Passive SAR satellite constellation for near-persistent earth observation: Prospects and issues

Over the last decades spaceborne synthetic aperture radar (SAR) has proved its capability as a remote sensing technique of great power and value. A number of precise SAR instruments (e.g., [1]–[4]) have been developed by space and defense agencies around the world and are being used today for a wide range of applications in wide-area land (e.g., [5]–[8]) and sea monitoring (such as [9]–[11]).