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01 August 2025, Volume 45 Issue 4 Previous Issue   

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Cutting-edge scientific issues in ice giant exploration WANG Chi, LI Hui, KONG Dali, WANG Yuxian, YANG Zhongwei 2025, 45 (4):  1-11.  doi: 10.16708/j.cnki.1000-758X.2025.0053 Abstract ( 253 )   PDF (9196KB) ( 254 )   Save Exploring ice giants and their moons stands as one of the frontiers in deep space exploration and space science research. Current international planetary exploration plans all include missions to ice giants. Focusing on China’s future ice giant exploration missions, the current status of ice giant exploration is investigated, and seven key scientific questions are identified and summarized. By comparing and analyzing the characteristics of ice giant systems, and combining with the development trends in planetary exploration, the prospects and recommendations for future ice giant missions are proposed. Neptune-Triton exploration as a priority for ice giant missions is highlighted. Future exploration can be broadly divided into three subjects: exploring extraterrestrial oceans and life, understanding Kuiper belt objects and solar system evolution, and investigating ice giant systems to understand planetary origins and evolution. Analyzing the scientific objectives for ice giant exploration provides a scientific reference for China’s future deep space missions. Related Articles | Metrics

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Analysis and implementation recommendations for ice giant orbital exploration missions YANG Mengfei, GAO Feng, MENG Wenqin, LI Hui, WANG Yuxian, BAI Fanlu, WANG Tong 2025, 45 (4):  12-22.  doi: 10.16708/j.cnki.1000-758X.2025.0054 Abstract ( 172 )   PDF (3639KB) ( 200 )   Save As the planets situated closest to the edge of the solar system, the ice giants preserve a significant amount of primordial gases from the early stages of the solar system's formation, which contains valuable information about the conditions of the original protoplanetary nebula and the locations of planetary formation. Ice giants serve as a key reference for the study of both the solar system and exoplanets. This study systematically reviews and analyzes foreign exploration proposals for ice giant orbiting missions, identifies the main technical challenges associated with these missions; and based on the scientific questions about the ice giants and their satellite systems, offers development recommendations for China's implementation of ice giant orbiting exploration. The scientific value of ice giant exploration lies in its potential to reveal their internal structure and formation history, their unusual magnetic fields and complex, variable space environments, as well as the investigation of Triton's subsurface ocean and potential biosignatures. Key technical challenges are identified in the study, including long-distance energy supply, tracking and communication, autonomous intelligence, and high-precision orbital design. The theoretical support and decision-making guidance for China's future planning and implementation of ice giant orbiting exploration missions are provided by the findings of this research. Related Articles | Metrics

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A study on subsurface ocean property inversion of icy moons using multi-frequency magnetic induction response WANG Yujie, LI Xizhi, KONG Dali 2025, 45 (4):  23-36.  doi: 10.16708/j.cnki.1000-758X.2025.0055 Abstract ( 68 )   PDF (10834KB) ( 34 )   Save The icy moons in the Solar System are of great scientific interest due to their potential subsurface oceans. Single-frequency magnetic induction response is limited in its sensitivity to the depths of conductive layers and often suffers from parameter degeneracy during inversion, making it challenging to uniquely determine the conductivity and thickness of subsurface oceans. The feasibility of the multi-frequency magnetic induction response method in inferring the properties of subsurface oceans in icy moons is investigated, and Jupiter's moon, Europa, is selected as a case study. The induced magnetic field of Europa is first simulated utilizing a specific internal structure model and a time-varying field extracted from Jovian magnetospheric models. Based on multiple sets of simulated data, a multi-start trust-region-reflective optimization method is applied to invert the ocean conductivity and thickness. The effects of noise levels, parameter combinations, and detection conditions (e.g., detection timing and orbital configurations) on the inversion results are also analyzed and discussed. The results indicate that, under high signal-to-noise ratio (SNR), multi-frequency magnetic induction response can effectively reduce the degeneracy between ocean conductivity and thickness. It provides more accurate parameter estimates compared with single-frequency magnetic induction response in a certain parameter space, but further information is still required to determine the unique and reasonable solution. When SNR decreases due to poor detection conditions or large noise, the ability of certain frequencies to constrain parameters is weakened, leading to the reduction of multi-frequency magnetic induction response inversion accuracy. Related Articles | Metrics

