2016 Vol. 36, No. 3

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Overview of the Solar Polar Orbit Telescope Project for Space Weather Mission
XIONG Ming, LIU Ying, LIU Hao, LI Baoquan, ZHENG Jianhua, ZHANG Cheng, XIA Lidong, ZHANG Hongxin, RAO Wei, CHEN Changya, SUN Weiying, WU Xia, DENG Yuanyong, HE Han, JIANG Bo, WANG Yuming, WANG Chuanbing, SHEN Chenglong, ZHANG Haiying, ZHANG Shenyi, YANG Xuan, SANG Peng, WU Ji
2016, 36(3): 245-266. doi: 10.11728/cjss2016.03.245
Abstract(1658) PDF 4166KB(2580)
Abstract:
The Solar Polar ORbit Telescope (SPORT) project for space weather mission has been under intensive scientific and engineering background studies since it was incorporated into the Chinese Space Science Strategic Pioneer Project in 2011.SPORT is designed to carry a suite of remote-sensing and in-situ instruments to observe Coronal Mass Ejections (CMEs),energetic particles,solar high-latitude magnetism,and the fast solar wind from a polar orbit around the Sun. The first extended view of the polar regions of the Sun and the ecliptic enabled by SPORT will provide a unique opportunity to study CME propagation through the inner heliosphere,and the solar high-latitude magnetism giving rise to eruptions and the fast solar wind.Coordinated observations between SPORT and other spaceborne/ground-based facilities within the International Living With a Star (ILWS) framework can significantly enhance scientific output.SPORT is now competing for official selection and implementation during China's 13th Five-Year Plan period of 2016-2020.
Dependence of the Intensity of Solar Energetic Particle Event on the Twin-CME:Two Cases Study
CHEN Minhao, CHEN Yulin, LE Guiming, LU Yangping, LI Zhongyi, YIN Zhiqiang
2016, 36(3): 267-271. doi: 10.11728/cjss2016.03.267
Abstract(1888) PDF 715KB(906)
Abstract:
Solar energetic particle events often associate with solar flare and Coronal Mass Ejection (CME).Because the interaction of twin-CME is the key factor of solar energetic particle events,by using the SOHO satellite observations of energetic particle strength,flare intensity and relative height and time of CMEs,and through the speed of height fitting,the relationship between the intensity of Solar Energetic Particle events (SEP) and the associated twin-CME is investigated.The two SEP occurred on 15 April 2001 and 20 January 2005 respectively.The results show that the intensities of the two SEP have no relationship with the associated twin-CME.The protons of E ≥ 10 MeV are only associated with the concurrent solar flare and CME.
Influence of the Dipole Tilt Angle on the Subsolar Standoff Distance and the Tail Flaring Angle of the Bow Shock
YUAN Huanzhi, LÜ Jianyong, WANG Ming
2016, 36(3): 272-278. doi: 10.11728/cjss2016.03.272
Abstract(1674) PDF 1643KB(930)
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The Earth's bow shock has been found to be affected by the dipole tilt angle.Based on the bow shock crossings of IMP 8,Geotail,Magion 4,and Cluster 1,quantitative analysis has been made to examine the influence of the dipole tilt angle on the subsolar standoff distance and the tail flaring angle of the bow shock by fitting the bow shock shape and location in each range of the data sets after normalizing and classifying the data sets.The results show that the subsolar standoff distance increases as the absolute value of the dipole tilt angle increases,and the negative dipole tilt angle does greater influence on the standoff distance than the positive tilt angle;the flaring angle decreases with the increasing absolute value of the dipole tilt angle;when the dipole tilt angle changes from negative to positive,the bow shock moves to Earth,meanwhile the flaring angle increases.This study make a good foundation for the bow shock model which will include the effects of the dipole tilt angle.
