Oct 2023, Volume 10 Issue 4
    

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  • Special Issue：Monitoring of and Desense Against Near-Earth Asteroids
    Research Progress in Asteroid Defense On-Orbit Disposal Technology
    WU Weiren, TANG Yuhua, LI Mingtao
    2023, 10(4): 345-356. https://doi.org/10.15982/j.issn.2096-9287.2023.20230111
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    Near-Earth asteroid impact is a major catastrophic threat facing human society. Planetary defense is an inevitable requirement for building a community with a shared future for mankind and continuing human civilization. Implementing on-orbit disposal is the best way to prevent and resolve the risk of near-Earth asteroid impact. This paper systematically combed the development status of near-Earth asteroid defense on-orbit disposal technologies，comprehensively summarized the key technologies，advantages and disadvantages，and application scenarios of nuclear explosion，kinetic impact，gravitational traction，ion beam，laser ablation，tug，mass driver，surface spraying and other on-orbit disposal technologies，and puts forward suggestions for the development of near-Earth asteroid defense on-orbit disposal technology.
  • Special Issue：Monitoring of and Desense Against Near-Earth Asteroids
    Computation Methods for Impact Probability of Near-Earth Asteroids
    LI Xinran, ZHAO Haibin, TANG Yuhua, YU Xishuang, WANG Xiuhai, LI Bin
    2023, 10(4): 357-368. https://doi.org/10.15982/j.issn.2096-9287.2023.20230077
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    Risk assessment, monitoring and warning of near-Earth asteroids (NEA) have become a research hotspot, and impact probability is a key factor in assessing the threat of NEAs. In this paper, the research and development process of NEA impact probability was reviewed, the theoretical framework of impact probability computation and the main tool target plane for research were introduced, the main linear and nonlinear impact probability methods at present were sorted out. At the same time, the research on the improvement and perfection of the impact probability method in terms of computational efficiency and completeness under special circumstances such as too short arcs and non-gravitational effects in recent years was introduced. Finally, key issues and future development trends of this research direction are presented.
  • Special Issue：Monitoring of and Desense Against Near-Earth Asteroids
    Grading Method for Impact Risk of Near-Earth Asteroids
    JIN Yan, LIANG Zixuan, YANG Datao, LI Mingtao, TANG Menghui, ZHAO Haibin, SONG Zhengji, SHI Fangyuan
    2023, 10(4): 369-377. https://doi.org/10.15982/j.issn.2096-9287.2023.20230092
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    Research on the grading of impact risk is an important prerequisite to dealing with the danger of impacts by near-asteroids. In this paper，a new risk-grading method was proposed to estimate the risk of near-Earth asteroid impact. The hazard forms and consequences of near-Earth asteroid impact were analyzed，and the factors of impact risk classification were sorted out. The relatively mature Torino scale model and Palermo index model were discussed，and the equivalent diameter and impact probability were taken as the main factors to design the impact risk grading method. A refinement of partition model of risk grade was established. Finally，the simulation comparison and analysis were carried out for different risk grading models.
  • Special Issue：Monitoring of and Desense Against Near-Earth Asteroids
    Analysis of the Efficacy of Cooperative Space-Based and Ground-Based Observations of Near-Earth Asteroids Based on Solar-Terrestrial L1 Point of the Space-Based Observing System
    FENG Siliang, YU Zhitong, HU Xinran, TIAN Kunhong, LI Bin, DU Fei, SONG Zhengji, SHANG Haibin, LIU Zhimin
    2023, 10(4): 378-386. https://doi.org/10.15982/j.issn.2096-9287.2023.20230085
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    Space-based monitoring and early warning of Near-Earth Asteroids (NEAs) is an important development direction for future planetary defense. Cooperative space-and ground-based observations can give full play to the advantages of space- and ground-based telescopes and improve the efficacy of the system as a whole. In this paper，a model of near-Earth asteroid observation was formulated，a scheme of space-based observation system for Sun-Earth L1 point orbit was analyzed and designed，and an efficacy evaluation method was proposed. The cooperative observation efficacy of the Sun-Earth L1 point orbit observation system was simulated and evaluated based on the potentially hazardous asteroids database. The relevant early warning efficacy was calculated and analyzed，and the design concept of regional and time-domain divided collaborative observation was proposed. This paper provides importance reference for future evaluation of the efficacy of different space-based observation systems and the study of space- and ground-based cooperative observations. The preliminary simulation results show that the infrared and visible systems of the Sun-Earth L1 point orbit can achieve 49.4% and 38.2% cataloging completeness of the potentially hazardous asteroids in 1 year with a limited apparent visual magnitude of 22，and both can carry out the monitoring mission well；after cooperative observation with ground-based station，the completeness rate of the corresponding cooperative system can reach 58.9% and 50.6%，respectively， which is 1.19 times and 1.35 times that of the completeness rate before，indicating that cooperative observation can effectively improve the observation efficacy of the system.