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A multi-angle spectral curve inversion model based on BRDF LIU Zhen, SUN Xu, SHA Jianjun, SUN He, WANG Degang, GAO Lianru 2025, 45 (4):  37-47.  doi: 10.16708/j.cnki.1000-758X.2025.0056 Abstract ( 88 )   PDF (10118KB) ( 63 )   Save To address the issue of low matching detection accuracy caused by differing inclination angles between the a priori spectral library and the measured hyperspectral image acquisition, a tilted spectral curve inversion model is proposed based on a kernel-driven bidirectional reflectance distribution function (BRDF). The spectral curves are firstly split according to the wavebands, and then the relationship between the reflectance of each waveband and the detection inclination is fitted according to the BRDF equation, to establish the reflectance inversion model. For the hyperspectral images collected at a specific inclination angle, the inversion algorithm is used to perform the a priori spectra at the corresponding inclination angle and match the detection. In the experiment, the multi-angle spectral data of the desert camouflage net and its background dry grassland are collected using the independently designed and assembled field multi-angle spectral measurement system, their spectral characteristics are analyzed, and the performance of various inversion algorithms is compared. The experimental results show that the reflectance of different features varies with the detection inclination in a similar trend, respectively, and the differences between the fitted and measured spectral curves are small, with the coefficients of determination of the two exceeding 0.83, and the spectral pinch angles of the spectra are all less than 1°. Compared with the a priori spectra acquired at different inclination angles, the a priori spectra generated by the inversion model with the same angle as the image acquisition have improved AUC values in the matched detection. The research enriches the related studies of multi-angle remote sensing and effectively applies multi-angle remote sensing to the field of hyperspectral target detection. Through the established inversion model, the accuracy of hyperspectral image matching detection is improved, which is of theoretical and practical significance.  Related Articles | Metrics

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A spatial enhanced Transformer based unsupervised pansharpening method XIONG Zhangxi, LI Wei, YANG Fei, LIN Hongyang 2025, 45 (4):  48-60.  doi: 10.16708/j.cnki.1000-758X.2025.0057 Abstract ( 52 )   PDF (17526KB) ( 21 )   Save Addressing issues such as insufficient spatial texture and spectral distortion in the fusion of panchromatic and multispectral images, an unsupervised pansharpening method based on spatially enhanced Transformer (Pan-SET) is proposed. Firstly, a multi-scale feature extraction module is designed to obtain features of panchromatic and multi-spectral images at different scales, thereby enhancing the generalization ability of features and the robustness of the model. Secondly, a high-frequency information extraction module is designed to extract high-frequency information from the panchromatic image. The multiscale features of the panchromatic and multispectral images, after undergoing simple fusion, are jointly input into the designed spatial enhanced Transformer along with the high-frequency information of the panchromatic image. The designed spatial enhanced Transformer consists of a self-attention mechanism and a spatial detail enhancement attention mechanism. The self-attention mechanism can capture self-similarity and extract long-range features, while the spatial detail enhancement attention mechanism ensures that only textures, edges, and detailed parts are enhanced. Finally, after fusion and enhancement through multiple layers of spatial enhancement Transformer, the features are reconstructed into multi-spectral images with high spatial resolution. Comparative experiments are conducted on the GF-2 and WV-3 data in PanCollection dataset, and seven quality evaluation indices are used to objectively assess the quality of the fused images obtained by various methods. The proposed method exhibits the best performance in terms of the quality evaluation index QNR on both datasets, with values of 0.9692 and 0.9327, respectively. The visual effects and quality evaluation indices of the fused images indicate that the proposed method outperforms the comparison methods both subjectively in visual perception and objectively in evaluation, effectively reducing the spatial-spectral distortion of the fused images. Related Articles | Metrics

