2006 Vol. 26, No. 2

Display Method:
Artificially Created Airglow by Neutral Gas Release
HUANG Wengeng, GU Shifen
2006, 26(2): 81-85. doi: 10.11728/cjss2006.02.081
Abstract(2155) PDF 3119KB(1001)
In case of injection of neutral gases into ionosphere, atomic oxygen ions undergo charge transfer reactions with these injected molecules. The recombination rate coefficients of molecular ion with electron are several orders greater than that of the dominant atomic oxygen ion in ionosphere F region. Therefore, rockets exhaust gases produced by engine and artificially released neutral gases in the space active plasma experiments can substantially affect ionosphere, for example, the formation of electron depletion region, which is referred to as ionospheric holes, and these phenomena have been observed in many experiments. In this paper, in terms of diffusion equation of neutral gas in thermosphere and main ion-chemistry reactions in ionospheric F region, the diffusion processes of H2, H2O and CO2 and ionospheric response to released gases are investigated. Additionally, airglow volume emission rates and intensity from the release at ionospheric altitudes are calculated The results show that the diffusion of released neutral gas in F region is very quick, and these gas molecules can cause a large-scale depletion of ionospheric electron density. At some altitudes of F region, the dominant positive ion converts into other molecular ion, such as H2O^+. During the diffusion process, airglow will be excited, and its wavelength and emission characteristics depend on the released materials.
High-Frequency Wave Excitation by the Modulated Electron Beam From Spacecraft Injected Into the Ionosphere Plasma
YANG Yong, ZHAO Zhengyu, I.O. Anisimov
2006, 26(2): 86-91. doi: 10.11728/cjss2006.02.086
Abstract(2204) PDF 1293KB(1058)
Waves excitation in the ionosphere by the modulated electron beams was observed in some active plasma experiments in space. In the active beam-plasma experiments electromagnetic wave can be excited by injecting modulated electron beam into the ionosphere, by various mechanisms according to different experimental conditions, The frequency of this sort of radioemission is determined by the beam modulation; it can lie in the whistler band or in the high frequency band (higher than electron plasma frequency). This article gives a theoretical analysis as well as quantitative calculation of the radioemission of semi-restricted thin modulated electron beam injected from the spacecraft into the ionosphere plasma along the geomagnetic field. The result shows that when the modulated electron beams are injected along the magnetic field line, they can produce high-frequency electromagnetic radiations in the ionosphere plasma. This electromagnetic radiation is mainly observed in the plane that is perpendicular to the velocity direction of the injected electron beam. Estimations show that the radiated power is high enough to be detected.
A Possible Mechanism of Typhoon Effects on the Ionospheric F2 Layer
LIU Yimou, WANG Jingsong, XIAO Zuo, SUO Yucheng
2006, 26(2): 92-97. doi: 10.11728/cjss2006.02.092
Abstract(1995) PDF 2174KB(1498)
During the period of typhoon, especially when typhoon is approaching the mainland, violent interaction between the wind and the sea surface, the wind and the mainland will greatly strengthen the turbulence in the lower atmosphere, and it will possibly raise the turbopause in altitude. Thus it will change the structure of the earth's atmosphere and influence the photochemical process of the upper atmosphere, and consequently influence the ionosphere. Based on the assumption that typhoon will raise the turbopause in altitude, the response of F2 layer of the ionosphere over the middle latitude of Japan (45°N, 142°E) was simulated, by using the one dimensional ionospheric model. The results of the simulation can qualitatively explain the following phenomena very well: f0F2 of the ionosphere will decrease while the reflecting surface in the ionosphere of the radio wave with a certain frequency will increase during the time of typhoon, hmF2 increases due to the raise of turbopause in this simulation. These results suggest that the rising in altitude of turbopause by typhoon is a very reasonable mechanism of typhoon effects on the ionospheric F2 layer.
Modification and Application of E10.7 Index in the Band of Soft X-Ray
LIAO Hairen, WANG Jingsong
2006, 26(2): 98-103. doi: 10.11728/cjss2006.02.098
Abstract(1938) PDF 2034KB(1138)
The E10.7 index representing the solar EUV irradiance flux has been used to replace the traditional F10.7 index in more and more researches and applications. X-rays are important ionization source of the terrestrial D and E layer. Due to lack of enough observation to the D layer and versatile ionization sources of E layer, it is difficult to study the influence of X-rays to terrestrial ionosphere. The dominant ionization source for the secondary layer of Martian ionosphere is soft X-ray. This makes it possible to study the X-ray influence on the ionosphere. By studying the dependence of Martian ionospheric secondary layer peak density to E10.7, it is found that even after necessary corrections, the dependences are in disagreement for different data sets. After data and theoretical analysis, a new index Xs is introduced to represents the solar soft X-ray irradiance flux. After replacing E10.7 with this Xs index, the peak density dependences upon the solar irradiance are in good agreement for different data sets, indicating Xs index is a better measure of solar soft X-ray irradiance than E10.7 index.
