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

Astronomers explore globular cluster NGC 2419

Using the Indian Astronomical Observatory (IAO) and ESA's Gaia satellite, astronomers have explored a galactic globular cluster known as NGC 2419. Results of the study, published April 29 on the preprint server arXiv, shed ...

Researchers explore an old galactic open cluster

Using data from ESA's Gaia satellite, astronomers from Turkey and India have investigated NGC 188—an old open cluster in the Milky Way. Results of the study, published April 19 on the pre-print server arXiv, deliver important ...

How light can vaporize water without the need for heat

It's the most fundamental of processes—the evaporation of water from the surfaces of oceans and lakes, the burning off of fog in the morning sun, and the drying of briny ponds that leaves solid salt behind. Evaporation ...

New tidal stellar stream discovered with Gaia

By analyzing the data from ESA's Gaia satellite, Chinese astronomers have detected a new tidal stellar stream in the northern hemisphere, which has a low metallicity and a relatively high energy. The finding was reported ...

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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.

This text uses material from Wikipedia, licensed under CC BY-SA