Synthetic-aperture radar imaging is different to how optical imaging works. While optical cameras rely on light created by other sources, like the Sun, a radar instrument actively sends its own radio waves towards its target and then measures what is reflected back.
A "synthetic-aperture" means physically moving the small SAR instrument over an area, while it gathers information of its target, rather than having a very large instrument which would image the same area at once. To achieve this movement, SAR instruments are often mounted on satellites and airplanes, which enables them to cover large areas in a very short time.
SAR image processing is used to turn the gathered data into reliable and clear pictures, readable by both humans and algorithms.
Due to the way they are gathered, SAR images have distinct features that make it a reliable method of observing our planet Earth. The instrument does not require sunlight, so it can be used to image areas during the night as well as during the day. ICEYE SAR instruments use X-band radio waves for gathering data, which can penetrate through cloud cover.