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Starlette And Stella
Starlette (''Satellite de taille adaptée avec réflecteurs laser pour les études de la terre'', or ) and Stella are nearly identical French geodetic and geophysical satellites. Starlette was launched on 6 February 1975 and Stella on 26 September 1993. Starlette was the first passive laser satellite developed. Background Starlette's development dates back to at least 1972, when scientists at the Centre national d'études spatiales (CNES) were trying to determine a payload for the upcoming first flight of the new Diamant BP4 rocket. After consulting with the Smithsonian Astrophysical Observatory, CNES scientists decided to create a small geodetic satellite optimized for tracking by laser ranging. The project was approved within a few months after a feasibility study by the French atomic agency French Alternative Energies and Atomic Energy Commission, CEA determined the dense uranium core could be made nearly non-radioactive by using depleted uranium. The Groupe de recherches ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CNES
CNES () is the French national space agency. Headquartered in central Paris, the agency is overseen by the ministries of the Armed Forces, Economy and Finance and Higher Education, Research and Innovation. It operates from the Toulouse Space Centre and the Guiana Space Centre. The president of CNES is Philippe Baptiste. CNES is a member of Institute of Space, its Applications and Technologies. It is Europe's largest national organization of its type. History CNES was established under President Charles de Gaulle in 1961. It is the world's third oldest space agency, after the Soviet space program (Russia), and NASA (United States). CNES was responsible for the training of French astronauts, until the last active CNES astronauts transferred to the European Space Agency in 2001. , CNES is working with Germany and a few other governments to start a modest research effort with the hope to propose a LOX/methane reusable launch vehicle by mid-2015. If built, flight testing w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Uranium
Uranium is a chemical element; it has chemical symbol, symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Uranium radioactive decay, radioactively decays, usually by emitting an alpha particle. The half-life of this decay varies between 159,200 and 4.5 billion years for different isotopes of uranium, isotopes, making them useful for dating the age of the Earth. The most common isotopes in natural uranium are uranium-238 (which has 146 neutrons and accounts for over 99% of uranium on Earth) and uranium-235 (which has 143 neutrons). Uranium has the highest atomic weight of the primordial nuclide, primordially occurring elements. Its density is about 70% higher than that of lead and slightly lower than that of gold or tungsten. It occurs naturally in low concentrations of a few Parts-per notation#Parts-per expressions, parts per million in soil, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SPOT-3
SPOT (, lit. "Satellite for observation of Earth") is a commercial high-resolution optical Earth observation satellite system operating from space. It is run by Spot Image, based in Toulouse, France. It was initiated by the CNES (''Centre national d'études spatiales'' – the French space agency) in the 1970s and was developed in association with the SSTC (Belgian scientific, technical and cultural services) and the Swedish National Space Board (SNSB). It has been designed to improve the knowledge and management of the Earth by exploring the Earth's resources, detecting and forecasting phenomena involving climatology and oceanography, and monitoring human activities and natural phenomena. The SPOT system includes a series of satellites and ground control resources for satellite control and programming, image production, and distribution. Earlier satellites were launched using the European Space Agency's Ariane 2, 3, and 4 rockets, while SPOT 6 and SPOT 7 were launche ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ELA-2
The Guiana Space Centre (; CSG), also called Europe's Spaceport, is a spaceport to the northwest of Kourou in French Guiana, an overseas region of France in South America. Kourou is located approximately north of the equator at a latitude of 5°. In operation since 1968, it is a suitable location for a spaceport because of its near equatorial location and open sea to the east and north. At CSG, space launches are conducted by several European private companies and government agencies working together. The CSG land itself is managed by CNES, the French national space agency. The launch infrastructure built on the CSG land is owned by the European Space Agency. The private company Arianespace operates the launches including planning missions, handling customer relationships and overseeing the team at CSG that integrates and prepares vehicles for launch. The rockets themselves are designed and produced by other companies, ArianeGroup for the Ariane 6 and Avio for the Vega. Hi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Launch Vehicle
A launch vehicle is typically a rocket-powered vehicle designed to carry a payload (a crewed spacecraft or satellites) from Earth's surface or lower atmosphere to outer space. The most common form is the ballistic missile-shaped multistage rocket, but the term is more general and also encompasses vehicles like the Space Shuttle. Most launch vehicles operate from a launch pad, supported by a missile launch control center, launch control center and systems such as vehicle assembly and fueling. Launch vehicles are engineered with advanced aerodynamics and technologies, which contribute to high operating costs. An orbital spaceflight, orbital launch vehicle must lift its payload at least to the boundary of space, approximately and accelerate it to a horizontal velocity of at least . Suborbital spaceflight, Suborbital vehicles launch their payloads to lower velocity or are launched at elevation angles greater than horizontal. Practical orbital launch vehicles use chemical prope ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
French Guiana
French Guiana, or Guyane in French, is an Overseas departments and regions of France, overseas department and region of France located on the northern coast of South America in the Guianas and the West Indies. Bordered by Suriname to the west and Brazil to the east and south, French Guiana covers a total area of and a land area of . As of January 2025, it is home to 292,354 people. French Guiana is the second-largest Regions of France, region in France, being approximately one-seventh the size of metropolitan France, European France, and the largest Special member state territories and the European Union, outermost region within the European Union. It has a very low population density, with only . About half of its residents live in its capital, Cayenne. Approximately 98.9% of French Guiana is covered by forests, much of it Old-growth forest, primeval Tropical rainforest, rainforest. Guiana Amazonian Park, the largest national park in the European Union covers 41% of French ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Korou
