Synthetic aperture radar (SAR) is a option to make sharp footage even when it’s darkish or cloudy. Instead of utilizing seen mild like an everyday digicam, SAR programs ship out microwave pulses and document the echoes that bounce again from the bottom, ocean, ice or buildings. Then, intelligent sign processing turns these echoes into detailed pictures.
The key ingredient is the antenna that receives the echoes. Usually, the longer a bodily antenna, the higher the decision — however a big antenna is exhausting to construct and keep. On a SAR, a small antenna is carried on a shifting platform like a satellite tv for pc. As a consequence every echo is recorded at a barely totally different place. By stitching them along with exact timing and section data, software program will help mimic a single antenna a whole lot of metres lengthy.
Since microwaves penetrate clouds, smoke, and even mild rainfall, SAR can accumulate information 24/7. If a SAR unit is mounted on an orbiting satellite tv for pc, it might probably map swaths of land a whole lot of kilometres huge in a single overpass. Different supplies like soil, vegetation, water, and metals mirror microwaves in a different way, permitting SAR to detect adjustments invisible to optical sensors.
On June 12, NASA mentioned the NASA-ISRO SAR (NISAR) mission had arrived at ISRO’s spaceport in Sriharikota. Once it’s launched, NISAR will “scan nearly all of earth’s land and ice surfaces twice every 12 days”, offering “an unprecedented amount of information about our planet’s environment”.
Published – June 17, 2025 08:37 am IST
