Question

Which of the following correctly describes satellite constellation requirements?

1. LEO systems need more satellites than GEO for global coverage.

2. MEO requires more satellites than LEO.

3. GEO systems require only 3 satellites for most of the globe.

• A. 1 & 2 only
• B. 1 & 3 only
• C. 2 & 3 only
• D. All are correct

Answer 1

Answer:

B. 1 & 3 only

• Correct Answer: Option B (1 & 3 only)

• Statement 1: "LEO systems need more satellites than GEO for global coverage." - This is Correct.

• Low Earth Orbit (LEO) satellites orbit at altitudes of approximately 500-2000 km. Due to their low altitude, each LEO satellite can only "see" a small portion of Earth's surface. This means many LEO satellites are needed to achieve global coverage. In contrast, Geostationary Earth Orbit (GEO) satellites orbit at approximately 36,000 km and remain fixed above one point on Earth, with each satellite covering nearly 1/3 of Earth's surface.

• Statement 2: "MEO requires more satellites than LEO." - This is Incorrect.

• Medium Earth Orbit (MEO) satellites operate at altitudes between LEO and GEO (typically 8,000-20,000 km). Due to their higher altitude compared to LEO satellites, each MEO satellite can cover a larger area of Earth's surface. Therefore, MEO systems generally require fewer satellites than LEO systems for comparable coverage. For example, GPS (a MEO constellation) uses only 24 operational satellites, while LEO constellations like Starlink require thousands of satellites.

• Statement 3: "GEO systems require only 3 satellites for most of the globe." - This is Correct.

• GEO satellites orbit at an altitude where their orbital period matches Earth's rotation period (24 hours). Positioned strategically 120° apart, just 3 GEO satellites can provide coverage for most of Earth's surface (except extreme polar regions). Each GEO satellite can view approximately 1/3 of Earth's surface from its fixed position.