- Low Earth Orbits
Satellites in low Earth orbits are normally military reconnaissance satellites that can pick out tanks from 160 km above the Earth. They orbit the earth very quickly, one complete orbit normally taking 90 minutes. However, these orbits have very short lifetimes in the order of weeks compared with decades for geostationary satellites. Simple launch vehicles can be used to place these satellites of large masses into orbit.
- Sun-Synchronous orbits
Meteorological satellites are often placed in a sun-synchronous or heliosynchronous orbit. These satellites are in polar orbits. The orbits are designed so that the satellite's orientation is fixed relative to the Sun throughout the year, allowing very accurate weather predictions to be made. Most meteorological satellites orbit the Earth 15 to 16 times per day.
- Geosynchronous satellites
Earth-synchronous or geosynchronous satellites are placed into orbit so that their period of rotation exactly matches the Earth's rotation. They take 24 hours to make one rotation. However, the plane of orbit for these satellites is generally not the equatorial plane. Apart from geostationary satellites (see below), the satellites are used for communications at high latitudes, particularly in Russia and Canada. The orbits are called Molniya orbits. The satellites are placed in highly elliptical orbits which enable them to appear to hover above one point on the Earth for most of the day. In twenty four hours they move over the Earth in a figure of eight pattern centred on a fixed longitude, moving slowly where they can be useful and quickly where they are of little use.
- Geostationary satellites
The majority of communications satellites are in fact geostationary satellites. Geostationary satellites like geosynchronous satellites take 24 hours to complete a rotation. However, geostationary satellites are positioned directly over the equator and their path follows the equatorial plane of the Earth. As a result geostationary satellites don't move North or South during the day and are permanently fixed above one point on the equator of the Earth.
Most video or T.V. communications systems use geostationary satellites. Geosynchronous and geostationary satellites are typically orbiting at 35,788 km (22,238 miles) above the surface of the planet (42,000 km from its centre).
Modern satellites have a mass of several thousand kilograms, compared with just 180 kilograms for Sputnik. Modern satellites are placed in space using launch vehicles like the Arianne Rocket or the Space Shuttle. Once in space, most satellites obtain their power from the Sun using solar panels. Satellites travelling deep into space often carry additional nuclear power supplies.
http://www.telescope.org/nuffield/pas/moon/moon9e.html
2006-12-19 15:14:19
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answer #1
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answered by Anonymous
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guy made up of organic? Planets we could no longer forget approximately the planets in our image voltaic gadget are sattelites around the solar. An occasion the Earth is a sattelite of the solar. Moons are super rocky bodies that are in a defined obrit with a planet. Examples are our moon and Io. Comets are small bodies composed of dirt and ice that trip in the process the image voltaic gadget as they attitude closer to the solar, the suns potential reasons the exterior to soften transforming into the diverse tail. they are in a obrit aroubnd the solar and is additionally considered a sattellite. An occasion is Haleys coment which obrits the solar as quickly as each and every seventy six years. Asteroids additionally noted as "minor planets" are super chunks of rock that orbit the solar. An occasion may be Ceres, yet with maximum of asteroids now being got here upon they are utilising a numbering scheme for all new disceveries. Geostationary Sattelites, are guy made satellies that are positioned right into a "parking orbit" meaning they orbit the earth on the comparable velocity the earth rotates so as that they are consistently interior the comparable region relative to the earths floor. think of direct television and GPS sattelites. different guy-made sattelites, they are literally thousands of alternative guy-made sattelites in fairly some orbits that "circulate" relative to the earths floor. The worldwide area station is in basic terms a sort of.
2016-10-15 06:59:11
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answer #2
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answered by juart 4
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Hi. As an amateur radio operator I'd like to submit one other. Privately funded communication satellites. Some, like AO-40, are in very unusual, but well thought out, orbits.
2006-12-19 15:02:25
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answer #3
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answered by Cirric 7
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Satellites can be divided into five principal types: research, communications, weather, navigational, and applications.
Research satellites measure fundamental properties of outer space, e.g., magnetic fields, the flux of cosmic rays and micrometeorites, and properties of celestial objects that are difficult or impossible to observe from the earth. Early research satellites included a series of orbiting observatories designed to study radiation from the sun, light and radio emissions from distant stars, and the earth's atmosphere. Notable research satellites have included the Hubble Space Telescope, the Compton Gamma-Ray Observatory, the Chandra X-ray Observatory, the Infrared Space Observatory, and the Solar and Heliospheric Observatory (see observatory, orbiting). Also contributing to scientific research were the experiments conducted by the astronauts and cosmonauts aboard the space stations launched by the United States (Skylab) and the Soviet Union (Salyut and Mir); in these stations researchers worked for months at a time on scientific or technical projects. The International Space Station, currently under construction, will continue this work.
