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Double rocket
Rocket is a kind of jet propulsion device, which uses hot air to jet backward at high speed and uses the generated reaction force to push forward. Usually the word rocket also includes missiles, spaceships and even fireworks. The most common rockets burn solid or liquid chemical propellants. Propellant combustion produces hot gas, which is sprayed to the tail of the rocket through the nozzle. Rockets bring their own fuel and oxidant, while other jet engines only need to carry fuel, and the oxygen needed for fuel combustion is taken from air. Therefore, rockets can be used outside the earth's atmosphere, while other jet engines cannot. When the rocket is launched, it generates huge thrust, which makes the rocket rise into the sky quickly in a short time. With the continuous reduction of fuel, the mass of the rocket itself is gradually reduced. As the distance from the earth increases, the influence of mass and gravity decreases, and the rocket speed becomes faster and faster. When Saturn V rocket set off for the moon, five engines consumed nearly 3 tons of kerosene per second, and the thrust they generated was equivalent to the takeoff thrust of 32 Boeing 747s. It is impossible to determine the exact time when the rocket was invented. Most experts believe that China people developed practical military rockets as early as13rd century. /kloc-there were several technological advances in the 0/9th century: the paper shell of fuel container was changed to metal shell, which prolonged the duration of combustion; Formulation standardization of gunpowder propellant: creating a launch pad; Discovered the principle of spin orientation and so on. At the end of 19, rockets began to be used for non-military purposes, such as transporting lifeline to ships in distress at sea. 19 At the end of the 20th century, American scientist Goddard and several other experts laid the foundation of modern rocket technology and launched the first liquid fuel rocket. In 1970s, the United States developed a brand-new rocket-powered spacecraft-the space shuttle. It is mainly divided into three parts: an orbiter with three main engines at the back of the fuselage; External fuel tank, filled with liquid hydrogen and liquid oxygen propellant (falling off after 5 minutes), to ensure the main engine to work; It is equipped with two separable solid fuel rocket engines (separated after 2 minutes), which are started at the same time as the main engine of the orbiter to provide thrust during the initial lift-off. 1981April 12, the first space shuttle "Columbia" was launched.
Rocket is an aircraft propelled by the reaction force generated by the rocket engine spraying working fluid. It has its own combustion agent and oxidant, and does not rely on oxygen in the air for combustion. It can fly in the atmosphere and outer space. With the consumption of rocket propellant in flight, the rocket mass is decreasing, and it is a variable mass flying body. Modern rockets can be used as fast and long-distance transportation tools, such as sounding, launching satellites, manned spacecraft, space stations, boosters of other aircraft and so on. If it is used to drop combat warheads (warheads), it constitutes a rocket weapon. Among them, guided missiles and unguided rockets are called.
The brief history rocket originated in China and is one of the great inventions of ancient China. The invention and use of gunpowder in ancient China created conditions for the invention of rockets. The popular "meteor" (hereinafter referred to as "fire") in the late Northern Song Dynasty is to use the reaction force of gunpowder gas. According to its working principle, fireworks such as "Meteor" are the earliest rockets used for viewing in the world. During the Southern Song Dynasty, military rockets appeared no later than the middle of12nd century. By the early Ming dynasty, military rockets had been quite perfect and used on the battlefield, and they were called "sharp weapons in the army." The Dragon Array in the early Ming Dynasty and Wu Beizhi in the late Ming Dynasty recorded in detail the production and use of ancient Chinese rockets. Wu Beizhi alone recorded more than 20 kinds of gunpowder rockets, among which the "Fire Dragon Out of the Water" rocket was the prototype of the second-class rocket.
After China's ancient rocket technology was introduced to Europe, rockets were once classified as military equipment after improvement. Early rockets had short range and wide distribution of impact points, and were later replaced by artillery. After World War I, with the continuous progress of science and technology, rocket weapons developed rapidly and played a powerful role in World War II.
/kloc-at the end of 0/9 and the beginning of the 20th century, liquid rocket technology began to rise. 1903, к E tsiolkovsky of Russia put forward the idea and design principle of manufacturing large liquid rockets. 1926, American rocket expert and physicist R.H. Goddard flew the first uncontrolled liquid rocket. 1944, Germany used a controlled V-2 missile propelled by a liquid rocket engine for the first time in the war. After World War II, the Soviet Union and the United States successively developed various rocket weapons, including intercontinental ballistic missiles.