  • Special Issue：Monitoring of and Desense Against Near-Earth Asteroids
    Analysis and Design of Asteroid Impact Defense Mission
    ZHANG He, GU Zheng, HAN Chengzhi
    2023, 10(4): 387-396. https://doi.org/10.15982/j.issn.2096-9287.2023.20230025
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    To deal with the risk of high-risk near-Earth asteroid impacts on Earth，in this article，a detailed mission analysis of impact defense was conducted. Based on this，an “observation + impact + evaluation” asteroid impact defense mission plan was proposed，which solves the problem of existing plans relying on ground-based observation and being difficult to accurately evaluate. Kinetic energy impact and comprehensive and accurate efficiency evaluation can be achieved through a single mission. This paper can provide reference for asteroid exploration missions
  • Special Issue：Monitoring of and Desense Against Near-Earth Asteroids
    Asteroid Recognition of Dim Targets Based on Image Registration
    ZHENG Yuyun, HUANG Xiangyu, MAO Xiaoyan
    2023, 10(4): 397-404. https://doi.org/10.15982/j.issn.2096-9287.2023.20230093
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    In order to meet the autonomous navigation requirements of asteroid approaching impact mission，a method of dim target asteroid recognition based on image registration was proposed. Due to the small size and weak brightness (usually above 10 magnitude) of asteroids, navigation sensors were required to have the ability to image dim targets. This caused the navigation sensor to simultaneously capture a large number of unknown dim stars，posing a challenge to the accurate identification of the target asteroid. The paper utilized the relative motion of asteroids and background stars. Firstly，a combination of ORB feature point localization and BEBLID feature point description was used to register inter-frame images. Secondly，star points were identified based on threshold segmentation，and the structural similarity index between corresponding windows was calculated for each star point. Finally，the detection of dim target asteroids was completed. Compared with the traditional image registration method and target asteroid detection methods，this method has improved speed and accuracy，has overcome the problems of dim target asteroid and unknown background stars，and provides such information as sight vector for optical autonomous navigation of asteroid defense.
  • Special Issue：Monitoring of and Desense Against Near-Earth Asteroids
    Research on Autonomous Guidance Navigation and Control Methods for Small Body Impact Detection
    LIU Jing, ZHU Shengying, TANG Yuhua, XU Rui
    2023, 10(4): 405-412. https://doi.org/10.15982/j.issn.2096-9287.2023.20230110
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    Based on the working mode of the autonomous navigation guidance and control system of the impactor，the autonomous optical information processing algorithm，autonomous optical navigation algorithm and trajectory correction guidance law were designed. Based on the research work of autonomous navigation guidance and control system，a comprehensive test system of autonomous navigation guidance and control for small body impact detection was built. Semi-physical ground simulation test of autonomous navigation guidance and control for small body impact was carried out. The simulation results show that the proposed method can effectively achieve high precision asteroid impact.
  • Special Issue：Monitoring of and Desense Against Near-Earth Asteroids
    Study on Strategy and Efficiency of Dynamic Push Away from Orbit for Near-Earth Asteroids
    XUE Luyao, PENG Yuming, DUAN Xiaowen, HUANG Fan, ZHANG Heng, YUAN Yuan
    2023, 10(4): 413-419. https://doi.org/10.15982/j.issn.2096-9287.2023.20230100
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    In view of the threat of more frequent near-Earth asteroid impacts，the asteroid dynamic push away deflection disposal mission was demonstrated. The disposal method was pushed away the asteroid multiple times by penetrating and anchoring the asteroid surface and by electric propulsion. In this paper，a dynamic model of near-Earth asteroids was established to study the change of orbit deviation of asteroids with different rotation states under the dynamic push away treatment strategy. Taking the deflection of 2019VL5 asteroid as an example，the efficiency of dynamic push away disposal and the feasibility of the project were evaluated by numerical simulation. The simulation results show that during the warning time of 4 years the maximum deflection distance of the asteroid could be 2.91 × 104 km under the small 0.4 N thrust applied to the specific orbital position，and the maximum deflection distance of the asteroid could be 9.0 × 104 km after 2 500 days of disposal. The dynamic push away disposal of asteroids can effectively deflect threatening asteroids，and can be used in future asteroids deflecting defense missions and orbit transfer missions against other space object attacks.
  • Special Issue：Monitoring of and Desense Against Near-Earth Asteroids
    Momentum Transfer Law of Hypervelocity Kinetic Impacting Dense Asteroids
    LIU Wenjin, ZHANG Qingming, LONG Renrong, GONG Zizheng, REN Jiankang, REN Siyuan, WU Qiang, Song Guangming, CHEN Chuan, ZHANG Pinliang
    2023, 10(4): 420-427. https://doi.org/10.15982/j.issn.2096-9287.2023.20230042
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    Kinetic impact is considered an effective way to deflect potentially hazardous asteroids from a collision with Earth. To study the effect of impact velocity on the momentum transfer coefficient，6 mm aluminum projectile was used to impact the basalt target at 2-4 km/s. By comparing the computation results of aluminum sphere impact on basalt with the experimental results，the correctness of the calculation and the statistical method of momentum transfer coefficient was verified. The simulation results show that the mass and velocity distributions of projectiles at different impact velocities were almost the same. The greater the impact velocity，the greater the cumulative mass of projectiles. Combing with the experimental and numerical simulation results，the momentum transfer coefficient similarity law of kinetic impacting asteroids was obtained. The momentum enhancement coefficient of the dense asteroid increases with the increased of the impact velocity to the power of 0.65. The momentum transfer similarity law can provide data support for the kinetic impact deflection of asteroids.
