空间科学学报

, Available online , doi: 10.11728/cjss2024-0095

Abstract(13) PDF 2049KB(1)

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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

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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

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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-yg02

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, Available online , doi: 10.11728/cjss2025-0018

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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(28) PDF 1533KB(8)

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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(36) PDF 1978KB(1)

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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

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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 on the Electromagnetic Locking Device for Aerial Towed System Probe Docking

, Available online , doi: 10.11728/cjss2024-0196

Abstract(32) PDF 1018KB(3)

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The research object is the aerial towed system probe docking. An electromagnetic locking device is designed. The electromagnetic locking principle of rapid locking and emergency release is given. By establishing the finite element model considering the docking process, the response data of the electromagnetic docking mechanism is obtained considering the electromagnetic force as a variable. It provided a theoretical basis for the development of electromagnetic locking device for aerial towed system probe docking. This docking electromagnetic locking device provides a new idea for the design of the aerial towed system probe docking.

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

, Available online , doi: 10.11728/cjss2024-0181

Abstract(50) PDF 2785KB(1)

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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(56) PDF 2017KB(6)

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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

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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(44) PDF 2100KB(1)

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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.

Microgravity-induced disruption of mitochondria-spindle-chromosome coordination causes meiosis defects in mouse oocyte

, Available online , doi: 10.11728/cjss2025-yg03

Abstract(78) PDF 1691KB(5)

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This study employed a ground-based microgravity analog system to assess mouse oocyte meiotic progression and developmental competence, providing mechanistic insights into space environment-induced defects during oocyte maturation. Germinal vesicle (GV)-stage mouse oocytes were encapsulated in polydimethylsiloxane (PDMS) chip chamber and subjected to simulated microgravity (SMG) culture using a random positioning machine (RPM). Meiotic dynamics were systematically analyzed at five key stages: GV (0 h), GV breakdown (GVBD, 2 h), pro-metaphase I (Pro-MⅠ, 5 h), metaphase I (MⅠ, 8 h), and metaphase II (MⅡ, 16 h). Mitochondrial distribution, spindle morphology, and chromosome alignment were quantified through confocal laser microscopy coupled with fluorescent probes. The results showed that SMG exposure reduced oocyte maturation rates by 32.75% compared to normal gravity (NG) controls (p<0.01). Mitochondrial dynamics exhibited stage-specific perturbations: perinuclear clustering at MI (70.00% vs 41.18% in NG) and disorganized aggregation patterns in 71.88% of MII oocytes. Spindle assembly and chromosome alignment were also disrupted: multipolar spindles during MⅠ caused disordered chromosome segregation. At MⅡ, SMG oocytes displayed exacerbated spindle defects (57.58% abnormality rate vs 22.32% in NG, p<0.05) and widened equatorial plates (15.63 μm vs 7.55 μm, p<0.0001). These findings suggest that SMG exposure compromises meiosis and oocyte quality through tripartite disruption of mitochondrial-spindle-chromosomal coordination. These results provide important insights into how mechanical perturbations regulate subcellular structure interaction networks to affect oocyte quality.

, Available online , doi: 10.11728/cjss2024-0130

Abstract(46) PDF 2195KB(1)

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TLE data provided by the ELSETS space debris catalog database is one of the main sources for publicly obtaining orbital information. Due to the fluctuation in the accuracy of TLE data, it is difficult to further improve the orbital prediction accuracy of TLE data orbit determination results obtained by traditional static orbit determination methods. Therefore, based on the simplex optimal search algorithm, this paper introduces a time variable and solves it together with other orbital elements to achieve dynamic orbit determination. This paper conducts experiments using eight satellite with their TLE data and GPS data. Compared with the orbit determination results of the simplex optimal search algorithm without considering the time variable, the orbital prediction accuracy is improved by 18.85 - 70.3%, and the errors are significantly reduced in S and W directions. Especially for some satellites, the true position error of orbit prediction within one day has been reduced nearly to 0km.

Research Progress on Atmospheric Dynamics in the Aerospace Transition Zone

, Available online , doi: 10.11728/cjss2025-yg01

Abstract(78) PDF 1066KB(15)

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The aerospace transition zone refers to the region between traditional aviation and space activities, specifically the atmospheric layer from 20 kilometers to 150 kilometers above the Earth's surface. With the accelerated development of aerospace integrated space environment services, the modeling and forecasting of atmospheric dynamics in the aerospace transition zone have received increasing attention from various disciplines while significant progress has been made on the microphysical processes and mechanisms of the aerospace transition zone atmospheric disturbances. This study reviews the recent research status of the aerospace transition zone atmospheric dynamics, and briefly analyzes the research progress on the impact of solar radiation and polar particle precipitation on the aerospace transition zone atmospheric environment in the coupling chain process of the Sun/solar wind–magnetosphere–the aerospace transition zone. Then, we focus on summarizing the research progress of the coupling between Earth activities-lower atmosphere and the aerospace transition zone by four aspects of gravity waves, planetary waves, tidal waves, and typical lower atmospheric activities. Finally, it looks forward to the future development prospects of the aerospace transition zone and several key issues that need to be solved, providing a certain reference for scholars in atmospheric science and space physics.

