Table of Content

    15 March 2021, Volume 41 Issue 2 Previous Issue   
    Research Articles
    In Situ Detection of the Solar Eruption: Lay a Finger on the Sunormalsize
    LIN Jun, HUANG Shanjie, LI Yan, CHONG Xiaoyu, ZHANG Shenyi, LI Mingtao, ZHANG Yiteng, ZHOU Bin, OUYANG Gaoxiang, XIANG Lei, DONG Liang, JI Haisheng, TIAN Hui, SONG Hongqiang, LIU Yu, JIN Zhenyu, FENG Jing, ZHANG Hongbo, ZHANG Xianguo, ZHANG Weijie, HUANG Min, Lü Qunbo, DENG Lei, FU Huishan, CHENG Xin, WANG Min
    2021, 41 (2):  183-210.  doi: 10.11728/cjss2021.02.183
    Abstract ( 126 )   PDF (6315KB) ( 115 )   Save
    This paper is to introduce a proposed deep space mission, which aims to perform in situ detection of the central structure, namely the magnetic reconnection current sheet, which drives the large scale eruption on a star. The main focus of this mission is on the fine physical characteristics of the large scale magnetic reconnection taking place on the Sun, our nearest star, revealing the secret of the most violent energy release process, also known as the solar storm, in the solar system. The scientific goal of this mission, magnetic reconnection, is a kernel process of energy conversion occurring in the magnetized plasma in the universe, and has long been a fairly important research topic or even research area in solar physics, space science, plasma physics, and the related fields. In situ detection enhances the spatial resolution of the instruments used on the Earth 5~20 times, will provide us extra-clear images of the Sun and the related information. We are thus able to study, to learn, and to understand the Sun on an unprecedented platform, and further resolve the long-standing puzzle in the solar community regarding the fine physical property of the kernel process driving the solar eruption, as well as that of the corona heating.
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    An Event Horizon Imager (EHI) Mission Concept Utilizing Medium Earth Orbit Sub-mm Interferometry
    2021, 41 (2):  211-233.  doi: 10.11728/cjss2021.02.211
    Abstract ( 293 )   PDF (5803KB) ( 139 )   Save
    Submillimeter interferometry has the potential to image supermassive black holes on event horizon scales, providing tests of the theory of general relativity and increasing our understanding of black hole accretion processes. The Event Horizon Telescope (EHT) performs these observations from the ground, and its main imaging targets are Sagittarius A* in the Galactic Center and the black hole at the center of the M87 galaxy. However, the EHT is fundamentally limited in its performance by atmospheric effects and sparse terrestrial (u,v)-coverage (Fourier sampling of the image). The scientific interest in quantitative studies of the horizon size and shape of these black holes has motivated studies into using space interferometry which is free of these limitations. Angular resolution considerations and interstellar scattering effects push the desired observing frequency to bands above 500 GHz.
    This paper presents the requirements for meeting these science goals, describes the concept of interferometry from Polar or Equatorial Medium Earth Orbits (PECMEO) which we dub the Event Horizon Imager (EHI), and utilizes suitable space technology heritage. In this concept, two or three satellites orbit at slightly different orbital radii, resulting in a dense and uniform spiral-shaped (u,v)-coverage over time. The local oscillator signals are shared via an inter-satellite link, and the data streams are correlated on-board before final processing on the ground. Inter-satellite metrology and satellite positioning are extensively employed to facilitate the knowledge of the instrument position vector, and its time derivative. The European space heritage usable for both the front ends and the antenna technology of such an instrument is investigated. Current and future sensors for the required inter-satellite metrology are listed. Intended performance estimates and simulation results are given.
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    Space Physics
    Magnetopause Indentation Induced by the Magnetosheath Fast Flowormalsize
    SONG Xiaojian, ZUO Pingbing, ZHOU Zilu
    2021, 41 (2):  234-241.  doi: 10.11728/cjss2021.02.234
    Abstract ( 70 )   PDF (4131KB) ( 50 )   Save
    Recent studies indicated that the magnetopause indentation plays an important role in magnetosphere-ionosphere coupling. Confirmation of magnetopause indentation requires joint observations with multiple satellites. So far, there have been few magnetopause indentation events reported. In this paper, a case of magnetopause indentation induced by fast magnetosheath flow is reported with multiple spacecraft analysis based on the observations of five THEMIS probes. During the interval from 10:00 UT to 10:45 UT on 21 July 2007, when the five THEMIS probes are located near the subsolar magnetopause, a fast anti-sunward flow (with a velocity of 400km·-1) was observed in the magnetosheath just before THEMIS crossed the magnetopause to the magnetosphere. A magnetopause local indentation event was identified by comparing the nominal magnetopause and the tangential magnetopause plane calculated using the MVA method. In order to explore the origin of this magnetosheath fast flow, solar wind data observed by WIND satellite at L1 point were analyzed. It is found that the solar wind is very stable during this period. The Interplanetary Magnetic Field (IMF) is mainly radial and the component of the north-south direction is very small. It is speculated that the generation of this magnetosheath fast anti-sunward flow may be related to the radial IMF.
