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Brasilsat-A2
Brasilsat A2 was a Brazilian geostationary communication satellite belonging to the Brasilsat family. It was built by Spar Aerospace in partnership with Hughes. For most of its useful life it was located in the orbital position of 70 degrees west longitude and was operated by Star One, a subsidiary company of Embratel. The satellite was based on the platform HS-376 and its life expectancy was 8 years. The same was out of commission in February 2004 and was transferred to the graveyard orbit. 34 dBW for most of the Brazilian territory. History In the 1980s, Brazil needed its own satellites to exempt foreigners. As a result of this effort, the Brazilian company Embratel contracted in August 1982 the Canadian Spar Aerospace, Ltd., in partnership with American Hughes, to build its series of "Brasilsat A" satellites, the series consisted of two satellites, the Brasilsat-A1 and the Brasilsat A2. Built by Spar Aerospace, which received US$ 125 million to build under license from Hugh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ELA-2
ELA-2, short for Ensemble de Lancement Ariane 2 ( French for Ariane Launch Area 2), was a launch pad at the Centre Spatial Guyanais in French Guiana. It was used by Arianespace for two Ariane 3 launches (V17 in 1986, V25 in 1988), the second Ariane 2 launch in 1987 (the 20th Ariane launch), and all 116 Ariane 4 launches between 1988 and 2003. Following the retirement of the Ariane 4 in favour of the Ariane 5, ELA-2 was deactivated. In September 2011 the pad's mobile service tower was demolished using explosives. See also *ELA-1 *ELA-3 ELA-3 (french: Ensemble de Lancement Ariane 3, lit=Ariane Launch Complex 3), is a launch pad and associated facilities at the Centre Spatial Guyanais in French Guiana. ELA-3 is operated by Arianespace as part of the expendable launch system f ... References Guiana Space Centre {{rocketry-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Star One (satellite Operator)
Embratel Star One is a Brazilian communication satellite company. It is a subsidiary of Embratel. History Embratel Star One was created in December 2000, as an arm of Embratel in the area of operation and administration of satellites. Satellite fleet Embratel Star One own a small fleet of satellites. * Star One C1 was launched atop an Ariane 5 ECA rocket at 22:06 UTC on 14 November 2007. This launch had previously been delayed from 9 November 2007 due to a problem with the launch vehicle, and then from 12 November 2007 due to a problem with the launch pad. Star One C1 was built by Alcatel Alenia Space based on a Spacebus 3000 B3 satellite bus. It has 28 C-band transponders, 16 Ku-band transponders and one X-band transponder, and weighed about at launch. * Star One C2, the second spacecraft, was launched at 22:17 UTC on 18 April 2008, also aboard an Ariane 5 ECA. * Star One C3 Star One C3 is a communications satellite operated by Star One, a subsidiary of Embratel. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HS-376
The Boeing 376 (sometimes referred to as the BSS-376, and previously as the HS-376) is a communications satellite bus introduced in 1978 by Hughes Space and Communications Company. It was a spin-stabilized bus that the manufacturer claims was the first standardized platform. Design The satellite bus was designed and manufactured by Hughes. This spin-stabilized platform had two main sections. The spinning section was kept rotating at 50 rpm to maintain attitude, and a despun section was used by the payload to maintain radio coverage. The spinning section included the apogee kick motor, most of the attitude control, the power subsystem and the command and telemetry subsystems. The despun section contained the communications payload, including the antennas and transponders. The stock version had a launch mass of , a mass of after reaching geostationary orbit and an 8 to 10-year design life. When stowed for launch, its dimensions were in height and in diameter. With its sol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telecommunication
Telecommunication is the transmission of information by various types of technologies over wire, radio, optical, or other electromagnetic systems. It has its origin in the desire of humans for communication over a distance greater than that feasible with the human voice, but with a similar scale of expediency; thus, slow systems (such as postal mail) are excluded from the field. The transmission media in telecommunication have evolved through numerous stages of technology, from beacons and other visual signals (such as smoke signals, semaphore telegraphs, signal flags, and optical heliographs), to electrical cable and electromagnetic radiation, including light. Such transmission paths are often divided into communication channels, which afford the advantages of multiplexing multiple concurrent communication sessions. ''Telecommunication'' is often used in its plural form. Other examples of pre-modern long-distance communication included audio messages, such as coded drumb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spacebus
Spacebus is a satellite bus produced at the Cannes Mandelieu Space Center in France by Thales Alenia Space. Spacebuses are typically used for geostationary communications satellites, and seventy-four have been launched since development started in the 1980s. Spacebus was originally produced by Aérospatiale and later passed to Alcatel Alenia Space. In 2006, it was sold to Thales Group as Thales Alenia Space. The first Spacebus satellite, Arabsat-1A, was launched in 1985. Since then, seventy-four have been launched, with one more completed, and six outstanding orders. The launch of the 50th Spacebus satellite, Star One C1, occurred in November 2007.Christian Lardier, « Ariane-5 : un tir de l'industrie européenne – le 50e Spacebus », dans ''Air & Cosmos'', N° 2100, du 16 novembre 2007 It was a Spacebus 3000B3, launched by an Ariane 5 rocket flying from the Guiana Space Centre in Kourou, French Guiana. Several variants have been built: the early Spacebus 100 and Spacebus 300; ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Graveyard Orbit
