In-situ thermite combustion of micro magnesium fuel and lunar regolith simulant nanoparticles

Abstract

Significant heat generation will be required for humans and equipment to the lunar night. In this work, we investigate the use of a sustainable in-situ thermite material as a fuel to provide the thermal energy required to keep components in working conditions. Magnesium is used as a reactive metal fuel, with lunar regolith simulant ball milled to sub-micron sizes as a solid oxidizer producing exothermic reactions. Enhanced combustion is achieved by controlling particle size and composition of the thermite mixture. Simulant particles ranging from hundreds of nanometers to tens of microns in diameter are tested, as well as the magnesium fuel compositions of 20% to 40% by weight. Small pellets of 3 mm in diameter and 3 mm in height are ignited by laser in both air and vacuum to quantify the combustion properties in different environments. High speed video, infrared camera and pyrometry techniques are taken to quantify the sample combustion properties. These pellets demonstrate the burning rates between 2.3 and 5.9 mm/s and temperatures ranging from 1100 to 1480 °C in vacuum and in air conditions, respectively. The samples composed of 20% magnesium and 80% regolith simulant release around 400 J/g, and sustain elevated temperatures for 15 s after combustion, making them suitable for in-situ lunar heating. Novel 2D temperature mapping allows greater understanding of the simulant thermite combustion. Based on the results, we discuss the design considerations that would need to be made in the creation of an in-situ metal fuel heating lunar system.