HERMES is a scientific mission composed of 3U nanosatellites dedicated to the detection and localization of high-energy astrophysical transients, with a distributed space architecture to form a constellation in Earth orbits. The space segment hosts novel miniaturized detectors to probe the x-ray temporal emission of bright events, such as gamma-ray bursts, and the electromagnetic counterparts of gravitational wave events, playing a crucial role in future multimessenger astrophysics. During operations, at least three instruments separated by a minimum distance shall observe a common area of the sky to perform a triangulation of the observed event. An effective detection by the nanosatellite payload is achieved by guaranteeing a beneficial orbital and pointing configuration of the constellation. The design has to cope with the limitations imposed by small space systems, such as the lack of on-board propulsion and the reduced systems budgets. We describe the methodologies and the proposed strategies to overcome the mission limitations, while achieving a satisfactory constellation visibility of the sky throughout the mission duration. The mission design makes use of a high-fidelity orbit propagator, combined with an innovative mission analysis tool that estimates the scientific performances of the constellation. The influence of the natural relative motion, which is crucial to achieve an effective constellation configuration without on-board orbit control, is assessed. The presented methodology can be easily extended to any kind of distributed scientific space applications, as well as to constellations dedicated to Earth and planetary observation. In addition, the visibility tool is applicable in the context of the constellation flight dynamics operations, yielding optimized results and pointing plans based on actual satellite orbital positions.

中文翻译：

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HERMES星座中天体数据返回最大化的天空可见性分析

HERMES是一项由3U纳米卫星组成的科学任务，致力于检测和定位高能天体物理瞬变，并采用分布式空间架构来形成地球轨道上的星座。该空间部分装有新颖的小型探测器，以探测亮事件（例如伽马射线暴）的X射线时间发射以及重力波事件的电磁对应物，在未来的多信使天体物理学中发挥关键作用。在操作过程中，至少三台以最小距离隔开的仪器应观察天空的公共区域，以对观察到的事件进行三角测量。通过保证星座的有益轨道和指向配置，可以实现纳米卫星有效载荷的有效检测。该设计必须应对小型空间系统所施加的限制，例如缺少机载推进系统和减少的系统预算。我们描述了克服任务局限性的方法和建议的策略，同时在整个任务持续时间内获得令人满意的星座可见性。任务设计利用高保真轨道传播器，结合创新的任务分析工具来估算星座的科学性能。评估了自然相对运动的影响，这对于在没有机载轨道控制的情况下实现有效的星座构型至关重要。所提出的方法可以轻松扩展到任何种类的分布式科学空间应用，以及专门用于地球和行星观测的星座。此外，可见性工具适用于星座飞行动力学操作，可根据实际卫星轨道位置产生优化结果和指向计划。