Simulation Study on elves in the Lower Ionosphere
WU Mingliang, XU Jiyao, MA Ruiping
2006, 26(2): 104-110. doi: 10.11728/cjss2006.02.104
A time-dependent electromagnetic field code is developed in this paper and is applied to simulate time-space characteristics of elves (emission of light and very low frequency perturbations from electro-magnetic pulse sources). The simulation results indicate the electric fields produced by thunderstorm discharge include the Quasi-Electrostatic Fields (QEF) and the radiation fields. The radiation fields, which are produced by the discharge current pulse, directly produce the elves. The distributions of radiation fields are similar to the electric fields produced by the electric dipole radiation. The radiation fields above the thunderstorm discharge are relatively weaker, but the radiation fields are relatively greater near the ground. Moreover, the simulation results show that the double or single ring structure of optical emission, which corresponds to the double or single peak structure of elves, will appear on the film of a camera. During the outward expanding process of elves at the altitude of 83km, the intensity of optical emission originally increases with the radial distance till it gets the maximum, then decreases with the radial distance. In addition to, the causes that the expanding velocity of elves is bigger than the speed of light are explored using the assumption of spherical electromagnetic wave.
A Kind of Non-Reflection Numerical Boundary Scheme for the Propagation of Atmosphere Waves
LIU Xiao, XU Jiyao
2006, 26(2): 111-117. doi: 10.11728/cjss2006.02.111
Abstract(2160) PDF 2129KB(1142)
According to the fundamental principle of non-reflection boundary conditions and considering the fact that high order numerical boundary schemes can decrease the boundary error and spurious reflections, in this paper, a high order Smooth Fitting Extrapolate Boundary Scheme (SFEBS) is proposed by using the method of the least squares for data fitting. Since the governing equations for atmosphere movement can be reduced to a convective equation, so, to verify the validity of SFEBS, the propagation of one dimensional wave packet and shock governed by convective equation are simulated and compared with the boundary scheme that is based on the idea of Taylor series expansion (TEBS hereafter). The numerical results show that, the spurious reflections that calculated by high order SFEBS is about 1/6 of that calculated by the same order TEBS. This shows that SFEBS is a better numerical boundary scheme for outflow boundary. SFEBS will be a very good numerical boundary scheme for the numerical simulation of atmosphere waves with wide spectrum.
Observation on Meteor Velocities of the Quadrantid Meteor Shower by Using the Wuhan Meteor Radar
CHEN Jinsong, NING Baiqi, WAN Weixing
2006, 26(2): 118-123. doi: 10.11728/cjss2006.02.118
The Quadrantid meteor shower and the meteor speed during the period of this meteor shower are successfully observed using the Wuhan meteor radar for the first time, and then the correlative questions of observing meteor shower using the all-sky meteor radar are also discussed. The observational result shows that this Quadrantid meteor shower occurs between 0000 to 0800 local time in January 4, 2004, with meteor echoes peaking at 0400 local time. Moreover the meteor shower radiant derived from the meteor echoes plane, which is formed by the whole meteor echoes observed by the meteor radar during this shower, accords well with the theoretic radiant of this meteor shower. The meteor speeds during this period of this shower are calculated by the amplitude Fresnel oscillation method of the meteor echoes, and then the meteor speed distribution is analyzed, revealing the meteor speed observed during this shower mainly concentrated between 10-30km/s, which is discovered to be controlled by the meteor initial velocity entering earth's atmosphere combined with the meteor decelerating process in the atmosphere. Finally the meteor speed varieties with the height are studied, from which the decelerating effects of the earth's atmosphere on the meteor bodies are discussed.
Analysis of Climatic Features of the Zonal Winds in the Middle Atmosphere Over East Asia by Using HRDI/UARS Data Set
PENG Yonggang, CHEN Zeyu, CHEN Hongbin, WANG Zhenhui
2006, 26(2): 124-131. doi: 10.11728/cjss2006.02.124
Abstract(2048) PDF 3757KB(1138)
In this paper, the long term mean characteristics of the zonal winds in the middle atmosphere over East Asia were studied by using the HRDI/UARS measurements. The results of 7-years averaged data analysis showed that the middle atmospheric zonal winds exhibit significant regional features when compared with the CIRA-86 counterpart that has been widely used. In the region, the winter mesospheric westerly jet lies at 75 km altitude and in between 25°-35°N, which is 10 km higher and 5° farther south in latitude that of the CIRA-86. While not shown in CIRA-86, there is a clear easterly band extending from the equator to high latitudes at the altitude of lower thermosphere in autumn. Further investigation revealed the presence of considerable regional scale disturbances in the whole of the middle to upper atmosphere over East Asia, except the situations in mid-latitudes in summer. In winter, the tropical lower thermospheric zonal winds fluctuate significantly in zonal direction, and this kind of the zonal disturbances extend downward to 55 km altitude (the lower limit of the observation mode of the satellite instrument) in summer. With respect to the situation in mid-latitudes, very few zonal fluctuation can seen in the zonal winds from 55 km to 115 km altitude range in the summer season, however, the winter mesospheric and lower thermospheric zonal winds are disturbed prominently in the zonal.
