空间科学学报

2016 Vol. 36, No. 1

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Study on Force-influencing Factors and Spatial Distribution of Lunar Regolith Particles under Vacuum Environmentormalsize

SHAO Yiqi, CUI Yuhong, ZHENG Gang, YU Wei, REN Depeng, YE Qing

2016, 36(1): 1-11. doi: 10.11728/cjss2016.01.001

Abstract(1307) PDF 2516KB(1153)

Abstract:
For the interaction between the regolith particles raised by lunar lander and plume, the main factors of regolith particles force in the plume are analyzed. The formula and scope of the drag, lift and gravity forces on regolith particles are also discussed. These forces were computed by magnitude analysis, and the main forces impacting the lunar soil particle motion and spatial distribution are analyzed. Particle Reynolds number, Knudsen number and the porosity, related to the inertia correction factor f_I, surface slip correction factor f_C and the correction factor f_F affected by the surrounding particles, in the plume field distributions were calculated, and effects of the three correction factors of lunar soil particle velocity and spatial distribution are also discussed. Results show that the longitudinal velocity of lunar soil particles and the maximum height of the lunar regolith particles can raise decreases slightly after f_I and f_F correction, while the impact of f_C correction is not obvious.

Analysis of the Properties of Solar Active Regions and the Solar Flares during 1996—2008ormalsize

LU Yangping, ZHAO Haofeng, LE Guiming, YIN Zhiqiang, CHEN Minhao, LI Zhongyi

2016, 36(1): 12-17. doi: 10.11728/cjss2016.01.012

Abstract(1390) PDF 790KB(884)

Abstract:
The total number of solar Active Regions (AR) N_t that occurred during 1996—2008 is 3067. And 58.52% of the N_t are the AR with the area satisfying the condition 10μh ≤ S≤90μh, 31.43% of the N_t are the AR with the area satisfying the condition 100μh ≤ S≤490μh. The AR with area S≥500μh only accounted for about 6% and the ARs with area S≥1000μh only accounted for about 1% of the total AR. The AR with area being 0 accounted for 4.01%. For each year during 1996—2008, the ratio of AR with different area S to the total number of AR usually reached its maximum at the time several years after solar maximum except the AR with area S≤ 50μh. The number that can produce at least one solar X-ray flare during 1997—2008 is 1408. The total number of C-class flares is 7706, while the total number of M-class flare is 1141 and the total number of X-class flare is 110 during 1997—2008. The sum of time integral of X-ray flux in 1～8Å produced by all C-class, M-class and X-class flares are 22.711, 29.443 and 36.178 J·m^-2. The Soft X-Ray (SXR) flare activities in the southern hemisphere are stronger that in the northern hemisphere during Solar Cycle 23.

Statistics on the critical frequency of ionospheric sporadic E layer observed at Puerto Rico region

WANG Xixi, FANG Hanxian, NIU Jun, WANG Sicheng

2016, 36(1): 18-24. doi: 10.11728/cjss2016.01.018

Abstract(939) PDF 2707KB(964)

Abstract:
The Es property in Puerto Rico region (18.5°N, 67.2°W) has been investigated using the Es critical frequency during 1997—2013. Results show that the diurnal average critical frequency presents a weak 16-day period which may be caused by the planetary wave. The critical frequency variation with local time has also been investigated which presents a valley (at about 06:00LT) and a peak (at about 14:00LT) structure. Two anomalous peaks exist after the midnight and sunset, respectively. The phenomenon is considered as a result of downward electron flux caused by the diedown of southward wind field and variability of electric field during the nighttime. It has also been found that the incidence of Es with lower strength is clearly different from those with medium and higher strength, and it can be attributed to the tidal wind. These physical mechanisms need to be proved by both observations and further mechanical investigation.

Phenomena excited by ionospheric heating observed on DEMETER satellite

ZHANG Xuemin, FROLOV V L, SHEN Xuhui, RUZHIN Y, ZHAO Shufan, ZEREN Zhima, XU Weidong, QIAN Geng

2016, 36(1): 25-39. doi: 10.11728/cjss2016.01.025

Abstract(1406) PDF 6694KB(1183)

Abstract:
The phenomena of ionospheric perturbations during the experiments between SURA and HAARP heating facilities with DEMETER satellite have been summarized, and the main disturbed electromagnetic signals have been found, including the radiated HF pump wave and sideband pump wave, enhanced VLF transmitter signals and extended frequency band, modulated ULF/ELF/VLF wave, ELF electromagnetic emissions, ULF resonant wave, perturbations in plasma parameters and precipitation of high energy particles. Then the occurrence frequency of each kind of phenomenon is studied, in which the radiated pump waves were with high occurrence probability of larger than 68%, while other disturbances detected by satellite were with low probability of smaller than 40%, and some even occurred occasionally under specific condition, owing to the effects of local ionosphere background and modulated mode, etc. Finally, combined with the orbit design and payload installation on China Seismo-Electromagnetic Satellite (CSES), some suggestions have been provided on future experiments between ionospheric heating facility with CSES on the basis of the statistical results, in order to avoid the problems and improve the successful experimental probability as much as possible.