China has been developing new rockets since 1950s. 1970 On April 24th, the first artificial earth satellite was successfully launched by the Long March 1 three-stage carrier rocket. 1 975165438+1On October 26th, the Long March II carrier rocket launched a recoverable heavy satellite with greater thrust (Figure1). 1980 On May 18, a new rocket was successfully launched into the South Pacific. 1982, 10, the submarine successfully launched the rocket underwater. 1On April 8th, 984, the geosynchronous test communication satellite was successfully launched by cz-3 (Figure II) with the third-stage liquid hydrogen and liquid oxygen rocket engine. 1On September 7th, 988, a meteorological satellite was successfully put into sun-synchronous orbit by cz-4 (Figure 3). 1992 August 14, the newly developed Long March II E-type high-thrust carrier rocket launched the Australian Aarseth B 1 satellite into the predetermined orbit. All these indicate that China, as the birthplace of rockets, has entered the advanced ranks in the world in the field of modern rocket technology, and has steadily entered the international launch service market.
In the development of modern rocket technology, Qian Xuesen of China, Braun of the United States and korolev of the Soviet Union all made outstanding contributions.
Rockets can be classified in different ways. According to different energy sources, it can be divided into chemical rockets, nuclear rockets, electric rockets and photon rockets. Chemical rockets are divided into liquid propellant rockets, solid propellant rockets and solid-liquid mixed propellant rockets. According to different purposes, it can be divided into satellite launch vehicles, mine-laying rockets, meteorological rockets, hail suppression rockets and various military rockets. According to whether there is control or not, it can be divided into controlled rockets and uncontrolled rockets. According to the series, it is divided into single-stage rockets and multi-stage rockets. According to the range, it is divided into short-range rockets, medium-range rockets and long-range rockets. Although there are many classification methods for rockets, their components and working principles are basically the same.
The basic components of a rocket are propulsion system, arrow body and payload. The controlled rocket is also equipped with a guidance system.
Rocket propulsion system is the power source of rocket flight. Among them, the fire rocket engine can be divided into chemical rocket engine, nuclear rocket engine, electric rocket engine and photon rocket engine according to its working medium. Chemical rocket engines are widely used, and the energy released by the chemical reaction of propellant in the combustion chamber is converted into thrust. The ratio of thrust to propellant consumption per second is called specific impulse, which is the main index of engine performance, and its level is related to the design and manufacturing level of the engine, but mainly depends on the performance of the selected propellant. The thrust of rocket engine is selected according to its characteristics and uses, and its size varies greatly, as small as micro-cattle, such as electric rocket engine; As big as ten trillion cattle, such as the solid rocket booster of the American space shuttle.
For the controlled rocket, in order to ensure the rocket to accurately guide the target, it is also equipped with a guidance system. The guidance system controls the movement and rotation around the center of mass (pitch, yaw and roll), and guides the rocket to the target stably and accurately. The improvement of guidance system and the continuous improvement of guidance accuracy are a major feature of rocket technology development.
The arrow body is used to install and connect various rocket systems and hold propellant. In addition to a good aerodynamic shape, the arrow body also requires that the lighter the weight, the smaller the volume, the better, while the established function remains unchanged. When the take-off mass is constant and the structural mass is light, a larger flight speed or range can be obtained.
The payload of a launch vehicle includes a satellite, a spacecraft or a space probe. The payload of a rocket weapon is a warhead.
In order to successfully launch a rocket, it is also necessary to have ground launch equipment and launch facilities. Ground launch equipment is large and small. Small portable shoulders, such as the launcher of portable air defense rockets and anti-tank rockets; If it is large, such as a satellite launch vehicle, it needs a fixed launch site and huge launch facilities, as well as a flight tracking and control station.
Present situation and development trend Since 1950s, rocket technology has been rapidly developed and widely used, especially various controllable rocket weapons (missiles) and space launch vehicles. From rockets to anti-tank missiles, air defense missiles, anti-ship missiles, and various tactical missiles and strategic missiles that attack fixed targets on the ground, they have developed to a fairly perfect level and become indispensable weapons for modern troops. All kinds of rocket weapons are developing in the direction of improving hit accuracy, anti-jamming ability, penetration ability and survivability. In addition, rocket weapons such as anti-missile and anti-satellite are also under development. Launch vehicles developed on the basis of ground-to-ground ballistic missiles have been widely used to launch satellites, manned spacecraft and other spacecraft. In the early 1980s, the Soviet Union and the United States developed six or seven series of launch vehicles respectively. Among them, the Saturn V rocket manned by the United States to the moon has a diameter of 10 m, a length of11m, a takeoff mass of about 2,930 tons, and a low-earth orbit carrying capacity of 127 tons. The take-off mass of the Soviet "Energy" rocket is about 2,000 tons, and the carrying capacity in low earth orbit is about 100 tons. China's Long March II E rocket (Figure 5) adopts parallel booster technology, which not only improves the carrying capacity, but also lays the foundation for further developing rockets with greater carrying capacity. The launch vehicle is developing towards high reliability, low cost, multi-purpose and multi-purpose. The appearance of the space shuttle, which can travel back and forth between space and the earth many times, is the embodiment of this development trend. The rapid development of rocket technology can not only provide more perfect missiles and promote the development of related science, but also make it possible to develop space resources, establish space industry, space base and interstellar navigation.
