Hydroterra was selected in September 2018 as one of the three candidates for the ESA's Earth Explorer-10 mission. Hydroterra aims at observing and improving the understanding of fundamental processes of daily water cycle, enhancing prediction capability of extreme rainfall and related flooding. To achieve this goal, the mission concept envisages placing a satellite embarking a synthetic aperture radar instrument in geosynchronous orbit. The satellite is designed to be launched with VEGA-C into low Earth orbit and to be transferred to the operational orbit by means of electric propulsion. In this paper, the multidisciplinary optimization process carried out to obtain the baseline electric orbit raising transfer for Hydroterra will be presented. The computed trajectory will meet the mission requirements, including targeting to the operational orbit, the launcher performance model, and the target on-station mass. Additionally, system-level constraints related to the satellite design that have an influence on the ideally optimized trajectory will be derived and considered in the optimization. In particular, the impact of the solar cell degradation on the thrust and specific impulse levels of the thruster due to the passage through the Van-Allen belts, the need to re-charge the batteries before entering the next eclipse, and the agility requirements will be accounted for. The obtained results show that a feasible electric orbit raising trajectory can be successfully obtained for the Hydroterra mission.

Hydroterra 于 2018 年 9 月被选为欧空局 Earth Explorer-10 任务的三个候选者之一。Hydroterra旨在观察和提高对日常水循环基本过程的理解，提高极端降雨和相关洪水的预测能力。为实现这一目标，任务概念设想将搭载合成孔径雷达仪器的卫星置于地球同步轨道上。该卫星设计用于与 VEGA-C 一起发射到近地轨道，并通过电力推进转移到运行轨道。在本文中，将介绍为获得 Hydroterra 基线电轨道提升转移而进行的多学科优化过程。计算出的轨迹将满足任务要求，包括瞄准运行轨道、发射器性能模型和目标在站质量。此外，与卫星设计相关的系统级约束对理想优化轨迹有影响，并将在优化中得到考虑。特别是太阳能电池退化对推进器的推力和比冲水平的影响，由于穿过范艾伦带，需要在进入下一次日食之前给电池充电，以及敏捷性要求将予以考虑。所得结果表明，Hydroterra任务可以成功获得可行的电动升轨轨迹。与卫星设计相关的系统级约束对理想优化轨迹有影响，并在优化中加以考虑。特别是太阳能电池退化对推进器的推力和比冲水平的影响，由于穿过范艾伦带，需要在进入下一次日食之前给电池充电，以及敏捷性要求将予以考虑。所得结果表明，Hydroterra任务可以成功获得可行的电动升轨轨迹。与卫星设计相关的系统级约束对理想优化轨迹有影响，并在优化中加以考虑。特别是太阳能电池退化对推进器的推力和比冲水平的影响，由于穿过范艾伦带，需要在进入下一次日食之前给电池充电，以及敏捷性要求将予以考虑。所得结果表明，Hydroterra任务可以成功获得可行的电动升轨轨迹。在进入下一次日食之前需要给电池充电，并且将考虑敏捷性要求。所得结果表明，Hydroterra任务可以成功获得可行的电动升轨轨迹。在进入下一次日食之前需要给电池充电，并且将考虑敏捷性要求。所得结果表明，Hydroterra任务可以成功获得可行的电动升轨轨迹。