Secular Effect of Geomagnetic Field and Gravitational Waves on Earth’s Satellite Orbits

In this work we study the perturbation and the change in the orbital elements due to the earth’s magnetic field and the gravitational waves. The acceleration components are derived in the radial, transverse to it and normal to the orbital plane. The equation for the rates of variation of the elements is formed and solved to find the secular variation in the element for polar and equatorial satellites.

Synthetic tidal parameters for gravity over China and its neighbor area

The synthetic tidal parameters with high spatial resolution for gravity over China and its neighbor area are constructed with Earth＇s tidal model and ocean tide loading calculated using TPXO7 global ocean tide model as well as tidal data over China seas. The comparison between synthetic parameters and ones observed by spring gravimeters at some seismic network stations and Hong Kong station and one observed by super-conducting gravimeter at Wuhan station shows that the average differences in amplitude factors and phases are smaller than 0.005 and 0.5° respectively; and that the discrepancies between observational and synthetic parameters are dependent on gravimetric technique in that the synthetic parameters are in well agreement with the superconducting gravimetric observations. This also indicates that the synthetic result is a good estimation for tidal gravity, and the numerical results in the present paper not only can provide ground and space gravimetry such as absolute gravimetry with correction model of tidal gravity, but also provide effective tidal parameters over areas where no observation is carried out.

An improved frequency shift method for ATI-SAR flat earth phase removal

An improved frequency shift method is proposed to remove the flat earth phase in ATI-SAR ocean surface motion detection in this study. First, two conventional flat earth effect removal methods(i.e., the frequency shift method and the orbital parameter method) are introduced and compared. Then, two improvements to frequency shift method are suggested. In the first improvement, the phase diagram is divided into several sub-blocks to calculate the phase fringe frequency. In the second improvement, a function between the phase of land regions and position is fitted to correct the residual flat earth phase based on the phase of the land regions that tend toward zero in an along-track interferogram. It is found that the improved frequency shift method is greatly improved;and it agrees well with the orbital parameter method, and achieves similar accuracy.

Design and analysis of the Macao Science Satellite-1's laser retro-reflector array

The origin and spatial-temporal variation of the Earth’s magnetic field(EMF)is one of the important scientific problems that has long been unsolved.The Macao Science Satellite-1(MSS-1)under construction is China’s first high-precision EMF measurement satellite.To satisfy the highly precise requirements of the MSS-1 orbit measurement,a light,high-precision,four-prism laser retroreflector array was designed.It weighs approximately 285 g,its effective reflection area is greater than 1.77 cm^(2),and its size is 100×100×41 mm.The laser retro-reflector array has excellent performance,and it can achieve a ranging precision at the subcentimeter level for satellite laser ranging.It will be developed and installed on the MSS-1 as a power-free load for high-precision orbit measurement and accurate orbit calibration.The MSS-1 is planned to be brought into the International Laser Ranging Service observations.More than 31satellite laser ranging stations in the International Laser Ranging Service around the world will be able to measure the MSS-1 with long arcs,which will support the scientific mission of high-precision EMF exploration.

Effect of Altitude, Right Ascension of Ascending Node and Inclination on Lifetime of Circular Lunar Orbits

The lifetime of a lunar satellite orbit is constrained by the non-spherical nature of the Moon’s gravity field. The orbital lifetime of lunar orbits depends significantly on the initial conditions of the orbit. Right ascension of ascending node (Ω) is one of the important orbital parameter affecting the orbital lifetime. In the present work we have analyzed the effect of Ω on the variation of lifetime with altitude for circular lunar orbits. It is found that at a particular initial altitude, a small increase in the altitude results in substantial increase in the orbital lifetime due to effect of the long periodic terms of Earth’s gravity on eccentricity and this transition altitude is different for different Ω. Further, it is observed that the variation of transition altitude with Ω follows a definite, but different trend for orbits with different inclinations. The transition altitude for polar orbits is found to be higher without the effect of Sun and Earth gravity. Variation of transition altitude with orbital inclination is also analyzed. Lifetimes of high altitude circular lunar orbits are analyzed and it is observed that at high altitudes lifetime decreases with altitude.

