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Orbital Maneuver
In spaceflight, an orbital maneuver (otherwise known as a burn) is the use of propulsion systems to change the orbit of a spacecraft. For spacecraft far from Earth (for example those in orbits around the Sun) an orbital maneuver is called a ''deep-space maneuver (DSM)''. The rest of the flight, especially in a transfer orbit, is called ''coasting''. General Rocket equation The Tsiolkovsky rocket equation, or ideal rocket equation is an equation that is useful for considering vehicles that follow the basic principle of a rocket: where a device that can apply acceleration to itself (a thrust) by expelling part of its mass with high speed and moving due to the conservation of momentum. Specifically, it is a mathematical equation that relates the delta-v (the maximum change of speed of the rocket if no other external forces act) with the effective exhaust velocity and the initial and final mass of a rocket (or other reaction engine.) For any such maneuver (or journey involvin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spaceflight
Spaceflight (or space flight) is an application of astronautics to fly spacecraft into or through outer space, either with or without humans on board. Most spaceflight is uncrewed and conducted mainly with spacecraft such as satellites in orbit around Earth, but also includes space probes for flights beyond Earth orbit. Such spaceflight operates either by telerobotic or autonomous control. The more complex human spaceflight has been pursued soon after the first orbital satellites and has reached the Moon and permanent human presence in space around Earth, particularly with the use of space stations. Human spaceflight programs include the Soyuz, Shenzhou, the past Apollo Moon landing and the Space Shuttle programs, with currently the International Space Station as the main destination of human spaceflight missions while China's Tiangong Space Station is under construction. Spaceflight is used for placing in Earth's orbit communications satellites, reconnaissance satellites ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Velocity
Velocity is the directional speed of an object in motion as an indication of its rate of change in position as observed from a particular frame of reference and as measured by a particular standard of time (e.g. northbound). Velocity is a fundamental concept in kinematics, the branch of classical mechanics that describes the motion of bodies. Velocity is a physical vector quantity; both magnitude and direction are needed to define it. The scalar absolute value (magnitude) of velocity is called , being a coherent derived unit whose quantity is measured in the SI (metric system) as metres per second (m/s or m⋅s−1). For example, "5 metres per second" is a scalar, whereas "5 metres per second east" is a vector. If there is a change in speed, direction or both, then the object is said to be undergoing an ''acceleration''. Constant velocity vs acceleration To have a ''constant velocity'', an object must have a constant speed in a constant direction. Constant direction cons ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Physicist
A physicist is a scientist who specializes in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe. Physicists generally are interested in the root or ultimate causes of phenomena, and usually frame their understanding in mathematical terms. Physicists work across a wide range of research fields, spanning all length scales: from sub-atomic and particle physics, through biological physics, to cosmological length scales encompassing the universe as a whole. The field generally includes two types of physicists: experimental physicists who specialize in the observation of natural phenomena and the development and analysis of experiments, and theoretical physicists who specialize in mathematical modeling of physical systems to rationalize, explain and predict natural phenomena. Physicists can apply their knowledge towards solving practical problems or to developing new technologies (also known as applie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Germany
Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated between the Baltic and North seas to the north, and the Alps to the south; it covers an area of , with a population of almost 84 million within its 16 constituent states. Germany borders Denmark to the north, Poland and the Czech Republic to the east, Austria and Switzerland to the south, and France, Luxembourg, Belgium, and the Netherlands to the west. The nation's capital and most populous city is Berlin and its financial centre is Frankfurt; the largest urban area is the Ruhr. Various Germanic tribes have inhabited the northern parts of modern Germany since classical antiquity. A region named Germania was documented before AD 100. In 962, the Kingdom of Germany formed the bulk of the Holy Roman Empire. During the 16th ce ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Austria-Hungary
Austria-Hungary, often referred to as the Austro-Hungarian Empire,, the Dual Monarchy, or Austria, was a constitutional monarchy and great power in Central Europe between 1867 and 1918. It was formed with the Austro-Hungarian Compromise of 1867 in the aftermath of the Austro-Prussian War and was dissolved shortly after its defeat in the First World War. Austria-Hungary was ruled by the House of Habsburg and constituted the last phase in the constitutional evolution of the Habsburg monarchy. It was a multinational state and one of Europe's major powers at the time. Austria-Hungary was geographically the second-largest country in Europe after the Russian Empire, at and the third-most populous (after Russia and the German Empire). The Empire built up the fourth-largest machine building industry in the world, after the United States, Germany and the United Kingdom. Austria-Hungary also became the world's third-largest manufacturer and exporter of electric home appliances, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hermann Oberth
Hermann Julius Oberth (; 25 June 1894 – 28 December 1989) was an Austro-Hungarian-born German physicist and engineer. He is considered one of the founding fathers of rocketry and astronautics, along with Robert Esnault-Pelterie, Konstantin Tsiolkovsky, Robert Goddard and Herman Potočnik.During WWII he supported Nazi Germany's ''Aggregat'' rocket program. Early life Oberth was born to a Transylvanian Saxon family in Nagyszeben (Hermannstadt), Austrian-Hungary Empire (today Sibiu in Romania). He was fluent in Romanian language. At the age of 11 years, Oberth's interest in rocketry was set off by the novels of Jules Verne, especially ''From the Earth to the Moon'' and ''Around the Moon''. He was fond of reading them over and over until they were engraved in his memory. As a result, Oberth constructed his first model rocket as a school student at the age of 14. In his youthful experiments, he arrived independently at the concept of the multistage rocket. However, during this ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Propellant
