This repository provides access to more than years of research publications, such as journal articles, conference papers, books and reports. Some records may have full-text attachments available where copyright and confidentiality conditions permit Example Domain. This domain is for use in illustrative examples in documents. You may use this domain in literature without prior coordination or asking for permission This is a list of all companies currently operating at least one commercial communication satellite or currently has one on order. Top 20 [ edit ] Main article: Comparison of communication satellite
List of communication satellite companies - Wikipedia
In the context of spaceflighta satellite is an object that has been intentionally placed into orbit. These objects are called artificial satellites to distinguish them from natural satellites such as Earth's Moon. On 4 Octoberthe Soviet Union launched the world's first artificial satellite, Sputnik 1, research articles in satellite communication. Since then, about 8, satellites from more than 40 countries have been launched.
According to a estimate, about 5, remained in orbit. Of those, about 1, research articles in satellite communication, were operational, while the rest had exceeded their useful lives and become space debris. In terms of countries with the most satellites, the United States has the most with 1, satellites, China is second withand Russia third with Over a dozen space probes have been placed into orbit around other bodies and become artificial satellites of the MoonMercuryVenusMarsJupiterSaturna few asteroids[2] a comet and the Sun.
Satellites are used for many purposes. Among several other applications, they can be used to make star maps and maps of planetary surfacesand also take pictures of planets they are launched into. Common types include military and civilian Earth observation satellitescommunications satellitesnavigation satellitesweather satellitesand space telescopes. Space stations and human spacecraft in orbit are also satellites.
Satellites can operate by themselves or as part of a larger system, a satellite formation or satellite constellation. Satellite orbits vary greatly, depending on the purpose of the satellite, and are classified in a number of ways. Well-known overlapping classes include low Earth orbit, polar orbitand geostationary orbit. A launch vehicle is a rocket that places a satellite into orbit. Usually, it lifts off from a launch pad on land, research articles in satellite communication.
Some are launched at sea from a submarine or a mobile maritime platformor aboard a plane see air launch to orbit. Satellites are usually semi-independent computer-controlled systems. Satellite subsystems attend many tasks, such as power generation, thermal controltelemetry, attitude controlscientific instrumentation, communicationetc, research articles in satellite communication.
The first published mathematical study of the possibility of an artificial satellite was Newton's cannonballresearch articles in satellite communication, a thought experiment by Isaac Newton to explain the motion of natural satellitesin his Philosophiæ Naturalis Principia Mathematica The first fictional depiction of a satellite being launched into orbit was a short story by Edward Everett Hale" The Brick Moon " Inresearch articles in satellite communication, Konstantin Tsiolkovsky — published Exploring Research articles in satellite communication Using Jet Propulsion Deviceswhich is the first academic treatise on the use of rocketry to launch spacecraft.
He calculated the orbital speed required for a minimal orbit, and that a multi-stage rocket fueled by liquid propellants could achieve this. InHerman Potočnik — published his sole book, The Problem of Space Travel — The Rocket Motor, research articles in satellite communication. He described the use of orbiting spacecraft for observation of the ground and described how the special conditions of space could be useful for scientific experiments.
In a Wireless World article, the English science fiction research articles in satellite communication Arthur C. Clarke described in detail the possible use of communications satellites for mass communications.
In Maythe United States Air Force 's Project RAND released the Preliminary Design of an Experimental World-Circling Spaceshipresearch articles in satellite communication, which stated that "A satellite vehicle with appropriate instrumentation can be expected to be one of the most potent scientific tools of the Twentieth Century.
Project RAND eventually released the report, but considered the satellite to be a tool for science, politics, research articles in satellite communication, and propaganda, rather than a potential military weapon, research articles in satellite communication. In research articles in satellite communication, American theoretical astrophysicist Lyman Spitzer proposed an orbiting space telescope. In February Project RAND released "Scientific Uses for a Satellite Vehicle", written by R.
Kallmann and W. In the context of activities planned for the International Geophysical Year —58the White House announced on 29 July that the U. intended to launch satellites by the spring of This became known as Project Vanguard. On 31 July, the Soviets announced that they intended to launch a satellite by the fall of The first artificial satellite was Sputnik 1launched by the Soviet Union on 4 October under the Sputnik programwith Sergei Korolev as chief designer.
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.
The unanticipated announcement of Sputnik 1's success precipitated the Sputnik crisis in the United States and ignited the so-called Space Race within the Cold War. Sputnik 2 was launched on 3 November and carried the first living passenger into orbit, a dog named Laika.
In earlyfollowing pressure by the American Rocket Societythe National Science Foundationand the International Geophysical Year, the Army and Navy were working on Project Orbiter with two competing programs.
Explorer 1 became the United States' first artificial satellite on 31 Research articles in satellite communication In Research articles in satellite communicationthree-and-a-half years after the launch of Sputnik 1, research articles in satellite communication, the United States Space Surveillance Network cataloged Earth-orbiting satellites.
Early satellites were constructed to unique designs. With advancements in technology, multiple satellites began to be built on single model platforms called satellite buses. The first standardized satellite bus design was the HS geosynchronous GEO communication satellite launched in Beginning inFreeFlyer is a commercial off-the-shelf software application for satellite mission analysis, design and operations.
Currently the largest artificial satellite ever is the International Space Station. The United States Space Surveillance Network SSNa division of the United States Strategic Commandhas been tracking objects in Earth's orbit since when the Soviet Union opened the Space Age with the launch of Sputnik I.