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Distributed autonomous scheduling based on event trigger for heterogeneous satellite swarm QIN Jiahao, LI Baowei, BAI Xue, RAN Dechao, XU Ming, ZHANG Rui, HU Zhiqiang 2025, 45 (4):  88-101.  doi: 10.16708/j.cnki.1000-758X.2025.0061 Abstract ( 51 )   PDF (6453KB) ( 17 )   Save The application of earth observation satellite (EOS) is shifting from static to dynamic mission scenario, leading to an increasing demand for real-time observing capabilities. Consequently, an autonomous scheduling method is urgently needed to enable real-time mission responses and overcome the window constraints imposed by satellite telemetry command control (TT&C) systems. An event-triggered distributed autonomous scheduling method is proposed, which enables the autonomous closed-loop of target discovery, evaluation, and imaging. Firstly, an event-triggered distributed multi-satellite task negotiation framework is established utilizing the double layer contract network protocol (DLCNP). Secondly, a dynamic scheduling algorithm considering task priority based on the minimum conflict set is proposed to achieve real-time task assertion and conflict resolving. This algorithm provides an online solution for multi-satellite task negotiation. Finally, an iterative density cluster method is introduced to conduct clustering of high-value point targets. This method ensures the clustered point targets can be covered by a single imaging satellite, which effectively reduced observations required. The superiority of the event-triggered distributed autonomous scheduling method is verified by comparing its task completion rate with global optimization algorithm and communication load with blackboard inter-satellite structure. The pattern of task merging ratio is revealed by varying the size of the spread area and the number of targets. The proposed method can enhance the autonomy and emergency response capability of EOS swarm effectively. Related Articles | Metrics

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A mission planning method of high-orbit remote sensing satellites for multi-target detection LING Long, ZHU Yanqi, LU Zhijun, WANG Jie, WU Tongzhou, FENG Qian 2025, 45 (4):  102-113.  doi: 10.16708/j.cnki.1000-758X.2025.0062 Abstract ( 81 )   PDF (6944KB) ( 85 )   Save High-orbit remote sensing satellites have become an indispensable tool in modern remote sensing technology because of their broad field of view coverage， efficient observation timeliness and strong continuous imaging capabilities， which can effectively obtain key feature information of key areas and targets. High-orbit remote sensing satellites often face the application requirements of simultaneous monitoring and tracking of multiple targets in area gaze missions. In order to solve the problem of low task execution efficiency under the demand of multi-objective observation， this paper proposes a high-orbit remote sensing satellite imaging mission planning method based on intelligent optimization algorithm， innovatively designs an "evaluation matrix" as the objective function of the differential evolution algorithm to realize the multi-objective observation area planning， and uses the genetic algorithm to complete the observation path planning on this basis. The simulation results show that compared with the traditional method， the observation efficiency of the proposed method is increased by 28.84% on average， and the energy usage rate is reduced by 24.37% on average. This method can cover all the targets to be tracked with a small number of observations， effectively reduce the number and angles of satellites pointing maneuvers， and the algorithm has good parallelism and portability， which can be adapted to various application scenarios such as on-board autonomous mission planning and constellation cooperative observation. Related Articles | Metrics

