空间科学学报

Shape and Sooting Properties of Methane Laminar-jet Diffusion Flames in Microgravity

, Available online , doi: 10.11728/cjss2025-0166

Abstract(217) PDF 2808KB(4)

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Shape and sooting properties are fundamental characteristics of hydrocarbon fuel diffusion flames. The study of laminar diffusion flame behavior under microgravity conditions provides a crucial approach for elucidating the physical and chemical mechanisms of diffusion combustion and for establishing turbulent diffusion combustion models. On-orbit microgravity experiments were conducted on coaxial coflow methane laminar jet diffusion flames using the combustion science experiment cabinet aboard the Chinese Space Station, with a focus on analyzing the influence of coflow conditions on flame morphological features and soot characteristics under microgravity. The main experimental conditions included: coflow gases with a high-oxygen concentration, air, N₂-diluted air, and Ar-diluted air; a coflow velocity to jet velocity ratio of less than 0.5; methane flow rates producing both far-field and near-field jet flames; and ambient temperature and pressure conditions. The results indicate that a simplified model based on jet flow field similarity theory can effectively predict the shape of microgravity flames in the far-field region of the jet. The coflow composition affects the flame shape by altering the combustion stoichiometry. The near-field flame length is independent of the coflow velocity but inversely proportional to the stoichiometric mixture fraction Z_st, while the maximum flame diameter is proportional to the square root of the inverse of Z_st. When air is diluted with inert gases in the coflow, the soot formation-dominated zone in the jet diffusion flame decreases, whereas the soot oxidation-dominated zone expands. The soot content in the flame decreases with increasing volume fraction of inert gas, with the dilution effect and thermal effect on soot formation characterized by the inert gas volume fraction and flame temperature, respectively.

, Available online , doi: 10.11728/cjss2025-0145

Abstract(85) PDF 1226KB(0)

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A Dataset of Kp index in the Chines Region (2022-2024)

, Available online , doi: 10.11728/cjss2025-0131

Abstract(321) PDF 2671KB(1)

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In 2011, the National Space Science Center of the Chinese Academy of Sciences established the Chinese Academy of Sciences Space Environment Monitoring Network. Currently, its geomagnetic observatory stations include those in Mohe, Beijing, Langfang, Sanya, and Fuke. By integrating and processing the H-component monitoring data from fluxgate magnetometers at these five geomagnetic observatory stations, we have developed a geomagnetic Kp index that can effectively identify the day-to-day variation characteristics of the geomagnetic regular daily variation, reflect the seasonal and local time effects of geomagnetic disturbances, and is suitable for the distribution characteristics of China's geomagnetic observatory network. This dataset contains the geomagnetic Kp indices for the five geomagnetic observatory stations from 2022 to 2024. It addresses the current situation where the official Kp index is released with a two-week delay, failing to meet operational requirements, and can better describe geomagnetic disturbances in the Chinese region. It is expected to provide data support for space weather research in the Chinese region.

Research on the Performance of BeiDou-3 Broadcast Ephemeris and Ionospheric Model from 2020 to 2025

, Available online , doi: 10.11728/cjss2025-0101

Abstract(229) PDF 1608KB(4)

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The BeiDou Navigation Satellite System (BDS-3) officially began providing global services on July 31, 2020. As the core component of satellite navigation systems, the space segment's service capability determines the overall system performance. This paper first introduces calculation and analysis methods for broadcast orbit errors, broadcast clock errors, Signal-in-space range error and broadcast ionospheric errors. Then, based on the final products of German Geosciences Research Centre (GFZ)and International Global Navigation Satellite System Monitoring and Assessment System (iGMAS),it conducts an evaluation of the changes in broadcast ephemeris accuracy and ionospheric model precision throughout a complete cycle from 2020 to 2025. Research shows that the BDS‑3 broadcast orbit error shows a clear dependence on satellite type, with MEO satellites outperforming IGSO satellites. Compared with GFZ products ,the 95% RMS of the radial ,along‑track and cross‑track error falls from 0.104 m、0.482m、0.589m respectively in 2020 to 0.080 m、0.351m、0.364 m respectively in 2025; and compared with iGMAS products , these data fall from 0.086m、0.386m、0.461m respectively in 2020 to 0.073m、0.341m、0.350m in 2025.Regarding broadcast clock error, based on GFZ products,the 95% RMS improves from 0.705m in 2020 to 0.540 m in 2025; and based on iGMAS products, the 95% RMS in 2020 is 0.811m and 0.640m in 2025.The SISRE of MEO satellites is generally smaller than that of IGSO satellites, and the statistical accuracies of 95% RMS of SISRE in 2020 based on GFZ and iGMAS products reaches 0.705m and 0.817m,and in 2025 reaches 0.549m and 0.645m, respectively. In terms of ionospheric model error, during the solar minimum(2020) the BDGIM model’s VTEC average RMS is 3.193 TECU for the Center for Orbit Determination in Europe(CODE), and 3.176TECU for iGMAS(vs. 7.359 TECU for the Klobuchar model, iGMAS for 7.367TECU), while during the solar maximum(2025) they rise to 11.481 TECU and 22.211 TECU for CODE, 10.493TECU and 21.802TECU for iGMAS respectively, demonstrating BDGIM model’s stronger resistance to disturbances. And the assessment results can provide support for BDS performance optimization.

Cosmic Ray Muon Count Dataset from Siziwang Station in Inner Mongolia (2023–2025)

, Available online , doi: 10.11728/cjss2025-0133

Abstract(264) PDF 1855KB(0)

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The Muon Telescope at Siziwang Station in Inner Mongolia is used to detect the secondary cosmic ray muons reaching the ground. Muon signals generated by the telescope’s 48 detection units undergo processing steps including amplification, discrimination, shaping, and directional coincidence calculation to produce raw muon counts. These counts are further refined through atmospheric pressure correction calculations to form a dataset of corrected muon counts in 15 directions, with a temporal resolution of 1 hour. The muon data can sensitively reflect diurnal variations, long-term variations of cosmic rays, and short-term Forbush decrease perturbations induced by coronal mass ejections. Spanning from May 2023 to April 2025, this dataset covers the high-activity phase of the 25th solar activity cycle. It provides valuable data resources for research on solar eruptions, their interplanetary disturbance propagation, and geomagnetic response processes, while also supporting space weather early warning efforts.

Standard Dataset of Ionospheric Plasma Bubbles over Southern China Based on Airglow Observation

, Available online , doi: 10.11728/cjss2025-0097

Abstract(446) PDF 1207KB(5)

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Airglow imaging observations, with their high spatiotemporal resolution and large-scale continuous monitoring capability, provide a crucial means for studying the fine horizontal structures and evolutionary characteristics of ionospheric equatorial plasma bubbles. However, the current lack of high-quality, professionally annotated plasma bubble datasets severely restricts the application of supervised artificial intelligence (AI) algorithms in this field. To address this issue, this study constructs the first standardized dataset of ionospheric plasma bubbles based on airglow observations, including plasma bubble event data products and precise contour annotation data products. The dataset is derived from continuous observations over a full solar activity cycle (2012–2022) by a 630 nm band airglow imager at the Qujing Station in Yunnan, China. All raw data underwent standardized preprocessing, including image enhancement, azimuth correction, geometric distortion correction, and geographic coordinate projection. Expert teams then performed plasma bubble event identification and contour annotation. With a high temporal resolution of 3 minutes, the dataset systematically documents plasma bubble events under varying solar activity intensities, covering multiple typical morphologies such as "I-shaped" and "Y-shaped" structures. This dataset provides high-quality benchmark data for developing high-precision supervised AI algorithms, facilitating automated detection and morphological evolution research of ionospheric plasma bubbles based on airglow imaging.

Standard Dataset of Solar Lyman-alpha Flare Events in 2024

, Available online , doi: 10.11728/cjss2025-0079

Abstract(871) PDF 475KB(1)

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Solar flares are the most intense eruptive phenomena in the solar atmosphere, releasing large amounts of energy and producing electromagnetic radiation across various wavelengths. Research on solar flares is crucial for understanding solar activity, space weather forecasting, and protecting the Earth's space environment. Based on full-disk solar images collected by the "Kuafu-1" satellite, this dataset systematically records solar flare events observed in the Lyman-alpha band throughout 2024 using an independently developed automatic solar flare identification and key parameter extraction algorithm. This algorithm effectively avoids interference from cosmic rays and particle storms, identifies flares of different intensity levels, and can separately identify and track multiple flares occurring simultaneously on the solar disk. The dataset includes key parameters such as flare start and end times, duration, location, and significance, and contains data products including flare identification process documentation, flare event lists, quick-view images of flares at peak moments, and movies of flare regions. This dataset provides important scientific data support for solar physics research, space weather forecasting, and related fields.

Accurate Fruit and Vegetable Detection Method for Space Station Cargo Bay

, Available online , doi: 10.11728/cjss2025-0080

Abstract(79) PDF 1490KB(1)

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The practical application of machine vision technology in the management of space station cargo bay is in the preliminary stage, in order to solve the lack of detection accuracy due to the narrow space, occlusion and light problems in the space station cargo bay, an improved algorithm for the detection of fruits and vegetables in the space station cargo bay based on YOLO11 is proposed: LEBR-YOLO. the method improves convolution to an efficient input feature extraction stem layer combining spatial information and edge information. A two-layer attention mechanism is added to improve the feature extraction capability. An improved lightweight shared deformable detection module is introduced to improve the detection ability under occlusion. Migration learning is also used as a method to optimize the model to compensate for the lack of dataset and improve the generalization ability. Experiments show that the method achieves 95.3% accuracy, 88.6% recall and 93.9% mAP@0.5 on the homemade fruit and vegetable dataset, while still maintaining a low model complexity to meet the needs of the Lightship cargo spacecraft in orbit. The method can be effectively used for the detection of fruit and vegetable items in the space station, which improves the detection accuracy and effectively reduces misdetection and omission.

