Synthetic aperture radar (SAR) is a method to make sharp footage even when it’s darkish or cloudy. Instead of utilizing seen mild like an everyday digital camera, 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 photos.
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 laborious to construct and preserve. On a SAR, a small antenna is carried on a transferring 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 part info, software program will help mimic a single antenna tons of of metres lengthy.
Since microwaves penetrate clouds, smoke, and even mild rainfall, SAR can accumulate knowledge 24/7. If a SAR unit is mounted on an orbiting satellite tv for pc, it may well map swaths of land tons of of kilometres extensive in a single overpass. Different supplies like soil, vegetation, water, and metals mirror microwaves in another way, permitting SAR to detect adjustments invisible to optical sensors.
On June 12, NASA stated 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
