Baseline trajectory design for solar polar detection using gravity assists

Abstract

Solar polar detection can greatly enrich human understanding of the solar magnetic field. However, accurate polar flybys are rarely involved in previous trajectory designs due to the requirement of an enormous amount of velocity. This paper identifies gravity assist trajectories for solar polar detection missions in patched-conic models. An analysis model is proposed to judge whether a gravity assist sequence can achieve a required excess velocity (v∞) at the planet encounter for the solar polar flyby. In addition to the classical Jupiter gravity assist trajectory, some less conventional paths, such as Jupiter–Earth (JEnGA), Jupiter–Venus (JVnGA), and Venus–Earth–Venus (Vn1En2Vn3GA), are examined. These unconventional trajectories can reach final short-period orbits. For JEnGA and JVnGA trajectories, two different cases are found: in the transfer process, case 1 has a shorter perihelion, and case 2 has a higher inclination. In Vn1En2Vn3GA trajectory, the aphelion distance can be reduced from 5.2 AU to 3.7 AU compared with those trajectories mainly using Jupiter gravity assist. The final orbital periods vary from 83 days to 4.1 years in the trajectories provided, and the corresponding transfer times are from 46 years to 1.2 years. In the future, designers of practical missions can choose the appropriate trajectory according to their specific needs.