1.
Advanced Extremely High Frequency
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Advanced Extremely High Frequency is a series of communications satellites operated by the United States Air Force Space Command. They will be used to secure communications for the Armed Forces of the United States, the British Armed Forces, the Canadian Forces. The system will consist of six satellites in geostationary orbits, three of which have been launched, AEHF will replace the older Milstar system and will operate at 44 GHz Uplink and 20 GHz Downlink. AEHF systems is a joint service system that will provide survivable, global, secure, protected. It is the follow-on to Milistar system, AEHF systems uplinks and crosslinks will operate in the extremely high frequency range and downlinks in the super high frequency range. AEHF satellites use a number of narrow spot beams directed towards the Earth to relay communications to. Crosslinks between the satellites allow them to relay communications directly rather than via a ground station, the satellites are designed to provide jam-resistant communications with a low probability of interception. They incorporate frequency-hopping radio technology, as well as phased array antennas that can adapt their radiation patterns in order to block out potential sources of jamming. AEHF incorporates the existing Milstar low data-rate and medium data-rate signals and it also incorporates a new signal, allowing data rates of up to 8.192 Mbit/s. When complete, the segment of the AEHF system will consist of six satellites. The contract covered the construction and launch of three satellites, and the construction of a control segment. The contract was managed by the MILSATCOM Program Office of the United States Air Force Space, like the Milstar system, AEHF will be operated by the 4th Space Operations Squadron, located at Schriever Air Force Base. The first satellite, USA-214, was launched by an Atlas V531 rocket on 14 August 2010. This occurred four years behind schedule, when the contract was awarded in 2000 the first launch was expected to occur in 2006. The program was restructured in October 2004, when the National Security Agency did not deliver key cryptographic equipment to the contractor in time to meet the launch schedule. This took much longer than intended due to the lower starting altitude for the HCT maneuvers. This led to delays, as the second and third satellite vehicle LAEs were analyzed. The investigation into the anomaly has been completed and the remaining satellites were declared flight ready
2.
Satellite
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In the context of spaceflight, a satellite is an artificial object which has been intentionally placed into orbit. Such objects are called artificial satellites to distinguish them from natural satellites such as Earths Moon. In 1957 the Soviet Union launched the worlds first artificial satellite, since then, about 6,600 satellites from more than 40 countries have been launched. According to a 2013 estimate,3,600 remained in orbit, of those, about 1,000 were operational, the rest have lived out their useful lives and become space debris. Approximately 500 operational satellites are in orbit,50 are in medium-Earth orbit. A few large satellites have been launched in parts and assembled in orbit. Over a dozen space probes have been placed into orbit around other bodies and become artificial satellites to the Moon, Mercury, Venus, Mars, Jupiter, Saturn, a few asteroids, Satellites are used for many purposes. Common types include military and civilian Earth observation satellites, communications satellites, navigation satellites, weather satellites, Space stations and human spacecraft in orbit are also satellites. Satellite orbits vary greatly, depending on the purpose of the satellite, well-known classes include low Earth orbit, polar orbit, and geostationary orbit. A launch vehicle is a rocket that throws a satellite into orbit, usually it lifts off from a launch pad on land. Some are launched at sea from a submarine or a mobile maritime platform, Satellites are usually semi-independent computer-controlled systems. Satellite subsystems attend many tasks, such as power generation, thermal control, telemetry, attitude control, the first fictional depiction of a satellite being launched into orbit was a short story by Edward Everett Hale, The Brick Moon. The idea surfaced again in Jules Vernes The Begums Fortune, in 1903, Konstantin Tsiolkovsky published Exploring Space Using Jet Propulsion Devices, which is the first academic treatise on the use of rocketry to launch spacecraft. He calculated the speed required for a minimal orbit. In 1928, Herman Potočnik published his book, The Problem of Space Travel — The Rocket Motor. He described the use of orbiting spacecraft for observation of the ground, in a 1945 Wireless World article, the English science fiction writer Arthur C. Clarke described in detail the possible use of communications satellites for mass communications. He suggested that three geostationary satellites would provide coverage over the entire planet, the first artificial satellite was Sputnik 1, launched by the Soviet Union on October 4,1957, and initiating the Soviet Sputnik program, with Sergei Korolev as chief designer. This in turn triggered the Space Race between the Soviet Union and the United States, Sputnik 1 helped to identify the density of high atmospheric layers through measurement of its orbital change and provided data on radio-signal distribution in the ionosphere
3.
Communication channel
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A channel is used to convey an information signal, for example a digital bit stream, from one or several senders to one or several receivers. A channel has a capacity for transmitting information, often measured by its bandwidth in Hz or its data rate in bits per second. Communicating data from one location to another requires some form of pathway or medium and these pathways, called communication channels, use two types of media, cable and broadcast. Cable or wire line media use physical wires of cables to transmit data, twisted-pair wire and coaxial cables are made of copper, and fiber-optic cable is made of glass. In information theory, a channel refers to a theoretical channel model with certain error characteristics, in this more general view, a storage device is also a kind of channel, which can be sent to and received from. Examples of communications include, A connection between initiating and terminating nodes of a circuit. A single path provided by a transmission medium via either physical separation, such as by multipair cable or electrical separation, a path for conveying electrical or electromagnetic signals, usually distinguished from other parallel paths. A storage which can communicate a message over time as well as space The portion of a medium, such as a track or band. A buffer from which messages can be put and got, see Actor model and process calculi for discussion on the use of channels. In a communications system, the physical or logical link that connects a data source to a data sink, a specific radio frequency, pair or band of frequencies, usually named with a letter, number, or codeword, and often allocated by international agreement. Examples, Marine VHF radio uses some 88 channels in the VHF band for two-way FM voice communication, Channel 16, for example, is 156.800 MHz. In the US, seven additional channels, WX1 - WX7, are allocated for weather broadcasts, television channels such as North American TV Channel 2 =55.25 MHz, Channel 13 =211.25 MHz. Each channel is 6 MHz wide, besides these physical channels, television also has virtual channels. Wi-Fi consists of unlicensed channels 1-13 from 2412 MHz to 2484 MHz in 5 MHz steps, the radio channel between an amateur radio repeater and a ham uses two frequencies often 600 kHz apart. For example, a repeater that transmits on 146.94 MHz typically listens for a ham transmitting on 146.34 MHz, all of these communications channels share the property that they transfer information. The information is carried through the channel by a signal, a channel can be modelled physically by trying to calculate the physical processes which modify the transmitted signal. For example, in wireless communications the channel can be modelled by calculating the reflection off every object in the environment, a sequence of random numbers might also be added in to simulate external interference and/or electronic noise in the receiver. Statistical and physical modelling can be combined, for example, in wireless communications the channel is often modelled by a random attenuation of the transmitted signal, followed by additive noise
4.
