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Spacecraft Propulsion
Spacecraft propulsion is any method used to accelerate spacecraft and artificial satellites. In-space propulsion exclusively deals with propulsion systems used in the vacuum of space and should not be confused with space launch or atmospheric entry. Several methods of pragmatic spacecraft propulsion have been developed, each having its own drawbacks and advantages. Most satellites have simple reliable chemical thrusters (often monopropellant rockets) or resistojet rockets for orbital station-keeping, while a few use Reaction wheel, momentum wheels for attitude control. Russian and antecedent Soviet bloc satellites have used Spacecraft electric propulsion, electric propulsion for decades, and newer Western geo-orbiting spacecraft are starting to use them for north–south station-keeping and orbit raising. Interplanetary vehicles mostly use chemical rockets as well, although a few have used electric propulsion such as ion thrusters and Hall-effect thrusters. Various technologies ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shuttle Main Engine Test Firing
The original meaning of the word shuttle is the device used in weaving to carry the weft. By reference to the continual to-and-fro motion associated with that, the term was then applied in transportation and then in other spheres. Thus the word may now also refer to: Transport Air transport * Air shuttle, a type of flight which quickly connects nearby destinations * Delta Shuttle, the brand name for Delta Air Lines' air shuttle service * Rossi Shuttle Quik, an Italian ultralight trike design * Shuttle America, a regional airline based in Indianapolis, Indiana * Shuttle by United, a regional airline operated as a subsidiary of United Airlines * Shuttle Carrier Aircraft, modified Boeing 747 airliners used to transport Space Shuttle orbiters * US Airways Shuttle, the brand name for an hourly service offered by US Airways * The call sign for domestic (UK internal) British Airways flights - international flights use Speedbird Land transport Automotive brands * Fit Shuttle, t ... [...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] |
Leaching (chemistry)
Leaching is the process of a solute becoming detached or extracted from its carrier substance by way of a solvent. Leaching is a naturally occurring process which scientists have adapted for a variety of applications with a variety of methods. Specific extraction methods depend on the soluble characteristics relative to the sorbent material such as concentration, distribution, nature, and size. Leaching can occur naturally seen from plant substances (inorganic and organic), solute leaching in soil, and in the decomposition of organic materials. Leaching can also be applied affectedly to enhance water quality and contaminant removal, as well as for disposal of hazardous waste products such as fly ash, or rare earth elements (REEs). Understanding leaching characteristics is important in preventing or encouraging the leaching process and preparing for it in the case where it is inevitable. In an ideal leaching equilibrium stage, all the solute is dissolved by the solvent, lea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Free Fall
In classical mechanics, free fall is any motion of a physical object, body where gravity is the only force acting upon it. A freely falling object may not necessarily be falling down in the vertical direction. If the common definition of the word "fall" is used, an object moving upwards is not considered to be falling, but using scientific definitions, if it is subject to only the force of gravity, it is said to be in free fall. The Moon is thus in free fall around the Earth, though its orbital speed keeps it in orbit of the Moon, very far orbit from the Earth's surface. In a roughly uniform gravitational field gravity acts on each part of a body approximately equally. When there are no other forces, such as the normal force exerted between a body (e.g. an astronaut in orbit) and its surrounding objects, it will result in the sensation of weightlessness, a condition that also occurs when the gravitational field is weak (such as when far away from any source of gravity). The ter ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Escape Velocity
In celestial mechanics, escape velocity or escape speed is the minimum speed needed for an object to escape from contact with or orbit of a primary body, assuming: * Ballistic trajectory – no other forces are acting on the object, such as propulsion and friction * No other gravity-producing objects exist. Although the term ''escape velocity'' is common, it is more accurately described as a speed than as a velocity because it is independent of direction. Because gravitational force between two objects depends on their combined mass, the escape speed also depends on mass. For artificial satellites and small natural objects, the mass of the object makes a negligible contribution to the combined mass, and so is often ignored. Escape speed varies with distance from the center of the primary body, as does the velocity of an object traveling under the gravitational influence of the primary. If an object is in a circular or elliptical orbit, its speed is always less than the es ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gravity Well
A sphere of influence (SOI) in astrodynamics and astronomy is the oblate spheroid-shaped region where a particular celestial body exerts the main gravitational influence on an orbiting object. This is usually used to describe the areas in the Solar System where planets dominate the orbits of surrounding objects such as moons, despite the presence of the much more massive but distant Sun. In the patched conic approximation, used in estimating the trajectories of bodies moving between the neighbourhoods of different bodies using a two-body approximation, ellipses and hyperbolae, the SOI is taken as the boundary where the trajectory switches which mass field it is influenced by. It is not to be confused with the sphere of activity which extends well beyond the sphere of influence. Models The most common base models to calculate the sphere of influence is the Hill sphere and the Laplace sphere, but updated and particularly more dynamic ones have been described. The general e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orbital Inclination Change
