空间科学学报

Accurate Fruit and Vegetable Detection Method for Space Station Cargo Bay

, Available online , doi: 10.11728/cjss2025-0080

Abstract(30) PDF 1490KB(1)

Abstract:

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(33) PDF 1193KB(2)

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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(46) PDF 1621KB(7)

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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(81) PDF 1065KB(9)

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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(115) PDF 2189KB(15)

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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(80) PDF 686KB(5)

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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.

Standard Dataset for Automated Detection of Small-scale Swirls in the Solar Photosphere

, Available online , doi: 10.11728/cjss2025-0087

Abstract(72) PDF 1276KB(3)

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Small-scale photospheric swirls are widely believed to form as a natural consequence to granular flows, and they may play a key role in transporting energy to the solar upper atmosphere. However, there are significant limitations and biases associated with the manual detection of these small-scale swirls, which may lead to an underestimation of their total number. The Swedish 1-m Solar Telescope (SST) and Solar Optical Telescope (SOT) onboard Hinode spacecraft provide high-resolution and high-quality observations of the solar photosphere, offering abundant data support for the study of small-scale swirls. With the support of a project focused on identifying solar-terrestrial space weather events and modeling physical parameters, a team from the University of Science and Technology of China has developed a new software tool for the automated detection and extraction of key parameters of small-scale swirls in the solar photosphere based on datasets provided by the SST and SOT telescopes. This dataset includes observations from the SOT telescope of a quiet region in the photosphere in 2007, with a pixel scale of 39.2 km and a time interval of approximately 6.4 s, as well as observations from the SST telescope of a quiet region in the photosphere in 2012, with a pixel scale of 43.6 km and a time interval of 8.25 s. This dataset plays an important role in research on the distribution of photospheric swirls in different solar regions and at different phrases of the solar cycle, as well as their formation mechanisms.

Dataset of Geomagnetic Ultra-Low Frequency Waves Based on Meridian Project Observation Data

, Available online , doi: 10.11728/cjss2025-0084

Abstract(71) PDF 1305KB(8)

Abstract:
The Meridian Project, as an important space environment monitoring infrastructure in China, is of great significance in space physics research, especially providing key support for the observation of Ultra-Low-Frequency (ULF) waves. Based on the second-sampled data of the horizontal component (H) and declination component (D) of the geomagnetic field collected by multi-station fluxgate magnetometers of the Meridian Project from 2011 to 2021, this paper constructs a high-quality and long-time-series dataset of geomagnetic ULF waves through data cleaning, noise reduction preprocessing, and combined with time-frequency analysis (Morlet wavelet transform) and statistical methods. The dataset covers 5 stations at high, middle and low latitudes, includes event annotations and original sequences of Pc3-Pc5 regular pulsations, and is stored in JSON format, supporting reading by mainstream scientific research software. This dataset fills the gap in regional ULF wave observations, provides basic data for research such as magnetospheric fluctuations and space weather modeling, helps improve China's space environment monitoring capabilities, and can be used for automatic ULF wave identification and coupling mechanism research.

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(102) 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(113) 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(140) PDF 1816KB(5)

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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(108) PDF 1402KB(5)

Abstract:
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(108) PDF 1872KB(8)

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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(161) PDF 1486KB(7)

Abstract:
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(125) PDF 1040KB(5)

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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(119) 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(186) 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(136) PDF 1721KB(6)

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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(144) PDF 2564KB(13)

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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.

Task-Driven Satellite Cluster Self-Organization Method Based on Linear Groups in Finite Fields

, Available online , doi: 10.11728/cjss2024-0120

Abstract(173) PDF 1957KB(3)

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With the rapid development of space technology and satellite networks, large-scale satellite clusters have become crucial means for executing complex tasks. However, traditional centralized task allocation methods exhibit limitations in real-time responsiveness and robustness as the number of satellites increases and task demands become more complex. To address these challenges, this paper proposes a capability modeling and cognitive state representation method for satellite agents based on finite field linear groups and designs an autonomous task allocation algorithm accordingly. By mapping the capabilities and cognitive states of agents to matrices and vectors over finite fields and leveraging the algebraic properties of finite field linear groups, efficient information exchange and collaborative decision-making among agents are achieved. Additionally, we develop an interactive satellite capability publishing and subscription system based on capability views. Preliminary simulation and on-orbit verification results demonstrate the feasibility of the proposed method, providing theoretical and technical support for task-driven autonomy in satellite cluster systems.