Coronal Explorer for our Sun and nearby Stars

, Available online , doi: 10.11728/cjss2025-0060

Abstract(86) PDF 3482KB(12)

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We propose to launch the first extreme-ultraviolet (EUV) space science mission in China to explore the sources of space weather both within and beyond the solar system, specifically the solar and stellar coronae. The primary scientific objects of this mission, Coronal Explorer for our Sun and nearby Stars (CESS), are as follows: (1) Characterize the physical properties of the source regions of solar coronal outflows and eruptions through full-disk EUV spectroscopy of the Sun; (2) Detect stellar coronal eruptions through long-term EUV photometric and spectroscopic monitoring of the coronae of selected nearby late-type stars; (3) Explore the role of space weather in the formation of a habitable world through point-source EUV observations of the Sun and other stars. To fulfill these scientific goals, the spacecraft will be equipped with four key science payloads: an EUV solar-disk spectrometer (comprising a Sun-as-a-star spectrometer and a multi-slit spectrometer with a full-disk field of view), an EUV spectroscopic coronagraph, a stellar EUV spectrometer and a stellar EUV photometer. The CESS mission will contribute to the precise prediction of space weather in the solar system, uncover the origin of exoplanetary space weather, and offer crucial clues for the search for extraterrestrial life.

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

, Available online , doi: 10.11728/cjss2025-0008

Abstract(67) PDF 1159KB(2)

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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(67) PDF 1046KB(5)

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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(54) PDF 1545KB(6)

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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(53) PDF 1529KB(1)

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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(79) PDF 2520KB(12)

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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(70) PDF 1933KB(6)

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(42) 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.

Calibration of Thermospheric Atmospheric Density Empirical Model Based on SegRNN

, Available online , doi: 10.11728/cjss2024-0179

Abstract(70) PDF 1608KB(5)

Abstract:
Atmospheric drag is the largest non-gravitational perturbation experienced by low-orbit satellites, and the main source of error in calculating atmospheric drag stems from inaccuracies in the empirical models of thermospheric density. Currently, these empirical models generally exhibit errors exceeding 30%. To enhance the prediction accuracy of these models, a calibration method for thermospheric density empirical models based on Segment Recurrent Neural Network (SegRNN) is proposed. This method employs the segmentation and parallelism strategies of SegRNN for model training and inference, mitigating the issues of error accumulation and gradient instability that arise from excessive iterations in traditional RNNs. By analyzing the relationship between atmospheric density and external environmental parameters such as Ap, F_10.7, and F_10.7a, an improved neural network architecture named "SegRNN with Residual Block" is proposed. This architecture introduces external environmental parameters as dynamic covariates and employs Residual Block to encode these covariates, thereby extracting density-related information for the prediction period and further enhancing the prediction accuracy of SegRNN. Finally, the density data derived from the onboard accelerometer of the GRACE (Gravity Recovery and Climate Experiment) satellite is used to calibrate the NRLMSISE 2.0 model. The results indicate that the original error of the NRLMSIS 2.0 model is 31.3%. After calibration with SegRNN, the error was reduced to 8.0%. By introducing dynamic covariates, the model error was further reduced to 7.2%. Ultimately, the error of the final calibrated model decreased by 24.1%, demonstrating significant calibration effects.

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

, Available online , doi: 10.11728/cjss2025-0023

Abstract(57) PDF 1898KB(0)

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(58) PDF 911KB(4)

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(81) PDF 1206KB(3)

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(67) PDF 2209KB(9)

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(49) PDF 1254KB(2)

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.

Compared Analysis of Retinal Protein Expression induced by Neutron Radiation and Microgravity

, Available online , doi: 10.11728/cjss2024-0133

Abstract(60) PDF 1157KB(3)

Abstract:
Objective: This study employs bioinformatics methods to analyze and compare the effects of neutron radiation and microgravity environments on retinal protein expression in mice, providing a biological basis for understanding the mechanisms of retinal damage induced by space environments. Furthermore, it offers insights for risk assessment and protective measures related to space environments.
Methods: In this study, we obtained differential expression data of retinal proteins in mice exposed to neutron radiation and microgravity environments. Various bioinformatics methods, including GO and KEGG enrichment analyses, PPI network construction and module analysis, and Hub protein screening and analysis, were employed to compare the effects of neutron radiation and microgravity on retinal protein differential expression.
Results: The results showed that there were differences in the most significantly enriched functions. Neutron radiation inducement primarily enriched in functions such as “response to xenobiotic stimulus”, “actin filament”, and “identical protein binding”. Microgravity inducement enriched in functions such as “lens development in camera-type eye”, “mitochondrion”, and “structural constituent of eye lens”. The KEGG analysis showed that the changes in the “Motor proteins” pathway were consistent under both neutron radiation and microgravity inducement. In addition, neutron radiation inducement also enriched in the “Focal adhesion” and “Regulation of actin cytoskeleton” pathways, while microgravity inducement also enriched in the “Cardiac muscle contraction” pathway. The Hub proteins and biological process (BP) of the most significant modules were different. The most significant BP under neutron radiation inducement was “muscle contraction”, while under microgravity inducement, “camera-type eye development” was the most significant. Under different inducement, the expression trends of proteins PMEL, PTN, TPM1, and RAB27A were consistent. However, PDPN showed an opposite change.
Conclusion: The study results suggest that retinal proteins respond differently to neutron radiation and microgravity stimuli. These findings have the potential to elucidate the mechanisms of retinal damage caused by space radiation or microgravity and provide a reference for developing targeted protective measures.

