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11.
为了模拟位于地月系L2点的中继星"鹊桥"与月球的位置关系,进而估算中继星激光测距的成功率,按照轨道周期约为14天的要求对中继星所在的晕轨道进行计算,建立了一个综合考虑望远镜抖动、大气抖动和预报轨道横向偏离的模型。从数值上给出了一条轨道周期为14. 78天,X方向(地月连线方向)振幅为12 493 km,Y方向为34 596 km,Z方向(垂直于地月轨道平面方向)为11 916 km的周期轨道。由于晕轨道的最小振幅远大于月球遮挡的临界振幅4 000 km,因此月球对中继星不存在遮挡问题。基于建立的测距成功率模型,根据昆明站(国际编号:7820)的激光测距系统对运行在该轨道上的中继星进行测距成功率分析,结果表明:测距成功率随着中继星横向轨道标准差的增大呈快速降低的趋势。对于中继星到测站的平均距离而言,当中继星没有横向偏离时,探测器产生的光电子数为0. 151,成功率为14. 07%;横向偏离2 km时,光电子数降为0. 035,成功率降为3. 46%。对比最近距离与最远距离的情况,无横向偏离的情况下,探测器产生的光电子数从0. 174降为0. 139,成功率从16. 01%降为13. 02%。该计算结果可为云南天文台1. 2 m望远镜实现中继星激光测距提供参考。 相似文献
12.
YANG Yuanxi & WEN Yuanlan . Xi''''an Research Institute of Surveying Mapping Xi抋''''an China . College of Aerospace Material Engineering National University of Defense Technology Changsha China 《中国科学D辑(英文版)》2004,47(7):585-592
The precise orbit information is the premise of the application of satellite, and the precise orbit deter- mination includes dynamic and geometric methods. The dynamic method estimates the position and veloc-ity of a satellite at one epoch by extending the obser-vational arc in order to include more observations of different epochs in it. It is realized by integrating the dynamic equation of the satellite so that the observa-tions at different epochs are related to the particular state. The dy… 相似文献
13.
传统动力学法的观测方程以6个初始轨道参数和先验力模型为初值进行线性化,其线性化误差随积分弧长拉长而增大.本文直接以重力卫星的几何观测轨道为初值进行线性化,其线性化误差与轨道弧长无关,且不需要初始重力场模型和初始轨道参数.导出了基于卫星轨道观测值反演重力场模型的相关公式,利用JPL公布的RL02版本2008年全年的GRACE双星轨道数据和加速度计数据解算了90阶次的地球重力场模型TJGRACE01S,并以EGM2008模型为基准与其他模型进行了比较分析,结果表明:TJGRACE01S模型直到90阶次的大地水准面累积误差为17.6 cm,优于同阶次的EIGEN-CHAMP03S和EIGEN-CHAMP05S模型,前27阶位系数整体精度优于EIGEN-GRACE01S,前15阶位系数整体精度与EIGEN-GRACE02S模型精度大致相当.利用美国8221个GPS水准点数据的分析结果也表明,本文模型也优于同阶次的EIGEN-CHAMP03S和EIGEN-CHAMP05S模型. 相似文献
14.
内编队系统通过构造内卫星纯引力轨道完成高精度重力场测量,实现了不依赖于加速度计的重力卫星实施新途径.针对内编队系统轨道参数和载荷指标设计任务,从定性的角度分析了轨道高度、轨道倾角、偏心率等轨道参数的选择原则,以及外卫星定轨精度、内外卫星相对状态测量精度、内卫星非引力干扰抑制精度、系统采样率等载荷指标对内编队重力场测量性能的影响,并建立了这些参数之间的匹配关系.为获取内编队系统轨道参数和载荷指标的定量设计结果,给出了内编队重力场测量数据模拟和反演计算方法.结合轨道参数和载荷指标对重力场测量性能的影响及其匹配关系,提出了由解析推导和数值计算相结合的方法,获取重力场最高反演阶数、大地水准面精度、重力异常精度等重力场测量性能与轨道参数、载荷指标之间的解析关系,并给出了该解析关系的具体数学形式.与解析法、半解析法相比,该公式由解析推导和大量数值计算得到,因而考虑的影响因素更加全面,计算结果更加合理,可用于快速准确设计内编队系统轨道参数和载荷指标. 相似文献
15.
