Synthetic-aperture radar (SAR) is a form of radar which is used to create images of an object, such as a landscape. SAR uses the motion of the SAR antenna over a target region to provide finer spatial resolution than is possible with conventional beam-scanning radars.
An overview of satellite synthetic aperture radar remote sensing in archaeology: From site detection to monitoring — ScienceDirect
U.S., India to Collaborate on Mars Exploration, Earth-Observing Mission - The NASA-ISRO Synthetic Aperture Radar (NISAR) mission, targeted to launch in 2020, will make global measurements of the causes and consequences of a variety of land surface changes on Earth. Image Credit: NASA