Transmitter
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In electronics and telecommunications a transmitter or radio transmitter is an electronic device which generates a radio frequency alternating current. When a connected antenna is excited by this current, the antenna emits radio waves. The term transmitter is usually limited to equipment that generates radio waves for communication purposes, or radiolocation, such as radar and navigational transmitters. Generators of radio waves for heating or industrial purposes, such as ovens or diathermy equipment, are not usually called transmitters even though they often have similar circuits. The term is used more specifically to refer to a broadcast transmitter. This usage typically includes both the proper, the antenna, and often the building it is housed in. A transmitter can be a piece of electronic equipment, or an electrical circuit within another electronic device. A transmitter and a receiver combined in one unit is called a transceiver, the term transmitter is often abbreviated XMTR or TX in technical documents. The purpose of most transmitters is radio communication of information over a distance, the transmitter combines the information signal to be carried with the radio frequency signal which generates the radio waves, which is called the carrier signal. The information can be added to the carrier in several different ways, in an amplitude modulation transmitter, the information is added to the radio signal by varying its amplitude. In a frequency modulation transmitter, it is added by varying the signals frequency slightly. Many other types of modulation are used, the radio signal from the transmitter is applied to the antenna, which radiates the energy as radio waves. The antenna may be enclosed inside the case or attached to the outside of the transmitter, as in portable devices such as phones, walkie-talkies. In more powerful transmitters, the antenna may be located on top of a building or on a tower, and connected to the transmitter by a feed line. The first primitive radio transmitters were built by German physicist Heinrich Hertz in 1887 during his investigations of radio waves. These generated radio waves by a high voltage spark between two conductors, beginning in 1895 Guglielmo Marconi developed the first practical radio communication systems using spark transmitters. These spark-gap transmitters were used during the first three decades of radio, called the wireless telegraphy or spark era, vacuum tube transmitters took over because they were inexpensive and produced continuous waves, which could be modulated to transmit audio using amplitude modulation. This made possible commercial AM radio broadcasting, which began in about 1920, experimental television transmission had been conducted by radio stations since the late 1920s, but practical television broadcasting didnt begin until the 1940s
5.
Radio receiver
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In radio communications, a radio receiver is an electronic device that receives radio waves and converts the information carried by them to a usable form. It is used with an antenna, the antenna intercepts radio waves and converts them to tiny alternating currents which are applied to the receiver, and the receiver extracts the desired information. The information produced by the receiver may be in the form of sound, a radio receiver may be a separate piece of electronic equipment, or an electronic circuit within another device. The most familiar form of radio receiver is a broadcast receiver, often just called a radio, the sound is produced either by a loudspeaker in the radio or an earphone which plugs into a jack on the radio. The radio requires electric power, provided either by batteries inside the radio or a cord which plugs into an electric outlet. All radios have a control to adjust the loudness of the audio. The frequency of radio stations is usually listed prominently in their advertising, in order to select a particular station to receive, the radio is adjusted to the frequency of the desired transmitter. In some radios this is done by the user turning a tuning knob until the station is heard in the radios loudspeaker. In most countries radio broadcasting is permitted using two different methods of modulation, that is, methods of adding the signal to the radio wave, AM and FM. In amplitude modulation the strength of the signal is varied by the audio signal. AM broadcasting is permitted on AM broadcast bands between 148 and 283 kHz in the low range and 526 and 1706 kHz in the medium frequency range of the radio spectrum. In frequency modulation the frequency of the signal is varied slightly by the audio signal. FM broadcasting is permitted in the FM broadcast bands between about 65 and 108 MHz in the high frequency range. The exact frequency ranges vary somewhat in different countries, radios sold in each receive the correct frequency range for that country. Most broadcast radios, called AM/FM radios, can receive both AM and FM bands, and have a switch to select which band to receive. Limited AM broadcasting is permitted in parts of the high frequency band called the shortwave band. Shortwave listening requires a receiver that can receive these bands, called a shortwave receiver, at these frequencies, radio waves transmitted into the sky can reflect from a layer in the atmosphere called the ionosphere, returning to earth at transcontinental distances. So shortwaves are used for long distance international broadcasting, often by governmental public service broadcasting organizations like the BBC, due to their lower frequency, AM radio stations can often be received at longer distances than FM stations, at hundreds of miles
6.
Television
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Television or TV is a telecommunication medium used for transmitting moving images in monochrome, or in color, and in two or three dimensions and sound. The term can refer to a set, a television program. Television is a medium for entertainment, education, news, politics, gossip. Television became available in experimental forms in the late 1920s. After World War II, a form of black-and-white TV broadcasting became popular in the United States and Britain, and television sets became commonplace in homes, businesses. During the 1950s, television was the medium for influencing public opinion. In the mid-1960s, color broadcasting was introduced in the US, for many reasons, the storage of television and video programming now occurs on the cloud. At the end of the first decade of the 2000s, digital television transmissions greatly increased in popularity, another development was the move from standard-definition television to high-definition television, which provides a resolution that is substantially higher. HDTV may be transmitted in various formats, 1080p, 1080i, in 2013, 79% of the worlds households owned a television set. Most TV sets sold in the 2000s were flat-panel, mainly LEDs, major manufacturers announced the discontinuation of CRT, DLP, plasma, and even fluorescent-backlit LCDs by the mid-2010s. In the near future, LEDs are gradually expected to be replaced by OLEDs, also, major manufacturers have announced that they will increasingly produce smart TVs in the mid-2010s. Smart TVs with integrated Internet and Web 2.0 functions became the dominant form of television by the late 2010s, Television signals were initially distributed only as terrestrial television using high-powered radio-frequency transmitters to broadcast the signal to individual television receivers. Alternatively television signals are distributed by cable or optical fiber, satellite systems and. Until the early 2000s, these were transmitted as analog signals, a standard television set is composed of multiple internal electronic circuits, including a tuner for receiving and decoding broadcast signals. A visual display device which lacks a tuner is correctly called a video monitor rather than a television, the word television comes from Ancient Greek τῆλε, meaning far, and Latin visio, meaning sight. The Anglicised version of the term is first attested in 1907 and it was. formed in English or borrowed from French télévision. In the 19th century and early 20th century, other. proposals for the name of a technology for sending pictures over distance were telephote. The abbreviation TV is from 1948, the use of the term to mean a television set dates from 1941
7.
