Research On NEO Tracking And Orbit Determination Methods Using Space-based Optical Observation

The program of Near Earth Object(NEO) surveillance is the premise and fundamental part of the planetary defence, and the tracking and orbit determination technology as its key component has been widely concerned by the major space agencies and scholars, thus this technology is one of the most hot research topics in the realm of aerospace science.Compare with the traditional earth-based observation system, due to its superiority in the observational efficiency and sky coverage, the space-based optical observation system has become the important development trend of future NEO observation system.Based on the planetary defence, this dissertation mainly stress on researching NEO tracking and orbit determination methods using the space-based optical measurement. The main works are as follows:Firstly, the NEO tracking and orbit determination model using the space-based optical observation is studied, and then the optical visibility for NEO is analyzed. According to the obtaining methods and characteristics of the space-based optical observation, the corresponding tracking and orbit determination is given. On the foundation, orbit dynamics model of NEO and observation model of optical sensor are established, and the effect of celestial gravity perturbation and solar radiation pressure perturbation is analyzed. And thus the visibility is also analyzed from the aspect of geometric constraints, field of view of observatory, limiting magnitude and light source, etc.Secondly, a method of initial orbit determination(IOD) using space-based optical observation is developed to solve the problem of poor observation geometry and iterative convergence in short-arc IOD. Aiming to reinforce the orbit restraint and improve the convergence, the constraints of heliocentric two-body energy and speed maximum for NEO is introduced. Then the Gauss equation is converted into constrained optimization problem,and a method of IOD based on the sequential quadratic programming(SQP) algorithm is given. On this basis, in order to acquire better precision of IOD, the use of short-term continuous intensive measurement data is considered to improve the observation geometry,and then a method of IOD based on the homotopy algorithm is given, and at the same time the IOD performance is also analyzed.Thirdly, a method of tracking and orbit determination using space-based optical observation is developed to solve the problem of orbit drift in the space-based bearing-onlytracking and orbit determination. On the basis of researching on the observability of the tracking and orbit determination system, a method of tracking and orbit determination based on the square root EKF algorithm for one space-based platform is given, in which space-based optical observation is used and the need of autonomous orbit determination is also considered. Thus, based on this method, a method of joint orbit determination based on the covariance intersection estimation fusion algorithm is given to improve the observability.Finally, taking into account the trend of space-based survey systems and the need of NEO observation, three different solutions of joint orbit determination based on the space-based platform is designed, which include observational site of the geocentric orbit,the moon-based platform, and the Sun-Earth L2 Halo orbit, and then orbit determination performance of these solutions for different types of NEO is analyzed.