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Prepublish have been peer-reviewed and accepted, which are not yet assigned to volumes/issues, but are citable by Digital Object Identifier (DOI).
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Review of comprehensive utilization technology of lunar water ice resources
, Available online  , doi: 10.11728/cjss2022-0069
Abstract(13) PDF 2775KB(6)
Abstract:
As an important resource of the moon, research on the comprehensive utilization technology of lunar water ice is the cornerstone for the construction and operation of the lunar scientific research station and lunar base. Based on international exploration and research on lunar polar water ice, the occurrence and distribution characteristics of lunar water ice are described, along with the technical schemes, advantages, and disadvantages of mining, extraction, separation, purification, storage, and utilization of it. Given the future lunar scientific research station construction plan of China and the Artemis program of the US, appropriate regions, and technological schemes for comprehensive utilization of lunar water ice resources were identified, providing a critical reference for China's lunar polar water ice exploitation and utilization programs.
Research on Attitude maneuver and vibration of liquid-filled flexible spacecraft based on terminal sliding mode control
, Available online  , doi: 10.11728/cjss2022-0038
Abstract(2) PDF 2714KB(0)
Abstract:
The attitude control of rigid-liquid-flexible multi-body coupling spacecraft with unknown external disturbances and uncertain parameters is studied in this paper. The sloth of liquid fuel is equivalent to the spherical pendulum model, the flexible attachment is assumed to be Euler-Bernoulli beam, and the dynamics equation of spacecraft is established by Lagrangian method. Disturbance observer is designed to compensate lumped disturbance of the system. Then a fuzzy sliding mode control law is designed based on disturbance observer. Based on the original terminal sliding mode control, fuzzy control is adopted to improve the switching gain to suppress the jitter of the system. Numerical simulation results show that the proposed composite controller is feasible and effective.
Research Progress of Lunar In-Situ Water Production Techniques
, Available online  , doi: 10.11728/cjss2023-0006
Abstract(9) PDF 1135KB(4)
Abstract:
With the continuous advancement of deep space exploration, lunar exploration will be the first step for mankind to carry out interplanetary exploration and expand living territory. The lunar in-situ resource utilization will be a key technical approach to support manned exploration and long-term survival on the moon surface. Almost all space powers are carrying out continuous research on lunar in-situ water production technology, and China has also listed lunar surface in-situ water production as one of the key technologies for lunar exploration missions. Lunar in-situ water production can be mainly divided into two methods: polar water ice exploration/extraction and hydrogen reduction of lunar regolith. The water ice resources that had been detected are mainly located in the lunar polar region, with uneven distribution and great difficulty in extraction. Many different types of polar water ice exploration and extraction schemes have been put forward, but the actual effect needs to be verified by the lunar in-situ test. Hydrogen reduction of lunar regolith can used for in-situ water production, and its working conditions are not limited by the region, and its application scope is wide. However, there are some remaining technical limitations such as extreme reaction condition requirements and high energy consumption, which implies urgent demand to make breakthroughs in energy conservation and effective ingredient enrichment.
Modeling of temperature control system of space experiment high-temperature furnace based on XGBoost
, Available online  , doi: 10.11728/cjss2022-0061
Abstract(7) PDF 474KB(1)
Abstract:
In order to ensure that the scientific experiment system of high temperature material science experiment cabinet can successfully carry out space material science experiments, the temperature stability of high temperature material science experiments in space is required to be less than ± 0.25 ℃. In the face of such high temperature stability, a new solution is proposed: on the basis of experimental input and output data, a model equivalent to the high temperature furnace is determined to provide a basis for obtaining control parameters that meet the experimental requirements. In this paper, the interior of the high temperature furnace is regarded as a black box model. Based on XGBoost method, temperature zone 2 and temperature zone 3 of the high temperature furnace for Two types of sample experiments are modeled respectively, and the accuracy of the models can reach above 99.98%. Compared with the traditional modeling methods of transfer function and state space method, the model accuracy is still improved by 0.039 under the best performance of traditional methods, which provides important support for accurate control of high-temperature furnace temperature.