Orbital inclination change is an orbital maneuver aimed at changing the inclination of an orbiting body's orbit. This maneuver is also known as an orbital plane change as the plane of the orbit is tipped. This maneuver requires a change in the orbital velocity vector (delta-v) at the orbital nodes (i.e. the point where the initial and desired orbits intersect, the line of orbital nodes is defined by the intersection of the two orbital planes). In general, inclination changes can take a very large amount of delta-v to perform, and most mission planners try to avoid them whenever possible to conserve fuel. This is typically achieved by launching a spacecraft directly into the desired inclination, or as close to it as possible so as to minimize any inclination change required over the duration of the spacecraft life. Planetary flybys are the most efficient way to achieve large inclination changes, but they are only effective for interplanetary missions. Efficiency The simplest ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Impulse (physics)
In classical mechanics, impulse (symbolized by or Imp) is the change in momentum of an object. If the initial momentum of an object is , and a subsequent momentum is , the object has received an impulse : \mathbf=\mathbf_2 - \mathbf_1. Momentum is a Vector (physics), vector quantity, so impulse is also a vector quantity: \sum \mathbf \times \Delta t = \Delta \mathbf. Newton’s second law of motion states that the rate of change of momentum of an object is equal to the resultant force acting on the object: \mathbf=\frac, so the impulse delivered by a steady force acting for time is: \mathbf=\mathbf \Delta t. The impulse delivered by a varying force acting from time to is the integral of the force with respect to time: \mathbf= \int_a^b\mathbf \, \mathrmt. The International System of Units, SI unit of impulse is the newton second (N⋅s), and the dimensional analysis, dimensionally equivalent unit of momentum is the kilogram metre per second (kg⋅m/s). The correspond ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ascent
Ascent or The Ascent may refer to: Publications * ''Ascent'' (magazine), an independent, not-for-profit magazine * ''Ascent'' (journal), a literary journal based at Concordia College * ''Ascent'' (novel), by Jed Mercurio * '' Times Ascent'', a weekly supplement of ''The Times of India'' newspaper Film and TV * ''The Ascent'' (1977 film), a Soviet film set in World War II * The Ascent (1994 film), an American war adventure film * The Ascent (2019 film), also known as Black Ops or Stairs, is a 2019 action horror film * '' Kodiyettam'' (''Ascent''), 1977 Indian film written and directed by Adoor Gopalakrishnan * "The Ascent" (''Star Trek: Deep Space Nine''), a 1996 episode of the television series ''Star Trek: Deep Space Nine'' * "Ascent" (''American Crime Story''), an episode of the second season of ''American Crime Story'' * "Ascent" (''Dead Zone''), an episode of ''The Dead Zone'' * The Ascent ''(Ninjago)'', an episode of ''Ninjago'' Music * ''Ascents'' (album), 2000 a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Landings On Extraterrestrial Bodies
This is a list of all spacecraft landings on other planets and bodies in the Solar System, including soft landings and both intended and unintended hard impacts. The list includes orbiters that were intentionally crashed, but not orbiters which later crashed in an unplanned manner due to orbital decay. Colour key: : Planets Mercury Venus Mars Jupiter Jupiter is a gas giant with a very large atmospheric pressure and internal temperature and thus there is no known hard surface on which to "land". All missions listed here are impacts on Jupiter. Saturn Saturn is a gas giant with a very large atmospheric pressure and internal temperature and thus there is no known hard surface on which to "land". All missions listed here are impacts on Saturn. Planetary moons Earth's Moon Moons of Saturn ;Titan Other bodies Asteroids Comets See also * Deliberate crash landings on extraterrestrial bodies * List of artificial objects on extraterrestrial surfaces * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hohmann Transfer Orbit
In astronautics, the Hohmann transfer orbit () is an orbital maneuver used to transfer a spacecraft between two orbits of different altitudes around a central body. For example, a Hohmann transfer could be used to raise a satellite's orbit from low Earth orbit to geostationary orbit. In the idealized case, the initial and target orbits are both circular orbit, circular and orbital plane, coplanar. The maneuver is accomplished by placing the craft into an elliptical orbit, elliptical transfer orbit that is tangential to both the initial and target orbits. The maneuver uses two impulse (physics), impulsive engine burns: the first establishes the transfer orbit, and the second adjusts the orbit to match the target. The Hohmann maneuver often uses the lowest possible amount of impulse (which consumes a proportional amount of delta-v, and hence propellant) to accomplish the transfer, but requires a relatively longer travel time than higher-impulse transfers. In some cases where one ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geostationary Orbit
A geostationary orbit, also referred to as a geosynchronous equatorial orbit''Geostationary orbit'' and ''Geosynchronous (equatorial) orbit'' are used somewhat interchangeably in sources. (GEO), is a circular orbit, circular geosynchronous orbit in altitude above Earth's equator, in radius from Earth's center, and following the retrograde and prograde motion, direction of Earth's rotation. An object in such an orbit has an orbital period equal to Earth's rotational period, one sidereal time, sidereal day, and so to ground observers it appears motionless, in a fixed position in the sky. The concept of a geostationary orbit was popularised by the science fiction writer Arthur C. Clarke in the 1940s as a way to revolutionise telecommunications, and the first satellite to be placed in this kind of orbit was launched in 1963. Communications satellites are often placed in a geostationary orbit so that Earth-based satellite dish, satellite antennas do not have to rotate to track t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
