Orbits are categorized by altitude, inclination and eccentricity. The altitude determines the area covered by a satellite higher altitude satellites cover a larger region. Inclination influences the minimum maximum latitude covered on the Earth. The two extremes of orbital inclination are an equatorial orbit, which has an inclination of 0*, and a polar orbit, which has an inclination of 90'. A low Earth equatorial orbit would cover a belt around the equator, whereas a polar orbit would cover a belt around the pole orthogonal to the equator, thus covering the full Earth due to the Earth's west east motion beneath. Eccentricity of an orbit determines the shape of the orbit. Satellites in a circular orbit provide an unbiased global coverage, whereas satellites in elliptical orbit favour coverage in specific areas by dwelling on them for a longer time. Examples of low altitude polar constellations are the Iridium and Globalstar systems; the ICO system represents a medium Earth inclined orbit system; the Inmarsat system deploys a GEO; the Ellipso system uses a combination of circular and elliptical orbits, with the higher and mid latitudes covered by the Sun synchronous elliptical orbit and the equatorial region by a circular orbit