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    Effect of Plasma Sheath on the Design of Electric Field Instrument Detecting Magnetosheathormalsize
    LIU Ji, ZHOU Bin, LI Lei, FENG Yongyong, ZHANG Yiteng, YIE Jiancheng
    2021, 41 (2):  242-249.  doi: 10.11728/cjss2021.02.242
    Abstract ( 64 )   PDF (2054KB) ( 37 )   Save
    The distribution of plasma potential and density around spacecraft is affected by the coupling of spacecraft and plasma, resulting in disturbing the detection of space electric field. In this paper, Spacecraft Plasma Interaction Software (SPIS for short) is used to provide a reference to design the electric field instrument detecting magnetosheath on future missions. The interaction of plasma with the spacecraft platform and the probe is simulated to investigate the thickness of plasma sheath and the relationship between current and voltage drop under different plasma conditions. Our results indicate that the thickness of plasma sheath covered spacecraft is smaller than the Debye radius, and this difference is larger at higher temperature conditions caused by photoelectrons and secondary electrons. Moreover, the current collected by the probe at a different voltage drop is also simulated. The simulated results show that the influence of current disturbance on measuring potential can be reduced by the probe with a bias current. Furthermore, the estimated optimum bias current is also listed corresponding to the detected region.
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    Local Time Differences in the Ionospheric Electromagnetic Ion Cyclotron Waves during Storm Timeormalsize
    SUN Luyuan, WANG Hui, HE Yangfan
    2021, 41 (2):  250-260.  doi: 10.11728/cjss2021.02.250
    Abstract ( 78 )   PDF (3824KB) ( 33 )   Save
    By using high-resolution (50 Hz) magnetic field observations from Swarm constellation, the temporal and spatial characteristics of Electromagnetic Ion Cyclotron (EMIC) waves in different local time sectors at mid-latitudes are investigated during the magnetic storm period of 16-25 March 2015. There are comparable number of EMIC wave events in the dawn and dusk sectors, while there are more EMIC wave events in the pre-noon sector than in the pre-midnight sector. The duskside preference is related to the plasmaspheric plume, while the dawnside preference is related to the enhanced solar wind dynamic pressure and dense cold plasma. The wave frequency in the dawn and pre-noon sectors is higher than that in the dusk and pre-midnight sectors, implying the local time difference in the source location and the ion composition. Most of the duskside events occur in the early recovery phase, while the dawnside events occur in the late recovery phase. The time difference comes from the time required for the westward drift of energetic ions and local time difference in the plasmapause position. H+ band waves are mainly found in the 06:00 MLT-10:00 MLT sector, while He+ band waves are mainly confined in the 18:00 MLT-22:00 MLT sector. There is no H+ band but a two band (He+ and O+) EMIC wave during the storm main phase, indicating the role of the dense oxygen ion in inhibiting the H+ band in the inner magnetosphere.
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    Impact of Geomagnetic Storms on Ionosphere Variability and Precise Point Positioning Application in High Latitudes of the Northern Hemisphereormalsize
    WANG Ge, WANG Ningbo, LI Zishen, ZHOU Kai, LIU Ang
    2021, 41 (2):  261-272.  doi: 10.11728/cjss2021.02.261
    Abstract ( 72 )   PDF (6134KB) ( 27 )   Save
    Based on the ionospheric scintillation data of the Canadian High Arctic Ionospheric Network (CHAIN), the variation characteristics of ionospheric Total Electric Content (TEC), phase scintillation and Rate of TEC Index (ROTI) were analyzed during the 26 August 2018 geomagnetic storm period. Results show that the TEC anomalies reach 20TECU on global scale and 6TECU over Canadian regions, respectively. The occurrence of phase scintillations is about 12.6% during the selected stormy day, which is only around 1% during geomagnetic quiet period. The occurrence of ROTI exhibits high correlation with that of phase scintillations during stormy geomagnetic conditions. The impact of ionospheric scintillations on positioning performance was analyzed by means of GPS Precise Point Positioning (PPP). It is proved that the 3D positioning root mean square errors are within 0.4 m for all test stations during the quiet geomagnetic condition. When it comes to the high geomagnetic condition, the magnitude of positioning errors significantly increase, which reaches 0.9 and 1.7m in horizontal and vertical directions, respectively.
