(a) Applications of Satellite Systems in Five Different Fields

  1. Communication

    • Used for television broadcasting (DTH), mobile and internet connectivity, and satellite phones.

    • Examples: INSAT, Iridium, Starlink.

  2. Navigation

    • Enables GPS-based location tracking and navigation for transport, aviation, and military applications.

    • Examples: GPS, GLONASS, Galileo, NavIC.

  3. Earth Observation & Remote Sensing

    • Helps in weather forecasting, disaster management, agriculture, and environmental monitoring.

    • Examples: Landsat, Sentinel, Cartosat.

  4. Scientific Research & Space Exploration

    • Supports space missions, planetary exploration, and space telescopes for astronomical studies.

    • Examples: Hubble Telescope, Chandrayaan, Mars Rover Missions.

  5. Military & Defense

    • Used for surveillance, reconnaissance, secure communication, and missile guidance.

    • Examples: MILSTAR, GSAT-7, KH-11 reconnaissance satellites.

(b) Types of Satellite Orbits & Their Altitudes

  1. Low Earth Orbit (LEO) (180 – 2,000 km)

    • Used for Earth observation, space stations, and communication satellites.

    • Example: ISS (International Space Station), Starlink.

  2. Medium Earth Orbit (MEO) (2,000 – 35,786 km)

    • Mainly used for navigation systems like GPS and communication.

    • Example: GPS, Galileo satellites.

  3. Geostationary Orbit (GEO) (35,786 km above the equator)

    • Satellites appear fixed from Earth, used for TV broadcasting, weather monitoring.

    • Example: INSAT, GOES weather satellites.

  4. Highly Elliptical Orbit (HEO) (Perigee: ~500 km, Apogee: ~40,000 km or more)

    • Used for high-latitude communications and scientific missions.

    • Example: Molniya orbit satellites.

Each orbit serves a specific purpose, balancing coverage, speed, and energy efficiency.