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

, Available online , doi: 10.11728/cjss2025-0029

Abstract(189) 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(143) PDF 1077KB(13)

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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.

, Available online , doi: 10.11728/cjss2024-0095

Abstract(95) PDF 2049KB(5)

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The method of nucleation and solidification of deep subcooled samples in electrostatic levitation is of great importance for materials science research and materials preparation. In this paper, we propose an experimental study of triggered nucleation and measurement of materials under deep subcooling based on the local temperature gradient field of laser pulses. The local temperature gradient field generated by laser pulses increases the free energy difference between solid and liquid phases, thus obtaining the driving force of solid-liquid phase transition and moving the crystal from the equilibrium state of the parent melt to the equilibrium state of the crystal to achieve deep subcooling laser pulse-triggered nucleation. The effects of different heating laser beam spot diameters with the power of 9W, a power density of 2.86×10⁸W/m² and 1.146×10⁷W/m² on the temperature gradient field were investigated by finite element simulation to obtain the results of the local temperature gradient field distribution of the molten sample with different laser beam spot diameters. In the experiments, 2 mm diameter zirconium material samples were used to study the variation of the triggered nucleation time scale for different laser pulse widths and subcooling degrees of the molten material samples at smaller laser beam spot diameters. Based on the classical nucleation theory, the relationship between the time required to move from the equilibrium state of the parent melt to the equilibrium state of the crystal was obtained by statistical analysis of data from 16 groups of 20 spontaneous nucleation per group at different subcooling degrees. The experimental results show that the time required for nucleation solidification of zirconium samples at a low subcooling of 195±3K is 4 times lower than that required for spontaneous nucleation, which verifies that the local temperature gradient field generated by the laser pulse effectively shortens the time required for deep subcooling-triggered nucleation. The local temperature gradient field generated by the laser pulses effectively shortened the nucleation crystallization time.

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

, Available online , doi: 10.11728/cjss2025-0058

Abstract(131) PDF 1242KB(4)

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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(166) PDF 2090KB(11)

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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(241) PDF 1834KB(22)

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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(147) 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(141) 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(163) 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.

Research Progress on Estimating Space Objects Characteristics Using Ground-Based Observation Data

, Available online , doi: 10.11728/cjss2024-0181

Abstract(159) PDF 2785KB(18)

Abstract:
　　
With the increase of space activities and the rapid growth in the number of space objects, the fragmentation and collision of these objects have generated large amounts of space debris, potentially leading to catastrophic consequences. As such, the monitoring and characterization of space objects have become crucial. Information about the geometric, kinematic, and material properties of these objects is critical for target identification, collision avoidance, and active debris removal. The Advanced Maui Optical and Space Surveillance Technologies (AMOS) Conference, a prominent academic platform in the field of space situational awareness, has brought together cutting-edge research on the characterization of space objects. This study systematically reviews and summarizes relevant technical papers presented at the AMOS Conferences from 2016 to 2023. These papers explore the application of ground-based observation data in the characterization of space objects, covering topics such as attitude estimation, shape estimation, attitude evolution, and machine learning-assisted decision-making. Together, they provide a wealth of technical approaches and estimation methods that contribute to the comprehensive analysis of space objects and offer valuable insights for advancing future characterization techniques. In light of the increasing availability of data related to object characterization and the growing maturity of inversion algorithms, this paper proposes a new strategy for establishing a systematic framework for target characteristics estimation in China.

Multi-Parameter Solar Wind Prediction Based on Deep Learning

, Available online , doi: 10.11728/cjss2025-0022

Abstract(204) PDF 2017KB(19)

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(149) 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(217) PDF 2100KB(9)

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(190) 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(170) PDF 1046KB(7)

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(161) 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(161) 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(312) PDF 2520KB(30)

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(225) PDF 1933KB(28)

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(122) 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(189) PDF 1898KB(4)

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(182) 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(218) PDF 1206KB(7)

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(181) PDF 2209KB(13)

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(148) 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.