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    Optimization of Kalman Filtering in Estimating Ionospheric Delay
    XUE Weifeng, NI Yude
    2021, 41 (2):  273-278.  doi: 10.11728/cjss2021.02.273
    Abstract ( 80 )   PDF (1415KB) ( 39 )   Save
    IFB (Inter-Frequency Bias) is the difference between the hardware delays of two frequencies in the GPS (Global Positioning System) satellite transmitter and the user receiver. It is also called the Instrumental Bias, which will introduce errors into the solution of the ionospheric delay. The current method of eliminating the IFB from the ionospheric delay is to establish a vertical ionospheric model based on GPS dual-frequency observation data and estimate the ionospheric model coefficients and IFBs in real time using Kalman filtering. However, the measurement noise covariance matrix in the filtering process does not consider the correlation between the system observations, which leads to inaccurate filtering models. Finally, it will affect the accuracy of the solved ionospheric delay. In this paper, the GPS dual-frequency observation data of 19 reference stations in the United States are selected, and the ionospheric model coefficients and the IFBs are estimated in real time by Kalman filter. In the filtering process, the estimation noise variance matrix is optimized by introducing the estimated variance of a priori IFB into the measurement noise variance. The calculation results show that the IFBs of satellites after optimization is closer to the related IFB of CODE (the Center for Orbit Determination in Europe). Substituting ionospheric delay after optimization into pseudo-range resolution, the standard deviation of the position error obtained by substituting the pseudo-range solution decreases by 12.5% and 15.4% respectively in the eastward direction and the zenith direction. The average error in the zenith direction decreased by 17.6%, thus the positioning accuracy was improved.
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    Structures and Interannual Variations of the Nocturnal Mesospheric Na and Fe Layers at 30°Normalsize
    HU Yunjie, YI Fan
    2021, 41 (2):  279-285.  doi: 10.11728/cjss2021.02.279
    Abstract ( 78 )   PDF (2092KB) ( 25 )   Save
    By analyzing the observational data of the Wuhan University Na and Fe lidars from January 2004 to December 2011, the average characteristics, nighttime and seasonal variations of the mesospheric Na and Fe layers at 30°N are obtained. The average centroid height of the Na layer is 91.36km, while the average RMS (root-mean-square) width is 4.64km. The corresponding results for the Fe layer are respectively 88.99 and 4.57km. Considering the influence of the nighttime and seasonal changes of the Na and Fe layers, we extract the interannual changes of the Na and Fe layers. It is found that both the Na and Fe layers are relatively stable during this period. The centroid height of the Na layer decreases by about 58m in the nearly eight years with an annual change rate of -7.91m, and the RMS width of Na layer decreases by about 151m with an change rate of -20.60m·a-1. Meanwhile the centroid height of the Fe layer has a decrease of about 230m with an annual change rate of -31.36m·a-1, and the RMS width of the Fe layer show an increases with an annual change rate of 21.01m·a-1. In addition, the factors that affect the interannual variation of the metal layer were analyzed, and the similarities and differences between the Na layer and the Fe layer were drawn. Based on our research, it is estimated that the atmospheric temperature in the MLT region over Wuhan has a cooling trend closed to pre decade 0.85K.
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    Space Life Science and Microgravity Science
    Research Progress of Space Microbial Experimental Technologiesormalsize
    YUAN Junxia, YIN Hong, MA Lingling, ZHANG Wende, ZHANG Qin, XU Kanyan
    2021, 41 (2):  286-292.  doi: 10.11728/cjss2021.02.286
    Abstract ( 69 )   PDF (3072KB) ( 34 )   Save
    Microorganism is often used as biological model for space life research, extraterrestrial life detection and research on planetary protection due to its simple structure, short growth cycle, fast propagation and easy space loading. With the development of China's space station program, the demand for more advanced microbial space experimental device is becoming more and more urgent. In this study, the microbial techniques which have already been implemented in space environment were investigated, and the progress and trend of space microbial experimental techniques including microbial incubation, preservation, detection, analysis, as well as extraterrestrial life detection were also discussed. Finally, suggestions on the development of space microorganism experiments using China's Space Station in the future are put forward in this paper.
