Question

The Indian Remote Sensing Satellite (IRS)
(A). Look over a fixed point at the same local time
(B). Are at a low altitude ($<1000$ km)
(C). Are used for weather forecasting
(D). Have large agricultural and natural resources application
(E). Provide service to telecommunications
Choose the correct answer from the options given below:

• A. (A), (B) and (D) only.
• B. (A), (B) and (C) only.
• C. (A), (B), (C) and (D).
• D. (A), (D) and (E) only.

Hint:

Remember:
- Low Earth Orbit Sun-synchronous (e.g., IRS): Earth observation and resource mapping.
- Geostationary Orbit (e.g., INSAT): Weather monitoring and telecommunications.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Satellites are designed for different orbits (polar vs. geostationary) depending on their specific remote sensing, meteorological, or telecommunication functions.

Step 2: Detailed Explanation:
Let us evaluate each characteristic for the Indian Remote Sensing (IRS) satellite series:
- Statement (A) is correct: IRS satellites operate in sun-synchronous polar orbits, meaning they cross the equator at the same local solar time on each pass, providing consistent lighting conditions for image comparison.
- Statement (B) is correct: They are low Earth orbit (LEO) satellites, operating at altitudes typically between 700 km and 900 km (which is $<1000$ km).
- Statement (D) is correct: The primary application of IRS satellites is Earth observation, which includes monitoring agriculture, forestry, water resources, and geological features.
- Statements (C) and (E) are incorrect: Geostationary satellites (such as the INSAT and GSAT series) operating at higher altitudes ($\approx 36,000$ km) are used for weather forecasting and telecommunication services, rather than polar-orbiting IRS satellites.
Therefore, only (A), (B), and (D) are correct.

Step 3: Final Answer:
The correct option is (A).