Comparative analysis of synchronous observations of large-scale moving atmospheric disturbances and large-scale moving ionospheric disturbances

, Available online , doi: 10.11728/cjss2025-0069

Abstract(78) PDF 1193KB(3)

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The observation advantage of using CHAMP satellite to simultaneously observe atmospheric mass density and electron density over a large span is reported in this paper. On March 19, 2002, a long-distance propagation event of Large Scale Traveling Atmospheric Disturbances (LSTAD) and Large Scale Ionizing Traveling Disturbances (LSTID) was reported. With a sudden increase in AE index at around 0400 UT, the CHAMP satellite immediately observed LSTAD and LSTID propagating together in the northern hemisphere. In the following approximately 6 hours, these neutral/ionization density disturbances continued to propagate southward, crossing the equator and entering the southern hemisphere, ultimately disappearing near the polar regions of the southern hemisphere. On the other hand, the observation results of ground-based GNSS station chains confirm the existence of LSTID observed by satellites. Comparative analysis shows that LSTADs and LSTIDs excited by the same driving source exhibit significant differences in phase velocities propagating along the meridional direction, resulting in their disturbance phases on the same orbit often not corresponding one-to-one.

Propagation of waves in the middle and upper atmosphere excited by intense events at the earth’s surface and lower atmosphere

, Available online , doi: 10.11728/cjss2025-0154

Abstract(93) PDF 1621KB(9)

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Severe events in the Earth's surface and lower atmosphere—such as volcanic eruptions, earthquakes, typhoons, thunderstorms, and anthropogenic explosions—can excite various types of waves. These waves propagate into the middle/upper atmosphere and ionosphere in the form of acoustic and gravity waves, exerting significant impacts on these regions. Such events provide typical case studies for investigating the physical mechanisms of coupling between Earth's various spheres. This paper reviews the observational and research findings of Professor Xiao Zuo's team regarding the effects of severe events like earthquakes and typhoons on the ionosphere. The paper also highlights the establishment of a dual-layer airglow observation network over China and the utilization of this detection system to study the propagation characteristics and effects of gravity waves excited by events such as volcanic eruptions, typhoons, and thunderstorms in the middle/upper atmosphere and ionosphere. The research results reveal that although gravity waves generated by volcanic eruptions cannot propagate directly over long distances in the middle and upper atmosphere, they can achieve extensive and long-range transmission through ocean-atmosphere interactions. The background atmospheric structure plays a crucial role in gravity wave propagation, with atmospheric waveguides enabling anomalous long-distance propagation of gravity waves. Although small- to medium-scale gravity waves have difficulty directly propagating upward to the thermosphere, secondary wave mechanisms can effectively facilitate their propagation from the middle atmosphere to the upper atmosphere. Furthermore, studies on typhoon events provide direct observational evidence of how severe lower atmospheric events influence the upper atmosphere and ionosphere.

A Muti-Collision Avoidance Maneuver Optimization Method Based on Sequential Convex Optimization

, Available online , doi: 10.11728/cjss2025-0048

Abstract(113) PDF 1065KB(11)

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As the number of spacecraft and space debris in near-Earth orbit (NEO) increases, and the number of encounters between spacecraft and space debris continues to rise, it is imperative that spacecraft possess the capability to avoid multiple space debris objects. A multi-collision avoidance method based on sequential convex optimization, which is designed to achieve short-term rendezvous of multiple space debris objects while considering the constraints of spacecraft thrust and collision probability, has been proposed. First the continuous thrust control problem is transformed into a planning problem for impulse thrust. Then the relative dynamics and constraints are convexified to solve the planning problem using the sequential convex optimization method. The proposed method has been demonstrated to be effective in reducing the risk of spacecraft collision with space debris in the avoidance problem for multiple targets. It can also carry out long-time avoidance maneuver planning for low-thrust spacecraft and ensure lower fuel consumption. Furthermore, the solution to the sequence convex optimization problem has been shown to have a fast solution speed, making it suitable for autonomous computation.

Calibration Method and Implementation for the Lunar Penetrating Radar on Chang'e-7 Mission

, Available online , doi: 10.11728/cjss2025-0102

Abstract(156) PDF 2189KB(17)

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The Chang'e-7 mission carries a Lunar Penetrating Radar (LPR) for investigating shallow subsurface structures. To ensure data validity and enhance measurement accuracy, we developed a space-qualified calibration protocol for the penetrating radar system. Successful calibration tests confirmed all performance metrics meet scientific requirements. The acquired transfer function and time-varying gain (TVG) curves establish a robust calibration baseline for lunar data processing. This methodology provides a technical framework for future deep-space radar missions.

Dataset of Solar Active Regions in the Solar Full-disk Magnetograms

, Available online , doi: 10.11728/cjss2025-0086

Abstract(116) PDF 686KB(7)

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Solar active regions are key source regions of intense solar phenomena such as solar flares and coronal mass ejections (CMEs). Accurate identification of these regions can help forecast the impact of solar activities on Earth's environment. This dataset utilizes solar full-disk magnetograms observed by the Helioseismic and Magnetic Imager onboard the Solar Dynamic Observatory (2010-2019), combined with NOAA AR numbers provided by the SolarMonitor website. The active regions are annotated using an image processing-based recognition method along with manual labeling. The dataset consists of 6,975 solar full-disk magnetograms, taken every 12 hours, with a total numbe of 19,098 annotations consisting of the active-region informationfor each magnetogram.This dataset serves as a benchmark resource for developing deep learning solar active region detection models, and aims to enhance predictive capabilities for severe space weather phenomena through physics-informed training samples.

Design and Simulation Analysis of a Spaceborne Fabry–Perot Interferometer (FPI) for the Near-Space Atmospheric Wind Field

, Available online , doi: 10.11728/cjss2025-0041

Abstract(144) PDF 1189KB(12)

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Currently, there are relatively few spaceborne methods for detecting near-space atmospheric wind fields, and the Fabry–Perot Interferometer (FPI) is one of the more important and widely used detection techniques. This paper mainly introduces a satellite-based FPI wind measurement instrument developed by the National Space Science Center, including optical design, structural design, thermal control design, optical simulation, and result analysis. First, the optical design is discussed based on the wideband detection requirements, and the imaging system’s image quality is evaluated. Then, the key points of the instrument's structural design and the thermal control solution for the imaging part are presented, along with a translational filter switching device driven by a trapezoidal lead screw and a micro reduction stepper motor or micro linear motor. The paper also explores the relationship between the temperature control accuracy of the instrument’s core components (the etalon) and wind measurement errors. A combined active and passive design is adopted to minimize the impact of temperature fluctuations on the results, which is verified through simulations. Finally, based on optical simulation data, wind speed inversion and accuracy analysis of the satellite-based FPI instrument are conducted. The wind speed errors at the 557.7 nm and 762.0 nm bands are -1.722 m/s and -2.3672 m/s, respectively, indicating that the spaceborne instrument design meets the wind measurement requirements.

Teleimpedance Control for Lunar Construction Based on Biomechanical Impedance Identification of Human Body

, Available online , doi: 10.11728/cjss2025-0142

Abstract(148) PDF 1684KB(6)

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In recent years, with the continuous progress of lunar exploration, remote robotic arms face the need for highly safe, accurate, and transparent control strategies in uncertain and unstructured environments when performing tasks such as lunar base construction and facility setup. Humanoid variable impedance control methods can ensure both safe interaction between the robotic arm and the environment and high-precision control, providing a solution to the challenges of human-robot collaboration in lunar construction. This study investigates a teleoperated variable impedance robotic arm control strategy based on human impedance parameters, projecting human variable impedance parameters onto the teleoperated robotic arm to meet the interaction requirements of lunar construction tasks. This method integrates four-channel surface electromyography signals with an upper limb muscle mechanics model to construct a real-time identification system for human end-effector stiffness. Unlike traditional measurement methods, this study addresses the generalization issue of human-like variable impedance by combining personalized human physical parameters to enhance generalization capabilities. Additionally, in remote-operated variable impedance control, force feedback and visual feedback are used to enhance information transparency during human-machine interaction and trigger natural neural reflexes in the human body to adaptively adjust impedance. Finally, based on the assembly task requirements of a lunar truss construction platform, the study validated that humanoid variable impedance remote operation exhibits superior performance distinct from traditional remote operation.