The use of NeQuick G model and COSMIC-2 occultation data in ionospheric tomography algorithm

, Available online , doi: 10.11728/cjss2024-0077

Abstract(65) PDF 1595KB(4)

Abstract:
As an effective means of ionospheric monitoring, The NeQuick G model and Global Navigation Satellite System, GNSS Constellation Observing System for Meteorology Ionosphere and Climate 2, COSMIC-2 occultation provides the electron density and total electron content of the ionosphere at any time and space, respectively, TEC model data and measured ionospheric profile data. The ionospheric analysis algorithm based on GNSS data can reconstruct the spatiotemporal distribution of the ionosphere at any time, especially during periods of ionospheric disturbances. However, the ionospheric tomography algorithm is also limited by uneven data coverage and low vertical inversion accuracy. This article improves the three-dimensional ionospheric tomography algorithm by integrating the NeQuick G model profile and COSMIC-2 profile observation data. COSMIC-2 data is also used as one of the inputs to the tomography algorithm to reconstruct the ionospheric electron density distribution during the ionospheric disturbance phase in China and surrounding areas on November 3 and 4, 2021. At the same time, the observation data of the ionosonde was used as real data to evaluate the peak electron density (NmF2) and peak height (hmF2) of the F2 layer in the tomography inversion. The experimental results show that the improved NmF2 chromatography results have a Root Mean Squared Error, The highest improvement percentage for RMSE is 48.96%; The RMSE improvement percentage of the improved hmF2 chromatography results is the highest at 72.43%.

Doppler Spectrum Analysis of Ground Echoes from Spaceborne Doppler Scatterometer

, Available online , doi: 10.11728/cjss2024-0182

Abstract(77) PDF 1711KB(2)

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(104) PDF 3135KB(9)

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.

Global Ionospheric Response to the Geomagnetic Storms from March to April 2023

, Available online , doi: 10.11728/cjss2024-0198

Abstract(91) PDF 1634KB(9)

Abstract:
Abstract This article uses global ionospheric data provided by IGS and employs the sliding quartile range method to study the ionospheric disturbances during two times geomagnetic storms that occurred in March and April 2023. The results are as follows. Coronal mass ejections are the primary cause of geomagnetic disturbances. When combined with factors such as dark stripe bursts, they enhance the intensity of geomagnetic storms and cause significant differences in the occurrence and distribution characteristics of ionospheric TEC disturbances. The ionospheric disturbance during the geomagnetic period in March shows an asymmetric distribution in an east-west direction, while the entire process of ionospheric disturbance during the geomagnetic period in April exhibits a transition from positive phase disturbance to negative phase disturbance. In addition, the ionospheric TEC in the northern hemisphere of the East Asia Australia (120 ° E) line is significantly higher than that in the southern hemisphere. The amplitude changes of ionospheric disturbances are most significant during the recovery phase of geomagnetic storms, showing a distribution pattern of low latitude positive disturbances and mid high latitude negative disturbances.

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

, Available online , doi: 10.11728/cjss2024-0185

Abstract(64) PDF 1547KB(2)

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(101) PDF 1988KB(10)

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(86) PDF 1335KB(6)

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.

Error prediction method of geomagnetic model based on extreme learning machine

, Available online , doi: 10.11728/cjss2024-0109

Abstract(63) PDF 1940KB(6)

Abstract:
Large inherent error of geomagnetic model and long updating time of coefficient are the main reasons that restrict the improvement of geomagnetic navigation accuracy. In order to solve this problem, an error prediction model based on regularized extreme learning machine is proposed in this paper. By establishing the mapping relationship between geomagnetic parameters and time information and geomagnetic field intensity vector elements, combined with real satellite magnetic field measurement data, the error estimation and prediction of geomagnetic field model are realized. Then, a geomagnetic navigation method based on the fusion of model prediction method and extended Kalman filter is proposed. The navigation results are simulated by using the geomagnetic measured data of the orbiting satellite. The results show that: Compared with several conventional neural network prediction methods, the position accuracy of geomagnetic navigation can reach 1.96km, indicating that the proposed error prediction model can effectively improve the performance and accuracy of geomagnetic navigation.

Short arc initial orbit determination of space debris based on commercial space monitoring data

, Available online , doi: 10.11728/cjss2024-0129

Abstract(105) PDF 884KB(7)

Abstract:
As domestic space debris monitoring equipment continues to increase, effectively utilizing the vast amount of observational data to enhance the value of commercial space has become a crucial topic for in-depth research. This paper employs data from China's commercial space company's "Yuanwang-1" space-based observation system and the "Zhulong" ground-based monitoring network to determine initial orbits for GEO (geostationary orbit) and LEO (low Earth orbit) targets. TLEs (Two-Line Elements) are used as known values to estimate initial orbit errors. The results are as follows: for GEO targets, the observation arc length is approximately 49.8 seconds, with initial orbit semi-major axis and inclination errors of 84.4 km and 0.4 degrees, respectively; for LEO targets, the observation arc length is about 84.5 seconds, with initial orbit semi-major axis and inclination errors of 12 km and 0.08 degrees, respectively. The results demonstrate the feasibility of the initial orbit determination algorithm used and highlight the significant potential of space-based and ground-based optical-electronic monitoring equipment in the commercial space sector.