Numerical simulation of the sensor output on Macao Science Satellite-1

Macao Science Satellite-1(MSS-1)will be launched at the early of 2023 into a near-circular orbit.The mission is designed to measure the Earth’s geomagnetic field with unpreceded accuracy through a new perspective.The most important component installed on the satellite,to ensure high accuracy,is the deployable boom(Optical Bench).A Vector Field Magnetometer(VFM),an Advanced Stellar Compass(ASC),and a Couple Dark State Magnetometers(CDSM)are deployed on the deployable boom.In order to maximize the mission’s scientific output,a numerical simulator on MSS-1’s deployable boom was required to evaluate the adaptability of all devices on the deployable boom and assist the satellite’s data pre-processing.This paper first briefly describes the synthesis of the Earth’s total magnetic field and then describes the method simulating the output of scalar and vector magnetometers.Finally,the calibration method is applied to the synthetic magnetometer data to analyze the possible noise/error of the relevant instruments.Our results show that the simulator can imitate the disturbance of different noise sources or errors in the measuring system,and is especially useful for the satellite’s data processing group.

星基并置轨道配置对地球自转参数解算的影响

为了进一步研究全球卫星导航系统(GNSS)和卫星激光测距(SLR)低轨卫星(LEO)星基并置对于地球自转参数(ERP)解算的贡献,综合评估星基并置轨道配置和空间连接误差对地球自转参数解算的影响:通过仿真实验,联合地面全球定位系统(GPS)、低轨卫星星载GPS,以及低轨卫星激光测距观测数据,分析低轨卫星轨道配置、空间连接误差对地球自转参数解算精度的影响。结果表明,ERP的估计精度受低轨星基并置站的轨道高度和倾角影响较为明显;相比于低轨道、低倾角卫星,高轨道、高倾角卫星对于极移参数的解算精度提升效果更为显著,这主要是得益于该轨道配置可提供更多的SLR观测数据;此外,空间连接误差分析结果表明,ERP对于低轨卫星SLR棱镜质心改正的误差更加敏感,特别是在Z向,2 cm的Z向SLR棱镜质心改正误差可使得极移X分量和Y分量的估计精度分别下降24%和14%。

两种GPS广播星历参数算法的比较

介绍了新GPS广播星历参数,分析了新旧GPS广播星历参数及其用户算法的区别,导出了卫星位置矢量对新GPS广播星历参数的偏导数,并与旧GPS广播星历参数偏导数进行了简要的比较分析．计算结果表明,两种GPS广播星历参数算法都能很好地描述MEO卫星的轨道特性,且广播星历参数拟合算法的精度损失仅为数厘米．

基于椭圆轨道的Geo-SAR精确多普勒参数解析计算方法

该文综合考虑了轨道偏心率、地球扁率和地球自转三方面的因素,推导得出高精度星载SAR多普勒中心频率和多普勒调频率解析式。鉴于2维姿态导引对于Geo-SAR的必要性,进一步分析了姿态导引后和零姿态导引两种情况下的多普勒参数,为Geo-SAR的多普勒参数计算提供了实用且有效的方法。该文得到的多普勒参数解析计算式适用于任意轨道高度和任意姿态的星载SAR,且具备很高的精度。基于该结论,研究了运行于椭圆轨道的Geo-SAR多普勒中心和多普勒调频率特性。

基于参数识别应用Backstepping design控制Lü′s混沌吸引子

混沌控制在最近十几年的研究中已经取得了长足的进展,形成了许多比较成熟而且有效的控制技术和方法,如:OGY控制、线性状态空间反馈等 但对于带有未知参数的系统,前面提到的方法常常无法达到预期的控制 通过构造识别函数识别L櫣′s混沌系统的未知参数,然后应用Backsteppingdesign控制L櫣′s混沌吸引子,将L櫣′s混沌吸引子控制到一个稳定的周期轨道。

