Electronic Subsystem Modeling in Radiation Environments Using the SEAM Platform

Abstract

Spaceborne systems are continuously exposed to harsh radiation environments, including total ionizing dose (TID) effects, single-event effects (SEEs), and transient disruptions. These radiation-induced phenomena can significantly compromise the functionality, reliability, and safety of critical subsystems. As systems become increasingly integrated and component-level testing grows more difficult and costly, developing effective assurance strategies is essential to mitigate these risks. Mathematically-based simulation platforms, such as SPICE and TCAD, often require detailed physical parameters and material properties that may not be readily available from device manufacturing companies, particularly for complex subsystems incorporating commercial off-the-shelf (COTS) components or legacy modules. This poses challenges for accurately modeling radiation effects in systems whose internal design details are not fully accessible, such as star trackers. To address these challenges, this thesis investigates subsystem-level modeling in radiation environments using the Systems Engineering and Assurance Modeling (SEAM) platform. SEAM provides a structured, qualitative approach to building system models, functional models, Goal Structuring Notation (GSN) models, and fault trees. It enables systematic analysis of radiation vulnerabilities and the development of mitigation strategies. Operating at a high level of abstraction compared to mathematically based low-level tools, SEAM supports fault propagation analysis and vulnerability prediction even with limited design data. Two case studies demonstrate the methodology: a temperature control subsystem in a CubeSat’s Command and Data Handling (CDH) board and critical electronic modules from the PyCubed satellite platform, including its microprocessor and modular radio. Through detailed subsystem modeling, fault analysis, and assurance case construction, this work illustrates how SEAM can help engineers identify failure modes and improve radiation tolerance. In addition, the thesis introduces structural and functional modeling approaches that capture both physical architecture and operational logic. A Key Performance Indicator (KPI)-based method is also proposed to guide fault modeling, especially in cases involving complex and extensive subsystem documentation. These methods demonstrate SEAM’s capability to support early-stage modeling and assurance case development for spaceborne subsystems under radiation exposure.