Doppler Spectrum Analysis of Ground Echoes from Spaceborne Doppler Scatterometer

, Available online , doi: 10.11728/cjss2024-0182

Abstract(234) PDF 1711KB(6)

Abstract:
Sea surface current fields are important oceanic and climatic variables. Due to its capability for global coverage and direct observation of sub-mesoscale sea surface current fields, the Doppler scatterometer has become a frontier in ocean remote sensing technology research. The calibration and quantitative measurement of the Doppler scatterometer are the foundations and prerequisites for current field observations, as well as a critical core issue that needs to be addressed. In this study, a ground-based scattering echo simulation model was developed to simulate and analyze the Doppler spectrum characteristics of potential natural ground extended targets that could be used for external calibration of spaceborne scatterometers. The changes in these characteristics were compared under different platform motion speeds, incident angles, and azimuth angles. The results indicate that platform motion speed is the primary factor affecting Doppler spectrum characteristics, while variations in incident and azimuth angles also have significant impacts. Simulation results for ground extended targets with different height variations show that the greater the height variation of the target, the larger the Doppler spectrum shift, while changes in the central height have minimal impact on the Doppler spectrum characteristics. Therefore, in the selection of calibration targets, relatively flat extended targets should be chosen. Finally, an analysis of the ground echo Doppler frequency shift was conducted and validated using the DEM model. The findings of this study will provide support for further research on Doppler scatterometer calibration.。

Comparative study of geomagnetic models with different spatio-temporal resolutions and measured data from geomagnetic stations

, Available online , doi: 10.11728/cjss2025-0001

Abstract(243) PDF 3135KB(13)

Abstract:
This study focuses on four INTERMAGNET geomagnetic stations located in the Arctic region and South Atlantic Anomaly regions, where rapid magnetic field changes have been observed in recent years. Utilizing two global geomagnetic field models with different spatial and temporal resolutions, the International Geomagnetic Reference Field (IGRF) model and the Swarm model, a multi-field source model that currently has the highest spatiotemporal resolution in the country, are used to quantitatively investigate the impact of model spatial resolution and updating period on the measured values at geomagnetic observatories. The findings indicate that: (1) For regions without distinct lithospheric magnetic anomalies, the results provided by IGRF and Swarm model are relatively close. However, for regions with more prominent lithospheric magnetic anomalies, the Swarm model with higher spatial resolution provides better agreement with the measurements. (2) In one IGRF updating cycle, there is a significant temporal drift between the geomagnetic station measurements and the IGRF model, with typical drifts up to 100 nT or more, but there were also regional variations in the magnitude of the drift, which was related to the heterogeneity of global variations in the geomagnetic field. In contrast, no significant drift was observed between the geomagnetic station observations and the Swarm model. These results suggest that it is necessary to shorten the updating period of the primary magnetic field during the period of rapid geomagnetic field changes. The statistical results from 120 INTERMAGNET stations around the world also show that, in the five-year update cycle of IGRF, the mean and absolute median differences between the residuals of the Swarm model and the observation results are smaller than those of the IGRF model, and the calculation results of the higher spatial and temporal resolution Swarm model are closer to the observations, which describes the geomagnetic field more accurately. This work can provide the basis and reference for the application of global geomagnetic model.

Research on the segmentation algorithm of X-ray microstructure image of Na₆Mo₁₁O₃₆ material

, Available online , doi: 10.11728/cjss2024-0185

Abstract(176) PDF 1547KB(10)