Analysis of Variation Characteristic of TEC at Kunming Region and Comparison with IRI-2020 During Descending Phase of Solar Activity
, Available online  , doi: 10.11728/cjss2022-0066
Abstract(2) PDF 558KB(1)
Abstract:
The variation characteristics of ionospheric Total Electron Content (TEC) at low latitude station, Kunming ( 24.7 °N, 102.9 °E ) from 2016 to 219 during the descending phase of solar activity and its comparison with the output by the latest version of the International Reference Ionosphere ( IRI-2020 ) are studied. The results show that the TEC has obvious semi-annual anomalies, with high value in spring and autumn while low value in summer and winter. The diurnal variation of daytime high value and nighttime low value is prominent, and the daily peak TEC appears between 6.5-8UT (about 13-15 LT ). The magnitude of annually average TEC decreases as the solar activity weakens, with the value of 48, 33, 27 and 24 TECu during 2016-2019, respectively. There is a significant correlation between peak TEC and F10.7 with a correlation coefficient of 0.86, and a weak correlation with the Ap index. The IRI-2020 can simulate well the seasonal variation of TEC at Kunming. However, there is a big difference between the output value and the observed result, which is overestimated in the daytime and underestimated in the nighttime. The root mean square deviation between model prediction and true value is mostly between 2-15 TECu, and the relative deviation percentage is mainly between -85%~50%. The results show that the prediction accuracy of IRI-2020 still needs to be improved.
On bubble departure radius in liquid oxygen tank of rocket propulsion system under microgravity
, Available online  , doi: 10.11728/cjss2023-0003
Abstract(5) PDF 1260KB(0)
Abstract:
Studying the bubble departure radius in the liquid oxygen tank under microgravity is the basis for the propellant boiling and heat transfer calculation of the launch vehicle propulsion system in orbit. Unlike regular or low gravity environments, the Marangoni effect becomes essential in microgravity. To calculate the bubble departure radius, Firstly, a bubble dynamics model is developed, including buoyancy, inertia, pressure, surface tension, drag, and Marangoni forces. Secondly, to solve the problem of the narrow application range of the existing Marangoni force formulas, a more accurate correction factor is fitted by numerical simulation. Consequently, the Marangoni force model is extended. Finally, using the physical parameters of saturated liquid oxygen at 0.3 MPa, a conventional working pressure for the liquid oxygen tank of the launch vehicle, the change of the total force with the radius and the departure radius with gravity are calculated, respectively. The results show that bubbles' departure behavior can be divided into three zones: microgravity zone, transition zone, and low gravity zone. The microgravity zone can form large bubbles of a centimeter or even meter scale, while the low gravity zone can only form tiny bubbles of 0.1 mm scale. Compared with the previous models, the model in this work can be applied to all three zones. Therefore, it comprehensively reveals the bubble departure characteristics in the liquid oxygen tank under microgravity. It can also provide theoretical support for analyzing the heat transfer characteristics in the liquid oxygen tank.
Satellite telemetry parameter prediction based on improved LSTM-Attention
, Available online  , doi: 10.11728/cjss2022-0057
Abstract(13) PDF 1242KB(7)
Abstract:

     Due to the complex space environment and the influence of the satellite itself, satellites in-orbit anomalies and failures occur from time to time. It is necessary for the ground system to predict the changing trend of future spacecraft performance through satellite telemetry parameters to ensure the safe operation of satellites. Aiming at the characteristics of satellite telemetry data with trends, local fluctuations and being easily affected by other environmental factors, this paper proposes a prediction model based on improved LSTM-Attention. The global model and local model are used to obtain the trend component and local fluctuation component of the telemetry sequence respectively. Moreover, the model will learn more sequence information by using the covariates that have an impact on predicting the target sequence, which improves the prediction accuracy. This model can provide both interval forecasting and point forecasting results for telemetry series. The real telemetry parameter data set of scientific satellite and the public data sets of time series are used for experimental verification. The results show that the method has achieved good results compared with benchmark algorithms.
A Time-Varying Volume Data Transfer Function for Interplanetary Numerical Simulation Data
, Available online  , doi: 10.11728/cjss2022-0011
Abstract(75) PDF 1194KB(58)
Abstract:
Understanding the interplanetary propagation of solar storms is the foundation of space environmental forecasting and services. The visualization of numerical model results is an important method to analyze the propagation dynamics process and verify the validity of the model. In order to facilitate the visual analysis of the model results, a transfer function design algorithm for volume rendering of time-varying data(TVTF) is proposed. The algorithm is based on the KNN background subtractor method to extract images including motion regions and motion subsets, and then use frequency-tuned (FT) salient region detection algorithm to detect coronal mass ejection(CME) in motion area images, and according to the CME detection results, a color inverse mapping algorithm is designed to find the boundary threshold between the CME and the background. Finally, the transfer function is adaptively adjusted based on the threshold to realize the fast 3D visualization of CME in the motion region at each time step. The experimental results show that the transfer function can adapt to the numerical model results in static and dynamic backgrounds. Compared with the linear transfer function, the occlusion of the line of sight direction is effectively avoided, the change of relative momentum is intuitively and automatically displayed, and the evolution process of CME in interplanetary space is traced. The extraction of local regions reduces data redundancy, and the process of adaptively adjusting the transfer function by automatically analyzing the data with the help of algorithms avoids the inefficiency of manual adjustment.