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    Effects of 180-day's Isolation on Bone, Glycolipid Metabolism and Their Correlation Analysis
    YANG Chao, XU Zihan, LI Kai, ZHANG Hongyu, WANG Hailong, WU Feng, XU Zi, DAI Zhongquan, LI Yinghui
    2021, 41 (2):  293-300.  doi: 10.11728/cjss2021.02.293
    Abstract ( 52 )   PDF (2168KB) ( 23 )   Save
    During the long-term space flight, the astronauts are in the confined weightlessness environment. However, the impact of confined environment on bone metabolism and glucose and lipid metabolism is not elucidated. In this paper, the changes of bone metabolism, glucose and lipid metabolism and their correlations through Space 180 CELSS System test of four volunteers were analyzed. Results showed that confined environment affected bone formation indices (BGP, PICP, BAP). Serum insulin level changed significantly during the test, and Lipid metabolism indicators have a downward trend. Correlation analysis showed that BGP was positively correlated with FRUC (r=0.525, p=0.001). There was also a significant positive correlation between BGP, CHOL and LDL (r=0.376, p=0.024; r=0.391, p=0.018). The results showed that the metabolism of bone and glycolipid was changed obviously in this experiment, and there was mutual regulation between them.
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    Combustion Chamber Design and Analysis of the Space Station Combustion Science Experimental Systemormalsize
    ZHANG Xiaowu, ZHENG Huilong, WANG Kun, YANG Xiaofang
    2021, 41 (2):  301-309.  doi: 10.11728/cjss2021.02.301
    Abstract ( 97 )   PDF (7634KB) ( 31 )   Save
    The Chinese Space Station Combustion Science Experiment System is capable of conducting microgravity combustion experiments of multiple fuel types in orbit. The combustion chamber, one of the key components, is a pressure vessel that can be sealed. It is equipped with interfaces for the experiment inserts such as mechanical, oxidizer, exhaust gas emission, power supply, control and cooling. In this paper, the detailed design and analysis of the combustion chamber is based on the technical indicators such as pressure-bearing range, leakage rate, and transmitted light band. The combustion chamber adopts a sectional structure, which consists of a hinged door assembly, a locking ring assembly, a connecting ring assembly, a cylinder assembly, etc. Seals are used at the connection positions. The strength, stiffness and random vibration response of the combustion chamber structure were checked through pressure analysis, modal analysis and random response analysis. The results verified the safety and reliability of the combustion chamber design, which can meet launch and in-orbit operational requirements.
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    Space Exploration Technology
    Trajectory Design for Solar Approaching Detection Mission Using Multiple Resonant Gravity Assists of the Venus
    ZHANG Jiawen, ZHENG Jianhua, WANG Youliang, LI Mingtao
    2021, 41 (2):  310-319.  doi: 10.11728/cjss2021.02.310
    Abstract ( 73 )   PDF (2732KB) ( 48 )   Save
    To approach close to the Sun, direct launch from the Earth costs a lot of energy, which can be effectively reduced by the gravity assist of the Venus. In this paper, interplanetary transfer trajectories with multiple resonant gravity assists of the Venus are designed for a solar approaching detection mission. And design models for the trajectories with continuous resonant gravity assists, as well as resonant and non-resonant gravity assists combined are built. A mission launched between 2025 and 2028 is studied. The study shows that, compared with trajectory with continuous resonant gravity assists, trajectory with resonant and non-resonant gravity assists combined is useful for reducing transfer time of solar approaching detection mission. And its impact on the energy cost is not universal, which is related to the resonance ratio in the trajectory.
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    Location and Accuracy Validation of Lunar Landing Point Based on Multi-source Imagesormalsize
    WANG Jia, XIN Xin, WAN Wenhui, CUI Xiaofeng, RONG Zhifei, YOU Yi, HE Ximing
    2021, 41 (2):  320-328.  doi: 10.11728/cjss2021.02.320
    Abstract ( 80 )   PDF (5155KB) ( 38 )   Save
    High-precision positioning of the landing site is a critical step in the mission and an important prerequisite for surface operations of the lander and rover. In this paper, a high-precision positioning method of the landing site was designed based on image feature matching and multiple image localization methods. And the positioning experiment and accuracy validation were carried out in Chang'E-3 landing site. On the basis of high-precision image matching and geometric transformation, the matching precision between the sequent descent images reached sub-pixel, and the matching accuracy between LRO NAC image and medium-resolution descent image was better than 1 pixel. The landing position was calculated to be (44.1196°N, 19.5148°W). This method comprehensively utilized multi-source images, and didn't entirely depend on the mapping accuracy of the landing base map. It was a further refinement of the matching results between the images and landing base map. So, this high-precision positioning method can be applied in future deep space exploration missions.