Abstract:
Conducting materials science experiments in a microgravity environment mitigates the influence of gravity, enabling the study of intrinsic material growth mechanisms and the fabrication of materials with enhanced properties. The High-Temperature Materials Science Experimental Cabinet aboard the Chinese Space Station is equipped with an X-ray transmission imaging module, facilitating real-time imaging and observation of material solidification processes under microgravity. However, due to the constraints of the space station's experimental conditions, the X-ray images acquired by this module often exhibit blurriness, making direct observation of microstructures challenging. To address this issue, This paper proposes the GC-UNet++ image segmentation algorithm, specifically tailored for analyzing the microstructures formed during the solidification of Na₆Mo₁₁O₃₆ material. The algorithm's effectiveness is rigorously evaluated in terms of both image segmentation performance and its relevance to materials science applications. The experimental results demonstrate that in the image segmentation task, GC-UNet++ outperforms established algorithms such as UNet, UNet++, DC-UNet, UNet3+ and Pretrained-Microscopy-Models, achieving notable improvements across various image segmentation metrics. Furthermore, the microstructures formed during the growth of the Na₆Mo₁₁O₃₆ material can be segmented more accurately. This provides new ideas and methods for the study of the microstructure segmentation of materials, and has important application value.

, Available online , doi: 10.11728/cjss2025-0009

Abstract(249) PDF 1988KB(23)

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(202) PDF 1335KB(11)

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.

A multiplicative model with frequency-domain features superimposed on time-domain mutations for predicting ionospheric TEC methods

, Available online , doi: 10.11728/cjss2024-0123

Abstract(212) PDF 907KB(8)

Abstract:
Total Electronic Content (TEC) is an important characteristic parameter of the ionosphere, which has a great influence on the navigation error correction and other applications, but the current ionospheric TEC prediction accuracy cannot fully meet the demand, and there are deficiencies in the accuracy and lead time. The paper focuses on the needs of regional ionospheric TEC forecasting, comprehensively considers the characteristics of ionospheric TEC in both frequency and time domains, analyzes the ionospheric TEC changes in multiple cycle lengths in the frequency domain according to the characteristics of trend, periodicity, and suddenness of the changes in the ionospheric TEC affected by solar activities, considers the suddenness of the geomagnetic storms and other factors on the ionospheric TEC in the time domain, and considers the Dst index and latitude/longitude as the input parameters for forecasting. forecast input parameters, and train the specificity of the magnetosphere-ionosphere coupling in each region. The experimental results show that in the geomagnetically quiet period, the RMSE of the 7-day forecast is better than 1.262 TECU, and the RMSE of the 1-day forecast is better than 1.094 TECU; in the geomagnetically active period, the RMSE of the 7-day forecast is better than 4.186 TECU, and the RMSE of the 1-day forecast is better than 4.115 TECU. model, and the method performs well in terms of forecasting accuracy and timing.

, Available online , doi: 10.11728/cjss2024-0162

Abstract(196) PDF 1109KB(10)

Abstract:
Terahertz solid-state Schottky harmonic mixing technology is an important means of space astronomy, planetary exploration, and atmospheric detection. Obviously, the research on terahertz monolithic integrated harmonic mixers is of great significance, as it overcomes a series of problems such as assembly difficulty, thermal imbalance, and poor reliability that exist in traditional hybrid integration methods (discrete Schottky diodes are glued to quartz matching circuits). Based on the domestic gallium arsenide process line, the development and verification of a 550 GHz monolithic integrated harmonic mixer are independently completed. For diode design, accurate nonlinear and 3D models of Schottky diodes are established. For circuit matching, typical structures are adopted, such as reduced height waveguides, stepped impedance lines (to isolate RF and LO signals), rectangular probes. Combined with field-circuit analysis methods the simplest matching circuit design is realized. The mixer circuit includes diodes integrates on a 3 μm GaAs thin film, and is fixed with the cavity through the beam leads on both sides. The test results show that the single sideband conversion loss of the mixer is better than 13.4 dB at 548~572 GHz. Based on this result, a feedback simulation study of the design is achieved.

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

, Available online , doi: 10.11728/cjss2025-0013

Abstract(390) PDF 1850KB(17)

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(166) 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.

