Ground Station based Point Ahead Angle Derivation & Variability for Spacecraft in Highly Elliptical Orbits

This study focuses on the mathematical derivation and variations of the Point Ahead Angle (PAA) from ground stations for spacecraft operating in highly elliptical orbits (HEO's), that are in most of the cases geostationary transfer orbits (GTO's). The Point Ahead Angle is a critical parameter for maintaining communication links between ground stations and spacecraft, particularly in orbits with significant eccentricity. Through detailed mathematical analysis, this research derives the complex formulas required to compute the Point Ahead Angle for spacecraft traversing highly elliptical orbits. By conducting comprehensive simulations, we analyse the dependencies of the Point Ahead Angle on orbital eccentricity, station locations, and communication techniques especially free space optical communication. This paper presents precise formulas for calculating the Point Ahead Angle for HEO's and evaluates its variability under different orbital and spacecraft's velocity conditions. By offering a thorough understanding of Point Ahead Angle derivation and its variability, this research contributes to the enhancement of communication systems for spacecraft in highly elliptical GTO's, facilitating efficient data transmission and mission success.