Research development and technical difficulties of ultra-LEO spacecraft
, Available online  , doi: 10.11728/cjss2022-0010
Abstract(142) PDF 1598KB(26)
Abstract:
Ultra LEO spacecraft has become a hot research field for a wide range of application in military, remote sensing, scientific research, etc. Due to the special space environment of ultra-low orbit, many technical difficulties need to be solved, mainly focusing on atmospheric environment prediction, aerodynamic, aerothermal and so on. This paper introduces the typical mission of ultra LEO spacecraft, the main atmospheric model and inversion method, the aerodynamic design of ultra LEO spacecraft and the stability control method under aerodynamic interference, the aerodynamic thermal protective material and the variable switching technology of thermal insulation and heat dissipation. This review is helpful to promote the key technology research and test demonstration of ultra LEO spacecraft, turning the ultra LEO spacecraft from test mission to space application mission as soon as possible.
Orbit determination analysis of interplanetary transfer section of Mars probe
, Available online  , doi: 10.11728/cjss2022-0008
Abstract(54) PDF 859KB(7)
Abstract:
Tianwen-1 is the first chinese probe to realize interplanetary flight between Earth and Mars. During the 6.5-month interplanetary transfer flight, it experienced four midway corrections and one deep space maneuver control. In this paper, the dynamic model during deep space exploration is analyzed, and the principle of celestial center conversion during transfer flight is formulated. It is necessary to replace the celestial center with the sun after leaving the earth's influence sphere; The use of planetary ephemeris is analyzed, and it is determined that the use of de436 ephemeris has the least impact on orbit determination; an accuracy evaluation method based on daily iterative orbit determination strategy is developed. Based on the analysis of measured data, it is shown that the orbit determination position error in interplanetary transfer section is better than 2km, and the velocity error is better than 20mm / s (1 σ).
Responses of the middle and upper atmospheric wind to geomagnetic activities
, Available online  , doi: 10.11728/cjss2022-0016
Abstract(86) PDF 1710KB(32)
Abstract:
Responses of the middle and upper atmospheric (80-100 km ) wind to geomagnetic activities have been investigated using neutral wind data from 2012 to 2018 years, which were observed by Mohe, Beijing and Wuhan Meteor radars. Daily averaged wind data for geomagnetic quiet condition (Kp ≤ 2) and geomagnetic disturb condition (Kp ≥ 4) were chosen for comparison, and the variation characteristics of wind during geomagnetic disturbances were obtained. The observations show that the influence of geomagnetic activity on zonal wind varied with seasons and latitudes. For zonal wind, the effect of geomagnetic activity at higher latitudes tended to be more westerly wind in the upper mesosphere and more easterly wind in the lower thermosphere, and the differences between disturbed and quiet conditions were on the order of 3 m/s; while for the lower latitudes, it tended to be more easterly wind in the 80-100 km region, and the influence were about 5 m/s. In spring, the three stations had similar tendencies, and had no latitude differences. But the easterly wind in the middle atmosphere became stronger with the decrease of latitude in summer/winter. The effect of geomagnetic activities on the meridional wind had seasonal differences. The influence of geomagnetic activities in spring and winter was stronger than that in summer and autumn. In winter, the effect of geomagnetic activity on the meridional wind in middle and low latitudes was stronger than that in higher latitudes. According to the calculation results, the influence on zonal wind was about 5 m/s to 10 m/s, and on meridional wind was about 3 m/s to 5 m/s. The impact of geomagnetic activities on MLT wind can penetrate down to about 80 km. At this height, the influence on zonal wind was the strongest in spring, reaching 8 m/s, and on meridional wind was the strongest in spring/winter, reaching 5 m/s.
, Available online  , doi: 10.11728/cjss2022-0027
Abstract(57) PDF 592KB(21)
Abstract:
X-ray occultation is a common astronomical phenomenon. The new technique of atmospheric density retrieval based on X-ray occultation sounding realizes the retrieval of atmospheric density by processing occultation observation data of high-energy X-ray celestial radiation source, which is a new method involving interdisciplinary. This paper briefly introduces the application requirements of X-ray occultation sounding, the new technique of atmospheric density retrieval based on X-ray occultation is analyzed and demonstrated, and mainly introduces the research progress and methods of atmospheric density retrieval based on X-ray occultation, and analyzes and discusses the advantages of atmospheric density retrieval based on X-ray occultation. And the future development direction and application research of X-ray occultation sounding are prospected.