黄铁矿型结构的晶体化学 总被引:2,自引:0,他引:2
本文根据特征离子坐标变化的特点,对黄铁矿型结构微变规律性进行了讨论,作了一些规律图,总结出:成分的变化控制着u值的变化,u值的变化影响着晶体结构微变化。u值发生变化,MX6反三方柱的顶面和底面中3轴相向或相背移动,u值增加愈接近正八面体,u值发生变化,X(M3X)三方锥底面的方位不变,但锥顶(X7)和锥体内的(X1)的坐标要变化,它们会沿着锥的中轴线相向或相背移动,形成扁平型的三方锥,最后得出:当 相似文献
16.
17.
卫星轨道预报的一种分析方法 总被引:5,自引:0,他引:5
人造地球卫星的轨道预报是空间环境监测和实时跟踪测量中一个重要环节,由于监测对象众多,要求精度也不太高,通常采用分析法预报.在已有分析法得到t时刻平均根数的基础上给出一种轨道预报方法,由t时刻的平均根数给出该时刻卫星的位置和速度,在此基础上将地球非球形引力摄动的周期项直接用卫星直角坐标的位置和速度分量表示,这样可以避免在计算轨道根数变化的周期项时出现的奇点问题,从而对根数的选择无特殊要求,可适用于各种轨道,简化预报程序和相应的软件,提高预报效率。 相似文献
18.
Lambert problem solution in the hill model of motion 总被引:1,自引:0,他引:1
Alexander Sukhanov Antonio F. Bertachini A. Prado 《Celestial Mechanics and Dynamical Astronomy》2004,90(3-4):331-354
The goal of this paper is obtaining a solution of the Lambert problem in the restricted three-body problem described by the
Hill equations. This solution is based on the use of pre determinate reference orbits of different types giving the first
guess and defining the sought-for transfer type. A mathematical procedure giving the Lambert problem solution is described.
This procedure provides step-by-step transformation of the reference orbit to the sought-for transfer orbit. Numerical examples
of the procedure application to the transfers in the Sun–Earth system are considered. These examples include transfer between
two specified positions in a given time, a periodic orbit design, a halo orbit design, halo-to-halo transfers, LEO-to-halo
transfer, analysis of a family of the halo-to-halo transfer orbits. The proposed method of the Lambert problem solution can
be used for the two-point boundary value problem solution in any model of motion if a set of typical reference orbits can
be found. 相似文献
19.
This paper studies the relative motion of satellite formation flying in arbitrary elliptical orbits with no perturbation.
The trajectories of the leader and follower satellites are projected onto the celestial sphere. These two projections and
celestial equator intersect each other to form a spherical triangle, in which the vertex angles and arc-distances are used
to describe the relative motion equations. This method is entitled the reference orbital element approach. Here the dimensionless
distance is defined as the ratio of the maximal distance between the leader and follower satellites to the semi-major axis
of the leader satellite. In close formations, this dimensionless distance, as well as some vertex angles and arc-distances
of this spherical triangle, and the orbital element differences are small quantities. A series of order-of-magnitude analyses
about these quantities are conducted. Consequently, the relative motion equations are approximated by expansions truncated
to the second order, i.e. square of the dimensionless distance. In order to study the problem of periodicity of relative motion,
the semi-major axis of the follower is expanded as Taylor series around that of the leader, by regarding relative position
and velocity as small quantities. Using this expansion, it is proved that the periodicity condition derived from Lawden’s
equations is equivalent to the condition that the Taylor series of order one is zero. The first-order relative motion equations,
simplified from the second-order ones, possess the same forms as the periodic solutions of Lawden’s equations. It is presented
that the latter are further first-order approximations to the former; and moreover, compared with the latter more suitable
to research spacecraft rendezvous and docking, the former are more suitable to research relative orbit configurations. The
first-order relative motion equations are expanded as trigonometric series with eccentric anomaly as the angle variable. Except
the terms of order one, the trigonometric series’ amplitudes are geometric series, and corresponding phases are constant both
in the radial and in-track directions. When the trajectory of the in-plane relative motion is similar to an ellipse, a method
to seek this ellipse is presented. The advantage of this method is shown by an example. 相似文献
20.
We propose a new formal definition of discovery for a Solar System object. It is based on an objective and mathematically
rigorous algorithm to assess when a set of observations is enough to constitute a discovery. When this definition is satisfied,
in almost all cases the orbit is defined well enough to establish the nature of the object discovered (Main Belt vs. Near
Earth Asteroid, Trans-Neptunian vs. long period comet). The frequency of occurrence of exceptions is estimated by a set of
numerical experiments.
The availability of a non-subjective definition of discovery allows some rules to be adopted for the assignment of discovery
credit with a minimum risk of dispute. Such rules should be fair, encourage good practice by the observers and acknowledge
the contribution of the orbit computers providing the identifications and the orbits, as well as the one of all the contributing
observers. 相似文献