Describe the different satellite orbits and their relative advantages.

Types of Satellite Orbits and Their Advantages

Satellite orbits are broadly classified based on their altitude and inclination. Here's a detailed look at the major types:

1. Low Earth Orbit (LEO)

• Altitude: 160 – 2,000 km
• Characteristics: Short orbital period (around 90-120 minutes), requires frequent station-keeping maneuvers.
• Advantages:
  • High resolution imagery due to proximity to Earth.
  • Low latency, ideal for real-time communication.
  • Lower launch costs compared to higher orbits.
• Applications: Earth observation (Landsat, SPOT), scientific research, the International Space Station (ISS), and constellations for broadband internet (Starlink, OneWeb).

2. Medium Earth Orbit (MEO)

• Altitude: 2,000 – 35,786 km
• Characteristics: Longer orbital periods than LEO, moderate latency.
• Advantages:
  • Wider coverage area than LEO.
  • Requires fewer satellites for global coverage compared to LEO.
• Applications: Navigation systems (GPS, Galileo, GLONASS), regional communication networks.

3. Geostationary Orbit (GEO)

• Altitude: Approximately 35,786 km
• Characteristics: Orbital period matches Earth’s rotation, appearing stationary from the ground.
• Advantages:
  • Continuous coverage of a specific region.
  • Simple ground station tracking – no need for complex steering.
• Applications: Communication satellites (INTELSAT, Inmarsat), weather monitoring (GOES, Meteosat), broadcasting.

4. Highly Elliptical Orbit (HEO)

• Altitude: Highly variable, ranging from perigee (low altitude) to apogee (high altitude).
• Characteristics: Long orbital period, spends a significant amount of time over a specific region at apogee.
• Advantages:
  • Extended coverage of high-latitude regions.
  • Useful for communication and surveillance in areas poorly served by GEO satellites.
• Applications: Communication in polar regions (Molniya orbit – used by Russia), surveillance.

5. Sun-Synchronous Orbit (SSO)

• Altitude: Typically between 600 – 800 km
• Characteristics: Inclination designed to ensure the satellite passes over a given point on Earth at the same local solar time.
• Advantages:
  • Consistent lighting conditions for Earth observation.
  • Ideal for remote sensing and mapping.
• Applications: Earth observation (Landsat, Sentinel), weather monitoring, environmental monitoring.

The following table summarizes the key differences:

Orbit Type	Altitude (km)	Orbital Period	Coverage	Latency	Applications
LEO	160 – 2,000	90-120 minutes	Limited	Low	Earth Observation, Communication, ISS
MEO	2,000 – 35,786	Several hours	Moderate	Moderate	Navigation (GPS), Regional Communication
GEO	35,786	24 hours	Wide (Fixed)	High	Communication, Weather Monitoring
HEO	Variable	Up to 12 hours	Regional (Polar)	Variable	Polar Communication, Surveillance
SSO	600 – 800	90-100 minutes	Global (Consistent Lighting)	Low	Earth Observation, Remote Sensing