Study on ultraviolet aurora image for prediction of auroral electrojet index
, Available online  , doi: 10.11728/cjss2022-0033
Abstract(20) PDF 1436KB(3)
Abstract:
Aiming at the problems of difficult observation, high acquisition cost and different time scales for the input data of traditional auroral electrojet (AE) index prediction models, this paper proposes a prediction model based on ultraviolet aurora images. In this paper, the ultraviolet aurora images of the Polar satellite are used as the data base, and the longitude and latitude distribution characteristics of Aurora intensity is extracted by the grid feature extraction method, which are input into the generalized regression neural network to predict the AE index. Based on the research on the relationship between the auroral electrojet system and the spatial distribution of auroral power, the contribution of the geomagnetic latitude and longitude distribution characteristics of auroral power to the AE index was further explored. The experimental results of the prediction model show that the method of predicting the AE index with the aurora image data is feasible, and compared with the traditional prediction model, the model in this paper is superior to the traditional prediction model in the evaluation criteria of root mean square error RMSE, average relative variance ARV and determination coefficient R2.
Image Feature Extraction and Matching of Augmented Solar Images in Space Weather
, Available online  , doi: 10.11728/cjss2022-0064
Abstract(36) PDF 1446KB(3)
Abstract:
We used augmented solar images to research the adaptability of four representative image extraction and matching algorithms in space weather domain, including the scale-invariant feature transform algorithm, speeded-up robust features algorithm, binary robust invariant scalable keypoints algorithm, and oriented fast and rotated brief algorithm. We estimated the performance of these algorithms in terms of matching accuracy, feature point richness and running time. We concluded that no algorithm achieved high accuracy while keeping low running time, and all algorithms are not suitable for image feature extraction and matching of augmented solar images. To solve this problem, we proposed an improved method by using two-frame matching to utilize the accuracy advantage of the scale-invariant feature transform algorithm and the speed advantage of the oriented fast and rotated brief algorithm. Furthermore, we applied our method and the four representative algorithms to augmented solar images. The results of our application experiments proved that our method achieved a similar high recognition rate to the scale-invariant feature transform algorithm which significantly higher than other algorithms, and obtained similar low running time to the oriented fast and rotated brief algorithm which significantly lower than other algorithms.
Recent Progress and Development Trend of Solid Combustion Research for Manned Space Exploration
, Available online  , doi: 10.11728/cjss2022-0049
Abstract(48) PDF 3199KB(13)
Abstract:
The understanding of solid material flammability in the specific use environment is of practical importance for manned spacecraft fire safety, and the relevant fire safety concerns in spacecraft have served as one of the primary motivations for microgravity combustion research. In recent years, the various space powers have paid continuous attention to the burning characteristics of solid materials and the corresponding application to spacecraft safety. It seems that a renewed interest in such a research field is arising, while distinct features and development trends could be identified. This paper reviews the research progress and latest results on microgravity solid combustion in recent ten years. Overall development trends of the field and future directions of research work are also discussed, hoping to provide useful reference for further research.
Research on Thermodynamic Characteristics of Cryogenic Liquid Krypton Tank in Microgravity
, Available online  , doi: 10.11728/cjss2022-0040
Abstract(27) PDF 1656KB(4)
Abstract:
The cryogenic liquid krypton tank will be in microgravity environment for more than several hundred seconds during MECO(Main Engine Cut-off)phase, its internal heat transfer and phase change have an important impact on the performance of the storage and supply system of the large orbit transfer vehicle. Establishing a CFD model of liquid krypton tank, the effects of gravity level, initial liquid krypton temperature and initial filling rate on the thermal stratification and pressure variation of liquid krypton tank in microgravity were studied by using VOF method and Lee gas-liquid phase change theory. The results show that, in the microgravity conditions, the tank pressure rise rate are lower than in the ground condition, the pressure rise rate of tank in g0 is 1.843 times, 1.98 times and 2.04 times of 10-4g0, 10-5g0 and 10-6g0 respectively, the degree of temperature stratification (2-3 K) is much lower than that of ground conditions (90 K). Under different initial liquid krypton temperatures, the tank pressure decreases first and then increases with time, and the lower the initial liquid krypton temperature is, the smaller the pressure rise rate of the tank is. There is a critical initial fill ratio of the tank in microgravity, when the initial fill ratio is > 70%, the pressure rise rate increases with the increase of the initial fill ratio, and when the < 70%, the pressure rise rate of the tank decreases with the increase of the initial fill ratio.