Three satellites
1. a star orbiting a planet, such as the moon as a satellite of the earth.
The abbreviation of artificial earth satellite is widely used.
1On April 24th, 970, the first artificial earth satellite "Dongfanghong-1" designed and manufactured by China was successfully launched by the Long March-1 carrier rocket. The orbit of the satellite is 439 kilometers from the nearest point of the earth and 2384 kilometers from the farthest point. The angle between the orbital plane and the equatorial plane of the earth is 68.5 degrees, and it takes 1 14 minutes to circle the earth. The satellite weighs 173 kg and plays the music of Dongfanghong at a frequency of 20009 megacycles. It has fulfilled the call of President Mao Zedong that "we should also build artificial satellites". China is a star of science and an outstanding contribution made by the working class, the People's Liberation Army and intellectuals in China to the motherland.
Since 1957, when the Soviet Union put the world's first artificial satellite into orbit around the earth, humans have launched a large number of aircraft into the vast universe. The latest worldwide satellite database recently released by an American organization called "Union of Worried Scientists" shows that there are 795 satellites in Earth orbit, more than half of which belong to the United States, the only superpower in the world, and the number of satellites it owns has exceeded the sum of all other countries, reaching 4 13, and the number of military satellites has reached more than a quarter.
four-dimensional space
The whole space except the air space. International law recognizes that a country has a certain height of airspace above its territory, and that country has complete and exclusive sovereignty over it. Therefore, the airspace of a country generally refers to the airspace above its territory, and the outer space is the space outside the airspace. With the development of natural science, outer space law has become an integral part of international law.
Physicists divide the atmosphere into five layers: troposphere (sea level to 10km), stratosphere (10 ~ 40km), mesosphere (40 ~ 80km), thermosphere (ionosphere, 80 ~ 370km) and outer atmosphere (ionosphere, over 370km). About 3/4 of the atmosphere above the earth is in the troposphere, and 97% is below the stratosphere. The outer edge of the stratosphere is the highest limit for an aircraft to fly with air support. Some high-altitude rockets can enter the middle layer. The lowest orbit of the satellite is in the thermocline, and its air density is 1% of the earth's surface. At the height of 16000km, air continues to exist, and even at the height of 10000km, there are still air particles. From a strictly scientific point of view, there is no clear boundary between airspace and outer space, but they are gradually integrated. The Scientific and Technical Subcommittee of the United Nations Committee on the Peaceful Uses of Outer Space pointed out that it is impossible to put forward accurate and lasting scientific standards to divide the boundary between outer space and airspace. In recent years, people tend to take the minimum height of artificial satellites from the ground (100 ~110) km as the lowest limit of outer space.
In international law, although some scholars have put forward the viewpoint of infinite airspace, it is of no practical significance to think that national sovereignty extends into the universe indefinitely because of the rotation and revolution of the earth and the movement of the whole solar system. The exploration and utilization of outer space and the fact that thousands of artificial satellites are constantly orbiting the earth show that outer space is difficult to be controlled by national sovereignty in essence. 1963 The Declaration on Legal Principles for the Activities of States in the Exploration and Use of Outer Space adopted by the United Nations General Assembly established two principles: outer space is free for all countries to explore and use, and it is forbidden for any country to occupy it.
The United Nations Committee on the Peaceful Uses of Outer Space (COPUOS) was established as a permanent body in 1959. COPUOS has set up two subcommittees, namely, law and science and technology, to consider and study relevant legal and scientific issues respectively. In addition to the above-mentioned declaration adopted by the General Assembly in 1963, COPUOS has also drafted five international treaties on outer space, namely, the Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, including the Moon and Other Celestial Bodies (1966, referred to as the Outer Space Treaty for short) and Rescue of Astronauts, Return of Astronauts and Return of Launches into Outer Space.