Paper: GS – III, Subject: Science & Technology, Topic: Space Technology, Issue: Remote Sensing Technology.
Context:
Advances in Remote Sensing Technology using satellites and drones are transforming how scientists study plants, forests, water bodies, minerals, and underground resources without physically touching the Earth’s surface.
- By analysing spectral signatures across visible and invisible wavelengths, remote sensing is reshaping environmental management, resource exploration, and climate science.
Key Takeaways:
What is Remote Sensing Technology?
- Remote sensing is a technology that allows scientists and engineers to map Earth’s resources without physically touching the ground.
- It involves detecting and analyzing electromagnetic energy (light) reflected from different materials on Earth.
- Different materials (rocks, water, trees, etc.) reflect these energies differently, creating unique “spectral signatures.”
- For example, a sensor might detect high near-infrared reflection and low red-light absorption, indicating a healthy plant.
How Remote Sensing Technology Works for Plants and Forests:
- Farmers and forest rangers use satellites to monitor plant health.
- Healthy leaves contain chlorophyll, which absorbs red light for photosynthesis and reflects near-infrared light to prevent overheating.
- This mapping is crucial for calculating forest biomass (weighing trees from space) to understand carbon storage and combat climate change.
Mapping Water Bodies from Space:
- Two main techniques are used to map water bodies: optical indexing and synthetic aperture radar (SAR).
- Optical Indexing:
- Water reflects visible green light but strongly absorbs near-infrared and shortwave infrared light.
- The Normalized Difference Water Index (NDWI) combines these readings to identify water bodies.
- A modified version, MNDWI, uses only shortwave infrared light and is better at distinguishing water from shadows in urban areas.
- Optical cameras cannot see through clouds or at night.
- Synthetic Aperture Radar (SAR):
- SAR uses active radio waves to map surfaces, even in cloudy or nighttime conditions.
- Surfaces like soil and buildings scatter radio waves and appear bright in SAR images.
- Calm water is smooth and reflects radio waves away, appearing black.
- SAR can map floodwaters even during storms.
- Satellites can also estimate water quality by analyzing the spectral signatures of muddy water or water with algae blooms.
Benefits of Remote Sensing Technology:
- Faster and Cheaper Exploration: Remote Sensing Technology allows us to target specific areas for drilling, reducing the need for extensive and costly exploration.
- Environmental Protection: By monitoring forests and aquifers from space, we can ensure sustainable resource management.
Conclusion:
Remote Sensing Technology has evolved into a foundational tool of modern Earth science, enabling humanity to monitor ecosystems, manage resources, and respond to climate change with unprecedented precision—turning satellites into silent custodians of the planet.
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