Date of Award

6-2024

Document Type

Thesis

Degree Name

Doctor of Philosophy (PhD)

Department

Department of Aeronautics and Astronautics

First Advisor

Andrew S. Keys, PhD

Abstract

The US Space Force (USSF) is currently investigating possible opportunities to improve the testing paradigm of spacecraft in order to get assets on-orbit faster, while maintaining suitable quality to meet mission needs in a contested space environment. To support this goal, USSF’s approach to test and evaluation (T&E) is centered around the concept of integrated test. In this research, the space text lexicon is defined, addressing the ambiguities on exactly what integrated test is with respect to spacecraft systems development and on-orbit mission assurance. This research considered any statistical trends in categorical discrepancies (i.e., anomalies) during prelaunch integration and test (I&T) between past and present data, as well as any identified interconnected anomalies. Additionally, anomaly trends in operational on-orbit data were statistically analyzed in the same manner as pre-launch anomalies in order to identify any correlations between prelaunch tests and operational space vehicle reliability. The main correlation was that the thermal vacuum test was a predictor of the frequency of anomalies a spacecraft payload would experience while on orbit. Correlations were also made demonstrating the effects of sequential missions reduce frequency of discrepancies and increase the robustness of a spacecraft’s performance. This informed the development of a novel statistical function called the Spacecraft Survivability Index (SSI), characterizing space vehicle reliability through accounting for the assessed reliability of individual subsystems/components, together with the number and characteristics of component/system testing both performed and not performed.

These analyses will be used in the future to refine the SSI and use the SSI to model space vehicle I&T activities in order to assess how adjusting the I&T flow (through truncation, omission, etc.) affect space vehicle reliability. This research is intended to provide a quantitative means to demonstrate how the spacecraft I&T flow can be optimized for mission needs. This research will help determine impacts of practices, which will in turn be used to suggest and support Lean integrated spacecraft testing policy to the Test and Evaluation office at Headquarters USSF (USSF/TE), which reports directly to the Vice Chief of Space Operations. This is critical to the integrated test concept because it will clearly integrate the effects of pre-launch testing with on-orbit operations, enabling the collaborative planning between the contractor, Systems Program Office (SPO), testers, and operations teams, as well as a clear means to share data and independently evaluate system survivability. This work recommends the extensive use of government-held architectures to streamline flow of communication and data, as well as ensure integration between test events, including those as the NSTTC, all the while suggesting preference be made towards spacecraft that are commoditized and/or mature in design, as well as qualified in design.

AFIT Designator

AFIT-ENY-DS-24-J-037

Comments

A 12-month embargo was observed for posting this work on AFIT Scholar.

Distribution Statement A, Approved for Public Release. PA case number on file.

Related organizations and units for this Masters thesis:

  • Center for Space Research and Assurance (CSRA) at AFIT
  • Space Systems Command, U.S. Space Force (USSF/SSC)

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