lowEarthorbit

Low Earth orbit (LEO) refers to orbits close to the Earth's surface, typically defined as altitudes from about 160 kilometers (100 miles) to 2,000 kilometers (1,200 miles). In LEO, objects complete an orbit roughly every 90 to 120 minutes, depending on altitude and inclination. The proximity to Earth enables high‑resolution imaging, relatively low-latency communications, and easier crewed access, but it also subjects spacecraft to higher atmospheric drag and radiation compared with higher orbits.

Because of these characteristics, most spaceborne platforms placed in the near-Earth region are satellites for Earth observation, reconnaissance, science, technology demonstrations, and many commercial communications or data-relay missions. The International Space Station operates in LEO at roughly 408 kilometers, serving as a laboratory and living habitat. Mega-constellations such as Starlink and OneWeb also operate in LEO at various altitudes, often around 550 to 1,200 kilometers.

Atmospheric drag in LEO causes gradual orbital decay that requires occasional reboosts to maintain altitude and ground track. The remaining service life of a satellite in LEO depends on altitude, solar activity, and cross-sectional area. At the lowest LEO, objects can re-enter within days or months if propulsion is not used; higher LEO can sustain satellites for many years with proper stationkeeping. End-of-life disposal rules reduce debris by deorbiting or raising the orbit.

Space debris and collision avoidance are significant concerns in LEO due to the high density of man-made objects and the potential for cascading collisions (the Kessler syndrome). Ground-based radar and optical tracking networks monitor objects and provide conjunction alerts to prevent collisions.