Translated by BabelFish
The STS (Space Transportation System, for system of space transport), whose NASA ensures the implementation, are the first reusable system of launching which was ever carried out by the man. The studies concerning this system, which go up at the years 1967-1968, led to an important meeting, held in 1969, during which about thirty technical studies relating to a space shuttle were examined. The first configuration chosen for the future American space plane was connected with that of a seaplane equipped with a low and right aerofoil. It yielded the place to a delta without tail in 1970, but of the budgetary restrictions forced the technicians to reduce the size of the apparatus. The bulky inboard tanks in which hydrogen and oxygen were to be stored liquidate were eliminated then replaced by an external tank. The anaerobic engines being abandoned, the Orbiter shuttle was to penetrate in the Earth's atmosphere and to land without system of propulsion, which made of it the heaviest sailplane never carried out. This way of proceeding as well as the elimination of the capsule of rescue intended for the crew made it possible to increase the payload notably.
In January 1972, president Nixon approved the project STS which, by making it possible to multiply in important proportions the number of missions ensured by the same launcher, made it possible to reduce in an appreciable way the cost of each ton placed in orbit. In the middle of the Eighties, the aforementioned cost represented half of that of a conventional launcher, and, in so far as it is known, the US Air Force paid the same price as any civil customer of NASA.
Of the important markets had passed in 1972-1973, Rockwell being in charge of the development Orbiter shuttle, Morton Thiokol of the rocket engines with powder and Martin-Marietta of the oxygen and liquid hydrogen tanks. Each rocket engine with powder has a 45,46 m length, weighs 586 050 kg and provides a push of 1 497 000 kg. The conduit of this element is directional in order to allow a control of the trajectory of flight during the first phase of launching. The hydraulic systems which order the orientation of each conduit are connected to the electric control device of flight by the means of the autopilot. The rocket engines with powder cease functioning two minutes after the departure then are ejected by eight engines of separation of 10 000 kgp (4 with before and 4 with the back). They deadened in their fall by a parachute of stabilization then by a brake chute in three elements. Once recovered in the ocean, the rocket engines are given to new in order to being able to be re-used for the following shooting (their lifespan is estimated at a score of launchings). The fuel tank contains, as for him, 617 775 kg of liquid oxygen and 103 255 kg of liquid hydrogen. Because of the very low density of this last product, the hydrogen tank is bulkier than that in which oxygen is stored. The complete unit, which is perfectly isolated in order to avoid any escape, reached the total mass of 750 980 kg. Released with the approximate altitude of 110 km, little time before the placing in orbit, that is to say 8 minutes after launching, it is not recoverable.
the three rocket engines which equip the shuttle, due to Rockwell Rocketdyne Division, are fed by oxygen and hydrogen liquidate coming from the tank described above. They can be directly ordered since the cockpit and can be used during fifty-five successive flights. The push that they provide to the sea level, i.e. at the time of launching, is 189 290 kg; it reaches 232 245 kg in the space vacuum. One of the principal characteristics of these engines is their very high pressure of operation, which is 3 190 kg/cm2 in the pump with hydrogen and 1 475 kg/cm2 on the level of the combustion chamber. The realization of these machines constituted one of the principalespremière time in the history of humanity that such a power was requested from an engine.
On its side, the space shuttle Orbiter is presented as a delta without tail at the rather squat forms with leading edges rounded and flattened lower surfaces. The cell was partly carried out by Grumman (with regard to the wings) and by General Dynamics/Convair (for the fuselage). It was machined out of aluminium alloys, each wing being equipped with two elevons. Fairchild Republic developed the vertical stabilizer which comprises a rudder of which the two elements are used as air-brakes when they are open. Space between the wings and the elevons is careened by Inconel and titanium panels (alloys the neaux one of titanium and Inconel (nickel alloys) resistant to the very high temperatures.
