The Mars Oxygen ISRU Experiment (MOXIE) on the Mars 2020 Rover

MOXIE is a prototype of a Mars ISRU system that will produce oxygen from carbon dioxide in the Mars atmosphere at ~1% of the scale anticipated to be needed to provide oxygen for propellant for a Mars Ascent Vehicle (and possibly for breathing) in support of a human Mars mission. A payload on the Mars 2020 Rover, MOXIE will produce up to 20 g/hr of oxygen. MOXIE will investigate the interaction of the ISRU system with the Mars environment, using the system as a test bed to exercise a range of control parameters, probe performance margins, provide diagnostics of health and degradation, and explore technology options. The objective is not just to be able to say ‘it worked,’ but rather to learn how to scale MOXIE to support a human mission. The baseline system for CO2 acquisition and compression utilizes a mechanical scroll pump for compressing Mars atmosphere to about 1 bar. An alternative method using cryogenic freezing of CO2 was investigated but was found to be more complex and less efficient than the scroll compressor. Conversion of CO2 to O2 is achieved by means of solid oxide electrolysis. The constraints of mounting MOXIE on the Mars 2020 Rover (mass, volume, intermittent power availability) impose significant engineering challenges. This paper describes the preliminary design of MOXIE, and discusses how it relates to an eventual full-scale scale Mars ISRU system.