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Multi-objective optimization of microwave power transmission system architecture with engineering consideration DONG Shiwei SHINOHARA Naoki 2025, 45 (4):  114-122.  doi: 10.16708/j.cnki.1000-758X.2025.0063 Abstract ( 111 )   PDF (5652KB) ( 105 )   Save In the last decade, space solar power satellites (SSPSs) have been conceived to support net-zero carbon emissions and have attracted considerable attention. Electric energy is transmitted to the ground via a microwave power beam, a technology known as microwave power transmission (MPT). Due to the vast transmission distance of tens of thousands of kilometers, the power transmitting antenna array must span up to 1 kilometer in diameter. At the same time, the size of the rectifying array on the ground should extend over a few kilometers. This makes the MPT system of SSPSs significantly larger than the existing aerospace engineering system. To design and operate a rational MPT system, comprehensive optimization is required. Taking the space MPT system engineering into consideration, a novel multi-objective optimization function is proposed and further analyzed. The multi-objective optimization problem is modeled mathematically. Beam collection efficiency (BCE) is the primary factor, followed by the thermal management capability. Some tapers, designed to solve the conflict between BCE and the thermal problem, are reviewed. In addition to these two factors, rectenna design complexity is included as a functional factor in the optimization objective. Weight coefficients are assigned to these factors to prioritize them. Radiating planar arrays with different aperture illumination fields are studied, and their performances are compared using the multi-objective optimization function. Transmitting array size, rectifying array size, transmission distance, and transmitted power remaine constant in various cases, ensuring fair comparisons. The analysis results show that the proposed optimization function is effective in optimizing and selecting the MPT system architecture. It is also noted that the multi-objective optimization function can be expanded to include other factors in the future. Related Articles | Metrics

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The load design and implementation of LT-4 space-borne SAR LI Guangting, TAN Xiaomin, LI Caipin, NIE Shikang, LIN Chenchen, ZHU Yalin, LIU Bo 2025, 45 (4):  123-130.  doi: 10.16708/j.cnki.1000-758X.2025.0064 Abstract ( 174 )   PDF (5812KB) ( 343 )   Save In order to meet the requirement of high revisit and wide coverage of SAR system for national disaster prevention and reduction, the world’s first geosynchronous orbit SAR named Land Exploration 4rd(LT-4) was designed and developed. The satellite uses a ring-shaped reflector antenna and combined with phased array feed system, operating at L-band. The particularity of the orbit makes the satellite naturally have the characteristics of high revisit and wide coverage. In order to give a comprehensive description of the SAR payload system of LT-4, the characteristics of high orbit SAR which are different from low orbit SAR are described, and the key performance parameters of SAR payload are given. Then the working process of SAR payload is introduced, and the main functions and performance of the key equipment of SAR payload are expounded. At last, the history of load development for more than ten years is briefly described, and the load integration test items and test verification are given. The world's first high-orbit SAR image is obtained when the SAR payload works for the first time on orbit. The image information is rich and the payload’s on-orbit state is stable. The imaging results show that the SAR payload design is reasonable and the ground test and verification are sufficient, which can provide favorable information support for national disaster prevention and reduction. Related Articles | Metrics

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Rapid design of low-thrust multiple gravity-assist trajectory based on Fourier series FU Liangyong, CHEN Shoulei, LU Dongning, LIU Yiwu 2025, 45 (4):  131-143.  doi: 10.16708/j.cnki.1000-758X.2025.0065 Abstract ( 76 )   PDF (4940KB) ( 65 )   Save To address the inefficiency of traditional indirect and direct methods in designing low-thrust fuel optimal rendezvous trajectories under gravity-assist maneuvers, a rapid trajectory optimization algorithm based on finite Fourier series shaping is proposed. This method transformes the trajectory optimization design into a low-computation nonlinear programming problem that adheres to thrust and gravity-assist constraints under analytically satisfying boundary conditions, thereby significantly enhancing solution efficiency. Additionally, a feasible range estimation strategy for the number of trajectory revolutions is proposed to overcome the limitation that the optimality of shape-based method influenced by the flight revolution; however, the current determination of flight revolution still relies on empirical trial and error. Moreover, to address the challenge of accurately approximating complex low-thrust trajectories under multiple gravity-assist using shape-based method, the overall iterative optimization and segmented optimization strategy are proposed. The feasibility and efficiency of the proposed method and its corresponding strategies are demonstrated by comparing simulation results with and without gravity-assist design, as well as single and multiple gravity-assist designs. The results show that, without relying on any prior information, the proposed method can design reasonable three-dimensional low-thrust rendezvous trajectories within seconds, and reasonable three-dimensional low-thrust single or multiple gravity-assist rendezvous trajectories within tens of seconds. Related Articles | Metrics