High-precision orbit synthesis of two-line elements based on Long Short-Term Memory network

, Available online , doi: 10.11728/cjss2025-0093

Abstract(174) PDF 1816KB(7)

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To enhance the accuracy of TLE (Two-Line Element) in orbit prediction and address the issues of traditional polynomial fitting and physical modeling methods in dealing with the nonlinear evolution trend of orbits, a high-precision TLE orbit parameter fitting method based on Long Short-Term Memory (LSTM) networks is proposed. This method utilizes historical TLE data to conduct high-precision time series fitting and orbit synthesis of orbital elements. By applying LSTM neural networks to model the time series of TLE orbit parameters and combining it with polynomial fitting, a hybrid modeling strategy is formed. The experiment constructs a fitting model using the TLE data of 87 Iridium 33 debris and generates synthetic TLEs, using the SGP4 propagator to forward propagate the orbit position errors for three days. The experimental results show that the propagation error of the synthetic TLE is significantly reduced compared to the original TLE within three days, with an improvement rate of 97.70% on the third day; the propagation error of most targets is controlled within 2 km. The error of synthetic TLEs is concentrated and stable; the error frequency statistics show that the coverage ratio of the 0-2 km error range within three days exceeds 81%, which is significantly better than the original TLE. The TLE orbit synthesis method based on LSTM demonstrates superior performance in capturing the nonlinear evolution of orbit parameters. Combined with angle linearization and smoothing filtering strategies, it significantly improves the accuracy and stability of orbit parameter fitting. The research results have certain application value in enhancing space situational awareness, orbit collision warning, and mission scheduling.

A Wide Temperature Range Sodium Solid State Battery Resistant to Extreme Environments for Deep Space Exploration

, Available online , doi: 10.11728/cjss2025-0075

Abstract(141) PDF 1402KB(6)

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To meet the urgent demand for wide-temperature-range adaptability and high safety of energy systems in extreme environments such as deep space exploration, a novel organic-inorganic composite sodium solid electrolyte was designed and prepared in this paper for the construction of high-performance sodium solid-state batteries. Lead methylammonium chloride (MAPbCl₃) with a perovskite structure was used as an inorganic ion conductor, combined with sodium alginate (SA) and multifunctional polymer ETPTA, and a stable and dense composite polymer network was formed through in-situ ultraviolet light-initiated polymerization. This composite electrolyte has a high ionic conductivity of 5.65×10⁻⁴ S·cm⁻¹ and excellent Na⁺ transference number of 0.65 at room temperature, and still maintains stable performance at -20℃. In the assembled NVP | MSE | Na all-solid-state battery, the capacity retention rate is 68.4% after 200 cycles at room temperature and 69.6% after 100 cycles at -20℃, which is significantly better than the traditional physical dispersion system. The research results show that the constructed composite structure has good interface stability and cycling performance at extreme temperatures, providing key material support for future energy storage systems for polar observation and deep space exploration.

Case study of the ionospheric irregularities in China low latitude during the geomagnetic storm in July 13-14, 2013

, Available online , doi: 10.11728/cjss2025-0128

Abstract(313) PDF 1872KB(10)

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This study investigates the effects of a moderate geomagnetic storm during July 13-14, 2013 on the development of ionospheric irregularities in the low latitude region of China. Although in the East Asian sector, ionospheric irregularities are relatively uncommon in July, unseasonal irregularities are observed during this geomagnetic storm. Ground-based GNSS data from Crustal Movement Observation Network of China (CMONOC) and Hong Kong Satellite positioning Reference stations (SatRef), S4 index data from the ionospheric scintillation monitor (ISM) at Shenzhen (22.59°N, 113.97°E) station, ionosonde data from Fuke (19.4°N, 109.0°E) station, and geomagnetic data are used in this study to show the evolution of the ionospheric irregularities in the low latitude region of China during the geomagnetic storm. Geomagnetic and solar activity parameters are used to analyze the generation mechanisms of the irregularities. It is shown that the eastward electric field enhanced by the geomagnetic storm is the major factor contributing to the generation of the irregularities. Satellite traces in the ionograms before the onset of the irregularities indicate that large-scale wave structures acting as seed perturbations may also contribute to this event. Furthermore, it is found that the temporal distribution of S4 index and ROTI are generally similar (enhanced during 15:00-18:00 UT) and coincide with the time range of the irregularities, but the distribution of L2 loss of lock is slightly different (occurring around 14:00 UT, about one hour earlier). These loss of lock occurrences are unrelated to this event.

Validation and Analysis of Discrepancy Causes for Wave Slope Variance Based on Satellite Remote Sensing

, Available online , doi: 10.11728/cjss2025-0076

Abstract(189) PDF 1486KB(7)

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The Mean Square Slope (MSS) of the sea surface is a key parameter for characterizing sea surface roughness in the field of marine microwave remote sensing, and it is of great significance for studying the air-sea coupling process and marine meteorological monitoring. This paper conducts a comparative analysis of the MSS retrieved by the Surface Waves Investigation and Monitoring (SWIM) on the China-France Oceanography Satellite (CFOSAT) and the Cyclone Global Navigation Satellite System (CYGNSS). SWIM retrieves the MSS by fitting the two-dimensional normalized radar backscatter cross-section under different incident angles and azimuth angles. CYGNSS obtains the MSS caused by local winds by subtracting a correction amount on the basis of preliminary observations. In this paper, after collocating the data from SWIM and CYGNSS in January 2023, a direct comparison has been made. It is found that the MSS derived from SWIM is higher than that retrieved by CYGNSS under low wind speeds, while when the wind speed exceeds approximately 7 m/s, the MSS derived from CYGNSS is higher than the that given by SWIM. This is mainly attributed to the differences in the microwave bands of the two and the correction amount of the MSS generated by swell subtracted during the retrieval process of CYGNSS. After correcting the SWIM MSS using the Elfouhaily spectrum model, the bias between the two is approximately 0.03, and the random root mean square error is 0.0323. This error is caused by the MSS generated by swell and the differences in the cutoff wavelength. The research results clarify the differences and error sources of the MSS retrieved by the two spaceborne sensors, providing an important reference for the calibration of MSS data and subsequent marine research and applications.

, Available online , doi: 10.11728/cjss2025-0081

Abstract(169) PDF 1040KB(11)

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A Cold Optical Design of a 10 THz Focal Plane Imaging System for the Space Applications

, Available online , doi: 10.11728/cjss2025-0088

Abstract(146) PDF 1348KB(4)

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In passive space exploration, the target signals are typically extremely weak and the detection system needs to achieve high sensitivity and low noise requirements. To satisfy these demands, cold optics has become indispensable. This method integrates optical components (such as lenses and mirrors) into cryogenic environments and combining them with cryogenic detectors to achieve the detection needs. However, conventional optical design faces constraints due to the limited cooling capacity of spaceborne instruments. The research presents a cold optical model based on multi-reflection and optimizes the window size design according to this model. A design for a 10 THz focal-plane array imaging system, employing pulse-tube coupled with J-T refrigeration for space application was proposed. The thermal leakage of the system is evaluated analytically, and a cold optical experiment validates the theoretical model, demonstrating strong agreement between the predicted result and the experimental result.

A short-term forecasting method of foF2 in the ionosphere over the Chinese region based on deep learning

, Available online , doi: 10.11728/cjss2025-0073

Abstract(233) PDF 3213KB(16)

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As a key parameter of the ionosphere, the critical frequency of the F2 layer of the ionosphere (foF2) is of great significance for ensuring the stable operation of systems such as high-frequency radar and short-wave communication. This paper proposes a short-term forecasting method for the ionospheric foF2 based on deep learning. By using the Bidirectional long short-term memory model with attention mechanism (BiLSTM-Attention) algorithm and combining the observed values of the ionospheric foF2 at the ionosonde station for the previous 7 days, universal time, solar activity index, and geomagnetic activity index as inputs, the forecasting of the ionospheric foF2 in the Chinese region is realized. The results of the comparative analysis of the model show that: 1) The forecasting error of the low-latitude stations is significantly higher than that of the mid-latitude stations. The BiLSTM-Attention model performs the best, followed by the long short-term memory network (LSTM) model. Compared with the International Reference Ionosphere model (IRI), the root mean square error (RMSE) of the BiLSTM-Attention model is reduced by 54%, the mean absolute error (MAE) is reduced by 57%, and the coefficient of determination (R2) is increased by 28%. 2) During geomagnetic storms, the BiLSTM-Attention model successfully captures the negative storm effect of the ionosphere in the Chinese region (the decrease of foF2), which is in good agreement with the observed values, while the IRI model cannot represent the significant deviation caused by the disturbance. Although the IRI model is overall close to the vertical sounding observations during the geomagnetically quiet period, there are still systematic errors in the periods after sunset and at night. 3) As the forecasting time increases from 1 hour to 24 hours, the forecasting error of the model shows a systematic upward trend, with the RMSE increasing from 1.02 MHz to 2.03 MHz and the MAE increasing from 0.71 MHz to 1.55 MHz. Relevant research provides high-precision ionospheric parameter forecasting support for space weather warning and short-wave communication system optimization.

, Available online , doi: 10.11728/cjss2025-0055

Abstract(172) PDF 1721KB(7)

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The performance of the fluxgate sensor in open-loop measurement mode as a function of temperature was investigated. To avoid the mutual coupling effects between the circuit and the sensor during the closed-loop signal processing of the fluxgate, an open-loop magnetic field measurement system for the fluxgate was developed, the results of which directly reflect the intrinsic physical properties of the fluxgate sensor. Based on the characteristics of different performance parameters of the fluxgate sensor, a temperature cycling test in a non-magnetic environment was designed and conducted within the temperature range of -40°C to +80°C. The test results showed that the offset drift of the fluxgate sensor did not exceed ±1.5 nT, the amplitude of signal phase drift reached 60°, the open-loop gain changed by approximately ±5%, and the noise varied between 4 pT/√Hz and 7 pT/√Hz@1Hz. It can be seen that, except for the phase characteristics of the sensor signal, the fluxgate sensor exhibits excellent temperature stability. In the closed-loop control circuit of a sensor, the phase-sensitive demodulation link is highly sensitive to signal phase. Significant phase drift is the main factor causing the temperature drift of the fluxgate magnetometer.

