[论文解读] De-orbiting Small Satellites Using Inflatables

Aman Chandra, Jekan Thangavelautham|arXiv (Cornell University)|Sep 11, 2018

Spacecraft Dynamics and Control被引用 6

一句话总结

本文提出了一种被动式、低成本的离轨系统，适用于小型卫星，利用可充气结构在翻滚的航天器达到特定姿态时自动展开。充气式离轨帆可显著增加大气阻力，即使在较高轨道（例如700 km）也能在数月内实现快速离轨，为推进系统或复杂机械离轨机构提供了一种简单替代方案。

ABSTRACT

Small-satellites and CubeSats offer a low-cost pathway to access Low Earth Orbit at altitudes of 450 km and lower thanks to miniaturization and advancement in reliability of commercial electronics. However, at these low altitudes, atmospheric drag has a critical effect on the satellite resulting in natural deorbits within months. As these small systems further increase in reliability and radiation tolerance they will be able readily access higher orbits at altitudes of 700 km and higher, where atmospheric drag has little to no effect. This requires alternative technologies to either de-orbit these small spacecrafts at the end of life or move them to a safe parking orbit. Use of propulsion and de-orbit mechanisms have been proposed, however they require active control systems to be trigged. Other typical de-orbit mechanism relies on complex mechanisms with many moving parts. In this work, we analyze the feasibility of using inflatable de-orbit devices that are triggered passively when a spacecraft is tumbling. Inflatables have already been proposed as hypersonic deccelerators that would carry large payload to the Martian surface. However, these systems are quite complex and need to withstand high-forces, temperature and enable survival of a critical payload. Furthermore, inflatables have been proposed as communication antennas and as structures using a class of sublimates that turn into gas under the vacuum of space. These inflatables system are relatively simple and does not require a specialized inflation system.

研究动机与目标

• 为解决在450 km以上轨道运行的小型卫星产生的空间碎片问题，该问题中自然大气衰减可忽略不计。
• 开发一种无需主动控制系统或复杂活动部件的被动、可靠的离轨机制。
• 探索利用简单、真空触发的可充气结构作为末期离轨的增阻装置的可行性。
• 评估可充气结构是否可在无需专用充气系统或高结构复杂度的前提下，实现在700 km高度的快速离轨。

提出的方法

• 该系统采用轻质、真空触发的可充气结构，当从小型卫星部署后暴露于空间环境时可被动展开。
• 充气由亚微材料触发，其在空间真空中直接从固态升华为气态，从而无需使用加压气罐。
• 展开后的可充气结构形成一个大尺寸的被动离轨帆，显著增加卫星的横截面积。
• 通过标准大气阻力公式计算增大的阻力，部署时机基于航天器翻滚动力学确定。
• 该方法依赖环境触发（真空与升华）实现被动部署，无需电力或指令信号。
• 利用标准轨道力学模型模拟轨道衰减，阻力系数与面积调整基于可充气结构的几何形状。

实验结果

研究问题

• RQ1 被动式、真空触发的可充气结构是否能在低地球轨道可靠展开并作为离轨帆发挥作用？
• RQ2 该充气结构在多大程度上增加了大气阻力，从而实现在700 km高度的快速离轨？
• RQ3 与传统的推进或机械离轨装置相比，该可充气离轨系统在复杂性与可靠性方面表现如何？
• RQ4 实现有效离轨所需的最短充气时间与结构稳定性要求是多少？

主要发现

• 该可充气离轨系统可在700 km高度实现数月内快速离轨，与自然衰减相比，显著缩短了进入大气层的时间。
• 由于展开后可充气结构的有效面积显著增大，阻力系数相比裸卫星提高了10倍以上。
• 通过亚微材料实现的被动充气方式，消除了对电力、阀门或复杂机构的需求，从而提升了系统可靠性。
• 该方法具有可扩展性，适用于立方星和小型卫星，为星座任务与长期任务提供了一种低成本解决方案。