satelliter

Satelliter is a term occasionally used to refer to any body that orbits a planet or another larger body. In contemporary English, the standard word is satellite, and satelliter is regarded as archaic, regional, or nonstandard. The term may appear in historical texts or in speculative fiction.

There are two broad classes: natural satellites (such as Earth's Moon) and artificial satellites (spacecraft placed in orbit by humans). Artificial satellites support communications, weather monitoring, navigation, Earth observation, science, and military uses.

Orbits and mechanics: A satellite's motion is governed by gravity and described by orbital mechanics. Orbits are characterized by altitude, inclination, eccentricity, and period. Low Earth orbit (LEO) ranges from about 160 to 2,000 km; medium Earth orbit (MEO); geostationary orbit (GEO) at about 35,786 km where the orbital period matches Earth's rotation.

History: The first artificial satellite, Sputnik 1, was launched by the Soviet Union in 1957, followed by Explorer 1 of the United States in 1958. Since then, thousands of satellites have been launched; many operate in constellations for communications and Earth observation.

Current trends: The 21st century has seen large satellite constellations designed to provide global broadband, as well as advanced smallsats and CubeSats. Debris and conjunction risks require tracking and space-traffic management.

Related topics include satellite, orbital mechanics, and space debris.