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，从而构成了与运行中的卫星发生碰撞的严重危险。因此，所有卫星运营者都必须拥有工具，使其能够足够准确地确定和预测这些物体的实际位置，预测碰撞概率，并制定计划以最佳方式进行避免碰撞的机动操作。与此同时，还必须制定被动和主动清除空间碎片的方法。拟议研究方案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：* ㈠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影响，将建立适当的数学模型。将开发有效的计算工具，利用传播涉及多个时间尺度的事实来分析模型。 **（二）将研究若干主动和被动清除碎片方法的细节：*（a）碎片在被捕获后必须转移到倾弃轨道。一个明显的方法是使用拖船和系绳将碎片拖到墓地轨道。各个方面 包括如何最佳地进行系留系统的小推力轨道转移。* （B）一种很有潜力的被动式碎片清除方法是在碎片上系上电动系链，使轨道衰减得更快。许多动态 并且与这些系统相关的稳定性问题目前还没有得到很好的理解。这些将被调查。* （c）系留空间机械手在捕获空间碎片方面可具有某些优势。这些绳系机械手的动力学和控制将进行研究。 * ㈢空间资产定期进行避免碰撞机动，以避免空间碎片撞向它们。机动涉及许多决定：多少冲动，何时启动机动，何时返回到原来的轨道，什么是脱靶距离等，这个项目的目标是评估这些决定的后果，并制定最佳的。 ** 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。据估计，1名博士后研究员，6名博士生，6名硕士生和几名本科生将在5年内与我一起从事与研究计划相关的各种子项目。 ** 该研究方案不仅将增进空间碎片研究领域的知识，而且还将使加拿大航天工业和卫星运营商受益。它还有可能促进加拿大国防部的空间态势认知活动。

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.