The Earth orbital environment

The first artificial satellite, Sputnik 1, was launched by the USSR on 4 October 1957 in a low elliptical orbit and re-entered into the atmosphere after about 3 months. Since then the exploitation of the space around the Earth lead to an over-crowding of the Earth orbit, producing somehow an environmental problem. Many different orbital regimes have been explored and used since the Sputnik launch, from the very low orbits up to the geostationary orbit, hypothesized many years prior by the famous science fiction writer, Arthur G. Clarke, among others. In Section 2 the main characteristics of the objects currently orbiting the Earth will be described (see also Synthetic Aperture Radar). In Section 3 the different regions of near Earth space will be analyzed in detail, pointing out the main perturbations influencing the motion of a spacecraft in those regimes.