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Rigid-flexible coupling design and driving force analysis of modular deployable antenna structure TIAN Dake, ZHANG Hao, WANG Yongbin, FANG Jishou, JIN Lu, SHI Zuwei, FAN Xiaodong 2025, 45 (4):  144-153.  doi: 10.16708/j.cnki.1000-758X.2025.0066 Abstract ( 287 )   PDF (10574KB) ( 402 )   Save Modular deployable antenna has the characteristics of good versatility, strong adaptability and expansion flexibility, and is a configuration form with great development potential to meet the needs of in-orbit assembly and construction of large-scale antenna in the future. In order to better grasp the mechanical characteristics of the antenna structure, the rigid-flexible coupling design and driving force analysis of the antenna structure are developed. Firstly, a scheme design of modular deployable antenna structure is carried out, and the structure composition and deployment/stowed principles are described. Secondly, based on the analytical geometric method, a mathematical model of the equivalent envelope circles is developed, and key parameters such as the angle of the rib unit are obtained, then the three-dimensional model of deployable antenna structure is established. Thirdly, the flexible processing of radial long beams such as upper beam, diagonal beam and lower beam is carried out, and a multi-body dynamic model of rigid-flexible coupling of modular deployable antenna mechanism is established by multi-body dynamics simulation software. Finally, the change laws of the deployable driving force of single module and multi module antennas at different confinement positions are analyzed from the aspects of gravity and no gravity. The results show that if there is gravity in the deploying process, the choice of constraint position has a great influence on the driving force. In the absence of gravity, the antenna constraint position has little effect on deployment. The structural design and multi scheme driving force analysis can provide some reference for the prototype development and engineering application of this antenna. Related Articles | Metrics

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Evaluation method of LEO navigation augmentation self-interference cancellation performance SU Qianqi, ZHANG Lixin, CHEN Liucheng, BIAN Lang, LIU Lijuan, AN Yuanyuan, YAN Tao, WANG Ying, MENG Yansong 2025, 45 (4):  154-164.  doi: 10.16708/j.cnki.1000-758X.2025.0067 Abstract ( 34 )   PDF (5816KB) ( 9 )   Save With the rapid development of LEO satellite constellations, LEO navigation augmentation has become a research hotspot in the field of satellite navigation. LEO navigation augmentation adopts the "satellite-based monitoring + signal augmentation" system, LEO navigation satellites need to broadcast LEO navigation augmentation signals to the ground while receiving GNSS signals. LEO navigation augmentation signals are usually broadcast in the GNSS frequency band, so the LEO navigation augmentation signal broadcast to the ground is a strong self-interference signal with respect to the received signal, and how to eliminate the effect of the self-interference signal on the received signal is the key to realizing the simultaneous transceiver in the same frequency band. The self-interference cancellation scenario and method of LEO navigation augmentation are studied, and the performance evaluation method applicable to LEO navigation augmentation self-interference cancellation is proposed for the characteristics of LEO navigation augmentation signals, which uses the correlation power difference of the interfering signals before and after self-interference cancellation to characterize the self-interference cancellation capability. The signal power value after interference cancellation is obtained through the correlation power difference, and the equivalent carrier-to-noise ratio loss and the code tracking error evaluation method under the influence of residual self-interference are derived to evaluate the influence of residual self-interference signal on the expected signal reception. A typical navigation signal BPSK(2) and BOC(1,1) are used for simulation verification, and the results show that when the interference-to-noise ratio is 30dB, the self-interference cancellation ability of the existing method is 30.98dB and 33.04dB, and the self-interference cancellation ability of the proposed method is 58.80dB and 58.96dB. Through comparative verification, it can be concluded that the proposed self-interference cancellation performance evaluation method outperforms existing methods. It provides a more accurate assessment of the self-interference cancellation capability in LEO navigation augmentation, serving as a performance evaluation reference for self-interference cancellation methods in this context. Related Articles | Metrics

