Based on the XRD analysis of lunar soil samples, ilmenite as a regolith component has been shown to be a prime candidate for In-Situ Resource Utilization (ISRU) on the Moon. ISRU involves the use of local resources to support human activities, reducing the need to transport materials from Earth. The processing of ilmenite into titanium, iron, and oxygen could significantly enhance the sustainability and cost-effectiveness of lunar missions. The required energy consumption for the reduction of ilmenite with hydrogen has been estimated. It has been shown that the use of a 20 kW solar power plant operating on the basis of existing technologies and materials can supply oxygen to a three-person lunar mission. Analysis of XRD patterns of Martian soil obtained by the Curiosity mission directly on Mars has revealed that the ilmenite content is insufficient to be used as a source of titanium. Aluminium-rich minerals of the plagioclase group are the most likely source of producing construction aluminium using an extremely energy-consuming electrolysis method.