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(85) PDF 907KB(5)

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(88) PDF 1109KB(8)

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(195) PDF 1850KB(9)

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.

A Robust, High-Speed Automated Detection Model for Lightning Whistler

, Available online , doi: 10.11728/cjss2024-0132

Abstract(128) PDF 3382KB(15)

Abstract:
The Zhangheng Satellite has accumulated a vast amount of observational data over its six years in orbit. Detecting all lightning whistler wave (LW) events from this dataset is crucial for comprehensively analyzing the variation patterns of the space physical environment. However, using the current mainstream LW detection technology, which is based on time-frequency spectrograms, it would take approximately 40 years to complete this task. To address the slow inference speed and meet practical engineering demands, this study proposes, for the first time, a high-speed detection model for lightning whistler waves from the perspective of audio event detection—WhisNet. This model reduces the time cost from 40 years to just 54 days. First, waveform data is segmented using a 4-second sliding window; then, Mel-spectrogram audio features are extracted. Next, a lightweight Convolutional Recurrent Neural Network (CRNN) is constructed to further extract the audio event features of LW. Finally, two fully connected networks are created at the output layer to predict the start time and duration of each LW event. To evaluate the model’s performance and computational speed, experiments were conducted on data from the SCM (Search Coil Magnetometer) between April 1 and April 10, 2020. The results show that the performance of the WhisNet model is comparable to that of time-frequency image-based methods, but with a 99% reduction in computational and parameter costs and a 98% increase in computational speed. The model was further applied to SCM data from May 2020, and the detection results were statistically analyzed and visually compared to the average lightning density trend from the WWLLN Global Lightning Climatology and timeseries (WCLG) for May 2020. The high consistency between the two further confirms the applicability and accuracy of the WhisNet model in processing large-scale satellite data. This method offers significant reference value for thoroughly exploring other large-scale geospace events.

Long-term Ionospheric TEC Prediction Model Based on LSTM-SpatioTemporal Transformer

, Available online , doi: 10.11728/cjss2024-0117

Abstract(160) PDF 4561KB(27)

Abstract:
Total electron content (TEC) in the ionosphere is a crucial parameter affecting radio wave propagation and space activities. However, traditional statistical models exhibit significant limitations in handling the high noise, non-stationarity, and complex dynamic characteristics of TEC data. To address this issue, this study proposes a hybrid prediction model combining a SpatioTemporal Transformer (STT) and a long short-term memory (LSTM) network, with the incorporation of attention-weighted auxiliary predictors. In an experimental setting for ionospheric TEC prediction over China and its surrounding regions, data from 2000 to 2022 were used for training, while data from the solar maximum year 2023 served as the test set. The study focused on evaluating the impact of different parameter combinations on TEC prediction performance under varying ionospheric conditions. Ablation experiments demonstrate that the proposed hybrid model outperforms single models. The hybrid model with attention-weighted auxiliary predictors achieved an average relative accuracy (P) of 87.63% on the 2023 test set, compared to 87.45% for the single model. The highest average relative accuracy during geomagnetically quiet and storm periods reached 94.34% and 93.17%, respectively. Furthermore, during the longest geomagnetically quiet period (DOY 221–244) and storm period (DOY 166–181) in the test set, the average relative accuracy (P) reached 90.98% and 90.16%, respectively. These results indicate that the model maintains high TEC prediction accuracy under different ionospheric conditions.

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

, Available online , doi: 10.11728/cjss2024-0180

Abstract(76) 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(96) 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.

, Available online , doi: 10.11728/cjss2024-0094

Abstract(103) PDF 2908KB(2)

Abstract:
The Wallops Arc Second Pointer (WASP) is a high-altitude scientific balloon gondola control system developed by the National Aeronautics and Space Administration (NASA), designed for high-precision astronomical observation missions. This system integrates sophisticated mechanical and electronic components, complemented by super-pressure balloon technology, to conduct long-duration flights in the near-space environment while maintaining sub-arcsecond pointing accuracy. The WASP system's flexibility and standardized design enable it to be adapted to a variety of scientific payloads, catering to diverse mission requirements. In the realm of space science, the application of the WASP system has broadened the research horizons of high-altitude scientific balloons and has provided innovative solutions for the establishment of near-space observatories, furthering the exploration of the near-space domain. The successful test flights and applications of the WASP system have established a solid foundation for its utilization in the fields of planetary science, astrophysics, and Earth observation.

Method of design and modeling for lunar exploration engineering based on UAF

, Available online , doi: 10.11728/cjss2024-0127

Abstract(109) PDF 4962KB(10)

Abstract:
Aiming at the difficulties in system of system (SOS) design and interface verification in lunar exploration engineering, in order to effectively solve the pre-validation problems of requirements, functions and interfaces, under the conditions of adaptive tailoring and combination for Unified Architecture Framework (UAF), the method of design and modeling for lunar exploration engineering based on UAF is proposed. The key links in each phases of lunar exploration are analyzed, the view models based on strategic, operational and resources viewpoint are established, the models are optimized through requirements traceability and logical simulation iterative validation, this method improves the rationality and effectiveness of design and modeling, it provides a feasible reference for the SOS design of lunar exploration engineering.