Whole the remainder of the cell, except for the windshield of the cockpit, are covered with a thermal protection, in fact of the tiles made to resist constraints and important temperatures. The leading edges and the nose of the shuttle are machined out of carbon fibre in order to tolerate temperatures of 1 430 °C at the time of the return in the atmosphere.
the compartment reserved to the crew is composed of three levels. The higher level, that of the cockpit of piloting, has a double order. That of the medium includes/understands three seats, of the benches, of the toilets, a kitchen, compartments with electronics components and the tight door which carries out to the freight compartment. On mission of rescue, the benches can be replaced by three additional seats. Lastly, the third level, low, shelters the system of air conditioning and space necessary to the arrangement of the businesses of the crew.
the Orbiter shuttle were conceived to put a load of 29 485 kg on an orbit at 185 km of the Earth, or a load of 14 515 kg in polar orbit, or a load of 11 340 kg to 500 km of altitude. The payload, which can be very diversified according to the led missions, is stored in large a 18,29 m length central compartment whose diameter reaches 4,57 Mr. This compartment is equipped with two doors in sandwiches of honeycomb theepoxy one, and it comprises an arm manipulator with front, on the left (a second arm can be set up in the event of need on the right). The aforementioned arm is equipped with a camera of television. Several other cameras were installed, of which one colors, in the cockpit of piloting, allowing the control of the load.
In space, To orbit it offer the possibility of being controlled by a whole of rocket engines of weak push. With the back of this aircraft are two subsystems of orbital operation (WHO, for Orbital Manoeuvring Subsystem) of 2 720 kgp each one, using fuels and the combustive special ones. They are used to place To orbit it on high orbits. The subsystem of order is composed of thirty-eight engines of 395 kgp and two others of 11 kgp, all manufactured by Marquardt and burning the same products as WHO. The electric generator is supplied by three fuel tanks in which are stored liquid oxygen and hydrogen. The electric control device of flight of the shuttle, which is quadruplexé, was carried out by Honeywell.
the development of the STS were since the beginning the business of NASA, the shootings being carried out since the space center Kennedy, located at Cape Canaveral. As for the landings, they are held in Edwards AFB, from where the shuttles are brought back to the Kennedy base. The majority of the loads carried until now had a specifically civil destination, either for NASA itself, or for scientific or commercial organizations. Some of the flights of the shuttle had a direction more properly military. The US Air Force built its own center of test in Vandenberg AFB, in California. This base is equipped to allow shootings in high and polar orbits, for the surveillance missions. One of the surfaces of test of Vandenberg, that which is located more at the south, was carried out at the beginning for the shootings of rockets Titan III. The complex placed more at north, as for him, was reserved for the shootings of Minuteman III.
Having a system such as Space Transportation System, the US Air Force started, initially, by withdrawing service its launchers consumable. In a fundamental speech made in January 1985, the president of the United States, Ronald Reagan, decided in favour of an increase in means in the Air Force as regards STS and announced the nearest evaluation of space shuttles of new generation to the capacities much more important. He also let know that the Americans were going to continue to use consumable launchers, in particular rockets Titan 34D-7 and booster rockets much more powerful, within the framework of the initiative of strategic defense.
During recent years, the program of the American space shuttle knew many vicissitudes. In January 1986, indeed, the Challenger shuttle was lost, with seven astronauts on his board, at the time of the explosion, little after the beginning of the shooting, the booster rockets which propelled it towards space. The survey carried out after this serious accident which traumatisé the United States showed many deficiencies of the system and certain deficiencies or imprudences of the manufacturers implied in the program. The delay taken by the Americans compared to the Soviets in the race with space, following this true catastrophe, all the more grew hollow that the shootings of rockets carried out thereafter almost showed all failures. One needed a general and major reconsideration program so that a new attempt can be undertaken under maximum conditions of safety. The Americans had to wait, to arrive to such results, nearly thousand days. The Discovery shuttle thus could take the air on September 29, 1988 with for mission the placing in orbit of satellite TDRSS-3. This first mission, which succeeded perfectly, proceeded in accordance with the forecasts. The very same day where Discovery left the ground, the American Secretary of State George Shultz signed an agreement with NASA concerning the space station Freedom, that the United States intends to set up in the more or less near future.