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Defense Satellite Communications System
The Defense Satellite Communications System (DSCS) is a United States Space Force satellite constellation that provides the United States with military communications to support globally distributed military users. Beginning in 2007, DSCS began being replaced by the Wideband Global SATCOM system. A total of 14 DSCS-III satellites were launched between the early 1980s and 2003. Two satellites were launched aboard the Space Shuttle ''Atlantis'' in 1985 during the STS-51-J flight. As of 14 September 2021, six DSCS-III satellites were still operational. DSCS operations are currently run by the 4th Space Operations Squadron out of Schriever Space Force Base. Background DSCS went through three major phases — IDCSP (Interim Defense Communication Satellite Program), DSCS-II, and DSCS-III. Since the first launch, DSCS has been the "workhorse" of military satellite communications. All DSCS III satellites have exceeded their 10-year design life. The National Science Foundation use ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spin-stabilized Satellite
Spacecraft attitude control is the process of controlling the orientation of a spacecraft (vehicle or satellite) with respect to an inertial frame of reference or another entity such as the celestial sphere, certain fields, and nearby objects, etc. Controlling vehicle attitude requires actuators to apply the torques needed to orient the vehicle to a desired attitude, and algorithms to command the actuators based on the current attitude and specification of a desired attitude. Before and during attitude control can be performed, spacecraft attitude determination must be performed, which requires sensors for absolute or relative measurement. The broader integrated field that studies the combination of sensors, actuators and algorithms is called '' guidance, navigation and control'', which also involves non-attitude concepts, such as position determination and navigation. Motivation A spacecraft's attitude must typically be stabilized and controlled for a variety of reasons. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
General Electric
General Electric Company (GE) was an American Multinational corporation, multinational Conglomerate (company), conglomerate founded in 1892, incorporated in the New York (state), state of New York and headquartered in Boston. Over the years, the company had multiple divisions, including GE Aerospace, aerospace, GE Power, energy, GE HealthCare, healthcare, lighting, locomotives, appliances, and GE Capital, finance. In 2020, GE ranked among the Fortune 500, ''Fortune'' 500 as the 33rd largest firm in the United States by gross revenue. In 2023, the company was ranked 64th in the Forbes Global 2000, ''Forbes'' Global 2000. In 2011, GE ranked among the Fortune 20 as the 14th most profitable company, but later very severely underperformed the market (by about 75%) as its profitability collapsed. Two employees of GE—Irving Langmuir (1932) and Ivar Giaever (1973)—have been awarded the Nobel Prize. From 1986 until 2013, GE was the owner of the NBC television network through its ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Research And Development
Research and development (R&D or R+D), known in some countries as OKB, experiment and design, is the set of innovative activities undertaken by corporations or governments in developing new services or products. R&D constitutes the first stage of development of a potential new service or the production process. Although R&D activities may differ across businesses, the primary goal of an R&D department is to new product development, develop new products and services. R&D differs from the vast majority of corporate activities in that it is not intended to yield immediate profit, and generally carries greater risk and an uncertain return on investment. R&D is crucial for acquiring larger shares of the market through new products. ''R&D&I'' represents R&D with innovation. Background New product design and development is often a crucial factor in the survival of a company. In a global industrial landscape that is changing fast, firms must continually revise their design and range of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antenna (radio)
In radio-frequency engineering, an antenna (American English) or aerial (British English) is an electronic device that converts an alternating current, alternating electric current into radio waves (transmitting), or radio waves into an electric current (receiving). It is the interface between radio waves Radio propagation, propagating through space and electric currents moving in metal Electrical conductor, conductors, used with a transmitter or receiver (radio), receiver. In transmission (telecommunications), transmission, a radio transmitter supplies an electric current to the antenna's Terminal (electronics), terminals, and the antenna radiates the energy from the current as electromagnetic radiation, electromagnetic waves (radio waves). In receiver (radio), reception, an antenna intercepts some of the power of a radio wave in order to produce an electric current at its terminals, that is applied to a receiver to be amplifier, amplified. Antennas are essential components ... [...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 of ''transmitter'' and ''responder''. In air navigation or radio frequency identification, a 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 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 channels are called transponders because each is a separate transceiver or repeater. With digital video data compression and multiplexing, several video and audio channels may travel through a single tr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