, Available online , doi: 10.11728/cjss2024-0105

Abstract(121) PDF 2296KB(8)

Abstract:
The ozone valley over the Tibetan Plateau has a significant impact on global climate. To explore the specific temporal and spatial characteristics of the ozone valley, this study primarily utilizes daily total ozone columns, monthly average tropospheric ozone columns, and ozone profiles derived from OMI and MLS over the Tibetan Plateau from 2010 to 2023. The study analyzes the spatial and temporal distribution characteristics of the ozone low-value center over the Tibetan Plateau and briefly discusses the possible causes of this phenomenon. The results indicate that: (1) Compared to other regions at the same latitude globally, the Tibetan Plateau exhibits a distinct low-ozone phenomenon during the summer; (2) Vertically, the low ozone values over the Tibetan Plateau are mainly concentrated within the 15-20 km range, with the lowest value corresponding to an altitude of 16.8 km, roughly at the tropopause; (3) There are significant regional differences in the low-ozone phenomenon within the Tibetan Plateau, with opposite patterns observed between the southern and northern parts during the winter.

Analysis the key elements of Martian habitable environment and its implication for Tianwen-3 site selection

, Available online , doi: 10.11728/cjss2024-0131

Abstract(218) PDF 1767KB(29)

Abstract:
The study of Martian habitable environment is a important aspect of Mars exploraion and plantary science. By summarizing Martian exploration missions and the research achievements, this paper analyzes four key points of Martian habitable environment, including key elements for life (carbon, nitrogen, sulfur and phosphorus), liquid water, climate conditions, and energy sources. Based on these factors, engineering safety, and scientific value, proposing that Utopia Planitia can be the preferred landing region for the Tianwen-3 mission, and further exploring the geological history and habitable environment characteristics of the Utopia Planitia. The results show that Utopia Planitia is an important candidate landing area with both scientific value and safety due to its geologic diversity, liquid water environment, and abundance of life-indicating minerals. This paper provides a reference for the Tianwen-3 mission , which will help the research of life exploration on Mars.

Research Progress on Long-lived Technologies of Venus Lander

, Available online , doi: 10.11728/cjss2024-0178

Abstract(143) PDF 1575KB(9)

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(105) PDF 1117KB(7)

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.

Multi-objective Optimization of Fixed Honeycomb Panel Space Radiator Based on NSGA-II Algorithm

, Available online , doi: 10.11728/cjss2024-0177

Abstract(93) PDF 3878KB(1)

Abstract:
Space radiator is an important part of aerospace thermal control system. In order to meet the heat dissipation and weight reduction requirements of a low-orbit satellite, an optimization strategy of fixed honeycomb plate space radiator has been proposed with the help of inverse design concept, and the root cause of space radiator performance improvement has been expounded from the perspective of macro and micro heat transfer. Taking the layout parameters of heat pipes and fluid loop as the design variables, Kriging was used to construct the surrogate model, and the scheme α and β were obtained by iterative optimization based on NSGA-II algorithm. The simulation results show that the optimization schemes improve the surface temperature uniformity by 3.09K and 4.98K respectively, and improve the heat dissipation capacity by 18.7% and 28.8% on the basis of reducing the mass by about 1/4. The on-orbit temperature level of satellite were compared and analyzed. The verification results show that the optimal design of the radiator makes the spacecraft thermal control system have greater temperature control margin and significant weight reduction advantages, which is more conducive to the development and expansion of spacecraft on-orbit tasks.

Chorus induced rapid evolution of relativistic electron pitch angle distributions in the Earth's outer radiation belt

, Available online , doi: 10.11728/cjss2024-0187

Abstract(84) PDF 1373KB(4)

Abstract:
This paper reports an event of rapid evolution of relativistic electron differential fluxes in the outer radiation belt. Using Van Allen Probe-B data, we examined electron fluxes at L≈5.8, MLT≈2, and Mlat≈1.7 during the period rm 15: 19–15: 49 UT on September 7, 2016. The data show that relativistic electron pitch angle distributions transformed from butterfly-shaped to nearly flat-topped patterns within 30 minutes. Due to the slow orbital speed and minimal position changes of the satellite during this period, this observation can be regarded as an observation at a fixed spatial position. Numerical simulations indicate that the interaction with whistler-mode chorus waves is the primary mechanism for the pitch angle distribution evolution in this event.

Research on Heat Dissipation of Split Diamond/Copper Microchannels

, Available online , doi: 10.11728/cjss2024-0184

Abstract(118) PDF 1083KB(5)

Abstract:
In view of the poor machinability of diamond/copper composites, a split diamond/copper composite microchannel heat dissipation system is designed in this paper and compared with a pure copper microchannel system. The heat transfer characteristics of the two microchannel systems at different flow rates (0.3m/s, 0.5m/s, 0.7m/s) and rib heights (1mm, 1.5mm, 2mm) were investigated using HFE-7100 as the heat transfer medium. When the flow rate is 0.7 m/s, the chip surface temperatures of diamond/copper microchannels at the critical power are lower than those of pure copper microchannels by 12°C, 19°C, and 19.6°C, respectively, with the increase of rib height. The heat transfer coefficients were maximally enhanced by 27.8%, 30.1%, and 28.1% at the three rib heights, respectively, showing the heat dissipation advantages of the diamond/copper composite microchannels. The inlet and outlet pressure differences of the two microchannel systems are almost the same in the single-phase convection section, and the difference gradually arises when entering the nuclear state boiling, and the differential pressures of the diamond/copper microchannel systems are all slightly higher than those of the pure copper microchannel system at the critical power, with a maximum increase of 11.8%.

