Lunar and martian materials can be processed and used at planetary outposts to reduce the need (and thus the cost) of transporting supplies from Earth. A variety of uses for indigenous, on-site materials have been suggested, including uses as rocket propellants, construction materials, and life support materials. Utilization of on-site resources will supplement Regenerative Life Support Systems (RLSS) that will be needed to regenerate air, water, and wastes, and to produce food (e.g., plants) for human consumption during long-duration space missions. Natural materials on the Moon and/or Mars may be used for a variety of RLSS needs, including (i) soils or solid-support substrate for plant growth, (ii) sources for extraction of essential plant-growth nutrients, (iii) sources of O2, H2, CO2, and water, (iv) substrates for microbial populations in the degradation of wastes, and (v) shielding materials surrounding outpost structures to protect humans, plants, and microorganisms from radiation. In addition to the regolith, the martian atmosphere will provide additional resources at a Mars outpost, including water, CO2, and other atmospheric gases.