Satellite Anomaly Detection Method Based on Parameter Adaptive Optimization Clustering
, Available online  , doi: 10.11728/cjss2022-0054
Abstract(59) PDF 772KB(14)
Abstract:
  Real-time monitoring of satellite status and anomaly detection are conducive to ensuring the safe and stable operation of satellites. Clustering analysis has proved effective in many engineering anomaly detection problems. However, the quality of clustering is highly sensitive to parameters, and there is no convenient parameter selection method for now. To realize the adaptive selection of clustering parameters, this paper treats parameter adjustment as a single-objective optimization problem and introduces intelligent optimization algorithm to solve it. Accordingly, the UMOEAsII_BIRCH algorithm is proposed by combining BIRCH (Balanced Iterative Reducing and Clustering using Hierarchies) and UMOEAs-II (United Multi-operator Evolutionary Algorithms-II). Based on the real data of a space science satellite, the telemetry data containing point anomalies are simulated and used for anomaly detection effect test after preprocessing. The traditional clustering algorithms K-Means, MeanShift, OPTICS, DBSCAN, BIRCH and the algorithm proposed in this paper are selected for experiments to compare the accuracy, recall, F1-score and false positive rate of anomaly detection. The results demonstrate that the UMOEAsII_BIRCH algorithm outperforms other algorithms in anomaly detection, and the F1-score can reach 0.861017. Meanwhile, compared with grid search, the proposed algorithm requires less manual intervention and achieves automatic selection of optimal clustering parameters, in line with the improvement expectations.
Optical observations and its application on orbit determination for 2016HO3 exploration
, Available online  , doi: 10.11728/cjss2022-0026
Abstract(35) PDF 1123KB(5)
Abstract:
According to the upcoming Chinese asteroid mission, we did a full simulation analysis on the optical navigation according to three types of optical observations based on on-board camera. We built the dynamic model of the asteroid exploration firstly, and then selected the celestial bodies we could observe during mission, which help to determine the observe scheme and direction of the camera. Based on such setting, we simulated the observations and did the orbit determination. The results indicates that when the observable periods extends to 100h, the position error of the spacecraft could reaches to 50 km, which could meet the navigation requirement, but the position and velocity components in X and Y directions have strong autocorrelation. Meanwhile, the results also show that the orbit determination accuracy based on single observation type data is 3-4 orders of magnitude lower than that of joint observation. The third-type observation has a significant contribution to the orbit determination with respect to another two kinds of observations, which indicates that the use of the solar system bodies for 2016HO3 exploration is more helpful to constrain the spacecraft position. This paper will provide some reference for the autonomous navigation technology of China's future asteroid exploration missions.
An FPGA-implemented method for real-time multi-dimensional feature extraction of sequence image targets
, Available online  , doi: 10.11728/cjss2022-0014
Abstract(105) PDF 2839KB(69)
Abstract:
The prerequisite of target detection and tracking is to model and represent the target based on multi-dimensional features extracted from the target region. The traditional target feature extraction needs to connect the target region first and then must calculate the target feature, which has still room for improvement in real-time. An advantage of the new method based on the synchronous calculation of pixel-connected domain markers and target features is that the target features can be output when the target region is connected. The process establishes a feature transfer mechanism, creates a marker table, a marker mapping table, and a feature attribute table simultaneously when scanning images, and uses the marker mapping table to associate the marker table and the feature attribute table. The marker merging and feature attribute transfer calculation are performed synchronously at the time of region adjacency, which ensures the real-time target feature extraction. As a result, the method proved to be effective because of an implementation scheme based on an FPGA system design. Simulation test results show that this method has several outstanding features: the time of connected domain markers is close to the theoretical minimum; the storage of images utilizes the circular buffer with low resource consumption; marking and computation are processed in parallel flow to improve detection and tracking efficiency; multi-target features are tested and verified to be accurate, which can effectively support subsequent target tracking detection; and it has theoretical and practical values.