A propellant (or propellent) is a mass that is expelled or expanded in such a way as to create a thrust or other motive force in accordance with Newton's third law of motion, and "propel" a vehicle, projectile, or fluid payload. In vehicles, the engine that expels the propellant is called a reaction engine. Although technically a propellant is the reaction mass used to create thrust, the term "propellant" is often used to describe a substance which is contains both the reaction mass and the fuel that holds the energy used to accelerate the reaction mass. For example, the term "propellant" is often used in chemical rocket design to describe a combined fuel/propellant, although the propellants should not be confused with the fuel that is used by an engine to produce the energy that expels the propellant. Even though the byproducts of substances used as fuel are also often used as a reaction mass to create the thrust, such as with a chemical rocket engine, propellant and fuel are two ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rocket Engine
A rocket engine uses stored rocket propellants as the reaction mass for forming a high-speed propulsive jet of fluid, usually high-temperature gas. Rocket engines are reaction engines, producing thrust by ejecting mass rearward, in accordance with Newton's third law. Most rocket engines use the combustion of reactive chemicals to supply the necessary energy, but non-combusting forms such as cold gas thrusters and nuclear thermal rockets also exist. Vehicles propelled by rocket engines are commonly called rockets. Rocket vehicles carry their own oxidiser, unlike most combustion engines, so rocket engines can be used in a vacuum to propel spacecraft and ballistic missiles. Compared to other types of jet engine, rocket engines are the lightest and have the highest thrust, but are the least propellant-efficient (they have the lowest specific impulse). The ideal exhaust is hydrogen, the lightest of all elements, but chemical rockets produce a mix of heavier species, reducing the e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astronautics
Astronautics (or cosmonautics) is the theory and practice of travel beyond Earth's atmosphere into outer space. Spaceflight is one of its main applications and space science its overarching field. The term ''astronautics'' (originally ''astronautique'' in French) was coined in the 1920s by J.-H. Rosny, president of the Goncourt academy, in analogy with aeronautics. Because there is a degree of technical overlap between the two fields, the term aerospace is often used to describe both at once. In 1930, Robert Esnault-Pelterie published the first book on the new research field. The term ''cosmonautics'' (originally ''cosmonautique'' in French) was introduced in 1930s by Ary Sternfeld with his book ''Initiation à la Cosmonautique'' (Introduction to cosmonautics) (the book brought him the Prix REP-Hirsch, later known as the Prix d'Astronautique, of the French Astronomical Society in 1934.) As with aeronautics, the restrictions of mass, temperatures, and external forces require t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Centroid
In mathematics and physics, the centroid, also known as geometric center or center of figure, of a plane figure or solid figure is the arithmetic mean position of all the points in the surface of the figure. The same definition extends to any object in ''n''-dimensional Euclidean space. In geometry, one often assumes uniform mass density, in which case the ''barycenter'' or ''center of mass'' coincides with the centroid. Informally, it can be understood as the point at which a cutout of the shape (with uniformly distributed mass) could be perfectly balanced on the tip of a pin. In physics, if variations in gravity are considered, then a ''center of gravity'' can be defined as the weighted mean of all points weighted by their specific weight. In geography, the centroid of a radial projection of a region of the Earth's surface to sea level is the region's geographical center. History The term "centroid" is of recent coinage (1814). It is used as a substitute for the older te ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Moment Of Inertia
The moment of inertia, otherwise known as the mass moment of inertia, angular mass, second moment of mass, or most accurately, rotational inertia, of a rigid body is a quantity that determines the torque needed for a desired angular acceleration about a rotational axis, akin to how mass determines the force needed for a desired acceleration. It depends on the body's mass distribution and the axis chosen, with larger moments requiring more torque to change the body's rate of rotation. It is an extensive (additive) property: for a point mass the moment of inertia is simply the mass times the square of the perpendicular distance to the axis of rotation. The moment of inertia of a rigid composite system is the sum of the moments of inertia of its component subsystems (all taken about the same axis). Its simplest definition is the second moment of mass with respect to distance from an axis. For bodies constrained to rotate in a plane, only their moment of inertia about an axis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Center Of Mass
In physics, the center of mass of a distribution of mass in space (sometimes referred to as the balance point) is the unique point where the weighted relative position of the distributed mass sums to zero. This is the point to which a force may be applied to cause a linear acceleration without an angular acceleration. Calculations in mechanics are often simplified when formulated with respect to the center of mass. It is a hypothetical point where the entire mass of an object may be assumed to be concentrated to visualise its motion. In other words, the center of mass is the particle equivalent of a given object for application of Newton's laws of motion. In the case of a single rigid body, the center of mass is fixed in relation to the body, and if the body has uniform density, it will be located at the centroid. The center of mass may be located outside the physical body, as is sometimes the case for hollow or open-shaped objects, such as a horseshoe. In the case of a dist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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