Implementing the flyby to Near-Earth Asteroids (NEAs) with the potential impact risks to the Earth allows for obtaining detailed physical parameters, thereby supporting the high-precision orbit prediction and planetar...Implementing the flyby to Near-Earth Asteroids (NEAs) with the potential impact risks to the Earth allows for obtaining detailed physical parameters, thereby supporting the high-precision orbit prediction and planetary defense strategy. Different from those conducted asteroid flyby missions, in the 12th China Trajectory Optimization Competition (CTOC-12), a NEAs flyby trajectory design problem using reusable probes that depart from a Lunar Distant Retrograde Orbit (DRO) station in the cislunar space was released. The objective was flyby to as many NEAs as possible using up to 20 probes within a total of 10 years. The ∑ team proposed a solution that can explore 47 NEAs using 11 probes, ranking the first in the competition. In this paper, the methods and results from the winning team are introduced, including mission analysis and preliminary design, and low-energy transfer trajectory optimization. In particular, a round-trip trajectory is divided into three phases: deep space transfer, indirect transfer between the Earth to DRO, and DRO phasing and rendezvous. With the combination of global optimization and local optimization algorithms, the required velocity increments to change the orbital planes are effectively reduced, thus increasing the number of the explored NEAs. The final solution of our team is presented and the results are compared with those of the top three teams. The competition demonstrates that the regularization of flyby missions from the cislunar space to explore NEAs with the potential impact risks to the Earth is the feasible and promising.展开更多
Space laser communication(SLC)is an emerging technology to support high-throughput data transmissions in space networks.In this paper,to guarantee the reliability of high-speed SLC links,we aim at practical implementa...Space laser communication(SLC)is an emerging technology to support high-throughput data transmissions in space networks.In this paper,to guarantee the reliability of high-speed SLC links,we aim at practical implementation of low-density paritycheck(LDPC)decoding under resource-restricted space platforms.Particularly,due to the supply restriction and cost issues of high-speed on-board devices such as analog-to-digital converters(ADCs),the input of LDPC decoding will be usually constrained by hard-decision channel output.To tackle this challenge,density-evolution-based theoretical analysis is firstly performed to identify the cause of performance degradation in the conventional binaryinitialized iterative decoding(BIID)algorithm.Then,a computation-efficient decoding algorithm named multiary-initialized iterative decoding with early termination(MIID-ET)is proposed,which improves the error-correcting performance and computation efficiency by using a reliability-based initialization method and a threshold-based decoding termination rule.Finally,numerical simulations are conducted on example codes of rates 7/8 and 1/2 to evaluate the performance of different LDPC decoding algorithms,where the proposed MIID-ET outperforms the BIID with a coding gain of 0.38 dB and variable node calculation saving of 37%.With this advantage,the proposed MIID-ET can notably reduce LDPC decoder’s hardware implementation complexity under the same bit error rate performance,which successfully doubles the total throughput to 10 Gbps on a single-chip FPGA.展开更多
The energetic particle detector on China's space station can determine the energy, flux, and direction of medium-and highenergy protons, electrons, heavy ions, and neutrons within the path of the station's orb...The energetic particle detector on China's space station can determine the energy, flux, and direction of medium-and highenergy protons, electrons, heavy ions, and neutrons within the path of the station's orbit. It also assesses the linear energy transfer(LET)spectra and radiation dose rates generated by these particles. Neutron detection is a significant component of this work, utilizing a new type of Cs_(2)LiYCl_(6): Ce scintillator material along with plastic scintillators as sensors. In-orbit testing has demonstrated the efficient identification of space neutrons and gamma rays(n/γ). This data plays a crucial role in supporting manned space engineering, scientific research, and other related fields.展开更多
基于Web of Science核心合集数据库,采用文献计量学方法对中国探月工程(2003-2024)的科研产出进行系统分析.通过量化评估1023篇SCI论文的时空分布特征、国际合作态势及学术影响力,揭示了中国探月工程对全球月球科学研究的贡献.研究表明...基于Web of Science核心合集数据库,采用文献计量学方法对中国探月工程(2003-2024)的科研产出进行系统分析.通过量化评估1023篇SCI论文的时空分布特征、国际合作态势及学术影响力,揭示了中国探月工程对全球月球科学研究的贡献.研究表明,中国探月工程的实施使中国月球科学领域发文量占比提升至32.6%(2024年),工程产出论文的CNCI值(1.03)超越全球均值;科研突破集中于嫦娥四号(月球背面着陆巡视探测)与嫦娥五号(月球样品分析)任务,产出181篇高影响力论文;国际引用情况中,非中国机构占比显著增长,显示工程成果获得广泛国际认可.研究成果为评估中国深空探测计划的科学效益提供了定量依据.展开更多
频率资源是支撑航天行业发展的核心战略资源之一,随着作为国际热点的月球开发利用逐渐朝着规模化方向发展,频率资源的需求愈发迫切.然而,在现有国际规则框架下,可提供给月球规模化开发利用的频率资源非常有限,供需矛盾日益加剧.本文围...频率资源是支撑航天行业发展的核心战略资源之一,随着作为国际热点的月球开发利用逐渐朝着规模化方向发展,频率资源的需求愈发迫切.然而,在现有国际规则框架下,可提供给月球规模化开发利用的频率资源非常有限,供需矛盾日益加剧.本文围绕国际地月空间频率资源申请现状、工程任务规划与实施情况开展系统性数据分析,研究当前地月空间频率资源与SFCG(Space Frequency Coordination Group)月球区域频率划分建议的符合度,分析地月空间频率资源的利用态势,同时,利用自主开发的频率兼容性仿真平台,对国际上的典型任务进行了定量化干扰计算分析,提出了后续地月空间探测、开发利用等领域的用频建议,为相关工程任务的规范有序实施提供参考.展开更多