BDSBAS performance evaluation analysis
, Available online  , doi: 10.11728/cjss2022-0039
Abstract(45) PDF 1402KB(10)
Abstract:
Satellite-based augmentation is an important means to support civil aviation route operations and terminal area operations. In order to verify whether the BeiDou Satellite-Based Augmentation System (BDSBAS) complies with the International Civil Aviation Organization (ICAO) signal-in-space performance requirements , to evaluate and analyze it. In this paper, the actual broadcast ephemeris, precise ephemeris and BDSBAS enhanced messages are used as experimental data. The performance of BDSBAS was evaluated and analyzed based on six indicators, point, broadcast time and ionospheric delay error. The results show that the GPS satellite orbit error, satellite clock error and space signal ranging error after BDSBAS enhancement are improved compared with those before enhancement; BDSBAS grid ionospheric effective points cover China and surrounding areas; ionospheric delay broadcast interval reaches ICAO Requirements for precise differential positioning; the ionospheric delay has a large error in the range of 0° to 15°N, and the reliability is poor; in the range of 20°N-55°N, the error is small and the reliability is good.
Response mechanism of tribological properties of WS2 film under different ambient thermal shock
, Available online  , doi: 10.11728/cjss2022-0037
Abstract(31) PDF 1169KB(6)
Abstract:
Al: WS2 films were prepared by magnetron sputtering technology. In order to investigate the response mechanism of the tribological properties of Al: WS2 film under different ambient thermal shock, the thermal shock tests of -100~+250℃ in vacuum, nitrogen and oxygen were carried out using the temperature altering vacuum tribometer developed by us, and the structure, composition and tribological properties of Al: WS2 films after thermal shock were mainly studied. It was found that the columnar crystal of Al: WS2 film grows, S content decreases, part of WS2 is oxidized to WO3, and the hardness of film increases after thermal shock. Thermal shock under vacuum and oxygen deteriorates the tribological performance of Al: WS2 films. However, after thermal shock under nitrogen atmosphere, WO3 appears on the surface of Al: WS2 film and was incorporated into the crystal structure, leading to the increase of size of interlayer and the decrease of friction coefficient. Due to the obstruction of a layer of WO3 generated on the surface, the wear life of Al: WS2 film increases. Therefore, thermal shock under nitrogen can improve the tribological performance of Al: WS2 film.
, Available online  , doi: 10.11728/cjss2022-0030
Abstract(50) PDF 2033KB(10)
Abstract:
In this paper, the equatorial plasma bubbles (EPBs) of March 30th, 2014 were studied using airglow images of 630 nm emission and observations of VHF radar over Hainan Fuke Station (19.5°N, 109.1°E) from the Meridian Project, digisonde over Hainan Sanya Station (18.4°N, 109.6°E), and data of C/NOFS. In this case, the morphological features and evolution processes in detail were analyzed. The results showed that there were a group of EPBs during the night. Nine EPBs were observed in this case. These EPBs occurred after sunset, lasting after midnight. The lifetime is about eight hours (from ~20: 15 LT to ~ 04: 15 LT). These EPBs moved from west to east during the night. Their longitudinal ranges are more than 1200 km. East-west ranges of EPB group are more than 2900 km. Besides, two EPBs (b5 and b6) showed a merging process. Portion of b6 merged into the b5 and then formed one EPB. When those plasma bubbles were observed by the all-sky imager, corresponding range spread F and plume irregularities also were simultaneously observed by the digisonde and VHF radar, respectively. Meanwhile, observation from C/NOFS also showed plasma depletion. Evolutions of these EPBs were simultaneously observed by optical equipment (all-sky imager) and radio equipment (VHF radar and digisonde) of ground-based measurements, and C/NOFS satellite.
Design and Verification of Scientific Exploration Mode of Zhurong Mars Rover
, Available online  , doi: 10.11728/cjss2022-0022
Abstract(58) PDF 1322KB(10)
Abstract:
To obtain as much exploration data as possible with limitations of low communication capability and insufficient energy, Zhurong Mars rover payloads need to improve scientific exploration efficiency. There are two major operating conditions for the payloads, conducting roving exploration when the rover moves and in situ exploration when the rover stops. Serval high-efficiency payload exploration modes were developed for those two conditions. The exploration mode, working with autonomous control based on work mode command set, solved the problem of multiple payloads performing collaborative scientific exploration under resource shortage conditions. The Zhurong Mars rover has successfully completed the scheduled exploration mission. All scientific exploration modes have been verified. The results demonstrate that the exploration modes are suitable and effective, and can meet the requirements of conducting safe, autonomous and efficient scientific exploration.