Scheduling methods for astronomical satellite Target of Opportunity tasks with high-frequency dynamic arrivals

, Available online , doi: 10.11728/cjss2024-0125

Abstract(161) PDF 1274KB(8)

Abstract:
In the context of the growing demand for observing a vast number of variable celestial objects detected by sky survey equipment every day, the long sequence task planning problem consisting of high-frequency dynamic Target of Opportunity (ToO) events and follow-up observations has the characteristics of observation event randomness, high timeliness of data acquisition, multiple selectable options, and complex constraints, often considered an NP-hard problem. Consequently, obtaining labeled data for supervised learning is challenging. When applying unsupervised learning through deep reinforcement learning (DRL) methods to solve the long-sequence task planning problem, satellites as agents find it difficult to quickly converge to a global optimal strategy. To address this, this paper draws on the concept of local attention (LA) to improve the pointer network (PN), proposing the Local Attention Pointer Network (LA-PN) algorithm. This algorithm introduces a time window to focus the model on the crucial sequence parts for the current decision, reducing ineffective exploration. Simulation results demonstrate the algorithm's profitability, real-time performance, and generalization ability.

A quasi-real-time on-chip ionospheric TECKalman filtering algorithm

, Available online , doi: 10.11728/cjss2024-0108

Abstract(161) PDF 809KB(3)

Abstract:
An on-chip quasi-real-time algorithm is proposed for monitoring the ionospheric total electron content (TEC). The algorithm can run on a standard commercial chip. In this way, the cost, power consumption, size and data to be transferred of TEC monitor are reduced. To minimize the cache capacity needs and computational load, the algorithm collects the GNSS dual-frequency pseudorange and phase measurements in 20 minutes. The TEC, based on phase measurements, is fitted to the TEC derived from pseudorange measurements to achieve high-precision TEC along the line-of-sight path (slant TEC, STEC) within 20 minutes. A 5-min step is employed to compute the subsequent set of STEC. A thin-shell ionospheric model and VTEC polynomial model are used to construct the measurement equation of Kalman filter and acquire the quasi-real-time VTEC above the monitor. These VTEC values are compared with the results based on STEC from 1-day measurements. The results show that the quasi-real-time algorithm is effective. The algorithm is implemented on i.MX283 (Arm9™ Core).

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

, Available online , doi: 10.11728/cjss2024-0173

Abstract(534) PDF 1053KB(55)

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.

Application of improved model based on LSTM in ionospheric TEC forecast

, Available online , doi: 10.11728/cjss2024-0112

Abstract(224) PDF 706KB(22)

Abstract:
Ionospheric delay is one of the important error sources in global satellite navigation and positioning. Improving the prediction accuracy of ionospheric TEC is very important to improve the accuracy of satellite navigation and positioning. This paper combines the sliding window and long short-term memory neural network, uses the sliding window algorithm to continuously update the input sequence data set and test the accuracy of the model corresponding to different input sequence lengths. Finally, the input parameters are updated with 10% of the input data to construct a TEC prediction model. Verification results show that the proportion of absolute values of predicted residuals of the model less than 5TECu both in the calm period and magnetic storm period reached more than 85%, an increase of 49% and 71% compared with the corresponding values of the traditional LSTM model, and the root mean square error was 31% and 35% lower; the average absolute error of its forecast results was reduced by 25% and 32%.

Monitoring results of FY-3E satellite high-energy particle detector

, Available online , doi: 10.11728/cjss2024-0121

Abstract(215) PDF 4069KB(9)

Abstract:
High energy charged particles are one of the important factors affecting the safety of spacecraft and are an important part of space environment warning and forecasting. The measured data not only contributes to the prediction of space weather, but also helps to further understand the dynamic process of charged particles in radiation belts during disturbances. The FY-3E high-energy particle detector is used to monitor the radiation environment of high-energy electrons and protons, and can obtain high-energy electron and proton data in three directions of the satellite body (- Z upward direction, - X flight reverse direction, and+Y vertical orbital plane direction) ranging from 0.15 MeV to 5.7 MeV and from 3 MeV to 300 MeV respectively. The monitoring results reflect the differences and long-term variations in the flux intensity, distribution position, and distribution direction of high-energy protons and electrons, revealing the impact of disturbances, especially the extremely strong geomagnetic storm event in May 2024, on the environment of charged particles. The data results help to understand the long-term trends of high-energy particles in the satellite orbit, assist in studying the dynamic characteristics of the radiation belt, and the physical processes that may cause changes in the radiation belt. They can provide key environmental data support for orbit environment assessment, spacecraft radiation protection design, and on-board equipment safety, and provide a basis for conducting extreme event research.