A Method to Retrieve Magnetic Reconnection Locations on the Magnetopause Based on Energy-dispersion Characteristic
ZHU Changbo, ZHANG Hui, GE Yasong, PU Zuyin, LIU Wenlong, WAN Weixing, LIU Libo, CHEN Yiding, LE Huijun, WANG Yongfu
2016, 36(3): 279-286. doi: 10.11728/cjss2016.03.279
Abstract(1327) PDF 2331KB(792)
Abstract:
Magnetic reconnection on the magnetopause is a main way of energy transport from solar wind to magnetosphere.How magnetic reconnection is initiated is a hot yet unsolved topic in space physics research.However,on the magnetopause,it is difficult for a satellite to cross a site where reconnection is going on,and thus it is difficult to reveal the conditions which trigger magnetic reconnection.In this paper,a method is established to retrieve the locations of reconnection sites by using observations from THEMIS satellite.When reconnection initiates,the energy dispersion properties of ions ejected from the reconnection site can be observed by the satellite from a distance and are used to calculate the distance.The location of reconnection is then retrieved by tracing along modeled field lines for that distance.Our method is compared with other methods,and analyses indicate that our method may have higher accuracy than the others.
Longitudinal Variations of Total Ion Density in the Topside Ionosphere
YAN Fengchan, REN Zhipeng, WAN Weixing, LIU Libo, LONG Zhiyong
2016, 36(3): 287-296. doi: 10.11728/cjss2016.03.287
Abstract(1524) PDF 9191KB(655)
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Based on DMSP F13 Satellite observations from 1996 to 2005,the seasonal,geomagnetic latitude and solar cycle variations of the total ion density in the sunset topside ionosphere at middle and low latitudes are investigated.Results indicate that the longitudinal variation of the total ion density is obviously different between the low latitudes and the middle latitudes.Annual components of longitude structures seasonal variations are dominated at most latitudes,and these longitudinal structures show latitudinal dependence:relative strength of mid-latitude wavenumber-one structure in the southern hemisphere are much greater than that in the northern hemisphere;the hemispheric asymmetry of wavenumber-two structure is remarkable at middle and low latitudes;wavenumberthree structure and wavenumber-four structure are both much more dominant in the low latitudes than in the middle latitudes.Besides,contributions of different wave structures to total ion density are also examined:wavenumber-one structure is dominant at southern middle latitudes,and in the northern winter,the region around 15°N is mainly controlled by wavenumber-two structure. Wavenumber-three structure and wavenumber-four structure only prevail at low latitudes.Contributions of different wave structures change with solar cycle variations.
Correction Accuracy Evaluation and Analysis for GNSS Ionosphere Model
LIU Shuai, JIA Xiaolin
2016, 36(3): 297-304. doi: 10.11728/cjss2016.03.297
Abstract(2216) PDF 2147KB(1043)
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Ionospheric delay is one of the major error sources for navigation signal in its propagation path.Therefore,the understanding of the GNSS ionosphere model correction accuracy has a practical significance.In this paper,ionosphere correction models are introduced.With high precision global ionospheric maps as a benchmark and the ionospheric correction parameters in 2014,the correction accuracy of the three systems ionospheric delay is evaluation and analyzed.It is found that the correction rates of several current GNSS ionospheric correction model have reached about 65% to 75%.Through comparison of the second edition NeQuick model and the first edition NeQuick model which Galileo system used,it is found that there is no significant improvement in accuracy.GPS Klobuchar eight parameters model has a high precision at 25°-45°N in the northern hemisphere midlatitudes,but it has a poor distribution and lower accuracy in other regions of the world.However,NeQuick model global correction rate distributions are more even and smooth than those of the other models.
