Related topics: nasa · space · launch · earth · orbit

NASA finds depression strengthen into Tropical Storm Dalila

Satellite imagery on July 22 showed that wind shear was preventing the Eastern Pacific Ocean's Tropical Depression 5 from consolidating and strengthening. Infrared imagery from NASA's Aqua satellite on July 23 showed that ...

NASA tracking post-tropical cyclone Barry to Indiana

NASA's Aqua satellite provided a visible image of the clouds associated with Post-Tropical Cyclone Barry moving through the mid-Mississippi Valley on July 16, and headed toward the Ohio Valley.

Europe's GPS rival Galileo suffers outage

Europe's Galileo satellite position system, a future rival of the American GPS network, has been out of service since Friday, its oversight agency said.

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Satellite

In the context of spaceflight, a satellite is an object which has been placed into orbit by human endeavor. Such objects are sometimes called artificial satellites to distinguish them from natural satellites such as the Moon.

The first artificial satellite, Sputnik 1, was launched by the Soviet Union in 1957. By 2009 thousands of satellites have been launched into orbit around the Earth. These originate from more than 50 countries and have used the satellite launching capabilities of ten nations. A few hundred satellites are currently operational, whereas thousands of unused satellites and satellite fragments orbit the Earth as space debris. A few space probes have been placed into orbit around other bodies and become artificial satellites to the Moon, Venus, Mars, Jupiter and Saturn.

Satellites are used for a large number of purposes. Common types include military (spy) and civilian Earth observation satellites, communication satellites, navigation satellites, weather satellites, and research satellites. Space stations and human spacecraft in orbit are also satellites. 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 orbit, and geostationary orbit.

Satellites are usually semi-independent computer controlled systems. Satellite subsystems attend many tasks, such as power generation, thermal control, telemetry, attitude control and orbit control.

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