航天器环绕小行星Ivar的运动分析

将小行星Ivar近似为三轴椭球体，给出了非球形引力势函数，建立了航天器环绕小行星Ivar的轨道动力学方程。利用Jacobi积分常数绘制了航天器在Ivar周围的零速度曲线，并分析了航天器的可能运动区域，给出了航天器不碰撞小行星Ivar的边界条件及不同偏心率下的近拱点半径。分析了小行星Ivar扁率和椭率对环绕轨道的影响，数学仿真结果表明：在一个轨道周期内，顺行轨道的开普勒能量、轨道角动量、偏心率和近拱点半径变化较大，而逆行轨道的相应参数变化较小。

Motion analysis of spacecraft around the asteroid Ivar

The asteroid Ivar is modeled as a tri-axial ellipsoid,its sphere gravitational potential is given,and spacecraft orbital dynamics equation around the asteroid Ivar is established.According to integral Jacobi constant,the spacecraft zero-velocity curves in the vicinity of asteroid is described and feasible motion regime is analyzed.Limited condition and periapsis radius corresponding to difference eccentricity against impact surface of the asteroid Ivar is presented.Effect of asteroid oblateness and ellipticity to orbital stability is analyzed.The math simulation indicate that orbit energy,angular momentum,periapsis radii and eccentricity of direct orbit experience much large changes in a orbit periods.by contraries,correspond parameter of retrograde orbits changes little.