Student Name: Seungyeop Han

Advisor: Dr. Koki Ho

Milestone: PhD Thesis Proposal

Degree Program: Aerospace Engineering

Title: Resilient Design and Management of LEO Satellite Constellations

Abstract: Satellite failures reduce the coverage and service capacity of low Earth orbit (LEO) constellations. This dissertation develops mathematical models and solution methods for resilient constellation design and management by combining operations research with orbital mechanics. The goal is to support early-stage architecture decisions through the evaluation of cost, service performance, and operational feasibility. The first part addresses regional constellation design that incorporates in-plane spares for failure recovery and accounts for launch costs. Candidate orbital slots are constructed using a Walker-Delta arrangement, and the design problem is formulated as a mixed-integer linear program (MILP). For large candidate sets, the greedy randomized adaptive search procedure (GRASP) identifies promising orbital planes, and a reduced MILP determines the final constellation. The second part addresses spare replenishment for large-scale constellations. It compares launches to individual orbital planes with replenishment architectures that use J2-driven nodal precession to reduce launch costs. Markov chain models combined with inventory control enable rapid analysis of stochastic failures, spare availability, and replenishment delays. The resulting cost and service-performance measures support the optimization of replenishment policies and architectures under specified performance requirements. The third part addresses on-orbit servicing for expensive satellites with repairable failures. Uncertain failures are represented through service-demand rates, and queueing models determine the required servicing capacity. A J2-aware transfer model captures the trade-off between maneuver cost and service duration. These models are incorporated into a MILP to determine depot locations, servicer numbers, and demand allocation. Time aggregation and a revised rolling-horizon method reduce the computational scale. Planned work will address servicing and fuel-replenishment decisions through queue-based dispatch.

Date and time: 2026-10-29, 9:30 AM - 11:30 AM

Location: Coda C1015 Vinings

Committee:
Dr. Koki Ho (advisor), School of Aerospace Engineering
Dr. Brian C. Gunter, School of Aerospace Engineering
Dr. Edgar Glenn Lightsey, School of Aerospace Engineering
, 
, 
,