The European Space Agency projected the shift from Geosynchronous satellites to medium and low earth orbit satellite constellations. This will drive large changes in the technologies that are used as well as the numbers of satellites. There will be new business models and changes to the economics of the satellite business. There is a shift from satellites for television to satellites for high bandwidth data communication. O3b and others have medium earth orbit (MEO) satellites. They are located at about 8000-kilometer altitude. They deliver low latency fiber-like connectivity to any area approximately 45 degrees north and south of the equator. The orbital·periods of MEO satellites range from about 2 to 24 hours. Low Earth Orbit (LEO) is typically a circular orbit about 400 to 900 kilometers above the earth’s surface. These satellites are only visible from within a small area (about 1000 km radius) beneath the satellite as it passes overhead. Low earth orbit satellites change their position relative to the ground position quickly. A large number of satellites are needed if the mission requires uninterrupted connectivity. Low earth orbiting satellites are less expensive to launch into orbit than geostationary satellites and, due to proximity to the ground, do not require as high a signal strength. They can appear to move as fast as a high-flying jet airliner and sometimes take about four to five minutes to cross the sky.
SOURCES – European Space Agency Written by Brian Wang