Satellites, Orbits & Satellite Constellations
Artificial satellites operate in designated orbital regimes tailored to specific communication, navigation, and Earth observation missions. Low Earth Orbit (LEO, 160–2,000 km) accommodates the International Space Station (ISS) and broadband mega-constellations like Starlink and OneWeb. Geostationary Earth Orbit (GEO), situated precisely at an altitude of 35,786 kilometers above the equator, enables telecommunication and meteorological satellites to maintain a stationary footprint relative to Earth's rotation. Global Navigation Satellite Systems (GNSS) provide precise positioning, comprising the United States' GPS, Russia's GLONASS, Europe's Galileo, China's BeiDou, and India's regional satellite navigation system, NavIC (Navigation with Indian Constellation).
Key Concepts & Examination Highlights
- Geostationary Earth Orbit (GEO) satellites maintain a circular orbit exactly 35,786 kilometers above Earth's equator with an orbital period of 24 sidereal hours.
- NavIC (Navigation with Indian Constellation), developed by ISRO, consists of a constellation of 7 operational satellites providing positioning services across India.
- The International Space Station (ISS) orbits Earth in Low Earth Orbit at an altitude of approximately 400 kilometers, completing roughly 16 orbits per day.