行星三体引力摄动对卫星探测器大气制动的影响

考虑行星引力在其卫星探测器大气制动过程中的显著摄动，建立了基于Milankovitch参数的平均轨道动力学模型并对土卫六探测器进行仿真。首先，将轨道参数转换为无奇异的Milankovitch参数，考虑探测卫星的大气阻力、扁率摄动以及行星引力摄动，建立了半解析轨道方程。其次，以土卫六探测器为对象，选择不同的土星初始方位角进行有大气和无大气情况下的数值仿真，并进行比较分析。结果表明，土星初始方位角的选择会引起土卫六大气制动轨道偏心率和近拱点高度在不同范围内震荡，极大地影响大气制动效果。 

Effect of planet's third-body gravitational perturbation on aerobraking of moon's explorer

An averaged orbital dynamics model for a natural satellite aerobraking was established and an Titan explorer was simulated to study the notable planet's third-body gravitational perturbation during the process.Firstly,non-singular Milankovitch elements were introduced to represent the orbital motion.A semi-analytical orbital equation was obtained considering moon's atmospheric drag, oblateness perturbation, and planet's gravitational perturbation.Secondly, taking Titan explorer as an example, simulations and analysis were carried out with different azimuth choices between Saturn and apse line when atmospheric drag was exclu-ded and included.The results show that different initial azimuth of Saturn with respect to the apsidal line would cause that eccentricity and periapsis height oscillate in different intervals, which will ultimately influ-ence the aerobraking result.