Overview of the in-situ oxygen production technology for lunar resources

The rich resources and unique environment of moon position it as the prime candidate for human development and the utilization of extraterrestrial resources. Oxygen plays a vital role in supporting human life on the moon, with lunar regolith serving as a highly oxygen-rich polymetallic oxide that can be processed using existing metallurgical techniques to extract oxygen and metals. Furthermore, the ample reserves of water ice on the moon offer an additional avenue for oxygen production. This paper offers a detailed overview of the leading technologies poised to achieve in-situ oxygen production on the moon, drawing from an analysis of lunar resources and environmental conditions. It delves into the principles, processes, advantages, and drawbacks of water ice electrolysis, two-step oxygen production from lunar regolith, and one-step oxygen production from lunar regolith. The two-step methods involve hydrogen reduction, carbothermal reduction, and hydrometallurgy, while the one-step methods encompass fluorination/chlorination, high-temperature decomposition, molten salt electrolysis, and molten regolith electrolysis (MOE). Following a thorough comparison considering raw materials, equipment, technology, and economic viability, MOE emerges as the most promising approach for future lunar in-situ oxygen production. Considering the high-temperature corrosion characteristics of molten lunar regolith, as well as the environmental characteristics of low gravity on the moon, the development of inexpensive and stable inert anodes and the development of electrolysis devices that can easily collect oxygen are considered key breakthroughs in promoting MOE technology on the moon. This review holds substantial theoretical importance in enhancing our understanding of lunar in-situ oxygen production technology and the forthcoming lunar exploration initiatives.