Addressing the Mars ISRU Challenge: Production of Oxygen and Fuel from CO_2 using Sunlight

Abstract

Advanced exploration of Mars, particularly human missions, will require vast amounts of fuel and oxygen for extended campaigns and the return of samples or humans back to Earth. If fuel and oxygen can be prepared on Mars from in-situ resources, this would greatly reduce the launch mass of the mission from Earth. In this Keck Institute for Space Sciences (KISS) study, the viability of Mars near-ambient temperature photoelectrochemical (PEC) or electrochemical (EC) production of fuel and oxygen from atmospheric carbon dioxide—with or without available water—was examined. With PEC devices incorporated into lightweight, large-area structures operating near 25°C and collecting solar energy to directly convert carbon dioxide into oxygen, it may be possible to reduce the launch mass (compared with bringing oxygen directly from Earth) by a factor of three or more. There are other numerous benefits of such a system relative to other in-situ resource utilization (ISRU) schemes, notably reduced thermal management (e.g., lower heating demand and decreased amplitude of thermal cycling) and the elimination of a need for a fission power source. However, there are considerable technical hurdles that must be surmounted before a PEC or EC ISRU system could be competitive with other more mature ISRU approaches, such as solid oxide electrolysis (SOXE) technology. Noteworthy challenges include: the identification of highly stable homogeneous or heterogeneous catalysts for oxygen evolution and carbon monoxide or methane evolution; quantification of long-term operation under the harsh Martian conditions; and appropriate coupled catalyst–light absorber systems that can be reliably stowed then deployed over large areas, among other challenges described herein. This report includes recommendations for future work to assess the viability of and advance the state-of-the-art for EC and PEC technologies for future ISRU applications. Importantly, the challenges of mining, transporting, purifying, and delivering water from Mars resources to a PEC or EC reactor system, development and demonstration of a low-temperature-capable, non-aqueous-based CO2 reduction scheme as described below is perhaps the first logical step toward implementing an efficient near-surface Mars temperature oxygen generation system on Mars.

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