Research of Circuit System in CCD Ultraviolet Sensor for Probing Moon
GONG Dezhu, JIA Jinzhong, LIU Yang
2006, 26(2): 132-141. doi: 10.11728/cjss2006.02.132
Abstract(2352) PDF 4775KB(1192)
The research and development of CCD circuit, including both hardware and software are introduced in this paper. This circuit will be employed in the Ultraviolet Sensor (UVS) system of CE1 satellite, which is one of Chinese projects of detecting the moon. UV CCD sensor is made of optical structures, CCD and its processing circuit, Data Process Unit (DPU) and its software. The light of incidence goes iuto CCD, reflected by ichnographic mirror and thrilling through lens, and is transformed to digital signal by video processing circuit. The digital image signal is stored in data memory, and is analyzed by DPU. The calculated moon center is transformed to the attitude angle of detector to moon finally. UVS CCD circuit system includes CCD circuit, timing circuit, driver circuit, video process circuit and power circuit. The key device (CCD) is CCD48-20 from E2V company. It is detailedly introduced about CCD's timing and driving, smear problem, and so on.
A New Autonomous Navigation Method for Martian Rover Based on Celestial Observation
NING Xiaolin, FANG Jiancheng
2006, 26(2): 142-147. doi: 10.11728/cjss2006.02.142
Abstract(2167) PDF 1576KB(1013)
It is essential for a Martian rover to know its position in order to fulfill a task. For there are some disadvantages of the rover controlled and navigated by ground station. The autonomous navigation and control of planet rover have become an important topics. Since the celestial navigation method has become one of the main trends of mobile robots navigation development, a new Autonomous navigation method for Martian rover based on celestial observation is described in this paper. This method only uses the angles between the stars and the center of Martian moons, Phobos or Deimos, which are got from an image of such objects taken by a star camera. At a given time these angles contains the information of rover's position, we can determine the position of Martian rover by the UPF (Unscented Particle Filter) method combined with the rover motion model. A simulation result demonstrated the validity and feasibility of this new method. The main factors which affect the precision, including measurement error and ephemeris error, are also analyzed.
Satellite Formation Establishing in Near Circular Orbit
MENG Yunhe, DAI Jinhai
2006, 26(2): 148-154. doi: 10.11728/cjss2006.02.148
Abstract(1908) PDF 996KB(1218)
Based on the assumption of near circular orbit, a method to establish a formation flying with multiple satellites in the same point of orbit-intry was discussed. Firstly, from Gauss' equations and relative motion equations, the relation of control impulse and relative motion was expressed as analysis formulas and simplified based on the near circular condition. By deeply analyzing the mechanism of impulses in each directions (radial, in-track and cross-track directions) effect on relative motion respectively, two maneuvers to establish formation flying are provided: one is to utilize the impulses in radial and cross-track directions, the other is to utilize the impulses in along-track and cross-track directions. Both of the two methods can establish satellite formation flying of any configuration. The method with impulses irradial and cross-track directions needs only 3 impulses, while the method with impulses in along-back and cross-track directions needs 4 impulses. Lastly, by an example of establishing a space-circle formation flying, two maneuvers were compared with each other in the amount of impulses and fuel consuming estimation. Simulations show that the methods are simple and practical, which could solve the establishing problem of satellite formations on near circular orbit easily.
Study on Deorbit of Satellites of LEO and Constellation
XIAO Yelun, LI Chenguang, CHEN Shaolong
2006, 26(2): 155-160. doi: 10.11728/cjss2006.02.155
Abstract(2529) PDF 1256KB(1155)
One of the measures of Space Debris Mitigation is to execute a deorbit maneuver after the mission of LEO completed, and the satellites die out gradually by the drag of atmosphere in 25 years. Some fuels are needed in deorbit maneuver, so deorbit maneuver must be considered in the phase of satellite overall design. The relations of orbital parameters of LEO, cost of deorbit maneuver and existent lifetime must be studied deeply. The theories and methods of solving deorbit maneuver are explained. A highly effective method of calculating orbit lifetime is introduced: method of differential-integral, and its correctness and validity are validated. The relation of aftermission orbit lifetime and expense of deorbit maneuver is studied. The positive question and the contrary question are presented and solved. The infections of other factors such as F10.7 and s acting on those relations are studied, and estimate values are provided. Some computing results are provided, and are analyzed and summarized. An applied method dealing with question of deorbit maneuver is provided for the design of LEO.