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High-accuracy estimation algorithm for fast changing Doppler JIN Lei, ZENG Fuhua, JIANG Youbang, GUO Xiao 2025, 45 (4):  165-175.  doi: 10.16708/j.cnki.1000-758X.2025.0068 Abstract ( 42 )   PDF (4925KB) ( 19 )   Save A high-accuracy estimation algorithm for fast changing Doppler frequency shift based on forecast information rough compensation and multi-stage accurate correction is proposed in deep space TT&C(Tracking Telemetry and Command) communication systems, Which overcomes the difficulty that the traditional algorithm has poor frequency estimation accuracy and low receiver sensitivity for deep space ultra-long distance TT&C signal with large-range frequency dynamic and extremely low Signal Noise Ratio(SNR). The carrier frequency of deep space TT&C signal is roughly compensated based on spacecraft orbit forecast information to compress the search scope of Doppler frequency shift. In order to cancel the frequency dynamic change, the process structure of multi-stage frequency correction is employed to accurately correct the Doppler frequency shift, first-order frequency rate and second-order frequency rate of deep space TT&C signal. The combined method with peak calculation and time-frequency correction is applied to accurately estimate fast changing Doppler frequency shift. The experiments and analysis verify that the proposed algorithm can achieve the frequency estimation precision up to 0.1Hz and the receiver sensitivity low to -160.4dBm for deep space ultra-long distance TT&C signal with large-range frequency dynamic and extremely low SNR, and significantly improve the frequency estimation precision and the receiver sensitivity in deep space TT&C communication systems.  Related Articles | Metrics

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Spacecraft movement monitoring method and verification based on radio measurement CHEN Lue, LU Weitao, WANG Xiaoyang, ZHANG Yujia, MAN Haijun, HAN Songtao 2025, 45 (4):  176-182.  doi: 10.16708/j.cnki.1000-758X.2025.0051 Abstract ( 102 )   PDF (4024KB) ( 35 )   Save In terms of the characteristics of radio signals typically emitted by spacecraft in high Earth orbit space and cislunar space during orbital maneuvers, passively receiving and processing techniques for radio signals are employed to achieve sensitive andrapid motion monitoring of spacecraft in orbit. The common technical methods used for spacecraft in orbit motion monitoring are analyzed，and a passive monitoring strategy based on radiometric measurements is proposed. Firstly, based on the operational characteristics of the transmitted telemetry, data transmission, and carrier signals from the target spacecraft, the target spacecraft signal is tracked and received by radio receiving antennas. Secondly, the target spacecraft downlink radio signal is sampled and recorded by the sampling and recording equipment. Subsequently, this paper focuses on the processing and analysis of the target's downlink signals by software-defined radio mode, accurately extracting sensitive features related to the target's motion such as signal frequency, amplitude, and phase changes. The orbit control quantity estimation algorithm based on open-loop Doppler frequency is proposed to evaluate the target's motion state. Finally, the effectiveness of the motion monitoring is assessed. The results indicate that accurate and sensitive monitoring of the orbital maneuvers and attitude adjustment processes of Earth high orbit spacecraft has been achieved based on actual experiment. The starting and ending time of the orbit control is accurately monitored, and the orbit control quantity in the line of sight direction of the station is estimated to be 4.1m/s, suggesting that this Earth high orbit spacecraft adopted a small thrust continuous orbit change mode for orbital maneuvers. The signal monitoring of the lunar spacecraft orbit maneuver process is realized, and its frequency, amplitude and phase characteristics are extracted respectively, and the orbit control quantity in the line of sight direction of the station is estimated to be 0.91m/s. The spacecraft motion monitoring method based on radiometric measurements effectively compensates for the limitations of traditional radar and optical measurements in monitoring spacecraft motion and complements them. This method is suitable for a variety of new application scenarios, and provides a feasible technical solution for the future monitoring of earth high orbit and cislunar space spacecraft. Related Articles | Metrics

