A geosynchronous orbit is an Earth-centered orbit with an orbital period that matches Earth's rotation on its axis, 23 hours, 56 minutes, and 4 seconds. The synchronization of rotation and orbital period means that, for an observer on Earth's surface, an object in geosynchronous orbit returns to exactly the same position in the sky after a period of one sidereal day. Over the course of a day, the object's position in the sky may remain still or trace out a path, typically in a figure-8 form, whose precise characteristics depend on the orbit's inclination and eccentricity. A circular geosynchronous orbit has a constant altitude of 35,786 km (22,236 mi).
A geostationary orbit, also referred to as a geosynchronous equatorial orbit (GEO), is a circular geosynchronous orbit 35,786 km (22,236 mi) in altitude above Earth's equator, 42,164 km (26,199 mi) in radius from Earth's center, and following the direction of Earth's rotation.
A communications satellite is an artificial satellite that relays and amplifies radio telecommunication signals via a transponder; it creates a communication channel between a source transmitter and a receiver at different locations on Earth. Communications satellites are used for television, telephone, radio, internet, and military applications. Many communications satellites are in geostationary orbit 22,236 miles (35,785 km) above the equator, so that the satellite appears stationary at the same point in the sky; therefore the satellite dish antennas of ground stations can be aimed permanently at that spot and do not have to move to track the satellite. Others form satellite constellations in low Earth orbit, where antennas on the ground have to follow the position of the satellites and switch between satellites frequently.
Syncom started as a 1961 NASA program for active geosynchronous communication satellites, all of which were developed and manufactured by the Space and Communications division of Hughes Aircraft Company. Syncom 2, launched in 1963, was the world's first geosynchronous communications satellite. Syncom 3, launched in 1964, was the world's first geostationary satellite.
A very-small-aperture terminal (VSAT) is a two-way satellite ground station with a dish antenna that is smaller than 3.8 meters. The majority of VSAT antennas range from 75 cm to 1.2 m. Bit rates, in most cases, range from 4 kbit/s up to 16 Mbit/s. VSATs access satellites in geosynchronous orbit or geostationary orbit to relay data from small remote Earth stations (terminals) to other terminals or master Earth station "hubs".
Satellite Internet access is Internet access provided through communication satellites; if it can sustain high speeds, it is termed satellite broadband. Modern consumer grade satellite Internet service is typically provided to individual users through geostationary satellites that can offer relatively high data speeds, with newer satellites using the Ku band to achieve downstream data speeds up to 506 Mbit/s. In addition, new satellite internet constellations are being developed in low-earth orbit to enable low-latency internet access from space.
Westar 1 was America's first domestic and commercially launched geostationary communications satellite, launched by Western Union (WU) and NASA on April 13, 1974. It was built by Hughes for Western Union, using the HS-333 platform of spin-stabilized satellites. It operated until May 1983.
The PBS Satellite Service consists of feeds relayed from PBS by satellite to public television stations throughout the United States. The service was launched in September 1978. The service provides a mixed variety of programming selected from PBS's regular network services. In the X/XP years a satellite feed was multicast by some PBS member stations on an over-the-air DTV subchannel along with their regular programming, or during overnight hours on their main channel to provide a second opportunity for viewers to watch or record primetime programming.
Pendrell Corporation is an intellectual property (IP) investment, advisory services and asset management firm. The company develops and implements strategies to acquire, commercialize, manage, divest and license IP. The company, formerly ICO Global Communications, is based in Kirkland, Washington.
Thuraya is a United Arab Emirates-based regional mobile-satellite service (MSS) provider. The company operates two geosynchronous satellites and provides telecommunications coverage in more than 161 countries in Europe, the Middle East, North, Central and East Africa, Asia and Australia. Thuraya's L-band network delivers voice and data services.
Satcom, a portmanteau of satellite communications, was a brand of artificial geo-stationary communications satellites originally developed and operated by RCA American Communications that facilitated wide-area telecommunications by receiving radio signals from Earth, amplifying them, and relaying them back down to terrestrial receivers.
A tracking and data relay satellite (TDRS) is a type of communications satellite that forms part of the Tracking and Data Relay Satellite System (TDRSS) used by NASA and other United States government agencies for communications to and from independent "User Platforms" such as satellites, balloons, aircraft, the International Space Station, and remote bases like the Amundsen-Scott South Pole Station. This system was designed to replace an existing worldwide network of ground stations that had supported all of NASA's crewed flight missions and uncrewed satellites in low-Earth orbits. The primary system design goal was to increase the amount of time that these spacecraft were in communication with the ground and improve the amount of data that could be transferred. These TDRSS satellites are all designed and built to be launched to and function in geosynchronous orbit, 35,786 km (22,236 mi) above the surface of the Earth.
Satellite television is a service that delivers television programming to viewers by relaying it from a communications satellite orbiting the Earth directly to the viewer's location. The signals are received via an outdoor parabolic antenna commonly referred to as a satellite dish and a low-noise block downconverter.
A geosynchronous satellite is a satellite in geosynchronous orbit, with an orbital period the same as the Earth's rotation period. Such a satellite returns to the same position in the sky after each sidereal day, and over the course of a day traces out a path in the sky that is typically some form of analemma. A special case of geosynchronous satellite is the geostationary satellite, which has a geostationary orbit – a circular geosynchronous orbit directly above the Earth's equator. Another type of geosynchronous orbit used by satellites is the Tundra elliptical orbit.
The Master Control Facility (MCF) is a facility set up by the Indian Space Research Organisation (ISRO) in the city of Hassan in the Indian state of Karnataka. Established in 1982, this facility is responsible for monitoring and controlling geostationary and geosynchronous satellites launched by ISRO. This was the only Master Control Facility of ISRO till another one was established in Bhopal in 2005.
Galaxy 18 is a Space Systems/Loral (SS/L) 1300-series hybrid communications satellite owned by Intelsat and located in geosynchronous orbit at 123° W longitude, serving the continental United States, Alaska, Hawaii, Mexico, and Canada with 24 C band, and 24 Ku band transponders. Galaxy 18 replaced Galaxy 10R near the end of its design life.
The Intelsat VI series of satellites were the 8th generation of geostationary communications satellites for the Intelsat Corporation. Designed and built by Hughes Aircraft Company (HAC) in 1983-1991, there were five VI-series satellites built: 601, 602, 603, 604, and 605.
Intelsat 603 or IS-603, previously named Intelsat VI F-3, is a communications satellite operated by Intelsat. Launched in 1990, it was the second of five Intelsat VI satellites to be launched. The Intelsat VI series was constructed by Hughes Aircraft, based on the HS-389 satellite bus.
Galaxy 15 is an American telecommunications satellite which is owned by Intelsat. It was launched for and originally operated by PanAmSat, and was subsequently transferred to Intelsat when the two companies merged in 2006. It was originally positioned in geostationary orbit at a longitude of 133° West, from where it was used to provide communication services to North America.
Lincoln Experimental Satellite 4, also known as LES-4, was a communications satellite, the fourth of nine in the Lincoln Experimental Satellite, and the first of the series designed for operations at geosynchronous altitudes. Launched by the United States Air Force (USAF) on 21 December 1965, it demonstrated many then-advanced technologies including active use of the military's SHF band to service hundreds of users.
