2011 Vol. 31, No. 4

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MHD simulations on the interaction of the solar wind with the magnetosphere
Wang Chi
2011, 31(4): 413-428. doi: 10.11728/cjss2011.04.413
Abstract(3583) PDF 1246KB(1500)
Abstract:
The magnetosphere is outermost layer of the geospace. Interaction of the solar wind with the magnetosphere is one of the key links among the space weather chain process from the Sun to Earth, thus becomes one of the key issues in space weather study. The characteristics of the geospace, including time-dependent, multiple components, and non-linearity, make the traditional analytic study very difficult. Numerical simulations as new means to investigate the coupling system, has played an important role in recent decades. The global MHD simulation about the magnetosphere started in 1970s, and limited to 2D initially. Since the intrinsic 3D characters of the magnetosphere, 3D MHD simulations thrived in 1980s. This paper briefly illustrates the characteristics of the 3D global magnetosphere MHD simulations, and their current status. The framework of the 3D global MHD magnetosphere simulation, and its application to the interaction of interplanetary shocks with the magnetosphere, large-scale current systems, reconnection voltage and cross polar potential drop, K-H instability in the magnetopause etc. are presented.
Numerical study about the nonlinear instability of the Sweet-Parker thin current sheet with shearing flows
Ni Lei, Yang Zhiliang
2011, 31(4): 429-435. doi: 10.11728/cjss2011.04.429
Abstract(2908) PDF 589KB(1298)
Abstract:
In this paper, numerical simulation results of nonlinear Plasmoid instabilities are presented. A two dimensional incompressible MHD code is used to calculate the results. The adaptive mesh refinement and MPI techniques are enable in this code. Harris sheets are used as the initial equilibrium conditions and small perturbations of the current density are applied to make the system unstable. Sequences of plasmoid instability processses for different Lundquist numbers have been studied. The Harris sheets will always evolve in to thinner Sweet-In this paper, numerical simulation results of nonlinear Plasmoid instabilities are presented. A two dimensional incompressible MHD code is used to calculate the results. The adaptive mesh refinement and MPI techniques are enable in this code. Harris sheets are used as the initial equilibrium conditions and small perturbations of the current density are applied to make the system unstable. Sequences of plasmoid instability processses for different Lundquist numbers have been studied. The Harris sheets will always evolve in to thinner Sweet-Parker current sheets with shearing flows in the early stage. As the Lundquist number S ≥ 105, the Sweet-Parker thin current sheets are unstable and secondary islands appear. The critical aspect ratio for the unstable Sweet-Parker thin current sheet is around 65. The larger the Lundquist number is, the thinner the Sweet-Parker sheet, and the more secondary islands appear. These secondary islands are ejected out along the current sheet, grow bigger with time and coalesce with each other in the later stage. The reconnection rate of the current sheet has been increased a lot due to secondary instabilities. The peak reconnection rates in each reconnection processes for different Lundquist number are picked about to study the relationship between the Lundquist number and the reconnection rate, which has been found no longer scales with Lundquist number as S- 1/2, but weakly depends on S.
SPE short-term forecast with the photospheric magnetic field properties and traditional forecast factors
Cui Yanmei, Li Rong, Liu Siqing
2011, 31(4): 436-440. doi: 10.11728/cjss2011.04.436
Abstract(3092) PDF 463KB(1182)
Abstract:
In Ref.[1] a simple Solar Proton Events (SPE) short-term forecast model is built with three solar photospheric magnetic physical properties (the maximum horizontal gradient of longitudinal magnetic field |▽hBz |m, the length of neutral line with strong gradients L, and the number of singular points η), which suggested magnetic physical properties are effective in forecasting SPE. The traditional SPE forecasting models, which have not used magnetic physical properties as input parameters, often have low Probably of Detections (POD) or high False Alarm Rates (FAR) for SPE. This paper built a more effective SPE short-term forecasting model with the traditional SPE forecasting parameters and magnetic physical properties by BP neural network. Model A uses only the traditional SPE forecasting parameters and Model B uses the traditional SPE forecasting parameters as well as those three magnetic physical parameters. In testing 973 samples during 2002--2003, Model A and B have the same POD while Model B has a lower FAR than Model A. It further testified that magnetic physical properties are effective for forecasting SPE. And the most important thing is that it will largely improve our practical ability in forecasting SPE.
