Methods for Co-Orbital Threat Assessment in Space

Sammanfattning: This study investigates methods for assessing threats in space. Space services are crucial to both civilian and military capabilities, and a loss of such systems could have severe consequences. Space systems are exposed to various types of threats. To ensure the benefits of space-based applications, protect space assets, improve security, and maintain the space environment, it is crucial to assess threats in space. This thesis focuses on co-orbital antagonistic threats arising from satellites that are capable of performing precision manoeuvres. These satellites could either perform physical attacks or perform operations such as inspection, eavesdropping, or disruption on other satellites. Lambert's problem can be utilised for calculating orbital transfers. By solving the problem iteratively over a range of values of when the transfer is executed and the transfer time, it is possible to detect when a transfer is feasible. This can be used to assess when a satellite can pose a threat to a target. The calculations of orbital transfers are improved by the implementation of a genetic algorithm. The algorithm can solve for both direct transfers to the target and transfers using multiple impulses. Furthermore, a genetic algorithm, called NSGA-II, which can handle multiple objective functions is also analysed. The implemented methods show the potential of being employed to assess threats, especially for direct transfers where a single impulse is executed to transfer to a target. In this case, it is possible to identify threats based on the satellite's $\Delta v$ budget. However, when additional impulses are introduced it becomes more complicated. It is more difficult to estimate when an attack is more likely to commence. The implemented methods show potential, but further research is required in order to develop a robust method to assess co-orbital threats.  The conducted analysis has highlighted a few aspects that are crucial for assessing co-orbital threats. Information about the $\Delta v$ budget of the satellite that potentially could pose a threat must be available. Furthermore, space surveillance and tracking capabilities are essential to detect orbital changes, which can be vital to perform counter-operations in the event of an attack