Study of Sporadic E Layers Based on Occultation Data Observed by FY-3C Satellite
YANG Jingjing, HUANG Jiang, XU Jie, DENG Baichang, QUAN Hongjun
2016, 36(3): 305-311. doi: 10.11728/cjss2016.03.305
Abstract(1612) PDF 6866KB(726)
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Using the GPS radio occultation data from June 2014 to May 2015 provided by FY-3C polar-orbiting satellites,the SNR disturbances of C/A code with sampling frequency of 50 Hz on a global scale are statistically analyzed,and the disturbance strength of sporadic E layers is also studied.Results show that the disturbance strength of sporadic E layer at mid-latitudes in the summer hemisphere area is far greater than that at the same latitudes in the winter hemisphere,and the disturbances of the sporadic E layers (Es) near the latitude of 40° are significantly enhanced.In addition,at 100 km height,the disturbances of Es layers reach the peaks at 10:00 LT and 22:00 LT. The occurrence rates of sporadic E in summer hemisphere are significantly higher than that in the winter hemisphere.The results observed by FY-3C satellite are consistent with those observed by the COSMIC system.Therefore,the occultation data of FY-3C satellite could be used to study ionospheric sporadic E layers.
Study of Refractivity Retrievals Based on GPS Radio Occultation Mean Bending Angles
SONG Yaxiong, FU Yang, HU Xiong, GONG Xiaoyan, YAN Wei, ZHAO Zengliang, DU Xiaoyong
2016, 36(3): 312-322. doi: 10.11728/cjss2016.03.312
Abstract(1174) PDF 5504KB(1410)
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The retrieval step from bending angle to refractivity requires background information.Retrieval schemes in different GNSS-RO processing centers use different types of background data, which is the source of inconsistency of the generated radio occultation climatologies In this paper, the COSMIC excess-phase data during Jan.,Apr.,Jul.and Oct.of 2008 was used to study the retrieving of monthly mean refractivity from monthly zonal mean bending angles The comparison results show that:it is not necessary to apply statistical optimization to individual bending angles, since the approach based on mean bending angles and the standard method produce nearly identical mean refractivity below 40 km;and above 50 km.The approach based on mean bending angles is better than the standard method when compared with mean refractivity generated from ECMWF data.
Atmospheric Density Model Calibration Using 2-dimension Kernel Regression Method
CHENG Guosheng, LI Xingxiang, LAI Peng, ZHOU Lü
2016, 36(3): 323-330. doi: 10.11728/cjss2016.03.323
Abstract(1694) PDF 3154KB(740)
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The errors of traditional empirical thermospheric density models often translate into orbit errors of the Low Earth Orbit (LEO) satellites,adversely affect applications such as re-entry operations,manoeuver planning,collision avoidance and precise orbit determination for geodetic missions.By using the data detected by Tiangong-1,the features of NRLMSISE-00 model's density errors is analyzed,and it is found that the errors of model at the similar local time and latitude can be considered approximately identical during the quiet geomagnetic field (Ap ≤ 30).In this paper, 2-dimension kernel regression method is used to estimate model's error based on the sample error data at the similar station.Finally,weighted calibration method is developed for the calibration of model's density according to the duration of time from the sample date to the prediction data,and the RMS level of the error could be reduced from 14.09% to 4.05% through calibration.The results indicate that thermosphere densities can be obtained in high precision with this method.
Calculation of the SEP Flux at 1 AU Orbit and Its Comparison with Multi-satellites Observations
WANG Yabing, ZHENG Yuqing, GU Bin, DING Liuguan, LE Guiming, LÜ Jianyong
2016, 36(3): 331-335. doi: 10.11728/cjss2016.03.331
Abstract(1456) PDF 921KB(1018)
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The SEP (Solar Energetic Particles) flux at 1 AU orbit is an important index of space weather condition.Based on the parameterized Green Function solution of the SEP transport equation in the ecliptic plane,the flux profile of the SEP event on 28 Sept.2012 at GOES,STEREO-A and STEREO-B positions on the 1 AU orbit is calculated,and results are compared with available observations.The results show that the flux peak Imax and its occurrence time tmax of the SEP profile are well consistent with the observation of GOES and STEREO-B.However,for STEREO-A, there is an evident difference between our calculation and the observation,which may be induced by the large angle distance between the site and the SEP source and the unknown solar activities on the backside of the Sun.The parameterized SEP flux formula may be applicable for single source impulsive SEP events.