Study on external field of magnetic quiet periods over Chinese mainland
Feng Yan, An Zhenchang, Sun Han, Mao Fei
2011, 31(4): 441-452. doi: 10.11728/cjss2011.04.441
Abstract(3566) PDF 1205KB(926)
Abstract:
The fourth generation comprehensive model of magnetic field CM4 was reasonably used in this paper to study the variation of external field in magnetic quiet periods over Chinese mainland during 1960--2000. The distribution and variation of ionospheric field and magnetospheric field separated from the external field in 1960--1970, 1970--1980, 1980--1990 and 1990--2000 were also calculated and analyzed. Results showed that X component of external field variation was increased firstly, then decreased with time. The change was about 32 nT. The variation of corresponding magnetospheric field was increased firstly, then decreased continuously. The change was about 23.7 nT. The Y Component of external field variation was decreased, increased and decreased with time. The change was about 3.8 nT. The variation of corresponding magnetospheric field was generally decreased and then increased with time. The change was about 2.3 nT. The Z Component of external field variation was decreased and then increased with time. The change was about 4.6 nT. The variation of corresponding magnetospheric field was decreased then increased. The change was about 9.3 nT. The intensities of corresponding ionospheric field to the three components were all less than 1 nT during 1960--1970, 1970--1980, 1980--1990 and 1990--2000. They vary with interesting phenomenon between positive and negative values, which maybe have something to do with 11 years' solar activities.
Technique of reconstructing ionospheric TEC map with the data of single station based on the background field by using IRI
Weng LIbin, Fang Hanxian, Yang Shenggao, Wang Sicheng
2011, 31(4): 453-458. doi: 10.11728/cjss2011.04.453
Abstract(3201) PDF 623KB(1350)
Abstract:
Owing to the sparse data, the reconstructing ionospheric maps are not accurate enough by using the interpolation methods directly, especially in the verges. In order to obtain better TEC maps, the reconstruction was performed by Inverse Distance Weighting and Kriging Methods with IRI-2007 used as the background field. The test produced a better performance according to using Cross-validation method. As a result, the new technique decreased the errors effectively, especially in the verges, and the proportions of absolute errors between -0.25~0.25 TECU at all grid points in the reconstructing ionospheric map were improved by 70\% and 100\%. Meanwhile statistic errors showed a normal distribution. The reconstructed precision can be improved by using more exact background or successive correction method.
Atmospheric density calibration using the real-time satellite observation
Miao Juan, Liu Siqing, Li Zhitao, Qin Guotai, Tang Geshi
2011, 31(4): 459-466. doi: 10.11728/cjss2011.04.459
Abstract(2746) PDF 708KB(1187)
Abstract:
For low Earth satellites, thermospheric density models are widely used in orbit determination and prediction. However, typical models often show density errors of 15 %~30 % under normal condition and the errors may be much greater during unusually solar and geomagnetic period. Density errors can be translated into orbit errors and effect mission plan, re-entry operations and precise orbit determination. In this paper, on the basis of detected data of Shenzhou, a kind of model calibration is expected to be developed on real-time detected data. By analyzing and comparing the character of density error for the national atmosphere model NRLMSISE-00, a kind of average calibration method is developed for relative quiet geomagnetic field (Ap≤30). During the quiet geomagnetic field, the errors of model at the same local time and latitude are considered approximately identical, so the error may be substituted by average error at the same station. The results of model are tested based on Shenzhou 4 data by two means and both are improved in accuracy. The errors of 20 % decreased to 6 % by real-time error calibration. The errors of one day in advance decreased to 7.8 %, two days in advance decreased to 9.4 % and three days in advance decreased to 10.5 %.
Cylindrical gravity waves generated by thunderstorm driven sources at tropospheric altitudes
Yu Yonghui, Liu Yinfeng
2011, 31(4): 467-473. doi: 10.11728/cjss2011.04.467
Abstract(2626) PDF 684KB(843)
Abstract:
Solid evidences have shown tropospheric thunderstorms as representative sources of gravity wave activity at mesospheric altitudes. For instances, mesospheric heating was detected by rockets above thunderstorms. Upward traveling gravity waves were also observed by radar at stratospheric altitudes. Coherent circular gravity wave structure through nightglow emission exhibits from ground and satellite based platform observations. All these evidences are strongly associated with underlying thunderstorm activity. These types of storm occur frequently over the eastern coast of China, and over many other coast lines of the globe. Their mesospheric effects have not yet been adequately studied and described in scientific literature. With a numerical modeling, the paper focuses on a better understanding of the basic physics underlying the generation of such gravity waves and their energy dissipation at mesospheric altitudes. It shows that, during thunderstorm formation the cumulus can intensely and periodically absorb and release energy within large area, the instability of the troposphere occurs along with this periodical convection. Under such conditions, a simulated packet of the cylindrical gravity waves arises and propagates upward in our numerical model.
