Types of Orbits: Orbits Based on Altitude & Functionality​ - UPSC Notes

Syllabus

General Studies - Paper III

Topics for Prelims

Artificial Satellites, Space technology

Topics for Mains

India's space programs

Orbit Type

Low Earth Orbit (LEO)

Medium Earth Orbit (MEO)

Geostationary Orbit (GEO)

Altitude

160 km to 2,000 km

2,000 km to 35,786 km

35,786 km above Earth’s equator

Orbit Characteristics

Satellites in LEO are closest to Earth, orbiting in about 90 minutes. Used for weather monitoring, Earth observation, and communication.

MEO satellites orbit at higher altitudes (2-24 hours per orbit). Used for navigation systems.

GEO satellites appear stationary relative to Earth, orbiting at the same rate as Earth's rotation. Ideal for communication and weather observation.

Usage

The International Space Station (ISS), Earth observation satellites, communication satellites

Global navigation systems (GPS, Galileo, GLONASS)

Communication satellites, weather satellites, broadcasting satellites

Advantages

Low latency, high-resolution images of Earth

Longer lifespan compared to LEO, larger coverage area

Continuous coverage of specific areas, ideal for broadcasting and weather

Disadvantages

Shorter lifespan due to atmospheric drag, must be repositioned often

Higher communication delay compared to LEO due to increased distance

Longer signal delays, requires significant energy to reach and maintain position

Orbit Type

Polar Orbit

Sun-Synchronous Orbit (SSO)

Inclined Orbit

Elliptical Orbit

Orbit Characteristics

A satellite passes over Earth's poles, covering the entire surface over time as Earth rotates beneath it. Typically a low Earth orbit.

A polar orbit where the satellite's angle with respect to the Sun is fixed, ensuring consistent lighting conditions.

The satellite’s orbit is tilted relative to Earth's equator, often used for communication satellites at different latitudes.

Orbits with varying altitudes, increasing in velocity near Earth and decreasing as it moves away, offering diverse mission designs.

Usage

Earth observation satellites, scientific satellites, environmental monitoring (weather, climate, agriculture).

Earth observation satellites needing consistent observation at the same local solar time, for environmental studies.

Satellites for communication or remote sensing, covering regions GEO satellites cannot.

Satellites requiring variable coverage or flexible observation for high-resolution images or communications.

Advantages

Provides global coverage, useful for mapping and weather observation.

Ideal for precise and repetitive observation with consistent lighting conditions.

Offers flexibility in terms of the area covered and allows satellites to serve various latitudes.

Offers varying speeds and altitudes, useful for specific purposes like high-resolution imagery or communication flexibility.

Disadvantages

Higher speed, requiring frequent adjustments and energy consumption.

Requires exact alignment with Earth's precession, making the launch complex.

Less stable than geostationary orbits, requiring more frequent adjustments.

Requires managing high-speed and low-speed movements, and satellite conditions may impact communication and observation at certain altitudes.