Imaging method of synthetic aperture radio telescope based on minimum-maximum concave penalty

, Available online , doi: 10.11728/cjss2024-0186

Abstract(203) PDF 2959KB(1)

Abstract:
In the synthetic aperture radio telescope, the reconstruction of the radiation signal from the measured visibility function is an ill-posed inverse problem. Although compressed sensing technology has been successfully applied in synthetic aperture radio telescope imaging, the traditional compressed sensing algorithm uses L₁ norm to approximately replace L₀ norm, which brings some bias. To address this problem, a new imaging method of synthetic aperture radio telescope based on min-max concave penalty is proposed. The method uses the min-max concave penalty to approximate the L₀ norm and the fast iterative shrinkage-thresholding algorithm to solve the minimization model. In the iterative process, the regularization parameter is selected adaptively by using maximum likelihood estimation, and the convergence speed is improved by using restart and adaptive strategies. The experimental results show that the proposed method is superior to the current typical compressed sensing algorithms in terms of reconstruction accuracy and noise suppression, which proves its effectiveness.

Research Progress on Long-lived Technologies of Venus Lander

, Available online , doi: 10.11728/cjss2024-0178

Abstract(306) PDF 1575KB(13)

Abstract:
Venus is an important part of terrestrial planets, and the exploration and research of Venus has high scientific value. The extreme environment of high temperatures, high pressures, and corrosiveness on the surface of Venus fundamentally limits human exploration of it in situ. Based on the future needs of long-lived exploration of the surface of Venus, this paper analyzes the challenges of long-lived of the lander according to the characteristics of the Venus environment, and sorts out the research progress of the long-lived technology of the Venus lander from three aspects: lightweight high-pressure resistant structure design, high-temperature electronic equipment, power system and thermal control technology, which provides a reference for the possible future exploration of Venus landing in China..

, Available online , doi: 10.11728/cjss2024-0175

Abstract(176) 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.

Hydrated minerals detection on Mars with hyperspectral remote sensing: principles, current status, and prospects

, Available online , doi: 10.11728/cjss2024-0173

Abstract(778) PDF 1053KB(77)

Abstract:
Mars is the most Earth-like terrestrial planet in the solar system and a primary focus of deep space exploration due to its potential habitability. Hydrated minerals, formed through water-rock interactions, provide essential insights into Mars’ early aqueous environment, geological evolution, and habitability. Hyperspectral remote sensing, with its ultra-high spectral resolution, has proven invaluable for identifying and quantifying these minerals. However, the sparse distribution and low abundance of hydrated minerals, along with challenges from spectral mixing and noise, have constrained current detection methods. These approaches, primarily relying on spectral parameters and visual interpretation, struggle to meet the demands of large-scale hyperspectral data processing. Recent advances in machine learning for terrestrial hyperspectral remote sensing offer innovative approaches to Martian mineral mapping, yet their application remains at an early stage. This review summarizes progress in the hyperspectral detection of Martian hydrated minerals, covering qualitative identification and quantitative abundance retrieval. It assesses the advantages, limitations, and applicability of existing methods and proposes future directions to advance this field.

Research on Calibration Techniques for Asymmetric Spatial Heterodyne Interferometers

, Available online , doi: 10.11728/cjss2024-0143

Abstract(294) PDF 1204KB(16)

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.

, Available online , doi: 10.11728/cjss2024-0136

Abstract(236) PDF 1246KB(13)

Abstract:
　　
　　In this study, we focus on the morphological features of the interhemispheric asymmetry and latitude offset phenomenon of the equatorial ionization anomaly (EIA) at equatorial and low-latitude magnetic regions in winter by statistics of the parameters -TEC and hmF2 around 120°E longitude during 1998-2020. The results showed that: (1) The hemispherical asymmetry features of EIA structure that vary with solar activity are significantly different during the summer and winter solstice. The asymmetry exhibits a significant correlation with the solar activity during winter solstice. However, there is a weak negative correlation during the summer solstice. (2) The latitude position of EIA structure moves southward in winter months and the latitude deviation of southern anomaly crest is more significant, especially during the low solar activity. The hemispherical asymmetry is mainly affected by the trans-equatorial neutral wind field during the winter solstice. On the other hand, photo-ionization can produce more electrons under the subsolar point, and the effect may plays an important role in Southward offset phenomenon of EIA structure in winter around 120°E longitude.

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(461) 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(305) 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(603) PDF 902KB(43)

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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