Numerical analysis of meteor parameters and height distribution of Meteor
Zhang Yabin, Xu Bin, Xue Kun, Zhao Lei, Chen Jinsong
2011, 31(4): 474-481. doi: 10.11728/cjss2011.04.474
Abstract(2577) PDF 728KB(1274)
Abstract:
Based on the meteor radar, one can study the radiant distribution and the time variant of meteors, forecast the passage time of meteor showers, and also investigate space, and so on. Based on standard theory, the effects of main factors, such as ambipolar diffusion, the initial trail radius, the finite meteor velocity and the Pulse Repetition Frequency (PRF), on the radar echoes power at different radar frequencies and meteor velocities have been numerical analysis and calculated. The observation data of meteor decay time and the ambipolar diffusion coefficient are consistent with the theories. By analyzing the 571632 meteors observed by Kunming meteor radar, the height distribution of meteors model has been constructed, the result predicted by this model agrees with observation data at different months.
Research of lunar tectonic features: Primary results from Chang'E-1 lunar CCD image
Wang Jie, Zeng Zuoxun, Yue Zongyu, Hu Ye
2011, 31(4): 482-491. doi: 10.11728/cjss2011.04.482
Abstract(3176) PDF 1208KB(1718)
Abstract:
The Moon retains the information of initial period, because its geological activity was ceased 3.1billion years ago. This information is very important for us to recognize the formation and evolution of the Moon, the earth and even the solar system. On the basis of initial study and Chang'E-1 CCD images, the geological, topographic and geomorphologic features of the main tectonic patterns on the Moon are introduced. The two important kinds of structures on the moon are circular tectonics and linear tectonics. Circular tectonics are the annular appearances on remote sensing images displayed through architecture and color, which are the most striking features of lunar images. This article studies the formation of Mons Rümker, Hainzel Crater, King Crater and the fracture at the bottom of Humboldt Crater, and then, analyzes the difference in lunar crater both near and far side, the South and North Pole. Linear tectonics refer to those structures extended as linear on lunar surface, which can reflect the global or territorial stress condition and stress field of the lithosphere and tectonic forms on the planets. This article also studies the echelon structure nearby the Cauchy Crater, step scarp of Mare Humorum, regional fault nearby the Hippocrateson Crater, fault structures along Apennine Mountains, crater chain at the bottom of Davy Crater, Rima Hyginus and Vallis Alpes. The result shows that the Chang'E-1 CCD images have sharp details and rich information which are clear enough to research the lunar tectonic features.
Meteorological rocket sonde of meridian project and its detection results
Shi Dongbo, Wei Feng, Zhang Yu, Wang Lianzhong, Jiang Xiujie, Liu Bo
2011, 31(4): 492-497. doi: 10.11728/cjss2011.04.492
Abstract(2892) PDF 600KB(1162)
Abstract:
A meteorological rocket sonde based on GPS system is developed, which is composed of a microminiature bead form thermistor temperature sensor with rapid response and negative temperature coefficient, a piezoresistive silicon pressure transducer and a GPS-Receiver. Compared with meteorological rocket sondes flight before, this new sonde can make higher accuracy measurement of meteorological parameters on temperature, pressure, density and wind field, and its telemetry receiving equipment is more portable. Besides, simple prelaunch preparation work and high system reliability are two other advantages of it. The launching test of the sonde has been successfully conducted in the Meridian Project, and satisfactory detection results have been obtained.