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Optimization of solution strategy for short baseline precise GUO Huizhi, HAN Baomin, SUN Lingyang, XIAO Wei 2025, 45 (4):  183-193.  doi: 10.16708/j.cnki.1000-758X.2025.0099 Abstract ( 41 )   PDF (11964KB) ( 27 )   Save Short baseline precise common-view time transfer is one of the fundamental tasks in the time-frequency domain and has become a research hotspot of GNSS time-frequency. In order to improve the accuracy and reliability of short baseline precise common-view time transfer, various strategies are compared, and an optimization scheme is presented in this paper based on the results of fiber optic bidirectional time transfer experiments. Experiments are conducted, using continuous observation data from multiple tracking stations in Xi'an for multiple days. The experimental results show that it is not advisable to use any ionospheric and tropospheric correction models for ultra short baseline situations. When the baseline is long, appropriate tropospheric and ionospheric correction models must be used. The ionospheric delay modified by the ionosphere-free combination can significantly improve the accuracy of the results by up to 76.9%. The result of the accuracy improvement effect is not obvious by correcting the troposphere. The number of visible satellites can be increased by appropriately reducing the elevation mask, and the results can be improved with this method. Bidirectional filtering can improve convergence, and the time transmission precision can be improved by 40.9%.  Related Articles | Metrics

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Dynamics of droplet transport by electrowetting in different gravity levels HUO Xiaozhi, WANG Qing, GU Junping, WANG Zhantao, WANG Qinggong, YU Qiang 2025, 45 (4):  61-69.  doi: 10.16708/j.cnki.1000-758X.2025.0058 Abstract ( 40 )   PDF (7210KB) ( 19 )   Save Electrowetting is an effective method for interface manipulation and fluid transport, and it has great application prospects both on Earth and in space due to the advantages of fast response, low power consumption and controllable path. Previously, the influence of gravity is ingnored in the study of the dynamics of droplet transport by electrowetting. However, the gravity must be taken into account when droplets are transported along the direction of gravity or against gravity. Therefore, the dynamics of droplet transport by electrowetting in different gravity levels is studied for space application. In this work, a droplet transport system by electorwentting is designed, and a simulated method of droplet transport by electrowetting is established. In addition, a method of continuous droplet transport is proposed by capturing droplet’s front edge to set activation states of electrodes. Then, the dynamics of long-distance droplet transport by electrowetting is studied in a zero-gravity environment, and the influence of gravity level on droplet transport by electrowetting is analyzed. The continuous and rapiad transport of droplet is achieved using this eletrocwetting system. The simulated results show that the transport velocity of droplet reaches about 0.28m/s. The droplet transport velocity increases almost linearly with the applied voltage. The droplet velocity decreases with the droplet size because the large base diameter of the droplet increases the friction between the droplet and the plate. The gravity’s direction and level affect the droplet’s motion significantly. The droplet deforms under the gravity effect. However, the electrowetting force is still able to overcome the gravity level of -2g, and the electrowetting system shows a good anti-gravity ablity. The constraint laws of droplet transport by electrowetting in different gravity levels are obtained, which provide theoretical basis for droplet collection and tansport in space environment. Related Articles | Metrics