X Band
The X band is the designation for a band of frequencies in the microwave radio region of the electromagnetic spectrum. In some cases, such as in communication engineering, the frequency range of the X band is set at approximately 7.0–11.2 GHz. In radar engineering, the frequency range is specified by the Institute of Electrical and Electronics Engineers (IEEE) as 8.0–12.0 GHz. The X band is used for radar, satellite communication, and wireless computer networks. Radar X band is used in radar applications, including continuous-wave, pulsed, single- polarization, dual-polarization, synthetic aperture radar, and phased arrays. X-band radar frequency sub-bands are used in civil, military, and government institutions for weather monitoring, air traffic control, maritime vessel traffic control, defense tracking, and vehicle speed detection for law enforcement. X band is often used in modern radars. The shorter wavelengths of the X band provide higher-r ... [...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 hazardous unless handled in solution as, for example, hydrazine hydrate (). Hydrazine is mainly used as a foaming agent in preparing Polymeric foam, polymer foams, but applications also include its uses as a precursor (chemistry), precursor to pharmaceuticals and agrochemicals, as well as a long-term storable propellant for in-outer space, space spacecraft propulsion. Additionally, hydrazine is used in various rocket propellant, rocket fuels and to prepare the gas precursors used in airbags. 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. , approximately 120,000 tons of hydrazine hydrate (corresponding to a 64% solution of hydrazine in water by weight) we ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nickel–cadmium Battery
The nickel–cadmium battery (Ni–Cd battery or NiCad battery) is a type of rechargeable battery using nickel oxide hydroxide and metallic cadmium as electrodes. The abbreviation ''Ni–Cd'' is derived from the chemical symbols of nickel (Ni) and cadmium (Cd): the abbreviation ''NiCad'' is a registered trademark of Saft Groupe S.A., SAFT Corporation, although this brand name is genericized trademark, commonly used to describe all Ni–Cd batteries. Battery (electricity)#Wet cell, Wet-cell nickel–cadmium batteries were invented in 1899. A Ni–Cd battery has a terminal voltage during discharge of around 1.2 volts which decreases little until nearly the end of discharge. The maximum electromotive force offered by a Ni–Cd cell is 1.3V. Ni–Cd batteries are made in a wide range of sizes and capacities, from portable sealed types interchangeable with carbon–zinc dry cells, to large ventilated cells used for standby power and motive power. Compared with other types of rechargeab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Watt
The watt (symbol: W) is the unit of Power (physics), 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 quantification (science), quantify the rate of Work (physics), energy transfer. The watt is named in honor of James Watt (1736–1819), an 18th-century Scottish people, Scottish inventor, mechanical engineer, and chemist who improved the Newcomen engine with his own Watt steam engine, steam engine in 1776, which became fundamental for the Industrial Revolution. Overview When an object's velocity is held constant at one meter per second against a constant opposing force of one Newton (unit), newton, the rate at which Work (physics), 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 vo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solar Cell
A solar cell, also known as a photovoltaic cell (PV cell), is an electronic device that converts the energy of light directly into electricity by means of the photovoltaic effect.Solar Cells chemistryexplained.com It is a type of photoelectric cell, a device whose electrical characteristics (such as Electric current, current, voltage, or Electrical resistance and conductance, resistance) vary when it is exposed to light. Individual solar cell devices are often the electrical building blocks of solar panel, photovoltaic modules, known colloquially as "solar panels". Almost all commercial PV cells consist of crystalline silicon, with a market share of 95%. Cadmium telluride thin-film solar cells account for the remainder. The common single-junction silicon solar cell can produce a maximum open-circuit voltage o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Defense Information Systems Agency
The Defense Information Systems Agency (DISA), known as the Defense Communications Agency (DCA) until 1991, is a United States Department of Defense (DoD) combat support agency. It is composed of military, federal civilians, and contractors. DISA provides information technology (IT) and communications support to the President, Vice President, Secretary of Defense, the Department of Defense, the combatant commands, and any individual or system contributing to the defense of the United States. History 1960s: The Defense Communications Agency DCA was established May 12, 1960, with the primary mission of operational control and management of the Defense Communications System (DCS). The initial headquarters for 34 DCA members was Wake Hall, one of a complex of three buildings (which included Midway Hall and Guam Hall) on the site where the parking lot of the Robert F. Kennedy Stadium in Washington, D.C., stands today. Navy Rear Admiral William D. Irvin became the first DCA ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