Assessing single-event-upsets in SRAM based on TCAD and Geant 4
Chen Shanqiang, Shi Liqin
2011, 31(4): 498-502. doi: 10.11728/cjss2011.04.498
Abstract(3074) PDF 467KB(1129)
Abstract:
A new method based on Geant4 and Technology Computer Aided Design (TCAD) is described to assess Single Event Upsets (SEU) sensitivity of SRAMs (Static RAM) in the design phase. SRAM's response to radiation and Heavy ion induced upsets was obtained by TCAD simulation instead of ground simulation experiments. Heavy-ion simulation data are fitted by Weibull Function. Then, the energy deposition of secondary particles produced by proton-silicon nuclear reaction was calculated using Geant4 which is based on Monte Carlo method. Finally, the proton-induced upsets can be achieved by combining with Weibull Function. Using this method, the heavy ion and proton-induced SEU rates in TSMC 0.18 μm SRAM were calculated, and the results are basically consistent with ground simulation experiments.
Research of combined effect of small space debris and atomic oxygen
Li Hongwei, Cai Minghui, Han Jianwei, Huang Jianguo, Li Xiaoyin, Yu Jinxiang, Gao Zhuxiu, Liu Danqiu
2011, 31(4): 503-508. doi: 10.11728/cjss2011.04.503
Abstract(2793) PDF 787KB(1179)
Abstract:
Using plasma drag particulate accelerator and atomic oxygen device based on PIG ion source, the first experiment was carried out about the combined effect of small debris and atomic oxygen on both the standard Kapton and Kapton with aluminum film. The result indicates that hypervelocity impact by particulate can accelerate the erosion effect of atomic oxygen on both Kapton and Kapton with aluminum film. The combined effect of hypervelocity impact and atomic oxygen is more important on Kapton with aluminum film than Kapton without film. This is because the impact by hypervelocity particles can destroy the aluminum film which prevents the atomic oxygen from eroding Kapton. So when consider the atomic oxygen effect on Kapton with aluminum film, the combined effect of hypervelocity impact by space debris and atomic oxygen should not be neglected. As a result, this effect is a threat to the life-span and credibility of spacecraft, which will restrict the development of high credibility and long life spacecraft.
Surface charging simulation of LEO spacecraft
Yang Fang, Shi Liqin, Liu Siqing, Gong Jiancun
2011, 31(4): 509-513. doi: 10.11728/cjss2011.04.509
Abstract(2946) PDF 531KB(1254)
Abstract:
The subject of this paper is to investigate surface charging simulation of LEO spacecraft. SPIS was applied to simulate the surface charging of spacecraft in LEO plasma environment. A simple satellite model was made in SPIS with several material assigned as satellite surfaces. This was done with the assumption that solar irradiation is far less than the environment plasma and secondary electron was considered. Result of the numerical simulation has been laid out and compared with the charging theory and in situ observation. It is concluded that charging result can reflect the difference of distinct material, especially the difference between conducting material and non-conducting material. Equilibrium potential and charged time agree with the estimation based on plasma sheath theory and has a good relevance with observation. Simulation result can also provide wake flow structure of moving spacecraft which is hard to obtain analytic solution. Finally, character of LEO spacecraft surface charging simulation made by SPIS has been concluded and is considered as a reasonable result.
Study on extinction performance of IR interference materials exposed to atomic oxygen
Liu Guosheng, Guan Hua, Lü Huiping
2011, 31(4): 514-519. doi: 10.11728/cjss2011.04.514
Abstract(2342) PDF 561KB(1150)
Abstract:
Brass and graphite particles are effective Infrared Ray (IR) interference materials which were usually used in conventional passive jamming technology, but Atomic Oxygen (AO) may corrode them and weaken their performance if they were used in outer-space. For analyzing the effect of AO to IR interference materials and exploring whether the IR interference materials can be used in outer-space, an experiment was conducted to investigate the AO effects. The mass, X-ray diffraction and IR transmittance of the sample were characterized. Results showed that the mass of brass increased 0.004 mg•cm-2 and the mass of graphite particles lost 0.117 mg•cm-2 when the cumulative flux of AO reached 5.0×1019cm-2. The mass extinction coefficients of IR band of 3~5μm and 8~12μm changed from 3.64 m2•g-1 and 2.74 m2•g-1 before AO exposure to 3.14 m2•g-1 and 2.65 m2•g-1 after AO exposure, the extinction capability of brass to IR was weakened. The mass extinction coefficients of IR band of 3~5μm and 8~12μm changed from 6.54 m2•g-1 and 5.78 m2•g-1 before AO exposure to 2.38 m2•g-1 and 2.27 m2•g-1 after AO exposure, the extinction capability of graphite particles to IR was weakened obviously.