A graveyard orbit, also called a junk orbit or disposal orbit, is an orbit that lies away from common operational orbits. One significant graveyard orbit is a supersynchronous orbit well beyond geosynchronous orbit. Some satellites are moved into such orbits at the end of their operational life to reduce the probability of colliding with operational spacecraft and generating space debris. Overview A graveyard orbit is used when the change in velocity required to perform a de-orbit maneuver is too large. De-orbiting a geostationary satellite requires a delta-v of about , whereas re-orbiting it to a graveyard orbit only requires about . For satellites in geostationary orbit and geosynchronous orbits, the graveyard orbit is a few hundred kilometers beyond the operational orbit. The transfer to a graveyard orbit beyond geostationary orbit requires the same amount of fuel as a satellite needs for about three months of stationkeeping. It also requires a reliable attitude control d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Revolutions Per Minute
Revolutions per minute (abbreviated rpm, RPM, rev/min, r/min, or with the notation min−1) is a unit of rotational speed or rotational frequency for rotating machines. Standards ISO 80000-3:2019 defines a unit of rotation as the dimensionless unit equal to 1, which it refers to as a revolution, but does not define the revolution as a unit. It defines a unit of rotational frequency equal to s−1. The superseded standard ISO 80000-3:2006 did however state with reference to the unit name 'one', symbol '1', that "The special name revolution, symbol r, for this unit is widely used in specifications on rotating machines." The International System of Units (SI) does not recognize rpm as a unit, and defines the unit of frequency, Hz, as equal to s−1. :\begin 1~&\text &&=& 60~&\text \\ \frac~&\text &&=& 1~&\text \end A corresponding but distinct quantity for describing rotation is angular velocity, for which the SI unit is the ra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrazine
Hydrazine is an inorganic compound with the chemical formula . It is a simple pnictogen hydride, and is a colourless flammable liquid with an ammonia-like odour. Hydrazine is highly toxic unless handled in solution as, for example, hydrazine hydrate (). Hydrazine is mainly used as a foaming agent in preparing polymer foams, but applications also include its uses as a precursor to polymerization catalysts, pharmaceuticals, and agrochemicals, as well as a long-term storable propellant for in-space spacecraft propulsion. Additionally, hydrazine is used in various rocket fuels and to prepare the gas precursors used in air bags. Hydrazine is used within both nuclear and conventional electrical power plant steam cycles as an oxygen scavenger to control concentrations of dissolved oxygen in an effort to reduce corrosion. the world hydrazine hydrate market amounted to $350 million. About two million tons of hydrazine hydrate were used in foam blowing agents in 2015. Hydrazines r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solar Cell
A solar cell, or photovoltaic cell, is an electronic device that converts the energy of light directly into electricity by the photovoltaic effect, which is a physical and chemical phenomenon.Solar Cells chemistryexplained.com It is a form of photoelectric cell, defined as a device whose electrical characteristics, such as , , or resistance, vary when exposed to light. Individual solar cell devices are often the electrical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States Dollar
The United States dollar ( symbol: $; code: USD; also abbreviated US$ or U.S. Dollar, to distinguish it from other dollar-denominated currencies; referred to as the dollar, U.S. dollar, American dollar, or colloquially buck) is the official currency of the United States and several other countries. The Coinage Act of 1792 introduced the U.S. dollar at par with the Spanish silver dollar, divided it into 100 cents, and authorized the minting of coins denominated in dollars and cents. U.S. banknotes are issued in the form of Federal Reserve Notes, popularly called greenbacks due to their predominantly green color. The monetary policy of the United States is conducted by the Federal Reserve System, which acts as the nation's central bank. The U.S. dollar was originally defined under a bimetallic standard of (0.7735 troy ounces) fine silver or, from 1837, fine gold, or $20.67 per troy ounce. The Gold Standard Act of 1900 linked the dollar solely to gold. From 1934, it ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brasilsat-A1
Brasilsat A1 was a Brazilian communications satellite which was operated by Embratel. It was constructed by the Spar Aerospace, and is based on the HS-376 satellite bus. The Brasilsat A1 was off duty in March 2002 and was transferred to the graveyard orbit. Specifications The satellite had the shape of a cylinder, where at its top was located a directional antenna that opened after the launching of the satellite. The satellite had a mass in orbit of 671 kg, had a rotation stabilized between 50 and 55 rpm, its propellers used as a propellant 136 kg of hydrazine and was powered by solar cells that supplied 982 Watts at the beginning of its phase of operation, using two NiCd batteries as power reserve. It carried 24 C-band transmitters with six spare transmitters. They provided an effective incident radiated power (EIRP) of 34 dBW for most of the Brazilian territory. * Lead contractor: Spar Aerospace * Model used: HS-376 * Mass at launch: 1,195 kg * Mass ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Communication
Communication (from la, communicare, meaning "to share" or "to be in relation with") is usually defined as the transmission of information. The term may also refer to the message communicated through such transmissions or the field of inquiry studying them. There are many disagreements about its precise definition. John Peters argues that the difficulty of defining communication emerges from the fact that communication is both a Universality (philosophy), universal phenomenon and a Communication studies, specific discipline of institutional academic study. One definitional strategy involves limiting what can be included in the category of communication (for example, requiring a "conscious intent" to persuade). By this logic, one possible definition of communication is the act of developing Semantics, meaning among Subject (philosophy), entities or Organization, groups through the use of sufficiently mutually understood signs, symbols, and Semiosis, semiotic conventions. An im ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
