<P> GOCE orbited at about 255 km and had an aerodynamic shape and ion thrusters to reduce and compensate for atmospheric drag . </P> <P> The mean orbital velocity needed to maintain a stable low Earth orbit is about 7.8 km / s, but reduces with increased orbital altitude . Calculated for circular orbit of 200 km it is 7.79 km / s and for 1500 km it is 7.12 km / s . The delta - v needed to achieve low Earth orbit starts around 9.4 km / s . Atmospheric and gravity drag associated with launch typically adds 1.3--1.8 km / s to the launch vehicle delta - v required to reach normal LEO orbital velocity of around 7.8 km / s (28,080 km / h). </P> <P> Equatorial low Earth orbits (ELEO) are a subset of LEO . These orbits, with low inclination to the Equator, allow rapid revisit times and have the lowest delta - v requirement (i.e., fuel spend) of any orbit . Orbits with a high inclination angle to the equator are usually called polar orbits . </P> <P> Higher orbits include medium Earth orbit (MEO), sometimes called intermediate circular orbit (ICO), and further above, geostationary orbit (GEO). Orbits higher than low orbit can lead to early failure of electronic components due to intense radiation and charge accumulation . </P>

Gps satellites orbit the earth at what height above its surface