The concept of plasma-based gas conversion on Mars is an intriguing prospect for in-situ resource utilisation (ISRU) [1-3]. Oxygen and carbon monoxide gas streams can be produced by disassociating carbon dioxide from the Martian ambient for life support and fuel. In this study, we propose to interrogate a novel prototype solid-state microwave (MW) plasma reactor for Martian in-situ gas conversion. Along with CO2 conversion to O2 and CO, the potential of plasma-based Nitrogen fixation (key for enabling Martian farming [4]) will be interrogated for the first time by oxidation of the Nitrogen content (2-3 %) available in the Martian ambient. MW plasmas allow for the generation of plasma conditions that can exploit highly energy-efficient CO2 conversion pathways via vibrational excitation which lowers the effective dissociation energy. This is particularly prominent under the low pressures available on Mars [5]. Vibrational excitation of the Nitrogen fraction in the Martian atmosphere can also significantly lower the threshold for breaking the extremely stable nitrogen triple bond (9.8 eV) which can then be oxidised by oxygen formed from the co-conversion of carbon dioxide. The unique properties of the surface wave sustained MW plasma mode [6, 7] will be exploited for the first time in a Martian context. This plasma mode can operate over a wide range of power and pressure conditions and when coupled with a swirling gas flow ensures the plasma does not interact or erode its containment vessel. MW plasmas in this configuration offer great flexibility which enables direct coupling to intermittent renewable electricity sources such as Martian harvested solar energy (i.e., without energy storage). In order to address the challenge of separating CO/O2/NOx streams in the plasma exhaust mixture, downstream couplings and hybrid approaches will be considered. This will include exploration of gas compression & liquefication technologies, solid oxide electrolysis, and solvent stages.