Enhancement of High Energy Electron Fluxes and Variation of Atmospheric Electric Field in the Antarctic Region ormalsize

LI Renkang, CHEN Tao, LUO Jing, ZHOU Limin, HE Zhaohai, WANG Chunqin, SUN Yueqiang

2016, 36(1): 40-48. doi: 10.11728/cjss2016.01.040

Abstract(1221) PDF 2306KB(1056)

Abstract:
High-energy electron precipitation in the high latitude regions enhances the ionization of the atmosphere, and subsequently increases the atmospheric conductivities and the vertical electric field of the atmosphere near the ground as well. The High-Energy Electron Flux (HEEF) data measured by the Fengyun-3 meteorological satellite are analyzed together with the data of near-surface atmospheric vertical electric field measured at the Russian Vostok Station. Three HEEF enhancements are identified and it is shown that when the HEEF increases to a certain level, the local atmospheric vertical electric field near the ground can increase substantially than usual. The response time of the electric field to HEEF enhancement is about 3.7 to 4 days.

Effects of Thunderstorms Electric Field on Intensity of Cosmic Ray Electronsormalsize

ZHOU Xunxiu, WANG Xinjian, HUANG Daihui, JIA Huanyu

2016, 36(1): 49-55. doi: 10.11728/cjss2016.01.049

Abstract(1060) PDF 1762KB(910)

Abstract:
Correlation study on the intensity change of the cosmic rays and the thunderstorms electric field is very important in understanding the acceleration mechanism of secondary charged particles caused by electric field. In this paper, Monte Carlo simulations were performed to study the effects of the thunderstorms electric field on the electrons in extensive air showers. High up in the atmosphere, the number of electrons increased exponentially in a field of 1000V·cm^-1. And at an atmospheric depth about 300g·cm^-2, the electrons reached a maximum. These results were consistent with the theory of Relativistic Runaway Electron Avalanche (RREA). The simulations also indicated that in order to obtain a clearly observable effect in the ground experiments, the thunderstorms electric field should be located not higher than 600m above the detector, and the length of the electric field should be about 2000m. These preliminary results are helpful to understand the correlation between the thunderstorms electric field and the electron intensity of ground cosmic rays, and provide important information to further study of the effects on secondary cosmic ray particles in thunderstorms electric field.

Study on Atmospheric Window of Millimeter Wave Propagation in Near Space Plasma Sheathormalsize

JIANG Jin, CHEN Changxing, ZHOU Tianxiang, LING Yunfei, CHEN Ting, REN Xiaoyue

2016, 36(1): 56-62. doi: 10.11728/cjss2016.01.056

Abstract(1456) PDF 1428KB(1044)

Abstract:
The communication blackout usually happens when the reentering vehicles and hypersonic aerocraft voyage in the near space. According to the data provided by Radio Attenuation Measurement C (RAM C) voyage experiment, a model of plasma sheath will be established to analyze the parameters of plasma including plasma thickness, plasma density and plasma collision frequency to get the reflection and attenuation properties of millimeter wave atmospheric window propagation in plasma sheath, through the method of numerical calculation. The analysis by synthesis shows that the 35GHz, the window of atmosphere, in Ka waveband can be selected as communication waveband used in near space main communication platform, and subsidiary of 0.22THz in terahertz waveband space-based communication platform. It will carry on the real-time measurement and control when the reentering vehicles and hypersonic aerocraft voyage in the near space.

Wnt3a/β-catenin Signaling Pathway Mediates Inhibition of Proliferation of Mesenchymal Stem Cells Induced by Modeled Microgravity

YANG Xianjiong, MAO Xinjian, LUO Qing, SONG Guanbin

2016, 36(1): 63-69. doi: 10.11728/cjss2016.01.063

Abstract(1319) PDF 1871KB(964)

Abstract:
Microgravity is known to play an important role in regulating the proliferation of Mesenchymal Stem Cells (MSC). However, information regarding the molecular mechanisms that link microgravity and MSC proliferation is still limited. In this study, using a parallel-plate clinostat to simulate microgravity effect, we examined the effect of Modeled Microgravity (MMG) on the proliferation of bone marrow-derived MSCs and the possible role of Wnt3a/β-catenin signaling pathway in this process. The results showed that MSCs subjected to MMG for 3 days exhibited significantly decrease of cell proliferation. Moreover, MMG weakened mRNA expression of Wnt3a, reduced unbound β-catenin in cytoplasm and subsequently inhibited the translocation of β-catenin into nucleus. Expression of Cyclin D1 at mRNA level in MSCs was also impaired after treatment with MMG. These results suggest that Wnt3a/β-catenin signaling pathway may be mediate inhibition of proliferation of MSCs induced by MMG.