Collision prediction analysis using refined error data
Yang Xu, Liu Jing, Wang Ronglan, Yu Youcheng
2011, 31(4): 520-526. doi: 10.11728/cjss2011.04.520
Abstract(2748) PDF 576KB(1077)
Abstract:
With the expansion of human's activity in the outer space, the population of the space debris has grown greatly. Several collisions and breakup events in the recent period increased the total number of space debris sharply. These debris are causing serious threat to orbital spacecraft, and efficient protection must be done to deal with the growing collision risk. Space debris collision avoidance job mainly aims at big space debris that can be monitored, and predicting the collision risk between spacecraft and space debris and then evaluating the risk through certain collision criterion. So a reasonable orbit maneuver decision can be made to perform any necessary mitigate action to avoid possible collisions. Collision probability is the primary index to evaluate collision risk. The combined object size, the minimum distance and errors are main factors affecting collision probability. When the combined object size and the minimum distances are not different significantly, error data will be the crucial factor affecting collision probability. This paper brings forward a method of using refined error data to compute collision probability on the basis of whole day errors. And this method makes improvement in analyzing possible collisions.
Measure for relative position and pose of RVD spacecrafts based on trinocular vision method
Yao Rongbin, Ding Shangwen, Li Shengquan, Fan Bing, Li Qiang
2011, 31(4): 527-533. doi: 10.11728/cjss2011.04.527
Abstract(3024) PDF 592KB(1040)
Abstract:
With the continuous development of Manned spaceflight and space station, autonomous spacecraft Rendezvous and Docking Technique becomes more important. During the spacecraft's final approach phase of Rendezvous and Docking (RVD), real-time accurate measurement of the relative position and orientation parameters between the two spacecrafts is the key to success. For Rendezvous and Docking spacecrafts position and orientation parameters of the process of measurement problems, a trinocular measurement method was used. This paper not only prescribed the measuring principle of trinocular, but also established a non-linear mathematical model based on trinocular vision. To solve relative position and pose of RVD spacecrafts based on trinocular vision method, the non-linear mathematical model was transferred into a non-linear optimization problem; and was completed by Levenberg-Marquardt algorithm. Experiments with simulated data show that compared with linear methods of binocular vision and trinocular, this non-linear trinocular method can reduce the impact on the image matching error, meanwhile improve the located positioning accuracy of feature points and increase the reliability of measurement system.
Research on autonomous navigation algorithm of deep space based on Line-of Sight vector
Zhu Shengying, Chang Xiaohua, Cui Hutao, Cui Pingyuan
2011, 31(4): 534-540. doi: 10.11728/cjss2011.04.534
Abstract(2898) PDF 583KB(1486)
Abstract:
In this paper, an autonomous navigation algorithm is based on Line-of-Sight (LOS) vector in order to solve the orbit determination problem of deep space probe during the interplanetary phase. Considering the characters of the deep space mission, the Sun LOS vector and Earth LOS vector are served as the measurement of the navigation system. Following the measurement principle of the Sun senor, the corresponding measurement model and error expression of Sun LOS vector are derived. The measurement model of the pixel and line in the camera coordinates is given through the analysis of the navigation camera, and the measurement error of Earth LOS vector is deduced. The position vector and its error expression are derived in detail based on the geometric relation of the LOS vectors in the inertial space. Finally, the autonomous navigation algorithm is established utilizing extended Kalman filter, and is demonstrated by the practical data of Deep Impact mission.
Design and implementation of high reliability image data transmission unit on the space application
GUO Lin, JIANG Yuanyuan, CHEN Jianfei, CAO Song, LI Huijun, CHEN Xiaomin
2011, 31(4): 541-546. doi: 10.11728/cjss2011.04.541
Abstract(2677) PDF 752KB(1392)
Abstract:
SpaceWire is an onboard data-handling network for spacecraft which offers high-speed, low power, simplicity, low cost, and architectural flexibility. The unit uses SpaceWire protocol to implement high speed image data transmission for space application. The FPGA can control the system to realize initialization and handling of data packets transmission, interruption and error status. The reliability design approach of FPGA was elaborated on, including the design of state machine, asynchronous clock domains, data transmission and error recovery. The unit can be used successfully in the 140Mbit/s image data transmission. For the burst error of link, the unit can recover the error data in a certain period of time, which can guarantee the validity and stability of data transmission.

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