Telephone
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A telephone, or phone, is a telecommunications device that permits two or more users to conduct a conversation when they are too far apart to be heard directly. In 1876, Scottish emigrant Alexander Graham Bell was the first to be granted a United States patent for a device that produced clearly intelligible replication of the human voice and this instrument was further developed by many others. The telephone was the first device in history that people to talk directly with each other across large distances. Telephones rapidly became indispensable to businesses, government, and households, the essential elements of a telephone are a microphone to speak into and an earphone which reproduces the voice in a distant location. Until approximately the 1970s most telephones used a dial, which was superseded by the modern DTMF push-button dial. The receiver and transmitter are usually built into a handset which is held up to the ear, the dial may be located either on the handset, or on a base unit to which the handset is connected. The transmitter converts the sound waves to electrical signals which are sent through the network to the receiving phone. The receiving telephone converts the signals into audible sound in the receiver, telephones permit duplex communication, meaning they allow the people on both ends to talk simultaneously. The first telephones were connected to each other from one customers office or residence to another customers location. Being impractical beyond just a few customers, these systems were replaced by manually operated centrally located switchboards. For greater mobility, various systems were developed for transmission between mobile stations on ships and automobiles in the middle 20th century. Hand-held mobile phone]s was introduced for personal service starting in 1973, by the late 1970s several mobile telephone networks operated around the world. In 1983, the Advanced Mobile Phone System was launched, offering a standardized technology providing portability for users far beyond the residence or office. These analog cellular system evolved into digital networks with better security, greater capacity, better regional coverage, the public switched telephone network, with its hierarchical system of many switching centers, interconnects telephones around the world for communication with each other. With the standardized international numbering system, E.164, each line has an identifying telephone number. Although originally designed for voice communications, convergence has enabled most modern cell phones to have many additional capabilities. Since 1999, the trend for mobile phones is smartphones that integrate all mobile communication, a traditional landline telephone system, also known as plain old telephone service, commonly carries both control and audio signals on the same twisted pair of insulated wires, the telephone line. The control and signaling equipment consists of three components, the ringer, the hookswitch, and a dial, the ringer, or beeper, light or other device, alerts the user to incoming calls
8.
Radio
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When radio waves strike an electrical conductor, the oscillating fields induce an alternating current in the conductor. The information in the waves can be extracted and transformed back into its original form, Radio systems need a transmitter to modulate some property of the energy produced to impress a signal on it, for example using amplitude modulation or angle modulation. Radio systems also need an antenna to convert electric currents into radio waves, an antenna can be used for both transmitting and receiving. The electrical resonance of tuned circuits in radios allow individual stations to be selected, the electromagnetic wave is intercepted by a tuned receiving antenna. Radio frequencies occupy the range from a 3 kHz to 300 GHz, a radio communication system sends signals by radio. The term radio is derived from the Latin word radius, meaning spoke of a wheel, beam of light, however, this invention would not be widely adopted. The switch to radio in place of wireless took place slowly and unevenly in the English-speaking world, the United States Navy would also play a role. Although its translation of the 1906 Berlin Convention used the terms wireless telegraph and wireless telegram, the term started to become preferred by the general public in the 1920s with the introduction of broadcasting. Radio systems used for communication have the following elements, with more than 100 years of development, each process is implemented by a wide range of methods, specialised for different communications purposes. Each system contains a transmitter, This consists of a source of electrical energy, the transmitter contains a system to modulate some property of the energy produced to impress a signal on it. This modulation might be as simple as turning the energy on and off, or altering more subtle such as amplitude, frequency, phase. Amplitude modulation of a carrier wave works by varying the strength of the signal in proportion to the information being sent. For example, changes in the strength can be used to reflect the sounds to be reproduced by a speaker. It was the used for the first audio radio transmissions. Frequency modulation varies the frequency of the carrier, the instantaneous frequency of the carrier is directly proportional to the instantaneous value of the input signal. FM has the capture effect whereby a receiver only receives the strongest signal, Digital data can be sent by shifting the carriers frequency among a set of discrete values, a technique known as frequency-shift keying. FM is commonly used at Very high frequency radio frequencies for high-fidelity broadcasts of music, analog TV sound is also broadcast using FM. Angle modulation alters the phase of the carrier wave to transmit a signal
9.
Internet
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The Internet is the global system of interconnected computer networks that use the Internet protocol suite to link devices worldwide. The origins of the Internet date back to research commissioned by the United States federal government in the 1960s to build robust, the primary precursor network, the ARPANET, initially served as a backbone for interconnection of regional academic and military networks in the 1980s. Although the Internet was widely used by academia since the 1980s, Internet use grew rapidly in the West from the mid-1990s and from the late 1990s in the developing world. In the two decades since then, Internet use has grown 100-times, measured for the period of one year, newspaper, book, and other print publishing are adapting to website technology, or are reshaped into blogging, web feeds and online news aggregators. The entertainment industry was initially the fastest growing segment on the Internet, the Internet has enabled and accelerated new forms of personal interactions through instant messaging, Internet forums, and social networking. Business-to-business and financial services on the Internet affect supply chains across entire industries, the Internet has no centralized governance in either technological implementation or policies for access and usage, each constituent network sets its own policies. The term Internet, when used to refer to the global system of interconnected Internet Protocol networks, is a proper noun. In common use and the media, it is not capitalized. Some guides specify that the word should be capitalized when used as a noun, the Internet is also often referred to as the Net, as a short form of network. Historically, as early as 1849, the word internetted was used uncapitalized as an adjective, the designers of early computer networks used internet both as a noun and as a verb in shorthand form of internetwork or internetworking, meaning interconnecting computer networks. The terms Internet and World Wide Web are often used interchangeably in everyday speech, however, the World Wide Web or the Web is only one of a large number of Internet services. The Web is a collection of interconnected documents and other web resources, linked by hyperlinks, the term Interweb is a portmanteau of Internet and World Wide Web typically used sarcastically to parody a technically unsavvy user. The ARPANET project led to the development of protocols for internetworking, the third site was the Culler-Fried Interactive Mathematics Center at the University of California, Santa Barbara, followed by the University of Utah Graphics Department. In an early sign of growth, fifteen sites were connected to the young ARPANET by the end of 1971. These early years were documented in the 1972 film Computer Networks, early international collaborations on the ARPANET were rare. European developers were concerned with developing the X.25 networks, in December 1974, RFC675, by Vinton Cerf, Yogen Dalal, and Carl Sunshine, used the term internet as a shorthand for internetworking and later RFCs repeated this use. Access to the ARPANET was expanded in 1981 when the National Science Foundation funded the Computer Science Network, in 1982, the Internet Protocol Suite was standardized, which permitted worldwide proliferation of interconnected networks.5 Mbit/s and 45 Mbit/s. Commercial Internet service providers emerged in the late 1980s and early 1990s, the ARPANET was decommissioned in 1990
10.
