Projects on Space Situational Awareness - Tracking of Space Debris, Collision Avoidance and Removal of Space Debris

地球周围的自然和人造物体（空间碎片）的数量正在迅速增加，从而造成与运行中的卫星发生碰撞的严重危险。因此，所有卫星运营商都有必要拥有工具，使他们能够以足够的精度确定和预测这些物体的物理位置，预测碰撞概率，并设计方案以最佳方式进行避碰机动。与此同时，还必须制定清除空间碎片的被动和主动方法。提出的研究计划的目标是在处理上述问题的卫星动力学领域取得进展。具体而言，将进行下列研究：******(i)将研究空间碎片的轨道-姿态耦合传播。考虑到各种环境和扰动效应，将建立适当的数学模型。利用传播涉及多个时间尺度的事实，将开发有效的计算工具来分析模型。******将调查若干主动和被动清除碎片方法的细节：*** (a)碎片捕获后必须转移到墓地轨道。一个显而易见的方法是用拖船和缆绳将碎片拖到墓地轨道。这个牵引问题的各个方面将被研究，包括如何进行一个低推力轨道转移系绳系统的最佳。*** (b)一种有很大潜力的被动碎片清除方法是在碎片上附加一个电动系绳，使轨道衰减得更快。与这些系统相关的许多动力学和稳定性问题目前还没有得到很好的理解。这些将被调查。*** (c)系留空间操纵器在捕获空间碎片方面具有一些优势。这些系绳机械臂的动力学和控制将被研究。******（三）空间资产定期进行避碰机动，以避免向其飞来的空间碎片。机动涉及许多决策：有多少脉冲，何时启动机动，何时返回原轨道，脱靶距离是多少，等等。这个项目的目标是评估这些决策的后果，并设计出最优的决策。******该研究方案的主要成果之一是培养空间技术领域的高素质人才。预计在5年的时间里，将有1名博士后、6名博士生、6名硕士生和几名本科生与我一起从事与该研究计划相关的各种子项目。******该研究计划不仅将推进空间碎片研究领域的知识，而且将使加拿大航天工业和卫星运营商受益。它也有可能为加拿大国防部的空间态势感知活动作出贡献。

The number of natural and man-made objects (space debris) around the Earth is growing rapidly, thereby posing a serious risk of collision with operational satellites. Hence it has become necessary for all satellite operators to possess tools that will provide them capability to determine and predict physical location of these objects with sufficient accuracy, predict collision probability, and devise schemes to carry out collision avoidance maneuvers in an optimal manner. At the same time, methods to remove space debris, both passive and active, must also be developed. The objective of the proposed research program is to make advances in the satellite dynamics area dealing with the above-mentioned issues. Specifically, the following studies will be conducted:******(i) Coupled orbit-attitude propagation of space debris will be studied. Appropriate mathematical models will be developed considering various environmental and perturbation effects. Efficient computational tools will be developed to analyze the models by exploiting the fact that the propagation involves multiple time scales. ******(ii) Details of several active and passive debris removal methods will be investigated:*** (a) The debris must be transferred to a graveyard orbit after its capture. An obvious method is to tow the debris to the graveyard orbit using a tug and a tether. Various aspects of this towing problem will be studied, including how to carry out a low-thrust orbital transfer of a tethered system optimally. *** (b) One passive debris removal method, that has a lot of potential, involves attaching an electrodynamic tether to the debris to make the orbital decay faster. Many dynamics and stability issues associated with these systems are not well-understood at present. These will be investigated. *** (c) A tethered space manipulator can have some advantages for capturing space debris. Dynamics and control of these tethered manipulators will be studied. ******(iii) Space assets conduct collision avoidance maneuvers regularly to avoid space debris heading towards them. The maneuvers involve many decisions: how many impulses, when to initiate the maneuver, when to return to the original orbit, what is the miss distance, etc. The goal of this project is to evaluate the consequences of these decisions and devise optimal ones. ******One of the key outcomes of the research program is to train highly qualified personnel in the area of space technology. It is estimated that 1 postdoctoral fellow, 6 doctoral students, 6 Master's students, and several undergraduate students will work with me on various sub-projects associated with the research program over the 5- year period. ******The research program will not only advance knowledge in the area of space debris research, but also will benefit Canadian space industry and satellite operators. It also has the potential to contribute to the space situational awareness activities of the Department of National Defence of Canada.