SAR data

Some Earth observation satellites use radar to monitor the planet. This is achieved with a technology called Synthetic Aperture Radar (SAR), an active system that emits microwave signals to illuminate the Earth’s surface and measures the reflected signals. The key advantages of SAR include its ability to penetrate through clouds and operate without sunlight. This means radar data can be collected at any time-day or night, regardless of weather conditions-making radar satellites highly suitable for monitoring and surveillance applications. 

Unlike how the human eye perceives the Earth, a radar satellite “senses” the surface differently-almost as if it “feels” it. SAR is particularly sensitive to surface roughness; rougher surfaces reflect more radar signals. This property makes radar an excellent tool for detecting oil spills, as oil smooths the sea surface, reducing its roughness. Radar data is also widely used for applications like flood mapping, tracking illegal fishing, ice monitoring, and agricultural analysis.

Moreover, radar data is capable of detecting and measuring even the smallest ground movements (subsidence) and changes in infrastructure. Movements as small as a few millimeters per year can be identified through InSAR (Interferometric Synthetic Aperture Radar) processing, which utilizes the phase component of radar signals. This valuable information is applied in various fields, including monitoring gas reservoirs, assessing dike stability, and tracking infrastructure shifts, such as buildings affected by tunnel-boring activities.