This paper presents the trajectory design for EQUilibriUm Lunar-Earth point 6U Spacecraft (EQUULEUS), which aims to demonstrate orbit control capability of CubeSats in the cislunar space. The mission plans to observe the far side of the Moon from an Earth-Moon L2 (EML2) libration point orbit. The EQUULEUS trajectory design needs to react to uncertainties of mission design parameters such as the launch conditions, errors, and thrust levels. The main challenge is to quickly design science orbits at EML2 and low-energy transfers from the post-deployment trajectory to the science orbits within the CubeSat’s limited propulsion capabilities. To overcome this challenge, we develop a systematic trajectory design approach that 1) designs over 13,000 EML2 quasi-halo orbits in a full-ephemeris model with a statistical stationkeeping cost evaluation, and 2) identifies families of low-energy transfers to the science orbits using lunar flybys and solar perturbations. The approach is successfully applied for the trajectory design of EQUULEUS.

中文翻译：

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EQUULEUS弹道设计

本文介绍了EQUilibriUm登月点6U航天器（EQUULEUS）的轨迹设计，旨在证明立方卫星在顺月空间中的轨道控制能力。该任务计划从月球L2（EML2）解放点轨道观察月球的另一侧。EQUULEUS的弹道设计需要对任务设计参数的不确定性做出反应，例如发射条件，误差和推力水平。主要挑战在于如何在EML2上快速设计科学轨道，以及如何在CubeSat有限的推进能力范围内从部署后的轨迹向科学轨道进行低能转移。为克服这一挑战，我们开发了一种系统的轨迹设计方法，该方法包括：1）在一个完整的星历模型中设计超过13,000个EML2准晕轨道，并进行统计维护成本评估，和2）利用月球飞越和太阳摄动来识别低能向科学轨道转移的族。该方法已成功应用于EQUULEUS的轨迹设计。