Simulation and experimental study on the influence of cables on the performance of Search Coil magnetometers

, Available online , doi: 10.11728/cjss2025-0037

Abstract(169) PDF 2564KB(13)

Abstract:
The length of the cable between the search coil and the preamplifier circuit has a significant impact on signal transmission. This study conducts a multidisciplinary simulation analysis and experimental verification on search coil magnetometer with long-distance cables. Based on search coil magnetometer prototype targeting a frequency bandwidth of 10Hz-1kHz and a noise level of 30fT/√Hz@1kHz, this study conducts research and establishes a circuit-principle model of the search coil-cable-preamplifier circuit. The role of the cable in search coil magnetometer based on transimpedance preamplifier circuit is analyzed, and theoretical simulation is carried out. The influence of cable length variation on sensitivity and noise frequency distribution is verified through experiments, and the results are basically consistent with the theoretical model, indicating that although the increase in cable length has a significant impact on search coil magnetometer, it can be designed and predicted through theoretical models. An increase in cable length reduces low-frequency sensitivity and low-frequency noise level, but it also significantly raises the level of high-frequency noise. It has little effect on magnetic wave detection at low-frequency, but substantially degrades magnetic field detection performance at high-frequency. For the target search coil, even if the cable length reaches 50 meters, it demonstrates satisfactory response and low noise levels within the 10 Hz–1 kHz frequency band, meeting the requirement of 30fT/√Hz@1kHz.

Scientific achievements of China's Chang'e project: a bibliometrics-based approach

, Available online , doi: 10.11728/cjss2025-0029

Abstract(217) PDF 2265KB(10)

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As an integral component of China’s broader national strategy for deep space exploration, the Chang'e Project has garnered considerable attention from the global academic community. Based on the Web of Science database, this study employs bibliometric methods to quantitatively analyze the number of publications related to the Chang'e Project, their distribution across various disciplines and journals, the competition and cooperation among major countries and institutions, and the trend of scientific outcomes from the Chang'e-1 to Chang'e-5 missions for each scientific payload. We quantify the influence of the Chang'e Project and its contribution to lunar scientific research, and present the following status and trends: (1) the Chang'e Project has propelled China's lunar science research towards the international frontier, with the research team undergoing rapid expansion; (2) the contribution of Chinese scientists to lunar science mainly comes from the in situ exploration of the farside by the Chang'e-4 mission and the analyses of returned samples by the Chang'e-5 mission; and (3) the future breakthroughs in China's lunar science will emerge from the in situ exploration of new regions and the research of new samples. The results of this study will provide important references for China's future strategic planning of deep space exploration and the development of planetary science.

Study on the Effects of Planet Radius on Long-term Evolution of Oxygen Ion Escape Rate in Venus-like Exoplanets

, Available online , doi: 10.11728/cjss2025-0090

Abstract(180) PDF 1077KB(15)

Abstract:
In recent years, the study of exoplanets has become a hot topic in astronomy and planetary science. With the rapid development of detection technology, mankind has discovered and confirmed thousands of exoplanets, and has carried out in-depth studies on the atmospheric composition, orbital properties, habitability and other key characteristics of these exoplanets. In this context, star-planet atmosphere interactions have been recognized as one of the central mechanisms affecting the evolution of planetary atmospheres and their habitability. In this study, we aim to reveal the role of planetary radii in the long-term evolution of their atmospheric escape. By building a three-dimensional magnetohydrodynamic (MHD) model and combining it with the evolutionary characteristics of the stellar system, we reveal the role of planetary radii in the long-term evolution, and construct a numerical simulation system based on the Venus-like atmospheric escape model, taking Kepler-1649 c and its host star as the research objects, which covers different planetary radii and stellar ages. It is found that the planetary radius significantly changes the escape contribution ratio of each ion. Among them, the escape rate of O⁺ as a proportion of the total escape rate decreases with increasing planetary radius, from 99.3% to 17.1% at 4.8 Gyr. Meanwhile, the variability between the O⁺ ion distribution and the total ion distribution in interplanetary space increases with radius. This study provides a new perspective for understanding the mechanism of exoplanet atmospheric evolution by discovering the differential effect of planetary radius on the escape behavior of different ions.

Maximum A-posteriori Probability Decoding Algorithm for the Punctured CCSDS Convolutional Codes

, Available online , doi: 10.11728/cjss2025-0058

Abstract(154) PDF 1242KB(4)

Abstract:
The punctured CCSDS convolutional codes suffered a bit-error-rate performance degradation using the Viterbi decoding algorithm. Aiming at this issue, this paper proposed a max a-posteriori probability decoding algorithm for these codes, it takes a forward and backward update progress of the likelihood messages based on the trellis graph, to obtain the maximum a-posteriori log-likelihood ratio for the corresponding input bits, thus to improve the performance of the punctured convolutional code. As showed by the simulation results, the punctured CCSDS convolutional codes could get an even lower bit-error-rate by using the proposed algorithm, and the higher the code rate, the more significant the bit error rate reduction. Compared with the Viterbi decoding algorithm, the proposed decoding algorithm has a coding gain about 0.2dB and 0.6dB for code rate 5/6 and 7/8 respectively.

, Available online , doi: 10.11728/cjss2025-0046

Abstract(206) PDF 2090KB(15)

Abstract:
Equatorial Plasma Bubbles (EPBs) are cavity structures with low electron density formed in the low-latitude ionosphere after sunset. Their evolution process can lead to the scintillation and attenuation of radio signals. Precise prediction of the evolution of Equatorial Plasma Bubbles is of great significance in the fields of space weather research and satellite communication. This paper proposes an EPB evolution prediction model based on the SimVP (Simpler yet Better Video Prediction) framework. By learning the spatiotemporal evolution characteristics of EPBs from historical airglow image data, it achieves accurate prediction of future evolution. Through systematic experimental analysis of the influence of key parameters on the model performance, the results show that when the time resolution is set to 3 minutes and the architecture with 6 input frames and 6 output frames is adopted, the model performs optimally (SSIM = 0.989, PNSR = 34.704). The complexity of the spatial morphology of EPBs has a significant impact on the prediction accuracy, while the interference of light pollution is relatively limited. This model not only provides a data-driven and efficient prediction tool for the evolution of EPBs, but also offers technical support for the restoration of contaminated airglow observation data.

, Available online , doi: 10.11728/cjss2025-0018

Abstract(278) PDF 1834KB(22)

Abstract:
Frequency resources are one of the strategic resources supporting the development of the aerospace industry and have non-renewable properties. With the development and utilization of the Moon becoming an international hotspot gradually, the demand users for frequency resources in the cislunar space is shifting from a small number of exploratory tasks related to space research to large-scale and serialized deployment tasks such as the construction of space infrastructure, in-situ resource development and utilization, and manned/unmanned lunar landings and stays. However, under the existing international regulatory framework, the frequency resources available for large-scale lunar development and utilization tasks are extremely limited, and the contradiction between supply and demand is becoming increasingly acute. Based on analysis of advance publication information or notification information of frequency resources for cislunar space stations, as well as the planning and on-orbit exploration mission, this paper summarizes current state and development trend of cislunar frequency resources. By simulation on self-developed software, quantitative interference calculation and analysis were performed on typical international tasks. Frequency utilization recommendations for future cislunar satellite missions are proposed, providing advice for frequency design of cislunar mission.

Ka-band spaceborne Doppler scattering measurement and echoed Doppler centroid estimation of sea surface

, Available online , doi: 10.11728/cjss2025-0072

Abstract(170) PDF 1533KB(28)

Abstract:
As an important part of the earth system, the ocean surface dynamic parameters (wind, wave, current) have an important impact on air-sea interaction, ocean material and energy balance and climate change. Under the condition of spaceborne measurement, the amplitude and phase of echo contain the relevant motion information of the sea surface, which is necessary to study the Doppler spectrum characteristics formed by the high operating speed of the satellite and the sea surface dynamic parameters under the on-board condition. In this paper, a time-varying dynamic sea surface model including the main ocean dynamic parameters wind, wave and current is established by using the existing linear random superposition theory to simulate the ocean surface. Then, the backscatter coefficients of the sea surface under Bragg scattering are calculated, and their reliability is verified based on the measured data. For the study of Doppler characteristics based on Bragg scattering of moving sea surface, this paper uses the formulated OSCOM satellite parameters and sea states to obtain the Doppler spectrum including the influence of different wind parameters under the condition of Bragg scattering at medium incidence angle, and analyzes the Doppler spectrum characteristics under the influence of wind speed, wind direction, wind fetch through the spectral parameter estimation method. The analysis results of wind speeds show that the sea surface roughness and root mean square height increase with the wind speeds, resulting in the stronger backscatter modulation, and the shift and broadening of the Doppler center increase accordingly. The results of wind direction analysis show that the Doppler centroid of Doppler spectrum with wind direction is slightly asymmetric at the downwind and upwind, and reaches the minimum at 90 ° wind direction. The analysis results of the wind fetch show that when the wind speed is 10m/s and the length of wind fetch grows from a-10km-developing wave to a fully developed wave, the velocity of the sea surface increases, and the tilt modulation of the long wave increases, resulting in the Doppler shift increases, and the estimated Doppler centroid difference is 0.56m/s. Finally, the study considers the contribution of breaking wave to the co-polarized backscatter, and analyzes the influence of both on Doppler centroid and velocity estimation. The echo Doppler spectrum analysis under the condition of wave breaking shows that when the wind speed is 12m/s and the observation azimuth is the same as the wind direction, the contribution of breaking wave to Ka-band backscatter coefficient is about 4dB. Compared with the case without considering the breaking wave, the Doppler centroid offset is about 95.2Hz, resulting in a deviation of about 0.4m/s for the radial velocity estimation.