  • Special Issue：Monitoring of and Desense Against Near-Earth Asteroids
    Research on Characteristics of Hypervelocity Impact-Induced Ejecta in Rubble-Pile Targets
    ZHANG Hongyu, CHI Runqiang, SUN Miao, WANG Han, PANG Baojun, ZHANG He
    2023, 10(4): 428-435. https://doi.org/10.15982/j.issn.2096-9287.2023.20230021
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    Kinetic impact deflection is a highly feasible and mature technique in the field of asteroid defense, and has been successfully implemented in related deep space exploration missions. However, a critical issue associated with this technology pertains to the optimization of momentum transfer during the impact process, as well as the evaluation of impact efficacy through analysis of ejecta observation data, for a diverse range of asteroid types. In this study, a target model composed of rubble-piles, constructed with varying proportions of boulder size and mass ratio, was developed and subsequently subjected to numerical simulations of hypervelocity impact of aluminum impactors. The impact of boulder size and mass proportion on the morphology of the ejecta was investigated, and the underlying mechanisms governing these effects were elucidated. The results of the investigation demonstrated that asymmetrical ejecta morphologies were produced as a result of the hypervelocity impact of aluminum impactors on rubble-pile targets, with ray-like ejecta emerging in the gaps between the boulders. The ray part of the ejecta has a larger eject angle, and the ray length and quantity are related to boulder diameter and mass ratio. Based on the rubble-pile target model established in this study, it was found that the maximum momentum of the ejecta produced in the opposite direction of the impact velocity was generated by large-diameter boulder targets. This paper can provide valuable reference for the selection of impact zones in future kinetic impact deflection missions.
  • Special Issue：Monitoring of and Desense Against Near-Earth Asteroids
    Analysis of Ablation Mechanism of Iron Asteroid Materials Under the Condition of Arc Heater Test
    SHI Weibo, DANG Leining, LUO Yue, SUN Haihao, HUANG Jie
    2023, 10(4): 436-442. https://doi.org/10.15982/j.issn.2096-9287.2023.20230029
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    When the asteroid enters earth’s atmosphere at a very high speed，the surface temperature rises and the surface material melts and loses under the severe aerodynamic heat. Studying the ablation mechanism of iron asteroids entering the Earth’s atmosphere is of great significance to study the ablation mechanism of iron asteroids entering the Earth’s atmosphere to evaluate the impact of such asteroids on the earth. In 2021，the Hypervelocity Aerodynamics Institute of China Aerodynamics Research and Development Center carried out the ablation test of the spherical cone-shaped iron meteorite model（head radius 20 mm，half cone angle 9 degrees）on the arc heater. The tested simulated state is that the stagnation heat flux is 13.9~19.5 MW/m2 and the stagnation pressure is 0.51~0.28 MPa. In this paper，based on the experimental phenomenon，the melting ablation model and the melting layer shear ablation model of iron asteroid material ablation are established. and the ablation test state of meteorite model is calculated by using the coupled solution methodology of aerodynamic heat，ablation and internal heat conduction with moving boundary. The calculation and analysis show that the shear ablation model established in this paper can obtain qualitatively consistent stagnation point ablation rate. If the loss of liquid layer is not considered，the calculated law is contrary to the experiment. The calculation shows that the surface evaporation rate is small compared with the mass loss rate of molten layer，which indicates that the ablation of iron asteroids is dominated by the shear loss of molten layer. It can provide reference for asteroid impact Earth defense.
  • Special Issue：Monitoring of and Desense Against Near-Earth Asteroids
    Analysis of and Inspiration from Planetary Defense Exercises
    LI Haitao, XIN Xiaosheng
    2023, 10(4): 443-452. https://doi.org/10.15982/j.issn.2096-9287.2023.20230059
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    The research, technology validation and exercises of planetary defense have become a hot topic and real concern for the international community. General introduction to the international planetary defense exercises (PDE) mainly organized by the United States has been given with a focus on the recent representative 2019 PDE and 2021 PDE. Comparative analysis has been carried out about the exercise participants，scenarios，procedures，and results. Discussions on the related aspects and requirements of planetary defense, such as monitoring and warning，impact risk assessment and active defense strategy， have also been performed. Inspiration and recommendations for Chinese planetary defense actions and related exercises have been proposed.