Ph.D. Defense
Karl Roush
(Advisor: Prof. Dimitri Mavris)
"Adapting the Past for Future Flight: Preliminary Design Framework for
Long Duration O&S Aerospace Programs:
On
Friday, November 1
11:00 a.m.
Collaborative Design Environment (CoVE)
Weber Space Science and Technology Building (SST II)
and
Join the meeting now
Abstract
Aerospace programs face significant challenges due to their immense scale, extended timelines, and substantial budgets. While the reuse of heritage technologies helps reduce costs and mitigate risks, it introduces complications as these elements often struggle to meet modern requirements. This incompatibility, coupled with increasingly lengthy post-design phases, leads to substantial operations and support (O&S) challenges.
While certainly a known issue, these constraints have been documented as worsening in GAO reports, OIG investigations, RAND studies, Congressional Reports, and more. These challenges have taken a priority role in programs’ considerations as evidenced by the command media updates across NASA, the DOD, and commercial entities.
Past efforts to tackle this issue exist, but they often lack applicability to the unique aerospace context, particularly regarding long-term O&S considerations. Attempts at modeling the supply base are confined to broad characterizations and lack the means to communicate disruptive rare events- which are more likely to occur as O&S duration increases.
This research addresses three key gaps in the field: O&S best practices are ill-suited for heritage technology reuse, the shallow and dynamic aerospace supply base in modeling approaches is not captured, and communication of rare events over an extended O&S phase is lacking.
Correspondingly, the research delivers three main contributions. First, it identifies shortfalls in existing producibility best practices and revises them for heritage technology reuse through a comprehensive case study of the Space Shuttle Program. Second, it enhances supply base modeling by implementing a distributional approach to learning rates and associated cost projections, validated using NASA's standard PCEC tool and a novel retrospective LCC estimate for the Space Shuttle. Third, it integrates concepts from portfolio management and extreme value theory to create a toolkit for evaluating rare events in the context of cost estimates and O&S considerations.
The legacy of the Space Shuttle continues today with the Space Launch System (SLS) containing many heritage elements and an expectedly long O&S duration, in line with the major themes of this work. Applying the contributions of this work to the SLS program revealed improved adherence to the modified best practices, potential substantial underestimation in NASA's public cost projections, and reduced likelihood of extreme cost outliers for SLS relative to the Shuttle program.
In today's fiscally cautious space environment, the challenge lies in strategically leveraging prior resources while considering financial realities over long O&S horizons. The efforts of this research work aim not only to ensure the long-term viability of projects like SLS under this dual mandate, but also to contribute to broader efforts in planning the next generation of space exploration programs. It provides actionable guidance and valuable tools for immediate use by designers, planners, cost estimators, and engineers, paving the way for the next era of human spaceflight.
Committee
- Prof. Dimitri Mavris – School of Aerospace Engineering (advisor)
- Prof. Brian Gunter – School of Aerospace Engineering
- Prof. Daniel Schrage– School of Aerospace Engineering
- Dr. Elena Garcia – School of Aerospace Engineering
- Claude Russell (Russ) Joyner II – Aerojet Rocketdyne/An L3Harris Technologies Company