Post-Newtonian Model of High-precision Inertial Navigation in Space ormalsize

FEI Baojun, HE Zhenni, DU Jian

2016, 36(1): 70-76. doi: 10.11728/cjss2016.01.070

Abstract(1039) PDF 964KB(1097)

Abstract:
The concept of inertial system in general theory of relativity is introduced to inertial navigation using post-Newtonian theory of gravity, and a new model of inertial navigation of spacecraft is proposed. It utilizes the geodesic motion objects around the Earth as the follow-up inertial frame of reference. The special force and gravity gradient measured by accelerometers in spacecraft are employed as the observable, and navigation can be realized by solving the status of the spacecraft relative to the follow-up inertial frame. The method used for high orbit satellite can obtain high measurement accuracy, and its errors mainly come from the measurement accuracy of inertial components as well as the design of geodesic trajectory. There is no error accumulated over time which has existed in current inertial navigation model.

Positioning of high Earth orbit satellite using GPS/Beidou combined system

ZHAO Yanzhen

2016, 36(1): 77-82. doi: 10.11728/cjss2016.01.077

Abstract(1024) PDF 1024KB(1023)

Abstract:
The characteristics of current high orbit GPS (Global Positioning System) signal are of poor availability and low positioning accuracy. Positioning of high Earth orbit satellites using GPS/Beidou combined system is studied. The visibility of navigation satellites and the Geometric Dilution of Precision (GDOP) are analyzed. Through simulation and analyzing, it is verified that the GPS/Beidou combined system has better performance than that of single GPS system. On one hand, the GPS/Beidou combined system can receive more satellites' signal than single GPS system. On the other hand, GDOP of the GPS/Beidou combined system is smaller than that of single GPS system. At the same time, the use of high-precision atomic clock in the satellite receiver can realize positioning of three satellites, and reduce the technology requirements of receiver.

Motion simulation and function test on repeated fold-unfold mechanism of fan-shaped solar array

HU Ming, LI Wenjuan, CHEN Wenhua, TIAN Fangfei, ZHANG Yang

2016, 36(1): 92-98. doi: 10.11728/cjss2016.01.092

Abstract(1389) PDF 1797KB(3607)

Abstract:
The traditional folding solar array with large size and big mass, using single deployment and locking mechanism, can cause flutter during the spacecraft attitude adjustment or orbital transfer, and hence a fan-shaped solar array with repeated fold-unfold and lock-unlock mechanism scheme was designed. A virtual prototype model is established based on ProE/Adams co-simulation, and the motion parameter changing rule of the pivot panel at different motor rotational speeds is obtained. The deployment function verification test is carried out using the prototype. By comparing the simulation result with the test data, it can be known that the mechanism can be fully deployed and locked in time when the motor speed is changed in prescriptive range, and can be deployed and locked repeatedly. The simulation result is highly consistent with the test data, which shows that the design can meet the requirements.

Design of a New Type of Nb-W Alloy and Its High-temperature Oxidation Resistance Coating Used in the Field of Spacecraft Engineormalsize

ZHOU Xiaojun, ZHAO Gang, TIAN Jinpeng

2016, 36(1): 99-105. doi: 10.11728/cjss2016.01.099

Abstract(1464) PDF 3329KB(985)

Abstract:
The superalloy and protective coating is a major trend of material used in spacecraft engine. With the rapid development of space exploration technologies, it is very important to design a new type of Nb-W alloy and its coating used in the field of spacecraft engine for the upgrading weight ratio and operating temperature. This study controls the ratio of Nb, W, Zr and other elements to sintering and gets a new type of Nb-W alloy Nb521-1 with excellent mechanical properties at high temperature by electron beam furnace smelting. Using slurry firing, the silicide complex coating was prepared on the surface of Nb521-1 alloy. The morphology of the composite coating was investigated by SEM. The life of high temperature oxidation resistance is at least 50 hours at 1700℃ and 9 hours at 1800℃. The limit time of shock-testing from room temperature to 1600℃ is more than 2500 times. Complex coating achieves the goal of high temperature oxidation resistance protection. Products have been successfully applied in aerospace materials.

Study on 3D Subdivision Mode and Encoding in Heliocentric Coordination Systemormalsize

HU Yasi, SONG Junjun, SHI Peng, DUAN Ran

2016, 36(1): 106-116. doi: 10.11728/cjss2016.01.106

Abstract(864) PDF 5136KB(1065)

Abstract:
With the ever-increasing of space data, a reasonable data-arrangement is strongly required for high efficiency in data accessing and visualization. In this paper, basing on the characteristics of solar-wind data, a SDOG-R grid model is employed, which is radial independent division in the adaptive SDOG grid. For huge Sun-Earth space, it is divided into multi-resolution grids. The original data, which is output from a SIP-CESE solar wind model, are re-sampled, and put into the subdivided grids. The grid model is applied to both regular and irregular sampling data, and fully maintains the characteristics of original data to the best and encodes grids with an improved CDZ curve. Specific examples of data organization are given. The experiments prove that the grid model not only resolves the problem that grids are too dense at two poles and the spherical center, but also meets the need for higher resolution in radius than in latitude and longitude. Besides, 3D LOD spatial data model can not only provide multi-resolution data, but also significantly improve the large-scale mass data retrieval and access efficiency, and can support the organization and management of massive spatial data effectively.