The Extraterrestrial Metals Processing (EMP) system produces ferrosilicon, silicon monoxide, a glassy mixed oxide slag, and smaller amounts of alkali earth compounds, phosphorus, sulfur, and halogens from Mars, Moon, and asteroid regolith by carbothermal reduction. These materials, in some cases after further processing with other in-situ resources, are used for production of high-purity iron and magnesium metals (for structural applications), high purity silicon (for photovoltaics and semiconductors), high purity silica (for clear glass), refractory ceramics (for insulation, thermal processing consumables, and construction materials), and fertilizer (from phosphorus recovered from carbothermal reduction exhaust gases). Carbothermal reduction also co-produces oxygen at yields on the order of 20 percent of regolith feed mass when integrating downstream processes to recover and recycle carbon. Many of the EMP products can be prepared in a fashion suitable for casting or additive manufacture methods and have broad application in support of advanced human space exploration. The EMP methods are based on minimal reliance on Earth-based consumables; nearly all of the gases and reagents required for processing can be manufactured from Mars in-situ resources or can be recovered and recycled for applications using Moon or asteroid resources.