Military
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The armed forces of a country are its government-sponsored defense, fighting forces, and organizations. They exist to further the foreign and domestic policies of their body and to defend that body. Armed force is the use of armed forces to achieve political objectives, the study of the use of armed forces is called military science. Broadly speaking, this involves considering offense and defense at three levels, strategy, operational art, and tactics, all three levels study the application of the use of force in order to achieve a desired objective. In most countries the basis of the forces is the military. However, armed forces can include other paramilitary structures, the obvious benefit to a country in maintaining armed forces is in providing protection from foreign threats and from internal conflict. In recent decades armed forces personnel have also used as emergency civil support roles in post-disaster situations. On the other hand, they may harm a society by engaging in counter-productive warfare. Expenditure on science and technology to develop weapons and systems sometimes produces side benefits, although some claim that greater benefits could come from targeting the money directly
11.
Electromagnetic radiation
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In physics, electromagnetic radiation refers to the waves of the electromagnetic field, propagating through space carrying electromagnetic radiant energy. It includes radio waves, microwaves, infrared, light, ultraviolet, X-, classically, electromagnetic radiation consists of electromagnetic waves, which are synchronized oscillations of electric and magnetic fields that propagate at the speed of light through a vacuum. The oscillations of the two fields are perpendicular to other and perpendicular to the direction of energy and wave propagation. The wavefront of electromagnetic waves emitted from a point source is a sphere, the position of an electromagnetic wave within the electromagnetic spectrum can be characterized by either its frequency of oscillation or its wavelength. Electromagnetic waves are produced whenever charged particles are accelerated, and these waves can interact with other charged particles. EM waves carry energy, momentum and angular momentum away from their source particle, quanta of EM waves are called photons, whose rest mass is zero, but whose energy, or equivalent total mass, is not zero so they are still affected by gravity. Thus, EMR is sometimes referred to as the far field, in this language, the near field refers to EM fields near the charges and current that directly produced them, specifically, electromagnetic induction and electrostatic induction phenomena. In the quantum theory of electromagnetism, EMR consists of photons, quantum effects provide additional sources of EMR, such as the transition of electrons to lower energy levels in an atom and black-body radiation. The energy of a photon is quantized and is greater for photons of higher frequency. This relationship is given by Plancks equation E = hν, where E is the energy per photon, ν is the frequency of the photon, a single gamma ray photon, for example, might carry ~100,000 times the energy of a single photon of visible light. The effects of EMR upon chemical compounds and biological organisms depend both upon the power and its frequency. EMR of visible or lower frequencies is called non-ionizing radiation, because its photons do not individually have enough energy to ionize atoms or molecules, the effects of these radiations on chemical systems and living tissue are caused primarily by heating effects from the combined energy transfer of many photons. In contrast, high ultraviolet, X-rays and gamma rays are called ionizing radiation since individual photons of high frequency have enough energy to ionize molecules or break chemical bonds. These radiations have the ability to cause chemical reactions and damage living cells beyond that resulting from simple heating, Maxwell derived a wave form of the electric and magnetic equations, thus uncovering the wave-like nature of electric and magnetic fields and their symmetry. Because the speed of EM waves predicted by the wave equation coincided with the speed of light. Maxwell’s equations were confirmed by Heinrich Hertz through experiments with radio waves, according to Maxwells equations, a spatially varying electric field is always associated with a magnetic field that changes over time. Likewise, a varying magnetic field is associated with specific changes over time in the electric field. In an electromagnetic wave, the changes in the field are always accompanied by a wave in the magnetic field in one direction
12.
Arthur C. Clarke
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Sir Arthur Charles Clarke, CBE, FRAS was a British science fiction writer, science writer and futurist, inventor, undersea explorer, and television series host. He is perhaps most famous for being co-writer of the screenplay for the 1968 film 2001, A Space Odyssey, Clarke was a science writer, who was both an avid populariser of space travel and a futurist of uncanny ability. On these subjects he wrote over a dozen books and many essays, in 1961 he was awarded the Kalinga Prize, an award which is given by UNESCO for popularizing science. These along with his fiction writings eventually earned him the moniker Prophet of the Space Age. His other science fiction writings earned him a number of Hugo and Nebula awards, for many years Clarke, Robert Heinlein and Isaac Asimov were known as the Big Three of science fiction. Clarke was a proponent of space travel. In 1934, while still a teenager, he joined the British Interplanetary Society, in 1945, he proposed a satellite communication system, an idea which won him the Franklin Institutes Stuart Ballantine Medal in 1963, and other honours. Later he was the chairman of the British Interplanetary Society from 1946–47, Clarke emigrated from England to Sri Lanka in 1956, largely to pursue his interest in scuba diving. That year he discovered the ruins of the ancient Koneswaram temple in Trincomalee. Clarke augmented his fame later on in the 1980s, from being the host of television shows such as Arthur C. He lived in Sri Lanka until his death and he was knighted in 1998 and was awarded Sri Lankas highest civil honour, Sri Lankabhimanya, in 2005. Clarke was born in Minehead, Somerset, England, and grew up in nearby Bishops Lydeard, as a boy, he grew up on a farm enjoying stargazing, fossil collecting, and reading American science fiction pulp magazines. He received his education at Huish Grammar school in Taunton. Early influences included dinosaur cigarette cards, which led to an enthusiasm for fossils starting about 1925, in his teens, he joined the Junior Astronomical Association and contributed to Urania, the societys journal, which was edited in Glasgow by Marion Eadie. At Clarkes request, she added an Astronautics Section, which featured a series of articles by him on spacecraft and he moved to London in 1936 and joined the Board of Education as a pensions auditor. Clarke spent most of his wartime service working on ground-controlled approach radar, as documented in the semi-autobiographical Glide Path, although GCA did not see much practical use during the war, it proved vital to the Berlin Airlift of 1948–1949 after several years of development. Clarke initially served in the ranks, and was an instructor on radar at No.2 Radio School. He was commissioned as an officer on 27 May 1943
13.
