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What do satellites do?
"Natural Satellites" Circle around larger, more massive objects (the Earth is technically a satellite of the Sun, and the Moon is a natural satellite of the Earth). Artific…ial Satellites Satellites orbit the Earth to provide links between places on the planet (TV, phone, internet) and to study the Earth and space. They provide information to the military, to weather forecasting, to geologists, and more. The orbiting space telescopes examine other planets and stars. Satellites orbit in a variety of directions, but most circle west-tp-east at various heights above the Earth's atmosphere. Geostationary satellites seem to stay in one place, but they only in very high orbits. Geosynchronous satellites orbit exactly once a day, so they stay over the same location on the ground. (see related question) .
Communications - This includes television,phones (cellular as well as others), and internet. Satellitetelevision providers, for example, broadcast a one-way signal withaudio and video programming to their customers. This is of greatuse for customers who are in areas too remote to use cable or otherwired means, or for mobile users in vehicles and boats. Customerssimply tune their in-home receivers to the sub-channel they desireand watch digital programming direct from space. .
Earth Observation andSurveillance - Military reconnaissance satellites andcivilian mapping satellites use high-resolution cameras to takephotos of the earth's surface for mapping or intelligence purposes.Further, these cameras are not limited to the visible lightspectrum, and so some are dedicated to infrared or ultravioletsensing, which are used by environmental researchers andagriculturists; this can help them determine the temperature,quantity of foliage, chemical composition of the air in differentlocales, changing height of the polar ice caps, shoreline erosion,or mapping of warm and cold ocean currents. Other uses includepopular web applications, surveying, real-time weather observation,and natural resource detection and management. .
Navigation - Global Positioning System (GPS)satellites function by emitting a specific signal pattern.Variations in this signal can be detected by GPS receivers todetermine a GPS user's location relative to the satellite by usinga principle called the Doppler Effect. The Doppler effect is theapparent compression or decompression of signals that occurs whenthe signal source is in motion, relative to a listener, forexample, why a train whistle changes pitch when it approaches ordeparts from the listener. By calculating the amount of compressionin the signals for multiple satellites, a GPS receiver can pinpointthe user's location. Because of the large distance between satellites, distances fromEarth to distant stars and planets can be determined moreaccurately (greater parallax). Also, on board cameras can betterview objects on Earth in 3 dimensions. There are many purposes for placing satellites in orbit. First andforemost, communications satellites exploit their great distancefrom the earth to transmit their signals the greatest distancepossible. Many modes of communication, chief among them microwave,travel by 'line of sight,' meaning that one must be in a direct,unobstructed sight line in order to receive a signal. The earliestcommunications satellite received and relayed microwavecommunications from large ground stations. Today, we havetechnology to communicate directly through such satellites usingsatellite phones. Satellite communication permits directcommunication beyond the horizon that might not otherwise bepossible with conventional VHF (Very High Frequency) communication(ie, radio). Still other satellites are used for assorted experimental purposes,exploiting the lack of vibration, low temperature and low gravityof space as an ideal location for extremely sensitive instruments,such as the Hubble Space telescope and similar projects, which areable to see much deeper and more clearly into the cosmos withouthaving to look through the earth's atmosphere first. A special category of satellite is one that is manned, such as theInternational Space Station (ISS), and they are used forexploration and research into the effects of long-term low gravity,international cooperation and the promotion of peace, among otherpurposes. Communication satellites can be used to send telephone messages orTV pictures. A satellite can be used for working out what theweather will be like in a few days. It has a sensor which send atelevision call to earth telling us what's going to happen. Theycan also be used for spying and navigation and they can spot forestfires and water pollution. 1st letter is S and ends with E! it transmits radio/ televideo/etc. waves It helps us by like if we atrapped some where and u have afone on u u can call 911 or someone who willhelp u They are used for exploring different planets in our solar system, transmitting radio, telephone, and television signals, and to tell what the weather is going to be like. many sencitest send artifical satalites some revolving around the earth. it is used dish antena The primary uses for an artificial satellite, given our current technology, are: .
Communication (television and cell phone satellites) .
Observation (the Hubble Space Telescope, weather satellites, ) .
Location (the GPS system) .
Habitation (Skylab, Mir, the International Space Station) As our technology continues to expand, it's likely that uses for artificial satellites will as well. For example, a military satellite might provide a way to defend specific nations, or even the Earth as a whole (from a meteor strike, for example). Or, as seen on sci-fi TV shows, a space dock could allow the repair and refueling of space vehicles, without the need to return to our planet's surface. There could eventually be space hotels, low- and zero-gravity tourist attractions, zero-gee factories, controlled-gravity hospitals... The list is bounded only by our imagination, and economic considerations. (MORE)