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Performance analysis of on-orbit testing of mechanically pumped two-phase loop for spacecraft MENG Qingliang, WEI Guanglang, YU Feng, YANG Tao, ZHAO Zhenming, ZHU Xu 2025, 45 (4):  70-78.  doi: 10.16708/j.cnki.1000-758X.2025.0059 Abstract ( 40 )   PDF (7542KB) ( 26 )   Save Mechanistically pumped two-phase loop (MPTL) is a two-phase heat transfer device, which possesses the strong heat transfer ability through the release of latent heat of liquid and vapor phase change during flow boiling process. MPTL shows a promising prospect in thermal control of spacecraft.The objective of the present study is to focus on the working characteristics and stability of MPTL under the microgravtiy environment on orbit. One MPTL, which included one shield centrifugal pump, one two-phase temperature controlling accumulator and one micro channel evaporator, was designed and constructed to investigate the characteristics of start-up, phase-changing heat transfer, and temperature-controlling for MPTL aboard one satellite. Test results shows that MPTL shows good working performance and stable operating behavior in microgravity environment. The two-phase accumulator presents good heat transfer performance under microgravity condition. Its temperature control accuracy reaches to ±0.1K. The passive cooling function of accumulator is validated, and its cooling rate reaches to 1℃/min. The temperature difference between the measuring points of vapor and liquid phase for the accumulator are in the range of 0.3～1.0K when the pump is working. The temperature control accuracy of the evaporator is in the range of ±0.1～±0.3K at the two rotation speeds. Superheating phenomenon takes place during the phase changing process of the loop and it leads to a higher 7～8K temperature at the evaporator’s outlet than the temperature control point. By comparing the results under the two rotation speeds, the superheat time and superheat temperature are related with the rotation speeds. The two-phase temperature controlling accumulator using the capillary structures can assure the function of high-precision temperature control and high-efficiency two-phase fluid management and control for MPTL under the microgravity condition. The phase transition characteristic for vapor-liquid is related to the mass flowrate of the loop. The stability of temperature on the evaporator is related to the fluid quality of its interior fluid. The study would contribute to the engineering design basis for the technology of two-phase flow and heat transfer, and would promote the development of active two-phase thermal control technology for space. Related Articles | Metrics

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Ground verification of novent fluid filling and recovery technology WANG Zhenrui, HUANG Liping, HE Zhenhui 2025, 45 (4):  79-87.  doi: 10.16708/j.cnki.1000-758X.2025.0060 Abstract ( 45 )   PDF (3710KB) ( 16 )   Save No-vent filling technology utilizes the characteristic relationship between the saturation pressure and the temperature of a vapor-liquid two-phase working fluid in an evaporation and condensation system, achieving a fluid filling/refilling technology with neither moving components nor vent requirement for pressure reduction. In order to equivalently verify the feasibility and designed efficiency of the recycling and refilling method in microgravity on the ground, the level of fluid bottle for refilling or recovery is adjustable, with respect to the system to be refilled or recovered, to offset the influence of gravity as much as possible. Recovery and refilling tests for working fluids of R134a, fully degassed FC-72, and insufficiently degassed FC-72 are conducted on ground. The data of pressure and temperature of the loop system are used to analyze the internal transport during the working fluid replacement process. The pressure change rate (less than 0.1kPa/s) is verified to be a qualified criterion to end the filling or recovery. The results show that both fluids working under medium pressure and low pressure can achieve recovery rates and filling rates of over 95%, meeting the design requirements. Considering that the phenomenon of vapor-lock in ground pipelines disappears under microgravity, resulting in a smaller temperature difference required to drive the working fluid, and making it easier to replace the working fluid, it can be considered feasible to use no-vent filling technology for on-orbit working fluid replacement，and that the level of working fluid bottle is not continuously adjustable leads to inefficient offset of the gravity influence, which in turn constitutes the main measurement error of the filling rates or recovery rates. Depending on the application requirements, this method can also be improved and applied to the replacement or refilling of working fluids with larger capacities. Related Articles | Metrics