Konstantin Tsiolkovsky
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Konstantin Eduardovich Tsiolkovsky was a Russian and Soviet rocket scientist and pioneer of the astronautic theory. Along with the French Robert Esnault-Pelterie, the German Hermann Oberth and his works later inspired leading Soviet rocket engineers such as Sergei Korolev and Valentin Glushko and contributed to the success of the Soviet space program. Tsiolkovsky spent most of his life in a log house on the outskirts of Kaluga, a recluse by nature, he appeared strange and bizarre to his fellow townsfolk. He was born in Izhevskoye, in the Russian Empire, to a middle-class family and his father, Edward Tsiolkovsky, was a Polish-born Russian Orthodox, his mother, Maria Ivanovna Yumasheva belonged to Russian nobility of Volga Tatar origin. His father was successively a forester, teacher, and minor government official, at the age of 10, Konstantin caught scarlet fever and became hard of hearing. When he was 13, his mother died and he was not admitted to elementary schools because of his hearing problem, so he was self-taught. As a reclusive home-schooled child, he passed much of his time by reading books, as a teenager, he began to contemplate the possibility of space travel. After falling behind in his studies, Tsiolkovsky spent three years attending a Moscow library where Russian cosmism proponent Nikolai Fyodorov worked and he later came to believe that colonizing space would lead to the perfection of the human race, with immortality and a carefree existence. Additionally, inspired by the fiction of Jules Verne, Tsiolkovsky theorized many aspects of space travel and he is considered the father of spaceflight and the first person to conceive the space elevator, becoming inspired in 1895 by the newly constructed Eiffel Tower in Paris. Afterwards, Tsiolkovsky passed the exam and went to work at a school in Borovsk near Moscow. He also met and married his wife Varvara Sokolovaya during this time, despite being stuck in Kaluga, a small town far from major learning centers, Tsiolkovsky managed to make scientific discoveries on his own. The first two decades of the 20th century were marred by personal tragedy, Tsiolkovskys son Ignaty committed suicide in 1902, and in 1908 many of his accumulated papers were lost in a flood. In 1911, his daughter Lyubov was arrested for engaging in revolutionary activities and this section has recently been partly machine translated from the Russian article. Please supply an improved translation if possible, Tsiolkovsky stated that he developed the theory of rocketry only as a supplement to philosophical research on the subject. He wrote more than 400 works including approximately 90 published pieces on space travel, Tsiolkovskys first scientific study dates back to 1880–1881. Undaunted, he pressed ahead with his work, The Mechanics of the Animal Organism. It received favorable feedback, and Tsiolkovsky was made a member of the Society, in 1892, he was transferred to a new teaching post in Kaluga where he continued to experiment. Tsiolkovsky developed the first aerodynamics laboratory in Russia in his apartment, in 1897, he built the first Russian wind tunnel with an open test section and developed a method of experimentation using it
14.
Electronics World
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Electronics World is a technical magazine in electronics and RF engineering aimed at professional design engineers. It is produced monthly in print and digital formats and it encompasses a range of issues in the electronics and RF industry, from design through to product implementation. The features are contributed by engineers and academics in the electronics industry, the Marconi Company published the first issue of the journal The Marconigraph in April 1911. This monthly magazine was the first significant journal dedicated to wireless communication, in April 1913, after two years and 24 issues, The Marconigraph was superseded by The Wireless World. An Illustrated Monthly Magazine for all interested in Wireless Telegraphy and Telephony as its first issue was sold on news-stands, with the same issue, publication frequency of Wireless World became weekly. A similar series was published after 1945 utilising the then ubiquitous EF50 RF pentode amplifier valve, with the outbreak of World War II and the expected shortages of paper and other resources, the publication reverted to being monthly, a frequency that it still retains to this day. The title was changed in September 1984 to Electronics and Wireless World, a sister publication was Wireless Engineer which was more of a learned journal than a popular magazine, featuring high quality, technical articles. In October 1945 Wireless World published what became a famous article by Arthur C. Clarke which foresaw the coming of communications satellites in synchronous orbit around the Earth. In his Wireless World article Clarke suggested that three satellites placed in the equatorial orbit at an altitude of 36,000 km, spaced 120 degrees apart. In 1962 NASA launched Telstar 1, the first communications satellite, Telstar 1 lasted only six months, but this paved the way for modern-day communications-there are nearly 900 active satellites in orbit today of which some two-thirds are communications satellites. Clarkes article, Extra-Terrestrial Relays, was Electronic World readers most asked for article to re-print in the centenary edition. The article was featured in the BBCs The Genius of Invention programme broadcast on 7 February 2013. For decades, Wireless World was a place where pioneers in audio, in 1952 it made the first public announcement of the Baxandall tone control circuit, a design now employed in millions of hi-fi systems including amplifiers and effects for musical instruments. In 1955 it published the design of the popular Mullard 5-10 audio amplifier using two EL84 power pentodes in ultra-linear push-pull configuration, in 1975/6 Wireless World published the design of a decoder of broadcast TV Teletext information before the first commercial decoder became available. Later it published regular columns of brief Circuit Ideas, in the August to December 1967 editions a series, Wireless World Digital Computer by Brian Crank, was published. It described how to build a simple binary computer at home. It was constructed entirely from reject transistors, and was intended for teaching the principles of computer operation. In 1977 a series of articles was published based on the design of the NASCOM1 computer, in 1979 they published a design by John Adams for a dual-processor desktop computer which included a novel high-level programming language
15.