Koru (former ''Kuri'') is a town (''belde'') in the Çınarcık District, Yalova Province, Turkey. Its population is 7,841 (2022). Up to 20th century the population was composed of Greeks. It is between Çınarcık to west and Yalova to east, all coastal places on the Anatolian side of Marmara Sea. Distance to Çınarcık is and to Yalova is . Name The name of the settlement was ''Kuri''. After the Population exchange between Greece and Turkey agreement, the former population of the settlement was replaced by the Turks from Serres and Drama Drama is the specific Mode (literature), mode of fiction Mimesis, represented in performance: a Play (theatre), play, opera, mime, ballet, etc., performed in a theatre, or on Radio drama, radio or television.Elam (1980, 98). Considered as a g ... in 1924. The former name was changed to a Turkish name with a similar sound and meaning small forest quite suitable for Koru. History In 1992, the settlement was declared a seat of town ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Launch Pad
A launch pad is an above-ground facility from which a rocket-powered missile or space vehicle is vertically launched. The term ''launch pad'' can be used to describe just the central launch platform (mobile launcher platform), or the entire complex (launch complex). The entire complex will include a ''launch mount'' or ''launch platform'' to physically support the vehicle, a service structure with umbilicals, and the infrastructure required to provide liquid-propellant rocket, propellants, cryogenic fluids, electrical power, communications, telemetry, rocket assembly, payload processing, storage facilities for propellants and gases, equipment, access roads, and drainage. Most launch pads include fixed service structures to provide one or more access platforms to assemble, inspect, and maintain the vehicle and to allow access to the spacecraft, including the loading of crew. The pad may contain a Flame deflector, flame deflection structure to prevent the intense heat of the roc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Retroreflector
A retroreflector (sometimes called a retroflector or cataphote) is a device or surface that reflects light or other radiation back to its source with minimum scattering. This works at a wide range of angle of incidence (optics), angle of incidence, unlike a planar mirror, which does this only if the mirror is exactly perpendicular to the wave front, having a zero angle of incidence. Being directed, the retroflector's reflection (physics), reflection is brighter than that of a diffuse reflector. Corner reflectors and Cat's eye (road), cat's eye reflectors are the most used kinds. Types There are several ways to obtain retroreflection: Corner reflector A set of three mutually perpendicular reflective surfaces, placed to form the internal corner of a cube, work as a retroreflector. The three corresponding normal vectors of the corner's sides form a basis in which to represent the direction of an arbitrary incoming ray, . When the ray reflects from the first side, say x, the ray' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atmosphere Of Earth
The atmosphere of Earth is composed of a layer of gas mixture that surrounds the Earth's planetary surface (both lands and oceans), known collectively as air, with variable quantities of suspended aerosols and particulates (which create weather features such as clouds and hazes), all retained by gravity of Earth, Earth's gravity. The atmosphere serves as a protective buffer between the Earth's surface and outer space, shields the surface from most meteoroids and ultraviolet solar irradiance, solar radiation, keeps it warm and reduces diurnal temperature variation (temperature extremes between daytime, day and night) through heat retention (greenhouse effect), redistributes heat and moisture among different regions via air currents, and provides the atmospheric chemistry, chemical and climate conditions allowing life to exist and evolution, evolve on Earth. By mole fraction (i.e., by quantity of molecules), dry air contains 78.08% nitrogen, 20.95% oxygen, 0.93% argon, 0.04% carbon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aerobraking
Aerobraking is a spaceflight maneuver that reduces the high point of an elliptical orbit (apoapsis) by flying the vehicle through the atmosphere at the low point of the orbit (periapsis). The resulting drag slows the spacecraft. Aerobraking is used when a spacecraft requires a low orbit after arriving at a body with an atmosphere, as it requires less fuel than using propulsion to slow down. Method When an interplanetary vehicle arrives at its destination, it must reduce its velocity to achieve orbit or to land. To reach a low, near-circular orbit around a body with substantial gravity (as is required for many scientific studies), the required velocity changes can be on the order of kilometers per second. Using propulsion, the rocket equation dictates that a large fraction of the spacecraft mass must consist of fuel. This reduces the science payload and/or requires a large and expensive rocket. Provided the target body has an atmosphere, aerobraking can be used to reduce fuel re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drag (physics)
In fluid dynamics, drag, sometimes referred to as fluid resistance, is a force acting opposite to the direction of motion of any object moving with respect to a surrounding fluid. This can exist between two fluid layers, two solid surfaces, or between a fluid and a solid surface. Drag forces tend to decrease fluid velocity relative to the solid object in the fluid's path. Unlike other resistive forces, drag force depends on velocity. Drag force is proportional to the relative velocity for low-speed flow and is proportional to the velocity squared for high-speed flow. This distinction between low and high-speed flow is measured by the Reynolds number. Drag is instantaneously related to vorticity dynamics through the Josephson-Anderson relation. Examples Examples of drag include: * Net force, Net Aerodynamic force, aerodynamic or Fluid dynamics, hydrodynamic force: Drag acting opposite to the direction of movement of a solid object such as cars, aircraft, and boat hulls. * Viscou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