Communications satellites provide a worldwide linkup of radio, telephone, and television. The first communications satellite was Echo 1; launched in 1960, it was a large metallized balloon that reflected radio signals striking it. This passive mode of operation quickly gave way to the active or repeater mode, in which complex electronic equipment aboard the satellite receives a signal from the earth, amplifies it, and transmits it to another point on the earth. Relay 1 and Telstar 1, both launched in 1962, were the first active communications satellites; Telstar 1 relayed the first live television broadcast across the Atlantic Ocean. However, satellites in the Relay and Telstar program were not in geosynchronous orbits, which is the secret to continuous communications networks. Syncom 3, launched in 1964, was the first stationary earth satellite. It was used to telecast the 1964 Olympic Games in Tokyo to the United States, the first television program to cross the Pacific Ocean. In principle, three geosynchronous satellites located symmetrically in the plane of the earth's equator can provide complete coverage of the earth's surface. In practice, many more are used in order to increase the system's message-handling capacity. The first commercial geosynchronous satellite, Intelsat 1 (better known as Early Bird), was launched by COMSAT in 1965. A network of 29 Intelsat satellites in geosynchronous orbit now provides instantaneous communications throughout the world. In addition, numerous communications satellites have been orbited by commercial organizations and individual nations for a variety of telecommunications tasks.
Weather satellites, or meteorological satellites, provide continuous, up-to-date information about large-scale atmospheric conditions such as cloud cover and temperature profiles. Tiros 1, the first such satellite, was launched in 1960; it transmitted infrared television pictures of the earth's cloud cover and was able to detect the development of hurricanes and to chart their paths. The Tiros series was followed by the Nimbus series, which carried six cameras for more detailed scanning, and the Itos series, which was able to transmit night photographs. Other weather satellites include the Geostationary Operational Environmental Satellites (GOES), which send weather data and pictures that cover a section of the United States; China, Japan, India, and the European Space Agency have orbited similar craft. Current weather satellites can transmit visible or infrared photos, focus on a narrow or wide area, and maneuver in space to obtain maximum coverage.
Navigation satellites were developed primarily to satisfy the need for a navigation system that nuclear submarines could use to update their inertial navigation system. This led the U.S. navy to establish the Transit program in 1958; the system was declared operational in 1962 after the launch of Transit 5A. Transit satellites provided a constant signal by which aircraft and ships could determine their positions with great accuracy. In 1967 civilians were able to enjoy the benefits of Transit technology. However, the Transit system had an inherent limitation. The combination of the small number of Transit satellites and their polar orbits meant there were some areas of the globe that were not continuously covered—as a result, the users had to wait until a satellite was properly positioned before they could obtain navigational information. The limitations of the Transit system spurred the next advance in satellite navigation: the availability of 24-hour worldwide positioning information. The Navigation Satellite for Time and Ranging/Global Positioning Satellite System (Navstar/GPS) consists of 24 satellites approximately 11,000 miles above the surface of the earth in six different orbital planes. The GPS has several advantages over the Transit system: It provides greater accuracy in a shorter time; users can obtain information 24 hours a day; and users are always in view of at least five satellites, which yields highly accurate location information (a direct readout of position accurate to within a few yards) including altitude. In addition, because of technological improvements, the GPS system has user equipment that is smaller and less complex. The former Soviet Union established a Navstar equivalent system known as the Global Orbiting Navigation Satellite System (GLONASS). GLONASS will use the same number of satellites and orbits similar to those of Navstar when complete. Many of the handheld GPS receivers can also use the GLONASS data if equipped with the proper processing software.
Applications satellites are designed to test ways of improving satellite technology itself. Areas of concern include structure, instrumentation, controls, power supplies, and telemetry for future communications, meteorological, and navigation satellites.
2006-12-19 17:28:34
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answer #4
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answered by jamaica 5
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Satellites can be divided into five principal types: research, communications, weather, navigational, and applications.
--> http://www.infoplease.com/ce6/sci/A0860930.html
2006-12-19 14:38:09
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answer #5
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answered by DanE 7
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