Retrieval of the Imaginary Dielectric Constant in Mountain Glaciers Using Airborne Radar and the Dual Rough Interface Numerical Simulation Model

, Available online , doi: 10.11728/cjss2025-0052

Abstract(170) PDF 1978KB(1)

Abstract:
As a key indicator of global climate change and an essential freshwater resource, the accurate acquisition of multiple physical parameters of glaciers holds significant importance for global climate change research, ecological conservation, and water resource planning. In China, glaciers are predominantly mountain glaciers distributed in high-altitude regions. Constrained by harsh environments and complex terrain, traditional in-situ detection methods fail to achieve large-scale continuous monitoring of internal glacier parameters. Satellite-borne glacier remote sensing, meanwhile, faces limitations in resolution and interference from complex ground clutter in mountainous glacier regions, and thus has yet to be operationalized. Airborne radar, with its superior spatial resolution and flexible detection capabilities, has become a critical technical tool for glacier monitoring and research. However, airborne detection of mountain glaciers still confronts challenges posed by undulating ice surfaces and complex subglacial topography: scattering clutter from the uneven ice surface interferes with radar signal interpretation and precise inversion of key parameters, while the intricate subglacial structure and scattering losses caused by ice surface topography interact with dielectric losses within the ice, impeding accurate inversion of glacier dielectric constants. To address these challenges, this study integrates airborne ultra-wideband radar detection data from mountain glaciers with the Pseudo-spectral Time Domain (PSTD) numerical simulation method. A coupled model of ice surface-subglacial dual interface topography and dielectric parameters is established. Through two-dimensional PSTD electromagnetic simulations, the interaction mechanism between topographic scattering and ice dielectric loss is elucidated. Furthermore, an inversion method for the imaginary part of the ice layer dielectric constant in measured regions is proposed based on dynamic range analysis. For the measured data from Laohugou Glacier No. 12, iterative optimization converges the estimated imaginary part value to 6.0×10⁻⁴, with a dynamic range difference of 0.61% from the measured mean value. The relative error between the estimated imaginary part and the theoretical mean is 21%. Cross-validation between simulation results and theoretical models demonstrates that this method effectively improves the inversion accuracy of glacier dielectric parameters in complex terrain by decoupling the synergistic interference between topographic relief and dielectric parameters, thereby offering a viable solution for studying internal dielectric properties of glaciers.

, Available online , doi: 10.11728/cjss2025-0003

Abstract(189) PDF 1886KB(6)

Abstract:
Aiming at the single star simulator can only simulate one stellar target at a time, in order to solve the problems of manually replacing the star point plate when simulating other stars, low efficiency of calibration, poor consistency of the optical axis, etc. We design a single-star simulator multi-star point automatic replacement device. First, based on the working principle of off-axis reflective single star simulator, a rotating wheel type multi-star point automatic replacement device is proposed, according to the theory and design requirements of the stellar simulator to determine the size of the star point plate micro-aperture, to design the mounting and adjustment structure of the star point plate, to adjust the consistency of the star point micro-aperture with the optical axis of the optical system, and to carry out the finite element analysis and optimisation of the star point disc with the goal of light weighting. Circularity, the sources of stray light transmission are analysed and suppression measures are summarised, and a stray light cancellation structure is designed to reduce the impact on the magnitude simulation. Finally, the design of the electronic control system to achieve the automatic switching of the star point plate and the precision analysis of the error source of the influence. The results show: the single star point tensor angle error is better than 1.2″, and the optical axis consistency of the star point position is better than 10μm, which meets the accuracy requirements of the single star tensor angle and the star point position of the single-star simulator when simulating different stellar targets, and improves the efficiency of the checking and simulation accuracy of the simulation of different stellar targets.

Multi-Parameter Solar Wind Prediction Based on Deep Learning

, Available online , doi: 10.11728/cjss2025-0022

Abstract(240) PDF 2017KB(23)

Abstract:
When interacting with the Earth's magnetosphere, high-speed plasma flows in the solar wind can trigger space weather events such as geomagnetic storms. Therefore, accurately forecasting solar wind parameters is critical for early warnings of space weather and the stable operation of modern technological systems. This study employs TimeXer, a deep learning model incorporating patch embedding and cross-attention mechanism, to explore the complex dependencies among solar wind speed, dynamic pressure, proton density, and proton temperature. This model can accurately predict solar wind parameters for the next 72 hours by only using historical solar wind data and time information, and it is also interpretable. Test results during low solar activity level (2021) and high solar activity level (2024) periods demonstrate: (1) TimeXer's root mean square errors (RMSE) for solar wind speed, dynamic pressure, proton density, and proton temperature are 68.39 km/s, 2.12 nPa, 5.02 N/cm³, and 8.83×10⁴ K, respectively, while the mean absolute errors (MAE) are 47.65 km/s, 1.00 nPa, 3.13 N/cm³, and 4.49×10⁴ K. Compared with traditional and advanced deep learning methods, TimeXer exhibits superior performance, even can accurately capture the overall variation trends of solar wind parameters during geomagnetic storm. (2) Optimal prediction performance is achieved with a historical input length of 336 hours (corresponding to the solar wind's ~14-day quasi-period). (3) The joint modeling prediction based on the inter-parameter dependencies of solar wind parameters is significantly better than the single-parameter prediction. (4) Cross-attention weight analysis reveals that the four solar wind parameters contribute similarly to proton temperature and solar wind speed predictions. The solar wind speed and proton temperature contribute more to the prediction of proton density, while the proton temperature, solar wind speed, and annual time information have a more substantial influence on the prediction of solar wind dynamic pressure. Moreover, the importance of time information grows with increasing scales of time information.

Single Event Upsets Fault Tolerance of Convolutional Neural Networks Based on Adaptive Boosting

, Available online , doi: 10.11728/cjss2025-0025

Abstract(176) PDF 1530KB(10)

Abstract:
Single-event upsets in the space radiation environment pose a serious threat to the reliability of satellite-borne intelligent systems. Traditional fault-tolerance methods such as triple modular redundancy and periodic scrubbing face issues like high resource overhead and power consumption. This paper proposes a lightweight fault-tolerance method based on an adaptive boosting algorithm (AB-FTM), which constructs a heterogeneous ensemble architecture of ResNet20/32/44 weak models. While reducing the parameter scale by 18.2% compared to the original ResNet110, it improves classification accuracy and robustness through a dynamic weight adjustment mechanism. Experimental validation on datasets including CIFAR-10, MNIST, and EuroSAT shows that when 0.0004% of parameters experience single-event upsets, the proposed method improves accuracy by 20.39%, 26.25%, and 21.02% respectively compared to the ResNet110 baseline model, significantly outperforming existing fault-tolerance solutions. This method provides a new solution for future space science satellites using satellite-borne intelligent systems that balances reliability, lightweight design, and computational efficiency.

Dynamic Channelization Design Method for Space-based Spectrum Sensing

, Available online , doi: 10.11728/cjss2025-0026

Abstract(249) PDF 2100KB(10)

Abstract:
Dynamic channelization technology, a key technology for realizing space-based broadband spectrum sensing, possesses the capability of real-time decomposition and parallel processing of broadband signals, which can alleviate the computational and processing pressure on onboard resources. To address the cross-channel issues in broadband channels, this paper employs a polyphase filter bank with perfect reconstruction characteristics to establish an analysis-synthesis joint processing system, and proposes a joint time-frequency domain cross-channel decision algorithm based on an optimized adaptive threshold constant false alarm detection (Optimized-CFAR), achieving adaptive fusion and accurate reconstruction of cross-channel signals. Simulation results demonstrate that the detection probability reaches 98.6% at a signal-to-noise ratio (SNR) of 15 dB, with the amplitude distortion of the reconstructed signal being approximately 0.0048 dB and the reconstruction fidelity achieving 0.972. The FPGA implementation complexity of the proposed algorithm is reduced by 13.2% compared to existing advanced schemes.

