Is Extraction of Methane, Hydrogen and Oxygen from the Lunar Regolith Economically Feasible?

Abstract

The extraction of oxygen from the lunar regolith is relatively straightforward and has been studied extensively. Extraction of hydrogen is also straightforward, but because the concentration of hydrogen is so low (∼50 ppm), the economics is problematical. However, a process for extracting hydrogen may also extract carbon, which is typically present at the 100 ppm level. A small amount of available oxygen can be extracted in the same process, through the hydrogen or carbon reduction of iron oxide in the regolith. Thus, a combined process is possible in which methane and oxygen are the end products. Methane has advantages over hydrogen in terms of storage and liquefaction energy requirements. We show that the combined hydrogen and carbon content of a given quantity of lunar regolith, if converted to methane and used in a methane/oxygen engine, can lift more payload off of the Moon than a hydrogen/oxygen engine utilizing hydrogen and oxygen extracted from the same amount of regolith. We examine the conditions under which it might become economically feasible to utilize these minor constituents of the lunar regolith. It is concluded that improved excavator, extractor, and power technologies could make the extraction economically feasible. This would open practically any place on the Moon as a source of rocket propellant.