Remote-sensing Technology:
Context:
Remote-sensing technology is increasingly used by engineers and scientists to map land, forests, water bodies, and minerals without physically touching the ground.
About the Technology:
Remote sensing involves using satellites and drones to detect spectral signatures—unique fingerprints of materials based on how they reflect visible and invisible light (like infrared and ultraviolet).
Unlike normal cameras that group light into three colors, hyperspectral sensors split light into hundreds of narrow frequencies.
This allows them to identify specific tree species or mineral deficiencies in soil with high precision.
Key Applications:
Agriculture and Forests:
Satellites assess plant health by measuring chlorophyll levels; healthy plants reflect more near-infrared light.
This data helps calculate forest biomass and carbon storage.
Water Mapping:
Techniques like the Normalised Difference Water Index (NDWI) use optical data to map water bodies.
For all-weather monitoring (during cyclones), Synthetic Aperture Radar (SAR) is used as it can see through clouds and darkness.
Mineral and Oil Exploration:
Satellites detect surface traces of minerals like lithium or gold.
They also identify oil reserves by detecting micro-seepage, where leaking gas alters surface soil chemistry and vegetation colour.
Groundwater Monitoring:
Missions like NASA’s GRACE use gravitational pull measurements to weigh underground aquifers.
This technology notably revealed alarming groundwater depletion rates in North India.