Since then, the SSN has tracked more than 26, objects. The SSN currently tracks more than 8,artificial orbiting objects. The rest have re-entered Earth's atmosphere and disintegrated, or survived re-entry and impacted the Earth. The SSN tracks objects that are 10 centimeters in diameter or larger; those now orbiting Earth range from satellites weighing several tons to pieces of spent rocket bodies weighing only 10 pounds.
About seven percent are operational satellites i. There are three basic categories of non-military satellite services: [16].
Fixed satellite services handle hundreds of billions of voice, data, and video transmission tasks across all countries and continents between certain points on the Earth's surface. Scientific research satellites provide meteorological information, land survey data e. remote sensingAmateur HAM Radio, and other different scientific research applications such as earth science, marine science, and atmospheric research.
The first satellite, Sputnik 1was put into orbit around Earth and was therefore in geocentric orbit. This is the most common type of orbit by far, with approximately 3, [19] active artificial satellites orbiting the Earth. Geocentric orbits may be further classified by their altitude, inclination and eccentricity.
The commonly used altitude classifications of geocentric orbit are Low Earth orbit LEOMedium Earth orbit MEO and High Earth orbit HEO.
Low Earth orbit is any orbit below 2, km. Medium Earth orbit is any orbit between 2, and 35, km. High Earth orbit is any orbit higher than 35, km.
The satellite's functional versatility is embedded within its technical components and its operations characteristics. Looking at the "anatomy" of a typical satellite, one discovers two modules. The bus module consists of the following subsystems:. The structural subsystem provides the mechanical base structure with adequate stiffness to withstand stress and vibrations experienced during launch, maintain structural integrity and stability while on station in orbit, and shields the satellite from extreme temperature changes and micro-meteorite damage.
The power subsystem may consist of solar panels to convert solar energy into electrical power, regulation and distribution functions, and batteries that store power and supply the satellite when it passes into the Earth's shadow.
Nuclear power sources Radioisotope thermoelectric generator have also been used in several successful satellite programs including the Nimbus program — The thermal control subsystem helps protect electronic equipment from extreme temperatures due to intense sunlight or the lack of sun exposure on different sides of the satellite's body e. optical solar reflector. The attitude and orbit control subsystem consists of sensors to measure vehicle orientation, control laws research articles in satellite communication in the flight software, and actuators reaction wheels, thrusters.
These apply the torques and forces needed to re-orient the vehicle to the desired attitude, keep the satellite in the correct orbital position, and keep antennas pointed in the right directions. The second major module is the communication payload, which is made up of transponders. A transponder is capable of :. When satellites reach the end of their mission this normally occurs within 3 or 4 years after launchsatellite operators have the option of de-orbiting the satellite, leaving the satellite in its current orbit or moving the satellite to a graveyard orbit.
Historically, due to budgetary constraints at the beginning of satellite missions, satellites were rarely designed to be de-orbited. One example of this practice is the satellite Research articles in satellite communication 1. Launched inVanguard 1the 4th artificial satellite to be put in Geocentric orbit, was still in orbit as of March [update]as well as the upper stage of its launch rocket.
Instead of being de-orbited, most satellites are either left in their current orbit or moved to a graveyard orbit. The nominal breakup altitude due to aerodynamic forces and temperatures is 78 km, with a range between 72 and 84 km. Solar panels, however, are destroyed before any other component at altitudes between 90 and 95 km. This list includes countries with an independent capability to place satellites in orbit, including production of the necessary launch vehicle. Note: many more countries have the capability to design and build satellites but are unable to launch them, instead relying on foreign launch services.
This list does not consider those numerous countries, but only lists those capable of launching satellites indigenously, and the date this capability was first demonstrated. The list does not include the European Space Agencya multi-national state organization, nor private consortiums.
Orbital Sciences Corporation launched a satellite into orbit on the Pegasus in SpaceX launched a satellite into orbit on the Falcon 1 in Rocket Lab launched three cubesats into orbit on the Electron in While Canada was the third country to build a satellite which was launched into space, [32] it was launched aboard an American rocket from an American spaceport.
The same goes for Australia, who launched first satellite involved a donated U. Redstone rocket and American support staff as well as a joint launch facility with the United Kingdom. Scout rocket research articles in satellite communication Wallops Island Virginia, United States with an Italian launch team trained by NASA.
Since the mids, satellites have been hacked by militant organizations to broadcast propaganda and to pilfer classified information from military communication networks.
For testing purposes, satellites in low earth orbit have been destroyed by ballistic missiles launched from earth. RussiaUnited StatesChina and India have demonstrated research articles in satellite communication ability to eliminate satellites.
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Despite mandates by the federal government to ensure inclusion of women and minorities in all federally funded research, 1 African Americans continue to participate less frequently than Whites. Lower participation rates among African Americans have been reported across various study types (e.g., controlled clinical treatment trials, 2,3 intervention trials, 4,5 as well as studies on various This repository provides access to more than years of research publications, such as journal articles, conference papers, books and reports. Some records may have full-text attachments available where copyright and confidentiality conditions permit Energetic Communication. The first biomagnetic signal was demonstrated in by Gerhard Baule and Richard McFee in a magnetocardiogram (MCG) that used magnetic induction coils to detect fields generated by the human heart. [] A remarkable increase in the sensitivity of biomagnetic measurements has since been achieved with the introduction of the superconducting quantum
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