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Gravity-gradient Stabilization
Gravity-gradient stabilization or tidal stabilization is a passive method of stabilizing artificial satellites or space tethers in a fixed orientation using only the mass distribution of the orbited body and the gravitational field. The main advantage over using active stabilization with propellants, gyroscopes or reaction wheels is the low use of power and resources. It can also reduce or prevent the risk of propellant contamination of sensitive components. The technique exploits the Earth's gravitational field and tidal forces to keep the spacecraft aligned along the desired orientation. The gravity of the Earth decreases according to the inverse-square law, and by extending the long axis perpendicular to the orbit, the "lower" part of the orbiting structure will be more attracted to the Earth. The effect is that the satellite will tend to align its axis of minimum moment of inertia vertically. Early satellite usage GGSE-1, launched in 1964, was a low Earth orbit satellite ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spacecraft Attitude Control
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. It ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Earth's Magnetic Field
Earth's magnetic field, also known as the geomagnetic field, is the magnetic field that extends from structure of Earth, Earth's interior out into space, where it interacts with the solar wind, a stream of charged particles emanating from the Sun. The magnetic field is generated by electric currents due to the motion of convection currents of a mixture of molten iron and nickel in Earth's outer core: these convection currents are caused by heat escaping from the core, a natural process called a geodynamo. The magnitude of Earth's magnetic field at its surface ranges from . As an approximation, it is represented by a field of a magnetic dipole currently tilted at an angle of about 11° with respect to Earth's rotational axis, as if there were an enormous bar magnet placed at that angle through the center of Earth. The North geomagnetic pole (Ellesmere Island, Nunavut, Canada) actually represents the South pole of Earth's magnetic field, and conversely the South geomagnetic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Explorer 49
Explorer 49 (also called Radio Astronomy Explorer-2, RAE-B) was a NASA satellite launched on 10 June 1973, for long wave radio astronomy research. It had four X-shaped antenna elements, which made it one of the largest spacecraft ever built. Mission The Radio Astronomy Explorer B (RAE-B) mission was the second of a pair of RAE satellites. It was placed into lunar orbit to provide radio astronomical measurements of the planets, the Sun, and the galaxy over the frequency range of 25-kHz to 13.1-MHz. The experiment complement consisted of two Ryle-Vonberg radiometers (nine channels each), three swept-frequency burst receivers (32 channels each), and an impedance probe for calibration. The experiment antenna package, made of BeCu, consisted of very long traveling wave antennas forming an X configuration: a upper V-antenna pointed away from the Moon; a lower V-antenna pointed toward the Moon; and a dipole antenna parallel to the lunar surface. There was also a boron libration ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DODGE
Dodge is an American brand of automobiles and a division of Stellantis, based in Auburn Hills, Michigan. Dodge vehicles have historically included performance cars, and for much of its existence, Dodge was Chrysler's mid-priced brand above Plymouth. Founded as the Dodge Brothers Company machine shop by brothers Horace Elgin Dodge and John Francis Dodge in the early 1900s, Dodge was originally a supplier of parts and assemblies to Detroit-based automakers like Ford. They began building complete automobiles under the "Dodge Brothers" brand in 1914, predating the founding of the Chrysler Corporation. The factory located in Hamtramck, Michigan, was the Dodge main factory from 1910 until it closed in January 1980. John Dodge died from the Spanish flu in January 1920, having lungs weakened by tuberculosis 20 years earlier. Horace died in December of the same year, perhaps weakened by the Spanish flu, but the cause of death was cirrhosis of the liver. Their company was sold b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ATS-4
ATS-4 (Applications Technology Satellite) also known as ATS-D was a communications satellite launched by NASA on August 10, 1968 from Cape Canaveral through an Atlas-Centaur (AC-17) rocket. Objectives The objective of ATS-4 was to investigate the possibilities of a gravity gradient stabilization system (the method of stabilizing artificial satellites). Features The satellite has a cylindrical shape with a diameter and height (about considering the motor cover) with the surface covered by solar panels that generated a maximum of 350 W of power, and stabilized by gravity gradient. It was based on the Hughes Aircraft HS-306 bus. Instruments A total of four experiments were conducted during the mission: * Microwave Transponder * Gravity Gradient Stabilization * Image Orthicon (Day/Night) Camera * Ion Thruster Mission The Atlas and Centaur stages performed satisfactorily and placed the Centaur/ATS-4 in an elliptical parking orbit. However the Centaur stage failed to re-ignit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ATS-2
