Navigation and Control for Autonomous Spacecraft Proximity Operations with Uncooperative Satellites

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- Importance of On-Orbit Servicing**Today, satellites are being used for many different applications, such as remote sensing, global navigation and scientific research. They also provide provide real-time, worldwide communication, including radio, telephone, internet, and television. In remote regions where landline telecommunication and broadband internet capabilities are limited to non-existent, such as Northern Canada, satellite phones and satellite-based internet connections are the only means of communication. A recent study determined that more than 1,200 satellites will be launched over the next 10 years, and revenues from the manufacture and implementation of these satellites is expected to reach $194 billion. While most will perform without major problems, statistics predict that a small but significant number will experience on-orbit anomalies or failures of various severity, resulting in losses of billions of dollars for governments and private organizations. As demonstrated by numerous studies, servicing damaged or failed satellites while in orbit with servicer spacecraft could achieve substantial savings.**- Technical Challenges**On-orbit servicing requires the servicer spacecraft to perform challenging proximity operations, such as visual inspection and relative motion control for rendezvous and docking. To make these proximity operations feasible, the navigation and control capabilities must be improved over traditional single-satellite missions, which means significantly increased autonomy, and highly accurate relative navigation and trajectory control. These challenges are further complicated in practical situations because, due to mechanical or electrical failures, or fuel depletion, the satellite to be serviced will likely be uncooperative, in the sense that it could be rotating at an unknown angular rate, have no communication capabilities, be of an uncertain shape, or have unknown physical parameters (mass and mass moments of inertia). Moreover, un-modeled orbital perturbations can disturb the relative motion of the spacecraft, thus impacting the capability to perform accurate maneuvers safely. **- Objectives and Proposal**In this context, the main objective of this research is to develop intelligent navigation and control systems enabling autonomous spacecraft proximity operations with uncooperative satellites, thereby advancing on-orbit servicing technologies. Specifically, vision-based relative navigation techniques relying on stereo cameras, to be merged with innovative adaptive control theories, will be proposed. These systems will be experimentally validated at the existing Spacecraft Proximity Operations facility, which consists of two small compressed air-propelled spacecraft platforms that can determine and control their relative motion in a laboratory environment.**- Outcome and Benefits to Canada **The outcome of this research program will be a set of guidelines and tools that enable spacecraft designers to develop the most advanced navigation and control systems for spacecraft in close proximity. The proposed program will lead to increased autonomy, safer operations, faster response times, higher motion control accuracy and enhanced robustness of on-orbit servicing missions. This, in turn, will increase the capabilities of these systems, and make on-orbit servicing of uncooperative satellites feasible. Given the increasing interests in such complex space operations in Canada, this research will place Canadian space organizations at the forefront of these technologies, in this niche of the global space market. As an added benefit, the techniques developed will have application to other aerospace-related problems, including those related to unmanned aerial vehicles.