satelitet

Satelitet is a term used in several Scandinavian languages for a satellite. In general, a satelitet is an object that orbits a planet or other body, kept in orbit by gravity. They can be natural (moons) or artificial (made by humans).

Artificial satellites consist of a bus and a payload. The bus provides structure, power, communications, attitude control, and propulsion; the payload performs the mission objective (telecommunications, imaging, sensors). They are placed into orbit by launch vehicles.

Orbits: Low Earth Orbit (LEO) up to about 2000 km; Medium Earth Orbit (MEO); Geostationary Orbit (GEO) at about 35,786 km where the orbital period matches Earth's rotation; highly elliptical orbits (HEO) used for certain missions. The choice affects coverage, latency, and lifetime.

History: The first artificial satellite, Sputnik 1, launched by the Soviet Union in 1957, marked the start of the space age. Since then, decades of development have produced space observatories, navigation satellite constellations, weather satellites, etc.

Uses: Communications satellites provide telephony and internet; weather satellites monitor climate and severe weather; Earth observation satellites collect imagery and data; navigation systems (GPS/Galileo) provide positioning; scientific missions explore space and planetary science, sometimes with military applications.

Governance and safety: Space law includes the Outer Space Treaty (1967) and subsequent agreements. Space debris is a concern; adherence to deorbiting or moving to a graveyard orbit at end of life is common; space traffic management and collision avoidance are increasingly important as the number of objects grows.