Analysis of Synchronized Developmental Conditions for Caenorhabditis elegans Suitable for Microfluidic Chip Loading

, Available online , doi: 10.11728/cjss2025-0008

Abstract(214) PDF 1159KB(9)

Abstract:
With the progressive shift of space biological experiments from post-flight observations following short-term missions to long-term in-orbit observations, coupled with the increasing frequency of extravehicular activities by astronauts, the study of biological damage induced by the external space environment has emerged as a pressing and pivotal direction in the field of space life sciences. To achieve long-term in-orbit observation of individual nematode development in the extravehicular environment, it is necessary to prepare samples that meet the requirements of the microfluidic chip system used for nematode encapsulation, ensuring compatibility with the chip's loading specifications. The nematode chip regulates the entry of individual nematodes into the cultivation chambers through the precise dimensions of its microchannels. Consequently, the developmental stage of the samples must meet exacting criteria, which are directly correlated with the nematode's body width (requiring a body width range of 24~29 μm). To analyze the loading and developmental conditions of nematodes responsive to radiation and microgravity, thereby enhancing the sample loading efficiency of various nematode strains in microfluidic chips on the future Chinese Space Station, this study establishes a standardized operational protocol and verification method for the preparation, propagation, and post-synchronization developmental timing confirmation of nematode samples for microfluidic chip applications. The incineration method was employed to measure the body width of various nematode strains under different propagation and development periods, aiming to ascertain the optimal propagation time and the most suitable developmental stage for each nematode strain. The experimental results revealed the following findings: the wild-type strain exhibited a body width ranging from 25.41~26.41 μm after 3 weeks of propagation and 104-110 hours of development; the AM141 strain displayed a body width of 20.26 μm after 3 weeks of propagation and 96 hours of development; the SSM264 strain showed a body width of 23.51 μm after 4 weeks of propagation and 144 hours of development; and the TG11 strain demonstrated a body width of 26.16 μm under the same conditions of 4 weeks of propagation and 144 hours of development. These measurements meet the requirements for chip loading. By confirming the sample conditions before and after loading into the microfluidic chip, it was determined that the body width range of the samples from the four strains added to the chip was 27.71~28.02 μm, thereby verifying the validity of the samples.

Research on Key Performance Test Methods of Digital Subsystem of Marine Salinity Satellite Integrated Aperture Radiometer

, Available online , doi: 10.11728/cjss2025-0014

Abstract(231) PDF 1046KB(8)

Abstract:
The digital subsystem of the first spaceborne L-band one-dimensional synthetic aperture radiometer of China adopts a distributed structure, consisting of multiple independent, parallel working distributed front-end data acquisition units, integrated digital units, and synchronization units. The key performance of the subsystem includes phase consistency and amplitude consistency of all intermediate frequency AD acquisition channels of the distributed front-end data acquisition units. The subsystem performance tests aim at independent hardware performance and the whole digital subsystem performance. The testing of distributed front-end data acquisition units for hardware performance utilizes the synchronization pulse within the digital subsystem as a trigger signal to obtain the raw acquisition sequences of all AD channels simultaneously. The performance of the whole digital subsystem is measured by extracting the cross-correlation and auto-correlation information from the scientific data packets for processing. The ground prototype testing obtained the phase consistency of multi-channels under 1°, amplitude consistency under 0.4dB, and correlation offset under -35dB, which reaches to the instrument index requirements and also proves the correctness of the testing method.

Design and Implementation of a High-Performance Image Compression Core for Spaceborne Applications

, Available online , doi: 10.11728/cjss2025-0021

Abstract(187) PDF 1545KB(7)

Abstract:
To address the critical need for efficient image storage and transmission in aerospace applications, this study presents a CCSDS 122.0-B-1-compliant compression core implemented on FPGA. The design incorporates innovative encoding control logic and optimized data organization through co-optimization of algorithmic features and hardware constraints. A segment-based architecture with 256-pixel blocks achieves superior compression efficiency among existing solutions, while effectively containing error propagation through segmented compression. The architecture further enables continuous quality adaptation and progressive image transmission. To resolve performance bottlenecks in scanning and encoding processes, we developed fully parallelized scanning with adaptive parallel encoding, demonstrating 50% efficiency improvement in validation tests. Supporting images up to 4096×4096 pixels with 16-bit depth, the core delivers 90.64 Msamples/s throughput, meeting operational requirements for diverse space missions.

, Available online , doi: 10.11728/cjss2025-0035

Abstract(192) PDF 1529KB(3)

Abstract:
Polar Mesospheric Clouds (PMCs), as ice crystal clouds formed in the middle and upper atmosphere (approximately 83 km), have a seasonal onset that serves as an important parameter for studying the coupling processes between thermodynamics and dynamics in the polar mesosphere. This paper, based on multi-source observational data from 1979 to 2023, systematically analyzes the long-term evolution characteristics of the onset of PMCs in both hemispheres and examines its correlations with the reversal time of stratospheric zonal mean wind and solar activity. The results show that there are significant differences in the onset of PMCs between the two hemispheres: the interannual variation (with a standard deviation of 22 days) in the southern hemisphere is about twice that in the northern hemisphere (11 days), which may be related to differences in thermal and dynamic processes such as inter-hemispheric circulation modes and the intensity of gravity wave activity. In the southern hemisphere, the onset of PMCs season exhibits a very strong positive correlation with the reversal time of the stratospheric zonal mean wind, while in the northern hemisphere, although a negative correlation is observed, the approximately 60-day difference does not directly indicate a causal relationship between the two. The regulation of the onset by solar activity (Lyman-α radiation) also shows hemispheric asymmetry. In the northern hemisphere, there was a certain negative correlation with solar activity before 2011 that later weakened due to changes in the stratospheric dynamic background, whereas the southern hemisphere exhibited only a weak response. This indicates that both solar radiation effects and dynamic processes may jointly contribute. In addition, the discrepancies among multi-source data suggest that differences in detection systems and data types can introduce uncertainties in studies of the long-term variation characteristics of PMCs.

New Method and Accuracy Analysis for Medium and Long-term Prediction of BDS-3 Orbit

, Available online , doi: 10.11728/cjss2025-0020

Abstract(369) PDF 2520KB(33)

Abstract:
Long-term orbit prediction serves as an effective method to suppress the overall rotation of the inertial frame in autonomous navigation of satellite navigation systems, and the main factor influencing the accuracy of long-term orbit prediction is the uncertainty associated with the solar radiation pressure perturbation model. This paper proposes a method of modeling and updating the ECOM-5 solar radiation pressure model parameters for long-term orbit prediction, and evaluates its performance by fully using the correlation between the solar radiation pressure coefficient and the solar altitude angle. Taking 24 Medium Earth Orbit (MEO) satellites and 2 Inclined Geosynchronous Orbit (IGSO) satellites of the Beidou-3 global navigation satellite system (BDS-3) as an example, 18 groups of 90 days’ orbits were predicted from 2022/01/01 to 2023/06/01. And then the precise ephemeris of Center for Orbit Determination in Europe (CODE) was used as the reference orbit to evaluate the performance of long-term orbit prediction. The experiments results indicate that adopting the new orbit prediction method proposed in this paper for 90 days’ orbit prediction of navigation satellites, for MEO satellites, the average Root Mean Square (RMS) of the three-dimensional position error on the 30^th day, 60^th day, 90^th day is approximately 200m, 700m, and 1.4km, respectively, and that of the average URE RMS of the orbit is 18.79m, 61.43m, and 124.00m, respectively; The RMS mean values of the orbital inclination angle i are 6.07mas, 9.76mas, and 12.38mas, respectively, and those of the right ascension of the ascending node Ω are 6.47mas, 11.24mas, and 14.88mas, respectively; For IGSO satellites, the three-dimensional position error of the forecast orbit is one order of magnitude lower than that of MEO satellites, while the prediction errors of i and Ω are comparable to those of MEO satellites. Therefore, it can be concluded that the method in this paper exhibits high accuracy in predicting long-term orbital positions and orbital orientation parameters i and Ω, which is expected to provide essential support for mitigating the overall rotation of autonomous navigation of navigation satellite constellations.

Error analysis of HASDM using SWARM satellite data

, Available online , doi: 10.11728/cjss2025-0012

Abstract(271) PDF 1933KB(30)

Abstract:
Based on the atmospheric thermospheric density data inverted by the accelerometers of the SWARM-B and SWARM-C satellites, the error characteristics of the HASDM model were comprehensively analyzed, covering the influence of multi-dimensional factors such as solar activity level, geomagnetic activity level, latitude, local time and altitude. The study found that HASDM showed good performance under high solar activity and enhanced geomagnetic activity conditions, with small errors and high stability, while it was easy to overestimate density under low solar activity and low geomagnetic activity levels; the latitude distribution showed that HASDM mainly showed an underestimation trend in the high latitudes of the North and South Poles, and an overestimation trend near the equator; the local time analysis showed that HASDM could accurately capture the peak and valley changes, but the overestimation phenomenon was more obvious in specific periods such as 3-5 local time and 19-21 local time; the altitude analysis showed that the orbit was elevated, the relative error was small, but the instability increased. The research results provide an important basis for further optimizing the performance of the HASDM model and improving its adaptability in complex space environments.

On-orbit identification and compensation for deformation errors of the solar observation system

, Available online , doi: 10.11728/cjss2025-0016

Abstract(140) PDF 791KB(1)

Abstract:
Aiming at the problem of optical axis pointing deviation caused by the internal deformation errors of the satellite's solar observation system, an on-orbit identification and compensation method for the deformation errors is proposed. Firstly, the mathematical modeling for the light path transfer process of the solar observation system is established. Secondly, the on-orbit identification and compensation method for the deformation error parameters in the mathematical model are given. Finally, the identification and compensation methods are simulated by mathematical simulation. The compensation effect is evaluated with the optical axis pointing accuracy as the evaluation standard. The simulation results show that the pointing accuracy of the solar observation payload's optical axis is improved by two orders of magnitude before and after the on-orbit compensation for the deformation error, which verifies the effectiveness of the proposed method. The results can be used as a reference for other payloads with two-dimensional adjustment mechanism.

