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For global communication coverage, what is the minimum number of satellites required in geostationary orbit?

Difficulty: Easy

Correct Answer: 3

Explanation:

Introduction / Context:
Geostationary satellites are positioned approximately 36,000 km above the equator. From this altitude, they can cover about one-third of Earth's surface. This principle is used in global satellite communication systems.

Given Data / Assumptions:

Earth circumference ≈ 40,000 km.
Coverage of each geostationary satellite ≈ one-third of Earth's surface.
Satellites must be spaced evenly to provide continuous coverage.

Concept / Approach:
Since each satellite covers about 120° longitude, three satellites equally spaced at 120° intervals can provide nearly full global communication coverage, except for polar regions.

Step-by-Step Solution:

Total angular coverage required = 360°.Coverage per satellite ≈ 120°.Number of satellites required = 360° / 120° = 3.

Verification / Alternative check:

Systems like INTELSAT confirm this with 3-satellite networks providing global coverage.

Why Other Options Are Wrong:

1: insufficient, covers only one-third of the globe.5 or 10: more than required, although they improve redundancy.6: similar reasoning, unnecessary for minimum coverage.

Common Pitfalls:

Assuming polar coverage—geostationary satellites cannot cover extreme polar regions.

For global communication coverage, what is the minimum number of satellites required in geostationary orbit?

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