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Marisat
Marisat satellites were the first maritime telecommunications satellites and were designed to provide dependable telecommunications for commercial shipping and the U.S. Navy from stable geosynchronous orbital locations over the three major ocean regions. The three Marisat satellites, F1, F2, and F3, were built by Hughes Aircraft Corporation (HAC) for COMSAT Corporation starting in 1973. The satellites were designed to provide maritime telecommunications services in three large ocean areas, the Atlantic Ocean, the Pacific Ocean, and the Indian Ocean, and were located at 72.5° East longitude, 176.5° E, and 345° E in the geosynchronous orbital arc. The three-satellite Marisat system served as the initial INMARSAT constellation. Ownership of the three Marisat satellites was transferred to Lockheed Martin when it bought COMSAT Corp in 2000. The Marisat-F2 satellite was acquired by INTELSAT as part of the COMSAT General Corp. acquisition in October 2004. The three satellit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
COMSAT
COMSAT (Communications Satellite Corporation) is a global telecommunications company based in the United States. By 2007, it had branches in Brazil, Argentina, Colombia, Mexico, Peru, Venezuela and several other countries in the Americas. Although it operated many kinds of data communication technologies, it is best known for its satellite communication services. History COMSAT Corporation was created by the Communications Satellite Act of 1962 and incorporated as a publicly traded company in 1963. The primary goal of COMSAT was to serve as a public, federally funded corporation intended to develop a commercial and international satellite communication system press. Although the corporation was government regulated, it was equally owned by some major communications corporations and independent investors. COMSAT began operations with its headquarters in Washington, D.C., in 1962, with a six-person founding board of directors appointed by President John F. Kennedy, includ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
COMSAT Mobile Communications
COMSAT Mobile Communications (CMC), a telecommunications company which provides global mobile communications solutions to the maritime, land mobile and aeronautical communities, and offers data, voice, fax, telex and video capabilities via the Inmarsat geosynchronous satellite constellation through two earth station facilities in Southbury, Connecticut, and Santa Paula, California. CMC was a business unit of COMSAT Corporation of Bethesda, MD (NYSE: CQ) (delisted). In concert with COMSAT General Corporation's (another business unit of COMSAT Corp) MARISAT system, CMC sparked a revolution in medium- and long-distance maritime ship-to-shore communication, augmenting and eventually replacing cumbersome and technically challenging high-power radiotelegraph and radiotelephone equipment with solid state, user-friendly satellite terminals which required relatively minimal training to use in voice, fax, and telex modes that were impervious to normal radio propagation conditions and unaffe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Syncom
Syncom (for "synchronous communication satellite") 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 (now the Boeing Satellite Development Center). 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. In the 1980s, the series was continued as Syncom IV with some much larger satellites, also manufactured by Hughes. They were leased to the United States military under the Leasat program. Syncom 1, 2 and 3 Common features The three early Syncom satellites were experimental spacecraft built by Hughes Aircraft Company's facility in Culver City, California, by a team led by Harold Rosen, Don Williams, and Thomas Hudspeth. All three satellites were cylindrical in shape, with a diameter of about and a height of about . Pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
South Pole
The South Pole, also known as the Geographic South Pole, Terrestrial South Pole or 90th Parallel South, is one of the two points where Earth's axis of rotation intersects its surface. It is the southernmost point on Earth and lies antipodally on the opposite side of Earth from the North Pole, at a distance of 12,430 miles (20,004 km) in all directions. Situated on the continent of Antarctica, it is the site of the United States Amundsen–Scott South Pole Station, which was established in 1956 and has been permanently staffed since that year. The Geographic South Pole is distinct from the South Magnetic Pole, the position of which is defined based on Earth's magnetic field. The South Pole is at the centre of the Southern Hemisphere. Geography For most purposes, the Geographic South Pole is defined as the southern point of the two points where Earth's axis of rotation intersects its surface (the other being the Geographic North Pole). However, Earth's axis of rotat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antarctic
The Antarctic ( or , American English also or ; commonly ) is a polar region around Earth's South Pole, opposite the Arctic region around the North Pole. The Antarctic comprises the continent of Antarctica, the Kerguelen Plateau and other island territories located on the Antarctic Plate or south of the Antarctic Convergence. The Antarctic region includes the ice shelves, waters, and all the island territories in the Southern Ocean situated south of the Antarctic Convergence, a zone approximately wide varying in latitude seasonally. The region covers some 20 percent of the Southern Hemisphere, of which 5.5 percent (14 million km2) is the surface area of the Antarctica continent itself. All of the land and ice shelves south of 60°S latitude are administered under the Antarctic Treaty System. Biogeographically, the Antarctic realm is one of eight biogeographic realms of Earth's land surface. Geography As defined by the Antarctic Treaty System, the Antarctic r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