我国将来更高精度CSGM卫星重力测量计划研究

基于卫星跟踪模式的优化选取、关键载荷的优化组合、轨道参数的优化设计、仿真模拟的先期启动和反演方法的优化改进，开展了我国将来CSGM（China’SSatellite Gravity Mission）卫星重力测量计划实施的研究论证。由于卫星跟踪卫星高低／低低（SST-HL／LL）模式对地球中长波重力场的探测精度较高、技术要求相对较低，而且可借鉴当前GRACE卫星的成功经验，因此建议将来CSGM卫星重力测量计划采用SST-HL／LL模式；建议开展激光干涉星问测距仪、复合GPS接收机、非保守力补偿系统、卫星体和加速度计质心调节装置等关键载荷的先期研制；建议将来CSGM卫星的轨道高度（300～400km）和星间距离（100±50km）选择在已有重力卫星的测量盲区；建议将仿真技术应用于CSGM卫星的方案论证、系统设计、部件研制、产品检验、空中使用、故障分析等研发和运行的全过程；对比分析了卫星轨道摄动法、动力学法、能量守恒法和加速度法的优缺点，建议寻求新型、高精度、高效率和全频段的卫星重力反演方法；提出将来CSGM卫星重力测量计划的预期科学目标：在300阶处，累计大地水准面精度和累计重力异常精度分别为1～5cm和1～5mGal。

等效斜视距离模型在星载LEO-SAR中的精度分析

该文旨在研究等效斜视距离模型在低轨星载SAR高分辨率情况下的适用性,并分析其最佳性能——即该模型适用的最长合成孔径时间及对应的最高分辨率。该文首先通过建立精确的"星-地"几何模型推导出具有较高精度的多普勒中心和多普勒调频率计算公式,进而通过多普勒参数反演得到等效斜视距离模型。通过与数值方法得到的斜距信息比较,可以得到该距离模型拟合结果的误差,当该误差在p/4阈值之内,图像就不会散焦。利用该思想,该文以TerraSAR-X参数为例,分析了等效斜视模型可以适用的最长合成孔径时间及对应的最高分辨率。该文结论给一般的低轨星载SAR距离模型分析提供了一种普适的方法。

地球同步轨道双基SAR成像方法

地球同步轨道发射、低地球轨道接收体制的天基雷达系统具有观测范围广、抗摧毁和抗干扰能力强、组网灵活等优点。分析发现,该系统中回波的包络不仅与地表场景的斜距有关,还与其方位位置有关,传统的单基SAR成像方法不再适用。本文分析了回波包络的历程,给出了适用于该系统的SAR成像方法。该方法根据多普勒参数以及目标像的几何形变量随接收卫星与发射卫星几何位置关系的变化特征对数据沿方位以及距离向进行分块,并重新构造距离徙动校正和方位匹配函数对回波信号聚焦,最后进行几何形变校正。仿真数据的成像结果证明了方法的可行性。

Ka波段大回旋电子注介质加载回旋行波管输入耦合器研究

针对Ka波段大回旋电子注回旋行波管设计了一个TE 21模式输入耦合器。该输入耦合器结构为Y形功分器,将输入的矩形波导TE 10模式转换为圆波导的TE 21模式进行输出。本文对其转换原理进行了简要介绍,通过仿真确定了输入耦合器模型的参数,并加工出部件,并进行了实际测试,测试的结果满足Ka波段大回旋行波管的信号输入要求。

定量研究地球轨道参数和温室气体浓度变化对中全新世气候的影响

依据最新的古气候耦合模式比较计划(PMIP4)协议,利用完全耦合的气候模式CESM1.0,研究中全新世与工业革命前气候的差异,量化地球轨道参数(ORB)和温室气体(GHG)对中全新世气候变化的影响。3个模拟试验结果表明,与工业革命前相比,中全新世北半球高纬度地区气候偏温,全球其他地区气候偏冷,北半球大部分地区更湿润,南半球则较为干燥;ORB导致全球中高纬度地区升温,GHG在降低全球气温和减少中高纬度地区降水方面发挥作用;这种差异引起大气和海洋环流的变化,导致地球经向热量输送的差异;就总经向热量输送的变化范围而言,ORB对气候的影响大约是GHG的5倍。研究结果对深入了解中全新世气候及其对不同外部强迫的响应有积极意义。

Some advancements in measurements of physical parameters of earth's material at high temperature and ultrahigh pressure

IT is very important to measure physical parameters of minerals, rocks, melts and fluids athigh pressure and high temperature. The data from these experiments can provide materialsfor explanation of geophysical observations on large scale, and information of geochemicalfield. Therefore, we set up measurement methods on elastic wave velocity, electrical conduc-tivity and differential thermal analysis in YJ-3000 ton press fitted with a wedge-type

From the Beginning of the World to the Beginning of Life on Earth

Hypersphere World-Universe Model (WUM) is, in fact, a Paradigm Shift in Cosmology [1]. In this paper, we provide seven Pillars of WUM: Medium of the World;Inter-Connectivity of Primary Cosmological Parameters;Creation of Matter;Multicomponent Dark Matter;Macroobjects;Volcanic Rotational Fission;Dark Matter Reactors. We describe the evolution of the World from the Beginning up to the birth of the Solar System and discuss the condition of the Early Earth before the beginning of life on it.