Numerical Simulation of Thermal Storage Device of Foam Composite Phase Change Material in Microgravity
ZHANG Jingchi, SHENG Qiang, REN Weijia, TONG Tiefeng
2016, 36(3): 336-343. doi: 10.11728/cjss2016.03.336
Abstract(1478) PDF 2232KB(983)
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Phase Change Material (PCM) is particularly attractive due to its ability to provide high-energy storage density per unit mass in quasi-isothermal process.PCM Thermal Energy Storage (TES) device can effectively store thermal energy and maintain the temperature of electronic components in spacecraft.Two thermal energy storage devices filled with eicosane (C20) are presented.One is impregnated in carbon foams and the other is impregnated in copper foams.Numerical simulations of phase change process environment are performed by FLUENT software.The temperature distribution and solid-liquid phase interface changes are obtained.The results show that the temperature rising speed of heat source surface is reduced due to the high thermal conductive of Foam Composite Phase Change Material (FCPCM).FCPCM also could reduce the influence of gravity change on to thermal transfer.The results provide the scientific basis for the engineering application of FCPCM in microgravity.
Model Analysis for Predicting Aerodynamic Characteristics of Mars Entry
LÜ Junming, MIAO Wenbo, HUANG Fei, CHENG Xiaoli
2016, 36(3): 344-351. doi: 10.11728/cjss2016.03.344
Abstract(1244) PDF 2169KB(914)
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Martian atmosphere which is quite different from Earth atmosphere plays an important role for Mars entry vehicles.Therefore aerodynamic predictions for trajectory design and layout optimization should be settled firstly.Three-dimensional Navier-Stokes equations with real gas model and ideal gas model have been solved by a parallel code to analyze the impact of different models on aerodynamic characteristics,to obtain accurate,efficient and reliable model for aerodynamic predictions.The good agreement among the numerical results,the reference values and the flight data of Viking along the trajectory validates the real gas physical-chemical models and the numerical methods applied.Using real gas model and ideal gas model,aerodynamic characteristics of lift-entry Viking and zero angle of attack Mars Pathfinder have been predicted.The results show that predicts value of ideal gas model with effective specific heat ratio is very close to that of the real gas model, the deviation is about 1%,and the difference of the trim angle of attack is about 0.4°.Prediction of ideal gas with specific heat ratio from inflow temperature shows a large deviation.Real gas model and ideal gas model with effective specific heat ratio are suggested in aerodynamic characteristics predictions of Mars entry.
A New Ground-based Fabry-Perot Interferometer for Measurement of the Thermospheric Wind
WANG Houmao, WANG Yongmei, FU Jianguo, ZHANG Zhongmou
2016, 36(3): 352-357. doi: 10.11728/cjss2016.03.352
Abstract(1499) PDF 1029KB(1311)
Abstract:
As the thin air in the upper atmosphere (about 250 km),passive optical measurement is considered as the most efficient method for wind retrieval of the upper atmosphere.Because of high energy utilization and high spectral resolution,Fabry-Perot Interferometer (FPI) is one of the most widely used instruments for wind measurements.In this paper,a tiny ground-based FPI is designed by using a band-pass filter behind etalon and Galilean telescope system for wind observation of the upper atmosphere.The instrument is mainly composed of five parts including front optics sky-scanner,the etalon,Galilean telescope and filter,detector,and laser calibration system.The size of the instrument is 1.34 m×0.58 m×0.35 m,and the FPI is convenient to be transported from one place to another.Based on the instrument,several days of experiments are carried out at Langfang (39.40°N,116.65°E) station and Kelan (38.71°N,111.58°E) station for a detailed validation.The averaged wind deviation at Kelan sites between our FPI and American A-NCAR FPI is 11.8 m·s-1 when airglow is weak,which suggests good agreement between them.