High Wind Speed Correction for HY-2 Satellite microwave scatterometer based on Broad Learning System

, Available online , doi: 10.11728/cjss2025-0023

Abstract(216) PDF 1898KB(5)

Abstract:
To address the need for high wind speed correction of HY-2 series satellite microwave scatterometer, this study utilized the HY-2 wind speed of nine tropical cyclones between 2021 and 2022 as the data source. The Stepped Frequency Microwave Radiometer (SFMR) wind speed measurements served as the ground truth. A modeling dataset was constructed through spatiotemporal matching and randomly divided into a training set and a testing set at a 7:3 ratio. Subsequently, the Broad Learning System (BLS) was employed to do the regression analysis and develop a high-wind-speed correction model. Validation results demonstrate that the corrected HY-2 wind speeds achieved a root mean square error (RMSE) of 4.65 m/s, representing a 51% improvement compared to the uncorrected data. For wind speeds exceeding 25 m/s, the corrected RMSE and correlation coefficient reached 5.59 m/s and 0.68, respectively, marking significant enhancements over the original values of 13.69 m/s and 0.55. Additionally, a comparative analysis using Typhoon Chanthu (2021) as a case study revealed that the corrected HY-2C maximum wind speed increased from 22.09 m/s to 32.73 m/s. Further validation through wind speed profile comparisons confirmed the effectiveness of the proposed model.

, Available online , doi: 10.11728/cjss2025-0039

Abstract(208) PDF 911KB(11)

Abstract:
The responses of thermospheric winds at middle latitudes to the moderate geomagnetic storm of Mar 18-19, 2018, are examined using two ground-based Fabry-Perot Interferometer (FPI) observations from the Xinglong (XLON, 40.2°N, 117.6°E; magnetic latitude: 35°N) and the Sutherland Astronomical Observatory (SAAO, 32.2°S, 20.48°E; magnetic latitude: 40.7°S), combined with simulations from the Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIEGCM). The results reveal that the response of thermospheric winds to the geomagnetic storm is more pronounced in the Southern Hemisphere than in the Northern Hemisphere. Significant enhancements in equatorward and westward winds are observed at the SAAO station, with maximum meridional wind speeds reaching 128.4 m/s (equatorward) and maximum zonal wind speeds reaching -165.6 m/s (westward). Comparative analysis with TIEGCM simulations indicates that the model can reasonably reproduce the disturbance trends in observations, particularly in the variations of meridional winds at SAAO and zonal winds at XLON. However, certain quantitative discrepancies remain in the model's predictions: the model underestimates the eastward zonal winds at SAAO and overestimates the equatorward meridional winds at XLON.

A Review of Progress in Condensation and Heat Transfer Research in Microgravity

, Available online , doi: 10.11728/cjss2025-0028

Abstract(358) PDF 1206KB(9)

Abstract:
A comprehensive review of experimental and numerical studies of film and droplet condensation in microgravity is presented, covering in-tube and plane condensation as well as enhanced heat transfer mechanisms. For condensing heat transfer in tubes, gravity-independent criterion numbers (Bond number, Froude number, etc.) are used to determine whether gravity affects heat transfer, and the effect of gravity can be attenuated by increasing the mass flow rate of the vapor and reducing the tube diameter. For droplet condensation, continuous droplet condensation in microgravity can be achieved by increasing the vapor velocity, and using surfaces with a wetting gradient or micro/nano structure in combination with airflow purging to remove condensate droplets. Current research on condensation experiments in microgravity is limited, mainly due to the fact that long-term, continuous microgravity experimental are extremely rare. Emphasis should be placed on the Chinese Space Station and the International Space Station to carry out experimental studies of condensation heat transfer over long periods of time, to make up for the large amount of lack of reproducible experimental data, exploring the mechanism of gravity's effect on condensation heat transfer, in order to develop reliable design tools for space station applications.

Preliminary Analysis of Solar-Interplanetary Propagation of the Space Weather Event in May 2024

, Available online , doi: 10.11728/cjss2025-0024

Abstract(201) PDF 2209KB(15)

Abstract:
A variety of observations are employed to conduct a preliminary analysis of the propagation in solar-interplanetary space of seven earth-directed full-halo coronal mass ejections (CMEs) originated from the solar active region (AR) 3664 from May 8 to 11, 2024. These seven CMEs can be divided into two groups. The first group consists of four CMEs that occurred during the period from 05: 36 UT on May 8 to 9: 24 UT on May 9, and the second group consists of three CMEs that occurred during the period from 18: 52 UT on May 9 to 1: 36 UT on May 11. We utilize the heliospheric imager on the Solar Terrestrial Relations Observatory A (STEREO A/HI) to observe and track the time-elongation relationships of the high-density regions corresponding to these two groups of CMEs, and apply the fixed-Φ angle fitting method and the harmonic mean fitting method to calculate the most probable propagation directions and average radial velocities of these two groups of CMEs. The results show that the high-density regions associated with these two groups of CMEs are respectively aliased in the field of view of STEREO A/HI. The minimum errors of two group CMEs' arrival times near the Earth's orbit calculated from the fitting radial velocities are 0.5 hours and 3 hours respectively. These results indicate that during the solar-terrestrial propagation of these two groups of CMEs, the fast CMEs behind catch up with the slower CMEs ahead, thus, the two groups of CMEs form two complex ejecta and generate the extremely intense geomagnetic storm.

Video super-resolution method for spacecraft approaching asteroids

, Available online , doi: 10.11728/cjss2025-0002

Abstract(177) PDF 1254KB(8)

Abstract:
In the imaging process of approach detection, dynamic image sequences often have problems such as image blur and insufficient resolution due to platform movement and jitter. This paper studies the super-resolution of image sequences in the process of approach detection and proposes a video super-resolution method based on BasicVSR++. By introducing spatial and channel attention mechanisms to enhance the model's ability to extract detail features, combined with shared projection weights, multi-group mechanisms and sampling point modulation, the effect of the alignment module is improved. While improving the network feature extraction capability, it makes up for the shortcomings of regular convolution in long-distance dependency and adaptive spatial aggregation. At the same time, downsampling is combined with a low-pass filter to reduce the high-frequency components of the image, which improves the robustness of the model to slight image jitter. In addition, a new upsampling module is introduced to combine local and global features, generate an adaptive upsampling kernel to expand the receptive field, and better restore the global structure and reconstruct details. The simulation experimental results show that the proposed method improves the peak signal-to-noise ratio (PSNR) and structural similarity (SSIM) indicators by 2.2% and 2.1% respectively compared with the original method.

, Available online , doi: 10.11728/cjss2025-0009

Abstract(305) PDF 1988KB(26)

Abstract:
　　
　　Based on the Brewer ozone spectrophotometer long-term (1993-2023) observations at Zhongshan Station, Antarctica, atmospheric total ozone column (TOC) of the Merra2 and ERA5 reanalysis are compared, evaluated and their trends are analyzed The results show that the reanalysis are generally in a good agreement with the ground-based data in the context of occurrence of the ‘ozone hole’ and the TOC seasonality The TOC bias (∆TOC (DU)) and relative difference (∆TOC(%)) on the daily mean scale are -2 0±9 6(1σ)DU and -0 6±4 3%(1σ) for Merra2 and -0 6±4 3%(1σ) for ERA5 respectively Both the probability distribution of ∆TOC(%)s exhibit each normal random processes and their large variations occurred at the end of March and during the ‘ozone hole’ period The reanalysis data were divided into two periods, 1993-2004 and 2005-2023, based on the changes of satellites to which the reanalysis data were assimilated, but the ∆TOC(%) values (including ERA5) during the ‘ozone hole’ increases with decreasing of the TOC in both periods, and the ∆TOC(%) values for Merra2/ERA5 were respectively 6 9%±4 6%(1σ)/4 6%±2 0%(1σ) and -0 4%~2 3%(1σ)/ 6 4%±3 1%(1σ) Whereas the corresponding averages for the non-ozone hole periods were respectively of only 0 3% ± 1 5% (1σ)/0 6% ± 1 4% (1σ) The ∆TOC (%) of Merra2 and ERA5 show an increasing trend with the solar zenith angle (SZA) during 1993 -2004, with each magnitude of 3% and 2%, while the opposite trend is observed from 2005 to 2023, with magnitude of -2% and 2% respectively for Merra2 and ERA5 Merra2 (ERA5) is systematically lower (higher) than the observed TOC after 2005 (2012), with ∆TOC (%) as low(high) as more than 6% Both the ERA5 and Brewer data show a clear TOC recovery trend during the last 30 years of the ‘ozone hole’ periods whereas neither of them is characterized by a clear trend during the last 31 years of the non-ozone hole periods Correspondingly, the data of Merra2 exhibits clear TOC deletion trends Both the reanalysis TOC data validated by Brewer's observation show their consistent recovery trends of TOC, and the recovering rate of ERA5 is 1 3 DU/10a The study suggests that raw reanalysis TOC data should be used with much caution before evaluating the long-term trends of the ozone layer, and the data from the ground-based observations, albeit the number is much lower than that of reanalysis outputs due to seasonal SZA or weather conditions, is critical for the reanalysis TOC validation and conclusions of TOC trend
　

Observation and analysis of plasma bubbles in Hainan during the magnetic storm in March 2015

, Available online , doi: 10.11728/cjss2025-0004

Abstract(230) PDF 1335KB(12)

Abstract:
The ionospheric plasma bubbles over Hainan during the super geomagnetic storm in March 2015 are studied using airglow images of 630 nm emission from all-sky imager, digisonde and echo intensity data of Viral Hemorrhagic Fever (VHF) radar over Hainan Fuke Station (19.5°N, 109.1°E) from the Chinese Meridian Project, horizontal magnetic component data from the Dalat geomagnetic station (11.9°N, 108.5°E; GL:2.5°) and PHU Thuy geomagnetic station (21.0°N, 105.9°E; GL:11.5°), and interplanetary magnetic field and solar wind velocity data from the ACE satellite. The results indicate that plasma bubbles before and after magnetic storm are observed during post-sunset hours, along with a uplift of the ionospheric virtual height. During the storm, the uplift of the ionospheric virtual height is significantly suppressed, and no plasma bubbles are detected at the Fuke station. Analysis of the variations in the interplanetary electric/magnetic fields and horizontal geomagnetic components suggests that during the geomagnetic storm, the ionospheric Pre-reversal enhancement electric field is likely suppressed successively by the westward shielding electric field and the disturbance dynamo electric field. This suppression reduced the Rayleigh-Taylor instability, thus inhibiting the development of plasma bubbles/ionospheric irregularity structures.