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    Space-based Optical Target Determination Based on Gooding Algorithm
    YAN Ruidong, WANG Ronglan, GONG Jiancun, LIU Siqing, SHI Liqin, LUO Bingxian, WANG Hong
    2021, 41 (2):  329-336.  doi: 10.11728/cjss2021.02.329
    Abstract ( 85 )   PDF (1320KB) ( 21 )   Save
    In this paper, optical target monitoring orbit determination using the Gooding algorithm based on the 400km altitude space platform was researched. The measurement error was set to 3" and 6" respectively for 800km, 1500km altitude low Earth orbits and 36000km altitude geosynchronous orbit to determine the initial orbit and precise orbit. Simulation results show that the initial orbit determination accuracy of the 4~15min arc is about 10km, and the 1~2min arc is about 100km when the measurement data error is between 3" and 6". The error of 15min initial determination arc is 100m. As the arc is less than 10min, the improved error accuracy of the orbit is in the order of km scale. As the measurement data error is 3", the initial orbit determination accuracy of the 15~20min arc is about tens of kilometers, and that of the 8~10min arc is 100km. The improved orbit has an error of km. When the measurement data error is 6", the accuracy of the initial orbit determination of the 20min arc is at the magnitude of 10km, the accuracy of the initial orbit determination of the 8~15min arc is at the magnitude of 100km, and the error accuracy of the improved orbit is at the magnitude of 10km.
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    Application of Precision Thermal Control Techniques in Taiji-1 satelliteormalsize
    LIU Hong, ZHANG Xiaofeng, FENG Jianchao, ZHU Cheng, CAI Zhiming, XU Yu
    2021, 41 (2):  337-341.  doi: 10.11728/cjss2021.02.337
    Abstract ( 80 )   PDF (2613KB) ( 43 )   Save
    In order to detect gravitational waves in space, the Chinese Academy of Sciences has drawn up the Taiji plan. The first step of the Taiji plan is to verify the key techniques of the core payload through the Taiji-1 satellite in low Earth orbit. Because the temperature stability directly affects the measurement accuracy of the interferometer ranging and acceleration, the temperature control index of (T±0.1) K with high precision and high stability is proposed for the Taiji-1 satellite. Based on this requirement, an efficient thermal control scheme was designed. In the scheme, the thermal control from the selection of thermal components to the application of stand-alone equipment was controlled according to high indicators. At the same time, in the process of thermal implementation, in order to ensure the efficiency of the scheme, detailed control was also carried out. The thermal control scheme adopts the “constant temperature cage” as the design concept, adopts the means of three-stage temperature control, and combines the principle of active and passive. Finally, the high stability index of on-orbit flight temperature control of (T±0.005) K is obtained. Through the application research of high precision and high stability technology, it is found that thermal control heating scheme, heat leakage control, single resolution of temperature controller, temperature measuring circuit, control algorithm, control precision, temperature measuring resolution of temperature measuring element are still the important factors that restrict high precision temperature control technology.
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    Design of Ground Test System for Chang'E-4 Lander Load Electric Control Box
    CUI Tianshu, AN Junshe, WU Qi
    2021, 41 (2):  342-347.  doi: 10.11728/cjss2021.02.342
    Abstract ( 96 )   PDF (929KB) ( 38 )   Save
    The ground comprehensive test of spacecraft electronic equipment is an important part in the development of spacecraft. It plays an important role in equipment function verification and performance evaluation. The ground test system of the Chang'E-4 lander load electric control box adopts modular, reusable design and CPU+FPGA single-machine integrated architecture. It can provide power supply test, 1553B communication bus simulation test, indirect command test, asynchronous serial communication test, real-time data processing and other functions in one integrated system, is suitable for spacecraft electronic equipment single machine debugging, configuration test and environmental simulation test and other types of test requirements. The test of each interface, function and performance of the load electric control box indicates that the system meets the test requirements of stand-alone debugging, status confirmation and troubleshooting of the spaceborne equipment, which strongly supports the successful on-orbit operation of the Chang'E-4 lander load electric control box.
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