In which of the following activities are Indian Remote Sensing (IRS) satellites used?

1. Assessment of crop productivity

2. Locating ground water resources

3. Mineral exploration

4. Telecommunications

5. Traffic studies

Select the correct Answer using the code given below:

The correct option is 1, 2 and 3 only.

Indian Remote Sensing (IRS) satellites are primarily designed and used for earth observation, monitoring, and management of natural resources. Let's analyze each of the given activities to understand why they are (or are not) applications of IRS satellites:

1. Assessment of crop productivity: IRS satellites are equipped with multispectral sensors that can measure the reflectance of vegetation. This spectral data helps in identifying crop types, monitoring crop health, and estimating crop yield and productivity over large agricultural areas. Therefore, this is a correct application.

2. Locating ground water resources: Remote sensing data helps in mapping geological features, geomorphology, drainage patterns, and land use/land cover. These factors are crucial indicators for identifying potential groundwater recharge zones and locating groundwater resources. Therefore, this is a correct application.

3. Mineral exploration: IRS satellites provide high-resolution spectral and spatial data that help geologists map surface geology, identify alteration zones, and detect specific mineral signatures on the Earth's surface. This facilitates targeted mineral exploration. Therefore, this is a correct application.

4. Telecommunications: Telecommunications require geostationary communication satellites (such as the INSAT or GSAT series in India) which are positioned in a much higher orbit (around 36,000 km) to cover wide regions and provide continuous connectivity. IRS satellites operate in low Earth polar/sun-synchronous orbits and are not configured or equipped for telecommunication services. Thus, this is not a correct application.

5. Traffic studies: While high-resolution remote sensing can occasionally capture snapshots of urban areas, continuous traffic studies and monitoring are typically done using ground-based sensors, cameras, or GPS-based tracking systems, rather than remote sensing satellites. Thus, this is not a standard or practical application for IRS satellites.

Based on the analysis, activities 1, 2, and 3 are correct applications of IRS satellites, whereas activities 4 and 5 are not.