An Improved HVQ Algorithm for Compression and Rendering of Space Environment Volume Data with Multi-variables
, Available online  , doi: 10.11728/cjss2022-0020
Abstract(68) PDF 623KB(2)
Abstract:
Space environment simulation can produce several correlated variables at the same time. For space environment volume data with multi-correlated variables, based on HVQ-1d method we propose a further improved HVQ method by compositing variable-specific levels to reduce the redundant information among these variables. We further take advantage of progressive rendering based on GPU for real-time interactive visualization. The results of our experiments prove that the method proposed in this paper can pays the least cost of quality at compression and provides satisficed fidelity while ensuring interactive rendering speed in space environment domain. The proposed method can also be applied in other domains.
Comparative Study between the deriving ionospheric foF2 from nighttime OI 135.6nm emission and ionosonde observations
, Available online  , doi: 10.11728/cjss2022-0018
Abstract(67) PDF 849KB(53)
Abstract:
During the nighttime, the 135.6nm spectral line is excited by the radiation recombination process of F region O+ and e- and the mutual neutralization process of O+ and O- in the ionosphere. There is a strong correlation between the intensity of the spectral line and the maximum electronic density of ionospheric F2 layer (NmF2). Based on the physical model in which the OI 135.6 nm emission is proportional to the square of NmF2, we establish a retrieval algorithm suitable for different longitude and latitude, local time, season and solar activity. In this paper, the critical frequency of ionospheric F2 region (foF2) was retrieved from 135.6nm emission observed by the Special Sensor Ultraviolet Spectrographic Imager (SSUSI) instrument on board the Defense Meteorological Satellite Program (DMSP), and then the estimated results were compared with the detection results of ground-based ionosonde. As the results show, during the high-solar activity year (2013), the data with relative error less than or equal to 20% accounted for 92.99%, and the average relative error was about 7.18%. During the low-solar activity years (2017), the data with relative error less than or equal to 20% accounted for 80.76%, and the average relative error was about 13.02%. Finally, we analyzed the difference of retrieval accuracy of the algorithm during the high and low solar activity years.
Spectrum Sensing Algorithm for Cognitive Satellite Communication Based on Bi-LSTM and Bayesian Likelihood Ratio Test
, Available online  , doi: 10.11728/cjss2022-0017
Abstract(118) PDF 784KB(84)
Abstract:
With LEO mega satellites constellation coming into operation, the available spectrum resources are more overcrowded. To improve spectrum utilization, cognitive satellite communication technology composed of GEO relay satellites and LEO satellites has become an important choice. The most critical step in the cognitive satellite communication scenario is the spectrum sensing technology used to quickly determine the presence or absence of the primary user. Since most current spectrum sensing algorithms are model-driven, they rely heavily on the assumed statistical model for their detection performance, which makes it more difficult to model and deploy in variable satellite communication scenarios. In this paper, we firstly analyze the signal-to-noise ratio fluctuations during LEO satellite transit, and secondly propose a spectrum sensing algorithm combining bidirectional long short-term memory network and Bayesian likelihood ratio test for this variable channel environment. The algorithm does not require any a priori knowledge of PU signals and can automatically learn features from PU signal data and make decisions. Simulation results show that the proposed algorithm still achieves 83% detection performance at a signal-to-noise ratio of -14 dB and consistently outperforms convolutional neural networks, multi-layer perceptron, and model-driven energy detection-based algorithms.
, Available online  , doi: 10.11728/cjss2022-0035
Abstract(45) PDF 1846KB(21)
Abstract:
In this study, based on the Rayleigh lidar echo photon signal of the middle atmosphere, the optimal estimation method is used to retrieve the atmospheric temperature profile. The forward model is constructed by using the Rayleigh lidar equation, and the covariance matrix of the measured signal is determined according to the Poisson counting characteristics of the photodetector. The temperature profile of the atmospheric model is selected as the prior state information, on the basis of which the cost function is determined. Finally, the Levenberg-Marquardt optimization algorithm is used to optimize the cost function. The average kernel matrix is used to evaluate the contribution of real information to the inversion results, and the uncertainty of the inversion results is calculated. The results show that the forward model can correctly describe the real physical process of Rayleigh lidar detecting atmosphere. In the area where the signal-to-noise ratio of the echo photon signal is high, the real information accounts for the main contribution to the inversion results, and the vertical resolution is small. The uncertainty of temperature inversion in the range of height below 90km is between 0K and 10K.
