids over-heating on a small emission area. A bonding technique was introduced，the contact between CNTs and substrate was maintained by molecular forces previously，melting metal was introduced as the bonding layer. The mechanical robustness of the CNTs cathode was enhanced while the electrical/thermal resistance was reduced. Performance tests were conducted on the prototype in a high vacuum environment. The prototype produced a current of 0–1 mA with a resolution less than 2 μA and the noise level was less than 1 μA/Hz1/2@0.01–1 Hz. The prototype was tested by over 550 hours' continuous emitting，showing good stability in long-term use.
  • Analysis and Suppression Methods of High Temperature Problems in the Throat of Orbit Controlled Engine
    LI Jianrui, SU Hang, LIU Changguo, CHEN Hongyu, YE Yixiang
    2024, 11(2): 132-140. https://doi.org/10.15982/j.issn.2096-9287.2024.20230154
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    Based on the phenomenon of single-side local high temperature of throat and high jump of weld temperature during steady-state test ignition of the engine. which seriously endangers the reliability of the engine，CFD simulation was used to model the structure of the head injector and optimize the distribution structure in the flow channel combined with the flow resistance mathematical model. To achieve the reduction of jet flow resistance and improve the non-uniformity of flow caused by impact，and optimize the combustion structure and liquid film cooling scheme in the side zone by adjusting the impact parameters，optimize the mixing ratio in the side zone，and reduce the throat temperature and circumferential temperature difference. The improved engine has been verified by experiments. Under the condition of unchanged performance，the temperature of the high-altitude simulated thermal test throat was reduced from nearly 1 500 ℃ to 1 270 ℃，the temperature at the headbody weld was reduced from 520 ℃ to 310 ℃，and the temperature difference of the engine body was controlled within 50 ℃，which effectively solved the problem of high temperature in the engine throat. The service life and reliability of the engine were improved.
  • Research on Micro Newtonian Electrospray Thruster with Wide Thrust Range
    HUANG Xiaobo, SUO Xiaochen, YANG Fan, WANG Dian, JIA Hongyu, LI Jiahui, ZHANG Wensheng, SONG Peiyi
    2024, 11(2): 141-150. https://doi.org/10.15982/j.issn.2096-9287.2024.20230157
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    In light of the demands for a micro-Newtonian level field emission electric thruster with wide，stable，precise， rapid，and persistent characteristics due to the drag-free control on satellites in space gravity wave detection missions，the mutual limitations between adjustable width range，resolution，and thrust noise should be broken through.Based on the principle of field emission thrust generation，and high-precision single pendulum to calibrate the accuracy of the model was uesd. Based on this thrust model，a flow and voltage-based active regulation strategy was established to control thrust，and a thrust feedback control strategy was proposed to maintain low thrust noise levels in a wider thrust range，accroding to the requirements for thrust control resolution and response speed. Finally，performance characterization was carried out on the developed prototype of the thruster principle，achieving 0.86-83.54 μN level，thrust resolution less than 0.1 μN，<0.1 μN/Hz1/2，thrust noise in the millihertz frequency band less than 0.1 μN and less than 10 ms for thrust response time with constant flow.
  • Operating Characteristics of Carbon Nanotube Neutralizer for Space Exploration Missions
    WANG Yuxin, WU Zhiwen, HUANG Tiankun, WANG Yunbing
    2024, 11(2): 151-158. https://doi.org/10.15982/j.issn.2096-9287.2024.20240004
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    With the development of high-precision space exploration missions such as gravitational wave detection and Earth gravity field detection，the accuracy requirements of propulsion systems are further improved，and it is urgent to develop neutralizers with stable output of small current. In this paper，the working stability and electron extraction of carbon nanotube field emission neutralizer were experimentally studied. The current fluctuation characteristics before and after aging were tested， and spearman rank correlation test was used to analyze the correlation between background electric field and current fluctuation. Besides，three kinds of gate with different aperture were used to test the extraction characteristics of the neutralizer，and the influence mechanism of gate aperture on the performance of the neutralizer was analyzed. The experimental results show that aging treatment is helpful to improve the working stability of the neutralizer，and the background electric field of the emitter has a strong correlation with the instability of the emission current. The gate aperture has influence on both emission and extraction performance，and the 1 mm gate aperture has the best performance under experimental conditions. The results can provide some guidance for neutralizer configuration and structure design in propulsion system.
  • Progress in Lunar Space Weather Detection and Research
    LUO Bingxian, ZHANG Xianguo, SUN Tianran, BAI Xianyong, WEI Fei, LIN Ruilin, LI Lei, ZHANG Shenyi, KONG Linggao, WANG Xinyue, XIE Lianghai, PENG Songwu, TANG Binbin, ZHANG Yingjie, XU Qiuyu, LENG Shuang, FENG Pengyuan, SU Yang, GAN Weiqun, FENG Li, TIAN Hui, CHEN Linjie, YAN Yihua, SONG Yongliang, LIU Siqing, DENG Yuanyong
    2024, 11(2): 159-168. https://doi.org/10.15982/j.issn.2096-9287.2024.20220086
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    The stable celestial geological structure，the suitable distance from the Earth to the Moon，and no dense atmosphere and global magnetic field make the Moon a natural and excellent laboratory for the monitoring and research of the Sun-Earth-Moon space weather. This paper reviews the progress of lunar space weather detection and research，and surveys the key scientific problems of lunar space weather and the problems of its prediction application，proposes the concept of the Moon-based space weather monitoring station，set up the specific scientific objectives of the monitoring station，and finally introduces its three major systems and the relationships among them，including the monitoring system，the scientific research system，and the modeling and forecasting system. The establishment of a Moon-based space weather monitoring station is of great scientific significance for studying the mechanism of solar eruptions，the coupling of the Sun to the Earth and the Moon，and the local variations of the Moon’s environment. It will also promote the development of lunar space weather modeling and prediction technologies and improve the capability in providing space environmental safeguard services for future lunar explorations.
