【作者】 魏二虎；

【导师】 刘经南； 李征航；

【作者基本信息】 武汉大学 ， 大地测量学与测量工程， 2006， 博士

【摘要】 空间甚长基线干涉测量技术SVLBI(Space Very Long Baseline Interferometry)是地面VLBI测量在空间的延伸。它在大地测量和地球动力学方面很有应用潜力,如不同参考框架的定义、实现和相互连接,利用延迟和延迟速率来进行VLBI测站地心坐标的测定,地球重力场的估计和卫星定轨等。随着1997年日本的VSOP(the VLBI Space Observatory Programme)卫星的发射(Hirabayashi等,1998),这一技术变成了现实。在匈牙利卫星大地天文台(F?MI SGO)的资助下,一个国际的研发小组针对SVLBI在大地测量应用的可行性进行了VSOP大地测量实验(GEDEX)(Kulkarni等,1998)。该国际科研小组采用地面和空间VLBI(VSOP)的延迟和延迟率等实际观测量,对于大地测量和地球动力学的几个方面进行了研究。结果表明,由于VSOP项目是为了天体物理研究而设计的,其物理特性和轨道特征并不完全适用于大地测量和地球动力学研究和应用。后者要求卫星有较规则的外形、较小的面质比和较长的寿命,其定轨精度应达到与观测精度相当的水平(好于几cm)。而VSOP的外形极不规则,面质比较大,寿命估计只有5年,其定轨精度的实验估计值为几米(Frey2002),很难达到10cm的水平。VSOP还不适合于频繁改变观测对象,所以无法提供针对多个射电源的观测量,而这正是大地测量和地球动力学所需要的。况且,该卫星从2003年10月后就没有能够继续发送观测数据,在2005年11月30日02:28UT终止了运作。因此需要新的空间VLBI卫星来支持大地测量和地球动力学的研究。目前还没有专门设计适合于大地测量和地球动力学研究的空间VLBI卫星的研究,为此,本文总结了大地测量和天体测量研究对空间VLBI卫星的要求条件。GEDEX实验结果表明定轨精度是限制VSOP用于大地测量研究的主要障碍之一。因此,本文研究了可以对空间VLBI卫星精密定轨的几种技术和应用的可能性。根据卫星轨道的分类、大地测量和天体测量对空间VLBI卫星的要求,以及GNSS(GPS和GALILEO)卫星对空间VLBI卫星跟踪观测的几何条件而设计了我国空间VLBI卫星的六个轨道根数。研究了我国卫星测控网的现状,并开发了测控网对不同高度空间覆盖分析的程序;采用此程序仿真设计了测控不同高度地球卫星的测控网。以及采用此程序,设计了我国空间VLBI卫星的遥控跟踪网,研究了此网对我国空间VLBI卫星的跟踪效率,给出了分析结果。研究了全球SLR网络对我国空间VLBI卫星的跟踪观测效率,给出了分析结果。研究了我国空间VLBI卫星与地面VLBI网络联合观测射电源的观测量数量统计、分辨率大小和对射电源u-v图像覆盖的效果,给出了研究结果。研究了我国空间VLBI卫星轨道的摄动模型,给出了计算的摄动量级和应该考虑的摄动项。对于设计的空间VLBI卫星轨道还需要进一步研究来说明该轨道中的空间VLBI系统在确定天体测量和大地测量参数时的精度水平和研究该卫星能否对大地测量和地球动力学的潜在应用进行了改进。为此,我们针对已经分析的可估计性大地测量参数和利用对可估计参数推导出简化模型(Kulkarni 1992)。研究了空间VLBI观测量对一些主要的系统影响包括大气折射、太阳光压和相对论效应的灵敏度。模拟地面-空间的时间延迟观测量,进行了平差计算的模拟研究。模拟研究结果表明设计的卫星轨道中的我国空间VLBI将可以确定大地测量和地球动力学感兴趣的参数,而且比更多还原

【Abstract】 The unique radio astronomical technique of Space Very Long Baseline Interferometry (SVLBI) is an extension of the ground-based VLBI into the space. It has some important potential applications in geodesy and geodynamics, including the definition, practical realization, and the interconnection of different reference frames, determining the geocentric positions of VLBI stations, estimation of the gravity field of the Earth, and satellite orbit determination using the delay and delay rate observables. With the launching of the first SVLBI satellite of the VLBI Space Observatory Program (VSOP) of Japan, in February 1997, this technique has become a reality. An international team of scientists, working under the auspices of the F?MI Satellite Geodesy Observatory, Hungary, has designed the GEDEX, for the purpose of exploring the feasibility of the geodetic applications of SVLBI. However, several major problems also exist. As a result, the current realization of SVLBI cannot be considered as an‘extension’to the traditional ground-based geodetic VLBI, as was often assumed in the early studies (Fejes et al. 1996, and references therein). In other words, although the space baselines are indeed added to the interferometer network, on the other hand, some crucial features are missing because the VSOP mission is designed for astrophysical (radio imaging) purposes. It is not suitable for geodetic and geodynamic study, which requires a regular shape, small area-to-mass ratio, precise tracking capabilities resulting in cm orbit accuracy, negligible slew times and long operational life (10-15 years). But the shape of VSOP satellite is quite irregular, with a large a/m and a short operational life (5 years). The orbit determination of HALCA is accurate to 2-5 m (Frey 2002), and it is quite difficult to be accurate to 10 cm. Also, VSOP cannot frequently change observing object, hence it cannot supply more observations to many quasars, which are required for geodesy and geodynamics. Besides, VSOP terminated operation on Nov. 30, 2005. Hence, a new space VLBI satellite is needed to support geodetic and geodynamic study.At present, there is no dedicated research thesis on the design of geodetic and geodynamic space VLBI, hence this investigation studies and summarizes the geodetic requirements of space VLBI satellite. The result of GEDEX indicates that the orbit determination precision of space VLBI satellite is one of the main problems for geodetic study, therefore this investigation studies several technologies which possibly will be able to determine the orbit of space VLBI satellite. And then, according to the kind of satellite and the requirements for geodetic and astrometric study and the geometry of GNSS (GPS, GALILEO) satellite to track the space VLBI satellite, the six Keplerian elements of Chinese space VLBI satellite (TEST-SVLBI) are selected and determined. According to the space and deep space detection plan of China, the realization of Chinese satellite surveying and control network are studied. A program is designed to analyze the coverage area of the space of different heights by the stations of the network, with更多还原