Optimization and Analysis of NRHO Two-pulse Phasing Problem in Cislunar Space

, Available online , doi: 10.11728/cjss2025-0013

Abstract(431) PDF 1850KB(18)

Abstract:
During the construction and operation of the lunar gateway in the artemis program, a large number of cargo and crew rendezvous missions will be conducted in the near-rectilinear halo orbit (NRHO). Addressing the optimization of phase orbits in NRHO, based on the circular restricted three-body problem (CRTBP) model, the transfer time is first traversed using the trust-region methods. Subsequently, the position is locally optimized using a nonlinear optimization algorithm. Finally, the velocity increment is reduced by iteratively solving nonlinear equations, achieving NRHO phasing with low fuel consumption. For the problem of fuel cost, the method analyzes orbital transfer scenarios with different transmission time and phase relationships in NRHO. The results show that the algorithm has high computational efficiency, reducing computation time by 53.2% compared to the genetic algorithm; the longer the transfer time (the more transfer orbit revolutions), the smaller the velocity increment consumed; selecting the outer loop of NRHO for phasing saves fuel when the target spacecraft lags in phase, while the inner loop saves fuel otherwise; the transfer cost is lower when the tracking spacecraft departs from the perilune.

Research on Regional GNSS Elevation Anomaly Fitting Method based on IHHO-LSSVM

, Available online , doi: 10.11728/cjss2024-0180

Abstract(266) PDF 1229KB(0)

Abstract:
In order to solve the problem that it is difficult to obtain high-precision elevation outliers in complex areas, this paper proposes an elevation anomaly fitting method based on IHHO-LSSVM. Firstly, the Harris Hawk Optimization algorithm is improved using nonlinear convergence factors, jump distances, and adaptive weights; Then, the improved HHO algorithm is used to provide more accurate regularization parameters and kernel functions for the Least Squares Support Vector Machine elevation anomaly fitting model; Finally, to verify the adaptability of the elevation anomaly combination model in complex terrain, the root mean square error of the elevation anomaly values was used as the evaluation basis, and experiments were conducted using engineering case data from two different terrains. The results show that in the bridge strip area and karst surface area, compared with the HHO-LSSVM method and LSSVM method, the IHHO-LSSVM method has higher external conformity accuracy, stronger stability, and wider adaptability. The accuracy of the bridge strip area reaches 0.0101m, and the karst surface area reaches 0.0125m, which can provide certain reference value for the establishment of GNSS elevation anomaly fitting models.

, Available online , doi: 10.11728/cjss2024-0175

Abstract(204) PDF 1117KB(15)

Abstract:
The temperature field of the material in the solidification process has an important influence on the final quality of the material. Due to the difference between the space microgravity environment and the ground gravity environment, there are certain differences in the heat transfer characteristics between the ground and space, which leads to the difference in the temperature field distribution in the high temperature material experimental furnace. As a result, the heat transfer characteristics obtained in ground experiments cannot be applied to space experiments. This will have an impact on the success of space materials experiments. Compared with the ground, the heat transfer parameters of the space high temperature material experimental furnace will change during the experiment, but these heat transfer parameters are difficult to measure during the experiment and cannot be accurately obtained. In this paper, a three-dimensional numerical calculation model of heat transfer in the high temperature material experiment furnace of the space station is established and the model is simplified reasonably. The temperature field simulation of the ground experiment and space experiment is carried out respectively, thus the temperature distribution of the sample box is obtained, and the temperature obtained by simulation is compared with that of the space experiment. The variation of heat transfer parameters in the space microgravity environment and the ground normal gravity environment is analyzed, and the heat transfer law similar to the space condition is obtained. This project provides a new way to predict the spatial temperature field distribution of high temperature cabinet material experimental furnace based on the results of ground experiments.

Research on Calibration Techniques for Asymmetric Spatial Heterodyne Interferometers

, Available online , doi: 10.11728/cjss2024-0143

Abstract(323) PDF 1204KB(17)

Abstract:
The detection of wind in the middle and upper atmosphere has important scientific and practical value for the construction of atmospheric models, satellite orbit prediction, communication and navigation support, and space weather disaster prediction. The Doppler shift of airglow radiation obtained by optical interferometer is one of the most important methods for remote sensing of atmosphere wind. Ensuring the accuracy of these measurements necessitates the calibration of the wind measurement performance of optical interferometers. In this paper, we propose the concept of wind measurement sensitivity coefficient through studying the wind measurement principle of asymmetric spatial heterodyne interferometer, providing a solid theoretical foundation for instrument calibration. Two typical calibration systems are designed and implemented to calibrate an asymmetric spatial heterodyne interferometer. By examining both the calibration process and results, we conduct a comprehensive evaluation of the uncertainty and applicability of these two systems. The acousto-optic frequency shift calibration system boasts an uncertainty of less than ±1 m/s, coupled with its compact design and ease of integration, making it an ideal transfer standard for internal calibration within ground wind measurement networks. On the other hand, the reflective wheel calibration system demonstrates wide applicability across various light sources. The findings presented in this paper can serve as a valuable reference for both laboratory and routine field calibration of wind-measuring optical interferometers.

Research on Ground Simulation Method of Heat Transfer Characteristics for Space High-Temperature Material Experimental Furnace Based on Data-Driven Approach

, Available online , doi: 10.11728/cjss2023-0023

Abstract(483) PDF 1291KB(53)

Abstract:
The temperature stability during the crystal growth process has a significant impact on the morphology and structure of the crystal. In order to improve the quality of crystals, it is necessary to ensure the stability of temperature throughout the crystal growth process. Currently, in China, PID controllers are used to control the crystal growth temperature in space high-temperature material science experimental furnaces. Due to the limited and scarce opportunities for space experiments, the tuning of control parameters needs to be completed on the ground. However, due to the difference in heat transfer between the ground and space environments, there are differences in the heat transfer characteristics of the furnace, and its transfer functions are also different. If the control parameters tuned on the ground are directly applied to space conditions, it will result in a worse temperature control effect. To address this, this paper proposes a data-driven depressurization method that approximates and simulates the heat transfer characteristics of the furnace under microgravity environments on the ground, and provides the pressure values for ground adaptation conditions. This overcomes the problem of the traditional depressurization method being difficult to determine the pressure value for ground adaptation conditions due to lack of prior knowledge.

Nighttime Exospheric Temperature Maximum During Quiet Time of Solar Minimum Period Based on Swarm Satellites

, Available online , doi: 10.11728/cjss2024-0032

Abstract(341) PDF 2230KB(8)

Abstract:
The nighttime exospheric temperature maximum is an important part of the characteristics of upper atmospheric temperature variations, which contributes to the understanding of atmospheric temperature and the improvement of the neutral atmosphere model. Previously, due to the scarcity of upper thermosphere temperature observations, studies of the nighttime exospheric temperature maximum were mainly based on single-site and joint observation of ground-based FPI stations as well as simulation studies of the phenomena and mechanisms of various neutral atmosphere models and ionospheric models. The work in this paper carries out the statistics of global and seasonal variations of the nighttime exospheric temperature maximum during solar minimum period by deriving the exospheric temperature obtained from the neutral density of the Swarm satellite accelerometer. The results show that the stronger the solar activity is, the higher the probability and intensity of the occurrence of the nighttime exospheric temperature maximum, and the higher the probability of multiple maximum peaks. When F10.7 is between 80 and 100, the temperature enhancement occurs in all four seasons and in different longitude sectors, but with differences in morphology and intensity. For F10.7 less than 80, the temperature enhancement is stronger and longer in spring and fall, and weaker in summer and winter. In addition, the presence or absence of nocturnal enhancement varies from sector to sector.

, Available online , doi: 10.11728/cjss2024-0019

Abstract(646) PDF 902KB(45)

Abstract:
The new electromagnetic catapult microgravity device employs linear motors to drive the experimental module in vertical motion, simulating a microgravity environment. In comparison to traditional drop tower methods, utilizing a catapult for parabolic motion significantly extends the duration microgravity time. However, the linear motor's drive introduces new challenges in ensuring a high level of microgravity quality. To meet the experimental requirements of microgravity science, this paper conducts a model analysis of the segmented dragging system of the electromagnetic catapult drop tower. It proposes a segmented control scheme and designs a displacement-tracking control algorithm for addressing motor coordination issues affecting microgravity levels and the coordination between inner capsule and outer capsule. This ultimately achieves prevention of disturbance from outer capsule to the inner capsule. The practical system has been constructed and put into operation, employing the motor control method outlined in the paper, enabling microgravity time around 4 seconds. This research provides crucial support for the development of microgravity experimental devices.

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