A Two-Layer Hybrid Approach for Electromagnetic Spectrum Monitoring Satellite Mission Planning

, Available online , doi: 10.11728/cjss2024-0097

Abstract(131) PDF 1712KB(2)

Abstract:
Payload resources of electromagnetic spectrum monitoring (ESM) satellite are relatively rare. In order to execute monitoring missions effectively, it is necessary to allocate and adjuct payload resources dynamically. This paper presents a ESM satellite mission planning model which takes into account payload resources’ dynamic adjustment and respective constraints for mission execution. Then, a two-tier hybrid scheduling approach (TH-SA) is designed. The first layer of the TH-SA method uses a genetic algorithm to deal with sequences of tasks that are not dynamically adjustable, and the second layer is based on heuristic rules for planning tasks that can be dynamically adjusted. The advantages of mission dynamic adjustment are verified through simulation experiments, and results show that the proposed algorithm can effectively improve the performance of ESM satellite mission planning.

Optical Satellite Remote Sensing Image Orthographic Fusion Method based on Coprocessing of CPU and GPU in Domestic Cloud Platform

, Available online , doi: 10.11728/cjss2023-0069

Abstract(194) PDF 1565KB(3)

Abstract:
The processing efficiency of optical satellite remote sensing image orthographic fusion method based on coprocessing of CPU and GPU in domestic cloud platform is discussed systematically and is improved by data flow configuration and the intermediate data storage access optimization. The Phytium S2500 and NVIDIA A100 are used in the cloud platform to do the orthographic fusion experiment. The experiment results show that the method can greatly improve the fusion efficiency of optical satellite remote sensing image, and the acceleration ratio of the traditional x86 architecture CPU to the gpu is more than 14.3 times, and the corresponding processing time is reduced to less than 8.4s, and the GPU operation time is only 1s, which can meet the requirements of rapid orthographic correction of the large data of optical satellite remote sensing image.

Experimental research progress on fuel cells and electrolytic cells under unconventional gravity

, Available online , doi: 10.11728/cjss2024-0157

Abstract(533) PDF 786KB(9)

Abstract:
Fuel cells and electrolytic cells can provide energy support for long-term missions and bases in space, but different gravitational levels in space affect their performance, so experimental studies in unconventional gravity environments are necessary for the development and improvement of fuel cells and electrolytic cells for spaceflight. The experimental studies of fuel cells and electrolytic cells in unconventional gravity conditions are reviewed. The analyses and discussions show that the change of gravity level leads to the change of gas-liquid two-phase flow characteristics inside the fuel cell and electrolytic cell, which affects the performance differently. There is still a lack of experimental data on fuel cells in hypergravity and long-term microgravity, as well as unconventional gravity experiments on regenerative fuel cells. Fuel cell and electrolysis cell experiments under unconventional gravity conditions will not only help to promote the intersection of fluid physics and thermophysics with electrochemistry, but will also provide a data basis for the development of regenerative fuel cell systems in space.

Research on Calibration Techniques for Asymmetric Spatial Heterodyne Interferometers

, Available online , doi: 10.11728/cjss2024-0143

Abstract(143) PDF 1204KB(13)

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(123) PDF 1246KB(6)

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.

Lightweight Yolov5 algorithm target detection system based on space-grade NPU

, Available online , doi: 10.11728/cjss2024-0103

Abstract(270) PDF 989KB(10)

Abstract:
In order to solve the problem that the object detection algorithm based on deep learning is difficult to deploy on a space-based image processing platform with limited resources due to the complex network structure and excessive computational cost, this paper proposes a convolutional neural network acceleration design based on aerospace-grade neural network processor (NPU), and uses the improved Yolov5s network to realize fast image processing function on the NPU. The optimized network is iteratively trained on the GPU through the public dataset VOC, and the three parts of image processing are executed in parallel after the CPU-NPU parallel collaborative processing design, making full use of the limited computing and storage resources of the Yulong810A platform. Experiments show that the optimized network not only reduces the number of parameters by 82%, but also improves the accuracy compared with the original Yolov5s network, with an mAP value of 82.35%. After the algorithm is deployed on the Yulong810A on-board processing platform, the target detection speed reaches 41.67fps/s, which is more than twice the speed of the original Yolov5s network, and realizes a lighter and faster object detection system.

Analysis of COSMOS 1408 debris cloud evolution

, Available online , doi: 10.11728/cjss2024-0089

Abstract(189) PDF 1025KB(12)

Abstract:
There are more and more satellites and spacecrafts in earth orbit, and the density of near-earth space is increasing. According to statistics, the existing space debris mainly comes from about 640 space events. The study of satellite disintegration events is of great significance to maintain the safety of space environment. On November 15, 2021, Russia conducted an anti-satellite test and destroyed an abandoned satellite COSMOS 1408. The event produced a space debris cloud composed of about 1800 traceable debris. The height of the debris cloud is between 200 and 1400 km, and it continues to spread over time, threatening the safe operation of LEO satellites and spacecraft. Based on the TLE of COSMOS 1408 disintegration event debris released by SSN in the United States, this paper uses the SGP4 model to analyze the evolution of the space debris cloud, including the number of catalogs and temporal and spatial changes of the debris cloud, the changes of the main orbital parameters, and the impact of the disintegration debris on the space environment. Taking the four events that the debris threatened the ISS and forced the latter to maneuver to avoid the debris as an example, the evolution law and the impact are explored, and the evolution process and the impact of the COSMOS 1408 anti-satellite event space debris cloud are preliminarily restored.