ATS-2 (Applications Technology Satellite) was a communications satellite launched by NASA on April 6, 1967, on an Atlas-Agena D rocket from Cape Canaveral Air Force Station, Cape Canaveral. Objectives The ATS-2 had the following objectives: test new concepts in spacecraft design, propulsion and stabilization; capture high quality images of cloud cover; collect data measurements in an aerospace environment; and test improved communication systems. Features The satellite had a cylindrical shape with a diameter and a height of . After including the motor cover, the satellite was about tall. The surface of the satellite was covered by solar panels, and it utilized gravity-gradient stabilization for control. Experiments The following 12 experiments were conducted: * Radio astronomy * Magnetospheric electric convection field, Magnetospheric electric fields * Electron magnetic spectrometer deflection * Particle telescope * Omnidirectional proton and electron detectors * V ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Applications Technology Satellite
The Applications Technology Satellites (ATS) were a series of experimental satellites launched by NASA, under the supervision of, among others, Wernher von Braun. The program was launched in 1966 to test the feasibility of placing a satellite into geosynchronous orbit. The satellites were primarily designed to act as communication satellites, but also carried equipment related to meteorology and navigation. ATS-6 was the world's first educational satellite as well as world's first experimental Direct Broadcast Satellite (DBS) as part of the Satellite Instructional Television Experiment (SITE) between NASA and ISRO The Indian Space Research Organisation (ISRO ) is India's national space agency, headquartered in Bengaluru, Karnataka. It serves as the principal research and development arm of the Department of Space (DoS), overseen by the Prime Minister o .... Summary of Missions See also * Geostationary Operational Environmental Satellite * Synchronous Meteorologica ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geosynchronous Orbit
A geosynchronous orbit (sometimes abbreviated GSO) is an Earth-centered orbit with an orbital period that matches Earth's rotation on its axis, 23 hours, 56 minutes, and 4 seconds (one sidereal day). The synchronization of rotation and orbital period means that, for an observer on Earth's surface, an object in geosynchronous orbit returns to exactly the same position in the sky after a period of one sidereal day. Over the course of a day, the object's position in the sky may remain still or trace out a path, typically in a figure-8 form, whose precise characteristics depend on the orbit's inclination and eccentricity. A circular geosynchronous orbit has a constant altitude of . A special case of geosynchronous orbit is the geostationary orbit (often abbreviated ''GEO''), which is a circular geosynchronous orbit in Earth's equatorial plane with both inclination and eccentricity equal to 0. A satellite in a geostationary orbit remains in the same position in the sky to observers ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
OV1-10
Orbiting Vehicle 1-10 (also known as OV1-10), launched 11 December 1966 along with OV1-9, was the tenth (seventh successful) satellite in the OV1 series of the United States Air Force's Orbiting Vehicle program. Designed to observe atmospheric airglow, X-ray and cosmic radiation, OV1-10 returned significant data on the Sun as well as on geophysical phenomena in Earth's magnetic field. OV1-10 reentered Earth's atmosphere on 30 November 2002. History The Orbiting Vehicle satellite program arose from a US Air Force initiative, begun in the early 1960s, to reduce the expense of space research. Through this initiative, satellites would be standardized to improve reliability and cost-efficiency, and where possible, they would fly on test vehicles or be piggybacked with other satellites. In 1961, the Air Force Office of Aerospace Research (OAR) created the Aerospace Research Support Program (ARSP) to request satellite research proposals and choose mission experiments. The USAF Space a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
OV1-17
Orbiting Vehicle 1–17 (also known as OV1-17) was solar radiation satellite, part of a quadruple payload launch on 18 March 1969. Part of the Orbiting Vehicle#OV1, OV1 series of USAF satellites, using standardized designs and sent to orbit on decommissioned SM-65 Atlas, Atlas ICBMs to reduce development and launching costs, OV1-17 was launched via SM-65F_Atlas, Atlas F along with OV1-18, OV1-19, and OV1-17A. It's primary purpose was to measure the effects of the Earth's ionosphere on detection, control, communications, and tracking systems in space. Because its stabilization system failed to deploy, and because of the abbreviated data sets, the flight yielded relatively few scientific results. Still, 11 papers were published using OV1-17 data. History The Orbiting Vehicle satellite program arose from a US Air Force initiative, begun in the early 1960s, to reduce the expense of space research. Through this initiative, satellites would be standardized to improve reliability and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
OV1-86
Orbiting Vehicle 1-86 (also known as OV1-86 ) was a satellite launched 27 July 1967 to measure the temperature radiation properties of different types of terrain. Part of the OV1 series of USAF satellites, using standardized designs and sent to orbit on decommissioned Atlas ICBMs to reduce development and launching costs, OV1-86 was launched with two other satellites in the series, OV1-11 and OV1-12, in the first triple launch of the program. It was the only OV1 satellite to be cobbled together from two of its sister satellites, utilizing the unused body on OV1-8 and the unused propulsion module on OV1-6. OV1-86's was only partially successful due to the failure of its Vertistat gravity-gradient stabilization system. The satellite reentered the Earth's atmosphere on 22 February 1972. History The Orbiting Vehicle satellite program arose from a US Air Force initiative, begun in the early 1960s, to reduce the expense of space research. Through this initiative, satellites would ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
