Mars colonies, at least, can rely on Nitrogen and CO2 from the Martian atmosphere. Orbital habitats have to import everything but sunlight.
Having the colonies underground may have an extra advantage, both on Mars and on the Moon, as they may be closer to sources of ice. I remember hearing something about the Moon being much less dry than previously thought. No running water nor blocks of ice, but maybe crunching rocks yields something useful.
Having the colonies underground may have an extra advantage, both on Mars and on the Moon, as they may be closer to sources of ice. I remember hearing something about the Moon being much less dry than previously thought. No running water nor blocks of ice, but maybe crunching rocks yields something useful.