Active Removal and Situational Awareness of Space Debris in Low Earth Orbits

过去60年来，人类在太空活动中积累的碎片已成为一个关键问题，特别是在非常商业化的近地轨道（LEO）。人们普遍认为，如果人类要继续可持续地利用近地空间，就必须解决这种情况。这一认识促使人们对减少空间碎片增长和修复空间环境的方法进行深入研究。我建议提高现有解决方案的技术准备水平，促进我们的理解，并开发新的方法来解决这个多方面问题的关键问题。该提案的第一个重点是主动清除碎片。现在有一个广泛的共识，即每年需要清除5到10个大型碎片物体；然而，对于部署这样一项任务的最佳技术，目前还没有达成一致。在我先前关于使用系留网捕获大型空间碎片的研究的基础上，我将通过开发和评估确保碎片封存的网合方法，进一步推进系留网解决方案；通过研究捕获后系统的稳定策略；并通过实验验证了系绳网捕获碎片的概念。对于任务的后续阶段，即由此产生的系绳追尾器-碎片系统的脱离轨道，我建议研究系绳辅助概念——通过系绳摆动和旋转——来制动碎片，使其下降到地球大气层。我的第二个研究重点是碎片环境的空间态势感知。在这个广泛的领域内，我将致力于提高我们对大型空间碎片运动的理解和推进预测能力，重点是它们的旋转运动。这项研究将回答一些基本问题：这些碎片在未来的某个时候会在哪里？它们将如何旋转？由于碎片不受控制地翻滚，它们的姿态对轨道上所经历的扰动力和扭矩（如空气动力阻力和太阳辐射压力）具有时变影响。这些因素反过来又直接影响到碎片的轨道和位置。我们将努力扩大我们对当前扰动效应模型中的不确定性如何影响传播中的不确定性的理解，并制定随机模型来量化这些影响。我们将探索利用观测数据，结合我们的预测模型，制定参数、摄动和碎片姿态运动的估计算法。加拿大是一个航天国家：它发射卫星，加拿大人民依靠我们的太空资产在他们的一生中可靠地运行。鉴于空间碎片对功能性资产构成的威胁，我们必须具备参与未来碎片清除任务的专门知识，以及预测碎片对空间环境影响的知识和工具。

The build-up of debris from human activities in space over the past 60 years has become a critical issue, particularly in the very commercial low Earth orbits (LEO). It is widely accepted that this situation must be addressed if humans are to continue sustainable exploitation of near Earth space. This acknowledgement has spurred intense research on ways to curtail space debris growth, and remediate the space environment. I propose to increase technology readiness levels of existing solutions, to advance our understanding and to develop novel methodologies to address key issues in this multifaceted problem. The first focus of this proposal is on active debris removal. There is now broad consensus on the need to remove five to ten large debris objects per year; yet, there is no agreement on the best technology to deploy for such a mission. Building on my prior research on the use of tethered nets for capture of large space debris, I will further advance the tethered-net solution through the development and evaluation of net closing methods to ensure debris containment; by investigating strategies for system stabilization after capture; and through experimental demonstration of the tethered-net concept for debris capture. For the subsequent phase of the mission, the de-orbiting of the resulting tethered chaser-debris system, I propose to investigate tether-assisted concepts---through tether swinging and spinning---for braking the debris into a descent towards the Earth's atmosphere. My second research focus falls under the umbrella of space situational awareness of the debris environment. Within this broad domain, I will work on improving our understanding and advancing prediction capabilities for the motion of large space debris, with emphasis on their rotational motion. This research will answer the basic questions: where will the debris be at some time in the future and how will it be spinning? Because the debris are tumbling uncontrollably, their attitude has a time-varying effect on the perturbation forces and torques experienced in orbit, such as, the aerodynamic drag and solar radiation pressure. These in turn directly influence the orbit and location of debris. We will work to expand our understanding of how uncertainties in our current models of perturbation effects affect the uncertainties in the propagation and formulate stochastic models to quantify these effects. We will explore the use of observational data, jointly with our predictive models, to formulate estimation algorithms for parameters, perturbations and the attitude motion of the debris. Canada is a space faring nation: it launches satellites and Canadian people depend on our space assets to function reliably over their life-time. Given the threats presented by space debris to functional assets, it is critical that we have expertise to participate in future debris removal missions, as well as, the knowledge and tools to predict the impact of debris on the space environment.