Invention
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An invention is a unique or novel device, method, composition or process. The invention process is a process within an overall engineering and product development process and it may be an improvement upon a machine or product or a new process for creating an object or a result. An invention that achieves a unique function or result may be a radical breakthrough. Such works are novel and not obvious to others skilled in the same field, an inventor may be taking a big step in success or failure. A patent legally protects the property rights of the inventor. The rules and requirements for patenting an invention vary from country to country, another meaning of invention is cultural invention, which is an innovative set of useful social behaviours adopted by people and passed on to others. The Institute for Social Inventions collected many such ideas in magazines, Invention is also an important component of artistic and design creativity. Inventions often extend the boundaries of knowledge, experience or capability. Brainstorming also can spark new ideas for an invention, collaborative creative processes are frequently used by engineers, designers, architects and scientists. Co-inventors are frequently named on patents, in addition, many inventors keep records of their working process - notebooks, photos, etc. including Leonardo da Vinci, Galileo Galilei, Evangelista Torricelli, Thomas Jefferson and Albert Einstein. In the process of developing an invention, the idea may change. The invention may become simpler, more practical, it may expand, working on one invention can lead to others too. History shows that turning the concept of an invention into a device is not always swift or direct. Inventions may also more useful after time passes and other changes occur. For example, the became more useful once powered flight was a reality. Invention is often a creative process, an open and curious mind allows an inventor to see beyond what is known. Seeing a new possibility, connection, or relationship can spark an invention, inventive thinking frequently involves combining concepts or elements from different realms that would not normally be put together. Sometimes inventors disregard the boundaries between distinctly separate territories or fields, several concepts may be considered when thinking about invention
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Communication Moon Relay
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The Communication Moon Relay project was a telecommunication project carried out by the United States Navy. Its objective was to develop a secure and reliable method of communication by using the Moon as a natural communications satellite - a technique known as EME communications. Most of the work took place during the 1950s at the United States Naval Research Laboratory. Operation Moon Relay was spun off from a military espionage program known as Passive Moon Relay which sought to eavesdrop on Soviet military radar signals reflected from the Moon. Communication Moon Relay grew out of ideas and concepts in radio espionage. Some impetus for the project was provided by post-World War II efforts to develop methods of tracking radio signals, particularly those originating in Eastern Europe, other sources included earlier proposals to use the Moon as a radio wave reflector, which date back to 1928. The first proof of concept was the Project Diana program of the U. S. Army Signal Corps in 1946. This attracted the attention of Donald Menzel, before artificial satellites, the Moon provided the only reliable celestial object from which to reflect radio waves to communicate between points on opposite sides of the Earth. The developments in Moon circuit communications eventually came to the attention of James Trexler and his interest was piqued by a paper published by researchers at an ITT laboratory. Trexler developed plans for a designed to intercept Soviet radar signals by detecting the transmissions that bounced off the Moon. This program, codenamed Joe, began making observations in August 1949. Within a year, Joe was made an official Navy intelligence program, in September 1950, a new parabolic antenna for the PAMOR project was completed at Stump Neck, Maryland. The first tests of this antenna were impressive, the signal was of much higher fidelity than expected. This presented the possibility of using a Moon circuit as a communications circuit, unfortunately for PAMOR, collecting Soviet radar signals would require a larger antenna. Efforts began to have such an antenna constructed at Sugar Grove, with the PAMOR project requiring a larger antenna, the Stump Neck antenna was pushed into service for testing whether communication via the Moon was possible. This marked the emergence of the Moon Relay as a separate project, test transmissions between Stump Neck and Washington, DC were carried out, the first satellite transmission of voice occurred on July 24,1954. These were followed by the first transcontinental test of the system on November 20,1955, after corrections to reduce signal loss, the transmissions were extended to Wahiawa, Hawaii. The Navy received the new system favorably, a Navy contract for the project soon followed the successful tests, and, among other things, it was recommended that American submarines use Moon-reflection paths for communications to shore
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Sputnik 1
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Sputnik 1 was the first artificial Earth satellite. The Soviet Union launched it into an elliptical low Earth orbit on 4 October 1957 and it was a 58 cm diameter polished metal sphere, with four external radio antennas to broadcast radio pulses. It was visible all around the Earth and its radio pulses were detectable and this surprise success precipitated the American Sputnik crisis and triggered the Space Race, a part of the larger Cold War. The launch ushered in new political, military, technological, tracking and studying Sputnik 1 from Earth provided scientists with valuable information, even though the satellite itself wasnt equipped with sensors. The density of the atmosphere could be deduced from its drag on the orbit. Sputnik 1 was launched during the International Geophysical Year from Site No. 1/5, at the 5th Tyuratam range, the satellite travelled at about 29,000 kilometres per hour, taking 96.2 minutes to complete each orbit. It transmitted on 20.005 and 40.002 MHz, the signals continued for 21 days until the transmitter batteries ran out on 26 October 1957. Sputnik burned up on 4 January 1958 while reentering Earths atmosphere, after travelling about 70 million km, on 17 December 1954, chief Soviet rocket scientist Sergei Korolev addressed Dimitri Ustinov and proposed a developmental plan for an artificial satellite. Korolev forwarded a report by Mikhail Tikhonravov with an overview of similar projects abroad, Tikhonravov had emphasized that the launch of an orbital satellite was an inevitable stage in the development of rocket technology. On 29 July 1955, U. S. President Dwight D. Eisenhower announced through his press secretary that the United States would launch an artificial satellite during the International Geophysical Year. A week later, on 8 August, the Politburo of the Communist Party of the Soviet Union approved the proposal to create an artificial satellite. On 30 August Vasily Ryabikov – the head of the State Commission on R-7 rocket test launches – held a meeting where Korolev presented calculation data for a trajectory to the Moon. They decided to develop a version of the R-7 rocket for satellite launches. On 30 January 1956 the Council of Ministers approved practical work on an artificial Earth-orbiting satellite. This satellite, named Object D, was planned to be completed in 1957–58, it would have a mass of 1,000 to 1,400 kg, the first test launch of Object D was scheduled for 1957. These included measuring the density of the atmosphere and its ion composition, the wind, magnetic fields. These data would be valuable in the creation of artificial satellites. A system of stations was to be developed to collect data transmitted by the satellite, observe the satellites orbit