Geophysical and Chemical Evidence in the Depletion of Ozone

The depletion of ozone is due to not only some chemical reaction, but also some physical changes, such as Solar Proton Events with solar flare, violent vortex of air currents with the changes of the earth’s rotation caused by earth’s deformation and so on We found that the tidal force by the sun makes the earth’s oblateness large on the 0° Latitude and small on the 23 5°Latitude The tidal force by the moon and nine planets can make this effect strong This is a basic reason for the creation of ozone hole and El Nino \;As shown from calculation,the earth tide by the sun makes the earth′s deformation and rotation change periodically.When the situation of the sun moves from 23.5°N to 23.5°S,the length of a day will change±0.00027s.When the earth moves from aphelion to perihelion,the length of a day will increase 0.00007s.The earth tide by the moon can increase or decrease this effect periodically.They are the reasons of the earth′s rotation decelerating from 30 July to 16 November and the ozone hole over the south Pole sky expanding with El Nino.The SSW unified stress field of the earth is the tectonic evidence of the orbital effect of the earth′s rotation and deformation.The moon′s declination and obliquity of the ecliptic determine the direction of the principal compressive stress field. Scientists discover chlorion layer in atmosphere while they studied freon.Chlorion can fly in to atmosphere from continent and ocean in many ways.The photolyte of freon is only one way of them,such as electrolysis and photolysis of sodium chloride and hydrogen chloride.The differential rotation of the earth’s layers mix ozone with chlorion and create a ozone hole over the Qinghai Tibet plateau sky.The depletion of ozone and El Nino are the results of the differential rotation.

New Long-Term Climate Oscillations

The astronomical theory of climate change is based on the solution of differential equations describing Earth’s orbital and rotational motions. The equations are used to calculate the change in insolation over the Earth’s surface. As a result of the author’s solution of the orbital problem, the periods and amplitudes of Earth-orbit variations and their evolution have been refined. Unlike previous studies, the equations of Earth’s rotational motion are solved completely. The Earth’s rotational axis precesses relative to a direction different from the direction of the orbit’s axial precession, and oscillates with periods of half a month, half a year and 18.6 years. Also, its oscillations occur with irregular periods of several tens of thousands of years and more. All these motions lead to oscillations of the obliquity in the range of 14.7° to 32.1°, which prove to be 7 - 8 times larger than obtained by a previous theory. In the same proportion, the Earth’s insolation oscillations increase in amplitude, with insolation extremes occurring in other epochs than those in the previous theory. The amplitudes and the onset times of the extremes correlate with known paleoclimate changes. Thirteen insolation periods of paleoclimate variation over an interval of 200 thousand years are identified. From the insolation evolution calculated over a time interval of 1 million years, 6 climate gradations from very cold to very warm are identified.

地球定向参数预报误差及其对北斗三号卫星定轨精度的影响

地球定向参数(Earth orientation parameters,EOP)是地球参考系到地心天球参考系之间转换的桥梁,是卫星精密定轨过程中不可缺少的重要参数。以国际地球自转服务(International Earth Rotation Service,IERS)和中国科学院上海天文台(Shanghai Astronomical Observatory,SHAO)提供的EOP参数为例,分析了北斗三号仅区域网观测模式和星地星间联合观测模式下的定轨精度与EOP预报误差间的关系。研究表明,对于IERS提供的产品,其预报误差对仅区域站定轨模式的定轨精度影响较小,但是其10 d内的预报误差对星地星间联合定轨模式定轨精度的影响可达到分米级。对于SHAO提供的产品,两种定轨模式的定轨精度均随着EOP预报天数的增大而逐渐衰减。除此之外,不同产品的星地星间联合定轨模式下定轨精度均小于仅区域网监测下的定轨模式下的定轨精度,表明星间链路的加入可以降低卫星定轨对EOP预报误差的依赖。该研究对区域观测条件下的卫星精密定轨工程实现具有重要意义。