Retrieval of Plume Density Profile by Microwave Interferometry
HE Lu, DONG Xiaolong, ZHANG Xiangkun
2016, 36(3): 358-365. doi: 10.11728/cjss2016.03.358
Abstract(1367) PDF 1481KB(946)
Abstract:
Microwave interferometer is an efficient tool for non-intrusively diagnosis of electron density of plasma,which can be used for the measurement of plume of helicon plasma thruster. Four different numerical Abel inversion algorithms,including the discretization method,the cubic spline interpolation method,the Hankel-Fourier transform method and the Nestor-Olsen method, are used to retrieved the plume density profile that is detected by microwave interferometry for the cases with and without noise.After analysis of the effect of sampling density on the retrieval error,the smoothing and interpolating solution is proposed to mitigate the under-sampling related problem.As a summary,the procedures of the retrieval and processing are proposed.Two principle verification experiments with microwave network analyzer have been done.In the first experiment,a circular pipe is measured as a axial symmetrical target,which simulates the plume,and the retrieval results match well with the shape of the pipe.In the second experiment,spatial resolved integrated phase shifts are retrieved by Abel algorithm.The radial electron density profile within the plume is calculated.The experiments and their results verify the performance and validity of both the system design and the retrieval algorithm.
Research of Spectrum Correction Method Based on All Phase FFT for Induction Magnetometer
REN Haiyan, ZENG Li, LIU Xu, WEI Dong, WANG Yan, CHEN Yu
2016, 36(3): 366-372. doi: 10.11728/cjss2016.03.366
Abstract(1335) PDF 1383KB(1806)
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Induction magnetometer,based on Faraday's law,is used to measure the magnetic field changes with low frequency in space.It usually has the function of on-orbit FFT spectrum analysis, which can obtain the information of magnetic field fluctuation directly,such as frequency and amplitude.However,when using FFT to process the truncated signal,non-complete period sampling will cause spectrum leakage and fence effect.Namely the spectrum information will generate deviations, which affects the accuracy of real-time monitoring of magnetic field changes.Compared with traditional FFT,the all-phase FFT with phase invariability can effectively prevent spectrum leakage.In this paper,an all-phase time-shift phase difference method (apFFT/apFFT) is used to correct the aveform data of a satellite induction magnetometer.Simulation and experimental results indicate that this method can improve the measurement accuracy.This study also provides a method about on-orbit spectrum analysis for the next generation of spaceborne induction magnetometer.
Study on Flexible Tether Critical Length at Equilibrium State
LI Aijun, LI Jingchen, WANG Changqing, DONG Zhe
2016, 36(3): 373-379. doi: 10.11728/cjss2016.03.373
Abstract(1460) PDF 724KB(1046)
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In order to determine flexible tether critical length at equilibrium,based on orbital motion of tether system,the tether equilibrium equations are established considering the atmospheric drag,tether extensibility and tether mass.Then,the load stress distribution is analyzed,and load equilibrium equations are established for determining the needed initial condition of tether equilibrium equations.Furthermore,the condition that tether length reaches critical value and the computing method of tether critical length are both given.Finally,different tether critical lengths are respectively calculated under three conditions including different load masses,tether diameters and load ballistic coefficients.Three different critical length equations are given by fitting.The impacts on critical length are analyzed under these three different conditions.
A Balanced Satellite Thermal Control Optimization Method for Different Orbit and Attitude
ZHOU Yangeng
2016, 36(3): 380-385. doi: 10.11728/cjss2016.03.380
Abstract(1552) PDF 1962KB(936)
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Based on analysis of the thermal control design of traditional satellites,an optimization method for satellite thermal design which is applicable to both Sun-synchronous orbit and lowinclination orbit is presented.Using this optimization method,thermal simulation analysis is made for a satellite under both orbit conditions,and the satellite thermal balance test and in-orbit validation are conducted for the Sun-synchronous orbit.Combined with thermal simulation results,it is shown that the thermal design of low-inclination orbit satellite conditions can reduce the ground test verification,shorten the satellite development cycle and save the costs significantly.This research work can provide reference for the design optimization of satellite thermal control.