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Soviet Union
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The Soviet Union, officially the Union of Soviet Socialist Republics was a socialist state in Eurasia that existed from 1922 to 1991. It was nominally a union of national republics, but its government. The Soviet Union had its roots in the October Revolution of 1917 and this established the Russian Socialist Federative Soviet Republic and started the Russian Civil War between the revolutionary Reds and the counter-revolutionary Whites. In 1922, the communists were victorious, forming the Soviet Union with the unification of the Russian, Transcaucasian, Ukrainian, following Lenins death in 1924, a collective leadership and a brief power struggle, Joseph Stalin came to power in the mid-1920s. Stalin suppressed all opposition to his rule, committed the state ideology to Marxism–Leninism. As a result, the country underwent a period of rapid industrialization and collectivization which laid the foundation for its victory in World War II and postwar dominance of Eastern Europe. Shortly before World War II, Stalin signed the Molotov–Ribbentrop Pact agreeing to non-aggression with Nazi Germany, in June 1941, the Germans invaded the Soviet Union, opening the largest and bloodiest theater of war in history. Soviet war casualties accounted for the highest proportion of the conflict in the effort of acquiring the upper hand over Axis forces at battles such as Stalingrad. Soviet forces eventually captured Berlin in 1945, the territory overtaken by the Red Army became satellite states of the Eastern Bloc. The Cold War emerged by 1947 as the Soviet bloc confronted the Western states that united in the North Atlantic Treaty Organization in 1949. Following Stalins death in 1953, a period of political and economic liberalization, known as de-Stalinization and Khrushchevs Thaw, the country developed rapidly, as millions of peasants were moved into industrialized cities. The USSR took a lead in the Space Race with Sputnik 1, the first ever satellite, and Vostok 1. In the 1970s, there was a brief détente of relations with the United States, the war drained economic resources and was matched by an escalation of American military aid to Mujahideen fighters. In the mid-1980s, the last Soviet leader, Mikhail Gorbachev, sought to reform and liberalize the economy through his policies of glasnost. The goal was to preserve the Communist Party while reversing the economic stagnation, the Cold War ended during his tenure, and in 1989 Soviet satellite countries in Eastern Europe overthrew their respective communist regimes. This led to the rise of strong nationalist and separatist movements inside the USSR as well, in August 1991, a coup détat was attempted by Communist Party hardliners. It failed, with Russian President Boris Yeltsin playing a role in facing down the coup. On 25 December 1991, Gorbachev resigned and the twelve constituent republics emerged from the dissolution of the Soviet Union as independent post-Soviet states
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Project Echo
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Project Echo was the first passive communications satellite experiment. Each of the two American spacecraft, launched in 1960 and 1964, was a balloon satellite acting as a passive reflector of microwave signals. Communication signals were bounced off them from one point on Earth to another. )NASAs Echo 1 satellite was built by Gilmore Schjeldahls G. T. Schjeldahl Company in Northfield, Minnesota. The balloon satellite functioned as a reflector, not a transceiver, so after it was placed in a low Earth orbit a signal could be sent to it, reflected by its surface, and returned to Earth. During ground inflation tests,40,000 pounds of air was needed to fill the balloon, at launch the balloon weighed 156.995 pounds which included 33.34 pounds of sublimating powders of two types. The first weighing 10 pounds with a high vapor pressure. The first attempt to orbit an Echo satellite miscarried when Echo 1 lifted from Cape Canaverals LC-17A on the morning of May 13,1960. The Thor performed properly, but during the phase, the attitude control jets on the unproven Delta stage failed to ignite. The satellite also aided the calculation of atmospheric density and solar pressure due to its large area-to-mass ratio, as its shiny surface was also reflective in the range of visible light, Echo 1A was easily visible to the unaided eye over most of the Earth. The spacecraft was nicknamed a satelloon by those involved in the project and it also had 107.9 MHz beacon transmitters for telemetry purposes, powered by five nickel-cadmium batteries that were charged by 70 solar cells mounted on the balloon. During the latter portion of its life, the spacecraft was used to evaluate the feasibility of satellite triangulation. It had a mass of 180 kilograms. Echo 2 was a 41. 1-meter-diameter balloon, which was the last balloon satellite launched by Project Echo and it used an improved inflation system to improve the balloons smoothness and sphericity. It was launched January 25,1964, on a Thor Agena rocket.00005 mm of mercury and 0.5 mm of mercury, especially during the initial inflation stages. The system consisted of two beacon assemblies powered by solar panels and had a minimum power output of 45 mW at 136.02 MHz and 136.17 MHz. In addition to the passive communications experiments, it was used to investigate the dynamics of large spacecraft, Echo 2, being larger than Echo 1A and also orbiting in a near polar orbit, was conspicuously visible to the unaided eye over all of the Earth. Echo 2 reentered Earths atmosphere and burned up on June 7,1969, unlike Echo 1, Echo 2s skin was rigidizable, and the balloon was capable of maintaining its shape without a constant internal pressure. This removed the requirement for a long term supply of inflation gas, the balloon was constructed from a 0. 35mil thick mylar film sandwiched between two layers of 0.18 mil thick aluminum foil and bonded together
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BoPET
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A variety of companies manufacture boPET and other polyester films under different brand names. In the UK and US, the most well-known trade names are Mylar, Melinex, BoPET film was developed in the mid-1950s, originally by DuPont, Imperial Chemical Industries and Hoechst. In 1964, NASA launched Echo II and it was a 40 m diameter balloon constructed from a 0. 