Hardware Acceleration of YOLOv5s Network Model Based on Aerospace-Grade FPGA
, Available online  , doi: 10.11728/cjss2022-0044
Abstract(45) PDF 675KB(8)
Abstract:
With the rapid development of remote sensing engineering technology in our country, the acquisition of remote sensing image data has increased sharply, and the complexity of the image background has also increased. However, the traditional remote sensing image target detection algorithm has low accuracy and weak generalization ability. The accuracy of CNN is gradually difficult to meet the requirements. Aiming at this problem, a processing architecture based on aerospace-grade FPGA for forward inference acceleration of convolutional neural networks is proposed, and the YOLOv5s network model is selected as the benchmark algorithm for the design of the processing architecture. Since the main body of YOLOv5s is composed of a large number of convolutional layers, the center of gravity of the accelerator architecture design is located in the convolutional layer. In the design of the architecture, the parallel expansion of input channels and output channels and the optimization strategy of data pipeline control are used to effectively improve the Real-time processing performance in the inference phase. The experimental results show that when using this processing architecture to accelerate the inference stage of YOLOv5s, the operating frequency of the convolution module can reach 200MHz, its computing performance is as high as 394.4GOP/s, the power consumption of the FPGA is 14.662W, and the average computing efficiency of the DSP calculation matrix It is as high as 96.29%, indicating that using FPGA for hardware acceleration of convolutional neural networks in on-board platforms with limited resources and power consumption has significant advantages.
Automatic Identification of Space hurricane Based on Transfer Learning
, Available online  , doi: 10.11728/cjss2022-0031
Abstract(44) PDF 1461KB(6)
Abstract:
Space hurricane is a bright spot-like auroral structure in the polar cap region, which visually characterizes a solar wind energy injection phenomenon comparable to a magnetic storm during the geomagnetic calm period. In this paper, we propose an automatic Space hurricane identification model based on EfficientNetB2 and Transfer Learning, and validate the effectiveness of the model in DMSP/SSUSI observations from 2005-2021 with an accuracy of 97.8%. The results show that the method can be used to automatically identify Space hurricane events from a large amount of satellite-based auroral observation data.
Development of an X-ray Modulation Characterization System for HXI payload onboard ASO-S Mission
, Available online  , doi: 10.11728/cjss2022-0013
Abstract(72) PDF 1486KB(54)
Abstract:
The Advanced Space-based Solar Observatory is scheduled to be launched in fall of 2022. The ASO-S carries three payloads to fulfill its science objects. As a key instrument onboard, the Hard X-ray Imager aims at observing solar flares after launch. HXI adopts spatial modulation technique using 91 pairs sub-collimator as Fourier units. However, it is quite hard to calibrate modulating parameters on ground through lack of parallel X-rays in lab. This paper introduces design, fabrication as well as integration of X-ray Modulation Characterization System last year. Application of X-ray beam test was applied for HXI subsequently. Discussion on test results was presented in the end which indicated well performance in orbit.
, Available online  , doi: 10.11728/cjss2022-0028
Abstract(68) PDF 1071KB(15)
Abstract:
Distribution of the ionospheric irregularities scattering occurrence rate were investigated using data from March, 2018 to November, 2019, which were observed by the SuperDARN Jiamusi and Hokkaido East radars. We statistically compared the irregularities scattering occurrence rate in geomagnetic quiet period (Kp<3) and geomagnetic disturbance period (Kp>3), obtained the variation characteristics of the irregularities scattering occurrence rate depending on magnetic latitude and MLT, and analyzed the characteristics of the occurrence rate enhancement phenomenon in the dusk side and dawn side. The enhancement of the dusk side occurrence rate was widespread in the range of 45°-65ºMLAT, and the occurrence rate in the subauroral region was significantly enhanced during the magnetic disturbed period. The enhancement of the dawn side occurrence rate is mainly distributed in areas below 55ºMLAT, and the enhancement of the geomagnetic disturbance has a weak effect on it except in autumn. The day side occurrence rate in middle magnetic latitude is less affected by geomagnetic disturbance.
Analysis of the main magnetic field order of the global geomagnetic field model based on Bayesian evidencen
, Available online  , doi: 10.11728/cjss2022-0009
Abstract(60) PDF 604KB(60)
Abstract:
This paper uses Bayesian inference to compare the global main magnetic field models, and compares the model order of data preference based on Bayesian evidence. It provides a statistical basis for the order selection of the main magnetic field.Using the Swarm satellite data, Using the Swarm satellite magnetometry data, we estimate the evidence for different orders of the main magnetic field model.The results show that in the order of the main magnetic field from 0 to 20, order N=12 has the global best evidence. Referring to the threshold interval given by Jefrrey's scale, the data preference for order N=12 is significantly better than other orders.the results match the power spectrum analysis of the 14th order spherical harmonics.

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