National Science Foundation
The National Science Foundation (NSF) is an independent agency of the United States government that supports fundamental research and education in all the non-medical fields of science and engineering. Its medical counterpart is the National Institutes of Health. With an annual budget of about $8.3 billion (fiscal year 2020), the NSF funds approximately 25% of all federally supported basic research conducted by the United States' colleges and universities. In some fields, such as mathematics, computer science, economics, and the social sciences, the NSF is the major source of federal backing. The NSF's director and deputy director are appointed by the President of the United States and confirmed by the United States Senate, whereas the 24 president-appointed members of the National Science Board (NSB) do not require Senate confirmation. The director and deputy director are responsible for administration, planning, budgeting and day-to-day operations of the foundation, while t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
TacSat-1
TacSat-1 was an experimental satellite built by the Naval Research Laboratory (NRL) on behalf of the United States Department of Defense (DoD) Office of Force Transformation (OFT). It was the planned payload of the sixth launch of the SpaceX Falcon 1. It was however never launched into space. The second satellite in the series, TacSat-2, launched before TacSat-1 and this led to the cancellation of TacSat-1's launch. TacSat-1 would have carried a variety of experimental payloads. Much of the payload software was implemented through the use of bash scripts operating on the "Copperfield-2" general-purpose computer system aboard the spacecraft. Purpose The TacSat series of experimental spacecraft are designed to allow military commanders on a battlefield to request and obtain imagery and other data from a satellite as it passes overhead. Collected data will be delivered to field commanders in minutes rather than hours or days. The sensor on TacSat-1 could collect color images shar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nadir
The nadir (, ; ar, نظير, naẓīr, counterpart) is the direction pointing directly ''below'' a particular location; that is, it is one of two vertical directions at a specified location, orthogonal to a horizontal flat surface. The direction opposite of the nadir is the zenith. Definitions Space science Since the concept of ''being below'' is itself somewhat vague, scientists define the nadir in more rigorous terms. Specifically, in astronomy, geophysics and related sciences (e.g., meteorology), the nadir at a given point is the local vertical direction pointing in the direction of the force of gravity at that location. The term can also be used to represent the lowest point that a celestial object reaches along its apparent daily path around a given point of observation (i.e. the object's ''lower culmination''). This can be used to describe the position of the Sun, but it is only technically accurate for one latitude at a time and only possible at the low latitudes. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antenna (radio)
In radio engineering, an antenna or aerial is the interface between radio waves propagating through space and electric currents moving in metal conductors, used with a transmitter or receiver. In transmission, a radio transmitter supplies an electric current to the antenna's terminals, and the antenna radiates the energy from the current as electromagnetic wave In physics, electromagnetic radiation (EMR) consists of waves of the electromagnetic (EM) field, which propagate through space and carry momentum and electromagnetic radiant energy. It includes radio waves, microwaves, infrared, (visib ...s (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 of all radio equipment. An antenna is an array of conductor (material), conductors (Driven element, elements), elect ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Earth
Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surface is made up of the ocean, dwarfing Earth's polar ice, lakes, and rivers. The remaining 29% of Earth's surface is land, consisting of continents and islands. Earth's surface layer is formed of several slowly moving tectonic plates, which interact to produce mountain ranges, volcanoes, and earthquakes. Earth's liquid outer core generates the magnetic field that shapes the magnetosphere of the Earth, deflecting destructive solar winds. The atmosphere of the Earth consists mostly of nitrogen and oxygen. Greenhouse gases in the atmosphere like carbon dioxide (CO2) trap a part of the energy from the Sun close to the surface. Water vapor is widely present in the atmosphere and forms clouds that cover most of the planet. More solar e ... [...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] |
Gyroscopic
A gyroscope (from Ancient Greek γῦρος ''gŷros'', "round" and σκοπέω ''skopéō'', "to look") is a device used for measuring or maintaining orientation and angular velocity. It is a spinning wheel or disc in which the axis of rotation (spin axis) is free to assume any orientation by itself. When rotating, the orientation of this axis is unaffected by tilting or rotation of the mounting, according to the conservation of angular momentum. Gyroscopes based on other operating principles also exist, such as the microchip-packaged MEMS gyroscopes found in electronic devices (sometimes called gyrometers), solid-state ring lasers, fibre optic gyroscopes, and the extremely sensitive quantum gyroscope. Applications of gyroscopes include inertial navigation systems, such as in the Hubble Space Telescope, or inside the steel hull of a submerged submarine. Due to their precision, gyroscopes are also used in gyrotheodolites to maintain direction in tunnel mining. Gyroscopes can ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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