地火中继链路的空间特征参量分析

针对火星和地球上合时导致的直接通信链路中断问题,提出基于日地拉格朗日点L₄/L₅为中继的地火中继架构. 建立日心黄道惯性坐标系下L₄/L₅到火星的指向矢量在不同空间参考坐标系下变换的数学模型,推导了L₄/L₅指向火星的空间特征参量(空间距离、方位角和俯仰角)随星体瞬时平轨道根数变化的解析式. 仿真验证了一个地火回归年内的空间特征参量的变化规律,设计了一种L₄/L₅对火星表面的链路持续可见模型,并分析了返向链路性能. 为L₄/L₅指向火星的星间链路设计提供了参考. 

Analysis of Spatial Characteristic Parameter of Relay Link Between Earth and Mars

For the interruption of directcommunications with Mars duringsuperior conjunction, relay architecture based on the Sun-Earth Lagrange point L₄/L₅ for the relay to Mars was proposed. The mathematical model of the pointing vector from L₄/L₅ to Mars under the heliocentric ecliptic inertial coordinate was established at different spatial reference coordinates system transformation. The analytical expression of spatial characteristic parameter which was L₄/L₅ pointing to Mars along with the instantaneous orbital elements of celestial body was deduced. Simulation experiment shows the variation of spatial characteristic parameter in one tropical year between Earth and Mars. One sustained connection model which was viewed from L₄/L₅ to Mars surfaces was designed and the performance of the return link was analyzed. It provides a reference for the design of inter-satellite link of L₄/L₅ pointing to Mars.