35mil thick mylar film sandwiched between two layers of 0.18 mil thick aluminum foil and bonded together. The manufacturing process begins with a film of polyethylene terephthalate being extruded onto a chill roll. It is then biaxially oriented by drawing and it is also possible to draw the film in both directions simultaneously, although the equipment required for this is somewhat more elaborate. Draw ratios are typically around 3 to 4 in each direction, once the drawing is completed, the film is heat set or crystallized under tension in the oven at temperatures typically above 200 °C. The heat setting step prevents the film from shrinking back to its original unstretched shape, the orientation of the polymer chains is responsible for the high strength and stiffness of biaxially oriented PET film, which has a typical Youngs modulus of about 4 GPa. Another important consequence of the orientation is that it induces the formation of many crystal nuclei. The crystallites that grow rapidly reach the boundary of the neighboring crystallite, as a result, biaxially oriented PET film has excellent clarity, despite its semicrystalline structure. To make handling possible, microscopic inert inorganic particles are embedded in the PET to roughen the surface of the film. Biaxially oriented PET film can be metallized by vapor deposition of a film of evaporated aluminium, gold. The result is less permeable to gases and reflects up to 99% of light. For some applications like food packaging, the aluminized boPET film can be laminated with a layer of polyethylene, the polyethylene side of such a laminate appears dull and the PET side shiny. Other coatings, such as indium tin oxide, can be applied to boPET film by sputter deposition. Uses for boPET polyester films include, but are not limited to, Laminates containing metallized boPET foil protect food against oxidation and aroma loss, examples are coffee foil packaging and pouches for convenience foods. White boPET web substrate is used as lidding for dairy goods such as yogurt, clear boPET web substrate is used as lidding for fresh or frozen ready meals. Due to its excellent heat resistance, it can remain on the package during microwave or oven heating, for protecting the spine of important documents, such as medical records. Metallized boPET film emergency blankets conserve a shock victims body heat, as a thin strip to form an airtight seal between the control surfaces and adjacent structure of aircraft, especially gliders
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Passive repeater
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Compared to a microwave radio relay station with active components, a passive repeater is far simpler and needs little maintenance and no on-site electric power. It also does not require additional frequencies, unlike active repeater stations which use different transmit, the corresponding disadvantage is that without amplification the returned signal is significantly weaker. The resulting structure resembles a billboard, similar systems are used also occasionally for TV relay transmitters or as tunnel transmitters. In these cases, a Yagi antenna receives the transmitted signal and supplies it by way of a coaxial cable to a second Yagi antenna
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SCORE (satellite)
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Project SCORE was the world’s first communications satellite. It captured world attention by broadcasting a Christmas message via short wave radio from U. S. President Dwight D. Eisenhower through a tape recorder. The satellite was popularly dubbed The Talking Atlas, SCORE, as a geopolitical strategy, placed the United States at an even technological par with the Soviet Union as a highly functional response to the Sputnik 1 and Sputnik 2 satellites. The overall project was conducted in secrecy that only 88 people were aware of its existence. Before the date of the SCORE launch,53 of the 88 people had told the project had been canceled. The night before launch, however, Rear Adm, John E. Clark and he replied, No, and news reports that day suggested the voice might well be the presidents. The payload weighed 68 kg, and was built into the pods of the Atlas missile. Combined weight of the total package was 3969 kg. SCORE was launched into a 183 km by 1,481 km orbit from LC-11 at Cape Canaveral Missile Test Annex, Florida inclined 32.3 degrees and its batteries lasted 12 days and it reentered the atmosphere on 21 January 1959. The communications repeater installed on the missile would receive a signal, amplify it, two redundant sets of equipment were mounted in the nose of the SCORE missile. Four antennas were mounted flush with the surface, two for transmission and two for reception. SCOREs other equipment included two tape recorders, each with a four-minute capacity, any of four ground stations in the southern United States could command the satellite into playback mode to transmit the stored message or into record mode to receive and store a new message. These redundancies proved invaluable as one of the tape recorders malfunctioned and was rendered inoperable during the 12-day mission, the first transmitted message from space to Earth was, This is the President of the United States speaking. Through the marvels of scientific advance, my voice is coming to you from a satellite circling in outer space. My message is a one, Through this unique means I convey to you and to all mankind, Americas wish for peace on Earth. The broadcast signal for Eisenhowers greeting was fairly weak, and only very sensitive radio receivers were able to detect it, most Americans heard the message as it was rebroadcast on commercial news programs. List of communications satellite firsts Project Echo
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Dwight D. Eisenhower
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Dwight David Ike Eisenhower was an American politician and Army general who served as the 34th President of the United States from 1953 until 1961. He was a general in the United States Army during World War II. He was responsible for planning and supervising the invasion of North Africa in Operation Torch in 1942–43, in 1951, he became the first Supreme Commander of NATO. Eisenhower was of mostly Pennsylvania Dutch ancestry and was raised in a family in Kansas by parents with a strong religious background. He graduated from West Point in 1915 and later married Mamie Doud, after World War II, Eisenhower served as Army Chief of Staff under President Harry S. Truman and then accepted the post of President at Columbia University. Eisenhower entered the 1952 presidential race as a Republican to counter the non-interventionism of Senator Robert A. Taft, campaigning against communism, Korea and he won in a landslide, defeating Democratic candidate Adlai Stevenson and temporarily upending the New Deal Coalition. Eisenhower was the first U. S. president to be constitutionally term-limited under the 22nd Amendment, Eisenhowers main goals in office were to keep pressure on the Soviet Union and reduce federal deficits. He ordered coups in Iran and Guatemala, Eisenhower gave major aid to help the French in the First Indochina War, and after the French were defeated he gave strong financial support to the new state of South Vietnam. Congress agreed to his request in 1955 for the Formosa Resolution, after the Soviet Union launched Sputnik in 1957, Eisenhower authorized the establishment of NASA, which led to the space race. During the Suez Crisis of 1956, Eisenhower condemned the Israeli, British and French invasion of Egypt and he also condemned the Soviet invasion during the Hungarian Revolution of 1956 but took no action. Eisenhower sent 15,000 U. S. troops to Lebanon to prevent the government from falling to a Nasser-inspired revolution during the 1958 Lebanon crisis. Near the end of his term, his efforts to set up a meeting with the Soviets collapsed because of the U-2 incident. On the domestic front, he covertly opposed Joseph McCarthy and contributed to the end of McCarthyism by openly invoking executive privilege and he otherwise left most political activity to his Vice President, Richard Nixon. Eisenhower was a conservative who continued New Deal agencies and expanded Social Security. Eisenhowers two terms saw considerable economic prosperity except for a decline in 1958. Voted Gallups most admired man twelve times, he achieved widespread popular esteem both in and out of office, since the late 20th century, consensus among Western scholars has consistently held Eisenhower as one of the greatest U. S. Presidents. The Eisenhauer family migrated from Karlsbrunn in the Saarland, to North America, first settling in York, Pennsylvania, in 1741, accounts vary as to how and when the German name Eisenhauer was anglicized to Eisenhower. Eisenhowers Pennsylvania Dutch ancestors, who were farmers, included Hans Nikolaus Eisenhauer of Karlsbrunn
