Steady-State and Transient Thermal Modeling of Solid Electrolysis (SOXE) within the Mars Oxygen In-Situ Resource Utilization Experiment

Abstract

Humankind has always felt the need to understand our place in the universe. The most direct next step for humankind to accomplish the colossal task of understanding and exploring our place in the solar system is to send people to Mars. This ambitious task requires improved understanding and performance of in-situ resource utilization on Mars’ surface as humans prepare to visit Mars. The Mars Perseverance Rover, which landed on the Martian surface on 18 February, 2021, contained the Mars Oxygen In-Situ Resource Utilization Experiment (MOXIE) as an experimental payload to demonstrate the capabilities of in-situ resource utilization by producing oxygen (O2) out of the abundant carbon dioxide (CO2) that makes up a majority of the Martian atmosphere.

Accurate and high fidelity modelling of internal temperatures of the Solid Oxide Electrolysis (SOXE) stack are crucial to understanding operational performance of MOXIE. Weight, energy, space, and complexity constraints limited the ability to add internal temperature sensors to the flight instrument MOXIE. Tests are being conducted on the Martian surface with limited sensor data available to understand the degradation and performance of the SOXE stack in various operational conditions. A high fidelity model has been created utilizing COMSOL to understand the thermal impact of ambient conditions and empirical data on any given location of the SOXE stack, both internal to the flow path and external. This transient model was validated against data from JPL’s MOXIE testbed laboratory and continued model validation as new data is down-linked from the MOXIE flight model aboard NASA’s Perseverance Rover.

This thesis gives an overview of the thermal system and corresponding thermal and multi-physics modelling of MOXIE. Since MOXIE is an experimental instrument that is confined to the Martian surface with limited sensors, the accurate modelling of detailed thermal data can provide an insight to the instrument’s performance. Similarly, analytical experiments can be conducted utilizing the multi-physics model to predict the results of a warm-up routine and an oxygen-producing run prior to experimenting in the harsh and unforgivable Martian atmosphere. The model will contribute to understanding the performance and thermal response of creating oxygen on the Martian surface to aid in human exploration.