Satellite constellation (original) (raw)
A group of electronic satellites working in concert is known as a satellite constellation. Such a constellation can be considered to be a number of satellites with coordinated coverage, operating together under shared control, synchronised so that they reinforce rather than interefere with one another.
Low Earth orbiting satellites (LEOs) are often deployed in satellite constellations, especially since they must travel at a higher angular velocity to maintain their orbit. This makes them unsuitable for geostationary use due to orbital decay and frequently being unable to be "seen" over the horizon in various places, therefore requiring multiple satellites to maintain consistent coverage.
Examples of satellite constellations include the Global Positioning System (GPS) and GLONASS constellations for navigation and geodesy, the Iridium and Globalstar satellite telephony services, Russian elliptical-orbit Molnya constellations, and the proposed Teledesic broadband constellation. These applications require low-delay communications, and therefore must orbit nearer the Earth, making such constellations a necessity.
Satellite constellation coverage and geometry � determining the minimumnumber of satellites needed to provide a service, and their orbits � is a field in itself.