For an actual planetary settlement, distinguish ordinary physical dimensions from theoretical extra dimensions. Dimension or parameter What to calculate Why it matters 3 spatial dimensions Length, width, height Planet shape and surface structures 1 time dimension Day, year, timekeeping Climate cycles and operations Mass and radius Gravity and escape velocity Orbital geometry Orbit, eccentricity and inclination Rotation Angular velocity Day length and rotational effects Atmosphere Pressure and composition Breathing, climate and radiation shielding Water system Accessible liquid water or ice Drinking, agriculture and industry Energy system Power generation and storage Life support and manufacturing Magnetic environment Field strength and particle exposure Radiation-risk assessment Extra dimensions Model-dependent geometry Theoretical research; no known habitability requirement A habitable planet does not need additional spatial dimensions under established science. Our current models of ...