Thermal Stability Optimization Design and Thermal Deformation Analysis of Space Antenna Structure Based on Representative Volume Element Method
MA Jian, XIAO Gang, XIAO Pengfei, CAI Yaning, RAN Zhiguo
2016, 36(3): 386-394. doi: 10.11728/cjss2016.03.386
Abstract(1320) PDF 1941KB(939)
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High temperature gradient and severe temperature variation in spacecraft will induce spacecraft thermal expansion and deformation.Thermally induced deflections of reflector have much effect on the electric performance of antenna on satellite that has a great limit in surface precision. Obviously,the research of in-orbit temperature and thermal distortion for antennas on satellites is very important.In this paper,the thermal stability of space antenna structure is designed and analyzed by RVE (Representative Volume Element) method.The Coefficient of Thermal Expansion (CTE) is predicted by RVE mode and experiment is also carried out.Comparison between the predicted results and experimental data verifies the rightness of this model.Optimization models for space antenna structure are created,and both the longitudinal and transverse CTE are considered. Analyzed results show that this optimized support structure and the whole antenna have an excellent thermal dimensional stability.
Design and Realization of Charge Measurement System Based on VA32TA5
REN Yiwen, GUO Jianhua, WANG Shen
2016, 36(3): 395-400. doi: 10.11728/cjss2016.03.395
Abstract(1437) PDF 822KB(902)
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Semiconductor detector has lots of advantages,such as good resolution,high sensitivity and wide linear range,which make it the most widely used detector in space exploration of X/γ Ray.Semiconductor detection system has strict requirements on its electronics system's noise level and measurement accuracy.Aiming at these requirements,a new charge measurement system based on the multi-channel charge measurement chip VA32TA5 is designed.This paper gives a detailed introduction of the system's design principle and implementation procedure,and also gives the preliminary results of performance at the end.Testing results indicate that the system has low noise and good linearity and therefore can be applied to semiconductor detectors,e.g.silicon strip detector,CdZnTe detector.
An Improved Theta* Algorithm Based on Terrain Directional Traversability
WANG Qiong, YU Dengyun, JIA Yang
2016, 36(3): 401-406. doi: 10.11728/cjss2016.03.401
Abstract(1560) PDF 1610KB(853)
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An improved any-angle path planning algorithm based on Basic Theta* algorithm is proposed.Utilizing the difference between the pitch and roll anti-overturning stability of planetary rover,terrain traversability relevant to rover heading is analyzed to distinguish obstacles and directional obstacles.Based on the obstacle map,the visibility check in node-expanding process of Basic Theta* is improved to a traversability check,hence paths that could traverse directional obstacles could be screened.Simulation experiments show that,the proposed algorithm overcomes the limitation of Basic Theta* as well as it could utilize rover characteristics more thoroughly and find the shortest path on complex terrains which are not traversable in traditional methods.It extends the rovers'range and working capability,hence it is practical for rough terrain trek,exploration of the bottom of crater and such special missions on planetary surface.
Star Point Energy Center Correction of Star Simulator Based on Polar Coordinates
WANG Lingyun, WANG Xinghua, WANG Bo, ZHANG Guoyu, SUN Gaofei, LIU Shi, LI Wenjun
2016, 36(3): 407-412. doi: 10.11728/cjss2016.03.407
Abstract(913) PDF 714KB(916)
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In this paper,various aberrations have been analyzed.Not only the effects of aberration on geometrical center position are taken into account,but also the deviation of displayed star position energy center caused by aberration is analyzed.These two aspects have been taken into comprehensive evaluation and star position correction.The correction method based on polar coordinates is proposed,and cumbersome partition correction and calculated quantity based on two-dimensional coordinates can be simplified.The experimental results show that the correction processing based on polar coordinates is simpler and easier compared with any other correction methods.In addition,the correction results are significantly more accurate.

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