PhD Oral Exam - Jason Gerard, Computer Science

When studying for a doctoral degree (PhD), candidates submit a thesis that provides a critical review of the current state of knowledge of the thesis subject as well as the student’s own contributions to the subject. The distinguishing criterion of doctoral graduate research is a significant and original contribution to knowledge.

Once accepted, the candidate presents the thesis orally. This oral exam is open to the public.

Abstract

Space exploration and near-Earth observability missions are generating increasing volumes of scientific data that exceed the capacity of today’s radio-frequency infrastructure. Free-space optical (FSO) communication offers orders-of-magnitude higher data rates, especially for deep-space communication. However, the narrow beamwidth requires pointing, acquisition, and tracking (PAT) to align optical terminals before data transmission can begin, a process that can take several minutes for interplanetary links, which reduces capacity. Link uptime is further impacted because terminals may spend a significant portion of each contact window establishing the link rather than transmitting data. Space networks schedule links based on contact plans that define the time-varying network topology. Contact plan design (CPD) is a temporally coupled graph-theoretic decision problem where edges are selected and sequenced. However, existing CPD approaches do not account for the impact of PAT delay on link scheduling, leading to overestimated capacity. This thesis develops a retargeting-aware CPD framework that integrates PAT delay and temporal max-flow capacity modeling into mixed-integer linear programming (MILP) and heuristic algorithms to compute retargeting-aware contact schedules. Using realistic orbital and communication models, the proposed approach achieves over 30% higher backhaul capacity in both interplanetary and near-Earth scenarios compared to methods that neglect PAT delay. The results reveal a shift in optimal scheduling behavior, where fewer but longer-duration contacts are preferred, while delay-unaware models produce fragmented schedules. These findings establish a foundation for retargeting-aware CPD and demonstrate that optical terminal dynamics must be incorporated to enable optical backhaul for the Solar System Internet and near-Earth missions.