Bowne, Madeline M has requested to schedule their PhD Thesis Final Examination (Defense). This request has been approved by their faculty advisor, the AE Associate Chair for Graduate Programs, and the AE Communications Office. Please proceed to post the annoucement on the OGE website. The details are as follows:

Student Name: Madeline Bowne

Advisor: Dr. Dimitri Mavris

Milestone: PhD Thesis Final Examination (Defense)

Degree Program: Aerospace Engineering

Title: Flexible Space Junk Allocation & Waste Abatement (Space JAWA): Flexibility Framework To Screen Strategies & Options For Sustainable On-Orbit Servicing Infrastructures In LEO

Abstract: As mega-constellations proliferate in Low Earth Orbit (LEO), the rate of satellite re-entry is accelerating dramatically. Since January 2023, over 1,420 objects have re-entered Earth's atmosphere, with this rate expected to increase substantially over the next decade. While de-orbiting satellites mitigates orbital congestion, the environmental consequences of atmospheric re-entry remain uncertain, potentially impacting the ozone layer and climate. Transitioning from single-use satellites to a circular space economy through On-Orbit Servicing (OOS) could address these concerns by making space operations more sustainable. Despite OOS success in Geosynchronous Orbit, LEO-based servicing remains economically challenging due to low launch costs and inefficient orbital maneuvering. Existing flexibility frameworks for OOS, while valuable for understanding customer demand, lack comprehensive treatment of multi-domain uncertainty, combinatorial flexible options, and novel concepts such as temporary orbital storage. This thesis makes three distinct contributions to address these gaps. First, it introduces Collection-as-a-Service (CAAS), a novel concept for circular space economies in LEO that enables satellite collection, refurbishment, and redeployment. Second, it develops a comprehensive flexibility framework that considers both satellite constellation and servicing infrastructure perspectives, modeling evolving on-orbit servicing space logistics through Monte Carlo scenarios with decision rules. Third, it integrates quantitative policy analysis into the flexibility framework, modeling various policy schemes within the discrete event simulation to assess their impact on total cost, NOx emission reduction, refurbishment rates, and OOS viability. Through discrete event simulation and object-oriented programming, the framework models interactions between satellite constellations and servicing infrastructure across uncertain futures, incorporating multiple uncertain variables including launch costs, manufacturing costs, and customer revenue. Results demonstrate that specific architectural configurations achieve sustainability improvements while maintaining cost parity with traditional approaches. Configurations featuring one pre-initialized depot warehouse with rendezvous and proximity operations-capable satellites and flexible serviceability upgrades provide the best balance of cost and emission reductions. Key enablers include dual-mission launch architectures for warehouse resupply and Earth-based refurbishment capabilities. The framework reveals that moderate policy interventions, such as a $50,000 Orbital Use Fee that forms a superfund and enables rebates for satellite collections, can achieve cost neutrality while reducing operational risk and improving refurbishment throughput. Critically, no single element independently guarantees success across all metrics; rather, integrated consideration of technical configurations, flexible deployment strategies, and policy interventions is essential. These findings validate that the proposed flexibility framework is effective for identifying context-dependent strategies that balance economic viability, environmental sustainability, and operational resilience, providing policymakers and industry stakeholders with viable pathways toward circular space economies. 

Date and time: 2025-11-07, 11:00am

Location: Collaborative Visualization Environment (CoVE) Weber SST II

Committee:
Dr. Dimitri Mavris (advisor), School of Aerospace Engineering
Dr. Koki Ho, School of Aerospace Engineering
Dr. Mariel Borowitz, Sam Nunn School of International Affairs
Dr. Mark Whorton, NASA Marshall Space Flight Center & School of Aerospace Engineering
Dr. Olivia Fischer, School of Aerospace Engineering
Dr. Tristan Sarton du Jonchay, School of Aerospace Engineering