基金supported by the Special Funding Project for Space Debris and Near-Earth Asteroids Defense Research, China (No. KJSP2023020303)Beijing Municipal Science and Technology Commission, China (No. Z181100002918004)the Youth Innovation Promotion Association, Chinese Academy of Sciences (No. 2022146)
文摘Implementing the flyby to Near-Earth Asteroids (NEAs) with the potential impact risks to the Earth allows for obtaining detailed physical parameters, thereby supporting the high-precision orbit prediction and planetary defense strategy. Different from those conducted asteroid flyby missions, in the 12th China Trajectory Optimization Competition (CTOC-12), a NEAs flyby trajectory design problem using reusable probes that depart from a Lunar Distant Retrograde Orbit (DRO) station in the cislunar space was released. The objective was flyby to as many NEAs as possible using up to 20 probes within a total of 10 years. The ∑ team proposed a solution that can explore 47 NEAs using 11 probes, ranking the first in the competition. In this paper, the methods and results from the winning team are introduced, including mission analysis and preliminary design, and low-energy transfer trajectory optimization. In particular, a round-trip trajectory is divided into three phases: deep space transfer, indirect transfer between the Earth to DRO, and DRO phasing and rendezvous. With the combination of global optimization and local optimization algorithms, the required velocity increments to change the orbital planes are effectively reduced, thus increasing the number of the explored NEAs. The final solution of our team is presented and the results are compared with those of the top three teams. The competition demonstrates that the regularization of flyby missions from the cislunar space to explore NEAs with the potential impact risks to the Earth is the feasible and promising.
基金supported by the National Key R&D Program of China(Grant No.2022YFA1005000)the National Natural Science Foundation of China(Grant No.62101308 and 62025110).
文摘Space laser communication(SLC)is an emerging technology to support high-throughput data transmissions in space networks.In this paper,to guarantee the reliability of high-speed SLC links,we aim at practical implementation of low-density paritycheck(LDPC)decoding under resource-restricted space platforms.Particularly,due to the supply restriction and cost issues of high-speed on-board devices such as analog-to-digital converters(ADCs),the input of LDPC decoding will be usually constrained by hard-decision channel output.To tackle this challenge,density-evolution-based theoretical analysis is firstly performed to identify the cause of performance degradation in the conventional binaryinitialized iterative decoding(BIID)algorithm.Then,a computation-efficient decoding algorithm named multiary-initialized iterative decoding with early termination(MIID-ET)is proposed,which improves the error-correcting performance and computation efficiency by using a reliability-based initialization method and a threshold-based decoding termination rule.Finally,numerical simulations are conducted on example codes of rates 7/8 and 1/2 to evaluate the performance of different LDPC decoding algorithms,where the proposed MIID-ET outperforms the BIID with a coding gain of 0.38 dB and variable node calculation saving of 37%.With this advantage,the proposed MIID-ET can notably reduce LDPC decoder’s hardware implementation complexity under the same bit error rate performance,which successfully doubles the total throughput to 10 Gbps on a single-chip FPGA.
基金This mission was supported by the China Manned Space Office。
文摘The energetic particle detector on China's space station can determine the energy, flux, and direction of medium-and highenergy protons, electrons, heavy ions, and neutrons within the path of the station's orbit. It also assesses the linear energy transfer(LET)spectra and radiation dose rates generated by these particles. Neutron detection is a significant component of this work, utilizing a new type of Cs_(2)LiYCl_(6): Ce scintillator material along with plastic scintillators as sensors. In-orbit testing has demonstrated the efficient identification of space neutrons and gamma rays(n/γ). This data plays a crucial role in supporting manned space engineering, scientific research, and other related fields.
文摘基于Web of Science核心合集数据库,采用文献计量学方法对中国探月工程(2003-2024)的科研产出进行系统分析.通过量化评估1023篇SCI论文的时空分布特征、国际合作态势及学术影响力,揭示了中国探月工程对全球月球科学研究的贡献.研究表明,中国探月工程的实施使中国月球科学领域发文量占比提升至32.6%(2024年),工程产出论文的CNCI值(1.03)超越全球均值;科研突破集中于嫦娥四号(月球背面着陆巡视探测)与嫦娥五号(月球样品分析)任务,产出181篇高影响力论文;国际引用情况中,非中国机构占比显著增长,显示工程成果获得广泛国际认可.研究成果为评估中国深空探测计划的科学效益提供了定量依据.
文摘频率资源是支撑航天行业发展的核心战略资源之一,随着作为国际热点的月球开发利用逐渐朝着规模化方向发展,频率资源的需求愈发迫切.然而,在现有国际规则框架下,可提供给月球规模化开发利用的频率资源非常有限,供需矛盾日益加剧.本文围绕国际地月空间频率资源申请现状、工程任务规划与实施情况开展系统性数据分析,研究当前地月空间频率资源与SFCG(Space Frequency Coordination Group)月球区域频率划分建议的符合度,分析地月空间频率资源的利用态势,同时,利用自主开发的频率兼容性仿真平台,对国际上的典型任务进行了定量化干扰计算分析,提出了后续地月空间探测、开发利用等领域的用频建议,为相关工程任务的规范有序实施提供参考.