  • Scientific Objectives and Configuration Payloads of Asteroid Defense Test Missions
    ZOU Yongliao, XUE Changbin, JIA Yingzhuo, LI Mingtao, XU Haitao, LYU Bohan, GU Zheng, TANG Yuhua, CHEN Qi, WANG Chi
    2024, 11(2): 169-176. https://doi.org/10.15982/j.issn.2096-9287.2024.20230020
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    As for China’s first near-Earth asteroid defense on-orbit verification mission，the defensive disposal of the potential risk of near-Earth asteroid impact on the Earth was verified. The scientific objectives，scientific exploration mission were put forward，the scientific payload requirements analysis was conducted，scientific payload configuration was proposed. This study may provide a basis for decision-making for the implementation of the future asteroid defense missions .
  • Experiments on Space-Ground Cooperative Monitoring and Precise Orbit Determination of Near-Earth Asteroids
    LIU Jing, CHENG Haowen, YANG Zhitao, LI Dawei, CAO Li, JIANG Hai, LI Yang, WANG Huachao
    2024, 11(2): 177-183. https://doi.org/10.15982/j.issn.2096-9287.2024.20230062
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    Based on the Space Debris Experiment Telescope of the National Astronomical Observatories of the Chinese Academy of Sciences，together with the Yangwang-1 and Jilin-1 satellites，a space-based and ground-based collaborative monitoring experiment for near-Earth asteroids was designed and carried out. By using image processing and orbit determination methods，target detection and astronomical positioning of observation images were realized，and the orbit of near-Earth asteroids was precisely determined. Based on the analysis，the existing equipment can realize space-ground collaborative monitoring and orbit cataloging of near-Earth asteroids，and provide orbital data support for the study and estimating of impact risk of near-Earth asteroids.
  • Layout Analysis and Efficiency Evaluation of Space-Based DRO Monitoring System for Near-Earth Asteroids
    ZHANG Wei, LI RUNDAO, SHI Xiaolian, WU Di, YUAN Yuan, WANG Wei
    2024, 11(2): 184-194. https://doi.org/10.15982/j.issn.2096-9287.2024.20230087
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    To address such the problems as the limitation of the invisible zone of the ground-based monitoring system for near-Earth asteroids and the insufficient discovery and cataloguing capabilities of the monitoring system，a solution of a space-based distant retrograde orbit 4-satellite monitoring system was proposed.Then，the space-based monitoring system's to solve the problems mentioned above was quantified and analyzed，and a cosrreponding model for evaluating the efficiency of the system was set up. A process for the implementation of the corresponding evaluation software was given and an integration of the scoring of various elements was completed in accordance with the visible and infrared spectrum. By analyzing and evaluating，the efficiency of the distant retrograde orbit monitoring layout in compensating for the full-time visibility of the invisible zone of the ground-based monitoring system was verified，as well as the enhancement of the capability of target discovery and cataloguing. This research could provide design reference for subsequent construction of space-based monitoring system.
  • Computational Simulation of the Dynamics of Craters Formed by Asteroid Collisions with Land
    XU Wenjie, LIU Qinqin, SHEN Xuhui
    2024, 11(2): 195-202. https://doi.org/10.15982/j.issn.2096-9287.2024.20230060
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    TheThe process of an asteroid impacting the land is a complex non-linear dynamic process，which is difficult to study by using model tests. Numerical simulation provides an important tool for the analysis of this process. In this study，the large-scale numerical simulation of the dynamic process of the asteroid impacting land was realized initially by using the self-developed software CoSim-DEM based on the discrete element method (DEM). Based on the numerical simulation results，the four stages of the impact process—initial contact，impact excavation, high-speed ejection and adjustment—were simulated；the incidence angle and the dynamic behaviors of the asteroid during the impact process would affect the topographic characteristics of the crater. This study also indicates that large-scale numerical methods can be used to perform the analysis of dynamic process of the asteroid impacting the earth, and provide support for asteroid defense.
  • Experimental Study on Influence of Near-Earth Asteroid Material Characteristics on Laser Ablation Driving Efficiency
    SONG Guangming, REN Siyuan, GONG Zizheng, ZHANG Pinliang, CHEN Chuan, WU Qiang, CAO Yan
    2024, 11(2): 203-210. https://doi.org/10.15982/j.issn.2096-9287.2024.20230109
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    Based on the issues closely related to the laser driving effect and the characteristics of asteroid materials, experimental research was conducted on the ablation driving efficiency of pulsed laser on near Earth asteroid materials. Different materials and porosity of asteroid like test samples were selected to measure the impulse coupling law. The experimental results show that under the action of pulsed laser ablation, C-type asteroids have higher impulse coupling efficiency than S-type asteroids; As the porosity of asteroids increases, the efficiency of impulse coupling decreases, and the efficiency of laser ablation driving decreases. In addition, experiments were conducted on the changes in mass of laser ablated asteroid like materials, and the results showed the existence of a laser power density that maximizes the efficiency of asteroid mass ablation. For threat asteroids that require long-term warning time, reducing their mass at the fastest rate while ablating and deflecting their orbits can further improve defense efficiency and achieve defense objectives.