Question

Given below are two statements, one is labelled as Assertion A and the other is labelled as Reason R
Assertion A: In a Global Positioning System (GPS), four satellites are accommodated in each orbit at an altitude of 20,185 km from surface of earth.
Reason R: All these GPS satellites are placed in six orbits.
In light of the above statements, choose the correct answer from the options given below:

• A. Both A and R are true and R is the correct explanation of A
• B. Both A and R are true but R is NOT the correct explanation of A
• C. A is true but R is false
• D. A is false but R is true

Hint:

Remember the standard layout of the GPS space segment:
\[ 6 \text{ orbital planes} \times 4 \text{ satellites per plane} = 24 \text{ primary operational satellites} \]
This configuration provides the geometric distribution required for accurate triangulation.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
The Global Positioning System (GPS) is a satellite-based radionavigation system owned by the United States government.
The space segment of the GPS constellation is designed to ensure that at least four to eight satellites are visible from almost any point on the Earth's surface at any given time.

Step 2: Detailed Explanation:
Let us analyze both the Assertion and the Reason:
- Assertion A: The standard operational GPS constellation consists of 24 primary satellites orbiting the Earth.
These satellites operate in circular orbits at an altitude of approximately \( 20,185 \text{ km} \) (or roughly \( 20,200 \text{ km} \)) above the Earth's surface.
To ensure uniform global coverage, the satellites are distributed so that exactly four satellites are positioned in each orbital plane.
Therefore, Assertion A is true.
- Reason R: The 24 satellites are distributed across six equally spaced orbital planes, designated as planes A through F.
Each of these six planes is inclined at an angle of \( 55^\circ \) relative to the Earth's equator.
Placing the satellites in these six distinct orbits, with four satellites in each orbit, ensures that a receiver on Earth can always receive signals from the minimum of four satellites required to calculate a 3D position (latitude, longitude, altitude, and time).
Therefore, Reason R is true and provides the direct structural explanation for why the satellites are distributed as described in Assertion A.

Step 3: Final Answer:
Both A and R are true and R is the correct explanation of A.