General Science
Mains: Awareness in the field of Space
Why it Matters?
Recently, the National Aeronautics and Space Administration (NASA) announced that the NASA–Indian Space Research Organisation Synthetic Aperture Radar (NISAR) mission arrived at the Satish Dhawan Space Centre in Sriharikota on May 15, 2025, marking a key milestone ahead of its scheduled July launch.
What You Should Know?
Type of Sensor: Synthetic Aperture Radar (SAR) is an active remote sensing system that emits microwave pulses and records reflected signals from Earth’s surface.
All-Weather Capability: SAR can capture high-resolution images day and night, even through clouds, smoke, and light rain.
Working Principle: SAR collects echoes from multiple positions on a moving platform to synthetically create the effect of a large antenna.
Imaging Mechanism: It uses microwave signals, which interact with natural and man-made features, allowing image creation through signal processing of returned echoes.
Resolution Advantage: Instead of building a large antenna, SAR uses motion and software to simulate an antenna hundreds of metres long for better resolution.
Platform: SAR systems are often mounted on satellites or aircraft, enabling them to cover wide swaths of land in a single pass.
Surface Discrimination: SAR distinguishes between different materials like soil, vegetation, water, and metals due to varied microwave reflection properties.
Use in Environmental Monitoring: SAR is useful for tracking deforestation, ice movements, floods, and soil moisture, and for applications in military reconnaissance and disaster response.
Recent Example: The NASA-ISRO Synthetic Aperture Radar (NISAR) mission is designed to scan almost all of Earth’s land and ice surfaces twice every 12 days.