, Available online , doi: 10.11728/cjss2024-0056

Abstract(103) PDF 1273KB(2)

Abstract:
The downlink data channels for a certain type of satellite include: satellite telemetry channel data and digital transmission channel data. The telemetry channel data refers to the S-band telemetry channel downlink data, and the digital transmission channel data refers to the digital transmission data engineering parameters. Based on the characteristics of digital transmission channel data with high rate, dual channels, and multiple application modes, a satellite status quantity processing and monitoring system is designed to meet the requirements of frame processing, analysis, and display of multi-channel data and high-rate digital transmission data engineering parameters, query, storage and abnormal alarm functions. This software system has been successfully applied to the mission operation control system of a certain type of satellite to meet the real-time monitoring of the satellite type platform and load.

Comparative analysis of four neural network methods for TEC modeling during ionospheric magnetic storms

, Available online , doi: 10.11728/cjss2024-0087

Abstract(195) PDF 5939KB(15)

Abstract:
The ionospheric total electron content (TEC) is an important parameter to describe the ionosphere. However, the study of TEC modeling mainly focuses on the calm period of the layer, and its application in the period of magnetic storms is relatively rare. To solve this problem, this paper uses LSTM, BiLSTM, CNN-LSTM-Attention and CNN-BiLSTM-Attention neural network models to train various spatio-temporal data of magnetic storm periods from 2002 to 2022, and obtains four TEC prediction models suitable for magnetic storm periods. Then, the accuracy and reliability of the four prediction models were verified by the measured TEC of two magnetic storms in 2023. The results showed that the CNN-BiLSTM-Attention model was significantly prior to the other three models in predicting the magnetic storm period, and the root mean square error (RMSE) was between 4.732 and 10.45 TECu. At the same time, there is a strong correlation with the reference value, the coefficient of determination (R²) is between 0.682 and 0.949, and the slope of the fitting function is closest to 1.

, Available online , doi: 10.11728/cjss2024-0092

Abstract(204) PDF 1075KB(15)

Abstract:
Based on the requirements for data preprocessing and distribution tasks of the Einstein Probe (EP) mission, as well as the processing needs for various types of data downlinked via X-band, S-band, VHF channel, and Beidou channel, a study was conducted on the key technologies for the EP satellite data preprocessing and analysis platform. Considering the data characteristics and processing requirements of the EP satellite payload data, algorithms were designed for level 0 data processing, level 1 data processing, and data product integrity interpretation based on observational organization. To meet the high timeliness requirements for the release of astronomical alert information in VHF data and Beidou short messages, different priority data preprocessing and distribution workflows were designed. Ultimately, a layered architecture design method was adopted to implement the EP satellite data preprocessing and distribution service platform. This platform is capable of automatically, efficiently, and accurately preprocessing, managing, and distributing various types of downlinked data from the EP satellite. System operation verification results show that the scientific data products processed by this platform are highly accurate, meeting the timeliness and accuracy requirements of EP satellite data preprocessing, and have good scalability.

Common mode error analysis of GNSS coordinate time series in northwest China based on MSSA algorithm

, Available online , doi: 10.11728/cjss2024-0072

Abstract(164) PDF 1472KB(42)

Abstract:
Aiming at the problem that the common mode error analysis of the vertical coordinate time series of the Global Positioning System (GNSS) in the three northwestern provinces is not comprehensive and in-depth, the MSSA algorithm is used as the theoretical basis to preprocess the data of 61 stations in the three northwestern provinces to improve the accuracy and integrity of the data, and on this basis, the common mode error of GNSS coordinate time series in the region is extracted and analyzed. The characteristic source of the common mode error (CEM) was explored by correlation analysis between the extracted CEM and the displacement time series caused by hydrologic load (NTOL), atmospheric load (NTAL) and non-tidal ocean load (HYDL). Through the extraction and analysis of common mode errors and the research on the source of error characteristics, the GNSS coordinate time series accuracy of the three northwestern provinces can be further improved, so as to provide higher precision data support for seismic displacement and crustal deformation research.

Uncertainty Evaluation of Atmospheric Temperature Retrieval using Rayleigh Lidar based on the Optimal Estimation Method

, Available online , doi: 10.11728/cjss2024-0081

Abstract(176) PDF 1043KB(33)

Abstract:
As a new retrieval method, the Optimal Estimation Method (OEM) is playing an increasingly important role in detecting the atmospheric environment by lidar. To characterize the reliability of the atmospheric temperature inversion results by lidar, the OEM uncertainty formula was derived and the sources of uncertainty was clarified. Based on the simulated echo photon profiles of the Rayleigh lidar, the middle atmospheric temperature and the corresponding uncertainty was calculated, which demonstrated that the main uncertainty sources in the OEM inversion process are the reference pressure uncertainty and noise uncertainty. Using the Monte Carlo method (MCM), the OEM uncertainty verification framework was established and the uncertainty values generated by different sources of uncertainty were verified. Results show that the uncertainty calculated by two different methods are consistent below the altitude of 85 km, proving the accuracy of the OEM uncertainty theories. In addition, temperature retrieval based on measured results by Rayleigh lidar was performed and the uncertainty analysis was accomplished, which paves the way for the applications of lidar in monitoring the atmospheric environment.

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(350) PDF 1291KB(51)

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(230) PDF 2230KB(7)

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(330) PDF 902KB(30)

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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