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Amazonas 4A
The Amazonas 4A, renamed in 2016 Amazonas 4 and since 2017 known as the Hispasat 74W-1, is a Spanish commercial communications satellite developed by Orbital Sciences Corporation and operated by Hispasat. It was successfully launched in 2014 and it is expected to have a service life of 15 years however, shortly after its launch the satellite suffered a power failure that limited its operability and life. It is positioned to cover all of South America and during its service life the satellite has offered coverage for some important events such as the 2016 Summer Olympics and World Cup football broadcasts. Body The satellite is based on the GEO Star-2.4 bus and has a dry mass of 1,241 kg. It is shaped like a square-faced prism 5 meters tall. Its lateral faces hold two deployable reflector-antennas and two retracting solar panels that, when fully deployed, give the satellite a diameter nearing 23 meters. At launch, its mass was increased to 2,938 kg. Propulsion The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hispasat
Hispasat is the operating company for a number of Spanish communications satellites that cover the Americas, Europe and North Africa from orbital positions 30.0° West and 61.0° West. It was formed in 1989 and its activities include provision of communication services in the commercial and government sectors (corporate networks, advanced telecommunications services, telephony, videoconferencing, etc.). Hispasat's fleet of satellites broadcast more than 1250 television channels and radio stations to more than 30 million homes, as well as providing services such as broadband to mobile telephones and landlines. The first Hispasat satellite sent into orbit was Hispasat 1A, which was launched on 11 September 1992 on board an Ariane 4 launch vehicle from the Centre Spatial Guyanais near Kourou in French Guiana. It was put into geostationary orbit at 30° West, which is the location of all their subsequent satellites serving Spain and Europe. The Amazonas satellites (61° West) wer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vehicle Weight
Vehicle weight is a measurement of wheeled motor vehicles; either an actual measured weight of the vehicle under defined conditions or a gross weight rating for its weight carrying capacity. Curb or kerb weight Curb weight (U.S. English) or kerb weight (British English) is the total mass of a vehicle with standard equipment and all necessary operating consumables such as motor oil, transmission oil, brake fluid, coolant, air conditioning refrigerant, and sometimes a full tank of fuel, while not loaded with either passengers or cargo. The gross vehicle weight is larger and includes the maximum payload of passengers and cargo. This definition may differ from definitions used by governmental regulatory agencies or other organizations. For example, many European Union manufacturers include the weight of a driver and luggage to follow European Directive 95/48/EC. Organizations may also define curb weight with fixed levels of fuel and other variables to equalize the value for the comp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ariane 5 Mission 21
Ariane may refer to: *Ariana (name), also Ariane, Arianne Arts * ''Ariane'' (Martinů), an opera by Bohuslav Martinů, first performed 1961 * ''Ariane'' (Massenet), an opera by Jules Massenet, first performed 1906 * ''Ariane'' (film), a 1931 German film directed by Paul Czinner * Ariane Films, a former French film production company * ''Ariane'', a play by Thomas Corneille (1625–1709) * ''Ariane'', the name of the 1957 film '' Love in the Afternoon'' in French speaking markets Transportation * Simca Ariane, a French car by Simca, 1957–1963 * Ariane (automobile), a French car by Automobiles Ariane, 1907 * French ship ''Ariane'', the name of several French ships * Ariane (rocket family), European rockets operated by Arianespace Other uses * Ariane (apple), an apple cultivar * 1225 Ariane, an asteroid * Tour Ariane (Ariane Tower), an office building west of Paris See also *Ariadna (other) *Ariadne (other) *Arianna (other) *Ariana (other) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Decibel Watt
The decibel watt (dBW or dBW) is a unit for the measurement of the strength of a signal expressed in decibels relative to one watt. It is used because of its capability to express both very large and very small values of power in a short range of number; e.g., 1 milliwatt = −30 dBW, 1 watt = 0 dBW, 10 watts = 10 dBW, 100 watts = 20 dBW, and 1,000,000 W = 60 dBW. :\mbox = 10 \log_\frac and also :\mbox = 10^ Compare dBW to dBm, which is referenced to one milliwatt (0.001 W). A given dBW value expressed in dBm is always 30 more because 1 watt is 1,000 milliwatts, and a ratio of 1,000 (in power) is 30 dB; e.g., 10 dBm (10 mW) is equal to −20 dBW (0.01 W). In the SI system the non SI modifier decibel (dB) is not permitted for use directly alongside SI units so the dBW is not directly permitted but 10 dBW may be written 10 dB (1 watt). See also *dBm DBM or dbm may refer to: Science and tech ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transponder
In telecommunications, a transponder is a device that, upon receiving a signal, emits a different signal in response. The term is a blend word, blend of ''transmitter'' and ''responder''. In air navigation or radio frequency identification, a Transponder (aeronautics), flight transponder is an automated transceiver in an aircraft that emits a coded identifying signal in response to an interrogating received signal. In a communications satellite, a Transponder (satellite communications), satellite transponder receives signals over a range of uplink frequencies, usually from a satellite ground station; the transponder amplifies them, and re-transmits them on a different set of downlink frequencies to receivers on Earth, often without changing the content of the received signal or signals. Satellite/broadcast communications A communications satellite’s Communication channel, channels are called transponders because each is a separate transceiver or repeater. With digital video d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ku Band
