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Spaceflight is the transportation of manned or unmanned spacecraft into and through space. The first man-made object to achieve spaceflight was the German V-2 Rocket during test flights in 1942. The next major milestone was the Russian satellite Sputnik 1 in 1957 which became the first man-made object to orbit the Earth. A key component of spaceflight is the launch, which is the initial thrust to overcome the force of gravity from the surface of the Earth. Once in space, astrodynamics is used to determine the motion of a spacecraft, and spacecraft propulsion is used to control the motion. Spaceflight is a necessary component of space exploration, but also supports activities such launching of telecommunications satellites and space tourism. History of spaceflight The realistic dream of spaceflight dated back to Konstantin Tsiolkovsky, however Tsiolkovsky wrote in Russian, and this was not widely influential outside Russia. Spaceflight became an engineering possibility with the work of Robert H. Goddard's publication in 1919 of his paper 'A Method of Reaching Extreme Altitudes'; where his application of the de Laval nozzle to liquid fuelled rockets gave sufficient power that interplanetary travel became possible. This paper was highly influential on Hermann Oberth and Werner Von Braun, later key players in spaceflight. Reaching space The most commonly used definition of space, at least from the perspective of spacecraft, is everything more than 100km (60 mi) above the Earth's surface. The United States sometimes uses a 50 mile definition. (See Karman line.) One can distinguish between sub-orbital spaceflight and the orbital spaceflight (cf. Difference between sub-orbital and orbital spaceflights). For sub-orbital flights, on October 3, 1942 a German A4 rocket (a prototype for the V2 rocket used to bomb London), became the first successful launch of an object into space. The first organisms launched into space were bacteria trapped aboard the same flight. Another milestone was achieved on May 17, 2004 when Civilian Space eXploration Team launched the GoFast Rocket on a suborbital flight, the first amateur space flight. On June 21, 2004, SpaceShipOne became the first privately-funded manned spacecraft. Achieving a closed orbit is not essential for manned or unmanned interplanetary voyages, where an escape orbit needs to be reached. Early Russian space vehicles successfully achieved very high altitudes without going into orbit. The USA, in its early Apollo mission planning considered using a direct ascent to the moon, but abandoned that idea later due to weight considerations. Many unmanned space probes to the outer planets use direct ascent -- they do not orbit the earth before departing. However, plans for future manned flight often include final vehicle assembly in earth orbit. Because suborbital space flights are by definition short (less than 1.7 hours) any longer mission requires orbital flight (with elliptical or circular trajectory), or superorbital flight (over parabolic or hyperbolic trajectory). However, orbital flight requires much higher velocities than suborbital making it technologically challenging to achieve. Launch pads and Spaceports, takeoff
Reentry and landing/splashdown Orbital vehicles have enough kinetic energy to vapourise the vehicle many times over. This energy must be lost if the vehicle is to land. The theory behind reentry is due to Harry Julian Allen. Based on this theory, reentry vehicles present blunt shapes to the atmosphere for reentry. Blunt shapes mean that less than 1% of the kinetic energy ends up as heat that reaches the vehicle and the heat energy instead ends up in the atmosphere. The Apollo and Mercury capsules landed in the sea. The capsule was designed to land at relatively slow speeds. Russian capsules for Soyuz land on land and use braking rockets. The Space Shuttle glides into a touchdown at high speed. Expendable Launch Systems
Reusable launch systems
Spacecraft Spacecraft are vehicles capable of controlling their trajectory through space. The first 'true spacecraft' is sometimes said to be Apollo Lunar Module since this was the only vehicle to have been designed for, and operated only in space; and is notable for its non aerodynamic shape. Private versus Governmental spaceflight There is growing interest in spacecraft and flights paid for by commercial companies and even private individuals. It is thought that some of the high cost of access to space is due to governmental inefficiencies; and certainly the costs of the governmental paperwork surrounding NASA is legendary. If a commercial company were able to be more efficient costs could come down significantly. Space launch vehicles such as Falcon I have been wholly developed with private finance, and the quoted costs for launch are lower. Zero-gravity
Life support Space disasters Orbital and Sub-orbital spaceflight Interplanetary spaceflight Interstellar spaceflight
Astrodynamics Astrodynamics is the study of spacecraft trajectories, particularly as they relate to gravitational and propulsion effects. Astrodynamics allows for the spacecraft to arrive at their destination at the correct time; without excessive propellant use. Spacecraft propulsion Spacecraft today predominately use rockets for propulsion, but other propulsion techniques such as ion drives are becoming more common, particularly for unmanned vehicles, and this can significantly reduce the vehicle's mass and increase its delta-v. List of spaceflights See: List of spaceflights by year. Also: See also | |||||||||||||||||
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