脉冲星在空间飞行器定位中的应用

Positioning for a Spacecraft using Pulsars

利用脉冲星钟模型能高精度地预报脉冲星脉冲到达太阳系质心的时间。基于脉冲星时、空参考架可实现各类空间飞行器的自主导航。讨论了脉冲星钟的模型和脉冲星导航系统的框架结构,描述了脉冲星导航的基本原理和算法。指出脉冲星导航系统对脉冲星脉冲到达探测器时刻的测量精度,是决定空间飞行器位置解算精度的关键因素。脉冲星导航观测采用的原子钟如果足够稳定,则空间飞行器位置的解算方法可以简化。在脉冲星导航系统计时观测精度达到或优于几十微秒量级时,脉冲星视差、相对论效应的影响是不可忽略的。对脉冲星导航系统开发设计中的关键技术和进一步研究的主要问题进行了初步分析和讨论。

Pulsars offer most reliable timing standard due to their very stable rotation.Their celestial positions in space was determined.So pulsars can be used as both time standard and spatial reference coordinates.It is very important to investigate navigation for a spacecraft using pulsar timing information.Earth-based navigation of deepspace satellites has satisfactory navigational accuracy only along the line-of-sight.During Solar conjunctions no precision navigation is possible.Autonomous navigation for a spacecraft may be realized by using pulsars.Such a navigation system offers three dimension coordinates of spacecraft with respect to the barycenter of solar system.Radio pulsars can be used only for navigation of spacecraft with heavier payload and X ray pulsar navigation system is suitable for most popular spacecraft.The model of pulsar clock is discussed and a frame structure of pulsar navigation system is outlined.The algorism of spacecraft position is referenced to the Ariadna study by Sala J,Urruela A,Villares X.Today about 1 800 radio pulsars and 70 X ray pulsars are known.For the most of them rotational parameters（rotational frequency and its derivatives）and astrometry parameters（positions and proper motions）was determined.Modeled pulsar clock can predict rotational phase with respect to the barycenter of solar system.Measured phase delay on spacecraft relative to predicted value with respect to the barycenter of Solar system contains information on spacecraft position.Timing observations on spacecraft of a group of pulsars well distributed on the sky may offer positions of spacecraft by a good algorism.The positioning accuracy of spacecraft is mainly determined by timing ability on spacecraft which depends on performance of detectors to pulsar radiation. Shapiro and Einstein delay and parallax effect should be considered while high precision timing is carried out on spacecraft.Some key technology and method in developing such a navigation system is addressed and discussed.