The Ku band () is the portion of the electromagnetic spectrum in the microwave range of frequencies from 12 to 18 gigahertz (GHz). The symbol is short for "K-under" (originally german: Kurz-unten), because it is the lower part of the original NATO K band, which was split into three bands (Ku, K, and Ka) because of the presence of the atmospheric water vapor resonance peak at 22.24 GHz, (1.35 cm) which made the center unusable for long range transmission. In radar applications, it ranges from 12 to 18 GHz according to the formal definition of radar frequency band nomenclature in IEEE Standard 521–2002. Ku band is primarily used for satellite communications, most notably the downlink used by direct broadcast satellites to broadcast satellite television, and for specific applications such as NASA's Tracking Data Relay Satellite used for International Space Station (ISS) communications and SpaceX Starlink satellites. Ku band satellites are also used for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lithium-ion Battery
A lithium-ion or Li-ion battery is a type of rechargeable battery which uses the reversible reduction of lithium ions to store energy. It is the predominant battery type used in portable consumer electronics and electric vehicles. It also sees significant use for grid-scale energy storage and military and aerospace applications. Compared to other rechargeable battery technologies, Li-ion batteries have high energy densities, low self-discharge, and no memory effect (although a small memory effect reported in LFP cells has been traced to poorly made cells). Chemistry, performance, cost and safety characteristics vary across types of lithium-ion batteries. Most commercial Li-ion cells use intercalation compounds as the active materials. The anode or negative electrode is usually graphite, although silicon-carbon is also being increasingly used. Cells can be manufactured to prioritize either energy or power density. Handheld electronics mostly use lithium polymer batteries ... [...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] |
Gallium Arsenide
Gallium arsenide (GaAs) is a III-V direct band gap semiconductor with a Zincblende (crystal structure), zinc blende crystal structure. Gallium arsenide is used in the manufacture of devices such as microwave frequency integrated circuits, monolithic microwave integrated circuits, infrared light-emitting diodes, laser diodes, solar cells and optical windows. GaAs is often used as a substrate material for the epitaxial growth of other III-V semiconductors, including indium gallium arsenide, aluminum gallium arsenide and others. Preparation and chemistry In the compound, gallium has a +3 oxidation state. Gallium arsenide single crystals can be prepared by three industrial processes: * The vertical gradient freeze (VGF) process. * Crystal growth using a horizontal zone furnace in the Bridgman-Stockbarger technique, in which gallium and arsenic vapors react, and free molecules deposit on a seed crystal at the cooler end of the furnace. * Liquid encapsulated Czochralski process, Czoch ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Watt
The watt (symbol: W) is the unit of power or radiant flux in the International System of Units (SI), equal to 1 joule per second or 1 kg⋅m2⋅s−3. It is used to quantify the rate of energy transfer. The watt is named after James Watt (1736–1819), an 18th-century Scottish inventor, mechanical engineer, and chemist who improved the Newcomen engine with his own steam engine in 1776. Watt's invention was fundamental for the Industrial Revolution. Overview When an object's velocity is held constant at one metre per second against a constant opposing force of one newton, the rate at which work is done is one watt. : \mathrm In terms of electromagnetism, one watt is the rate at which electrical work is performed when a current of one ampere (A) flows across an electrical potential difference of one volt (V), meaning the watt is equivalent to the volt-ampere (the latter unit, however, is used for a different quantity from the real power of an electrical circuit). : ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monopropellant
Monopropellants are propellants consisting of chemicals that release energy through exothermic chemical decomposition. The molecular bond energy of the monopropellant is released usually through use of a catalyst. This can be contrasted with bipropellants that release energy through the chemical reaction between an oxidizer and a fuel. While stable under defined storage conditions, monopropellants decompose very rapidly under certain other conditions to produce a large volume of its own energetic (hot) gases for the performance of mechanical work. Although solid deflagrants such as nitrocellulose, the most commonly used propellant in firearms, could be thought of as monopropellants, the term is usually reserved for liquids in engineering literature. Uses The most common use of monopropellants is in low-impulse monopropellant rocket motors, such as reaction control thrusters, the usual propellant being hydrazine, p. 230 which is generally decomposed by exposure to an iridium, ... [...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] |
